FUKASHERE ADMISSION LIST 2017/2018 IS OUT

                    FUKASHERE ADMISSION LIST 2017/2018

APPLICANTS AND GENERAL PUBLIC ARE HEREBY INFORMED THAT THE MANAGEMENT OF FEDERAL  UNIVERSITY, KASHERE HAS RELEASED THE FIRST BATCH LIST OF CANDIDATES OFFERED PROVISIONAL ADMISSION INTO THE UNIVERSITY'S UNDERGRADUATE PROGRAMME FOR THE 2017/2018 ACADEMIC SESSION.
CANDIDATES CAN PROCEED TO CHECK  THEIR ADMISSION STATUS ONLINE BY:
- CLICKING ON https://portal.fukashere.edu.ng/#/login
- ENTER YOUR USERNAME AND PASSWORD IN THE APPROPRIATE COLUMNS
-LOGIN TO CHECK YOUR ADMISSION STATUS

MPS PhD POSITIONS AT THE UNIVERSIRTY OF GOTTINGEN, GERMANY

Scholarship Description:
The Max Planck Research School for Solar System Science (MPS) at the University of Göttingen is now accepting applications for PhD positions in Solar System Science. The call is open to students from all countries and offers an international three-year Ph.D. program.

The International Max Planck Research School (IMPRS) for Solar System Science at the University of Göttingen is a Ph.D. programme at the interface of geo- and astrophysics. The IMPRS, or Solar System School as it is known, in short, covers all areas of Solar system science, an interdisciplinary research field that comprises space exploration and the planetary sciences as well as Solar physics, and selected topics in the areas of stellar astrophysics and extra-solar planetary systems.

Positions are available to pursue PhD programme.

Positions are awarded in Solar System Science. Research at the MPS covers three main areas:

• “Sun and Heliosphere”,
• “Solar and Stellar Interiors”,
• “Planets and Comets”.

 Successful applicants will be offered a three-year doctoral support contract as well as postdoc wrap-up funding.

 About 45 students are enrolled at any given time. Their funding comes from several sources. The yearly call for applications primarily addresses candidates applying for an IMPRS-funded position, but anyone hired on a project position and desiring to pursue work towards a Ph.D. under the roof of the IMPRS also needs to submit an application to IMPRS. In some cases, applicants for IMPRS positions will also be redirected to open project positions suitable to pursue Ph.D. work. We admit about 10-15 Ph.D. students in total per year.

Eligibility:
The following criteria must be met in order for applicants to be eligible for the scholarship:

• Solar System School students collaborate with leading scientists in these fields and graduates are awarded a doctoral degree from the renowned University of Göttingen or, if they choose, another university.
• The Solar System School is open to students from all countries and offers an international three-year Ph.D. program in an exceptional research environment with state-of-the-art facilities on the Göttingen Campus. Successful applicants will be offered a three-year doctoral support contract as well as postdoc wrap-up funding.
• The language of the structured graduate program in English, with complimentary German language courses offered (optional). The program includes an inspiring curriculum of scientific lectures and seminars as well as advanced training workshops and provides relocation costs and travel funds to attend international conferences.
• Applicants to the Solar System School should have a keen interest in Solar system science and a record of academic excellence. They must have or must be about to obtain, an M.Sc. degree or equivalent in physics, earth sciences or a related field, including a written Master’s thesis, and must document a good command of the English language. The Solar System School is open to students from all countries.

Application Procedure: Applicants must submit the following documents through the online application portal between 1 October and 15 November 2017:

• An application form to be filled online, including two short texts describing the applicant’s scientific interests and their motivation to apply for PhD projects in the Solar System School, along with the applicant’s choice of up to three PhD projects;
• A curriculum vitae in pdf format;
• Degree certificates and full transcripts of all academic records: i.e. scanned copies of B.Sc. and M.Sc. degree certificates (or equivalent), and lists of all courses with credits and grades issued by the respective school or university, with English or German translations;
• Contact details for two or more referees who have agreed to write a letter of recommendation on behalf of the applicant. The referees will be contacted by the School and will be asked to submit their letters through the online portal no later than November 20, 2017.

• It is highly recommended to also submit

• certificate to prove proficiency in the English language, for candidates whose native language is not English or German (e.g. transcript of TOEFL / IELTS scores or equivalent);
• GRE Physics test scores or equivalent for candidates who have obtained their Master’s degree at a university outside of Europe.
• The Solar System School is committed to diversity. The MPS is an equal opportunity employer and places particular emphasis on providing career opportunities for women. Applications of people with disabilities are encouraged and will be favoured in case of comparable qualifications.

Application Form

Deadline: The deadline for submission of application is November 15, 2017.

ENVIRONMENTAL POLLUTION CONTROL LAWS

Environmental Pollution Control Laws
• Federal environmental protection agency (FEPA) decree No. 58 of 1988 amended to FEPA acts of 1992
• National environmental protection (pollution abatement in industries and facilities generating wastes) regulation 1991
• Environmental impact assessment decree No. 86 of 1992
• National environmental protection (management of solid and hazardous wastes) regulation of 1991
• Factories decree of 1987
• Land use decree of 1978
National Environmental Protection (pollution abatement in industries and facilities generating wastes) Regulation 1991
It stipulates that industries are supposed to have a pollution monitoring unit at each site to analyse all discharge and make monthly report to FEPA. Accidental or unusual discharge must be reported to FEPA within 24 hours.
Factories Decree of 1987 (as amended to factories act)
Certain provisions or sections of this law are to protect the environment from pollution and contamination e.g section 45 (2) states that no stationary internal combustion shall be used unless provision is made for conducting the exhaust gases from the engine into the open air. It provides the protection of workers, in connection with the process dust, fume or other impurity of such a character and to such an extent as to be likely injurious to persons employed therein e.t.c.
Environmental Impact Assessment Decree (as amended to FEPA act of 1992)
This law compels every major development project, which is likely to have an adverse impact on the environment, to be subjected to an environmental impact assessment. Older projects that have polluted the environment will be audited and re-organised for safer production and services.
The Environmental Sanitation Edicts
These edicts exist in many states of the federation with slight modification in titles. For instance in Kogi state, we have the sanitation Edict No. 12 of 1998. The major provisions of these edicts include the establishment of bodies responsible for environmental sanitation, prescription of environmental offences and penalties. In terms of scope, it covers sanitation issues of waste disposal, industrial and commercial pollution, noise pollution control and pest and vector control e.t.c.
POTENTIAL HAZARDS OF WATER
There are other substances that may contaminate water under certain conditions if present in high concentrations. The table below is a list of substances that are toxic and their maximum allowable concentrations in water according to World Health Organization (WHO):

Toxic substances Maximum allowable levels (mg/l)
Selenium (Se) 0.05
Arsenic (As) 0.01
Lead (Pb) 0.05
Cyanide (CN) 0.2
Mercury (Hg) 0.01
Barium (Ba) 1.0
Fluorides (F) 0.8-1.0

If these substances have values in water higher than that quoted above, they will cause ill-health and death ultimately.
Potential Hazards of Air
Hazardous substances are emitted into the air by a number of sources
Toxic substances Sources
Abestos Construction, demolition of existing structures, abestos mining, soil erosion
Mercury Choroalkali manufacture, battery manufacture and solid waste incinerator
Benzene Petrochemical and pharmaceutical industries and industrial solvents
Arsenic Copper smelting and glass manufacture
Fluorides Aluminium smelting and phosphate fertilizer manufacture
Radioactive substances


Potential Hazards of Soil
Sulphur present in fumes is responsible for acid rain and consequently lowers the pH of the soil.
Chlorine and nitrogen oxides are other common gaseous pollutants which combine with water and pollute the soil.
Magnesite dust affects very adversely the soil property such as rise in pH, decrease in exchangeable K, Ca, Mg and available P and K to almost a critical level.

MASTERS/PhD INTERNATIONAL SCHOLARSHIP OPPORTUNITIES: UNIVERSITY OF SYDNEY, AUSTRALIA

University of Sydney International Scholarships (USydIS)

Last updated: 26 Jul 2017 |

University of Sydney 
Masters/PhD Degree

Deadline: admissions deadline
Study in:  Australia
Course starts 2018 

Brief description:

The University of Sydney invites candidates who are eligible to undertake a Postgraduate Research Degree or Master’s by Research program at this University to apply for the University of Sydney International Research Scholarship (USydIS).  The objective of the USydIS is to attract top quality international postgraduate students to undertake research projects which will enhance the University’s research activities.

Host Institution(s):

University of Sydney in Australia

Level/Fields of study:

Postgraduate Research Degree or Master’s by Research program in all research disciplines (but would depend on Faculty)

Number of Awards:

Not specified.

Target group:

International students commencing in both the March (Research Period 2) and July (Research Period 3).

Scholarship value/inclusions/duration:

The USydIS will cover tuition fees and living allowance for up to three years with a possibility of one semester’s extension for PhD students.

Eligibility:

To be eligible for the USydIS, you must:

• • Be an international student commencing full time enrolment in a Higher Degree by Research (HDR) at this University. Students may also be considered up until they have consumed a maximum of six months of course candidature.
• • Be a student undertaking study in a subject area identified by the University as within the areas of its current and emerging research strengths.
• • Not hold a research qualification regarded to be equivalent to an Australian Research Doctorate degree, or, if undertaking a Research Master’s degree, not hold a research qualification regarded to be equivalent to or higher than an Australian Research Master’s degree.
• • Not have held an Australia Award scholarship within two years prior to commencing the RTP Fee Scholarship.
• • Not be receiving a scholarship for which course tuition is a component under any other scholarship scheme to which the Australian Government makes a substantial contribution.
• • Not previously have received an RTP Fee Scholarship, unless the previous scholarship was for a Master by Research degree that you have completed and you are now applying for a doctorate research degree.
• • Not have previously considered for the scholarship up to 3 times within the last 5 years.

Application instructions:

There is no separate scholarship application form, to be considered for the scholarship you must submit an application for admission to your research degree. Scholarship applications are welcome through out the year but only available for both the March (Research Period 2) and July (Research Period 3).

It is important to read the selection process and Research Experience guide and visit the official website (link found below) to access the application form and for detailed information on how to apply for this scholarship.

Website:

Official Scholarship Website:http://sydney.edu.au/scholarships/prospective/international_postgraduate_scholarships.shtml#usi

PREVENTION AND CONTROL OF POLLUTION

PREVENTION AND CONTROL METHOD OF ENVIRONMENTAL POLLUTION
• Appropriate design and standards for the control of specific pollutants should be put in place
• There should be awareness campaign inform of information and communication, which means that health education should be directed to all members of the society
• There should be environmental regulation, codes, standard guidelines and laws to control pollution
• Agencies should be established by all tiers of government that will enforce set standards and regulations
• Environmental health assessment should be fully carried out as a major integral part of environmental impact assessment prior to the establishment of industries
• The environmental impact assessment report should be strictly implemented by all stakeholders
• There should be an effective mechanism in place as response to emergency cases of pollution
• Proper urban and regional planning of industrial areas i.e industries should be sited faraway from residential areas
• Industries should minimize the burning of fossil fuels or change to less polluting fuels
• Adequate ventilation at work places
• Industrial effluents should be adequately and properly treated before discharged into water
• Regular monitoring and detection of environmental pollution.
Techniques of Creating Environmental Awareness and Education
Environmental awareness needs to be created through formal and informal education to all sections of the society, because environment belongs to all. Techniques of creating environmental awareness include:
• Among students (through education): environmental education must be imparted to student’s right from childhood stage. Environmental education should be introduced as a subject at all stages including at college level
• Among the masses (through mass media): the media can play an important role to educate the masses on environmental issues through articles, environmental rallies, plantation campaigns, street plays, advertisement and Tv shows.
• Public representatives forums for members of parliament and legislators to discuss environmental problems faced by the country
• Research and development programmes for seeking solution to different environmental problems
• Training professionals like engineers, architect and other personnel in the industries
• Designing instrument and technologies which are environmentally friendly and motivating people to use it for certain sustainable growth
• Training legal experts to deal with environmental legislation protection and claims in case of violation of environmental laws
• Publication and distribution of environmental related resource materials in form of pamphlets or booklets published by ministry of environment
• Organizing training, refresher courses and workshops for in service teachers dealing with environmental education.
Ways of Empowering Civil Societies, NGOs and Community Members to Serve as Watchdogs against Environmental Pollution
• The academicians and technocrats should engage and educate members of the civil societies and NGOs on environmental education through workshops, public lectures, research and public enlightenment
• Influential member and leaders in the communities should support, co-operate and participate in NGOs and civil society activities on environmental protection
• National and multinational companies should support and collaborate with NGOs and civil societies in environmental campaign awareness
• Law enforcement agencies and judiciary should assist the NGOs and civil societies in seeing to it that all establishments, agencies and individuals that run foul of the laws of the country on environmental protection are promptly apprehended and sanction as appropriate
• The legislature should co-operate with the NGOs and civil societies in passing appropriate laws that will regulate the management of environment in Nigeria
• NGOs and civil societies should in occasional programs discuss on environmental related issues in the electronic media as a means of informing and educating people
• NGOs and civil societies should be recognised by government for taking special interest in prevention of environmental pollution
• Students and members of the community should be encouraged to join NGOs and civil society groups.
Ways of Involving Community Members in Pollution Prevention
• Creating awareness and sensitizing the community members
• Implementation of environmental restoration programmes through active involvement of the communities e.g fuel efficient stoves, afforestation, sanitation, water and soil conservation
• The environmental awareness and education programmes must motivate and prepare the community members for active participation
• The local community leader and decision makers must be involved in orientation, training, implementation and management of the programmes
• Enacting laws and making it compulsory on each member of the community to participate in environmental prevention activities
• Enlightening the community members on the danger and harmful effects of environmental pollution
• Waging relentless war and punishing any member of the community who violate environmental laws.
Agencies Involved in Pollution Control
International agencies include:
• United Nation Environmental Programme (UNEP)
• World Bank
• World Health Organization (WHO)
• Global Environmental Monitoring Systems (GEMS)
National/State Agencies includes:
• Federal Ministry of Environment
• State Ministry of Environment
• Ministry of Industries
• Environmental Health Department
Non-governmental Organization (NGO) include:
• Nigeria Conservation Foundation (NCF)
• Nigerian Environmental Study/ Action Team (NEST)
• Nigerian Environmental Society (NES)

YOBE STATE UNIVERSITY (YSU) POSTGRADUATE APPLICATE FORM

PUBLIC ANNOUNCEMENT ON THE COMMENCEMENT OF POSTGRADUATE STUDY PROGAMMES IN YOBE STATE UNIVERSITY, DAMATURU.

This is to inform all those who have previously applied for postgraduate study programmes (two years ago in 2015/2016 Academic Session) that the programmes will now commence in the 2017/2018 academic session in the following areas:-

1. Geography, M.Sc. & PhD
2. Chemistry, M.Sc. & PhD
3. Arabic, M.A. & PhD
4. Islamic studies, M.A & PhD
5. Educational Administration and Planning, M.Ed. & PhD
6. Guidance and counseling, M. Ed. & PhD
7. Educational psychology, M.Ed. & PhD
8. Postgraduate Diploma in Education, PGDE

In view of the above, all those who still wish to avail themselves of their applications should kindly visit the postgraduate school portal (www.pgschool.ysu.edu.ng) and express their interest so that their application will be processed against 2017/2018 academic session.

In addition, those who applied for courses other than aforementioned ones may wish to express interest of change of application from the programmes that they had earlier applied to any of the above mentioned programmes.

However, applicants who have no intention of applications may present their Bank Deposit Slip/Receipts of payment for the purchase of postgraduate Application Forms for refund to the Bursar, please.

Deadline for the expression of interest is one (1) week: from Monday, 30th October, 2017 to Tuesday, 7th November, 2017.

Signed:
ALH. UMAR GARBA MOHAMMED
Deputy Registrar/Secretary School of Postgraduate Studies.

CAUSES AND EFFECTS OF POLLUTION

INTRODUCTION
Human activities generate a tremendous amount of waste materials, these are discharged into various component which bring about pollution in the environment. The term ‘Pollution’ refers to the act of contaminating one’s environment by introducing certain hazardous contaminants that disturb the ecosystem and directly or indirectly affect the living organisms of that environment. Pollution can also be defined as the presence or introduction of a substance or contaminant into natural environment that cause adverse change.
Environmental pollution is the contamination of air, water and land in such a manner as to cause real or potential harm to human health or well being of animals, plants, soil and properties. The types of environmental pollution include air pollution, water pollution, soil pollution, and noise pollution e.t.c.
Pollution control is a term used in environmental management. It is the control of emissions and effluents into air, water or soil. Without control, the waste product from consumption, heating, agricultural, mining and manufacturing, transportation and other human activities whether they accumulate or disperse will degrade the environment. Pollution control practices includes recycling, reusing, reducing and preventing while pollution control devices include dust collection system, baghouses, cyclone, spray tower, sewage treatment e.t.c.
Causes of Pollution
The causes of pollution in the environment include technological, economic, social and natural causes e.t.c.
Technological Cause of Pollution
1. Industrial activities resulting from technological processes yield toxic gases and greenhouse gases, thereby polluting the environment.
2. A large amount of exhaust gas from automobiles leads to serious air pollution
3. Owing to the development of modern agricultural technology, farmers tend to use lots of chemical fertilizers and pesticides to increase yield, which severely poison the soil and underground water.
Natural Causes of Pollution
The natural causes of pollution include:
a) Dust
b) Natural radioactivity
c) Ozone and nitrogen
d) Micro-organisms such as bacteria, spores, moulds and fungi from plants and animals
e) Forest fire
f) Soil erosion
Economic Causes of Pollution
This is as result of activities that contribute to the growth and development of nature and human welfare. Economic causes include:
• Agricultural activities for food production
• Health care for human beings and animals
• Dwelling for settlement in cities or villages
• Transportation
• Energy for various direct human and industrial needs.
Social Causes of Pollution
This is as a result of human activities in physical environment which may originate from tradition, culture, religion or some old practices. Schools, television shows, radio, newspaper, friends and co-workers are all social causes of pollution.
Man-made Contribution to Environmental Pollution;
• Burning of fuel like coal, diesel, gasoline, kerosene, that contains nitrogen, sulphur dioxide and hydrocarbons by power plant
• Domestic burning of fuels e.g firewood, kerosene
• Unpleasant noise from machines, factories and sound system
• Automobile source in rural and urban areas from aircraft engine, cars and trains
• Industrial activities such as quarrying, grinding and milling, iron and steel, cement industries e.t.c
• Dumping of domestic and industrial sewage in seas, rivers and ocean e.t.c


Other sources of pollution include;
Commercial sources: burning of refuse at market dumps, garbage producing offensive odour, dumping of refuse directly into water bodies pollute stream and river water, chemical substances from commercial sources pollute soil.
Agricultural sources: clearing of land and burning of farm residues produce air pollution, application of fertilizer destroy the soil.
Municipal sources: municipals are cities or towns where people live. People generate waste in their day to day activities. Indiscriminate dumping of refuse on plots of land pollutes the soil, so also is the disposal of sewage from houses into water bodies.
Harmful Effect of Pollution on Physical, Social and Cultural Environment
The physical effects of pollution are those that we can see, but they include effects other than actual physical change. Air pollution damages a wide variety of materials. Burning of oil and coal produce sulphur dioxides, and when combined with other pollutants such as soot, smoke, lead and sulphur oxides particulates causes corrosion at a faster rate. These particulates damage structures and equipments.
The most serious result of pollution is its harmful biological effect on human health and on the food chain of animals, birds and marine lives. Pollution destroys vegetation that provides food and shelter. Pesticides, which include herbicides and insecticides, can damage crops, kill vegetation, poison birds, animals and fish.
The wide spread use of pollutants, such as oil, chemicals and fertilizers pollute water ways.
Effects of Pollution on Human Health
• Some pollutants cause irritation of the eyes, nose, throat and respiratory tract
• Lead particulate causes lead poisoning resulting in convulsion, coma and even death
• Industrial effluents results in the addition of poisonous chemicals such as arsenic, mercury, cadmium and lead which reach human body through contaminated food
• Spread of water borne diseases like typhoid, dysentery, cholera are health hazards arising from drinking of contaminated water
• Toxic chemicals in water can be harmful to human health
• Some pollutants are carcinogenic
• Noise pollution can cause psychological problem, dizziness and tiredness
• It increases heart beat and rate of respiration
Effects of Pollution on Soil and Vegetation
• Particulates that settles on plant leaves may interfere with gaseous exchange during photosynthesis and respiration
• It leads to stunted growth in plants
• Pollution cause chlorosis, bleaching and other colour change in plants
• Loss of economic value
• Bush burning kills soil microbes and destroy vegetation cover of the soil
• Oil spill and toxic wastes destroy soil ecosystems
• Air pollution like sulphur dioxides, hydrogen sulphides cause serious damage to plants
• Air pollution make plants vulnerable to diseases and pest
Effects of Pollution on Water and Animals
• Thermal pollution leads to death and migration of aquatic animals
• The pH of the aquatic environment can be changed by added acid from industrial effluents
• Industrial waste contain toxic chemicals and can be harmful to aquatic life
• Some organic chemicals can impart bad taste and odour to water
• Waste with high organic matter content increases the biochemical oxygen demand of water
• Spread of diseases to animals and aquatic lives
• Poisonous air pollutant when inhaled can lead to death of animals e.g London Smog of 1952 which led to death of many cattle
• When animals graze on polluted grasses and crops, they may develop fluorosis and other health problems that can damage vital organs in their body.

CORROSION AGENTS IN OIL AND GAS PIPELINES

CORROSION AGENTS IN OIL AND GAS PIPELINES
Pipelines play a very critical role in the transportation of oil and gas process because, crude oil and other petroleum resources moves through pipelines for atleast part of the route. After the crude oil is separated from natural gas, pipelines transport the oil to another carrier or directly to a refinery. Pipelines are indispensable in safe, reliable and efficient transportation of oil and gas. One of the key problems of the carrier pipeline systems in the oil and gas industry is the exposure of the pipes to corrosion failures caused by the interaction of pipe material and aggressive environments. According to statistics about 90% of all pipeline emergencies are due to corrosive processes. Protectives in use (means of electrochemical protection (ECP means), corrosion prevention chemicals (corrosion inhibitors), insulation materials etc) are mostly turned out to be inefficient. In this respect the acute problem of searching for alternative ways of upgrading the oil and gas pipeline systems in the industry is crucial, especially when transporting aggressive environments. The application of pipes made of high strength and corrosion resistant composite and fibre patterns (CFP) is considered to be an evidently advanced and upto date trend. The petroleum industry is gradually building increased acceptance of fibreglass reinforced plastic (FRP) materials, while some companies make extensive use of FRP pipe for onshore and offshore hydrocarbon gathering and transmission lines. A few companies have used FRP down hole tubing products. In offshore there is limited use of FRP products in secondary structure such as cable trays, walkways, railing and grating. Recent developments in the North Sea area have resulted in projected increased usage of GRP pipe for various  types of low pressure water service offshore.
With ever-increasing challenges in developing deep-water offshore structures for petroleum exploration and production, composite materials technology is expected to play a more important role in meeting the stringent requirements of cost effective operations and enabling the capability of petroleum technology and its supporting industries.
Composite materials offer substantial weight reduction, superior corrosion resistance, long fatigue life, outstanding vibration damping and energy absorption, and also unlimited potentials of innovative material and structural tailoring to meet desired performance requirements. Along with low maintenance, low total life cycle costs, ease of fabrication  and installation are some of the advantages of using fibre reinforced polymer pipes for onshore and offshore applications. Composite materials are structurally ideal and suitable for immediate and future deep water challenges. Coatings can be developed to reduce the rate  at which fire exposure can affect GRP pipe.
Current protective coating technology for oil and gas pipelines is recognised to have both technical and economical disadvantages. Many factors such as climate, temperature, physical state of fluid being transported, physical location,  properties of the substrate travelling through the pipeline, product flammability and rate of flow contribute to the complexity of  designing efficient pipeline coating formulations.  In addition, the position of the pipeline must be taken into consideration, if the pipeline is laid underwater, the coating must be formulated to provide long term terminal and external durability.
Unprotected FRP pipe made with epoxy resin systems will be consumed when exposed to fire but it is self extinguishing  when the flame is removed. Under continuous fire exposure and with water flowing through the pipe, it tends to degrade to a given level and then maintains that performance level. The movement of fluid inside the pipe remains cool (i.e FRP is a low conductor of heat) and gives an extinguishing effects.
The use of phenolic resin as the polymer matrix in fire is being investigated as a fire resistant non-mettalic pipe. The features provided by phenolic resins include low toxicity, flame spread and smoke developed indices. A recent technological breakthrough in this area will allow the use of this previously difficult material for fire resistant piping.
Corrosion is fast becoming one of the most critical threats in pipelines and pipeline systems. Uncontrolled corrosion will result in loss of pressure containment. Corrosion can also affect flow efficiency through increased friction on the pipe wall and the resulting debris can damage the pipeline and associated equipment, as well restrict flow and reduce capacity.
Corrosion Agents in Oil and Gas include:
Carbon dioxide – CO2
Hydrogen sulphide – H2S
Oxygen –O2
Chlorides – Cl
Water- H2O
Causes of Corrosion in the Oil and Gas Industries
CO2 corrosion: general metal loss due to the presence of co2 in the process field
H2S corrosion: localized metal cracking and corrosion due to presence of h2s in the process fluid.
Chlorides and bicarbonates- cracking in the metal due to the presence of stress and chlorides in the process fluid
Corrosion due to oxygen – oxidation and metal loss due to the contact of metal with oxygen in the process fluid.
Microbiologically induced corrosion- bacteria that induces corrosion particularly within h2s
Erosion abrasion) corrosion- corrosion due to the fluid flow and velocity within the pipe environments.
The objective of this research is to clarify the principles of development corrosion-resistant leak tight and strong GRP pipes for the natural gas and oil industry.

NEGATIVE IMPACTS OF MARIJUANA ON HUMAN HEALTH

Continuation of adverse effects of marijuana on human health;

D. Cell Metabolism

Information currently available for the effect of cannabis on cell physiology and metabolism is limited. Smoke from both cannabis and tobacco increased the size of cytoplasm, nuclei, and nucleoli along with an increase in DNA content of human lung cell explants. Mitotic abnormalities were also noted with an increase of 10 to 25% over those of controls. Combination of both smokes produced greater abnormalities than either one alone. Malignant cell transformation of hamster lung culture was observed after administration of both types of smoke. These findings suggest that cannabis smoke is harmful to lung cells in cultures and contributes to the development of premalignant and malignant lesions.

Cannabinoids may also interfere with the normal cell cycle. Experiments with protozoan, Tetrahymena, synchronized in culture, showed a reduction in growth rate during log phase and lengthening of the mean division time upon exposure of THC. Addition of THC to various human and animal cell cultures has been shown to decrease synthesis of DNA< RNA< and protein. The clinical implication of some of these findings is obscure, exposure to smoke from cannabis may be carcinogenic while  the changes in nucleic acid synthesis is specific for rapidly dividing cells, such as those of malignancies, might be useful therapeutically in their treatment.

E. Psychopathology

Cannabis may produce directly an acute panic reaction,  toxic delirium, acute paranoid state, or acute mania. It can directly evoke depressive or schizophrenic states, or  it can lead to sociopathy or even to "a motivational syndrome" is much less certain. The existence of specific cannabis psychosis, postulated for many years, is still not established. The fact that users of cannabis may have higher levels of various types of psychopathology does not infer a casual relationship.

Indeed, the evidence rather suggests that virtually every diagnosable psychiatric illness among cannabis users began before the first use of the drug. Use of alcohol and tobacco, as well as sexual experience and "acting-out" behaviour, usually antedated the use of cannabis. When the contributions of childhood misbehaviour, school behavioural problems, and associated use of other illicit drugs were taken into account, it was difficult to make a case for a deleterious effect of regular cannabis use. Thus, it seems likely that psychopathology may predispose to cannabis use rather than the other way around.

1. Acute panic reaction.

This adverse psychological consequence of cannabis use is probably the most frequent  among three users in one high school and one in five in another reported having anxiety, confusion, or other unpleasant effects from cannabis use. These unpleasant experiences were not always associated with unfamiliarity with the drug; some subjects experienced these adverse reactions after repeated use. The conventional wisdom, however, is that such acute panic reactions occur more commonly in relatively inexperienced users of cannabis, more commonly when the dose is larger than that to which users may have become accustomed, and more commonly in older users who may enter the drug state with a higher level of initial apprehension.

The acute panic reactions associated with cannabis are similar to those previously reported to be caused by hallucinogens. The subject is most concerned about losing control or even of losing mind or concentration. Reactions are usually self-limited and may respond to reassurance or "talking down"; in the case of cannabis use, sedatives are rarely required as the inherent sedative effect of the drug, following initial stimulation, often is adequate. Occasionally one may see a dissociative reaction, but this complication is readily reversible. Depersonalization may be more long-lasting and recurrent, somewhat akin to flashbacks.

2. Toxic delirium.

 High dose of cannabis may evoke a toxic delirium, manifested by marked memory impairment, confusion, and disorientation. The nonspecific adverse psychological effect is seen with many drugs, but the exact mechanism is not clear in the case of cannabis as it is in the case of Datura stramonium smoking, for instance, which produces potent anticholinergic actions. As high doses of any drug tend to prolong its action, delirium is self-limited and requires no specific treatment. Highly potent preparations of cannabis are not as readily available in North America as in other parts of the world, so these reactions are less commonly observed in the United States and Canada.

3. Acute paranoid states.

 In a laboratory setting, they are frequently encountered. Quite possibly the experimental setting creates a paranoid frame of reference to begin with. That this reaction is not peculiar to the laboratory is evident from reports in which it has been experienced in social settings. The illegal status of the drug might contribute in such instances, for while intoxicated, one might be more fearful of the consequences of getting caught.

Undoubtedly, the degree of paranoia of the individual is also an important determinant, so that this reaction may represent an interplay between both the settings in which the drug is taken as well as the personality traits of the user.

4. Psychosis

A variety of psychotic reactions have been ascribed to cannabis use. Two cases of manic reaction were reported in children who were repeatedly exposed to cannabis by adults; both require treatment with antipsychotic drugs but ultimately showed a full recovery. Hypomania, with persecutory delusions, auditory hallucinations, withdrawal, and thought disorder, was observed in four Jamaican subjects who had increased their use of marijuana. Twenty psychotic patients admitted to a mental hospital with high urinary cannabinoid levels were compared with 20 patients with no evidence of exposure to cannabis. The former group was more agitated and hypomanic but showed less affective flattening, auditory hallucinations, incoherence of speech, and hysteria than the 20 matched control patients. The cannabis patients improved considerably after a week, while the control patients were essentially unchanged (146). Thus, a self-limiting hypomanic-schizophrenic-like psychoses following marijuana has been documented.

Psychosis in a group of East Indian marijuana users were predominantly instances of toxic delirium, but those who had "schizoid" features became overtly schizophrenic during the period of intoxication (30). The aggravating effect of marijuana on pre-existing schizophrenia has been documented.

However, it is impossible to distinguish retrospectively those individuals who exhibited behavioural changes in association with marijuana smoking from those who did not.

A controversial clinical report of 13 adults with psychiatric disorder associated with the use of cannabis included some who had schizophrenic-like illness and one with depressive features. The majority of these subjects had only used cannabis, which was thought to be the major precipitant of their disorders. A similar report from South Sweden involved 11 patients observed over a 1-year period. None had previous psychosis or abused other drugs. A mixture of affective and schizophrenic-like symptoms, as well as confusion and pronounced aggressiveness was observed. The mental disturbances were self-limiting and rare.

It is impossible to think of any controlled trial that could be designed to detect adverse psychiatric effects from chronic use of a drug. Thus, clinical reports have long served as the surest way to detect adverse effects of both social and medically used drugs.

Chronic use of hashish among a group of military personnel was tolerated quite well. Panic reactions, toxic psychosis, and schizophrenic reactions were infrequent occurrences among the group of 720 smokers, except when hashish was used in conjunction with alcohol or other psychoactive drugs, rather 110 subjects who used the highest doses (over 50 g/month) developed a chronic intoxicated state characterized by apathy, dullness, lethargy, as well as impaired judgement, concentration, and memory.

The paranoid psychosis associated with long-term cannabis use was contrasted with paranoid schizophrenia in groups of 25 Indian patients with each syndrome. The cannabis psychosis was characterized by more bizarre behaviour, more violence and panic, an absence of schizophrenic thought disorder, and more insight than was seen in the clearly schizophrenic group. The psychosis with drug use cleared rapidly with hospitalization and antipsychotic drug treatment and relapsed only when drug use was resumed. If there is a true cannabis psychosis, this description is probably most accurate.

It would seem reasonable to assume that cannabis might unmask latent psychiatric disorders and that this action probably accounts for the great variety that has been described following its use. On the other hand, evidence for a specific type of psychosis associated with its use is still elusive. Hallucinogenic drugs have a similar property of unmasking latent illness, but a drug such as LSD, being much more disruptive to mental functioning than cannabis, is much more likely to precipitate a true psychosis or depression. Needless to say, use of cannabis should be discouraged (as would probably be the case with most socially used psychoactive drugs) in any patient with a history of prior emotional disorder.

5. Flashbacks

This curious phenomenon, in which events associated with drug use are suddenly thrust into consciousness in the no drugged state, has never been satisfactorily explained. It is most common with LSD and other similar hallucinogens but has been reported fairly often with cannabis use (reference). At first, it was thought that the phenomenon occurred only in subjects who had used LSD as well as cannabis, but more recent experience indicates that it occurs in those whose sole drug use is cannabis (153). One possibility is that flashbacks represent a kind of deja vu phenomenon. Another is that they are associated with recurrent paroxysmal seizure-like activity in the brain. The most unlikely possibility is that they are related to a persistent drug effect, they may occur after withdrawal from the last use of either LSD or cannabis, so that it is highly unlikely that any active drug could still be present in the body (reference). Furthermore, the interval between last drug use and the flashback is one in which the subject is perfectly lucid, for most part, the reactions are mild and require no specific treatment (reference).

6. Violence.

The myth dies hard that cannabis makes otherwise docile subjects violent. Virtually every experimental study of cannabis that has tried to measure violent or aggressive behaviour or thoughts during cannabis intoxication has come to the same conclusion; they are decreased rather than increased (reference). A study of 40 college students focussed specifically on this problem, comparing cannabis with alcohol. Expression of physical aggression was related to the quantity of alcohol taken, but not to any dose of THC (64). Similar findings have resulted from surveys (162). Aggressive and sexually assaultive behaviour in delinquent adolescents was more common following use of alcohol, even in those who also used cannabis (168). A review of the whole subject of cannabis and violence came to the consensus that cannabis does not precipitate violence in the vast majority of users (reference).

The possibility was entertained that a rare individual with some special predisposition to aggressive or violent behaviour may be triggered into expressing such behaviour under the influence of the drug (2).

7. Motivational syndrome

Whether chronic use of cannabis changes basic the personality of the user so that he or she becomes less impelled to work and to strive for success has been a vexing question. As with other questions concerning cannabis use, it is difficult to separate consequences from possible causes of drug use (reference). The demonstration of such a syndrome in field studies has generally been unsuccessful. Cannabis use among working men in Costa Rica did not impair to any detectable degree their ability to function (26). Much the same was found among Jamaican labourers. No signs of apathy, ineffectiveness, non-productiveness, or deficits in general motivation were found (38). Each of these approaches has been criticized on the basis that those surveyed were unskilled workers in whom subtle impairment might be difficult to detect (reference). However, a study of college students came to similar conclusions (117).

Little evidence was adduced that dropping out of college was associated with cannabis use. Family background, relationship with parents during high school, and social values were stronger forces than drug use. Thus, in subjects with moderate use patterns of cannabis, no evidence of the amotivational syndrome was detected (18). A similar survey of college students found no significant relationship between marijuana use and achievement, orientation, or actual performance (123).

Laboratory studies have provided only scant evidence for this concept. A Canadian study showed a decrease in productivity following the smoking of cannabis. The decreased building of stools was due to less time worked than lessened efficiency at work (122). Using an operant paradigm, volunteer subjects on a research ward worked less as their consumption of cannabis increased. The decreased work output might have been due to decreased ability to work rather than decreased motivation (119). The former possibility is not suggested by neuropsychological testing of long-term users. No generalized decrement was observed in adaptive abilities or cerebral functions (24). Similar results were found in members of a United States religious sect that relies on cannabis use. They showed no impairment of cognitive functions on a number of neuropsychological tests (150).

One cannot help being impressed by the fact that many promising youngsters change their goals in life drastically after entering the illicit drug culture, usually by way of cannabis. While it is clearly impossible to be certain that these changes were caused by the drug (one might equally argue that the use of drug followed the decision to change life style). The consequences are often sad (reference).

Moderate use of the drug does not seem to be associated with this outcome, but when drug use becomes a preoccupation, trouble may be in the offing (reference).

8. Residual psychomotor impairment

Almost any task, if it is made difficult enough or if enough dose of drug is given, can be shown to be impaired by acute administration of cannabis. More to the point is whether following chronic use impairment remains a problem. Experimental studies in rats suggest that it does, but such studies are always difficult to extrapolate to man (47). A comparison of 23 chronic users of bhang (equivalent to about 50 mg of THC daily for at least 5 years) with 11 nonusers revealed some evidence of impairment in the users. The latter had lower intelligence and memory quotients with lower scores on psychomotor tests (179). For whatever reasons, studies of cannabis done in India tend to show more evidence of impairment than those done elsewhere.

9. Brain damage.

The startling report of cerebral atrophy in ten young men who were chronic users of cannabis aroused a great deal of controversy (22). The subjects selected for the study were ones who had come to psychiatric and neurological attention, besides which they had used other drugs. Even the validity of the method of measuring atrophy by comparing pneumocephalograms of the patients with negative controls was questioned. A study in monkeys provided some support for this observation. After 2 to 3 months of heavy to moderate exposure to marijuana smoke, electrographic recording changes were noted in the septal region, hippocampus, and amygdala which persisted 1 to 8 months after smoke exposure stopped. Ultrastructure changes were seen in synapses, as well as destruction of rough endoplasmic reticulum and the presence of nuclear inclusion bodies. No such changes were observed in animals exposed to smoke from extracted cannabis (73).

The advent of computerized tomography reopened the question. Two studies using this technique have effectively refuted the original claim of brain atrophy. Nineteen men with long histories of heavy cannabis smoking were examined, and none was found to have brain atrophy as determined by this sensitive technique (101). A similar finding was noted in the other study (33). On the other hand, alcohol has long been thought to cause brain atrophy, but recent studies suggest that it may be partially reversible (23).

As brain atrophy from alcohol requires a substantial amount of use, it is possible that with longer exposure, heavy users of cannabis might show a similar pattern, but at present this seems unlikely.

F. Tolerance and Dependence

Tolerance to cannabis has long been suspected to occur during its continued use. Narrative accounts indicate that chronic users of the drug either show very little effect from moderate doses or require very large doses to produce characteristic intoxication. A pioneer study of subchronic administration of cannabis and synhexyl, a synthetic cannabinoid, suggests at best some degree of tolerance to the euphoriant actions (180). Yet it has only been in the past few years that tolerance to cannabis has been clearly documented experimentally.

The demonstration of tolerance in man was delayed by ethical restrictions on the amount of exposure permissible to human subjects. For instance, in an early study subjects were exposed only to a test dose of 20 mg of THC and then given the same doses or placebos repeated at bedtime for 4 more days, followed by the same THC dose as a challenge on the fifth day. Using such small doses and relatively infrequent intervals, it was impossible to show tolerance to the psychic effects of the drug, although the tolerance to the tachycardia and dizziness produced by the drug were evident (85).

Other early studies likewise suggested tolerance without definite proof.

Tolerance to both tachycardia and "high" was reported following 21 days of consecutive smoking of only one cigarette a day by experienced smokers. It was possible that these subjects may have already been tolerant to the drug (46). Another study, in which subjects smoked a cannabis cigarette containing 14 mg THC for 22 days, revealed a progressive decline in the increase of pulse rate following smoking, an increase in alpha rhythm on the electroencephalogram, and more decrement in the performance of short-term memory and reaction time tasks (49).

A number of other early studies provided less evidence of tolerance. Little evidence of tolerance to clinical effects of cannabis was found from daily smoking of marijuana cigarettes over a period of 10 to 28 days (51, 142).

Free choice of marijuana cigarette for 21 days also provided little evidence to support the concept of tolerance in man (165). Meanwhile, substantial evidence had accumulated that tolerance could be shown in various animal species, especially with high doses of THC given for prolonged periods.

Definite evidence of tolerance to the effects of THC in man was adduced only when it became permissible to use comparably large doses over longer periods of time. Subjects in one 30-day study were given high doses (70 to 210 mg/day) of THC around the clock. Tachycardia actually became bradycardia, and a progressive loss of "high" was noted (49). Similar tolerance to cannabis smoking was observed in a 64-day study in which at least one cigarette daily had to be smoked with smoking as desired later in the same day. Additionally, in this study tolerance developed to the respiratory depressant effect of THC (13).

The pattern that has emerged in man, therefore, is that tolerance is not a problem when the doses are small, or infrequent, or where the pattern of use of the drug is not prolonged. Tolerance only becomes a major factor with high, sustained, and prolonged use of the drug. It is interesting that no study in man or animals ever revealed any evidence for "reverse tolerance" or sensitization, such as had been reported in an early, rather naive clinical study of marijuana (176).

1. Cross-tolerance

THC has effects which in man somewhat resemble those of hallucinogens and strongly resemble those of alcohol, while in animals it slightly resembles morphine. No cross-tolerance to mescaline or lysergide (LSD) could be shown in rats (151). Rats tolerant to the effects of THC were also tolerant to ethyl alcohol, but when the situation was reversed, less tolerance to THC was seen in the alcohol-tolerant animals (127). Perhaps this difference in sequential tolerance is why THC has never become established as a treatment for alcohol withdrawal, despite some early clinical trials that suggested a favourable effect. Cross-tolerance between THC and morphine has been shown in rats using customary tests of analgesia (95).

2. Physical dependence.

Evidence from both animals and man indicates that physical dependence can be induced by abuse of THC. All monkeys given automatic injection doses of THC of 0.1 to 0.4 mg/kg showed abstinence signs when withdrawn.Whenmonkeys were allowed to self-administer the drug for 3 to 8 weeks, the majority had an abstinence syndrome when the drug was abruptly discontinued. the syndrome appeared approximately 12 h after the last administration and lasted about 5 days. it was characterized by irritability, aggressivity, tremors, yawning, photophobia, piloerection, and penile erections (95).

In man, a somewhat similar, though mild, withdrawal reaction was uncovered after abrupt cessation of doses of 30 mg of THC given every for 10 to 20 days. Subjects became irritable, had sleep disturbances, and had decreased appetite. Nausea, vomiting, and occasionally diarrhea were encountered. Sweating, salivation, and tremors were autonomic signs of abstinence (49).

Relatively few reports of spontaneous withdrawal reactions from suddenly stopping cannabis use have appeared, despite the extraordinary amount of the drug consumed, Five young persons experienced restlessness, abdominal cramps, nausea, sweating, increased pulse rate, and muscle aches when their supplies of cannabis were cut off. Symptoms persisted for 1 to 3 days (15). The rarity of reports of these reactions may reflect the fact that they are mild, and seldom is a user completely cut off from additional drug.

Cannabis would have been an exceptional centrally acting drug if tolerance/dependence were not one of its properties. The fact that tolerance was not strongly recognized as an effect of chronic use was due to the narrative nature of previous accounts of tolerance in man and the lack of systematic animal experimentation. Tolerance has now been proven for most of the actions of THC. It develops at varying rates for different actions, but it is rapidly reversible. large doses of THC are required over long time periods for tolerance to develop. As most social use of the drug does not meet those requirements, neither tolerance nor dependence has been a major issue in its social use.

G. Endocrine and Metabolic Effects

Changes in male sex hormones have been a source of controversy ever since the first report of a cannabinoid-induced decrease in serum testosterone level.

Decreased levels were associated with morphological abnormalities in sperm and with decreased sexual functioning (100). Such changes must require long-term exposure to cannabis, for subchronic studies in experimental subjects have generally failed to confirm these findings (118). During the first 4 weeks of a chronic administration study, no major changes in hormone levels were detected, but with subsequent exposure a decrease first occurred in luteinizing hormone (LH) followed by decreases in testosterone and follicle-stimulating hormone (FSH) (99). Testosterone synthesis by Leydig cells was decreased in rats, both by THC as well as by other cannabinoids (21). A similar finding had been reported earlier (57). A review of the literature on this subject concluded that no significant effect was found in regard to serum testosterone and that sperm production was decreased but without evidence of infertility. Ovulation was inhibited, and luteinizing hormone was decreased. Cannabinoids had no evidence of estrogenic activity, which had been postulated earlier (4).

The meaning of such changes in man is uncertain, as the hormone levels generally remained within the accepted limits of normal. Further, a single hormone level may not be truly representative of the prevailing levels of hormones that tend to be secreted episodically or which are subject to many extraneous influences.

Data on the effects of cannabis on the female reproductive system are sparse.

Preliminary unpublished data indicate that women who use cannabis 4 times a week or more have more anovulatory menstrual cycles than do nonusers of the same age, Animal work tends to support this observation. THC administered to rats suppressed the cyclic surge of LH secretion and of ovulation (11).

Gynecomastia has been thought to be a complication of cannabis use, especially when it was also possible to stimulate breast tissue development in rats with THC (72). Eleven soldiers with gynecomastia of unknown cause were matched with 11 others with similar characteristics except for gynecomastia. No difference in cannabis use was found between the two groups (27). Such a finding does not disprove the relationship between cannabis and gynecomastia. Indeed, if cannabis increases peripheral conversion of testosterone to estrogens, then it is possible that the increased estrogens could stimulate breast tissue in a few susceptible men. Increased estrogens might also account for some reports of diminution in sexual drive or in performance in men.

These endocrine changes may be of relatively little consequence in adults, but they could be of major importance in the prepubertal male who may use cannabis. At least one instance of pubertal arrest has been documented. A 16-year-old boy who had smoked marijuana since age 11 had short stature, no pubic hair, small testes and penis and low serum testosterone. After stopping smoking, growth resumed and serum testosterone reached the normal range (41).

As recent surveys of cannabis use indicate that some boys (and girls) may be exposed to it even as early as the prepubertal years, this question is of more than academic interest.

Although cannabis has been said in the past to cause hypoglycemia, this error has been pointed out in numerous studies. On the contrary, some subjects showed impaired glucose tolerance following experimentally administered i.v. doses of 6 mg of THC. Such a dose is probably greater than one generally attains from usual cigarettes but might be obtained from high-grade hashish.

The deterioration of glucose tolerance was accomplished by increased levels of plasma growth hormone, as well as by a normal plasma insulin response.

these findings suggested that growth hormone might be interfering with the action of insulin (83). A study in rabbits indicated that blood glucose was increased by single doses of THC but that this increase could be prevented by adrenalectomy. Increased release of epinephrine following THC was postulated as a possible cause for the hyperglycemia (70). Although large doses of THC might aggravate diabetes, the rarity of this phenomenon in clinical practice may be due to the lower doses of THC used socially or the development of tolerance to this specific pharmacological effect.

H. Lung Problems

Virtually all users of cannabis in North America take the drug by smoking. As inhaling any foreign material into the lung amy have adverse consequences, as is well proven in the case of tobacco, this mode of administration of cannabis might also be suspect. Smoking is most efficient method for administering the drug, due to the enormously high lipid solubility of THC.

The pulmonary surfactant is a perfect trap for THC which is then rapidly absorbed into the blood. the kinetics of the THC administered by smoking are similar to those of its i.v. administration.

Heavy use of hashish by soldiers produced a number of bronchopulmonary consequences, including chronic bronchitis, chronic cough, and mucosal changes of squamous metaplasia, a precancerous change (74). Although at first THC was thought to be a respiratory depressant, more careful studies indicated that it was when given p.o. in doses of 22.5 mg (14). thus, its use in any form by patients with impaired pulmonary function would be hazardous.

Young, healthy volunteer subjects in a chronic smoking experiment had pulmonary function tests before and after 47 to 59 days of daily smoking of approximately five marijuana cigarettes a day. Decreases were found in forced expiratory volume in 1 s, in maximal midexpiratory flow rate, in plethysmographic specific airway conductance, and in diffusing capacity.

Thus, very heavy marijuana smoking for 6 to 8 weeks caused mild but significant airway obstruction (161).

Quite possibly such dramatic early changes are not progressive with continued smoking (171). Compared with tobacco, cannabis smoking yields more residue ("tar"), but the amount of smoke inhaled is very likely to be considerably less. The study in which five cigarettes were consumed daily represented heavy use of the drug, compared with 20 to 40 tobacco cigarettes which might be consumed by a heavy tobacco smoker. Low values for specific airway conductance were found in marijuana smokers, a change not observed in tobacco smokers. This change indicates mild impairment of large airway function. No differences were found between marijuana smokers and nonsmokers in spirometric indices, closing volumes, or nitrogen concentrations between 750 and 1250 ml of expired air (159). Marijuana smoke inhibits pulmonary antibacterial defense systems, mainly alveolar macrophages, in a dose-dependent manner. The cytotoxin involved is not related to any psychoactive component (86). One would assume that marijuana smokers might be more susceptible to bacterial infections of the lung, yet such increased susceptibility has not been clinically documented.

The issue of damage to lungs from cannabis is somewhat confounded by the fact that many cannabis users also use tobacco. As yet, it is far easier to find pulmonary cripples from the abuse of tobacco than it is to find any evidence of clinically important pulmonary insufficiency from smoking of cannabis.

I. Cardiovascular Problems

Tachycardia, orthostatic hypotension, and increased blood concentrations of carboxyhemoglobin from cannabis smoking would undoubtedly have deleterious effects on persons with heart disease due to arteriosclerosis of the coronary arteries or congestive heart failure. Although a slight trend toward increased use by persons over age 30 years has been detected in recent epidemiological studies, it is unlikely that many persons with serious heart disease will be exposed to this hazard from cannabis use.

Tachycardia is a consequence of almost every acute dose of cannabis, although some degree of tolerance develops to this effect. Evidence suggests that it is mainly due to an inhibition of vagal tone (32). Increasing the heart rate and thereby cardiac work might be harmful to patients with angina pectoris or congestive heart failure. A direct test of the effects of marijuana smoking in exercise-induced angina proved this harmful effect of the drug. Smoking one cigarette containing 19 mg of THC decreased the exercise time until angina by 48%. Smoking a marijuana placebo cigarette decreased the exercise time until angina by only 9%.thus, smoking marijuana increased myocardial oxygen demand and decreased myocardial oxygen delivery (9). A subsequent study compared the effect of this type of marijuana cigarette with that of a high nicotine cigarette. The marijuana cigarette decreased the exercise time by 50%; the nicotine cigarette decreased the exercise time to angina by 23% (10). Clearly, smoking of any kind is bad for patients with angina, but the greater effect of cannabis in increasing heart rate makes this drug especially bad for such patients. Fortunately, few angina patients are devotees of cannabis.

A rapid heart rate might be expected to aggravate congestive heart failure.

Actually, little is known about the direct effects of THC on myocardium. A single study using an isolated rat heart reported a negative inotropic effect from THC, i.e., weaker contractibility of muscle (115). If so, the use of cannabis by patients in congestive heart failure could make matters even worse.

Premature ventricular contractions have been reported following marijuana smoking (91). However, when subjects were continually monitored electrocardiographically while smoking cigarettes containing approximately 20 mg of THC, no increase in such premature beats was found (145). Ventricular premature beats are rarely observed and do not seem to be of any great clinical importance.

J. Eye Problems

Eye complaints of cannabis users are vague and mild. All 350 cannabis users had some eye complaints. Several consistent findings were (a) photophobia and belpharospasms; (b) injection of the globe; (c) increased visibility of the corneal nerves; and (d) accommodative or refractive changes. Visual acuity was preserved, but pupillary reactions were sluggish. Both alcohol and cannabis produced a moderately debilitating effects on lateral phoria and abduction. During smoking, lacrimation may be observed along with the characteristic marked conjunctival injection. Despite the fact that numerous and complex changes occur in the eyes of cannabis users, these effects are confined to the anterior segment and in most respects mimic an irrelative process of that region. they are transient and not cumulative. the are probably of little clinical significance (60).

Reduction intraocular pressure is a characteristic effect from cannabis. this action provides distinct therapeutic possibilities and will be discussed later.

K. Contamination of Cannabis

The most definite health hazard was contamination of cannabis, largely of Mexican origin, by the herbicide parquet. Inhalation of toxic amounts of this material could lead to severe lung damage, and some instances of acute toxicity have occurred. Paradoxically, this hazard stemmed from efforts to save cannabis users from less well-documented hazards to their health.

Estimates of the amount of contaminated cannabis reaching North America may have been grossly exaggerated due to false positive results in testing for paraquat. Formerly as much as one-third to one-half of Mexican cannabis was assumed to be contaminated. the results of later analyses suggest that only about 10% is contaminated. the problem still remains for the users as to how to identify such a contaminated product.

One thought has been to look for red spots on the marijuana leaves. this approach may be difficult for the leaves are usually available in a finely ground form. A red fluorescence is seen under ultraviolet light, such as is commonly used in discotheques. A similar red fluorescence may be seen on the lips of the smoker of paraquat contaminated cannabis.

After the experience with paraquat in Mexico, its use was temporarily discontinued. Recently, the possibility that it may be used against cannabis crops in California and Hawaii has surfaced. One would hope that over-zealous law enforcement would not once again pose a serious health risk to marijuana users.

Cannabis is generally harvested like any other crop. The final product of ground leaves and stems look very much like grass cut by a mower. usual insecticides and fungicides are rarely used, as the plant grows abundantly with minimal care. Other sources of contamination may include insects and fungi.

L. Possible Accumulation of Drug

The major if not sole active component of cannabis, THC, is highly lipid soluble. As the human body has a high lipid content, which includes not only body fat, but also brain and most cell membranes, lipid-soluble drugs tend to leave the blood rapidly to be distributed to fatty tissues. It is characteristic of such drugs that the action of a single dose is terminated not by the elimination of the drug through metabolic processes, but by redistribution to sites in the body where it cannot act. The prime example of such a drug is pentothal sodium, which rapidly produces anesthesia when given i.v. but which has a very short span of action. the drug still remains in the body, but in places where it cannot act. A similar situation applies to the widely used sedative drug, diazepam.

An early study of the pharmacokinetics of THC examined its tissue distribution following a single injection of radiolabeled material, the concentration of THC in fat was 10 times greater than for any other tissue examined and persisted in this tissue for 2 weeks. Thus, there is good evidence that THC and its metabolites might accumulate not only in fat, but also in brain (107).

Obviously, similar studies could not be done in man. One can measure in man the extraction of cannabis metabolites following single or repeated doses, to get some idea of their persistence. Following both single and repeated doses (at least single doses for several days), metabolites of cannabis of cannabis can be found in urine for varying periods, up to several days following the last dose (94). All of these metabolites are ones that are known to have no mental effects, except for a minuscule amount of unchanged THC which is excreted during the first 4 h following a dose, while the drug is having definite clinical effects. The excretion of these metabolites is not accompanied by any evidence of cannabis-like effects.

We may conjecture that THC rapidly leaves the blood to be sequestered in fatty tissues. It is either gradually metabolized in these tissues to inactive metabolites which are then excreted in the urine, or it may be gradually released from these tissues in small amounts to be metabolized by the liver before attaining effective plasma concentrations. In either case, there is no evidence of a continuing drug effect from this accumulation of drug in the body.

No one has yet reported on the excretion of metabolites following prolonged exceedingly high dose administration of THC. In one study in which doses of up to 210 mg of THC were given abrupt discontinuation of the drug led quickly to mild signs of a withdrawal reaction (49). As the development of withdrawal reactions is contingent upon a rapid decline to the pint of absence of active drug in the body, one must assume that no accumulation of active drug occurred even under extreme circumstances.

In short, the apprehension about accumulation of THC from repeated use is based on evidence indicating only the accumulation of drug that is either in inactive form to begin with or which is rendered inactive before reaching the circulation in any pharmacologically active amount. We do not know the full toxicity of many of the possible metabolites which might accumulate, but generally toxicity studies of cannabis and its constituents lead to the inescapable conclusion that it is one of the safest drugs ever studied this way.

M. Effects on Driving an Automobile

If marijuana is to become an accepted social drug, it would be important to know its effects on driving ability. Fully one-half of the fatal car crashes in the United States are associated with another social drug, alcohol.

Neither experimental nor epidemiological approaches to the marijuana question have yet provided definitive answers.

Many studies have used acute doses of marijuana or THC to study various psychomotor functions. these can be summarized by saying that, if the dose of drug was high enough or the task difficult enough, impairments were shown. It is difficult to determine how pertinent these tests are to the actual driving of an automobile. Furthermore, it is difficult to relate the effects of acute consumption of marijuana, often in relatively naive subjects, to effects that may be found in chronic users, who may have developed some degree of tolerance.

Studies on the acute effects of marijuana on simulated driving have shown mixed results. the first compared smoked marijuana (doses uncertain) with ethanol in sufficient quantities to produce alcohol levels of 100 mg/dl.

Marijuana increased speedometer errors but produced no deviation from the norm on accelerator, brake, signal, steering, or total errors. Alcohol had a far more deleterious effect (43).

12 and 16 mg was compared with a dose of 70 g of alcohol in eight volunteer subjects performing a simulated driving task. Both marijuana and alcohol increased the time to brake and to start, but these changes were confined to the 16 mg dose of THC (138). Marijuana was smoked with the intention of administering doses of 0, 50, 100, and 200 *g/kg, a most dubious assumption.

No significant deviations from the norm were noted in car control and tracking aspects (124).

Actual driving in normal traffic situations would more closely mimic real-life situations, including the dangers. Sixty-four volunteer subjects smoked cigarettes containing 0, 4.9, or 8.4 mg of THC. Oddly enough, THC had a biphasic effect, causing deterioration of driving skills in some subjects and improvement in others. A recently completed study compared the effects of smoking a marijuana cigarette with or without alcohol, alcohol alone, and placebos for each drug. Actual driving was done over a course rigged with various traffic problems. Both drugs produced impairment of driving performance, the combination being worse than either alone (141).

Fifty-nine subjects smoked marijuana cigarettes until "high" and then were periodically tested by highway patrol officers on the roadside sobriety test.

Overall, 94% of the subjects failed to pass the test 90 min after smoking and 60% after 150 min, despite the fact that by then plasma concentrations of THC were rather low (81). It appeared that establishing a clear relation between THC plasma concentrations and the degree of clinical impairment will be much more difficult than has been found in the case of alcohol (140). The exact prevalence of persons who might be picked up while driving under the influence of marijuana is uncertain. One survey found at least 5mg of THC per ml in blood specimens of 14.4% of a random sample of 1792 drivers detained for erratic driving. Many were associated with blood levels of alcohol as well (184).

Flying an airplane is much more difficult than driving an automobile, but the general principle of impairment are similar. Ten certified pilots who smoked marijuana or placebo were tested on a simulator. The results were highly variable from pilot to pilot and from skill to skill. It was assumed that the pilots had regained full function after 4 h (90). Somewhat contrary results were obtained in another similar study which found, however, some degree of impairment in flying skills as long as 24 h after an exposure to marijuana.

The subjects were unaware of any such impairment (182).

The issue is not clearly settled, but common sense would suggest that it would be unwise to try to drive an automobile soon after exposure to marijuana. In our first study with the drug, the subjects were asked during the period of their intoxication, "Would you be able to drive a car now?" Their uniform answer was, "You've got to be kidding." The biggest areas of doubt are how long the impairment, even though subtle, may last and how to deal forensically with driving while under the influence of marijuana. the best evidence at present would be to assume that any amount of THC more than 10 mg/ml in plasma is presumptive evidence of impairment. such a decision is arbitrary, but so have been forensic decisions about the presumed level of intoxication with alcohol.

IV. Therapeutic Uses

For many centuries, cannabis was used as a treatment, but only during the 19th century did a particularly lively interest develop for exploiting its therapeutic potential. Cannabis was reported to be effective in treating tetanus, convulsive disorders, neuralgia, migraine, dysmenorrhea, post partum psychoses, senile insomnia, depression, and gonorrhea, as well as opium or chloral hydrate addiction. In addition, it was used to stimulate appetite and to allay the pain and anxiety of patients terminally ill with cancer (64, 121). However, the advent of modern pharmacology beginning in the 20th century discovered many other drugs more definitely effective in these disorders, with a subsequent decrease in the enthusiasm for cannabis as a therapeutic agent.

Advances in the chemistry of cannabis during the 1940s established tetrahydrocannabinol (THC) as the major active component. A semisynthetic THC-like material, synhexyl, was tested as a therapeutic agent during the late 1940s and early 1950s. Initial trials reported efficacy as an antidepressant and as a treatment for alcohol or opiate withdrawal, but subsequent clinical evaluations were negative (156,166).

The exact structure of THC was shown in 1964 to be delta-9-trans-tetrahydrocannabinol, which was soon synthesized. The relative abundance of this material permitted extensive laboratory and clinical studies from 1968 onwards. These studies have included potential therapeutic uses.

At the present time, a number of pharmaceutical houses have programs to develop cannabinoids as therapeutic agents. The major problem is to separate the specific desired pharmacological effect from the pronounced mental effects of cannabinoids. A number of reviews of the potential therapeutic uses of cannabis have been published recently (36, 92, 104). We will now discuss some indications of current interest.

A antiemetic for Patients in Cancer Chemotherapy

Cancer chemotherapy, especially with the agent cisplatin, produces severe nausea and vomiting, which is extremely difficult to treat with ordinary antiemetic drugs, such as prochlorperazine. This complication is so severe that many patients forego effective cancer chemotherapy. The antiemetic effects of cannabis had been suggested as early as 1972 (6). THC was first tried as an antiemetic in a controlled trial comparing it with placebo in 20 patients undergoing cancer chemotherapy. Fifteen mg were given to some patients and 20 mg to the others in the form of gelatin capsules containing THC dissolved in sesame oil. The initial dose was started 2 h before chemotherapy and repeated 2 and 6 h later. Fourteen of the 20 patients in whom an evaluation could be made reported a definite antiemetic effect from THC, while none was observed from placebo during 22 courses of that drug (149).

Since then, studies have been largely confirmatory but not entirely so.

Fifty-three patients refractory to other treatments were studied in an uncontrolled fashion. Ten had complete control of vomiting when THC was administered prior to chemotherapy and for 24 h thereafter. Twenty-eight had 50% or more reduction in vomiting, and only 15 patients showed no therapeutic effect whatsoever. However, four patients were dropped from the study because of adverse effects (113). Fifteen doses of 15 mg of THC were compared with 10-mg doses of prochlorperazine in a controlled cross-over trial in 84 patients. THC produced complete response in 36 of 79 courses, while prochlorperazine was effective in only 16 of 76 courses. Twenty-five patients received both drugs, of whom 20 preferred THC. Of the 36 courses of THC that resulted in complete antiemetic response, 32 were associated with mental effects characterized as a "high" (148). Another comparison between THC in 15-mg doses and prochlorperazine in 10-mg doses versus a placebo control was made in 116 patients who received p.o. doses 3 times a day. The THC regimen was equal to prochlorperazine, and both were superior to placebo. However, many patients who received THC found it to be unpleasant (55). A comparison of THC with placebo was made in 15 patients with each patient acting as his or her control. Fourteen of the 15 patients given THC obtained more relief of nausea and vomiting than from placebo during a course of high-dose methotrexate chemotherapy (28). Best results were obtained when plasma concentrations of THC were more than 120 ng/ml. Such concentrations would ordinarily be expected to produce rather definite mental effects, THC was compared with two other antiemetics, thiethylperazine and metoclopramide, in a controlled cross-over trial. No difference was found between the antiemetic effect of these three agents. However, adverse effects of THC were sufficiently greater than those from the other two drugs, which raised questions about its clinical utility (37). When THC was compared with prochlorperazine and placebo, the latter two treatments were not found to differ, but THC was superior to either one (131).

In summary, it would appear that THC has definite antiemetic effects, that these are comparable to many other commonly used antiemetic agents such as prochlorperazine, thiethylperazine, and metoclopramide, but that the major disadvantage of the drug is the mental effects produced by the doses given.

A synthetic homolog of THC, nabilone, was developed in 1972 and has been tested extensively for antiemetic activity. Across-over study comparing nabilone with prochlorperazine in 113 patients revealed significantly greater response rates following nabilone therapy. However, side effects from nabilone were also more common (77). Although it was hoped that nabilone separated the antiemetic effects from the mental effects of THC, this goal was not fully achieved. Levonantradol and BRL 4664 are two other synthetic THC homologs which showed antiemetic effects in open studies (43, 154). The exact role of synthetic homologs of THC as antiemetic agents remains to be determined.

Currently, a large amount of data on the clinical use of THC as an antiemetic is being accumulated in therapeutic situations monitored by the Food and Drug Administration. Unfortunately, this massive amount of clinical experience has no control, so that it may be impossible to conclude more than what is already known. Meanwhile, extremely promising results have been obtained with larger than usual doses of metoclopramide. When this drug was compared with prochlorperazine and placebo, it was more effective than either, the only disturbing side effect being sedation (59). The doses used of metoclopramide were 1 mg/kg before treatment with cisplatin (perhaps the most emetic anticancer drug) and several times after treatment. Protection was total in 48% of courses and major in another 23% (157).

This experience with metoclopramide suggests that the whole issue of the antiemetic effects of THC may become moot, as there are other drugs such as domperidone, which may also be effective in this situation.

B. Glaucoma

Discovery of the ability of cannabis to lower intraocular pressure was more or less fortuitous. Intraocular pressure was measured as part of a multifaceted study of the effects of chronic smoking of large amounts of cannabis. Intraocular pressure was found to decrease as much as 45% in 9 of 11 subjects, 30 min after smoking (75). Lowered intraocular pressure lasted 4 to 5 h after smoking a single cigarette. Its magnitude was unrelated to the total number of cigarettes smoked. the maximal effect on intraocular pressure was produced by the amount of THC absorbed in a single cigarette containing 19 mg of THC. When patients with ocular hypertension or glaucoma were tested 7 of 11 showed a fall of intraocular pressure of 30%. Confirmatory evidence was obtained from a trial in which injection of THC in doses of 22 *g/kg and 44 *g/kg produced an average fall in intraocular pressure of 37%, with come decreases as much as 51% (40). Many experiments done in rabbits using various routes of administration, including instillation of cannabinoids into the eye, have confirmed the ability of cannabis to reduce intraocular pressure.

Topical administration would especially desirable for treating glaucoma as with other drugs used for this purpose. Smoking cannabis or taking THC would be totally unsuitable for patients with glaucoma. Rabbits have been used traditionally for studying eye medications. The lipid solubility of THC has been overcome by using mineral oil as the vehicle for its instillation into the eye. The degree of lowering of intraocular pressure is at least as great as that with conventional eye drops, such as pilocarpine, and the duration of effect is often longer. Some minimal systemic absorption of the drug occurs when it is applied to the conjunctivae, but it is of no consequence in producing mental effects. Other cannabinoids besides THC, such as cannabinol or 8-alpha- and 8-beta-11-dihydroxy-delta-9-THC, have also produced this effect in rabbits (62). These agents have no mental effects, which makes them of considerable interest for therapeutic use.

An extract of nonpsychoactive components of cannabis whose composition is still uncertain has been tested both alone and in combination with timolol eye drops in patients with increased intraocular pressure. The effects of the two agents are additive and are said to be effective when other measures have failed (177). BW 146Y, a synthetic THC homolog, has been given to glaucomatous patients. Unfortunately, mild orthostatic hypotension and subjective effects were noted in addition to reduced intraocular pressure (167).

No psychoactive component of cannabis can be considered as a feasible therapeutic agent in this situation. Intraocular pressures, although they are reduced acutely, have not been shown to be reduced following long-term treatment, nor has there been any demonstration that visual function is preserved by the use of cannabinoids in glaucoma. Some of the problems associated with the development of cannabinoids as treatment for glaucoma have already been cited (61). The exploitation of cannabinoids for treatment of glaucoma will require much further developmental work to ascertain which cannabinoid will be lastingly effective and well tolerated. The potential benefits could be great, as present-day glaucoma treatment still does not prevent blindness as often as it might. If the effects of cannabinoids are additive to those of other drugs, the overall benefit to patients may be greater than is currently possible with single drugs.

C. Analgesia

Smoking of material estimated to deliver 12 mg of THC increased sensitivity to an electric shock applied to the skin (78). Single doses of 10 mg and 20 mg of THC were compared with codeine (60 mg and 120 mg) in patients with cancer pain. A 20 mg dose of THC was comparable to both doses of codeine. The 10 mg dose, which was better tolerated, was less effective than either dose of codeine (129). THC given in doses of 44 *g/kg to patients undergoing dental extraction produced an analgesic effect, which was less than that achieved from doses of 157 *g of diazepam per kg,Several of these patients actually preferred placebo to the dose of 22 *g of THC per kg because of anxiety and dysphoria from the latter drug (139).

The apparent paradox is that THC both increases and decreases pain.

Traditionally, aspirin-like drugs, which work peripherally by inhibiting the synthesis of prostaglandins, are used to treat pain derived from the integument. The initial mental stimulation from THC might increase sensitivity to this kind of pain. Visceral pain, such as that of cancer patients, is usually treated by opiates, which have both peripheral and central sites of action. Recent evidence suggests that opiates may act directly on pain pathways in the spinal cord as well as reducing the effect that produces pain. Cannabis could conceivably modify the effective response.

Thus, when the two types of pain are distinguished from each other, the apparent paradox is solved.

THC, nantradol, and nabilone shared some properties with morphine in chronic spinal dog model. Latency of the skin twitch reflex was increased, and withdrawal abstinence was suppressed. Naltrexone did not antagonize these actions, suggesting that they are not mediated through opiate receptors (56).

Levonantradoli.m. was compared with placebo in postoperative pain, and a significant analgesic action was confirmed. No dose-response relationship was observed, and the number of side effects from levonantradol was rather high (89). It seems unlikely that any THC homolog will prove to be analgesic of choice, when one considers the present array of very effective new analgesics of the agonist-antagonist type. It is too early to be sure, however.

D. Muscle Relaxant

Patients with spinal cord injuries often self-treat their muscle spasticity by smoking cannabis. cannabis seems to help relieve the involuntary muscle spasms that can be so painful and disabling in this condition. A muscle relaxant or antispastic action of THC was confirmed by an experiment in which doses of 5 or 10 mg of THC were compared with placebo in patients with multiple sclerosis.The 10 mg dose of THC reduced spasticity by clinical measurement (135). Such single small studies can only point to the need for more study of this potential use of THC or possibly some of its homologs.

Diazepam, cyclobenzaprine, baclofen, and dantrolene, which are used as muscle relaxants, all have major limitations. A new sleetal muscle relaxant would be most welcome.

E. Anticonvulsant

One of the first therapeutic uses suggested for cannabis was as an anticonvulsant. Such an effect was documented experimentally many years ago (112). Subsequent studies in various animal species have validated this action. THC in cats temporarily reduced the clinical and electrographic seizure activity induced by electrical stimulation of subcortical structures (175). Mice were protected by cannabidiol against maximal electroshock seizures but not against those caused by pentylenetetrazole. Its profile of activity more resembled that of phenytoin than that of THC (170). THC and cannabidiol both potentiated the anticonvulsant effects of phenytoin against electrically induced seizures in mice. The two cannabinoids in combination produced the most effect (29). Kindling involves the once-daily application of initially subconvulsive electrical stimulation to culminate in generalized convulsive seizures. THC given chronically to rats prevented the kindling effect (174).

Clinical testing has been rare, despite all these various lines of evidence supporting an anticonvulsant effect of cannabinoids. Better control of seizures following regular marijuana smoking was reported in a not very convincing single case (39). Fifteen patients not adequately controlled by anticonvulsants were treated with additional cannabidiol in doses of 200 or 300 mg or placebo. Cannabidiol controlled seizures somewhat better that the addition of placebo (25). Cannabidiol has little if any psychoactivity, making it a good candidate for this use.

F. Bronchial Asthma

A general study of the effects of marijuana on respiration revealed a bronchodilating action in normal volunteer subjects. Marijuana smoke was calculated to deliver 85 or 32 *g of THC per kg. A fall of 38% in airway resistance and an increase of 44% in airway conductance occurred in the high-dose group. The low-dose group showed lesser changes, but they were still significant as compared with baseline. The sensitivity of the respiratory center to carbon dioxide was not altered by either dose, indicating no central respiratory depression (172).

Asthma was deliberately induced by either inhalation of methacholine or exercise in asthmatic patients. They were then treated with inhalation of placebo marijuana, of saline, of isoproterenol, or of smoke derived from marijuana containing 1 g of THC. Both marijuana smoke and isoproterenol aerosol effectively reversed both methacholine- and exercise-induced asthma, while saline and placebo marijuana had no effect (160). Aerosols of placebo-ethanol, of THC (200 *g) in ethanol, or of salbutamol (100 *g) were tested in another study of ten stable asthmatic patients. Forced expiratory volume in 1-s forced vital capacity, and peak flow rate were measured on each occasion. Both salbutamol and THC significantly improved ventilatory function. Improvement was more rapid with salbutamol, but the two treatments were equally effective at the end of 1 h (181).

Both delta-8 and delta-9-THC have bronchodilating effects, while neither cannabinol nor cannabidiol has such actions. Thus, this action resides only in the psychoactive material. No evidence of tolerance to this effect developed over 20 days of continual administration (58). The treatment of asthma is much more chronic; further studies of tolerance will be needed.

Some patients might experience bronchoconstriction following THC. Doses of 10 mg produced mild and inconsistent bronchodilator effects as well as significant nervous system effects. One patient of the six studied developed severe bronchial constriction (1). Mild but significant functional impairment, predominantly involving the large airways, was found in 74 regular smokers of cannabis. Such impairment was not detectable in individuals of the same age who regularly smoked tobacco (64).

THC would be best administered by aerosol for this purpose, but whether effective doses would avoid the mental effects is uncertain. The mechanism of action by which THC increases airway conductance may be different from the usual beta-adrenergic stimulants. Resistance to repeated applications of beta-adrenergic stimulants does occur. Another type of bronchodilator might help some patients. The recent introduction of highly effective steroid aerosols, such as beclomethasone, meets that need to a considerable extent.

G. Insomnia

THC does not differ from conventional hypnotics in reducing rapid eye movement (REM) sleep (136). THC in doses ranging from 61 to 258 *g/kg produces in normal subjects increments in stage 4 sleep and decrements in REM sleep, but without the characteristic REM rebound which follows chronic treatment with hypnotics. When THC was administered as a solution in doses of 10, 20, and 30 mg, our subjects fell asleep faster after having mood alterations consistent with a "high." Some degree of "hangover" the day following was noted from larger doses (42). Another sleep laboratory study showed that a dose of 20 mg of THC given decreased REM sleep. After four to six nights of use, abrupt discontinuation of THC produced mild insomnia but not marked REM rebound (52). REM rebound may not be apparent after low doses of THC. However, very high doses (70 to 210 mg) reduced REM sleep during treatment and were followed by marked REM rebound after withdrawal (48).

The sleep produced by THC does not seem to differ much from that of most currently used hypnotics. Side effects before sleep induction as well as hangover effects make the drug less acceptable than currently popular benzodiazepines. It seems unlikely that THC will supplant existing hypnotics in treatment of insomnia.

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