The Chemical World This Week
MARIJUANA: A WEAPON AGAINST CANCER? Aside from producing what some consider to be a desirable euphoria, marijuana cannabinoid derivatives also are showing promise as potentially useful, and nontoxic, treatments for various forms of cancer at least on the basis of tests with mice. In Montreal last week, pharmacologists from the Medical College of Virginia, Richmond, presented test results at a meeting of the American Society of Pharmacology and Experimental Therapeutics showing that at least one cannabinoid derivative, A 9 -tetrahydrocannabinol (THC), retarded the growth of lung cancers, breast cancers, and virus-induced leukemia in mice and prolonged the lives of the test animals by as much as 50%. The compound, and apparently other members of the cannabinoid family, also acts as an immunosuppressant, heading off the host's natural defense mechanisms that tend to reject such things as organ transplants and skin grafts. The MCV team, headed by pharmacology department chairman Louis S. Harris, became interested in cannabinoids following a report from Dr. Gabriel G. Nahas of Columbia University Medical Center, New York City, that habitual marijuana smoking suppresses the body's immune response and could make users unusually susceptible to disease. The MCV research scientists believe, as does Dr. Nahas, that the cannabinoids block tumor growth by inhibiting the deoxyribonucleic acid (DNA) synthesis necessary for cell reproduction. However, THC, or any of the other cannabinoids for that matter, does not destroy existing cancerous growths. All of the test animals in the MCV study eventually died from their cancers. As far as immunosuppressant activity is concerned, the scientists believe that cannabinoids decrease the reactivity of the lymphocytes that combat disease. Because of its immunosuppressant activity, THC and other cannabinoids may be useful in promoting the acceptance of organ transplants in humans. So far only one drug, 6-mercaptopurine (6-MP), has been found effective in preventing rejection of a transplanted organ, and only in one type of 6
C&EN August 26, 1974
ber of the MCV team, says that A 9 -THC does produce reversible bone marrow destruction in vitro. But the amount needed to produce 50% destruction is about 1000 times greater than is necessary for a 50% reduction in cancerous cell reproduction. The MCV findings and those of Columbia's Dr. Nahas, as well as results from other workers in cannabinoid chemistry, have stimulated much additional research. At least 10 papers dealing with cannabinoids as potential therapeutics Marijuana attracts additional research for a variety of disorders will be presented at the national meeting transplant—kidney. But 6-MP is of the American Chemical Society highly toxic even by drug standards in Atlantic City next month. and thus must be used with great The search for an effective cancer caution. A 9 -THC, on the other therapeutic alone could produce hand, has an LD50 in mice of about years of research work, since, as 1 gram per kg., making it relatively MCV's Dr. Carchman points out, nontoxic for a drug. there are hundreds of compounds THC is not without drawbacks. chemically related to THC that can Dr. Richard A. Carchman, a mem- be studied for antitumor activity.
ACS "clarifies" stance on vinyl chloride ACS Executive Director Robert W. I regard to the proposed standard." Cairns has forwarded to the Occu- At issue are two sentences in the pational Safety and Health Ad- ACS policy statement that Dr. ministration a "clarifying state- Cairns says are "inseparable." To ment" of the ACS position present- wit: "In the absence of data estabed at hearings early last month on lishing a safe level of exposure to the agency's proposed "no détecta- vinyl chloride and in the interests ble level" work-place standard of public health and welfare, the proposed for vinyl chloride. ACS's Society endorses the proposed stanposition was presented at the hear- dard for the level of employee expoings by Howard H. Fawcett, chair- sure. However, the Society believes man of the ACS Committee on that the standard for employee exChemical Safety, and Dr. Stephen posure would be clearer if set at a T. Quigley, head of ACS's depart- minimum practical level capable of ment of chemistry and public af- detection by a recommended methfairs. od rather than at no detectable The ACS clarification is included level." in a letter specifically responding to Dr. Cairns points out that "if eiquestions—such as requesting ther of these two sentences is taken membership lists of the ACS Board out of context an erroneous concluof Directors and certain other com- sion could be drawn relative to the mittees and a listing of human Society's position. It is clear from threshold limit values for several these two sentences that the Socichemicals—raised by the Labor De- ety does not endorse a 'no detectapartment solicitor on ACS's testi- ble level' standard for the level mony. of employee exposure." Therefore, In the midst of responding to Dr. Cairns adds, "we would like to these questions, Dr. Cairns points submit for the record the following out to OSHA administrative law clarifying statement as to what judge Gordon J. Myatt, who pre- these two sentences were intended sided over the hearings, that for the to state: In the absence of knowing record, "there has been consider- the tolerable limit for workers exable misunderstanding about what posed to vinyl chloride, the stanthe Society's position actually is in I dard should be set as low as can be
