CPSC Cancer Study Suggests New Potential Risks

The conclusions of a $700,000 cancer study conducted for the Consumer Product Safety Commission indicate for the first time that inhaling a single high dose of a known carcinogen may cause cancer in animals.

The study findings, which are preliminary and currently undergoing review by other government cancer experts, were the result of more than four years of testing and analysis of the effects on animals of high doses of the chemical vinyl chloride. These findings were discussed earlier this month during a meeting of the federal government's Interagency Collaborative Group on Environmental Carcinogenesis.

During the testing, vinyl chloride monomer (VCM) was administered in single and multiple doses to laboratory rats and mice as part of a lifetime cancer study and a multi-generation reproduction study. Doses of VCM in the form of a gas were inhaled by the lab animals.

The study concluded that the carcinogenic effects of VCM depend upon concentration and exposure time, and, most importantly, that single (one-hour) exposures at high dose levels (50,000 ppm and 5,000 ppm) of this known carcinogen can produce tumors in laboratory mice. Previous cancer research has focused almost exclusively on the effects of repeated low-level and high-level exposures to carcinogens over lengthy time periods.

Dr. Joseph McLaughlin, Jr., the project supervisor for CPSC, said the study is the first to assess the effects of such short term exposure. Vinyl chloride was chosen as the most appropriate chemical for the CPSC study because much already had been learned about the chemical's carcinogenic effects on animals and humans through previous tests and studies.

The VCM study, which began in early 1975, was conducted by Dr. Bernard McNamara and his staff at the Chemical Systems Laboratory (formerly the Edgewood Arsenal at the Aberdeen Proving Grounds in northeastern Maryland). Following the one-hour exposures to the high doses of VCM gas, the laboratory mice and rats were allowed to live their normal life span and then were sacrificed and examined in pathological analysis for evidence of tumors. Pulmonary tumors, both adenoma (benign) and carcinoma (malignant), were common in the mice which had been subjected to single high level doses (50,000 ppm and 5,000 ppm) of VCM.

The test conclusions showed tumors in the mace only (and not in the lab rats). The VCM reproduction study conducted simultaneously did not demonstrate mutagenic or teratogenic effects in generations of the laboratory animals.

The conclusions of the CPSC study suggest that further short-term high-dose studies of other known carcinogens may be appropriate for government and private researchers.

Until several years ago, vinyl chloride was used in a variety of products, primarily as a propellant in aerosol products, ranging from spray paints and solvents to hairsprays and pesticides. Medical studies of workers in the early 1970's which associated vinyl chloride exposure with a rare form of liver cancer (angiosarcoma) resulted in a commercial ban on the chemical by several federal government agencies in 1974.

CPSC banned consumer product aerosols, such as spray paints, containing vinyl chloride monomer as a propellant or an ingredient. The Food and Drug Administration banned VCM from hairsprays and cosmetics, and the EPA banned the chemical from use in pesticides. OSHA also established restricted workplace exposure levels for VCM, which still iS used by various U.S. industries to produce polyvinyl chloride, a plastic in widespread use.

The study's findings further support the thesis that a single exposure to a high dose of VCM, or perhaps other similarly acting carcinogens, could pose a risk of cancer to humans. This suggests that a one-time exposure occurring, for example, as a result of an accidental spillage of VCM on the nation's highways, railways, or waterways, could threaten workers at the spillage site, public safety personnel, and perhaps even nearby residents.

Scientific review of the study and its conclusions will facilitate the assessment of the regulatory impact of the VCM study on various government agencies. This review and eventual publication of the study in medical publications also is expected to stimulate further research in other health areas by governmental, industry and academic experts.

Scientists and members of the press who wish to receive copies of the draft summary report of the Commission's VCM inhalation study should write to CPSC's Office of the Secretary, Room 300, 1111 18th Street, N. W., Washington, D.C. 20207. The telephone number for the Office of the Secretary is (202) 634-7700. (For further information, contact John Bell, CPSC Director of Media Relations, 634-7780).