The Report on Carcinogens is mandated by Section 301 (b) (4) of the Public Health Services Act, as amended, which stipulates that the Secretary of the Department of Health and Human Services shall publish an annual report which contains:
In 1993 Public Law 95-622 was amended to change the frequency of publication from an annual to a biennial report. The Report on Carcinogens is issued in response to the above requirements and is for informational purposes only. These reports discuss individual substances, mixtures of chemicals, or exposure circumstances which are known to be human carcinogens or which may reasonably be anticipated to be human carcinogens; they also contain information received from other Federal agencies relating to estimated exposures and exposure standards or guidelines.
The Report on Carcinogens contains a list of substances that may pose a potential hazard to human health. The Reports are informational scientific and public health documents. They serve as meaningful compilations of 1) the cancer data available for the listed substances in humans and/or animals, 2) on the potential for exposure to these substances, and 3) on the regulations required by Federal agencies to limit exposures to these substances or exposure circumstances. The Reports do not present risk assessments of cancer potential. The listing of a substance in the Report, therefore, does not establish that such substances or exposure circumstances presents a risk to persons in their daily lives. Such formal risk assessments are the responsibility of the appropriate Federal, State, and local health regulatory and research agencies.
It is also important to note that these listings do not address potential benefits of exposures to certain carcinogenic substances in special situations. For example, numerous drugs that are part of typical cancer chemotherapeutic programs have been shown to increase the frequency of secondary cancers in patients undergoing chemotherapy. In these instances, the benefits of exposure to the substance or exposure circumstance may well far outweigh the risks caused by such exposures and personal decisions concerning voluntary exposures to cancer causing agents need to be based, at least in part, on information that is beyond the scope of this document.
The evaluation of substances listed in the Report is performed by scientists from the National Toxicology Program, other Federal health research and regulatory agencies, and non government institutions. The listings in the Report identifies a substance or exposure circumstance as a known or reasonably anticipated human carcinogen and represents an initial step in hazard identification, which is generally considered the first step in the analytical process known as risk assessment. It is necessary to conduct a risk assessment in order to estimate the potential for any substance to harm human health. Risk assessments are not conducted by the National Toxicology Program for substances or exposure circumstances listed in the Report.
For the purpose of this Report, known to be human carcinogens are defined as those substances for which there is sufficient evidence of carcinogenicity from human studies that indicates a causal relationship between exposure to the agent, substance, mixture or exposure circumstance and human cancer. Human studies are defined as human epidemiology studies and/or experimental studies of human tissues or cells. These experimental studies could include metabolic and toxicokinetic considerations as well as evidence of genetic damage, DNA binding, or persistence of DNA lesions in exposed humans. Reasonably anticipated to be human carcinogens are those substances for which there is limited evidence of carcinogenicity in humans and/or sufficient evidence of carcinogenicity in experimental animals. Sufficient evidence in animals is demonstrated by positive carcinogenicity findings in multiple species, or at multiple tissue sites, or by multiple routes of exposure, or to an unusual degree with regard to incidence, site or type of tumor or age at onset. There may be substances for which there is less than sufficient evidence of carcinogenicity in humans or laboratory animals but for which there are compelling data indicating that the substance could cause cancer in humans. Conversely, there may be substances for which there is evidence of carcinogenicity in laboratory animals but there are compelling data indicating that the agent acts through mechanisms which do not operate in humans and would therefore not reasonably be anticipated to cause cancer in humans. Conclusions regarding carcinogenicity in humans or experimental animals are based on scientific judgment, with consideration given to all relevant information. Relevant information includes, but is not limited to dose response, route of exposure, chemical structure, metabolism, pharmacokinetics, sensitive sub populations, genetic effects or other data relating to mechanism of action, and/or factors that may be unique to a given substance or exposure circumstance.