Standard US EPA Cancer Classification
Standard US EPA classification (1986)
Standard EPA classification categorization descriptions
EPA cancer guidelines evolution (1986-2003)
Standard US EPA classification (1986)
Chemicals or other agents in the environment assessed by US EPA (Environmental Protection Agency) are classified in five groups based on the existing scientific evidence for carcinogenicity.
Group A: "Human Carcinogen"
There is enough evidence to conclude that it can cause cancer in humans.
EPA definition
Group B1: "Probable Human Carcinogen"
There is limited evidence that it can cause cancer in humans, but at present it is not conclusive.
EPA definition
Group B2: "Probable Human Carcinogen"
There is inadequate evidence that it can cause cancer in humans but at present it is far from conclusive.
EPA definition
Group C: "Possible Human Carcinogen"
There is limited evidence that it can cause cancer in animals in the absence of human data, but at present it is not conclusive.
EPA definition
Group D: "Not Classifiable as to Human Carcinogenicity"
There is no evidence at present that it causes cancer in humans.
EPA definition
Group E: "Evidence of Non-Carcinogenicity for Humans"
There is strong evidence that it does not cause cancer in humans.
EPA definition
Standard EPA classification categorization descriptions
Group A: "Human Carcinogen"
"This group is used only when there is sufficient evidence from epidemiologic studies to support a cusal association between exposure to the agents and cancer."
Group B (1 and 2): "Probable Human Carcinogen"
"This group includes agents for which the weight of evidence of human carcinogenicity based on epidemiologic studies is "limited" and also includes agents for which the weight of evidence of carcinogenicity based on animal studies is "sufficient". The group is divided into two subgroups. Usually, Group B1 is reserved for agents for which there is limited evidence of carcinogenicity from epidemiological studies. It is reasonable, for practical purposes, to regard an agent for which there is "sufficient evidence of carcinogenicity " in animals as if it presented a carcinogenic risk to humans. Therefore, agents for which there is "sufficient" evidence from animal studies and for which there is "inadequate evidence" or "no data" from epidemiologic studies would usually be categorized under Group B2."
Group C: "Possible Human Carcinogen"
"This group is used for agents with limited evidence of carcinogenicity in animals in the absence of human data. It includes a wide variety of evidence, e.g., (a) a malignant tumor response in a single well-conducted experiment that does not meet conditions for sufficient evidence, (b) tumor responses of marginal statistical significance in studies having inadequate design or reporting, (c) benign but not malignant tumors with an agent showing no response in a variety of short-term tests for mutagenicity, and (d) responses of marginal statistical significance in a tissue known to have a high or variable background rate."
Group D: "Not Classifiable as to Human Carcinogenicity"
"This group is generally used for agents with inadequate human and animal evidence of cercinogenicity or for which no data are available."
Group E: "Evidence of Non-Carcinogenicity for Humans"
"This group is used for agents that show no evidence for carcinogenicity in at least two adequate animal tests in different species or in both adequate epidemiologic and animal studies.
The designation of an agent as being in Group E is based on the available evidence and should not be interpreted as a definitive conclusion that the agent will not be a carcinogen under any circumstances."
Source: US EPA
EPA cancer guidelines evolution
EPA published final cancer guidelines in 1986. As with other risk assessment guidelines, EPA has been working to revise the cancer guidelines to reflect advances in scientific understanding as well as experience in using them. Listed below are EPA's initial cancer guidelines and draft revisions.
2003 Drafts:
2003 Draft Final Guidelines:
2003 Draft Supplemental Guidance:
Current Agency Guidance:
1999 Draft Revised Guidelines: