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The BCERF program on the Cancer Risks of Environmental Chemicals in the Home and Workplace closed on March 31, 2010. No further updates will be made to this web site. Please go Cornell University’s eCommons web site to access BCERF’s archived research and educational materials (

Interpreting Cancer Risk

Active ingredients

The EPA evaluates chemical carcinogenicity using data from many types of studies.

  • Most of the cancer risk information currently available is in the form of scientific results from studies of laboratory animals, such as rats or mice.
  • Other types of laboratory studies done at a smaller scale, such as individual cells, provide information about a chemical's ability to damage DNA or promote tumor growth.
  • Results from studies of groups of people exposed to certain chemicals, such as in the workplace or a community, may provide additional valuable information about a chemical's potential to cause cancer.

For many chemicals, however, no human data are available, so we must rely on data from laboratory and animal studies. Information on the species of laboratory animal tested, and the tumor types observed, provides some information about the extent to which the chemical may be carcinogenic. This information is just part of the total information EPA uses to estimate cancer risk. Other information from human studies and laboratory analyses is not currently available from EPA for use in the Turf Pesticides and Cancer Risk database.

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EPA's cancer risk classification systems and categories

In classifying the cancer risk of a particular chemical, EPA uses a combination of all of these types of evidence to arrive at a cancer risk category. EPA's cancer risk assessment methods have changed over the years to accommodate new scientific understanding. As a result, the four EPA cancer risk classification systems cannot be combined or used interchangeably due to the different methods used.

Pesticide products

Cancer risk categories do not apply directly to pesticide products. Rather, cancer risk information pertaining to the product's active ingredient(s) can be used in combination with other information to estimate potential risk.

  • Estimating the cancer-causing potential of a specific pesticide product involves many factors, such as the amount of active ingredient contained in the product, the application methods and rates used, proper use of personal protective equipment, and frequency and degree of exposure to the pesticide over time.
  • Current federal pesticide labeling laws require pesticide manufacturers to include only acute (short-term), and not chronic (long-term) health risk information on pesticide labels. Therefore, product-specific cancer risk information is not available.
  • Some states, such as California and Massachusetts, require that pesticides sold in those states carry labels specifying whether or not the product's active ingredients have been identified as health hazards, such as carcinogens, reproductive toxins, etc. Other states may include this information on their labels as well.
  • Current federal law requires that only active ingredients be listed on a pesticide product label. The names and health hazards of other substances in the product, called "inert" or "other" ingredients, are not required to be listed on the product label. Therefore, because this information is not publicly available, the cancer risks associated with inert / active ingredients contained in pesticide turf grass products could not be included in this database. Only cancer risk information on active ingredients is included.

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Using RED documents and other pesticide review information

Re-registration Eligibility Decision, or 'RED', documents are risk assessment reports done by EPA to determine whether or not to continue the registration of older pesticide products. Older pesticides (those first registered before 1984) must be re-evaluated by EPA to ensure that they meet current health and safety standards. RED documents are publicly available and are included in the Turf Pesticides and Cancer Risk database, providing valuable health risk information. There are many pesticides in need of re-evaluation, and not all can be done at once. The re-registration process will take years to complete. Those older pesticides whose uses include food crops have been given priority in this process.

Review of all pesticides is now done as part of the EPA's Registration Review process. This process, which took effect October 10, 2006, was established to ensure that all pesticides distributed and sold in the U.S. (not just older pesticides or those used on food crops) will be re-evaluated on a periodic basis to ensure they meet current health and safety standards. For more information, see Pesticide Registration. As pesticides are reviewed as part of this process, risk information will be added to the Turf Pesticides and Cancer Risk Database as it becomes available.

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