A chemical is designated as a known or suspected carcinogen by the International Agency for Research on Cancer (IARC) or by the US National Toxicology Program (NTP). A chemical (and its compounds) is included if the chemical or any of its compounds is a designated carcinogen because the chemical and its compounds are reported as one category of substance in the PRTRs.
The group of chemicals classified as toxic under the Canadian Environmental Protection Act (CEPA) of 1999. In Canada, chemicals are assessed to identify which ones can pose a risk to the environment or human life and health. To be classified as "toxic" under CEPA, a chemical is entering or may enter the environment in a quantity or concentration or under conditions that:
1) have or may have an immediate or long term harmful effect on the environment or biological diversity,
2) constitute or may constitute a danger to the environment on which life depends, or
3) constitute or may constitute a danger to human life or health.
Once a chemical has been classified as toxic, it is usually placed on Schedule 1, which then gives the federal government authority to regulate the chemical. The federal government has two years to develop preventative or control measures for toxic chemicals and a further 18 months to finalize the measures.
The group of chemicals that are on the California Proposition 65 list. In 1986, California voters approved an initiative (Proposition 65 on the ballot) to address the growing concerns about exposures to toxic chemicals. The subsequent act (The Safe Drinking Water and Toxic Enforcement Act of 1986) requires the Governor of California to publish a list of chemicals that are known to the state of California to cause cancer, birth defects or other reproductive harm. The list is updated at least once a year. The full list can be found on the Internet at www.oehha.org/prop65.html.
In order to provide information beyond the total amount of a chemical release, the Taking Stock report includes a chemical ranking system that takes into account both a chemicals toxicity and its potential for human exposure.
Toxic Equivalency Potentials (TEPs) indicate the relative human health risk associated with a release of one unit of chemical, compared to the risk posed by the release of one unit of a reference chemical. The reference chemical for carcinogens is benzene and the reference chemical for recognized developmental and reproductive toxicants is toluene.
TEPs provide a chemical ranking system that takes into account both a chemicals toxicity and its potential for human exposure and depend on the chemical as well as the medium of exposure. TEPs use in Taking Stock include a TEP for carcinogens for air releases and for surface water releases. Separate TEPs for recognized developmental and reproductive toxicants are used, again, for air releases and for surface water releases. The TEP is multiplied by the amount of release and the result is used to rank the chemicals. If there is no TEP for the particular release, it is noted and no rank is given.
The TEP approach was developed by scientists at the University of California at Berkeley, and reviewed by the US EPA Science Advisory Board. These TEPs are from Scorecard and take into both a chemicals toxicity and its potential for human exposure. However, this analysis is limited in that a release does not directly correlate to actual exposures. As such, the findings of these analyses do not necessarily equate to levels of risk. In addition, not all of the chemicals have a TEP available (information on their toxicity or exposure potential may be missing). While these chemicals are not ranked on TEP, they should not be assumed to be without risk. Also, TEPs for land releases are not available; therefore, some potentially high hazard chemicals with these types of releases will not be ranked by TEP.
TEPs will be seen whenever a Chemical report is chosen in Step 1 and air releases and/or water releases are selected in Step 4 (Select the media) below.