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Chemicals Evaluated for Carcinogenic Potential

A number of years ago the EPA had on it's website a listing of chemicals and their rating for potential human carcinogenicity. That list was removed several years ago and was subsequently said to be available only as paper copy. The EPA revised it's human carcinogenicity classification scheme and produced a fourth iteration of a categorization system for ranking the human carcinogenic potential of chemicals (1999). Last month (July 2004) EPA once again produced a public listing of pesticide active ingredients with their rating in terms of their perceived ability to cause cancer in humans. It is now available as a PDF on the web (URL below)

EPA's 22 page document briefly discusses the history of EPA's efforts in determining potential carcinogenicity of pesticides and explains it's "new" (1999) classification system. It provides it's older systems (1976; 1986 - this one used letters and had five main categories; 1996 - this one had only three categories) with descriptors as a reference but notes that none are comparable. In it's newer (1999) system pesticide active ingredients, including those that are registered, submitted for registration, reregistration, or are in special review, are all classified (see the document for explanation of each category). The new categories are:

- Not likely to be carcinogenic to humans
- Data are inadequate for an assessment of human carcinogenic potential
- Suggestive evidence of carcinogenicity, but not sufficient to assess human carcinogenic potential
- Likely to be carcinogenic to humans
- Carcinogenic to humans

The first (barely) three pages of this document are a brief explanation / background of EPA's efforts at determining carcinogenicity in pesticides. Pages 4-6 are descriptors and definitions of the several classification systems EPA has used in reviewing pesticides. The list encompasses pages 7-21 of the document. Page 22 is two footnotes.

What makes this listing very complicated and somewhat frustrating is that the EPA uses several of it's systems - that is, the new (1999) system AND the 1986 and 1996 systems - in this one list. EPA leaves us to view the list noting (page 3) that the various systems are not comparable and that "The designation for any substance must be considered in the context of the system in which it was reviewed."

To help with the list,
- column one is the chemical name of the pesticide active ingredient [ref: ].

- The second column is it's CAS No. This is a numerical identifier for the chemical using the CAS chemical indentification system [ref: ].

- The third column, "PC Code" is the EPA Pesticide Chemical Code, their own substance identifier system [ref: ]

- Column four is the 'Cancer Classification', again, using multiple EPA classification schemes.

- The last, fifth, column is the EPA report that determined the carcinogenicity of the substance. OPP is the EPA Office of Pesticide Programs.

- Two footnotes help with what group reviewed the chemicals and with acronyms in the list.

EPA notes that it intends to keep the list updated.

Chemicals Evaluated for Carcinogenic Potential

Additional sites of interest:
Clemson University Pesticide Information Program

South Carolina Agromedicine Program (MUSC)

EPA Pesticides Health & Safety


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