I assume you have the 2/18/98 Federal Register EPA "Final Rule"
setting tolerances for dimethomorph. The review of the tox data package is
pretty complete. It is not as fully tested as most would like, but as a new
chemical, there is a lot of data, and 2-generation repro. studies reviewed.
Get it via EPA site, to Fed. Reg, to 1998, to Feb., to the 18th.
For other Saneters -- the best way to get human tox data on new
pesticides is to search the Fed. Reg. database on the EPA site and look for
notices of applicaitons for new registrations; or tolerance petitions; or
section 18 requests. Post passage of the FQPA, EPA is now required to carry
out a complete tolerance assessment before granting a tolerance for a
section 18 request. So section 18 documents have pretty complete reviews of
the tox databases, including discussion of the basis for setting the RfD,
which for dimethomorph is 0.01 mg/kg based on a 2-year chronic rat study,
and a 1,000 uncertainty factor -- 10-fold higher than normal because of FQPA
requirements to protect infants and children. Based on this reference dose
and safety factor, dimethomorph is clearly down in the "not very toxic"
range of active ingredients. Relatively hot/toxic a.i.'s have reference
doses less than 0.001. There still may be some endocrine or other low-dose
effects with dimethomorph that current EPA testing protocols do not detect
-- the reason the FQPA requires development/application of a new set of
endocrine assays, and a developmental neurotoxicity study (in most cases, we
suspect), along with an extra 10-fold safety factor in the absence of
complete tox and exposure data to support an EPA judgement that a proposed
tolerance level is protective of ingfants and children.
Chuck
Charles Benbrook 208-263-5236 (voice)
Benbrook Consulting Services 208-263-7342 (fax)
5085 Upper Pack River Road benbrook@hillnet.com [e-mail]
Sandpoint, Idaho 83864 http://www.pmac.net
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