Carcinogenic Action of Pesticides
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Carcinogenic Action of Pesticides
Date:
Sun, 14 Jul 2002 13:08:28 -0400
From:
Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (www.getipm.com)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State of California, Department of Pesticide
Regulation
cc: Christine Whitman whitman.christine@epa.gov
Environmental Health Perspectives Volume 106, Number 8, August 1998
[ Citation in PubMed ] [ Related Articles ]
Mode of Carcinogenic Action of Pesticides Inducing Thyroid Follicular Cell Tumors in Rodents
Pamela M. Hurley, Richard N. Hill, and Rick J. Whiting
Office of Prevention, Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington, DC 20460 USA
Abstract
Of 240 pesticides screened for carcinogenicity by the U.S. Environmental
Protection Agency Office of Pesticide Programs, at least 24 (10%) produce
thyroid follicular cell tumors in rodents. Thirteen of the thyroid
carcinogens also induce liver tumors, mainly in mice, and 9 chemicals produce
tumors at other sites. Some mutagenic data are available on all 24 pesticides
producing thyroid tumors. Mutagenicity does not seem to be a major
determinant in thyroid carcinogenicity, except for possibly acetochlor;
evidence is less convincing for ethylene thiourea and etridiazole. Studies on
thyroid-pituitary functioning, including indications of thyroid cell growth
and/or changes in thyroxine, triiodothyronine, or thyroid-stimulating hormone
levels, are available on 19 pesticides. No such antithyroid information is
available for etridiazole, N -octyl bicycloheptene dicarboximide,
terbutryn, triadimefon, and trifluralin. Of the studied chemicals, only
bromacil lacks antithyroid activity under study conditions. Intrathyroidal
and extrathyroidal sites of action are found: amitrole, ethylene thiourea,
and mancozeb are thyroid peroxidase inhibitors; and acetochlor, clofentezine,
fenbuconazole, fipronil, pendimethalin, pentachloronitrobenzene, prodiamine,
pyrimethanil, and thiazopyr seem to enhance the hepatic metabolism and
excretion of thyroid hormone. Thus, with 12 pesticides that mode of action
judgments can be made, 11 disrupt thyroid-pituitary homeostasis only; no
chemical is mutagenic only; and acetochlor may have both antithyroid and some
mutagenic activity. More information is needed to identify other potential
antithyroid modes of thyroid carcinogenic action. Key words :
induction of hepatic microsomal enzymes, iodide pump, mode of carcinogenic
action, 5´-monodeiodinase activity, pesticides, thyroid follicular cell
tumors, thyroid hormone, thyroid peroxidase activity, thyroid-stimulating
hormone. Environ Health Perspect 106:437-445 (1998). [Online 26 June
1998]
http://ehpnet1.niehs.nih.gov/docs/1998/106p437-445hurley/abstract.html
Address correspondence to P.M. Hurley, Office of Pesticide Programs (7509C),
U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, DC
20460 USA.
The authors would like to acknowledge the help of Esther Rinde in determining
the number of pesticide peer reviews and John Abbotts for drawing the
chemical structures.
Received 29 September 1997; accepted 16 April 1998.
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Last Update: June 26, 1998
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