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MCPA C iptox,Dow MCP)Herbicide Profile 9/89 Page 4 of 6
<br /> dimethylamine salt and it ,tyl ester as their use patterns a �r for
<br /> significant potential expimmoare to bees. r/
<br /> Product Chemistry. The Agency is requiring that all product chemistry
<br /> data be resubmitted. Further, MCPA may be contaminated with dioxins
<br /> or dibenzofurans, and the amine salts of MCPA may be contaminated with
<br /> n-nitrosamines. Therefore, analytical data are required for certain
<br /> products.
<br /> Tolerance Assessment
<br /> Tolerances for residues of MCPA per se in or on food and feed
<br /> commodities are published in 40 CFR 180.339(a) . Tolerances for residues
<br /> of MCPA and its metabolite 2-methyl-chlorophenoxyacetic acid in or on
<br /> animal commodities are published in-40 CFR 180.339(b) .
<br /> The residue data reviewed in support of these tolerances showed the
<br /> ,,. following:
<br /> - Data on metabolism of MCPA in plants available for review in the 1982
<br /> document indicated that MCPA is readily taken up and translocated by
<br /> plants. Additional data are required on the identity and quantities
<br /> .� of residue in or on plants. The nature of the residue is not
<br /> adequately understood.
<br /> - Data pertaining to the residues of MCPA in animals were reviewed for
<br /> the 1982 document. That document did not require additional data on
<br /> animal metabolism. Current Guidelines specify that terminal residues
<br /> in animals be identified and quantified using radioactive material.
<br /> The metabolism of MCPA in animals is not adequately understood and
<br /> additional data are required.
<br /> - The current residue analytical methods in PAM I are adequate for
<br /> enforcement of tolerances for residues in plants and animals.
<br /> - Data depicting the stability of MCPA residues in storage were not
<br /> required in the 1982 document. Current Guidelines specify that
<br /> storage stability data must be submitted in support of established
<br /> tolerances.
<br /> - There are available data to support the established tolerances for
<br /> MCPA in or on canary grass seed and straw.
<br /> - Additional residue data are required on dried beans, peas (succulent
<br /> and dry) , pea vines and hay, rice grain, sorghum grains, wheat grains,
<br /> rice straw, sorghum forage and fodder, wheat straw, annual canary-
<br /> grass, pasture and rangeland grasses, grass hay, alfalfa and alfalfa
<br /> hay, flaxseed, and flax straw.
<br /> - The data requested on wheat grain, forage, and straw may, by
<br /> translation, support the established tolerances for residues of MCPA
<br /> in or on the grain, forage, and straw of barley, oats, and rye. The
<br /> data requested on alfalfa and alfalfa hay may, by translation, support
<br /> the established tolerances for residues of MCPA in or on clover and
<br /> clover hay, lespedeza and lespedeza hay, trefoil and trefoil hay, and
<br /> vetch and vetch hay.
<br /> - Arnraaaincs r9a to ara nccAcri nn rind nr�in r,�h ..n .. ..,L,00f ,-,
<br /> .. and flaxseed. The requirements for-processing data ronnbarley, oat,^
<br /> and rye grain may be satisfied by the data requested on wheat.
<br /> Tolerances need to be proposed for residues of MCPA in or on bean
<br /> vines and hay, barley hay, oat hay, rye hay, wheat forage and hay, and
<br /> canarygrass forage.
<br /> - Upon receipt of the data requested on animal metabolism and livestock
<br /> feed items, the established tolerances for the combined residues of
<br /> MCPA and 2-methyl-4-chlorophenol in the meat, fat, and meat by-
<br /> products of cattle, goats, hogs, horses, and sheep and in milk will be
<br /> assessed and the need for tolerances for residues in poultry tissues
<br /> and eggs will be determined.
<br /> - A provisional acceptable daily intake (PARI, RfD) of 0.0015 mg/kg/day
<br /> for MCPA has been established based on a 1- year feeding study (dog,
<br /> NOEL 0.15 mg/kg) . The value given is a PADI because of the teratology
<br /> data gaps. However, when the teratology studies are submitted and
<br /> found acceptable, they are not expected to greatly alter the RfD
<br /> calculations. A safety factor of 100 was utilized. The dietary
<br /> exposure was calculated using the published tolerances in 40 CFR
<br /> 180.339. A dietary exposure for the U.S. population is calculated to
<br /> be 0.001547 mg/kg/day, corresponding to 103 percent of the RfD. The
<br /> population subgroups with the highest calculated exposure were
<br /> ... nonnursing infants (0.007405 mg/kg/day, 493% of the RfD) and children
<br /> 1 to 6 years of age (0.004069 mg/kg/day, 271% of the RfD) . A dietary
<br /> http://pmep.cce.comell.edu/profiles/herb-growthreg/fatty-alcohol-monuron/mcpa/herb-prof-mcpa.html 10/30/2003
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