Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

32 lbs a.i./acre/year for alfalfa, broccoli, cabbage, corn, lettuce, onions, and spinach (EPA
2007).
Few crop scenarios were assessed relative to the number of approved uses. The BEs
provided pesticide exposure estimates from uses in relatively few crops considering the
number of registered uses of carbofuran, carbaryl, and methomyl. For example, estimates
of carbaryl exposure were provided for nine agricultural crops. An evaluation of
currently registered uses of a single carbaryl product label (Sevin brand XLR plus
carbaryl insecticide) revealed the product can be applied to more than 75 agricultural
crops in California alone (CDPR 2009). Similarly, the product Furadan 4-F Insecticide -
Nematicide (carbofuran) can be applied to more than 20 use sites in California while
exposure estimates evaluated only 5 agricultural crops. Finally, DuPont Lannate SP
Insecticides (methomyl) is authorized for use on more than 80 agricultural crops in
California while the BE provided exposure estimates for only 4 crops for all methomyl
products. NMFS also reviewed aquatic exposure estimates developed by EPA to assess
the risk of carbaryl and methomyl to the red legged frog (EPA 2007). Although these
estimates were specific to registered uses in California only, they represent a more
thorough evaluation of uses than was provided in the BEs. Estimates for agricultural
crops were relatively comparable to estimates in the BEs with most scenarios predicting
concentrations of carbaryl and methomyl within an order of magnitude (10-100 µg/L).
Exposure estimates associated with carbaryl use in rice (2,579 µg/L) were a notable
exception and this use was not evaluated in the BE. The acute EECs for carbaryl ranged
from 6 – 167 µg/L for other crops assessed versus 1-153 µg/L in the BE. Acute EECs for
methomyl ranged from 3 – 183 µg/L versus 30-99 µg/L in the BE.
Crop scenarios are likely not representative of the entire action area. The regional
scale that the modeled scenarios are intended to represent is unclear. Many of the
scenarios were conducted for states outside the distribution of listed salmonids. The
methomyl BE did not provide information on geographic locations simulated (e.g.,
county, state, region, etc.). The assumed rainfall and other site-specific input
assumptions can have large impacts on predicted exposure. For example, the carbofuran
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