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

after flooding (Nicosia, Carr et al. 1991) as cited in (EPA 2004)). Concentrations declined to ≤5
μg/L by 37 d after flooding. The discussion does not describe when or how the carbofuran was
applied prior to flooding. Other studies described merely note that carbofuran does move into
surface water, and that concentrations decline over time. Ground water monitoring data for
carbofuran reported in the BE included concentrations of up 4.3 μg/L in wells on Long Island,
NY 20 years after use was prohibited, and a maximum reported concentration of 176 μg/L in
Suffolk County, NY.
The methomyl BE reports data from monitoring studies for specific crops that appear to have
been designed to approximate PRZM-EXAMS scenarios. These studies evaluated application
rates ranging from 0.3 – 1.35 lb ai/acre on crops such as cantaloupe, sweet corn, apples, lettuce,
and tomatoes. All of the studies included multiple applications (from 5 to 29) and short reapplication
intervals (1-5 d). Some studies measured concentrations in field runoff (96-1,320
μg/L), and all measured concentrations in various receiving waterbodies (4.6 – 175 μg/L).
Carbaryl is one of the pesticides used by the U.S. Department of Agriculture’s Animal and Plant
Health Inspection Service (APHIS) to control grasshopper infestations. Research was conducted
to evaluate the effects of rangeland aerial applications of a carbaryl formulation known as Sevin-
4-Oil (Beyers, Farmer et al. 1995). Fixed-wing aircraft were used to apply the carbaryl to
rangeland on both sides of the Little Missouri River. Pesticide applicators were instructed to
observe a 152 m no-spray buffer around the Little Missouri River. Carbaryl was applied at a rate
of 0.5 lbs a.i./acre in 1991 and 0.4 lbs per acre in 1993. Surface water concentrations were
monitored during a drought and non-drought year. During the study, discharge in the river
ranged from 0.026 to 0.057 m 3 /s in 1991 and 37.7 to 49.8 m 3 /s in 1993. Concentrations of
carbaryl in the river were monitored for 3 d following application (Table 59). Maximum values
in surface water were measured on the day of application and peaked at 85.1 and 12.6 μg/L in
1991 and 1993. Concentrations declined but were detectable when the study was terminated 96
h post treatment. Peak values were approximately 7 fold during the drought year when flows
were low, demonstrating the influence of dilution capacity on receiving water concentrations.
These values represent concentrations that might be observed in similar habitats used by listed
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