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

egarding acute toxicity of 1-napthol to aquatic invertebrates was provided in the Science
Chapter (EPA 2003).
Overall, results presented show that carbaryl and formulations of carbaryl are acutely toxic to a
wide array of aquatic invertebrates in the low μg/L range, frequently with EC50s/LC50s of less
than 10 μg/L. The degradate, 1-napthol, appears less toxic with respect to comparable
invertebrates; acute survival EC50s ranged from 200-730 μg/L. However, no data for the genera
more sensitive to the parent carbaryl, such as the stoneflies, caddisflies, or mayflies, are
available. Thus the lower end of the toxicity range is not well established.
The carbaryl BE (EPA 2003) lists a NOAEC of 1.5 μg/L and a LOAEC of 3.3 μg/L for D.
magna based on reproduction and a NOAEC of 500 μg/L and a LOAEC of 1,000 μg/L for the
midge fly (Chironomous riparius) based on emergence/developmental rate. Specific percentages
of inhibition are not noted. The Science Chapter (EPA 2003) does not add any additional detail,
but does note:
“midge larvae are benthic macroinvertebrates and exposure may
have been better characterized had it been based on sediment pore
water concentrations as opposed to carbaryl concentrations in
overlying water”
as a potential explanation for the difference in sensitivity between D. magna and C. riparius. No
data regarding reproductive endpoints were presented for 1-napthol.
The carbofuran BE (EPA 2004) included acute EC50s for the D. magna (29-38.6 μg/L) and pink
shrimp (Penaeus duorarum, 4.6-7.3 μg/L). All tests appear to have been conducted with the a.i.
EC50s of 2.2-2.6 μg/L were reported in the Science Chapter (EPA 2005) for the freshwater water
flea Ceriodaphnia dubia. The Science Chapter also provided toxicity values for the freshwater
red crayfish (Procambarus clarkii, LC50 2,700 μg/L) and the eastern oyster (Crassostrea
virginica, EC50s of >1,000->5,000 μg/L). Probit slopes were included in Appendix H of
Appendix 1 (EPA 2005) for studies where they were reported or data were available to calculate
them. Probit slopes were not available for D. magna or C. dubia, but were available for the red
crayfish (slope 2.91) and the pink shrimp (slope 2.25). Data provided from chronic toxicity tests
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