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

24 hr exposure (Zinkl, Shea et al. 1987). In another study with cutthroat trout within 42 h
recovery occurred following 6 h exposure(Labenia, Baldwin et al. 2007). In the latter study,
cutthroat trout recovered approximately half of their pre-exposure AChE activity within 6 h,
following peak AChE inhibition within 2 h. Both of these studies indicate that recovery of
AChE activity following exposure to carbamates occurs quickly and is highly dependent on
environmental exposure conditions found in aquatic habitats.
We did not locate additional studies with other carbamates, but located multiple studies with OP
insecticides. The OPs chlorpyrifos, diazinon, and malathion showed significant and persistent
effects to a suite of swimming related behaviors in salmonids at concentrations expected in
salmonid habitats; as reviewed in NMFS’ November 18, 2008 Opinion on these three OP
insecticides (NMFS 2008). Robust evidence of the three OPs showed reductions in swimming
speed (Brewer, Little et al. 2001), distance swam (Brewer, Little et al. 2001), acceleration
(Tierney, Casselman et al. 2007), food strikes (Sandahl, Baldwin et al. 2005) and significant
correlations with AChE activity (Brewer, Little et al. 2001; Sandahl, Baldwin et al. 2005).
Additionally, other OPs including fenitrothion, parathion, and methyl parathion, adversely
affected a suite of swimming behaviors reviewed by (Little and Finger 1990). One noteworthy
study investigated the effects of six pesticides including methyl parathion (OP) and tribufos (OP)
on rainbow trout swimming behavior (Little, Archeski et al. 1990). All insecticides adversely
affected spontaneous swimming activity, while DEF also reduced swimming capacity in juvenile
rainbow trout (Little, Archeski et al. 1990). In bluegill, methyl parathion adversely affected
burst swimming behavior at 300 μg/L (Henry and Atchison 1984). Respiratory disruptions,
comfort movements, and aggression behaviors in bluegill were all adversely affected by 24 h
exposures to methyl parathion at 3.5 μg/L. This suggests that these social behaviors are very
sensitive to AChE inhibition (Henry and Atchison 1984).
Two month old juvenile rainbow trout, brook trout, and coho were exposed to malathion
(Phillaps Malathion 55%) for 7-10 days depending on species (Post and Leasure 1974).
Swimming performance, brain AChE activity, and recovery time were measured following
exposure to malathion concentrations of 0, 40, 90, 120 μg/L in brook trout; 0, 55, 112, 175 μg/L
in rainbow trout; and 0, 100, 200, 300 μg/L in coho. Additionally, once fish recovered AChE
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