Occupational determinants of serum cholinesterase inhibition among organophosphate-exposed agricultural pesticide handlers in Washington State.
OBJECTIVE
To identify potential risk factors for serum cholinesterase (BuChE) inhibition among agricultural pesticide handlers exposed to organophosphate (OP) and N-methyl-carbamate (CB) insecticides.


METHODS
We conducted a longitudinal study among 154 agricultural pesticide handlers who participated in the Washington State cholinesterase monitoring program in 2006 and 2007. BuChE inhibition was analysed in relation to reported exposures before and after adjustment for potential confounders using linear regression. ORs estimating the risk of BuChE depression (>20% from baseline) were also calculated for selected exposures based on unconditional logistic regression analyses.


RESULTS
An overall decrease in mean BuChE activity was observed among study participants at the time of follow-up testing during the OP/CB spray season relative to pre-season baseline levels (mean decrease of 5.6%, p<0.001). Score for estimated cumulative exposure to OP/CB insecticides in the past 30 days was a significant predictor of BuChE inhibition (beta=-1.74, p<0.001). Several specific work practices and workplace conditions were associated with greater BuChE inhibition, including mixing/loading pesticides and cleaning spray equipment. Factors that were protective against BuChE inhibition included full-face respirator use, wearing chemical-resistant boots and storing personal protective equipment in a locker at work.


CONCLUSIONS
Despite existing regulations, agricultural pesticide handlers continue to be exposed to OP/CB insecticides at levels resulting in BuChE inhibition. These findings suggest that modifying certain work practices could potentially reduce BuChE inhibition. Replication from other studies will be valuable.
Hofmann
Jonathan N
JN
Department of Epidemiology, University of Washington, Seattle, Washington, USA. hofmannjn@mail.nih.gov
Keifer
Matthew C
MC
De Roos
Anneclaire J
AJ
Fenske
Richard A
RA
Furlong
Clement E
CE
van Belle
Gerald
G
Checkoway
Harvey
H
D000328:Adult; D000382:Agricultural Workers' Diseases / Q000097:blood* / Q000453:epidemiology; D000383:Agriculture; D000465:Algorithms; D002800:Cholinesterase Inhibitors / Q000097:blood* / Q000494:pharmacology; D006801:Humans; D007306:Insecticides / Q000633:toxicity*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000009:adverse effects*; D009943:Organophosphorus Compounds / Q000633:toxicity*; D018570:Risk Assessment; D012959:Socioeconomic Factors; D014861:Washington; D055815:Young Adult
D002800:Cholinesterase Inhibitors; D007306:Insecticides; D009943:Organophosphorus Compounds