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A method to determine precise benchmark doses for carbamate anticholinesterases
T Leon Lassiter1, Stephen Brimijoin
1Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota 55905, USA. lassiter.tommie@mayo.edu
Summary
A new assay accurately quantifies low levels of cholinesterase inhibition by carbamate pesticides. This method enables precise benchmark dose determination for risk assessment, even with few subjects.
Area of Science:
- Toxicology
- Biochemistry
- Environmental Health
Background:
- Accurate quantification of cholinesterase inhibition is crucial for regulating carbamate pesticides.
- Existing methods may require large sample sizes or lack precision at low inhibition levels.
Purpose of the Study:
- To develop a sensitive and accurate assay for measuring low-level cholinesterase inhibition by carbamates.
- To establish a method for determining benchmark doses (BMDs) for risk assessment.
Main Methods:
- Developed a carbamate-protection assay utilizing cholinesterase's resistance to irreversible inactivation.
- Enzyme activity is measured after protection and subsequent reactivation via decarbamylation.
- Size-exclusion centrifugation removes small molecules, and unprotected enzyme is silenced for low background.
Main Results:
- The assay detects statistically significant 2-3% cholinesterase inhibition in small sample groups.
- Applied to formetanate-treated rats, the assay predicted a BMD10 of 0.19 mg/kg (BMDL10 = 0.15 mg/kg).
Conclusions:
- The carbamate-protection assay offers precise determination of benchmark doses for carbamate pesticides.
- This method facilitates accurate assessment of low-dose in vivo inhibition and half-lives.
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