Association of azinphos-methyl with rat erythrocytes and hemoglobin

To investigate whether hemoglobin might serve as a biomarker of exposure to azinphos-methyl (AZM) encountered by agricultural workers, we exposed rats to [C-14]azinphos-methyl ([C-14]AZM). We administered single doses of 1.5 mg/kg, 3 mg/kg, or 6 mg/kg of [C-14]AZM by gavage to rats and collected blo od 3 days later. We found a dose-dependent association between radioactivit y and erythrocytes and hemoglobin (measured by liquid scintillation spectro metry). In another experiment, we administered a single dose of 3 mg/kg [C- 14]AZM by gavage to rats and collected blood 3, 11, 15. and 22 days after a dministration. Radioactivity continued to be associated with erythrocytes a nd hemoglobin at all time-points. Brain and plasma acetylcholinesterase (AC hE) activities were not significantly inhibited, nor did we observe signs o f acute toxicity in any of the treated animals. Loss of radioactivity assoc iated with erythrocytes and hemoglobin over the study period was consistent with the expected kinetics of erythrocyte turnover, indicating adduct stab ility. Approximately 0.49%, 0.43%, 0.39%, and 0.32% of the original radioac tivity was recovered in the hemoglobin 3, 11, 15, and 22 days, respectively , after administration. These data support our hypothesis that AZM may form a hemoglobin adduct and may be useful as a biomarker of AZM exposure.