Biological monitoring of exposure to pirimicarb: hydroxypyrimidines in human urine

Pirimicarb (2-dimethylamino-5,6-dimerhylpyrimidin-4-yldimethylcarbamate) is used as insecticide in agriculture and fruit growing. During its metabolis m in mammals the carbamate moiety is hydrolysed and subsequent demethylatio n at the dimethylaminogroup which is attached to the heterocyclic moiety re sults in the following major metabolites which are excreted in urine: 2-dim ethylamino-5,6-dimethyl-4-hydroxypyrimidine (DDHP), 2-methylamino-5,6-dimet hyl-4-hydroxypyrimidine (MDHP), and 2-amino-5,6-dimethyl-4-hydronypyrimidin e (ADHP). These metabolites were detected in every urine sample of seven wo rkers who had applied pirimicarb. Concentrations of the MDHP and ADHP were much higher than that of DDHP indicating a considerable demethylation capac ity in humans. No metabolites were found in urine specimens of controls. Th e investigated pyrimidines represent sensitive and specific parameters for biological monitoring of exposure to pirimicarb. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.