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 metabolism in mammals the carbamate moiety is hydrolysed and subsequent demethylation at the dimethylaminogroup which is attached to the heterocyclic moiety results in the following major metabolites which are excreted in urine: 2-dimethylamino-5,6-dimethyl-4-hydroxypyrimidine (DDHP), 2-methylamino-5,6-dimethyl-4-hydroxypyrimidine (MDHP), and 2-amino-5,6-dimethyl-4-hydronypyrimidine (ADHP). These metabolites were detected in every urine sample of seven workers who had applied pirimicarb. Concentrations of the MDHP and ADHP were much higher than that of DDHP indicating a considerable demethylation capacity in humans. No metabolites were found in urine specimens of controls. The investigated pyrimidines represent sensitive and specific parameters for biological monitoring of exposure to pirimicarb. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.