The Metabolic Fate of [Vinyl-I-¹⁴C]Dichlorvos in the Rat after Oral and Inhalation Exposure

Abstract

1. [Vinyl-1-¹⁴C]Dichlorvos is rapidly metabolized when administered orally to the rat, the major metabolite being [¹⁴C]carbon dioxide.

2. Much of the administered radioactivity is incorporated into the pathways of intermediary metabolism and thus the residual radioactivity associated with the carcass four days after the treatment is relatively high. Most of the radioactivity retained in the livers of treated animals has been identified as [¹⁴C] glycine and [¹⁴C]serine, incorporated into liver protein. It is probable that the amino acids were synthesized via dichlorvos, dichloroacetaldehyde and glyoxylate.

3. At least nine radioactive metabolites were found in urine; those identified were hippuric acid (8.3% of urinary radioactivity); desmethyldichlorvos (10.9%), dichloroethanol glucuronide (27%) and urea (3.1%).

4. The rapid detoxification of dichlorvos can be attributed to hydrolytic and demethylation reactions, leading to dichloroacetaldehyde, which is then partly reduced to dichloroethanol and excreted as the glucuronide and also partly dechlorinated and incorporated into a two-carbon biosynthetic pathway.

5. When [¹⁴C]dichlorvos was inhaled by rats, the excretion and retention data, together with analysis of radioactive metabolites in the liver, and in urine, indicated that the gross pathways of metabolism did not appreciably differ from those observed after oral administration.