Nonlethal method for forensic evaluation of aldicarb exposure in wildlife

Forensic evaluation of aldicarb exposure is difficult due to the rapid hydrolysis and oxidation of the parent compound. Oxidation products-aldicarb sulfoxide and aldicarb sulfone-are commonly analyzed, but hydrolytic products-aldicarb nitrile, aldicarb nitrile sulfoxide, aldicarb nitrile sulfone-are infrequently analyzed even though they are the primary stable products of aldicarb degradation. Nitrile analyses provide an important avenue to verify aldicarb exposure or aldicarb-induced mortality. Our aproach allows lethal and sublethal exposure assessment. Extraction of samples with acetonitrile:water is followed by chromatographic determination. Sublethal exposure assessment utilizes excreta samples, which is nonlethal and requires holding animals in captivity for 12 h or less. Sublethal exposures of northern bobwhite Colinus virginianus to aldicarb can be identified with greater than 80% confidence for 6 h after dosing. By analyzing GI tracts, lethal exposures of bobwhite to aldicarb can be identified with greater than 90% confidence for 4 days post mortem and with 75% confidence for 8 days post mortem. Sublethal exposures to aldicarb was identified in greater than 80% of Peromyscus maniculatis for 6 h after dosing. Aldicarb and its transformation products were detected for 8 days post mortem in all mice that received aldicarb doses at or above the LD50.