Regulations often are imposing long postmortem times before autopsy leading to certain toxicity-unrelated changes in
biomarkers, which in turn may affect the reliability of toxicity evaluation during forensic investigations. Since
methomyl pesticide shows significant toxicity and is frequently encountered in
poisoning cases, the current study evaluated different parameters in
methomyl intoxicated rats at three different postmortem intervals (Hour 0, Hour 3 and Hour 6). Eighteen adult Sprague Dawley rats were poisoned with
methomyl to simulate actual
methomyl poisoning cases. The time of death was assigned as Hour 0. The animals were divided into 3 groups (n = 6) to collect blood and tissue samples at the selected time points.
Body weight, relative organ weight,
protein concentration,
methomyl concentration and
acetylcholinesterase activity (AChE) were assessed in blood and different tissues (liver, spleen, kidney, brain, eye, and bone marrow) to evaluate the effect of postmortem sampling time. Outcomes revealed significant decreases in
methomyl concentration in blood and bone marrow with advanced sampling time (P < 0.001). Similarly, there were significant reductions in AChE activity in the kidney (P < 0.01), while the
enzyme activity significantly increased in brain samples (P < 0.05). Findings illustrated the importance of sampling time in toxicity studies because it could alter experimental results and impact consequent interpretations, as well as it may alter postmortem
biomarkers in related forensic cases.