Diagnostic Aspects of Paraquat in the Forensic Toxicology: A Systematic Review

Paraquat (N, N-dimethyl-4,4-bipyridinium dichloride) is a nonselective, fast-acting, and contact chemical herbicide used extensively for weed control. It has high acute oral toxicity, the ability to accumulate in the lungs, and a high potential for pulmonary fibrosis after its intoxication. The present systematic review focuses on evaluating diagnostic aspects of paraquat (PQ) in forensic toxicology.

Evaluation of the literature according to the following criteria: only human studies published from February 1971 to March 2022 which are in English on the following databases: 1) Medline/PubMed/MeSH search words: ((Methyl viologen [Title/Abstract]) OR (paraquat [MeSH Terms])) AND (forensic [Title/Abstract]); 2) Scopus Keywords related to the study aim included forensic toxicology, paraquat, Methyl viologen; 3) Web of Science. Keywords related to the study aim included forensic toxicology, paraquat, and Methyl viologen.

Thirty full-text articles were included. The results of our review indicate plasma and urine are more used for identifying PQ, and liver, lung, and gastric fluid are important in postmortem cases. Preparation methods, including liquid-liquid extraction (LLE), solid-phase extraction, and acetonitrile-precipitated protein, are often required for removing interfering substances. Chromatographic methods, among other analytical techniques, are more sensitive, specific, and applicable.

Our review suggests that plasma, urine, and lungs should be prioritized in sampling. Solid-phase extraction has better recovery than LLE in many samples. Colorimetric methods are not used much today, and radioimmunoassay (RIA) has limited application despite its high sensitivity. Gas and liquid chromatography methods appear to offer the best approach for the analysis of PQ.