Critical Assessment of 2-Methylpyridine: A Cause for Renewed Concern

Abstract

2-Methylpyridine (2Mp) is a refractory xenotoxin naturally found in coal/crude oil reserves and used anthropogenically as a solvent/intermediate in agrochemical, pharmaceutical, and textile industries on a large scale. It has been classified as a hazardous pollutant (USEPA and EU) and a High Production Volume chemical (USEPA). Limits were set initially (1991) to curb the manufacture of 2Mp within the US, which indeed had led to a decrease in its usage volume from 1991 to 2008. However, no such limit was found on the import of 2Mp into the US, which has led to a hundred-fold increase in 2Mp usage in the last decade. This implies that 2Mp was now being imported from developing countries apart from being produced locally. This trend is directly related to the increased interest in the treatment of 2Mp in the last decade and a half (2007–2023) in developing countries like India, China, Jordan, Russia, Iran, and South Korea. Further, there is no availability of monitoring data in developing countries. There is thus an immediate need to highlight 2Mp as a pollutant of “re-emerging” concern. This review discusses historic and current literature on 2Mp, so that policy makers and researchers alike may focus their attention and update the official hazard standards to incorporate the new threat posed by 2Mp. This review summarizes the synthesis, usage trend, hazardous categorizations, toxicity, effluent discharge standards, incidence case-studies, contact mechanisms, quantification, remediation, and recovery techniques used for 2Mp.