Monochlorostyrenes and octachlorostyrene: Toxicity, persistence, and safety considerations for potential contamination

Polychlorinated styrenes (PCSs) are a class of compounds with a styrene (vinyl benzene) structure in which chlorine atoms displace hydrogen atoms. The group contains 159 theoretically possible isomeric PCSs containing one to eight chlorine atoms. This review addresses the toxicity, formation, analytical methodologies, and occurrences of 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, and octachlorostyrene (OCS). These compounds have been primarily determined using gas chromatography coupled with mass spectrometry (GC/MS), achieving sub ng/g sensitivity, meanwhile, multistep cleanup procedures such as silica, Florisil, and gel permeation chromatography are commonly applied for high lipid matrices. Monitoring studies have frequently reported OCS at ng/g levels in lake sediments and fish, often co-occurring with heptachlorostyrene, hexachlorostyrene, and other persistent organochlorines, polychlorinated biphenyls (PCBs). These findings underscore their persistence of PCSs, industrial origins, and the need for improved analytical validation and continued environmental surveillance.