Occurrence and fate of 1-chloro-2,2-bis(4-chlorophenyl)ethene in the environment of the Pearl River Delta, South China.

1-Chloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDMU), a metabolite of either 1,1-dichloro-22-bis(4-chlorophenyl)ethane (p,p'-DDD) or 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDE), which is degraded from 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-DDT), was detected in a variety of environmental matrices of the Pearl River Delta (PRD), South China, including fish, fish feeds, semidigested fish stomach contents, marine surface sediment, surface soil, atmospheric gaseous phase, and particulates, rainwater, and coastal rainwater. Forfish species,the concentrations of p,p'-DDMU were significantly higher in farmed fish than in marine wild fish, with the highest value obtained in seawater farmed fish species (mear/median values of 262/173 ng/g lipid). The relative abundance of p,p'-DDMU to total DDTs (sum of o,p'- and p,p'-DDT, DDD, and DDE) was higher in samples of marine origin (approximately 5%) than in those of terrestrial origin (approximately 2%). Because p,p'-DDD was considerably abundant in all samples and a negative linear correlation was found between p,p'-DDD/(p,p'-DDD + p,p'-DDE) and p,p'-DDMU/DDTs in the marine sediments (r2 = 0.73) and seawater farmed fish (r2 = 0.29) under investigation, it is possible that DDMU was partially dehydrochlorinated from DDD in the environment of the PRD. A fugacity-based assessment suggested that p,p'-DDMU is likely to transport from sediment to seawater and then to air and from soilto air. The ubiquity of p,p'-DDMU in the PRD indicates that it may also be widespread worldwide particularly in countries with large amounts of DDT used currently and/or historically. Given the potential risk of p,p'-DDMU to human health, more efforts should be directed toward to this previously overlooked contaminant