Polychlorinated Biphenyl

Abstract

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants, found in the many environments. PCBs exerts various toxicological effects, including endocrine-disrupting activity. Most researches with these toxicants performed with soil matrix with mixtures of congeners, namely Aroclor, while the biological activities have been tested with animals. However, studies with pure congeners are limited. In this study, 5 congeners were synthesized and their fates (bioaccumulation, degradation, kinetics) were studied in carrot-soil system. The soil half-lives of biphenyl, PCB-1, PCB-3, PCB-77, and PCB-126 were 20.2, 16.0, 11.6, 46.5, 198.0 days, respectively. In general, the longer half-lives were observed with the higher hydrophoicity of PCBs. Times, required for maxium accumulation of PCBs in carrot (Tmax) were 10-20 days for most congeners and the concentrations were 0.4-2.6 mg/kg. The concentrations of PCBs in carrot were kept as constant after Tmax, except PCB-126. The concentration ratio between carrot and soil after 90 days of treatment were 1.7, 8.1, 1.9, 1.8, and 5.9 for biphenyl, PCB-1, PCB-3, PCB-77, and PCB-126. Because of the increase of biomass, the total residual amount of PCBs in carrots however, increased till the end of experiment. The portions of PCB-126 in carrot were 1.1% of the soil residues at 90 days after planting.