investigation of concentration and pattern of polychlorinated biphenyls (pcbs) distribution in five edible fish species from shadegan wetland

organochlorine contaminants are highly stable and dangerous compounds, which are widespread in the environment. among these compounds, polychlorinated biphenyls (pcbs) are carcinogenic for humans and can also affect intellectual functions and the nervous, immune and reproductive systems. aquatic organism especially fishes are known to be main routes for e entrance of these compounds to the humans bodies. this research investigated accumulation and distribution pattern of pcbs in 5 edible fish species gathered   from shadegan wetland and effects of various factors on concentration of these contaminants. determination of concentration of these pollutants in specimens is performed using gas chromatography. results showed that among pcbs, concentration of pcb-52 was the highest in barbus barbulus, barbus sharpeyi and cyprino carpio 2.03, 4.64 and 1.92 ng/g wet wt, respectively. in barbus grypus pcb-28, had the highest concentration (4.68 ng/g wet wt) and pcb-138 had the predominant pollutant in aspius vorax (4.10 ng/g wet wt).  mean concentration of pcbs in barbus barbulus was the highest (kruskal-wallis- mann-whitney u), which can be related to carnivorous diet of this species.  investigation showed that mean concentration of pcbs was higher in weight group of 0-320 g and in age group of over 3 years and carnivorous diet (mann-whitney u(.