Exposure to PCBs and p,p′-DDE and human sperm chromatin integrity

Abstract

Persistent organochlorine pollutants (POPs) such as polychlorinated biphenyl PCBs) and dichlorodiphenyldichloroehtylene (p,p′-DDE), the major metabolite of dichlorodiphenyl-trichloethane (DDT), are stable lipophilic compounds widely found in the environment and in the general population. They can enter the food chain, and their negative impact on male reproduction is currently active scrutiny. To explore the hypothesis that environmental exposure to these compounds is associated with altered sperm chromatin structure intergrity in human sperm, we conducted a study of 176 Swedish fishermen (with low and high consumption of fatty fish, a very important exposure source of POPs). We determined serum levels of 2,2′,4,4′,5,5′ hexachlorobiphenyl (CB-153) p,p′-DDE, and we used the sperm chromatin structure assay (SCSA) to assess sperm DNA/chromatin integrity. When CB-153 serum levels (individual dose range, 39-1,460 ng/g lipid) were categorized into equally sized quintiles, we found an association with the DNA fragmentation index (%DFI). A significantly lower %DFI was found in the lowest CB-153 quintile (< 113 ng/g lipid) compared with the other quantiles; there was a similar tendency, although not statistically significant, between %DFI and p,p′-DDE. These results suggest that POP exposure may have a slight negative impact on human sperm chromatin integrity.