US EPA

2192682 

Journal Article 

Abstract 

2,2',4,4',5,5'-Hexachlorobiphenyl as an antagonist of the teratogenicity of 3,3',4,4',5-pentachlorobiphenyl in C57BL/6 mice 

Zhao, F; Mayura, K; Safe, S; Phillips, TD 

1995 

1 

Toxicologist
ISSN: 0731-9193 

15 

1 

English 

Polychlorinated biphenyls (PCBs) are widespread environmental contaminants. Among the PCBs, 3,3',4,4',5-pentachlorobiphenyl (PeCB) is the most toxic coplanar PCB congener. Recent studies have demonstrated the teratogenicity of PeCB in mice. This study was designed to investigate the potential of 2,2',4,4',5,5'-hexachlorobiphenyl (HeCB) as an antagonist of the teratogenicity of PeCB in C57BL/6 mice. Pregnant mice were administered orally a single dose of PeCB (dissolved in corn oil) at concentrations ranging from 522 to 2088 ug/kg body weight, either alone or in combination with a dose of HeCB (271 mg/kg) on day 10 of gestation. Fetuses were examined on day 17 for the presence of cleft palate and hydronephrosis. The results indicated a concentration-dependent increase in the incidences of cleft palate (ranging from 21 to 100%) in PeCB treatment groups. HeCB alone did not induce cleft palate. Cotreatment of dams with PeCB plus HeCB significantly reduced the number of fetuses with cleft palate in all treatment groups, except the group treated with the highest dose of PeCB (i.e., 2088 ug/kg). PeCB (1044, 783 or 522 ug/kg) produced 64, 45 and 21% of fetuses with cleft palate, respectively; whereas, the same doses of PeCB plus HeCB resulted in only 13, 4 and 0% of fetal cleft palate. Interestingly, HeCB did not antagonize PeCB-induced hydronephrosis in any of the treatment groups. The results from this study demonstrate that HeCB is a partial antagonist of PeCB-induced teratogenicity in C57BL/6 mice.