In vitro reproductive toxicity of polychlorinated biphenyl congeners 153 and 126.

This study was conducted to investigate the applicability of an in vitro technique for maturation, fertilization, cleavage, and growth to blastocysts of bovine oocytes to investigate reproductive toxicologic effects. During maturation, the oocytes were exposed to the di-ortho-substituted PCB congener 2,2',4,4',5,5'-CB (PCB 153) in the three concentrations 0.84 ng/mL, 8.4 ng/mL, and 84 ng/mL or to the non-ortho-substituted PCB congener 3,3'4,4',5-CB (PCB 126) in the three concentrations 1.006 pg/mL, 10.06 pg/mL, and 100.6 pg/mL and compared with control groups. PCB 153 had no effect on maturation but resulted in a reduced proportion of oocytes that cleaved at the highest concentration. There were no differences in blastocyst development among groups. PCB 126 resulted in a reduction in maturation percentage at the highest concentration and in blastocyst development at all concentrations. These results demonstrated adverse effects of PCB congeners on bovine oocytes and showed that this system can be used to evaluate toxic effects on oocytes and preimplantation-stage embryos.

Time- and dose-dependent biom arker responses in flounder (Platichthys flesus L.) exposed to benzo[a]pyrene, 2,3,3',4,4', 5-hexachlorobiphenyl (PCB-156) and cadmium.

Responses in flounder (Platichthys flesus) towards benzo [a]pyrene (BaP), 2,3,3',4,4',5-hexachlorobiphenyl (PCB-156), and cadmium (Cd) were investigated in time-course and dose-response studies of selected biomarkers. Measurements of biliary fluorescent BaP metabolites and hepatic concentrations of PCB-156 and cadmium showed that the injected toxicants were rapidly m obilized from the muscle to the liver, but a depot effect was indicated in the highest dose groups of BaP and PCB-156 (12 mg kg(-1) bodyweight). Clearest biomarker responses were found in the induction of hepatic cytochrome P450 1A (CYP1A) enzymes as a response towards BaP and PCB-156 exposure. Maximum induction of CYP1A dependent 7-ethoxyresorufin O-deethylase (EROD) activity was observed after 2 and 8 days in BaP and PCB-156-treated flounder, respectively. Positive dose-effect relationships were observed towards both compounds, but the CYP1A induction was more persistent with PCB exposure than with BaP exposure. In Cd-exposed fish, the hepatic level of metallothionein responded more slowly with highest levels observed after 16 days in the time-study. In the combined BaP + Cd treatment, the CYP1A induction was only slightly suppressed. Aspartate aminotransferase in serum appeared to be responsive towards BaP, but also towards the acetone vehicle in controls in the first part of the exposure period. Hematocrit as well as hepatic activities of aldrin epoxidase, glutathione S-transferase, and UDP-glucuronyl transferase were not responsive to any treatm ent in the present study. In general, the results demonstrate that selected biom arkers in flounder are responsive to PAH, PCB, and heavy metal pollutant exposure, indicating the applicability of this species in future environmental pollution monitoring programmes.

Residues of organochlorine pesticides in human milk from mothers living in the greater Harare area of Zimbabwe.

Residue levels of the chlorinated hydrocarbons p,p -DDT, p,p, -DDE, p,p TDE, p,p -DDT, alpha-beta-gamma-hexachlorocyclohexane (HCH), heptachlor epoxide, dieldrin and polychlorinated biphenyls (PCBs) were determined in human milk of 40 Zimbabwean mothers living in the greater Harare area. Three municipal clinics and one main hospital were randomly selected as collecting points. The main organochlorine contaminants found in all the samples analysed were p,p -DDT and p,p -DDE and the mean levels of sum DDT and DDT/DDE ratio were 6 mg/kg milk fat and 0.74 respectively. In general, relatively low residue levels of alpha-beta-,gamma-HCH, heptachlorepoxide and dieldrin were detected in 58,100,63,13 and 65pc, respectively of all the milk samples analysed. Trace of the PCB congener 2,2,4,5,5'-pentachlorobiphenyl (PCB 101) were found in 15 samples and only one sample contained traces of 2,3',4,4',5-pentachlorobiphenyl (PCB 118). The results were examined with regard to health ad living condition of the mothers. From the small population observed around the greater Harare area--social status, educational background an living conditions could be described as important demographic variables influencing the frequency distribution of residual levels of sum DDT in the mother's milk.

PIP: Researchers analyzed data from interviews with 40 mothers living in suburban Harare, Zimbabwe and analyses of their breast milk to study contamination levels of organochlorine pesticides in breast milk. The 14 mothers living in the low-density suburbs of Milton Park, Queensdale, Avondale, and Borrowdale had a higher socioeconomic status and a higher educational status than the other mothers. These 14 mothers also had a nutritious diet and adequate knowledge of pesticides and their use (group 1). The high-density suburbs included Mbare, Mufakose-Kambuzuma, Dzivaresekwa, and Epworth. The 26 mothers living in these areas tended to be of a low socioeconomic status and have only primary education, poor diet, and limited pesticide knowledge (group 2). Breast milk of Group 2 mothers contained a higher mean level of total DDT (as expressed in ppm mg/kg of fat weight) and DDT/DDE ratio than group 1 breast milk, but the differences were insignificant (7.39 vs. 3.44 and 0.93 vs 0.37). The total DDT intake surpassed the acceptable daily intake (ADI) for infants based on the FAO/WHO ADI for adults. Yet no evidence existed that this amount was harmful to infants. The only metabolite found in the breast milk of all mothers was p,p'-DDE (the major metabolite of p,p'-DDT). Its mean was highest in group 2 breast milk (2.72 vs. 2.18). These results reflected the continued use of DDT in agriculture and effects of the malaria control program in Zimbabwe. The persistent levels of p,p'-DDE also indicated that the women ate meat from animals in which p,p'-DDE had accumulated. Residues of 3 lindane isomers were present in 58-100% of the breast milk samples with beta-HCH being the most persistent. Dieldrin and heptachlor epoxide levels were quite low (mean 0.05 and 0.01 respectively) indicating minimal use Zimbabwe. The researchers reiterated a commitment to breast feeding, but further research about the effects of pesticide residues is needed.

Organochlorine pesticides in human milk from different areas of Kenya 1983-1985.

Residue levels of the chlorinated hydrocarbons p,p'-DDT (2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane), p,p'-DDE (2,2-bis(p-chlorophenyl)-1,1-dichloroethane), hexachlorobenzene (HCB), alpha-, beta-, and gamma-hexachlorocyclohexane (HCH), aldrin, dieldrin, and polychlorinated biphenyls (PCBs) were determined in human milk of Kenyan mothers living in different areas of Kenya. The main organochlorine contaminants found in all the milk samples analyzed were p,p'-DDT and p,p'-DDE. Great regional differences were found, and mean levels of sum DDT and DDT/DDE ratio ranged from 1.1 to 18.7 mg/kg milk fat and from 0.7 to 5.7, respectively. In general, relatively low residue levels of HCB, alpha-HCH, beta-HCH, aldrin, and dieldrin were detected in 59, 37, 27, 37, and 19%, respectively, of all the milk samples analyzed. Quantifiable residue levels of PCBs and alpha-HCH were not found. The results were examined in relation to differences in living conditions with regard to agricultural activities, dietary habits, and reported use of pesticides in the various sampling areas.