Factors affecting levels of DDT and metabolites in human breast milk from Kwazulu.

Concentrations of p,p'-DDT, p,p'-DDE, and p,p'-DDD have been determined in breast milk of mothers residing in two different areas of KwaZulu. Annual intradomiciliary application of DDT was used for the interruption of malaria transmission in one area, while the other served as the control. Milk from mothers living in DDT-treated dwellings had significantly higher mean levels of DDT and metabolites (mean sigma DDT 15.83 mg kg-1 in milk fat) than those from the control area (0.69 mg kg-1). The highest recorded sigma DDT value was 59.3 mg kg-1 (milk fat). Primiparous mothers from the malarious area had significantly more sigma DDT and metabolites (sigma DDT 24.82 mg kg-1) than multiparous mothers from the same area (mean 12.21 mg kg-1). Parity was the best predictor of DDT in breast milk of the exposed group. The percentage DDT and the sigma DDT increased significantly with an increase in parity. The same, but not significant, trend was also found for the control group. It was hypothesized that the increase in percentage DDT that occurred with higher parities was due to the uptake of DDT and elimination via milk. This process was faster than the uptake and endogenous formation of DDE. Designing predictive models using multiple regression was not very successful. The recorded levels do not represent an appreciable health risk to the mothers. From the literature it was deduced that at the recorded levels, a well-founded risk to the infants, particularly the firstborns, exists in sprayed areas.