Organochlorine residues in maternal milk from inhabitants of the Thohoyandou area, South Africa

Abstract

The presence of organochlorine compounds (OC) such as DDT and their metabolites in the environment have created a significant environmental concern over the years due to adverse effects. Consequently, DDT has been banned in many countries. However, it is still used in some countries including South Africa, particularly for vector-borne disease eradication programmes. Since the presence of DDT and its metabolites may provide an indication of the general exposure and use of these compounds, there was a need for such a study. Human breast milk samples (n = 30) were collected from mothers within the age range of 19–40 years from the Thohoyandou area, South Africa. The liquid–liquid extraction method was used to extract DDT and its metabolites from the samples. The crude extracts were subjected to column chromatography for measurements of OC levels. The concentration ranges of the contaminants were as follows: not detected (ND) to1770 ng g⁻¹ (2,4′-DDE); ND to 3977 ng g⁻¹ (4,4′-DDE); ND to 3250 ng g⁻¹ (2,4′-DDD); ND to 2580 ng g⁻¹ (4,4′-DDD) and ND to 2847 ng g⁻¹ (4,4′-DDT). The mean ΣDDE, ΣDDD and ΣDDT obtained from the villages were 1180 ng g⁻¹, 830 ng g⁻¹ and 690 ng g⁻¹, respectively. The total DDT ranged from 820–7473 ng g⁻¹. The estimated daily intake varied from 260 to 4696 ng g⁻¹, ND-10551 ng g⁻¹ and ND-4237 ng g⁻¹ for DDE, DDD and DDT, respectively. These values are significantly higher than the FAO/WHO acceptable daily intake (ADI) of 20 ng g⁻¹. The ΣDDT was found to decrease with increasing age of the mothers. The observed high levels of DDE compared to DDT indicated chronic exposure of the mothers to DDT, which is metabolized to DDE and retained in the body.

Keywords:

• DDT
• metabolites
• human
• breast milk
• Thohoyandou
• South Africa

Acknowledgements

The authors are grateful to the National Research Foundation of South Africa and Tshwane University of Technology, Pretoria, South Africa for financing Mr T.N. Mutshatshi to conduct this research for an MTech degree in Environmental Management. The mothers who donated their precious food, breast milk, and the nurses who participated in this project are gratefully acknowledged.