Faculty of Health Sciences
School of Health Systems and Public Health
School of Health Systems and Public Health
Selected Highlights from Research Findings
In response to mounting concerns about the influence of environmental chemicals on human health a cross-sectional epidemiological study was initiated by Prof Tiaan de Jager to specifically investigate the effects of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) (DDT) on male reproductive health. One hundred and seventy men from Venda in the Limpopo province, where DDT is still sprayed, participated in the project. Semen analyses, toxicological target analyses, and hormone profiles were included. Various sperm parameters were affected and very high concentrations of DDT and metabolites were detected in the blood serum. The effects of DDT on seminal parameters may not be ignored and the project will be extended. In addition to the epidemiological approach, reproductive toxicology studies were performed. A general trend in decreased fertility parameters was observed after exposure of rats to a mixture of DDT, deltamethrin, nonylphenol and phytoestrogens. DDT and deltamethrin at environmentally relevant concentrations had negative effects on reproductive health, with phytoestrogens in combination with other EDCs showing synergistic effects.
Prof Bornman focuses on urogenital birth defects in newborns and the transfer of chemicals to the unborn baby during pregnancy. In collaboration with Prof Una MacIntyre from the University of Limpopo, the nutritional status and dietary intakes of men, women and children were first addressed. The nutritional value of the diets was described and the food intakes identified, which could contribute as exposure route.
These are the first studies in the world to be conducted in currently DDT-sprayed high-risk malaria areas. Although DDT has been banned for international use, countries like South Africa have restricted use for malaria vector control. South Africa is a signatory to the Stockholm Convention on the control of Persistent Organic Pollutants (POP's) including DDT, and now has the obligation to limit and control the release of substances like DDT into the environment. The studies provide invaluable data on human health effects of people currently exposed to DDT and will support the Department of Environmental Health and Tourism and National Government in assessing health risk. The findings have already lead to a pilot intervention project by the Agricultural Research Council to improve dietary quality in Resource Poor Farmers and again confirm the need for safer alternatives for malaria control.
Contact person: Prof C de Jager.
Occupational health records of 37 206 South African miners employed between 2000 and 2003 at several mines all over the country were analyzed. The objective was to describe basic demographic and health-related characteristics of mine workers included in the South African Mines Occupational Diseases Database (SAMODD) and to estimate prevalence proportions, odds ratios and hazard ratios of occupational diseases commonly experienced by mineworkers for the years 2000 to 2003. It was found that, over the 4-year period, 64 of the 37 206 miners died. Cardio-respiratory tuberculosis (CRTB) was the most prevalent occupational disease, followed by noise-induced hear-loss, pneumoconiosis, silicosis, chronic obstructive airways disease and heat related diseases. Incidence rate ratios of CRTB were significant in gold mines in 2000, in platinum and asbestos mines in 2001, in platinum mines in 2002 and in all mines in 2003.
Contact person: Dr Z Worku.
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