Faculty of Health Sciences
School of Health Systems and Public Health
School of Health Systems and Public Health
Selected Highlights from Research Findings
Many man-made chemicals occurring in the environment are known to interact with the development and functioning of endocrine systems in wildlife and humans. These chemicals are known as endocrine disrupting chemicals (EDCs) with potentially devastating health effects. The concern over persistent bio-accumulative EDCs, their probable bio-magnification and their synergistic effects has become a focus of research with distinct national challenges. Several health effects in humans, including sperm quality, hypospadias, cryptochidism, testicular and prostate cancer, breast cancer, neurological and immunological effects, are linked to EDC exposure. In South Africa EDCs do not only pose a health risk to the environment and wildlife, but also to humans, as South Africa is one of only a few countries still using the organochlorine pesticide, DDT, for malaria vector control. The limited water resources of South Africa, the rich biodiversity, the limited health budget, the likelihood of a significant contribution to pollution by industry, the lack of waste control, the use of EDCs in households and agriculture together with the need to use DDT for malaria vector control emphasizes the need for timely measures to be taken. Studies by the University’s School of Health Systems and Public Health (SHSPH) indicated EDC contamination of South African waters and health effects in different animal species (sentinel and laboratory). The schools’ research focuses on health effects associated with DDT exposure as well as exposure to environmentally relevant mixtures of EDCs. Projects include epidemiological studies in Limpopo province, and studies on reproductive toxicology and ecotoxicolgy.
Contact person: Prof C de Jager.
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 and his team to specifically investigate the effects of 1,1,1-trichloro-2,2-bis(4-chlorophenylethane) (DDT) on male reproductive health. More than 300 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 were clear and the project will be extended. DDT was also shown to have an effect on the sperm chromatin and DNA. In addition to the epidemiological approach, reproductive toxicology studies were performed. A general trend towards 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 (including DDT) showing synergistic effects. These studies were published in internationally peer-reviewed journals during 2007 and are used by the National Department of Health and the WHO in their re-evaluation of the use of DDT and will eventually impact on policy. There are currently several ongoing projects focusing on DDT and health. Prof Riana Bornman and her team focus on urogenital birth defects in newborns and the transfer of chemicals to the unborn baby during pregnancy. Some of the studies focus on environmental health and water quality in malaria areas where DDT is currently used. These are some of 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 the National Department of Health in assessing health risk.
Contact person: Prof C de Jager.
The ultimate goal of this research project was to answer the question of how one should best measure the total potential estrogenic activity in a specific water source. The project evaluated and validated mechanism-based bioassays for the detection and quantification of estrogenic activity of a variety of water matrices including drinking water, surface water and/or treated wastewater effluent; and developed a series of recommendations for the selection of the most appropriate bioassays for a given water source. This was a Global Water Research Coalition (GWRC) project in collaboration with the Water Research Commission (WRC) and the University of Pretoria Water Institute (UPWI). Prof de Jager was the project leader and Dr Natalie Aneck-Hahn a project member, also involved in the analyses of the different samples. The international report was published in 2007 and is the first to evaluate the available tests for different estrogenic activity in different water samples.
Contact person: Prof C de Jager.
The researcher received a postdoctoral fellowship from the International Agency for Research on Cancer. Preliminary results from the 2007 updated dataset of the European Prospective Investigation into Cancer and Nutrition (EPIC) study indicate that total cancer incidence can be reduced by the consumption of 40 g of fruit, 40 g of vegetables of 80 g of fruit and vegetables combined, per day. A significant lower risk for total cancer was also observed with a quintile increase in total fruit, total vegetables and total fruit and vegetable intake. No differences were found for men and women. Total cancer cases include those from head and neck, lung, stomach, kidney, colorectal, breast, ovarian and prostate cancer. The results is based on 31 169 total cancer cases among 335 868 female and 142 603 male participants from 23 centres in ten countries (France, Italy, Spain, The Netherlands, Germany, United Kingdom, Greece, Sweden, Denmark and Norway). Relevance of results to South Africa: These results confirm the health promotion benefits of regular intake of fruit and vegetables in a European study population. Currently it is impossible to say whether the same quantity of fruit and vegetable intake will also have benefits in a developing country setting, such as South Africa.
Contact person: Dr J Wichmann.
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