Faculty of Health Sciences
School of Health Systems and Public Health
Selected Highlights from Research Findings
Crystalline silica dust is an important environmental hazard in the mining industry. If this dust is inhaled on a frequent basis, it can cause silicosis – an incurable, chronic lung disease. This danger provides a powerful incentive for the development of environmental monitoring tools capable of detecting the signs of silica dust exposure in people before it gives rise to the disease.
The quest for such tools is complicated by a number of factors. In possibility is that a test might fail to distinguish between individuals who already suffer from silicosis, but are no longer exposed to silica dust, and those who are currently exposed and are therefore at risk of developing the disease.
The outcome of a test might also be confounded by other factors that affect lung condition, such as smoking and HIV infection. A promising avenue for the development of a tool for detecting silica dust exposure is through the use of biomarkers – cellular products or constituents that indicate changes in an organism.
Previous research had identified a number of biomarkers that could potentially serve as indicators of silica dust exposure.
In a project funded by the Safety in Mines Research Advisory Committee and led by Proff Girdler-Brown of the University and Jill Murray of the University of the Witwatersrand, these biomarkers were measured in a group of 120 volunteers.
The members of this group differed along a number of dimensions, including current exposure to silica dust, diagnosis with respect to silicosis and HIV status. It was found that two of the biomarkers had significantly reduced levels in silica-exposed groups, but were unaffected by smoking, HIV status or the presence of clinical silicosis.
Further research is currently underway to develop a standardised monitoring protocol based on these biomarkers
Contact person: Prof BV Girdler-Brown.
Occupational lung diseases represent one of the most significant threats to the health and safety of miners. Examples of such diseases include pulmonary tuberculosis (pTB), chronic obstructive pulmonary disease (COPD) and silicosis.
Little information is available on occupational lung diseases among platinum miners. In order to address this shortcoming, Prof Brendan Girdler-Brown of the School of Health Systems and Public Health conducted a study aimed at documenting existing knowledge about factors affecting the risk for occupational lung diseases among platinum group metal (PGM) miners.
This review of prior research was supplemented by two pieces of empirical research: an analysis of autopsy findings in a group of miners who died on a platinum mine, and a cross-sectional study of the burden of occupational lung diseases among current PGM miners in South Africa.
The results of the study, which was conducted during 2005 and 2006 with funding from the Safety in Mines Research Advisory Committee of the Department of Minerals and Energy, revealed that routinely monitored levels of air pollutants were well below the occupational exposure limits recommended for workers.
However, it was found that the methods specified by the Department of Minerals and Energy for monitoring such pollutants may result in under- or over-estimation of exposure levels.
The study also identified a need for improving the completeness and accuracy of record-keeping with regard to previous work histories. The importance of such information derives from the fact that the risk associated with various types of occupational lung diseases depends on the type of mine.
Silicosis, for instance, is more likely to occur among persons with current or previous gold mining exposure than among those who have only worked in platinum mines. The prevalence of pulmonary tuberculosis, on the other hand, was not found to differ between those with and without a previous gold-mining history
Contact person: Prof BV Girdler-Brown.
South Africa’s high crime statistics have regularly featured in the news recently, with a very high incidence of murder, rape and child abuse. Research has indicated that as many as 28% of female rape victims are bitten during the course of the attack, and that biting is common during all violent crimes.
Bite mark analysis can be instrumental in identifying the perpetrators of these violent crimes. Part of the recognised protocol for investigating such cases therefore involves taking impressions of the bite marks for macroscopic and microscopic analysis.
Since bite mark impressions form an integral link in the chain of evidence, it is vital that the materials used to take such impressions maintain their dimensional stability over time.
However, research conducted by Prof Herman Bernitz at the Department of Oral Pathology and Oral Biology has indicated that the impression material most commonly used in forensic dentistry does not meet this criterion.
When dentists are asked to take impressions of bite marks, they tend to use the material they already have in stock. Impregum is one of the most popular impressions materials used in dentistry, as it is highly suited to crown and bridgework.
This material is therefore also often used to take impressions of bite marks in skin– although the product was not designed with this primary use in mind.
Bernitz and his colleagues garnered clear evidence in the field and research laboratory that the polyether impression material, Impregum was unstable after coming in contact with skin: such impressions tend to alter their physical properties with time, becoming sticky and unusable as evidence.
The results of their study, which has generated a certain amount of controversy, led to the recommendation that Impregum should not be used in applications where the impression material will come into contact with skin, especially where such impressions will need to be stored for any length of time.
The recommendation is that it not be used in forensic cases to take impressions of skin for the purpose of collecting bite mark evidence
Contact person: Prof BV Girdler-Brown.
Asthma and eczema are becoming more common among children worldwide. However, little research has been conducted to determine whether this trend is reflected in rural provinces in South Africa.
In order to address this gap in scientific knowledge, Dr Janine Wichmann and her colleagues at the School of Health Systems and Public Health have conducted a population-based study involving nearly seven thousand children living in a sixty-kilometre radius around Polokwane in the Limpopo Province. The children represented two age groups: 6-7 and 13-14 year of age.
Data for the study were collected by means of questionnaires; these included items designed to determine whether or not a child had experienced symptoms of asthma, eczema or hay fever within the last twelve months.
The questionnaires also elicited information on respondents’ exposure to tobacco smoke, polluting fuels (such as smoke from wood or charcoal fires) and other environmental factors that might aggravate asthmatic symptoms.
The findings of the study included the surprising result that children living in households using a combination of clean and polluting fuels have a lower prevalence of asthma than children in households who rely exclusively on clean fuels.
This trend may be explained by the fact that households using only clean fuel tend to have higher socio-economic status than those who use polluting fuels as well.
The mystery remains, however, as to why the incidence of asthmatic symptoms increases with rising socio-economic status. It might be that asthma is under-diagnosed and over-diagnosed in lower and higher socio-economic status groups, respectively. Wichmann et al. also cite previous research suggesting that stress and other factors associated with a westernised (and usually more prosperous) lifestyle might increase children’s susceptibility to asthma
Contact person: Dr J Wichmann.
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