Browsing by Subject "Environmental Health"

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    An assessment of the extent of environmental mercury contamination in the vicinity of Thor Chemicals, Cato Ridge, Kwa Zulu-Natal, South Africa and the subsequent health risk communities consuming fish in the area are exposed to
    (1999) Oosthuizen, Jacques De Villiers; Ehrlich, Rodney I
    Environmental mercury pollution of the Valley of a Thousand Hills area of KwaZulu-Natal, South Africa, in particular the river system below the Thor Chemicals mercury recycling plant, has been a topic of heated debate for a number of years. Thor Chemicals was established as a mercury recycling plant in the mid-1980' s and it processed mercury waste imported from various countries. A number of factory workers were subsequently exposed to high levels of mercury vapour causing the death of a worker. Upon investigation it was found that in addition to the occupational exposures of workers, mercury waste had been discharged into the river systems of the Valley of a Thousand Hills. During the 1998 South African Parliamentary session, questions were raised regarding the lack of adequate monitoring and research directed at quantifying human health risks in the region. A number of Government departments were accused of apathy and incompetence in adequately addressing the issue. Fish forms an important part of the diet of the local community living in the Valley of a Thousand Hills. Children, in particular, are frequently observed fishing in the rivers, thus placing these individuals at risk should the fish be contaminated with mercury. The aims of this study were: to determine the extent of environmental mercury pollution of the river system downstream from the Thor Chemicals plant, and to quantify the human health risk associated with fish consumption in the region. Samples of streambed sediment, algae, cattle hair, fish and human hair, were obtained from the study area as well as from a control area upstream from the Thor Chemicals plant. These were analysed to determine the concentration of mercury in each sample. Mercury levels in the study group were compared to mercury levels in the control areas.
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    Open Access
    Mycotoxin health risk assessment modelling among maize-subsistence farmers living in Centane, Eastern Cape Province, South Africa
    (2022) Burger, Hester-Mari; Rother, Hanna-Andrea
    Harmful mycotoxins such as fumonisin B (FB), deoxynivalenol (DON), and zearalenone (ZEA), produced by ubiquitous food-borne fungal species, are known to contaminate maize crops from subsistence farming areas in Centane, Eastern Cape Province (EC), South Africa. The daily consumption of home-grown maize in these areas has resulted in FB exposure of five to ten times above the recommended provisional maximum tolerable daily intake (PMTDI) of 2 µg kg-1 body weight day-1 , as set by The Joint FAO/WHO Expert Committee on Food Additives. From a public health perspective, not only can these mycotoxins cause various human diseases but also impact food security. For this purpose, mycotoxin risk assessment among maizesubsistence farmers is critical to ensure evidence-based risk management. Currently, in resources poor settings, a deterministic risk assessment approach remains the easiest and most accessible. This approach, based on epidemiological data, includes using a total mean mycotoxin level (µg kg-1 ) multiplied by the individual total mean dry/raw maize intake in g day-1 divided by body weight (kg) and expressed as a probable daily intake (PDI). The resultant PDI is thereafter compared to the relevant mycotoxin PMTDI to determine the risk. However, this type of assessment remains one-dimensional and can only quantify risk. To address this limitation, the current study was aimed at developing a mycotoxin risk assessment model that not only quantifies the risk of exposure to multi-mycotoxins (FB, DON, and ZEA) but it is also interactive. The new model was based on the Mycotoxin Risk Assessment Model (MYCORAM) that was originally developed for South African commercial maize consumers and referred to as the MYCORAM-II. The overall purpose of the MYCORAM-II is to assess the percentage of maize consumers above the relevant mycotoxins PMTDI. In the current study, a multiphase study design was used to develop and evaluate the model consisting of phase 1) dietary maize intake, body weight data collection, phase 2) the development of dietary dry maize intake per body weight categories, phases 3 and 4) mycotoxin levels data and the development of the MYCORAM-II, phase 5) evaluation of the MYCORAM-II using published mycotoxin levels in home-grown maize from Centane, and phase 6) to assess the appropriateness of the national maximum safety levels as set by the South African Department of Health for FB and DON in dry maize. The development of the model was limited to the availability of secondary data, its validity, and the type of data that has been collected and published from studies conducted over the past 10 years in rural maize-subsistence farming areas in EC, South Africa. Applying mycotoxin levels in home-grown maize from Centane to the MYCORAM-II indicated that for total FB between 80-90% of maize, consumers were above its PMTDI based on overall higher levels of FB. In comparison, DON and ZEA with their lower levels in home-grown maize resulted in a lower percentage of consumers above the respective PMTDIs. The MYCORAM-II also indicated that the South African national maximum safety levels will not protect subsistence maize consumers between (89% and 90% will be at risk). In addition, the MYCORAM-II indicated differential risk scenarios when using published data from African countries. Overall, the MYCORAM-II highlighted the distinct roles of FB levels in home-grown maize, the number of positive samples, and maize intake practices. Despite the limitation of the MYCORAM-II, its simplicity and interactive function render it useful to describe multi-mycotoxin exposure among subsistence maize farmers not only in Centane, EC, but also in Africa. Its application can also be expanded towards developing population-specific safety levels, facilitating decision-making during risk management, and the evaluation of appropriate public health interventions aimed at reducing mycotoxin exposure.
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    Risk factors and the effectiveness of back belts in the prevention of back pain amongst forklift drivers subject to whole body vibration exposure
    (2000) Joubert, Darren Mark; London, Leslie
    Motivation: Back pain is a major cause of absenteeism, lost work time and increased compensation and medical costs amongst workers and has been estimated to cost $20 billion annually in the United States. Back pain has long been associated with the driving of forklifts, and is a complex area of occupational health and safety, having many risk factors leading to musculo-skeletal injury. The health effects in this occupational group in South Africa, could be affecting upwards of 90 000 forklift drivers, and has a great direct and indirect influence on people's health at work as well as productivity and the economy. Purpose: To characterise the problem of back pain amongst forklift drivers with a view to reducing the morbidity from back pain, by evaluating the effectiveness or the use of back belts. Aim: To identify risk factors associated with back pain amongst forklift drivers at Portnet (handling wharf side cargo) in two cohorts of forklift drivers one using back belts and one control group, and to evaluate the relationship between back pain, the occupational environment (i.e.: forklift driving) and other associated factors, in order to establish the effectiveness of back belts in decreasing the severity and prevalence of back pain amongst forklift drivers. Objectives: 1.) To describe demographic and other relevant back pain risk factors in the two cohorts and to identify any significant differences between them. 2.) To characterise the compliance and frequency of use of the back belts by the user group. 3.) To measure vibration experienced in typical driving activities in the study population in order to characterise whole-body vibration exposures of the study subjects. 4.) To ascertain opinions and beliefs regarding back belts amongst users. 5.) To analyse, characterise and determine if any significant differences exist between the two groups as to the prevalence and severity of back pain, and what factors are associated with increased risk of back pain. Specifically to identify whether (a.) The frequency and/or intensity of use of back belts are associated with reduced risk for back pain, when controlling for all other risk factors, and (b.) Whether other factors modify this relationship. Study Design: Cross Sectional Study Design Subjects: Drivers of 3, 4, 4.5 and 5 ton forklifts in the permanent employment of Portnet, Durban, from the Point, Maydon Wharf (back belt group) and Combi-Terminal (control group) areas. Main Outcome Measures: Onset of back pain after starting driving, prevalence of regular back pain (ever), point prevalence (pain today), 1 year prevalence, severity of back pain, duration of pain, and treatment/medication sought for back pain. Results: The majority of forklift drivers (89%) in the study suffer from chronic back pain that is of a constant severity, and is significantly linked to the driving activities. The back belt wearers were more likely to suffer from back pain then the non-users (92% vs 80%). However, the belt wearers reported less severe pain than the control group, which could indicate the presence of a placebo effect related to the belt use. The belt users were more likely to suffer from pain of a longer duration, with less fluctuation in severity than the controls, and therefore a more constant type of pain (44% vs 41 %). The majority of bell wearers expressed the belief that the belts helped to reduce the back pain (81%). However, more objective measures do not bear out this conclusion when prevalence and severity of pain are compared to the control group. Drivers with back pain were more likely to wear the back belts and compliance was reduced as the prevalence of pain was reduced. These results may have been confounded by variations in the whole-body vibration exposure in the various test areas, and the inability to characterise individual whole-body vibration exposures and dose-response relationships. Conclusion: The prevalence of back pain in this study was high, with most drivers suffering from pain in the lower back region (79%), which was characterised as constant or chronic pain experienced either during or shortly after driving. Whole-body vibration levels were high in all test areas (1.9 m/s⁻², 1.3 m/s⁻² and 1.1 m/s⁻² predicted), and consistently exceeded the EEC machinery directive standards of 0.5 m/s⁻². Compliance with the use of back belts amongst drivers was high (90%), with most drivers (76%) wearing the belts on a regular basis whilst driving. The evidence for the effectiveness of back belts as a control measure against whole-body vibration remains obscure, and other more tested controls such as engineering, administrative and training of drivers should be implemented to address the problem following a holistic approach.