Biomedical subjects

Angela Mathee

Publications and source records attributed to Angela Mathee.

8 recordsLinked to original sources

PubMed2006

Examining the association between blood manganese and lead levels in schoolchildren in four selected regions of South Africa.

This study assessed the possibility of relationship between manganese and lead levels in blood in schoolchildren residing in different geographical regions of South Africa. A cross-sectional survey was carried out in schools of three cities: Cape Town (11 schools), Johannesburg (10 schools), Kimberley (six schools) and in the Northern Cape in three rural sites (four schools). A total of 1282 venous blood samples were collected from grade one children. The relationships between blood manganese and blood lead levels (treating each in turn as the response variable in order to adjust for the effect of confounding variables) were investigated by fitting mixed models. Mixed models were fitted with natural log (manganese concentration) as the response variable, and blood lead level as the principal explanatory factor. The model also included terms for centre and a centre by lead interaction and examined potential confounders. The important confounders were found to be gender, race and whether there was paint peeling from the outside walls. There was a significant centre by lead interaction (P<0.0001) with the effect of lead on ln(Mn) being different in the various centres. Mixed models fitted with blood lead level as the response variable and blood manganese as the principal explanatory factor, with terms for centre, a centre by manganese interaction and potential confounders, again found overwhelming evidence (P<0.0001) of a centre by manganese interaction. The study found great variability in both blood lead and manganese levels, both within and between sites, and there was not a consistent relationship between the two metals in the four sites.

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PubMed2005

Reductions in blood lead levels among school children following the introduction of unleaded petrol in South Africa.

Epidemiological studies have indicated that in the 1980s and early 1990s (a period in which petrol lead concentrations in South Africa ranged from 0.836 to 0.4 g/L), large proportions of urban South African children were at risk of excessive exposure to environmental lead. In 1991, when the maximum permissible petrol lead concentration in the country equaled 0.4 g/L, a study determined that the mean blood lead level among children attending inner city schools in the Cape Peninsula equaled 16 microg/dL, with well over 90% of children having blood lead levels equaling or exceeding the internationally accepted guideline level of 10 microg/dL. Socio economic status, housing conditions, and proximity of children's schools and homes to heavily trafficked roads were among the factors significantly associated with blood lead concentrations. In 1996, unleaded petrol was introduced in South Africa. A study undertaken in 2002 (at the same schools as in 1991), when unleaded petrol constituted around 30% of the market share of petrol in the country, has shown significant reductions in the mean blood lead concentration among Cape Peninsula inner city children and in the proportion of children with elevated blood lead levels. The mean blood lead level for the total sample (n = 429) of children whose mean age equaled 7 years (range: 5-11 years) was 6.4 microg/dL (range: 1.0-24.5 microg/dL) and 10% of children had blood lead levels equalling or exceeding 10 microg/dL. The mean blood lead levels among children attending schools in an inner city and in a less heavily trafficked periurban suburb were 6.9 and 4.8 microg/dL, respectively.

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PubMed2005

Blood manganese concentrations among first-grade schoolchildren in two South African cities.

Little information exists on the environmental exposures to low levels of organometallic manganese (a principal combustion product from manganese-containing fuel additives) and public health. This study was undertaken to establish biological and environmental levels of manganese among first-grade schoolchildren in the South African cities of Johannesburg and Cape Town. The study was undertaken subsequent to partial introduction of the manganese-containing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) to South African petrol in the Johannesburg region only, about 24 months prior to the commencement of the study, and in anticipation of possible future increases in MMT use in the rest of the country. This study involved the measurement of manganese concentrations in the blood of the total number of 814 of grade one schoolchildren (430 and 384 in Cape Town and Johannesburg, respectively), and in water supplies, soil, and classroom dust at a total number of 21 participating schools. The results indicated higher concentrations of manganese in school soil (P=0.0007) and dust (P=0.0071) samples from Johannesburg relative to Cape Town. Similarly, the mean blood manganese concentration in Johannesburg study subjects (9.80 microg/L, SD 3.59) was significantly higher than that in Cape Town study subjects (6.74 microg/L, SD 3.47), after allowing for the clustering effect within schools and adjusting for the confounding effect of population group (P<0.0001). The blood manganese levels of 4.2% and 12.5% of children in Cape Town and Johannesburg, respectively, equaled or exceeded 14 microg/L, the upper normal reference value specified by the Agency for Toxic Substances Disease Registry (ATSDR, 2000). Importantly, levels of manganese in blood were found to be significantly associated with concentrations of manganese in classroom dust at schools.

Child↗

PubMed2005

Assessing child time-activity patterns in relation to indoor cooking fires in developing countries: a methodological comparison.

Indoor air pollution, caused by the indoor burning of biomass fuels, has been associated with an increased risk of child acute respiratory infections in developing countries. The amount of time that children spend in proximity to fires is a crucial determinant of the health impact of indoor air pollution. Researchers are reliant on social scientific methods to assess exposure based on child location patterns in relation to indoor fires. The inappropriate use of methods could lead to misclassification of exposure. The aim of this paper is to compare two methods (observations and questionnaire interview) with video analysis (which is thought to offer a more accurate assessment of exposure) in rural South African villages. Compared to video analysis, results show that observations may underestimate the amount of time that children spend very close (within 1.5 m) to fires. This is possibly due to reactivity caused by the presence of an observer. The questionnaire interview offers a more accurate assessment of the amounts of time that children spend within 1.5 m of fires at the expense of a detailed behavioural analysis. By drawing on the strengths and weaknesses of each, this paper discusses the appropriateness of methods to different research contexts.

Air Pollution, Indoor↗

PubMed2004

A behavioral intervention to reduce child exposure to indoor air pollution: identifying possible target behaviors.

Indoor air pollution has been causally linked to acute lower respiratory infections in children younger than 5. The aim of this study was to identify target behaviors for a behavioral intervention to reduce child exposure to indoor air pollution by attempting to answer two research questions: Which behaviors are protective of child respiratory health in the study context? and Which behaviors do mothers recommend to reduce their children's exposure to indoor air pollution? Observations and interviews were conducted with 67 mother-child combinations. The authors recommend that four behavioral clusters should be considered for the main intervention. These are to improve stove maintenance practices, to increase the duration that two ventilation sources are opened while a fire is burning, to reduce the time that children spend close to burning fires, and to reduce the duration of solid fuel burning.

Air Pollution, Indoor↗

PubMed2003

A study of pediatric blood lead levels in a lead mining area in South Africa.

This study aimed to determine the blood lead distributions among young children in the lead mining town of Aggeneys in South Africa's Northern Cape Province, and in the comparison community of Pella, about 40 Km away. A further objective of the study was to explore factors associated with elevated blood lead levels. Children aged between 6 and 10 years (average age, 8 years) were studied, 86 from Aggeneys and 68 from Pella. The results showed that blood lead levels among the children of Aggeneys averaged around 16 microg/dL, while in Pella the mean blood lead level equaled 13 microg/dL. Overall, children with raised blood lead levels performed less well at school relative to other children. Within Aggeneys, fathers of "high" lead children tended to shower at work rather than at home, which may have been insufficient to prevent lead from being transported into the home. In conclusion, more stringent environmental control measures are needed, as well as stricter personal hygiene measures, to prevent childhood lead exposure in the mining community.

Child↗

PubMed2003

The health impact of environmental pollutants: a special focus on lead exposure in South Africa.

Studies have shown blood lead levels of some children in South Africa at levels of health concern. New studies show even relatively low lead levels to have detrimental effects on cognitive function in young children. Large numbers of South African inner-city and other children have been shown to have unacceptably high blood lead levels. Studies indicate that blood lead levels of children living in South Africa's urban areas are higher than those of children in most developed countries, including Great Britain, Europe, and the United States. Although data and reported studies are very sparse, mean blood lead levels of approximately 15 microg/dl have been reported in children. Elevated blood lead levels were associated with socioeconomic status and housing conditions. Key environmental risk factors for elevated blood levels were contaminated soil and dust in the urban environment, and the still large number of automobiles using leaded gasoline. In view of emerging evidence linking lead at increasingly lower levels to adverse effects in children, the South African government is taking actions to reduce lead exposure among vulnerable groups. Currently, South Africa has no national lead surveillance program. The government, therefore, has developed international and regional partnerships to prevent and address the problem of lead exposure.

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PubMedDate not supplied

Lead poisoning in South African children: the hazard is at home.

Lead is a toxic heavy metal that has been used extensively in modern society, causing widespread environmental contamination even in isolated parts of the world. Irrefutable evidence associates lead at different exposure levels with a wide spectrum of health and social effects, including mild intellectual impairment, hyperactivity, shortened concentration span, poor school performance, violent/aggressive behavior, and hearing loss. Lead has an impact on virtually all organ systems, including the heart, brain, liver, kidneys, and circulatory system, resulting in coma and death in severe cases. In recent years, a consensus was reached regarding the absence of a threshold for the key health effects associated with lead exposure and the permanent and irreversible nature of many health and social consequences of lead exposure. The public health problem of environmental lead exposure has been widely investigated in developed countries like the United States of America, where actions taken have led to significant reductions in children's blood lead concentrations. In contrast, there is a relative dearth of information and action regarding lead poisoning in developing countries, particularly in African countries, despite evidence of widespread and excessive childhood lead exposure. In this paper, we will review the information from available published papers, the 'grey literature', and unpublished reports to give an overview of lead exposure in South African children over the past two decades, with particular emphasis on sources of exposure in the home environment.

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