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This study sought to evaluate the in utero exposure to aluminum and status of selected trace elements in South African women at delivery since aluminum is known to be toxic in all developmental stages even at low concentrations. Serum aluminum was negatively correlated with aluminum in urine, both uncorrected and corrected for creatinine, which suggests the retention of aluminum in body stores. Serum copper and zinc levels were found to be high in this study population. Serum copper levels were negatively correlated with aluminum in serum (β = -0.095; p = 0.05). There was a marginal negative correlation between aluminum levels in serum and manganese levels in whole blood (β = -0.087; p = 0.08). Copper levels in maternal serum were negatively correlated with birth weight and the length of neonates. There were a number of positive correlations between maternal characteristics and birth outcomes. Mothers who consumed root vegetables frequently appeared to be protected from aluminum retention and increased body burden since their serum aluminum levels were found to be significantly lower. The findings of the current study can be used as a baseline for further research on aluminum exposure and its associated interactions and outcomes in vulnerable populations.

Exposure to environmental sources and altered physiological processes of manganese uptake during pregnancy and its possible effect on prenatal and postnatal development are of concern. This study investigates manganese blood levels at the time of delivery across four cohorts of pregnant women residing in coastal communities of South Africa and examines birth outcomes and environmental factors that could influence manganese levels in the study population. The geometric mean (GM) manganese blood levels (MnB) for all women at delivery was 15.2 μg L(-1). Collectively, rural women reported higher MnB concentrations (GM, 16.1 μg L(-1)) than urban women (GM, 13.5 μg L(-1), p < 0.001). Of the 302 cord blood samples drawn from the study participants (rural women only), GM MnB levels reported for three rural sites were 25.8 μg L(-1) (Rural 1), 33.4 μg L(-1) (Rural 2) and 43.0 μg L(-1) (Rural 3) and were twice as high as their respective maternal levels. However, no significant correlations were found between maternal and cord MnB levels across the 3 study areas. Factors associated with elevated maternal MnB levels, after adjusting for gestational age were: women living in a rural area (Rural 2) (p = 0.021); women drinking potable water from an outdoor/communal tap sourced from municipality (p = 0.021); drinking water from river/stream (p = 0.036); younger maternal age (p = 0.026); consuming leafy vegetables once a week (p = 0.034); and elevated maternal blood lead concentrations (PbB) (p = 0.002). The results indicate that MnB concentration in rural women during pregnancy is higher compared to urban women and increases with manganese intake from food and water.

Despite the toxicity and widespread use of manganese (Mn) and lead (Pb) as additives to motor fuels and for other purposes, information regarding human exposure in Africa is very limited. This study investigates the environmental exposures of Mn and Pb in Durban, South Africa, a region that has utilized both metals in gasoline. Airborne metals were sampled as PM(2.5) and PM(10) at three sites, and blood samples were obtained from a population-based sample of 408 school children attending seven schools. In PM(2.5), Mn and Pb concentrations averaged 17±27 ng m(-3) and 77±91 ng m(-3), respectively; Mn concentrations in PM(10) were higher (49±44 ng m(-3)). In blood, Mn concentrations averaged 10.1±3.4 μg L(-1) and 8% of children exceeded 15 μg L(-1), the normal range. Mn concentrations fit a lognormal distribution. Heavier and Indian children had elevated levels. Pb in blood averaged 5.3±2.1 μg dL(-1), and 3.4% of children exceeded 10 μg dL(-1), the guideline level. Pb levels were best fit by a mixed (extreme value) distribution, and boys and children living in industrialized areas of Durban had elevated levels. Although airborne Mn and Pb concentrations were correlated, blood levels were not. A trend analysis shows dramatic decreases of Pb levels in air and children's blood in South Africa, although a sizable fraction of children still exceeds guideline levels. The study's findings suggest that while vehicle exhaust may contribute to exposures of both metals, other sources currently dominate Pb exposures., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Recent studies have suggested that low blood lead level, less than 50 microg L(-1), can influence the neurobehavioral performance of children. In addition, nutritional deficiencies in some essential elements may increase the toxicity of lead, and some essential elements may influence the blood concentrations of lead and other toxic metals. These findings, coupled with the scarcity of available data on some elements in children's blood and the introduction of methylcyclopentadienyl manganese tricarbonyl (MMT) to gasoline, accentuate the need to monitor the concentrations of lead, manganese, and other heavy metals and essential elements in children's blood. This study reports on the multi-element analysis of blood of South African school children using inductively coupled plasma-mass spectrometry (ICP-MS). The sample preparation consisted of a nitric acid/hydrogen peroxide open digestion and subsequent dilution with MilliQ water. The accuracy and precision were evaluated from quintuplet analyses of Seronorm trace elements whole blood reference material and human blood samples. Concentrations of lead, arsenic, manganese, copper, zinc, selenium, cobalt, and chromium in the blood of South African school children were determined. The average values were: lead 56.4 microg L(-1), arsenic 1.53 microg L(-1), manganese 8.48 microg L(-1), copper 1195 microg L(-1), zinc 3431 microg L(-1), selenium 176 microg L(-1), cobalt 0.80 microg L(-1), and chromium 1.25 microg L(-1). The level of lead was in line with some reported lower concentrations. The concentrations of arsenic and manganese were generally lower than those found in the literature. The concentrations of cobalt, copper, selenium, and chromium were higher than those found in other studies, whereas that of zinc was lower.

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.

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.

Five hundred and nine workers at a manganese (Mn) smelting works comprising eight production facilities and 67 external controls were studied cross-sectionally. Exposure measures from personal sampling included inhalable dust, cumulative exposure indices (CEI) and average intensity (INT = CEI/years exposed) calculated for the current job at the smelter and also across all jobs held by subjects. Biological exposure was measured by Mn in the blood (MnB) and urine (MnU) and biological effect was measured by serum prolactin. Average lifetime exposure intensity across all jobs ranged from near 0 (0.06 microg/m3) for unexposed external referents to 5 mg/m3. Atmospheric exposures and MnB and MnU distributions were consistent with published data for both unexposed and smelter workers. Associations between biological exposures and groups defined by atmospheric exposures in the current job were substantial for MnB, less so for MnU and absent for serum prolactin. Random sampling of MnB measurements representative of a group of workers with more than 1-2 years of service in the same job and notionally homogenous exposure conditions could serve as a cross-sectional predictor of atmospheric Mn exposure in the current job, as well as for surveillance of Mn exposure trends over time. Correlations at the individual level were only modest for MnB (33% of the variance in log atmospheric Mn intensity in the current job was explained by log MnB), much worse for MnU (only 7%). However, a receiver operating characteristic (ROC) analysis was performed which showed that it is possible to use a MnB cut-off of 10 microg/l (the 95th percentile in the unexposed) to good effect as a screening tool to discriminate between individual exposures exceeding and falling below a relatively strict atmospheric Mn exposure threshold at the ACGIH threshold limit value (TLV) of 0.2 mg/m3. MnU has no utility as a measure of biological exposure nor does serum prolactin as a measure of biological effect.

Five hundred and nine production workers at a manganese (Mn) smelting works comprising eight production facilities and 67 external controls were studied cross-sectionally for Mn related neuroehavioural effects. Exposure measures from personal sampling included Mn in inhalable dust as cumulative exposure indices (CEI) and average intensity (INT). Biological exposure and biological effect measures included blood (MnB), urine (MnU) manganese and serum prolactin. Endpoints included items from the Swedish nervous system questionnaire (Q16), World Health Organisation neurobehavioural core test battery (WHO NCTB), Swedish performance evaluation system (SPES), Luria-Nebraska (LN), and Danish product development (DPD) test batteries, and a brief clinical examination. Potential confounders and effect modifiers included age, educational level, alcohol and tobacco consumption, neurotoxic exposures in previous work, past medical history, previous head injury and home language. Associations were evaluated by multiple linear and logistic regression modelling. Modelling assumptions were tested. Average exposure intensity across all jobs ranged from near 0 (0.06 microg/m3) for external controls to 5.08 mg/m3 for inhalable Mn, and was greater than the ACGIH TLV for 69% of subjects. Results from the large number of tests performed resolved into three groups. Group 1 shows differences between external unexposed referents and all the exposed and/or differences between internal low exposed referents and the rest of the exposed but no further exposure-response relationships. It includes the Santa Ana, Benton and digit-span tests from the WHO NCTB; the hand tapping and endurance tapping tests from the SPES; Luria-Nebraska item 2L; questionnaire items tired, depressed, irritated, having to take notes in order to remember things, and subjects' perception that they had sex less often than normal; a test of clinical abnormality; and increased sway under two conditions (eyes open without foot insulation, eyes open with foot insulation). Group 2 shows the presence of a more substantive exposure-response relationship. It consists of only two tests: and includes the WHO digit-symbol test (although the major impact is at low exposure and therefore counterintuitive, arguably placing this test in group 3) and the LN item 1R which has a step to a poorer score at high exposure. Group 3 contains the overwhelming majority of test results (almost all the questionnaire items, almost all the DPD tests including tremor, sway and diadochokinesia, and serum prolactin) which were either null or counterintuitive (did not make sense). The CEI was the strongest predictor of test abnormalities, except for the clinical test which was more strongly associated with blood manganese. Despite a comprehensive range of endpoints, and levels of exposure ranging from environmental to industrial, this large study of Mn workers found little convincing evidence for a continuum of effects, contributing further questions to current debates about the adequacy of the current ACGIH TLV.

Occupational exposure to airborne manganese dust has been shown to produce adverse effects on the central nervous system. Four hundred and eighty-nine blue and white collar manganese mineworkers from South Africa were studied cross-sectionally to investigate the nervous system effects of medium to low occupational manganese exposures. The different facilities included underground mines, surface processing plants, and office locations. A job exposure matrix was constructed using routine occupational hygiene data. Exposure variables included years of service, a cumulative exposure index (CEI) and average intensity of exposure (AINT) across all jobs, and blood manganese. Endpoints included items from the Q16, WHO-NCTB, SPES, and Luria-Nebraska test batteries, and a brief clinical examination. Potential confounders and effect modifiers included age, level of education, past medical history including previous head injury, previous neurotoxic job exposures, tobacco use, alcohol use and home language. Associations were evaluated by multiple linear and logistic regression modeling. Average exposure intensity across all jobs was 0.21mg/m(3) manganese dust. Multivariate analyses showed that none of the symptom nor test results were associated with any measure of exposure including blood manganese, after adjustment for confounders. This relatively large null study indicates that manganese miners exposed on average across all jobs to MnO(2) at levels near the American Conference of Governmental Industrial Hygienists Threshold Limit Value (ACGIH TLV) are unlikely to have a subclinical neurotoxicity problem.