Causes of lead toxicity in a Nigerian city

High blood lead levels of children in a gold mining community in Osun State, Nigeria: an urgent call for action

BACKGROUND

Environmental exposure from artisanal gold mining activities is a major risk for high blood lead levels (BLLs) in children. Over the last decade, artisanal gold mining activities have been on a sharp increase in some parts of Nigeria. This study compared BLLs of children in the mining community of Itagunmodi and a 50-km distant non-mining community of Imesi-Ile, Osun State, Nigeria.

METHODS

This community-based study investigated 234 apparently healthy children, with 117 each from Itagunmodi and Imesi-Ile. Relevant history, examination and laboratory findings including BLLs were recorded and analysed.

RESULTS

All participants had BLLs above the cut-off value of 5 µg/dl. However, the mean BLL of subjects living in the gold-mining community (24.2±5.3 µg/dl) was significantly higher than for children in the non-mining area of Imesi-Ile (19.5±6.4 µg/dl; p<0.001). Children in the gold mining community were 3.07 times more likely to have a BLL ≥20 µg/dl than those in the non-mining environment (odds ratio [OR] 3.07 [95% confidence interval {CI} 1.79 to 5.2], p<0.001). Similarly, the odds of having a BLL ≥30 µg/dl was 7.84 times more likely among children living in gold mining Itagunmodi than in Imesi-Ile (OR 7.84 [95% CI 2.32 to 26.46], p<0.0001). BLL was not associated with socio-economic and nutritional status of the participants.

CONCLUSIONS

In addition to introduction and enforcement of safe mining practices, regular screening for lead toxicity is advocated for children in these communities.

Blood lead levels in children residing in a 115-year old urban settlement in Harare, Zimbabwe: a cross sectional study

BACKGROUND

Elemental lead (Pb) toxicity in children, irreversibly affects their growth and development. We assessed the prevalence of high blood Pb levels (BLL) in children living in a potentially high risk residential area and also assessed Pb levels in environmental specimens.

METHODS

This cross sectional study measured blood lead levels (BLL) in 86children living in Mbare, a densely populated suburb in Harare, Zimbabwe, characterised by dwellings progressively constructed from 1907 through to the 1940s, before the ban of leaded paint. Study participants of both genders were under 6 years of age. Potential risk factors of Pb poisoning were assessed. Pb levels were also assessed in soil, water and paint chip specimens from the study area.

RESULTS

The mean (standard deviation) BLL was 4.3 ± 0.75 g/dL. Twelve (13.95%) participants had BLL of > 5.0ug/dL. Our results showed no significant association between BLL and household income, participant behaviour/habits/activities, sources of drinking water, and the types of cookware used to prepare meals in their households.

CONCLUSION

Mean BLL observed in the current study were higher compared to those of children of similar age groups in the United States, suggesting that Pb contamination may be more ubiquitous in the Mbare flats area, potentially predisposing these children to impaired development.

Sources of Lead Exposure in West Africa

This commentary is an investigation of sources of lead (Pb) exposure in West Africa. Pb is generally acknowledged as one of the most widespread environmental health hazards in West Africa, and there is heightened concern over adverse health effects at various levels of exposure (at doses once considered safe) in the West African region. A literature review for the possible health implications of Pb exposure on human health showed nervous system dysfunction, anemia, and potential cognitive diseases as the major health issues among children, while adults were found to suffer more from cardiovascular dysfunction, neurological decline, and reproductive diseases. Despite a decline in blood lead levels (BLLs), lead exposure continues to be a major public health concern as no level of Pb exposure can be considered safe. Moreover, lowering BLLs entails identifying various lead sources such as gasoline emissions, leaded paint, canned foods, and beverages, as well as plausible biological pathways of lead exposure and response. However, only countries such as Nigeria and Ghana have extensive research available regarding the different sources of Pb exposure. Further, it is not apparent which country is affected the most by Pb exposure. Therefore, this commentary was aimed to explore different literature sources to describe and list the different sources of Pb exposure in 15 West African countries. The findings indicated water, food, and occupational exposure as the major sources of Pb exposure in the region. People with occupations such as e-waste and Pb acid battery recycling, auto mechanics, fuel attending, welding, electronic repairing, farming/spraying, and mining were found to be at immediate risk. Tobacco, spices and paints constituted additional potential sources of exposure. For residents living near landfills or urban area, the major sources of Pb exposure were soil, air, and dust particles. The review revealed a vast research gap on the sources and implications of Pb exposure. Exposure to Pb could further increase due to uncontrolled traffic, urban growth, inadequate urban planning, and the inadequate enforcement of regulations. Therefore, more extensive research on the changing trends of Pb exposure among West African populations is needed.

Nutritional rickets - Vitamin D and beyond

Vitamin D deficiency has been considered to be the cause of nutritional rickets for most of the past century. During the past two decades, however, it has become clear that nutritional rickets may be caused by vitamin D deficiency or by dietary insufficiency of calcium. The combined deficiencies of calcium and vitamin D interact, and several other factors are also relevant in the pathogenesis of nutritional rickets.

Modulatory efficacy of Punica granatum L. powder ethanol extract (PLEE) on lead acetate-induced hepatic and renal toxicity

Background

Pomegranate powder derived from pomegranate fruit contains phytochemicals chief of which is ellagitannins. Owing to their high antioxidative capabilities we investigated its efficacy against lead acetate induced hepatic and renal toxicity.

Methods

Pomegranate powder (500 g) was procured and soaked in 1 Litre of ethanol for three days, its filtrate was concentrated and freeze dried to form Punica granatum L. ethanol extract (PLEE). Thirty (30) male albino Wistar rats with average weight between 140 ± 20 g were used for this study. They were equally shared into 6 groups with 5 animals each; A: Control; B: Lead acetate only C: Lead acetate + PLEE (1); D: Lead acetate + PLEE (2); E: PLEE (1) and F: PLEE (2). Serum, liver and kidney samples were obtained for biochemical assays. The integrity of liver and kidney tissues were also accessed.

Results

Lead administration resulted in marked elevations in liver transaminases in serum and liver as well as a significant increase in kidney function markers in the serum and kidney (p < 0.05). There was also a significant decline in average body weight, antioxidant markers in the liver and kidney of Wistar rats while there was a significant increase in lipid peroxidation levels in both liver and kidney. However, administration of PLEE at different doses significantly modulated these changes.

Conclusion

Lead acetate administration led to hepatic and renal toxicity as evident by alterations in liver and kidney function markers, antioxidant status and tissue integrity. However, PLEE can combat these toxicities.

Risk Analysis Approaches to Evaluating Health Impacts from Land-Based Pollution in Low- and Middle-Income Countries

Risk analysis offers a useful framework for evaluating and managing environmental health risks across different settings. In this Perspective, we question whether the principles and practice of risk analysis could be beneficial in the context of land-based pollution in low- and middle-income countries (LMICs) to better support risk-based decision making. Specifically, potential health and economic impacts from land-based pollution in LMICs has become an increasing issue of concern due to widespread environmental contamination from active and legacy operations, particularly informal activities that are becoming increasingly dispersed throughout communities, such as used lead acid battery recycling, artisanal and small-scale gold mining, and small-scale tanneries. However, the overall magnitude and scale of the public health problem arising from these sources remains highly uncertain and poorly characterized and cannot be compared to land-based pollution in high-income countries due to unique factors. This lack of knowledge has negatively affected the political priority and level of funding for risk mitigation actions targeting land-based pollution in these countries. Our primary objective is to raise further awareness of this emerging issue among risk analysts and decisionmakers and to advocate for more robust and focused research. Here, we highlight the types of industries and activities contributing to land-based pollution in LMICs and describe key findings and knowledge and data gaps that have hindered a fuller understanding of this issue. We also discuss how several risk assessment and risk management approaches might be useful in this resource-constrained context. We conclude that a combination of risk analysis approaches may be worthwhile, but more work is needed to determine which methods or tools will be most informative, technically feasible, and cost-effective for identifying, prioritizing, and mitigating land-based pollution in LMICs. Affected researchers, funding agencies, and local or national governments will need to work together to develop improved study designs and risk mitigation strategies.

Detection, Distribution and Health Risk Assessment of Toxic Heavy Metals/Metalloids, Arsenic, Cadmium, and Lead in Goat Carcasses Processed for Human Consumption in South-Eastern Nigeria

Notwithstanding the increased toxic heavy metals/metalloids (THMs) accumulation in (edible) organs owed to goat′s feeding habit and anthropogenic activities, the chevon remains increasingly relished as a special delicacy in Nigeria. Specific to the South-Eastern region, however, there is paucity of relevant data regarding the prevalence of THMs in goat carcasses processed for human consumption. This work was, therefore, aimed to investigate the detection, distribution and health risk assessment of THMs in goat carcass processed for human consumption in South-Eastern Nigeria. To achieve this, a total of 450 meat samples (kidney, liver and muscle) were evaluated from 150 randomly selected goat carcasses processed in two major slaughterhouses in Enugu State. The detection, distribution, as well as health risk assessment parameters followed standard procedures. Results revealed that at least one THM was detected in 56% of the carcasses. Mean concentrations of arsenic (As) were 0.53 ± 0.10 mg/kg, 0.57 ± 0.09 mg/kg and 0.45 ± 0.08 mg/kg, lead (Pb) were 0.48 ± 0.38 mg/kg, 0.45 ± 0.24 mg/kg and 0.82 ± 0.39 mg/kg, cadmium (Cd) was 0.06 ± 0.32 mg/kg, 0.02 ± 0.00 mg/kg, and 0.02 ± 0.00 mg/kg for kidney, liver and muscle tissues, respectively. The estimated daily intakes (EDI) for all THMs were above the recommended safe limits. The target hazard quotient (THQ) and hazard index (HI) computed for all As, Cd and Pb fell below unity in all the studied organs, which indicated no non-carcinogenic risks. Curtailing the anthropogenic activities that aid the THM-contamination in goat production/processing lines is recommended. Screening for THM-contamination in Nigerian slaughterhouses is imperative, so as to ascertain the toxicological safety of meats intended for human consumption.

Antioxidative properties of Ocimum gratissimum alters Lead acetate induced oxidative damage in lymphoid tissues and hematological parameters of adult Wistar rats

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Chronic lead toxicity was induced in male rats by oral administration of lead acetate.

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Effect of Ocimum gratissimum in lead acetate toxicity on spleen, thymus, and blood.

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Oral lead acetate administration led to oxidative damage in spleen, thymus and blood.

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Ocimum gratissimum extract reversed oxidative stress and enhanced antioxidant enzymes.

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Ocimum gratissimum averts lead acetate-induced toxicity in the blood, thymus and spleen.

Lead exposure is a well-known environmental hazard. Its accumulation in humans may pose a danger to health. The present study investigated the beneficial effect of Ocimum gratissimum extract (OG) in reducing lead acetate (LA) induced oxidative damage in the spleen, thymus, and hematological indices. We employed an in vivo model of LA induced Wistar rats and administered 125 mg/kg/bw and 250 mg/kg/bw of OG extracts respectively. Our control groups were divided into 2; the first group received normal saline, feed, and water while the second group was administered OG extracts only. We assessed the levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in the thymus and spleen and estimated percentages of blood cells. Our results showed that LA induces oxidative damage by significantly elevating MDA and diminishing GSH levels, SOD, and CAT activities. LA administration led to a significant decline in blood parameters. However, co-administration with OG compensated oxidative stress by significantly reducing MDA, increasing GSH, SOD, and CAT. Oral administration of OG to rats attenuated anemia, thrombocytopenia, leucocytosis, eosinophilia, monocytosis, and neutropenia induced by LA. The present study indicates that LA induced Spleen, thymus, and blood toxicity, which was reversed by oral OG administration.

Sources of lead exposure in various countries

This review evaluates the sources of lead exposure worldwide. Studies from searches relating to sources of lead exposure in various countries within different regional zones were reviewed. Results indicated that in Nigeria, exposure sources include electronic waste, paint and batteries. In Mexico exposure sources include glazed ceramics, lead contaminated utensils and lead contaminated water, for India lead sources include cosmetics and traditional medicines. Sources of lead exposure in China include e-waste, traditional medicines and industrial emissions. In France, exposure sources included lead paint from older homes, imported ceramics and cosmetics and industrial emissions. Australia's exposure sources include paint, dust, imported toys and traditional medicines. Finally, in the United States exposure sources included paint, the industrial legacy of lead exposure and batteries. In high-income countries (HICs) the legacy of lead exposure keeps populations continuously exposed. In lower- and middle-income countries (LMICs), in addition to the legacy of lead exposure, lack of regulations or the inability to enforce regulations keeps populations exposed. In all, evidence suggests that lead exposure remains an issue of public health significance in both HIC and LMIC.

Determination of lead levels in maternal and umbilical cord blood at birth at the Lagos University Teaching Hospital, Lagos

BACKGROUND

Lead toxicity is a cause of intellectual disability in children and majority of affected children live in developing countries. Its adverse effect on pregnancy outcome has also been documented.

OBJECTIVES

To assess the relationship between maternal blood lead levels and umbilical cord blood lead levels in their corresponding newborn infants; to determine factors associated with high blood lead levels and the pregnancy outcome in participants.

MATERIALS AND METHODS

This was a cross-sectional descriptive study carried out at a tertiary Teaching Hospital, Lagos, Nigeria. Four hundred and forty pregnant women and their respective newborns delivered at the study centre. Blood samples were obtained from the mothers and umbilical cord of the newborns at delivery and analysed by atomic absorption spectrophotometry. Socio-demographic and obstetric data was obtained by questionnaires administered to the mothers. The anthropometric measurements of the babies were taken at birth and clinical data recorded. Main outcome measures were blood lead levels in mother and baby pair, socio-demographic factors, birth weight, gestational age, length, occipito-frontal circumference.

RESULTS

The median maternal and umbilical blood lead level was 64.3μg/dl and 39.2μg/dl respectively. The levels were above 5μg/dl in 75.6% and 66.8% of mothers and umbilical cord respectively. There was a strong positive correlation between the maternal and umbilical cord blood lead levels (rs = 0.80). Use of calcium supplements during pregnancy was significantly associated with a lower maternal blood lead level (p = 0.010) while recent painting and renovation of residential accommodation were associated with a higher umbilical cord blood lead level (p = 0.025). There were no statistically significant associations between the maternal and umbilical cord blood lead levels and the gestational age and anthropometry of the newborns at birth.

CONCLUSIONS

The blood lead levels in newborns of women residing in Lagos, Nigeria are high and administration of antenatal calcium is associated with lower blood lead levels.

The relationship of maternal bone density with nutritional rickets in Nigerian children

Factors that affect maternal bone mineral density may be related to the risk of nutritional rickets in their offspring. Our aim was to determine the relationship between maternal areal bone mineral density (aBMD) and rickets in Nigerian children. Using a case-control design, we measured forearm aBMD in 56 and 135 mothers of children with and without nutritional rickets, respectively. Active rickets was confirmed or excluded in all children radiographically. Using logistic regression, we assessed the association of maternal aBMD, adjusted for parity, pregnancy and lactation status, duration of most recent completed lactation, age of menarche, height, body mass index, and maternal age with nutritional rickets. The median (range) age of all mothers was 30years (17-47years), and parity was 4 (1-12). A total of 36 (19%) were pregnant and 55 (29%) were currently breast feeding. Mean (±SD) metaphyseal forearm aBMDs were 0.321±0.057 and 0.316±0.053g/cm² in mothers of children with and without rickets, respectively (P=0.60). Diaphyseal forearm aBMDs were 0.719±0.071 and 0.715±0.072g/cm², respectively (P=0.69). In an adjusted analysis, maternal forearm aBMD, bone mineral content and bone area at metaphyseal and diaphyseal sites were not associated with rickets in the child. In the adjusted analysis, rickets was associated with shorter duration of most recently completed lactation (aOR 0.91 for each additional month; 95% CI 0.83-0.99), older maternal age (aOR 1.07 for each additional year; 1.00-1.14), and less frequent maternal use of lead-containing eye cosmetics (aOR 0.20; 95% CI 0.05-0.64), without any difference in maternal blood lead levels. Maternal age, parity, age of menarche, height, and body mass index were not associated with having had a child with rickets in multivariate analysis. Nutritional rickets in Nigerian children was not associated with maternal forearm aBMD. Other unidentified maternal characteristics and practices likely contribute to the risk of rickets in Nigerian children.

Examination of Lead and Cadmium in Water-based Paints Marketed in Nigeria

BACKGROUND

In spite of the availability of substitutes for lead and cadmium compounds in paints, manufacturers continue to produce paints with high levels of these metals. As the population continues to grow and there is a continued shift from oil-based to water-based paints, the sales and use of these paints will increase the exposure of humans and the environment to these metals.

OBJECTIVES

We measured the levels of lead (Pb) and cadmium (Cd) in 174 paint samples marketed in Lagos and Ibadan, Nigeria. Paint samples from different manufacturers registered with and without Standards Organization of Nigeria (SON) were considered.

METHODS

Samples were acid digested using a microwave digester and the levels of the elements were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES).

DISCUSSION

The levels of Cd and Pb (dry weight) in all samples ranged from 98-1999 μg/g and 170-3231 μg/g, respectively. All the samples were above the permissible limits of 90 ppm of the US Consumer Product Safety Commission and 100 ppm limit of the European Union (EU) for Pb and Cd in paint.

CONCLUSIONS

We concluded that water-based paints marketed in Nigeria still contain substantial amounts of lead and cadmium which are detrimental to human health and the entire ecosystem. These metals are among the EU priority metals due to the increased risk of occupational exposure to humans and vulnerable groups such as children.

Prevalence and Risk Factors of Elevated Blood Lead in Children in Gold Ore Processing Communities, Zamfara, Nigeria, 2012

BACKGROUND

In March 2010, Medecins Sans Frontieres/Doctors Without Borders detected an outbreak of acute lead poisoning in Zamfara State, northwestern Nigeria, linked to low-technology gold ore processing. The outbreak killed more than 400 children ≤5 years of age in the first half of 2010 and has left more than 2,000 children with permanent disabilities.

OBJECTIVES

The aims of this study were to estimate the statewide prevalence of children ≤5 years old with elevated blood lead levels (BLLs) in gold ore processing and non-ore-processing communities, and to identify factors associated with elevated blood lead levels in children.

METHODS

A representative, population-based study of ore processing and non-ore-processing villages was conducted throughout Zamfara in 2012. Blood samples from children, outdoor soil samples, indoor dust samples, and survey data on ore processing activities and other lead sources were collected from 383 children ≤5 years old in 383 family compounds across 56 villages.

RESULTS

17.2% of compounds reported that at least one member had processed ore in the preceding 12 months (95% confidence intervals (CI): 9.7, 24.7). The prevalence of BLLs ≥10 µg/dL in children ≤5 years old was 38.2% (95% CI: 26.5, 51.4) in compounds with members who processed ore and 22.3% (95% CI: 17.8, 27.7) in compounds where no one processed ore. Ore processing activities were associated with higher lead concentrations in soil, dust, and blood samples. Other factors associated with elevated BLL were a child's age and sex, breastfeeding, drinking water from a piped tap, and exposure to eye cosmetics.

CONCLUSIONS

Childhood lead poisoning is widespread in Zamfara State in both ore processing and non-ore-processing settings, although it is more prevalent in ore processing areas. Although most children's BLLs were below the recommended level for chelation therapy, environmental remediation and use of safer ore processing practices are needed to prevent further exposures.

PATIENT CONSENT

Obtained.

ETHICS APPROVAL

The study protocol was approved by the US Centers for Disease Control Institutional Review Board-A and the National Health Research Ethics Committee of Nigeria.

COMPETING INTERESTS

The authors declare no competing financial interests.

Elevated Blood Lead Levels Are Associated with Reduced Risk of Malaria in Beninese Infants

INTRODUCTION

Elevated blood lead levels (BLL) and malaria carry an important burden of disease in West Africa. Both diseases might cause anemia and they might entail long-term consequences for the development and the health status of the child. Albeit the significant impact of malaria on lead levels described in Nigeria, no evaluation of the effect of elevated BLL on malaria risk has been investigated so far.

MATERIALS AND METHODS

Between 2010 and 2012, blood lead levels of 203 Beninese infants from Allada, a semi-rural area 50km North from Cotonou, were assessed at 12 months of age. To assess lead levels, blood samples were analyzed by mass spectrometry. In parallel, clinical, microbiological and hematological data were collected. More precisely, hemoglobin, serum ferritin, CRP, vitamin B12, folate levels, and Plasmodium falciparum parasitemia were assessed and stool samples were also analyzed.

RESULTS

At 12 months, the mean BLL of infants was 7.41 μg/dL (CI: 65.2; 83), and 128 infants (63%) had elevated blood lead levels, defined by the CDC as BLL>5 μg/dL. Lead poisoning, defined as BLL>10 μg/dL, was found in 39 infants (19%). Twenty-five infants (12.5%) had a positive blood smear at 12 months and 144 infants were anemic (71%, hemoglobin<110 g/L). Elevated blood lead levels were significantly associated with reduced risk of a positive blood smear (AOR = 0.38, P-value = 0.048) and P. falciparum parasite density (beta-estimate = -1.42, P-value = 0.03) in logistic and negative binomial regression multivariate models, respectively, adjusted on clinical and environmental indicators.

CONCLUSION

Our study shows for the first time that BLL are negatively associated with malarial risk considering other risk factors. Malaria is one of the main causes of morbidity and mortality in infants under 5 years worldwide, and lead poisoning is the 6th most important contributor to the global burden of diseases measured in disability adjusted life years (DALYs) according to the Institute of Health Metrics. In conclusion, due to the high prevalence of elevated BLL, health interventions should look forward to minimize the exposure to lead to better protect the population in West Africa.

Blood lead levels in children attending a tertiary teaching hospital in Enugu, south-eastern Nigeria

BACKGROUND

Reports have demonstrated widespread lead contamination of the Enugu environment and the possibility of childhood lead poisoning.

OBJECTIVE

To determine the blood lead levels of children attending University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu, Enugu State.

METHOD

Blood samples from 100 children were analysed for blood lead concentration using an atomic absorption spectrometer.

RESULTS

The mean (SD) age was 6·2 (2·13) years (range 1-15) and the mean (SD) blood lead level was 8·7 (5·4) μg/dl (range 0·3-17·7). Thirty-three per cent of the children had blood lead levels >10 μg/dl, which is the United States Center for Disease Prevention and Control action limit, and 36% of the children had blood lead levels of 5-10 μg/dl. Mean (SD) blood lead level in the 6-10-years age group was 11·3 (5·7) μg/dl and 9·4 (4·6) μg/dl in the >10-years age group, which is significantly higher than in the 1-5-years age group [7·5 (5·1) μg/dl, P = 0·03]. Males had significantly higher mean (SD) blood lead levels than females [9·6 (5·8) vs 6·8 (3·8), P = 0·03].

CONCLUSION

One-third of children had blood lead levels >10 μg/dl, particularly older and male children. Blood lead screening should be considered for sick children, and further screening of blood lead levels in children should be undertaken in Enugu and other parts of Nigeria, and efforts made to identify the sources of exposure.

Zebrafish as a model for investigating developmental lead (Pb) neurotoxicity as a risk factor in adult neurodegenerative disease: a mini-review

Lead (Pb) exposure has long been recognized to cause neurological alterations in both adults and children. While most of the studies in adults are related to higher dose exposure, epidemiological studies indicate cognitive decline and neurobehavioral alterations in children associated with lower dose environmental Pb exposure (a blood Pb level of 10μg/dL and below). Recent animal studies also now report that an early-life Pb exposure results in pathological hallmarks of Alzheimer's disease later in life. While previous studies evaluating higher Pb exposures in adult animal models and higher occupational Pb exposures in humans have suggested a link between higher dose Pb exposure during adulthood and neurodegenerative disease, these newer studies now indicate a link between an early-life Pb exposure and adult neurodegenerative disease. These studies are supporting the "fetal/developmental origin of adult disease" hypothesis and present a new challenge in our understanding of Pb neurotoxicity. There is a need to expand research in this area and additional model systems are needed. The zebrafish presents as a complementary vertebrate model system with numerous strengths including high genetic homology. Several zebrafish genes orthologous to human genes associated with neurodegenerative diseases including Alzheimer's and Parkinson's diseases are identified and this model is starting to be applied in neurodegenerative disease research. Moreover, the zebrafish is being used in developmental Pb neurotoxicity studies to define genetic mechanisms of toxicity and associated neurobehavioral alterations. While these studies are in their infancy, the genetic and functional conservation of genes associated with neurodegenerative diseases and application in developmental Pb neurotoxicity studies supports the potential for this in vivo model to further investigate the link between developmental Pb exposure and adult neurodegenerative disease pathogenesis. In this review, the major factors influencing the pathogenesis of neurodegenerative diseases, Pb neurotoxicity, the developmental origin of adult disease paradigm, and the zebrafish as a model system to investigate the developmental origin of low-dose Pb-induced neurodegenerative diseases is discussed.

Toxic and essential elements in children's blood (<6 years) from Kinshasa, DRC (the Democratic Republic of Congo)

In this study we determined the concentration of 9 trace elements (As, Cd, Cu, Hg, Mn, Mo, Pb, Se and Zn) in whole blood of children (n=100, 64 girls, 36 boys and median age: 36 months) using inductively coupled plasma mass spectrometry (ICP-MS). The proportion of children potentially deficient in essential elements or poisoned by toxic elements was evaluated. The aging effects on the concentration of these elements were also investigated. The median values were 3.17μg/L (As), 0.15μg/L (Cd), 1.1mg/L (Cu), 2.1μg/L (Hg), 10.4μg/L (Mn), 17.7μg/L (Mo), 8.7μg/dL (Pb), 10.7μg/L (Se) and 5.0mg/L (Zn). The concentration of many elements (As, Cd, Hg, Mn, Pb and Zn) showed significant age variations but not sex influence. Regarding levels of the essential elements (Cu, Mn, Mo, Se and Zn), B-Cu, B-Mn, B-Se and B-Zn were in the normal range, whereas exceeded levels were observed for B-Mo. None of these children was deficient in essential elements. Except B-Cd, all toxic elements showed exceeded blood levels. The proportion of children potentially poisoned by toxic elements varies from 10% (n=10) to 95% (n=95) and depends on toxic element: 95% for As, 10% for Hg and 35% for Pb. The main health concerns emerging from this study are the high As, Hg and Pb exposures of the Kinshasan children requiring further documentation, corrective actions and the implementation of appropriate regulations.

Blood lead concentrations in sub-Saharan African children below 6 years: systematic review

OBJECTIVE

To assess the geometric mean of blood lead levels in children aged below 6 years living in sub-Saharan Africa.

METHODS

Search strategies were developed in MEDLINE, Web of Science and Google scholar system, supplemented by screening of references from included papers and review articles. Studies including children younger than 6 years residing in sub-Saharan Africa (SSA) were eligible. The studies were assessed for quality of methods for blood collection, for participants' recruitment and for quality control for lead analyses. Data were extracted and synthetised by estimating the mean weighted by sample size.

RESULTS

A total of 11 148 published papers were identified with only 16 studies conducted in SSA. Only nine of them were relevant of inclusion criteria. The weighted mean of blood lead levels was 13.1 μg/dl. Five of included studies were classified as being less likely to present selection bias, having performed venipuncture and adequate quality control for lead analyses. The weighted mean from analyses involving only these studies was 16.2 μg/dl. Six of the included studies reported the prevalence of blood lead levels ≥10 μg/dl; levels ranged from 7.0% to 70.9%. Only one study reported the prevalence of blood lead levels ≥5 μg/dl (50%).

CONCLUSIONS

The geometric mean of blood lead levels in sub-Saharan African children is still elevated relative to the US children. The new standard from the Centers for Disease Control and Prevention (5 μg/dl) implies that important efforts should be directed towards the initiation (or reinforcement) of prevention programmes and thorough research studies in sub-Saharan Africa.

Elevated blood lead levels and sources of exposure in the population of Kinshasa, the capital of the Democratic Republic of Congo

The objective of this study was to determine blood lead levels (BLLs) and the possible sources of exposure in the population of Kinshasa, the capital of the Democratic Republic of Congo. A cross-sectional survey was carried out from January to May 2008 in a representative sample of the Kinshasan population. BLL was measured in 275 individuals (53.4% women) aged 1-70 years in the urban area of Kinshasa and from 60 additional subjects in the rural area. Pb was also determined in environmental specimens (air and soil, indoor and outdoor). BLL in the study population ranged from 2.9 to 49.3 μg/dl (median, 9.9 μg/dl). The median BLL among children aged <6 years was 11.5 μg/dl (range: 3.0-37.8 μg/dl). Of these children, 71% had elevated BLL (≥10 μg/dl) and 22% had BLL ≥20 μg/dl. The proportion of elevated BLL (≥10 μg/dl) was higher for children aged <3 years than for children aged 3 to 5 years (97% vs 56%). A higher prevalence of elevated BLL was observed in urban compared with rural children (71% vs 20%). Significantly higher BLLs were also found in children whose mother consumed fired clay during pregnancy. Residential informal activities in the recycling of car batteries also contributed to elevated BLL in children. The elevated background of Pb exposure in the Kinshasan population indicates a public health issue that requires corrective actions. Pb-contaminated dust and air in children's home is an issue of public health concern. The use of leaded gasoline and the activities of car battery recycling in certain residences appear to constitute the main sources of exposure in the city of Kinshasa. The traditional use of fired clay for the treatment of gastritis by pregnant women is another significant contributor for elevated BLL in children.

The effect of calcium supplementation on blood lead levels in Nigerian children

OBJECTIVE

To determine whether calcium supplementation alters the risk of lead toxicity.

STUDY DESIGN

Children aged 12-18 months from 3 communities in Nigeria were assigned to receive daily calcium supplementation, as either calcium carbonate (400 mg) or ground dried fish (529 ± 109 mg), or placebo. All children received 2500 IU of vitamin A. Levels of blood lead, calcium, and vitamin D metabolites were measured at baseline and after 12-18 months (n = 358).

RESULTS

The mean (± SD) baseline lead level was 11.1 ± 7.8 μg/dL (range, 1-43 μg/dL; median, 9 μg/dL); 44.7% of subjects had a lead level >10 μg/dL. After 12-18 months, the mean lead level was 8.1 ± 6.3 μg/dL (range, 1-48 μg/dL; median, 6 μg/dL), with 22.6% with a level >10 μg/dL. Lead levels at baseline varied among communities (P = .01) and were higher in children who used eye cosmetics or lived near a lead-acid battery melter (both P < .001). In a multiple regression model, the decrease in blood lead level was predicted by age, baseline lead level, and time of final lead value at 12-18 months (R(2) = 31%), but not by calcium supplementation (P = .98).

CONCLUSIONS

Lead toxicity is common in Nigerian children, but calcium supplementation does not affect blood lead levels.

Africa's growing cancer burden: environmental and occupational contributions

BACKGROUND

Primary prevention measures are needed for Africa's cancer burden (715,000 new cases and 542,000 deaths in 2008), a burden projected to double by 2030 due to demographic changes alone. Control of cancer-causing infections and lifestyle-related carcinogens will play a significant role in prevention, but less often addressed are environmental and occupational contributions.

METHODS

We review environmental issues that contribute to Africa's Cancer burden.

RESULTS

We demonstrate evidence of the impact of environmental carcinogens on the cancer burden as of now and that circumstances present today may increase their contribution further. Suboptimal implementation and monitoring of environmental protection and of occupational health standards, including in the informal sector, use of outdated technologies in industry and lack of awareness of potential hazards in the specific employment structure give rise to high levels of exposures. Carcinogens of concern include (i) those that have been long present (e.g. indoor air pollution) whose contribution may increase as life-expectancy increases and long latency periods for cancer are realised, (ii) exposures in mining and agricultural sectors and (iii) modern environmental hazards, including urban air pollution and agents arising from the mis-management of hazardous waste from local, industrial and trans-boundary sources.

CONCLUSIONS

Actions taken to reduce exposures and research to fill gaps in knowledge, adapted to local settings, could help mitigate the cancer burden.

In vivo distribution of lead in male and female rats after intraperitoneal and oral administration

The resultant effects of lead exposure are seen in almost all the systems of the body and results in toxicity to many organs. Since toxicity depends on its degree of uptake, distribution and metabolism, the authors investigated the differential uptake, accumulation and distribution of lead in organs of males and female Wistar rats following various routes of administration. Group 1 served as control male and control female; group 2 males and females received 5 mg/kg body weight of lead intraperitoneally for 8 days while group 3 males and female rats were administered drinking water containing 100 ppm of lead acetate for 18 days. Tissues were collected for analysis of the lead content using atomic absorption spectroscopy. The relative retention of lead by the tissues was greater in rats exposed to lead by the i.p. route varying in the order of accumulation / uptake in males as lungs > spleen > stomach > kidney > blood > heart and in females as spleen > stomach > heart > kidney > blood > lungs (i.p. route) and (oral route) as for males kidney > lungs > stomach > blood > heart > spleen, and females as kidney > lungs > stomach > blood > heart > spleen. Male Wistar rats showed more accumulation with oral exposure in lungs, spleen and blood with values for kidney and stomach being significantly ( p < 0.05) higher when compared with females. Female Wistar rats showed more accumulation with i.p. exposure for spleen and stomach tissues while values for the heart was significantly ( p < 0.05) higher than the males. Our findings suggest that lead retention and the organ distribution varied depending upon the sex and route of lead administration.

Assessment of blood and urine lead levels of some pregnant women residing in Lagos, Nigeria

Assessment of lead in blood (BLL) and lead in urine (ULL) of some non-occupationally exposed, nonsmoking 214 pregnant Nigerian women, aged 17 to 49 years, and resident in Lagos was carried out using atomic absorption spectrometry with control subjects consisting of 113 nonpregnant women. From results, the mean BLL and ULL (μg/dL) for pregnant women (59.5±2.1; 29.4±1.1) were significantly (p<0.01) higher than the values obtained for nonpregnant women (27.7±1.1; 9.2±0.6). BLL found in women in the first, second, and third trimesters were 57.2±2.3, 61.6±2.2, and 63.1±1.8, respectively. ULL could not serve to predict BLL due to weak correlations (r=-0.06 to +0.15; p>0.10). Study is a contribution to blood and urine lead status of Nigerian pregnant women, being relevant for healthcare management purposes, public health decision making, and possible primary prevention activities.

Assessment of environmental distribution of lead in some municipalities of South-Eastern Nigeria

Lead (Pb) levels were measured in roadside surface soils, dust particles and rain water samples from the urban cities of Enugu, Awka, Onitsha, Nnewi, Aba, Port Harcourt and Warri in Southern Nigeria in 2007 and 2008. Samples were collected during the dry season, while rain water samples were collected during the early rain (April–June), mid rain (July–August) and late rain seasons (September–October) for the two years. Soil samples were collected from traffic congested roads, dust was collected by tying a plastic basin on a pole 1.5 m above ground level and leaving it for 45 days. Rain samples were collected from three equidistant points. Samples were analyzed by AAS. The highest soil Pb of 120.00 ± 0.00 and 80.36 ± 0.00 mg/kg were reported in Onitsha for 2007 and 2008, respectively. Nnewi showed 33.40 ± 0.01 and 4,238.29 ± 0.00 mg/kg for 2007 and 2008. Aba had 22.56 ± 0.01 and 21.28 ± 0.00 mg/kg for 2007 and 2008. Higher concentrations were recorded for Nnewi and Port Harcourt in 2008 than in 2007. Enugu had more in 2007 while Awka had more in 2008. Dust Pb ranged from 0.13–0.49 mg/kg and 0.15–0.47 mg/kg for 2007 and 2008, respectively. Rain samples had the least Pb concentration, ranging from 0.103 ± 0.000 to 0.163 ± 0.046 mg/L. We may conclude that Nigerians are exposed to environmental Pb.

Prenatal and adolescent blood lead levels in South Africa: child, maternal and household risk factors in the Birth to Twenty cohort

INTRODUCTION

The risk factors for lead exposure in developing countries have not been fully described. This study looks at child, maternal and household factors associated with increased risk of lead exposure at birth and at 13 years of age in the Birth to Twenty cohort.

METHODS

Mothers were recruited from antenatal clinics in the Johannesburg-Soweto metropolitan area in 1990 (n=3273). Lead levels were analysed in cord blood collected at birth (n=618) and at 13 years (n=1546). Data on selected child, maternal and household factors were collected using a structured questionnaire in the third trimester and at 13 years of age. Statistical analyses were conducted to determine the associated risk factors.

RESULTS

The mean blood lead level at birth was 5.85 microg/dl, and at 13 years of age it was 5.66 microg/dl. The majority of children had blood lead levels above 5 microg/dl (52% at birth and 56% at 13 years). At birth, being a teenage mother and having low educational status were strong predictors for elevated cord blood lead levels. Being a male child, having an elevated cord blood level, and lack of household ownership of a phone were significant risk factors for high blood lead levels at 13 years.

CONCLUSION

Significant associations found in the study point to the low socio-economic status of lead-affected mothers and children. These poor circumstances frequently persist into later childhood, resulting in continued high lead levels. Thus broader measures of poverty alleviation and provision of better education may help decrease the risk of exposure.

Lead and cadmium levels of commonly administered pediatric syrups in Nigeria: a public health concern?

Fifty different pediatric syrups were randomly sampled from patent medicine stores and pharmaceutical shops within Awka, in Anambra State between November 2007 and May 2008. Syrups were ashed before digestion using conc. aqua regia, HCl:HNO(3) (3:1) and lead and cadmium were assayed with AAS 205A. Results revealed that 60 and 98% of the sample size had lead and cadmium respectively. The lead levels ranged from 0.01 in chloroquine to 1.08 mg/l in magcid suspension. The highest level of cadmium was seen in magcid suspension with concentration of 2.45 mg/l while lowest concentration of 0.01 in emzolyn and colipan. About 41.2% of the locally made syrup had none detectable levels of lead while all the syrup had detectable levels of cadmium. Lead levels ranged from 0.01 mg/l in cadiphen manufactured in Dholka, India to 0.09 in maxiquine made in England. About 68.8% of the imported syrups of the imported syrups had non detectable levels of lead. Chloramphenicol and zentel albendazole syrups had 0.60 and 0.88 mg/l of cadmium respectively. Bellis cough syrup showed the lowest level (0.01 mg/l) of cadmium. Only erythromycin suspension representing 6.3% had non detectable level of cadmium of the imported syrups. Due to the Cd and Pb levels found, we suggest that the behaviour scenario (here, self administration without medical assistance) should be properly taken under control. Along with this, contamination sources or vulnerable practices during syrups preparation should be also assessed in a tiered approach, towards the minimization of noxious presence in syrups and the promotion of quality of Nigerian-made products.

Maternal nutritional status during pregnancy and surma use determine cord lead levels in Karachi, Pakistan

OBJECTIVES

To estimate the umbilical cord blood lead levels (BLLs) of Pakistani neonates and to identify determinants for umbilical BLLs.

METHODS

We conducted a cross-sectional study of mothers and infants at one of the two obstetric units of two tertiary care hospitals in Karachi during January-August 2005. Information from 540 mothers selected randomly from those registered for delivery was obtained about their pregnancy, diet, and current and past lead exposures. We collected umbilical cord blood for lead levels analyzed using graphite furnace atomic absorption spectrophotometry. We computed geometric and arithmetic means. We performed multiple linear regression analysis to identify factors associated with log-transformed umbilical cord BLLs. We also performed logistic regression analysis to identify determinants of high lead cord BLLs (10 microg/dl).

RESULTS

The geometric mean cord BLL of the neonates was 9.6 microg/dl; arithmetic mean (S.D.) was 10.8 microg/dl (5.7) with a median of 9.7 microg/dl and a range of 1.8-48.9 microg/dl. Women who reported intake of less than 58.5mg of elemental iron supplement per day during pregnancy had cord BLL of 10.0 microg/dl; in comparison those women who had higher iron intake had lower cord BLL (8.4 microg/dl). Those who used surma (an eye cosmetic) daily had higher cord BLL (11.5 microg/dl) as compared to those who used it less frequently (9.4 microg/dl). In multivariable linear regression model, higher iron intake, owning a car, and being in 2nd quartile of mid-arm circumference were associated with low lead levels while father's occupation in lead-based industry was associated with significantly higher umbilical cord BLLs. There was interaction of daily surma use and ethnicity. Geometric mean BLLs were varied among surma users by ethnicity.

CONCLUSIONS

Umbilical cord BLLs are high in Karachi, Pakistan, in comparison to those in developed countries such as United States. Measures are needed to reduce fetal lead exposure to prevent adverse affect on neurocognitive development. Association of low iron (below RDA of 60 mg per day) with high umbilical cord has implications for strengthening iron supplement intake during pregnancy. Umbilical cord BLLs differed among surma users by ethnicity.

Lead levels in paint flakes from buildings in Nigeria: a preliminary study

Lead is a malleable metal previously used to improve the durability and color luster of paint applied in homes and on industrial structures such as bridges. Lead has deleterious effects on multiple organs in humans. There is paucity of information on the extent of the use of lead-based paint in Nigerian houses. This study has attempted to estimate the extent of use of lead-based paint in buildings in Eastern Nigeria using 168 buildings. Flaked paint samples were collected from residential, church, commercial, and school buildings from four most populous cities in Eastern Nigeria namely Enugu, Onitsha, Aba, and Port Harcourt, and they were digested using conc HNO3:HCLO4 (1:1) and analyzed using atomic absorption spectrophotometer. The lead levels from buildings in Enugu ranged from 39.385 ± 1.111–69.843 ± 4.886 mg/kg. The highest level of lead was found in Onitsha ranging from 49.503 ± 0.000–74.352 ± 0.571 mg/kg. Residential buildings, which mainly serve the under privileged populations, has the highest lead level in this study. In Aba, the highest lead level (66.432 ± 0.013 mg/kg) was found in commercial buildings aged 5–10 years. The lead levels in paint flakes from buildings in the four cities tended to decrease with increasing age of the buildings. Taken together all the building paint flakes from the four cities had lead levels higher than the United States Environmental Protection Agency permissible level of 5 mg/kg. There is a need for primary intervention strategy to reduce the paint lead levels in Nigeria.

Pediatric vitamin D and calcium nutrition in developing countries

Over one billion humans have insufficient circulating levels of vitamin D, and dietary insufficiency of calcium is common in developing countries. Worldwide, nutritional rickets is considered to be the most common non-communicable disease of children. Rickets can be due either to primary deficiencies of vitamin D or calcium or to combined deficiencies of both elements. Vitamin D deficiency is also increasingly linked to non-skeletal complications. Even without laboratory and radiologic resources, the diagnosis of rickets is considered clinically when a child presents with limb deformities and has beaded ribs and widened wrists and ankles. Prevention is possible through increased sun exposure and dietary enhancement. Treatment of nutritional rickets involves provision of adequate vitamin D and calcium. Further research is needed to elucidate the precise epidemiology of vitamin D and calcium deficiencies in developing countries, to determine the roles of additional pathologic factors contributing to the development and morbidity of rickets, to improve affordable and feasible means of diagnosing rickets in resource-limited areas, to better target at-risk populations for preventive interventions, to identify accurate dosing and delivery of therapeutic interventions, and to evaluate the long-term consequences of vitamin D and calcium deficiencies in childhood.

Lead poisoning associated with malaria in children of urban areas of Nigeria

The principal objectives of this study are to (a) investigate the prevalence of elevated blood lead levels (EBLLs) in children of three major cities of Nigeria with different levels of industrial pollution; (b) identify the environmental, social and behavioral risk factors for the EBLLs in the children; and (c) explore the association between malaria (endemic in the study areas) and EBLLs in the pediatric population. The study involved 653 children aged 2-9 years (average, 3.7 years). The mean blood lead level (BLL) for the children was 8.9+/-4.8microg/dL, the median value was 7.8microg/dL, and the range was 1-52microg/dL. About 25% of the children had BLL greater than 10microg/dL. There were important differences in BLLs across the three cities, with the average value in Ibadan (9.9+/-5.2microg/dL) and Nnewi (8.3+/-3.5microg/dL) being higher than that in Port Harcourt (4.7+/-2.2micro/dL). Significant positive associations were found between BLL and a child's town of residence (p<0.001), age of the child (p=0.004), length of time the child played outside (p<0.001), presence of pets in a child's home (p=0.023), but negatively with educational level of caregiver (p<0.001). This study is one of the first to find a significant negative association between BLL and malaria in a pediatric population, and this association remained significant after controlling for confounding diseases and symptoms. The shared environmental and socio-demographic risks factors for lead exposure and Plasmodium (most common malaria parasites) infection in urban areas of Nigeria are discussed along with possible ways that lead exposure may influence the host response to infection with malarial parasites.

Lead content of dried films of domestic paints currently sold in Nigeria

Children are at higher risk from lead exposure because their developing neural system is susceptible to its neurotoxic effects. We studied lead levels of paints manufactured in Nigeria in 2006. Lead levels in 5 colors of paints, each from different manufacturers were measured using flame-atomic absorption spectroscopy. We found that 96% of the paints had higher than recommended levels of lead. The mean lead level of paints ranged from 84.8 to 50,000 ppm, with mean of 14,500 ppm and median of 15,800 ppm. The main determinant of lead levels was color of the paint. As lead levels in paint sold in the past years in Nigeria are likely to be at least as high as that currently sold, it is likely that many existing houses contain dangerously high levels of lead. Efforts need to be undertaken to assess the presence of high lead levels in existing housing and if detected, intervention programs for eliminating risk of exposure should be developed in addition to measures to increase awareness and enforce regulations leading to the elimination of lead based domestic paint.