Current pediatric and maternal lead levels in blood and breast milk in Andean inhabitants of a lead-glazing enclave

Evaluating postnatal exposure to six heavy metals in a Chinese e-waste recycling area

This study is the first to assess postnatal exposure to heavy metals using breast milk in an electronic waste (e-waste) recycling area. From January to April 2021, 102 and 97 breastfeeding women were recruited from an e-waste recycling area and a control area, respectively. Four weeks after delivery, medical staff collected 20 mL of breast milk from each participant. The breast milk was tested for six heavy metals (lead, cadmium, chromium, arsenic, copper, and manganese) using inductively coupled plasma mass spectrometry (ICP-MS). The estimated daily intake (EDI) of infants during breastfeeding was calculated to assess the impact of postnatal exposure to heavy metals on infant health. The concentrations of chromium and lead in the breast milk were significantly higher in the e-waste recycling area than in the control area. Chromium concentrations in breast milk was 34.3%, exceeding the permissible limits set by the World Health Organization (WHO), in the e-waste recycling area, which is 16 times higher than that in the control areas. The EDIs of lead and chromium in the e-waste area were twice as those in the control area. This strongly indicates that the potential impact of postnatal exposure to lead and chromium on infant and child health in e-waste recycling areas cannot be ignored. Infants and children in e-waste recycling areas are at risk of long-term exposure to heavy metals. Therefore, ongoing health monitoring is necessary.

Concentrations and determinants of lead, mercury, cadmium, and arsenic in pooled donor breast milk in Spain

AIM

To measure concentrations of lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) in longitudinally collected donor breast milk samples and to determine associated factors.

METHODS

Pb, Hg, Cd, and As concentrations were measured in 242 pooled breast milk samples from 83 donors to a Human Milk Bank in Spain, in 2015-2018, determining their association with the donors' sociodemographic profile, dietary and lifestyle habits, and post-partum time, among other factors, and with the nutritional characteristics of samples. Mixed-effect linear regression was used to identify predictors of Hg and As concentrations in breast milk and mixed-effect logistic regression to identify predictors of the presence of Pb and Cd.

RESULTS

As was the element most frequently detected in milk samples (97.1%), followed by Hg (81.2%), Pb (50.6%), and Cd (38.0%). Their median breast milk concentrations were 1.49 μg/L, 0.26 μg/L, 0.14 μg/L, and <0.04 μg/L, respectively. Concentrations of As were higher in breast milk from primiparous donors, while Hg was higher in donors with a greater intake of fatty fish and meat and lower in samples collected after a longer post-partum time and with higher lactose content. Detection of Pb was higher among multiparous donors, those gaining weight since before pregnancy, and ex-smokers and was lower in samples collected more recently and from donors with greater intake of red meat and eggs. Cd detection was higher for donors with university education and those with greater intake of fried and canned food and more frequent use of hand cream and was lower for donors with greater bread intake.

CONCLUSIONS

These findings reveal relatively high As concentrations, moderate Hg concentrations, and low Pb and Cd concentrations in pooled donor breast milk. Several factors including post-partum time, parity, smoking habit, and the intake of certain food items were associated with the metal content of milk samples.

Elevated blood lead and metal/metalloid levels and environmental exposure sources in urban Ecuadorian school-age children and mothers

BACKGROUND

Lead and other toxic and potentially toxic metals and metalloids are significant contributors to the global burden of disease and disability. Studies characterizing blood metal/metalloid levels and potential sources of environmental exposures are limited for populations living in the major urban centers of Andean-area countries.

METHODS

We used ICP-MS to quantify blood levels of lead (PbB), cadmium (CdB), manganese (MnB), total arsenic (AsB), and total mercury (HgB) in school-age children (n = 47) and their reproductive-age mothers (n = 49) from low-resource households in Quito, Ecuador. These were compared to published 95th percentile reference values (RV95) and for PbB, also to CDC reference values. We used a detailed environmental questionnaire to examine the contribution of residential and neighborhood environmental exposure sources with participant blood metal/metalloid levels. We used ICP-MS to measure Pb levels in residential windowsill dust, floor dust, and drinking water samples and used XRF for paint samples.

RESULTS

Forty-five percent of the mothers had PbBs ≥ 5 μg/dL; 14.3% had PbBs ≥10 μg/dL. Maternal blood levels exceeded RV95s for PbB (76%), CdB (41%), MnB (88%), HgB (57%), and AsB (90%). Of children, 68% had PbBs ≥ 5 μg/dL, and 21.3% had PbB ≥10 μg/dL. Most child blood levels exceeded the RV95s for PbB (100%), CdB (100%), MnB (94%), and total HgB (94%) and AsB (98%). Most mothers (97%) and all children had blood levels indicating exposure to multiple metal/metalloid mixtures. Maternal and child PbBs were moderately correlated with each other but the other four metals/metalloids were not. Factors associated with maternal blood metal/metalloid levels were residence in a home with an earthen floor (PbB) or bare cement block walls (MnB), living near a dirt-paved or cobblestone street (PbB), <50 m from a heavily trafficked major roadway (PbB, HgB), living in the Los Chillos (PbB) or Cotocollao neighborhoods (PbB, HgB), or in areas where street vendors grilled food using charcoal (MnB). Factors associated with child blood metal/metalloid levels were residence in a dirt floor home (PbB, CdB, AsB), living near a dirt-paved or cobblestone street (PbB), living in the El Camal or Cotocollao neighborhoods (AsB), or in local neighborhoods where scrap metal smelters (MnB) and LPG gas depositories (PbB) were present.

CONCLUSIONS

The elevated blood levels of PbB, other metal/metalloids, and metal/metalloid mixtures identified mothers and children in this exploratory study is an urgent public health and clinical concern. The exposure patterns suggest that traffic-related exposures, especially the resuspension of legacy Pb in dust, as well as other anthropogenic and geogenic sources may be important environmental contributors to metal/metalloid exposures in urban Ecuadorian mothers and children. Future studies are needed to confirm these findings and explore other potential exposure sources. Biomonitoring is also needed in order to formulate effective intervention strategies to reduce population exposure to toxic levels of environmental metals/metalloids.

Neurodevelopment and exposure to neurotoxic metal(loid)s in environments polluted by mining, metal scrapping and smelters, and e-waste recycling in low and middle-income countries

This review covers a wide body of literature to gain an understanding of the impacts of informal activities related to metal extraction (primary mining and recycling) on early life exposure to neurotoxicants and on neurodevelopment. In primary mining, gold extraction with Hg amalgamation is the main environmental cause of Hg pollution in most artisanal small-scale gold mining (ASGM) activities around the world. Nevertheless, in Sub-Saharan Africa (SSA), Pb disrupted from gold-related ores, mining, and artisanal cookware production are an important neurotoxicant that seriously contaminates the affected population, with devastating effects on children. In e-waste recycling settings, the range of neurotoxic substances that contaminate mothers and children is wider than in primary mining environments. Thus, Hg and Pb are major pre- and postnatal neurotoxicants affecting children in the informal metal extraction activities and SSA countries show the highest record of human contamination and of neurotoxic effects on children. There are additional sources of neurotoxic contamination from mining and metal processing activities (cyanide tailing in South America and SSA) and/or co-exposure to Hg-containing products such as cosmetics (soaps and Hg-based skin lightning creams in Africa) and pediatric Thimerosal-containing vaccines (TCVs, that breaks down to ethyl-mercury) in current use in middle and low income countries. However, the action of these neurotoxicants (per se or in combination) on children needs more attention and research. Studies show a negative association between biomarkers of all environmental metal(loid)s (As, Cd, Hg, Mn, and Pb) studied and neurodevelopment in young children. Sadly, in many unregulated activities, child labor is widely employed, thus presenting an additional occupational exposure. Children living in polluted environments related to metal processing are disproportionately exposed to a wide range of co-occurring neurotoxic substances. The review showed compelling evidence from highly representative parts of the world (Africa, Asia, and Latin America) that the studied neurotoxic substances negatively affected areas of the brain associated with language, memory and executive function, as well as psychosocial behavior. Protecting the environment and children from unregulated and highly polluting metal extraction and processing are inextricably intertwined and deserve urgent attention.

Exposure to environmental neurotoxic substances and neurodevelopment in children from Latin America and the Caribbean

Environmental (and occupational) exposure to neurotoxic substances is a worldwide problem that can affect children's neurodevelopment (ND). In Latin American and Caribbean (LAC) countries there are over 300 million children living under the threat of neurodevelopmental delays due to toxic environmental exposure. Large industrial centers, intense mining and agricultural activities, along with changing complex ecosystems constitute a mosaic that drives contamination of air, water and the food chain. Neurotoxic contaminants such as pesticides (organochlorines, organophosphates, carbamates, pyrethroids, neonicotinoids, and manganese fungicides), chemicals of industrial use (phthalates), and metals (Hg, Pb, Al, As, F, Cd, Mo, Mn) are at the center of environmental exposure studies. Exposure to neurotoxic substances singly or in combination with other compounds or socioeconomic stressors (maternal education, socio-economic and nutritional status) intertwined with occupational and para-occupational exposure can affect ND (motor, cognition, behavior) of children. Significant negative effects of pesticides and neurotoxic elements on ND were found in all studied countries, affecting especially the less-privileged children from laboring families. Studies showed that exposures to the neurotoxicants in human milk are secondary to their more lasting effects during prenatal exposure. This review integrates exposure (prenatal and breastfeeding), metabolism, and ND effects of neurotoxicants. It highlights the overwhelming evidence showing that current levels of exposures are hazardous and detrimental to children's ND in LAC countries. The evidence indicates that a reduction in neurotoxicant exposure is essential to protect children's ND. Therefore, it is urgent to adopt policies and actions that prevent and remediate region-specific children's ND issues.

Probabilistic estimates of prenatal lead exposure at 195 toxic hotspots in low- and middle-income countries

BACKGROUND

Prior estimates of pediatric lead-related disease burden in low- and middle-income countries (LMICs) used population estimates of maternal blood lead levels (BLLs). This approach may underestimate fetal BLLs by not considering potentially high prenatal lead exposure from toxic hotspots. OBJECTIVES: We developed a probabilistic approach to using the Adult Lead Methodology (ALM) to estimate fetal BLLs from prenatal exposure to lead-contaminated soil at hotspots in the Toxic Site Identification Program (TSIP).

METHODS

We created distributions for each ALM parameter using published literature and extracted soil lead measurements from the TSIP database. Each iteration of the probabilistic ALM randomly selected values from the input distributions to generate a site-specific fetal BLL estimate. For each site, we ran 5000 model iterations, producing a site-specific fetal BLL distribution.

RESULTS

195 TSIP sites, in 33 LMICs, met our study inclusion criteria; an estimated 820,000 women of childbearing age are at risk for lead exposure at these sites. The predicted geometric means (GM) for site-specific fetal BLLs ranged from 3.3 μg/dL to 534 μg/dL, and 98% of sites had estimated GM fetal BLLs >5 μg/dL, the current reference level of the United States Centers for Disease Control and Prevention (CDC), while 11 sites had estimated GM fetal BLLs above the CDC chelation threshold of 45 μg/dL.

DISCUSSION

The TSIP soil lead data and this probabilistic approach to the ALM show that pregnant women living near TSIP sites may have BLLs that put their fetus at risk for neurologic damage and other sequelae, underscoring the need for interventions to reduce lead exposure at toxic hotspots.

Lead Exposure in Low and Middle-Income Countries: Perspectives and Lessons on Patterns, Injustices, Economics, and Politics

Lead exposure is a legacy issue that continues to affect vulnerable population groups globally, but particularly in low and middle-income countries (LMICS). We take a multi-disciplinary approach to examine the patterns of lead exposure in these countries, discuss the underlying injustices and socio-political causes, and the economic costs that are associated with exposure. We conclude with some lessons we drew from our discussion of lead across the disciplines and advocate for a number of approaches to solving this ongoing issue. These include (i) biomonitoring that could be integrated into existing health surveys or public health programs targeting young children; (ii) greater civic engagement to push for solutions; and, (iii) environmental control policies that represent a continuum of local, context-specific to broad, national-level, and even global approaches.

Arsenic, lead, mercury and cadmium: Toxicity, levels in breast milk and the risks for breastfed infants

Metals are ubiquitous in nature, being found in all environmental compartments, and have a variety of applications in human activities. Metals are transferred by maternal blood to the fetus via the placenta, and exposure continues throughout life. For the general population, exposure comes mainly from water and food consumption, including breast milk. In this paper, we reviewed studies on the toxicity of arsenic, lead, mercury and cadmium, the toxic metals of most concern to human health, focusing on the potential risks to newborns and infants. A total of 75 studies published since 2000 reporting the levels of these metals in breast milk were reviewed. Lead was the metal most investigated in breast milk (43 studies), and for which the highest levels were reported (up to 1515µg/L). Arsenic was the least investigated (18 studies), with higher levels reported for breast milk (up to 149µg/L) collected in regions with high arsenic concentrations in water (>10µg/L). Data from 34 studies on mercury showed that levels in breast milk were generally higher in populations with high fish consumption, where it may be present mainly as MeHg. Cadmium levels in breast milk were the lowest, with means <2µg/L in most of the 29 studies reviewed. Results of risk assessments indicated that the intake of arsenic, lead and mercury by infants through breastfeeding can be considered a health concern in most regions of the world. Although the potential risks to infants are mostly outweighed by the benefits of breast milk consumption, it is essential that contaminants be continuously monitored, especially in the most critical regions, and that measures be implemented by health authorities to reduce exposure of newborns and infants to these metals, and thus avoid unnecessary health risks.

Blood Lead Levels in Andean Infants and Young Children in Ecuador: An International Comparison

Lead (Pb) exposure in infants and children remains an international health concern. Blood lead (PbB) levels of a cohort of 130 Ecuadorian infants and young children aged 0.33 to 5.8 yr were compared to values reported for similar age groups in Africa, Asia, Europe, Latin America, and the United States. The mean PbB level for the total group of 130 Ecuadorian infants and young children in this study was 29.4 μg/dl (SD: 24.3; range: 3.0-128.2; median: 21.7; geometric mean: 20.7 μg/dl). The mean PbB level for the 0-2 yr age group (infants) was 33.6 μg/dl (SD: 28.9; median: 22.0; range: 3.9-119.7; geometric mean: 23.6 μg/dl), while the average PbB level for the 3-5 yr age group (young children) was 27.9 μg/dl (SD: 22.5: median: 22; range: 3-128.2; geometric mean: 19.8 μg/dl). The difference between the mean PbB levels for the infants and young children was not statistically significant. The average PbB level of 32.6 μg/dl for males was not statistically different from the mean PbB level of 26.3 μg/dl for females. The PbB levels observed in Ecuadorian infants and young children in this investigation were elevated above the World Health Organization (WHO) level of concern of 10 μg/dl and Centers for Disease Control and Prevention (CDC) current reference value of 5 μg/dl. Values were comparable to concentrations found in Pakistan, where occupational use of Pb is prevalent. These findings further indicate that infants and young children exposed to Pb from Pb glazing of ceramics in Andean Ecuadorian villages exhibit greater potential metal-mediated poisoning than children of similar ages in Asia, Europe, other Latin American countries, and the United States.

Lead levels in the breast milk of nursing andean mothers living in a lead-contaminated environment

Concentrations of lead (Pb) in breast milk (PbM) and blood (PbB) were measured in a current cohort of lactating mothers living in Andean communities where women of childbearing age engage in the occupational use of Pb, and compared to results obtained in earlier studies. Mean PbM concentration in the current group of breastfeeding mothers tested in 2012/2013 was 3.73 μg/L (SD: 7.3; range: 0.049-28.04), and significantly lower than the 9.83 μg/L (SD: 12.75; range: 0.2-49) previously observed in breastfeeding mothers in the study area from 1999 to 2007. Breastfeeding women in the current cohort showed an average PbM/PbB ratio of 3.6%, which is in agreement with other studies. The mean PbB level obtained for the current cohort was 7.8 μg/dl (SD: 5.2; range: 1.4-21), and significantly lower than the mean PbB level of 20.8 μg/dl (SD: 16.4; range: 4-73) obtained for the comparison group of breastfeeding mothers tested between 1999 and 2007. A correlation of .687 between paired PbM and maternal PbB was found, indicating that maternal PbB level is a significant predictor of PbM. Current PbM levels remain higher than international averages, but indicate that maternal Pb exposure has declined over time in the environmentally Pb-contaminated study area. The current reduction in Pb in milk and blood of breastfeeding mothers may be due to adherence to a Pb-exposure education and prevention program initiated by the authors in the study area years earlier, as well as recent improvements in local health care delivery.

Maternal blood, plasma, and breast milk lead: lactational transfer and contribution to infant exposure

BACKGROUND

Human milk is a potential source of lead exposure. Yet lactational transfer of lead from maternal blood into breast milk and its contribution to infant lead burden remains poorly understood.

OBJECTIVES

We explored the dose-response relationships between maternal blood, plasma, and breast milk to better understand lactational transfer of lead from blood and plasma into milk and, ultimately, to the breastfeeding infant.

METHODS

We measured lead in 81 maternal blood, plasma, and breast milk samples at 1 month postpartum and in 60 infant blood samples at 3 months of age. Milk-to-plasma (M/P) lead ratios were calculated. Multivariate linear, piecewise, and generalized additive models were used to examine dose-response relationships between blood, plasma, and milk lead levels.

RESULTS

Maternal lead levels (mean±SD) were as follows: blood: 7.7±4.0 μg/dL; plasma: 0.1±0.1 μg/L; milk: 0.8±0.7 μg/L. The average M/P lead ratio was 7.7 (range, 0.6-39.8) with 97% of the ratios being >1. The dose-response relationship between plasma lead and M/P ratio was nonlinear (empirical distribution function=6.5, p=0.0006) with the M/P ratio decreasing by 16.6 and 0.6 per 0.1 μg/L of plasma lead, respectively, below and above 0.1 μg/L plasma lead. Infant blood lead level (3.4±2.2 μg/dL) increased by 1.8 μg/dL per 1 μg/L milk lead (p<0.0001, R2=0.3).

CONCLUSIONS

The M/P ratio for lead in humans is substantially higher than previously reported, and transfer of lead from plasma to milk may be higher at lower levels of plasma lead. Breast milk is an important determinant of lead burden among breastfeeding infants.

Declining blood lead and zinc protoporphyrin levels in Ecuadorian Andean children

OBJECTIVES

To investigate current lead (Pb) exposure in children living in Andean Ecuadorian communities. Blood Pb (PbB) and zinc protoporphyrin (ZPP) levels were used respectively as biomarkers of acute and chronic Pb poisoning. The current PbB-ZPP levels were compared with previous pediatric PbB-ZPP levels recorded over years in the study area.

DESIGN AND METHODS

Samples of whole blood were collected from 22 Andean children of Quechua and Mestizo backgrounds and measured for PbB concentrations by graphite furnace atomic absorption spectroscopy. ZPP/heme ratio and ZPP whole blood (ZPP WB) levels were measured with a hematofluorometer.

RESULTS

The mean PbB level for children in the current study group was 14.5 μg/dL, which was significantly lower than the mean PbB level of 41.1 μg/dL found in the same study area in the 1996-2000 test period, and lower than the 22.2 μg/dL mean level found in the 2003-2007 period. The current mean ZPP/heme ratio was 102.1 μmol/mol, and the mean ZPP WB level was 46.3 μg/dL, both lower than values previously found in children in the study area.

CONCLUSION

While the current pediatric PbB-ZPP levels in the study area remain elevated in some children, the overall levels indicate a decline relative to levels observed in the same Pb-contaminated area in the period between 1996 and 2007. The elevated ZPP levels suggest a history of chronic Pb exposure, and potential iron deficiency in some children. The overall reduction in PbB-ZPP levels suggests a positive outcome of a Pb-exposure education and prevention program, and the therapeutic intervention of succimer chelation therapy.

Tracking blood lead and zinc protoporphyrin levels in Andean adults working in a lead contaminated environment

The purpose of this study was to investigate current blood lead (PbB) and zinc protoporphyrin (ZPP) levels in adults presently living in environmentally Pb-contaminated Andean communities, and to compare the findings with the PbB and ZPP levels of Pb-exposed adult cohorts from the same study area tested between 1996 and 2007. Blood samples from 39 adults were measured for PbB and ZPP concentrations. The current mean PbB level (22.7 μg/dl) was significantly lower than the mean (37.9 μg/dl) of the initial 1996 cohort. PbB levels for the 1997, 1998, 2003, and 2006 cohorts were also significantly lower than the levels for the 1996 group. Elevated ZPP/heme ratios of 103.3, 128.4, and 134.2 μmol/mol were not significantly different for the 2006, 2007, and 2012 groups, indicating chronic Pb exposure. While ZPP levels of Andean Ecuadorian Pb-glazing workers have remained elevated, PbB levels declined. Lead exposure of the workers needs to be continually monitored.

Lead poisoning in United States-bound refugee children: Thailand-Burma border, 2009

BACKGROUND

Elevated blood lead levels lead to permanent neurocognitive sequelae in children. Resettled refugee children in the United States are considered at high risk for elevated blood lead levels, but the prevalence of and risk factors for elevated blood lead levels before resettlement have not been described.

METHODS

Blood samples from children aged 6 months to 14 years from refugee camps in Thailand were tested for lead and hemoglobin. Sixty-seven children with elevated blood lead levels (venous ≥10 µg/dL) or undetectable (capillary <3.3 µg/dL) blood lead levels participated in a case-control study.

RESULTS

Of 642 children, 33 (5.1%) had elevated blood lead levels. Children aged <2 years had the highest prevalence (14.5%). Among children aged <2 years included in a case-control study, elevated blood lead levels risk factors included hemoglobin <10 g/dL, exposure to car batteries, and taking traditional medicines.

CONCLUSIONS

The prevalence of elevated blood lead levels among tested US-bound Burmese refugee children was higher than the current US prevalence, and was especially high among children <2 years old. Refugee children may arrive in the United States with elevated blood lead levels. A population-specific understanding of preexisting lead exposures can enhance postarrival lead-poisoning prevention efforts, based on Centers for Disease Control and Prevention recommendations for resettled refugee children, and can lead to remediation efforts overseas.

Heavy metal poisoning: management of intoxication and antidotes

Of the known elements, nearly 80% are either metals or metalloids. The highly reactive nature of most metals result in their forming complexes with other compounds such oxygen, sulfide and chloride. Although this reactivity is the primary means by which they are toxic, many metals, in trace amounts, are vital to normal physiological processes; examples include iron in oxygen transport, manganese and selenium in antioxidant defense and zinc in metabolism. With these essential metals toxicity occurs when concentrations are either too low or too high. For some metals there are no physiological concentrations that are beneficial; as such these metals only have the potential to cause toxicity. This chapter focuses on four of these: arsenic, mercury, lead and thallium.

Neurophysiologic and neurocognitive case profiles of Andean patients with chronic environmental lead poisoning

This report presents case profiles of three siblings in a family of lead (Pb) glazing workers living in a Pb-contaminated Andean village who presented with extreme plumbism (blood Pb levels: 47 to 128 microg/dl) from childhood to adolescence. These cases are examples of persons who have chronic Pb poisoning as a result of prolonged occupational and environmental exposure in a Pb-glazing ceramic cottage industry in the study area. Using behavioral and physiological techniques for measuring the integrity of the peripheral and central auditory systems, including otoacoustic emissions, and replicated auditory brainstem electrophysiological potentials, the authors found normal auditory neurosensory function in each patient, thus ruling out hearing impairment as a basis for adverse neurocognitive outcomes. This finding is contrary to the prevailing view regarding the detrimental effects of Pb poisoning on the cochlear and auditory brainstem of children. Performance on tests of visual spatial intelligence and auditory memory/attention was below average in these patients, which may underlie their reported learning disabilities. In two of the cases, there was an improvement in cognitive performance following a lowering of PbB levels from chelation therapy and Pb prevention education, suggesting some level of reversibility of their neurocognitive deficits. Nevertheless, these case profiles suggest that if the patients persist in Pb-glazing activities, in spite of repeated chelation therapy and family counseling, they may continue to be re-intoxicated and remain at risk for learning disabilities and other neurological impairments.

Neurocognitive screening of lead-exposed andean adolescents and young adults

This study was designed to assess the utility of two psychometric tests with putative minimal cultural bias for use in field screening of lead (Pb)-exposed Ecuadorian Andean workers. Specifically, the study evaluated the effectiveness in Pb-exposed adolescents and young adults of a nonverbal reasoning test standardized for younger children, and compared the findings with performance on a test of auditory memory. The Raven Coloured Progressive Matrices (RCPM) was used as a test of nonverbal intelligence, and the Digit Span subtest of the Wechsler IV intelligence scale was used to assess auditory memory/attention. The participants were 35 chronically Pb-exposed Pb-glazing workers, aged 12-21 yr. Blood lead (PbB) levels for the study group ranged from 3 to 86 microg/dl, with 65.7% of the group at and above 10 microg/dl. Zinc protoporphyrin heme ratios (ZPP/heme) ranged from 38 to 380 micromol/mol, with 57.1% of the participants showing abnormal ZPP/heme (>69 micromol/mol). ZPP/heme was significantly correlated with PbB levels, suggesting chronic Pb exposure. Performance on the RCPM was less than average on the U.S., British, and Puerto Rican norms, but average on the Peruvian norms. Significant inverse associations between PbB/ZPP concentrations and RCPM standard scores using the U.S., Puerto Rican, and Peruvian norms were observed, indicating decreasing RCPM test performance with increasing PbB and ZPP levels. RCPM scores were significantly correlated with performance on the Digit Span test for auditory memory. Mean Digit Span scale score was less than average, suggesting auditory memory/attention deficits. In conclusion, both the RCPM and Digit Span tests were found to be effective instruments for field screening of visual-spatial reasoning and auditory memory abilities, respectively, in Pb-exposed Andean adolescents and young adults.

Lead hazards for pregnant women and children: part 1: immigrants and the poor shoulder most of the burden of lead exposure in this country. Part 1 of a two-part article details how exposure happens, whom it affects, and the harm it can do

Poor, urban, and immigrant populations are at far greater risk for lead exposure than are other groups in the United States. Children with even slightly elevated blood lead levels are at increased risk for significant neurobehavioral problems that can extend through adolescence. Research has shown that elevated blood lead levels in pregnant women, even those well below 10 micrograms per deciliter-the Centers for Disease Control and Prevention's "level of concern"-can cause miscarriage, premature birth, low birth weight, and subsequent developmental delays in their children. Despite these well-established dangers, routine prenatal lead screening and lead education is not a standard of care. Part 1 of this two-part article presents a short case example of a pregnant mother with lead poisoning and describes the epidemiology of lead exposure in the United States, the main sources of lead exposure, and the effects of lead on the pregnant mother and the developing fetus and child. Prevention is crucial. Treatment options such as chelation must be used selectively and will not reverse damage once it's occurred. Part 2 will describe recommendations for screening, education, nutrition, reducing environmental exposures, and treatment.

Comparative analysis of zinc protoporphyrin and blood lead levels in lead-exposed Andean children

OBJECTIVES

The objective of this study was to investigate the zinc protoporphyrin/heme ratio (ZPP/heme) as a biomarker for chronic lead (Pb) poisoning in children with a history of high Pb exposure.

DESIGN AND METHODS

ZPP/heme ratio was measured in blood samples from 78 children (44 females and 34 males) with persistent Pb exposure from Pb glazing of ceramics in a local cottage industry in the Andes Mountains of Ecuador.

RESULTS

Mean blood lead (PbB) level was 26.4 microg/dL (SD: 23.2; range: 4.0-107.0), and the mean ZPP/heme ratio was 152.4 micromol/mol (SD: 190.6; range: 36.0-1064.0). A regression analysis of PbB level and ZPP/heme ratio revealed a significant association (r=0.761, p= <0.0001), with the logZPP showing a higher correlation with PbB (r=0.869, p= <0.0001). The ZZP/heme ratio decreased significantly with increasing age (ANOVA, p=0.030). The mean ZPP/heme ratios for females and males were 139.6 and 169.0 micromol/mol, respectively, and were not statistically different (t-test, p=0.504).

CONCLUSION

The elevated ZPP/heme ratios, coupled with high PbB levels observed in this cohort of Andean children of Pb-glazing workers, suggest chronic Pb intoxication and probable iron deficiency.

Lead Concentrations in Maternal Blood and Breast Milk and Pediatric Blood of Andean Villagers: 2006 Follow-up Investigation

OBJECTIVE

To determine the current lead (Pb) concentration in blood (PbB) and breast milk (PbM) of mothers and the PbB of children living in Andean Ecuadorian villages with high Pb contamination.

METHODS

Samples of whole blood from 93 participants (74 children and 19 adult women) were analyzed for Pb concentration by graphite furnace atomic absorption spectroscopy with Zeeman background correction, and milk samples from nursing mothers were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

Mean PbB concentration in children in 2006 was 26.7 microg/dL (SD: 23.0), and significantly lower than the mean PbB level in 1996 to 2000, but similar to the PbB level found in 2003. The mean PbB level of 22.0 microg/dL (SD: 20.6) for the 19 women in the 2006 study group did not differ significantly from the women in the 1996 to 2000 or 2003 study group. The PbM levels (range: 1-49 microg/L) of nursing mothers in the 2006 group were similar to the PbM values observed in the breast milk of nursing mothers in the same study area in 2003, and matched high PbB levels in some mother-infant pairs.

CONCLUSION

This study found elevated, but stable, PbB and PbM levels in mothers and elevated, but stable, PbB levels in children in 2006 that were consistent with the levels observed in 2003 in the same Andean villages.

Early (in uterus and infant) exposure to mercury and lead

Mercury and lead are toxic metals widely spread in the environment with bio-accumulative features that raises public health concerns. Both metals are equally dispersed in the human food chain but exposure and risk of toxicity during early human development are modulated by the diet and nutritional status. Understanding how Hg and Pb occur and interact with nutrients is fundamental to establish guidelines for diminishing exposure and the risk of toxicity. The risk of fetal and infant exposure to Hg can be influenced by maternal amalgam filling (inorganic Hg) and fish consumption (monomethyl Hg), whereas the risk of exposure to Pb is complex: maternal absorption depends on nutrient interactions (Ca and P); and maternal body Pb accumulation responds to all factors known to interact with bone and calcium metabolism. Maternal exposure to Hg and Pb is more important during fetal development than during breastfeeding. Moreover, these metals (especially Pb) are frequently higher in infant formulas which do not carry the nutritional and psychological advantages and protection of breastfeeding. Infant's reference dose is lower for Hg than for Pb, but risk of Pb contamination for fetuses and infant (breast- or formula-fed) is higher and lasts longer than Hg. Breastfeeding is essential to complete infant development. Interruption or suppression of breast-feeding with cow's milk-based formulas is not an option to environmental pollution.

Neurocognitive impairment in lead-exposed children of Andean lead-glazing workers

OBJECTIVE

The level of lead (Pb) exposure necessary to induce intellectual impairment has not been firmly established. Some studies using conventional language-based intelligence tests have reported that pediatric blood lead (PbB) levels lower than 10 microg/dL (0.483 micromol/L) are associated with neurocognitive impairment. However, these tests may introduce cultural biases in the assessment of intellectual functioning. The objective of this study was to assess the effects of PbB concentration on nonverbal intelligence in Andean children with chronic environmental Pb exposure using a nonlanguage-based test of cognitive functioning.

METHODS

Using Raven Colored Progressive Matrices (RCPM) as a measure of nonverbal intelligence, this study investigated the effects of Pb exposure (biomarker: PbB levels) on intellectual functioning in 188 chronically Pb-exposed children (age range: 5.33-11.67 years) of Ecuadorian Andean Pb-glazing workers.

RESULTS

The mean PbB level of the 188 children was 29.3 microg/dL (range: 3.5-94.3 microg/dL). Forty-seven children had PbB levels <10 microg/dL (Centers for Disease Control and Prevention [CDC] I classification), of which 30 had abnormal (ie, < or =25th percentile) RCPM standard scores. Of the 141 children with PbB levels > or =10 microg/dL, 97 had abnormal RCPM scores. A regression analysis revealed a statistically significant negative association (r = -0.331, P < 0.0001) between PbB level and RCPM standard score. Conversion of RCPM standard scores to estimated IQ scores showed an approximate two-point decrease in IQ for each 10-microg/dL increment in PbB level from 10 to >70 microg/dL.

CONCLUSIONS

Performance on a test of nonverbal intelligence was inversely associated with chronic Pb exposure in Andean children with PbB levels below and above the CDC risk management level of 10 microg/dL, with the decline in test scores suggesting a dose-response relationship.