Estimated burden of blood lead levels 5 microg/dl in 1999-2002 and declines from 1988 to 1994

Trends of Blood Lead Levels in US Pregnant Women: The National Health and Nutrition Examination Survey (2001–2018)

Objectives

This study investigates the trends of blood lead levels in US pregnant women based on the National Health and Nutrition Examination Survey from 2001 to 2018.

Methods

A total of 1,230 pregnant women were included in this study. The weighted logistic regression was applied to analyze the association between sociodemographic characteristics with high blood levels. We computed the blood lead levels for each survey period from 2001–2002 to 2017–2018. Moreover, we used the adjusted linear regression model to investigate the time-related change in blood lead level. The odds ratio (OR) with a 95% confidence interval (CI) was calculated accordingly.

Results

The mean blood lead was 0.73 ± 0.03 ug/dL, and high blood lead was observed in 2.53% of individuals. The Mexican Americans were more associated with high blood lead than the non-Hispanic white (OR, 1.072; 95% CI, 1.032-1.112). The mean blood lead level has decreased from 0.97 ug/dL in 2001–2002 to 0.46 ug/dL in 2013–2014. Afterward, a slight increase was observed with the mean blood lead of 0.55 ug/dL in 2015–2016 and 0.53 ug/dL in 2017-2018. In the adjusted linear regression model, each year's increase would lead to a 0.029 ug/dL decrease in blood lead (P < 0.001). However, no significant change was observed in the 2017–2018 cycle compared with 2009–2010 (P = 0.218).

Conclusion

This study summarized the trend of blood lead levels in US pregnant women over 2001–2018. Continued effort is still required to control lead sources better and protect this population from lead exposure.

Blood lead, nutrient intake, and renal function among type 2 diabetic patients

Lead (Pb) exposure has been reported to have nephrotoxicity. However, such an effect has not been well investigated in type 2 diabetes (T2D) patients, especially when taking into account the nutrition status of the patients. Therefore, we explore the association between blood lead levels (BLLs), dietary intake of nutrients, and impaired renal function among patients with T2D. We measured BLLs and biochemical parameters of renal injury in 780 patients. Dietary nutrients intake was assessed by a food frequency questionnaire in 420 of 780 participants. We found high BLLs were significantly associated with certain parameters of renal injury, and dietary intake of specific nutrients (mainly micronutrients) was associated with reduced BLLs at high percentile distribution of concentration. BLLs were also found to have moderation effects on the association between specific dietary nutrients and specific renal function parameters.

Comprehensive screen the lead and other toxic metals in total environment from a coal-gas industrial city (NW, China): Based on integrated source-specific risks and site-specific blood lead levels of 0-6 aged children

A new integrated source-specific risk model and site-specific blood lead levels (BLLs) of 0-6 children were introduced to comprehensive understand the status of the toxic metals in soil-dust-plant total environment from a Coal-Gas industrial city, NW China. 144 samples were collected and ten toxic metals (As, Ba, Co, Cr, Cu, Mn, Ni, Sr, Pb, and Zn) were screened by XRF and ICP-MS. It was found that the occurrences of toxic metals deferred in the different medium, such as Co, Cu, Pb, and Zn observed the trend of accumulating in soil and plant compared to clustered distributions of Cr, Mn and Ni preferred to accumulate in dust. However, few bioaccumulations observed in Ulmus pumila L. Toxic metals distributions in majority of sites influenced by coal combustion mixed sources and industrial activities posed the high integrated ecological risks and caused significant non-carcinogenic and carcinogenic integrated risks for local 0-6 children identified by new integrated source-specific risk model, especially observed in the priority contaminants Co and Pb. The site-specific BLLs confirmed that younger children fewer than 4 lived in the north region were more vulnerable to priority Pb pollution as their BLLs above 50 μg/L, almost up to 80 μg/L. Although proportions of source-specific risks to toxic metals changed in soil and dust, the critical sources from coal combustions and industrial activities posed the most important contribution to the local risks. Therefore, effective strategies targeting at critical sources on coal industries should be conducted to reduce risks, and mostly emphasize on the north hotspot areas.

Prenatal lead exposure: associations with growth and anthropometry in early childhood in a UK observational birth cohort study

Background: Lead is a neurotoxic metal that crosses the placenta freely. It has adverse effects on a range of birth outcomes. The few studies reporting on the associations of prenatal exposure to lead and child growth have had conflicting results. This study aimed to examine the effect of prenatal exposure to lead on children’s growth from 4 to 61 months of age. Methods: Pregnant women were enrolled in the UK Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood samples for pregnancies with a live birth were analysed for lead (n=4140). A 10% subsample of the offspring cohort (Children in Focus) were invited to clinics at 10 time points (4–61 months) at which anthropometric measurements were carried out; z-scores for height, weight and BMI were calculated using the 1990 British Growth Reference Standards. Associations between prenatal log10-lead concentrations and z-scores and other anthropometric measures were modelled using adjusted linear regression models in an imputed dataset for children who attended at least one clinic (n=574). Results: The median prenatal blood lead concentration was 3.60 (IQR 2.61–4.16) µg/dl. There was no evidence for any associations of prenatal lead exposure with z-scores for BMI, height or weight in adjusted models from age 4 to 61 months. There were no associations for other anthropometric measures including mid-upper arm circumference, head circumference and waist circumference. There was some evidence for a weakly positive effect of prenatal lead exposure on head circumference in girls at age 43 and 61 months (at 61 months unstandardised B coefficient 1.59 (95% CI 0.12, 3.16) cm, p=0.048) but not at other ages. Conclusions: There was no consistent evidence of associations between prenatal exposure to lead and measures of growth and anthropometry from age 4 to 61 months in this cohort of children in the UK.

Prenatal lead exposure: associations with growth and anthropometry in early childhood in a UK observational birth cohort study

Background: Lead is a neurotoxic metal that crosses the placenta freely. It has adverse effects on a range of birth outcomes. The few studies reporting on the associations of prenatal exposure to lead and child growth have had conflicting results. This study aimed to examine the effect of low-level prenatal exposure to lead on children’s growth from 4 to 61 months old. Methods: Pregnant women were enrolled in the UK Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood samples for pregnancies with a live birth were analysed for lead (n=4140). A 10% subsample of the offspring cohort (Children in Focus) were invited to clinics at 10 time points (4–61 months) at which anthropometric measurements were carried out; z-scores for height, weight and BMI were calculated using the 1990 British Growth Reference Standards. Associations between prenatal log10-lead concentrations and z-scores and other anthropometric measures were modelled using adjusted linear regression models in an imputed dataset for children who attended at least one clinic (n=574). Results: The mean prenatal blood lead concentration was 3.59±1.50 (range 1.22–14.70) µg/dl. There was no evidence for any associations of low-level prenatal lead exposure with z-scores for BMI, height or weight in adjusted models from age 4 to 61 months. There were no associations for other anthropometric measures including mid-upper arm circumference, head circumference and waist circumference. There was some evidence for a weakly positive effect of prenatal lead exposure on head circumference in girls at age 43 and 61 months (at 61 months unstandardised B coefficient 1.59 (95% CI 0.12, 3.16) cm, p=0.048) but not at other ages. Conclusions: There was no consistent evidence of associations between prenatal exposure to lead and measures of growth and anthropometry from age 4 to 61 months in this cohort of children in the UK.

Low-Level Cumulative Lead and Resistant Hypertension: A Prospective Study of Men Participating in the Veterans Affairs Normative Aging Study

Background

Bone lead offers a better method over blood lead measurement to discern long‐term lead exposure and accumulation. We examined the risk of resistant hypertension based on bone lead levels in a prospective cohort study of NAS (Normative Aging Study).

Methods and Results

Participants had clinic data on hypertension (systolic blood pressure, diastolic blood pressure, and antihypertension medication), lead (blood, bone‐patella, bone‐tibia), and demographic and confounding variables. Cases of resistant hypertension were identified by meeting criteria for: (1) inadequate systolic blood pressure (>140 mm Hg) or diastolic blood pressure (>90 mm Hg) while taking 3 medications or (2) requiring >4 medications for blood pressure control. A modified Poisson regression was used for model analysis. Of the 475 participants, 97 cases of resistant hypertension (20.4%) were identified. Among the cases of resistant hypertension, the median tibia and patella lead levels were 20 μg/g and 25 μg/g, respectively, while median tibia and patella lead levels were 20 μg/g and 27.5 μg/g, respectively, in participants without resistant hypertension. Tibia lead demonstrated a significant association with resistant hypertension (relative risk, 1.19; 95% confidence interval, 1.01–1.41 [P=0.04]) per interquartile range increase in tibia lead (13–28.5 μg/g). Patella lead was not associated with resistant hypertension (relative risk, 1.10; 95% confidence interval, 0.92–1.31 [P=0.31]) per interquartile range increase in patella lead (18–40 μg/g). Blood lead levels were not significantly associated with resistant hypertension (relative risk, 1.11; 95% confidence interval, 0.88–1.40 [P=0.38]).

Conclusions

Tibia lead represents a novel risk factor for resistant hypertension. Our study demonstrates an increased association between tibia lead and resistant hypertension status, with an increased risk of 19% per 1 interquartile range increase in tibia lead.

Dietary Patterns Are Not Consistently Associated with Variability in Blood Lead Concentrations in Pregnant British Women

BACKGROUND

During pregnancy lead crosses the placenta freely and can have adverse effects on the fetus, with the potential for lifelong impact on the child. Identification of dietary patterns and food groups in relation to measures of lead status could provide a more useful alternative to nutrient-specific advice to minimize fetal lead exposure.

OBJECTIVES

The aim of this study was to evaluate whether dietary patterns and food groups are associated with blood lead concentration (B-Pb) in pregnancy.

DESIGN

Whole blood samples were collected at a median of 11 wk gestation (IQR 9-13 wk) from women enrolled in the Avon Longitudinal Study of Parents and Children birth cohort study, and analyzed for lead. Dietary pattern scores were derived from principal components analysis of a food-frequency questionnaire (32 wk gestation). Associations of dietary pattern scores (quartiles), and of food groups (frequency of consumption), with the likelihood of B-Pb ≥5 µg/dL identified with adjusted logistic regression (n = 2167 complete cases).

RESULTS

There was a negative association between the "confectionery" dietary pattern and the likelihood of B-Pb ≥5 µg/dL (OR: 0.62; 95% CI: 0.41, 0.94) in an adjusted model. There were no associations with other dietary patterns. There was a positive association between the food group "all leafy green and green vegetables" and the likelihood of B-Pb ≥5 µg/dL (OR 1.45; 95% CI: 1.04, 2.01). Conversely, the food group "cakes and biscuits" was negatively associated (OR 0.63; 95% CI: 0.43, 0.93). After multiple imputation, there was a positive association of the "healthy" diet pattern and no association of the "confectionery" pattern.

CONCLUSIONS

We found limited evidence of an association between women's typical diet and B-Pb during pregnancy. Our findings do not indicate need to revise dietary guidance for pregnant women, who are advised to adopt a healthy diet in pregnancy, with a variety of foods consumed in moderation.

The association between lead and cadmium co-exposure and renal dysfunction

Both cadmium (Cd) and lead (Pb) exposure can induce kidney damage. However, the effects of combined exposure to Cd and Pb on renal function at environmental levels have not been fully clarified. In this study we investigated the renal function in a Chinese population co-exposed to Cd and Pb. A total of 331 subjects (215 women and 116 men), living in either a control or a polluted area, were included in this study. Cd and Pb in blood and urine (BCd, BPb, UCd, and UPb), and kidney effect markers including urinary N-acetyl-β-D-glucosaminidase (UNAG) and estimated glomerular filtration rate (eGFR), were determined, and the association between exposure markers and renal effect biomarkers were analyzed. The exposure levels in the polluted area were significantly higher than in the control area (all p < 0.01). The eGFR of subjects in the polluted area was decreased compared with that in the control area (p < 0.01). The subjects with high BCd/BPb (BCd ≥ 2 μg/L, BPb ≥ 100 μg/L) or high UCd/UPb (UCd ≥ 3 μg/g creatinine, UPb ≥ 10 μg/g creatinine) showed higher UNAG and UALB levels compared with other subgroups (p < 0.01). The probability of having elevated UNAG in subjects with high BCd/BPb was greater than those with low BCd/BPb [odds ratio (OR) = 2.6, 95% confidence interval (CI): 1.4-4.7), low BCd/high BPb (OR =3.1, 95% CI: 1.4-6.6), and high BCd/low BPb (OR = 1.7, 95% CI: 0.9-3.2). The OR of subjects with low UCd and high UPb, high UCd and low UPb, and high UCd/UPb were 2.9 (95% CI: 1.4-5.7), 3.3 (95% CI: 1.5-7.2), and 7.7 (95% CI: 4.0-14.7), respectively, compared with those with low UCd/UPb. The risk of decrease in eGFR was also higher in subjects with high UCd/UPb than for those with low UCd/UPb (OR = 7.2, 95% CI: 0.8-62.2). Our data demonstrate that Cd and Pb exposure, alone or in combination, are associated with renal impairment. In addition, co-exposure to Pb and Cd propagates the renal tubular dysfunction compared with Cd or Pb exposure alone.

Globally temporal transitions of blood lead levels of preschool children across countries of different categories of Human Development Index

In the past decades, efforts to eliminate lead from gasoline, paint and drinking water around the world have substantially reduced human blood lead levels. This study was therefore aimed at examining the global temporal trends in the blood lead levels of preschool children by the category of UN Human Development Index (HDI). In total, 103 blood lead records were retrieved from 51 articles searched from PubMed and Google Scholar, with study subjects aged up to 8years old. Collected preschool children blood lead levels were plotted chronologically by HDI category and their reciprocals were used in regression analysis against calendar year to establish their temporal transition trends in the past decades. Results show that the modes of blood lead level of the preschool children were reduced from 4-6μg/dL to 0.8-1.5μg/dL, from 6-15μg/dL to 3-6μg/dL and from 12-16 to 5-6μg/dL for the very high HDI countries, the high HDI countries and the medium/low HDI countries, respectively. The highest correlation coefficient, 0.849, between the reciprocal of blood lead level and the calendar year was found for the very high HDI countries. Based on the regression lines, the predicted preschool children mean blood lead levels in the year of 2030 are 0.74μg/dL, 2.21μg/dL and 2.86μg/dL, respectively, for the very high HDI countries, the high HDI countries and the medium/low HDI countries. Persistent differences in blood lead level prevailed among countries of different HDI category, suggesting the effects of disparities and inequalities, at the state level, on preschool children blood lead levels. Further action is warranted to reduce the already low environmental lead exposure to eliminate the developmental burden of lead on children through (1) identification of individual local factors for lead exposure and (2) averting health disparity and inequalities at the state level.

Population-based comparison of biomarker concentrations for chemicals of concern among Latino-American and non-Hispanic white children

Differences in cultural and economic status may place ethnic subgroups of children at higher risk for exposure, leading to heightened health risks, and health inequities. Although Latino-Americans represent 22% of all children in the United States, few studies have explored within-group differences in their exposure to toxicants. Using socio-demographic and biomarker data from the National Health and Nutrition Examination Survey from 1999 to 2008, we characterized determinants of health and estimated geometric means of environmental contaminant biomarkers (blood concentrations of lead and mercury, serum concentrations of dichlorodiphenyldichloroethylene [p,p'-DDE] and cotinine, and urinary metabolites of organophosphate [OP] pesticides and polycyclic aromatic hydrocarbons [PAHs]) among 4,257 Mexican American (MA), 677 Other Latino-American (OL), and 3,370 Non-Hispanic White (NHW) children. MAs had the lowest levels of health insurance coverage and regular access to health care, and largest household size compared to NHWs and OLs. MAs had higher levels of p,p'-DDE, lead, and cadmium while OLs had higher estimates of mercury relative to other groups. MAs had higher urinary metabolite concentrations of 2-hydroxynaphthalene; otherwise MAs and OLs had lower concentrations of PAHs. NHWs had higher levels of cotinine and dimethylthiophosphate. For other OP metabolites, differences among groups were less clear. Lead and p,p'-DDE exposure differences likely reflect later and less regulatory control of these chemicals in Latin America. Additionally, poor quality housing with lead paint is more common in economically disadvantaged subpopulations. Dietary habits are possible sources of differential cadmium, mercury, and organophosphate exposure. Cotinine exposure differences by income and U.S.- vs. foreign-born may represent increased acculturation. These results, coupled with additional research on exposure sources may contribute to refinement of environmental health promotion programs for the fast-growing Latino-American population.

Associations between socioeconomic status and environmental toxicant concentrations in adults in the USA: NHANES 2001-2010

Low level chronic exposure to toxicants is associated with a range of adverse health effects. Understanding the various factors that influence the chemical burden of an individual is of critical importance to public health strategies. We investigated the relationships between socioeconomic status (SES) and bio-monitored chemical concentration in five cross-sectional waves of the U.S. National Health and Nutrition Examination Survey (NHANES). We utilised adjusted linear regression models to investigate the association between 179 toxicants and the poverty income ratio (PIR) for five NHANES waves. We then selected a subset of chemicals associated with PIR in 3 or more NHANES waves and investigated potential mediating factors using structural equation modelling. PIR was associated with 18 chemicals in 3 or more NHANES waves. Higher SES individuals had higher burdens of serum and urinary mercury, arsenic, caesium, thallium, perfluorooctanoic acid, perfluorononanoic acid, mono(carboxyoctyl) phthalate and benzophenone-3. Inverse associations were noted between PIR and serum and urinary lead and cadmium, antimony, bisphenol A and three phthalates (mono-benzyl, mono-isobutyl, mono-n-butyl). Key mediators included fish and shellfish consumption for the PIR, mercury, arsenic, thallium and perfluorononanoic acid associations. Sunscreen use was an important mediator in the benzophenone-3/PIR relationship. The association between PIR and cadmium or lead was partially mediated by smoking, occupation and diet. These results provide a comprehensive analysis of exposure patterns as a function of socioeconomic status in US adults, providing important information to guide future public health remediation measures to decrease toxicant and disease burdens within society.

Blood lead levels in schoolchildren living near an industrial zone in Cali, Colombia: the role of socioeconomic condition

This study aimed to determine Blood Lead Levels (BLL) in schoolchildren 6-14 years old exposed to industrial sources of lead and evaluated the role of socioeconomic condition. A cross-sectional study was conducted in an area likely to be exposed to industrial pollutants in northern Cali (i.e., distance and wind direction) and in a "non-exposed" area. In children in two schools of corresponding study areas, venous samples (5 ml) were collected to determine BLL by graphite furnace absorption spectrometry. Using regression models, we evaluated the association between risk factors to BLL and the effect of modification with variables of socioeconomic condition. We enrolled 350 schoolchildren. Schoolchildren in the exposed area had higher prevalence of BLL of ≥ 5 μg/dl (44.2 vs. 8.2 %, p = 0.000) than those in non-exposed area. A positive association was found between exposure and BLL of ≥ 5 μg/dl (prevalence ratios (PR), 6.68; 95 % confidence interval (95 % CI), 3.95, 11.29). Demographic characteristics and socioeconomic condition such as age (PR, 1.45; 95 % CI, 1.03, 2.04), sex (PR, 1.84; 95 % CI, 1.30, 2.60), race (PR, 2.32; 95 % CI, 1.39, 3.89) and socioeconomic position (SEP; PR, 2.02; 95 % CI, 1.35, 3.04) were statistically significant and independently associated with BLL. There was a synergistic interaction between exposure to the industrial zone and SEP for higher BLL (coefficient, 0.80; 95 % CI, 0.17, 1.43). Residence in the northern urban area of Cali exposed to pollutants of an industrial zone is associated to an increased risk of higher BLL, especially among children from low SEC who are at greater risk of exposure and susceptibility.

Experimental determination of the oral bioavailability and bioaccessibility of lead particles

In vivo estimations of Pb particle bioavailability are costly and variable, because of the nature of animal assays. The most feasible alternative for increasing the number of investigations carried out on Pb particle bioavailability is in vitro testing. This testing method requires calibration using in vivo data on an adapted animal model, so that the results will be valid for childhood exposure assessment. Also, the test results must be reproducible within and between laboratories. The Relative Bioaccessibility Leaching Procedure, which is calibrated with in vivo data on soils, presents the highest degree of validation and simplicity. This method could be applied to Pb particles, including those in paint and dust, and those in drinking water systems, which although relevant, have been poorly investigated up to now for childhood exposure assessment.

Associations between petrol-station density and manganese and lead in the cord blood of newborns living in Taiwan

Although the anti-knocking agents used in Taiwan do not contain manganese, there are relatively high concentrations of the element in diesel fuel. As such, there have been many concerns about the impact of exposure to diesel fuels on health. This study was conducted in Taiwan to investigate the relationship between the concentration of manganese in cord blood of Taiwanese newborns and the geographic density of petrol stations as a surrogate for determining manganese emissions from vehicular traffic. A total of 1526 full-term newborns without major congenital malformations were consecutively recruited from various medical facilities from May 2004 to July 2005. Questionnaires were completed by the newborns' mothers after delivery to collect information on demographic characteristics, medical history, living environment, and other factors. Cord blood samples were collected at birth and analyzed for manganese and lead using inductively coupled plasma mass spectrometry. The geographic density of petrol stations within a 10 km zone around each newborn's residence was calculated for 1343 newborns using the Arc9 Geographic Information System. The geometric means of cord blood manganese and lead concentrations were 47.0 μg/L (GSD=1.42) and 12.6 μg/L (GSD=1.76), respectively. After adjusting for potential confounding factors, including maternal age, and maternal education, the results of a multiple linear regression model indicated that the concentration of cord blood manganese increased monotonically with an increasing density of petrol stations. However, no such association was found for levels of lead in cord blood. Further smoothing spline model analysis indicated that a ten unit increment in petrol station density made cord blood manganese and lead levels change by factors of 1.0092 (95% CI: 1.0058, 1.0127) and 0.9994 (95% CI: 0.9890, 0.9998), respectively. This finding suggests that exposure to manganese-containing fuel from motor vehicles may result in elevated manganese levels in the fetus. Further research is warranted to explore the relationship between traffic-related manganese exposure and potential adverse effects on fetal development.

Potential for childhood lead poisoning in the inner cities of Australia due to exposure to lead in soil dust

This article presents evidence demonstrating that the historical use of leaded gasoline and lead (Pb) in exterior paints in Australia has contaminated urban soils in the older inner suburbs of large cities such as Sydney and Melbourne. While significant attention has been focused on Pb poisoning in mining and smelting towns in Australia, relatively little research has focused on exposure to Pb originating from inner-city soil dust and its potential for childhood Pb exposures. Due to a lack of systematic blood lead (PbB) screening and geochemical soil Pb mapping in the inner cities of Australia, the risks from environmental Pb exposure remain unconstrained within urban population centres.

Hunting with lead: association between blood lead levels and wild game consumption

BACKGROUND

Wild game hunting is a popular activity in many regions of the United States. Recently, the presence of lead fragments in wild game meat, presumably from the bullets or shot used for hunting, has raised concerns about health risks from meat consumption.

OBJECTIVE

This study examined the association between blood lead levels (PbB) and wild game consumption.

METHODS

We recruited 742 participants, aged 2-92 years, from six North Dakota cities. Blood lead samples were collected from 736 persons. Information on socio-demographic background, housing, lead exposure source, and types of wild game consumption (i.e., venison, other game such as moose, birds) was also collected. Generalized estimating equations (GEE) were used to determine the association between PbB and wild game consumption.

RESULTS

Most participants reported consuming wild game (80.8%) obtained from hunting (98.8%). The geometric mean PbB were 1.27 and 0.84 microg/dl among persons who did and did not consume wild game, respectively. After adjusting for potential confounders, persons who consumed wild game had 0.30 microg/dl (95% confidence interval: 0.16-0.44 microg/dl) higher PbB than persons who did not. For all game types, recent (<1 month) wild game consumption was associated with higher PbB. PbB was also higher among those who consumed a larger serving size (> or = 2 oz vs. <2 oz); however, this association was significant for 'other game' consumption only.

CONCLUSIONS

Participants who consumed wild game had higher PbB than those who did not consume wild game. Careful review of butchering practices and monitoring of meat-packing processes may decrease lead exposure from wild game consumption.

Pb2+: an endocrine disruptor in Drosophila?

Environmental exposure to Pb(2+) affects hormone-mediated responses in vertebrates. To help establish the fruit fly, Drosophila melanogaster, as a model system for studying such disruption, we describe effects of Pb(2+) on hormonally regulated traits. These include duration of development, longevity, females' willingness to mate, fecundity and adult locomotor activity. Developmental Pb(2+) exposure has been shown to affect gene expression in a specific region of the Drosophila genome (approximately 122 genes) involved in lead-induced changes in adult locomotion and to affect regulation of intracellular calcium levels associated with neuronal activity at identified synapses in the larval neuromuscular junction. We suggest ways in which Drosophila could become a new model system for the study of endocrine disruptors at genetic, neural and behavioral levels of analysis, particularly by use of genomic methods. This will facilitate efforts to distinguish between behavioral effects of Pb(2+) caused by direct action on neural mechanisms versus effects of Pb(+2) on behavior mediated through endocrine disruption.

Experimental manipulations blunt time-induced changes in brain monoamine levels and completely reverse stress, but not Pb+/-stress-related modifications to these trajectories

This study sought to further understand how environmental conditions influence the outcomes of early developmental insults. It compared changes in monoamine levels in frontal cortex, nucleus accumbens and striatum of male and female Long-Evans rat offspring subjected to maternal Pb exposure (0, 50 or 150ppm in drinking water from 2 months pre-breeding until pup weaning)+/-prenatal (PS) (restraint on GD16-17) or PS+offspring stress (OS; three variable stress challenges to young adults) determined at 2 months of age and at 6 months of age in littermates subsequently exposed either to experimental manipulations (EM: daily handling and performance on an operant fixed interval (FI) schedule of food reward), or to no experience (NEM; time alone). Time alone (NEM conditions), even in normal (control) animals, modified the trajectory of neurochemical changes between 2 and 6 months across brain regions and monoamines. EM significantly modified the NEM trajectories, and except NE and striatal DA, which increased, blunted the changes in monoamine levels that occurred over time alone. Pb+/-stress modified the trajectory of monoamine changes in both EM and NEM conditions, but these predominated under NEM conditions. Stress-associated modifications, occurring mainly with NEM OS groups, were fully reversed by EM procedures, while reversals of Pb+/-stress-associated modifications occurred primarily in nucleus accumbens, a region critical to mediation of FI response rates. These results extend the known environmental conditions that modify developmental Pb+/-stress insults, which is critical to ultimately understanding whether early insults lead to adaptive or maladaptive behavior and to devising behavioral therapeutic strategies. That time alone and a set of EM conditions typically used as outcome measures in intervention studies can themselves invoke neurochemical changes, moreover, has significant implications for experimental design of such studies.

Determination of toxic and essential elements in children's blood with inductively coupled plasma-mass spectrometry

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

Trends in blood lead levels and blood lead testing among US children aged 1 to 5 years, 1988-2004

OBJECTIVES

To evaluate trends in children's blood lead levels and the extent of blood lead testing of children at risk for lead poisoning from national surveys conducted during a 16-year period in the United States.

METHODS

Data for children aged 1 to 5 years from the National Health and Nutrition Examination Survey III Phase I, 1988-1991, and Phase II, 1991-1994 were compared to data from the survey period 1999-2004.

RESULTS

The prevalence of elevated blood lead levels, >/=10 microg/dL, among children decreased from 8.6% in 1988-1991 to 1.4% in 1999-2004, which is an 84% decline. From 1988-1991 and 1999-2004, children's geometric mean blood lead levels declined in non-Hispanic black (5.2-2.8 microg/dL), Mexican American (3.9-1.9 microg/dL), and non-Hispanic white children (3.1 microg/dL to 1.7 microg/dL). However, levels continue to be highest among non-Hispanic black children relative to Mexican American and non-Hispanic white children. Blood lead levels were distributed as follows: 14.0% were <1.0 microg/dL, 55.0% were 1.0 to <2.5 microg/dL, 23.6% were 2.5 to <5 microg/dL, 4.5% were 5 to <7.5 microg/dL, 1.5% were 7.5 to <10 microg/dL, and 1.4% were >/=10 microg/dL. Multivariable analysis indicated that residence in older housing, poverty, age, and being non-Hispanic black are still major risk factors for higher lead levels. Blood lead testing of Medicaid-enrolled children increased to 41.9% from 19.2% in 1988-1991. Only 43.0% of children with elevated blood lead levels had previously been tested.

CONCLUSIONS

Children's blood lead levels continue to decline in the United States, even in historically high-risk groups for lead poisoning. To maintain progress made and eliminate remaining disparities, efforts must continue to test children at high risk for lead poisoning, and identify and control sources of lead. Coordinated prevention strategies at national, state, and local levels will help achieve the goal of elimination of elevated blood lead levels.

Exposure of U.S. children to residential dust lead, 1999-2004: II. The contribution of lead-contaminated dust to children's blood lead levels

BACKGROUND

The U.S. Centers for Disease Control and Prevention collected health, housing, and environmental data in a single integrated national survey for the first time in the United States in 1999-2004.

OBJECTIVES

We aimed to determine how floor dust lead (PbD) loadings and other housing factors influence childhood blood lead (PbB) levels and lead poisoning.

METHODS

We analyzed data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES), including 2,155 children 12-60 months of age with PbB and PbD measurements. We used linear and logistic regression models to predict log-transformed PbB and the odds that PbB was >or=5 and >or=10 microg/dL at a range of floor PbD.

RESULTS

The population-weighted geometric mean (GM) PbB was 2.0 microg/dL (geometric standard error=1.0). Age of child, race/ethnicity, serum cotinine concentration, poverty-to-income ratio, country of birth, year of building construction, floor PbD by floor surface and condition, windowsill PbD, presence of deteriorated paint, home-apartment type, smoking in the home, and recent renovation were significant predictors in either the linear model [the proportion of variability in the dependent variable accounted for by the model (R2)=40%] or logistic model for 10 microg/dL (R2=5%). At floor PbD=12 microg/ft2, the models predict that 4.6% of children living in homes constructed before 1978 have PbB>or=10 microg/dL, 27% have PbB>or=5 microg/dL, and the GM PbB is 3.9 microg/dL.

CONCLUSIONS

Lowering the floor PbD standard below the current standard of 40 microg/ft2 would protect more children from elevated PbB.

Influence of low level maternal Pb exposure and prenatal stress on offspring stress challenge responsivity

We previously demonstrated potentiated effects of maternal Pb exposure producing blood Pb(PbB) levels averaging 39microg/dl combined with prenatal restraint stress (PS) on stress challenge responsivity of female offspring as adults. The present study sought to determine if: (1) such interactions occurred at lower PbBs, (2) exhibited gender specificity, and (3) corticosterone and neurochemical changes contributed to behavioral outcomes. Rat dams were exposed to 0, 50 or 150ppm Pb acetate drinking water solutions from 2 mos prior to breeding through lactation (pup exposure ended at weaning; mean PbBs of dams at weaning were <1, 11 and 31microg/dl, respectively); a subset in each Pb group underwent prenatal restraint stress (PS) on gestational days 16-17. The effects of variable intermittent stress challenge (restraint, cold, novelty) on Fixed Interval (FI) schedule controlled behavior and corticosterone were examined in offspring when they were adults. Corticosterone changes were also measured in non-behaviorally tested (NFI) littermates. PS alone was associated with FI rate suppression in females and FI rate enhancement in males; Pb exposure blunted these effects in both genders, particularly following restraint stress. PS alone produced modest corticosterone elevation following restraint stress in adult females, but robust enhancements in males following all challenges. Pb exposure blunted these corticosterone changes in females, but further enhanced levels in males. Pb-associated changes showed linear concentration dependence in females, but non-linearity in males, with stronger or selective changes at 50ppm. Statistically, FI performance was associated with corticosterone changes in females, but with frontal cortical dopaminergic and serotonergic changes in males. Corticosterone changes differed markedly in FI vs. NFI groups in both genders, demonstrating a critical role for behavioral history and raising caution about extrapolating biochemical markers across such conditions. These findings demonstrate that maternal Pb interacts with prenatal stress to further modify both behavioral and corticosterone responses to stress challenge, thereby suggesting that studies of Pb in isolation from other disease risk factors will not reveal the extent of its adverse effects. These findings also underscore the critical need to extend screening programs for elevated Pb exposure, now restricted to young children, to pregnant, at risk, women.