[Use of urine lead level as an exposure indicator and its relationship to blood lead]

Spatial pattern of the environmental exposure to tin in the vicinity of an alloy industry in Volta Redonda, Rio de Janeiro State, Brazil

Despite being widely used in industry, the literature on tin and its effects in humans is scarce, especially regarding reference values in biological indicators such as blood and urine. Similarly, environmental limits are also rare. This study sought to assess the spatial distribution of hotspots in the environmental exposure to tin in the vicinity of an alloy industry in the south region of the state of Rio de Janeiro, Brazil. The study population consisted of 74 adults. Graphite furnace atomic absorption spectrometry determined tin in all samples. Households and points around the industry were georeferenced with the use of GPS to identify the most intense tin sites. Results of the first and second campaigns ranged from 0.022 to 0.153 and 0.003 to 0.445µg m-3 for the atmospheric air, whereas such ranges were 0.64 to 1.61 and 1.97 to 8.54µg m-2 for household dust, respectively. The mean tin concentration found in the blood of the population was 3.85 ± 1.57µg L-1. In urine the value was 3.56 ± 1.88µg L-1. The kernel map showed the highest spatial concentrations of tin in household dust in the eastern region of the industry. In the first sampling, atmospheric air samples presented the most elevated concentrations in the southwest and southeast. Although the direction of the wind was northwest, potentially high risks were concentrated in the central area in the second collection. The largest hotspots were in the north, south and southeast regions; however, urine samples showed medium to high levels in the west and east regions. Regarding blood samples, the greatest difference was the absence of hotspot areas in the west. Environmental monitoring becomes necessary to better assess the exposure to tin.

Urinary Lead Concentration Is an Independent Predictor of Cancer Mortality in the U.S. General Population

Lead is a ubiquitous pollutant that constitutes an environmental hazard worldwide. Although lead has been known as a carcinogenic factor in animal models, its role in human carcinogenesis is still a topic of debate with limited epidemiological evidence. Moreover, the association between urinary lead, as the most non-invasive and accessible way for lead measurement in human, and cancer mortality in general population has never been explored. We addressed this subject using continuous National Health and Nutrition Examination Survey 1999-2010 data and its Mortality Follow-Up Study. Of 5,316 subjects in study population, 161 participants died due to cancer. Cancer-specific mortality was associated with urinary lead levels after multivariable adjustment. Kaplan-Meier survival curve and cubic regression spline analyses indicated that high concentration of urinary lead exhibited significant association with raised death rate of cancer. Despite the marked decrease in environmental lead levels over the past three decades, lead exposure is still the significant determinant of cancer mortality in general population in U.S., and quantification of urinary lead may serve as a non-invasive approach to facilitate biomarker discovery and clinical translational research.

Lead and mercury levels in an environmentally exposed population in the Central Brazil

The objective was to assess the level of exposure to lead and mercury in a population in the Pantanal region in Mato Grosso State, Brazil. Blood lead (PbB) (n = 119) and urinary mercury (HgU) (n = 109) in local residents were measured by atomic absorption spectrometry. Comparison of means and correlations between variables used analysis of variance (ANOVA) and linear regression, respectively, with 95% confidence intervals. Mean PbB was 2.82 ± 1.53µg dL-1. The comparison of PbB stratified by collection site (p ≤ 0.01), work activity (p ≤ 0.01), and consumption of locally produced cow's milk (p ≤ 0.05) showed statistically significant differences. There were also positive associations between PbB and collection site (p ≤ 0.01), participants' profession (p ≤ 0.05), local milk (p ≤ 0.01), and source of drinking water (p ≤ 0.01). Mean HgU was 1.41 ± 0.98µg L-1. The levels only showed significant differences for participants' profession (p ≤ 0.01), and positive associations emerged between HgU and work activity (p ≤ 0.01) and body mass index (p ≤ 0.01). The samples showed low lead and mercury levels, similar to those found in other environmentally exposed populations. Despite these low concentrations, current knowledge on the toxicity of these metals shows that health effects can already be felt at levels that were previously considered safe, thus characterizing a health hazard.

Reduction of in utero lead exposures in South African populations: Positive impact of unleaded petrol

Background

Prenatal exposure to lead (Pb) has been shown to have negative and irreversible health impacts on foetal and early childhood development, affecting morbidity and mortality in adulthood. This study aimed to assess in utero Pb exposure, examine birth outcomes, and identify confounding factors in the large cohort of South African population, following the legislated removal of Pb from petrol.

Methods

Lead was measured in the maternal blood, urine and cord blood using Inductive Coupled Plasma Mass spectrometry (ICP-MS). The statistical analyses included Spearman’s correlation, Wilcoxon rank sum (Mann Whitney), Kruskal-Wallis rank tests and multivariate linear regression.

Results

Overall, the geometric mean (GM) of Pb in maternal blood (PbB) was 1.32 μg/dL (n = 640; 95% CI, 1.24–1.40). In the subset cohort, the GM of paired maternal PbB and cord blood (PbC) was 1.73 μg/dL (n = 350; 95% CI, 1.60–1.86) and 1.26 μg/dL (n = 317; 95% CI, 1.18–1.35), respectively with a positive correlation between the log PbB and the log PbC (rho = 0.65, p = <0.001). Birth outcomes showed geographical differences in the gestational age (p<0.001), birth length (p = 0.028) and head circumference (p<0.001), Apgar score at 5 min (p<0.001) and parity (p<0.002). In female neonates, a positive association was found between PbC and head circumference (rho = 0.243; p<0.016). The maternal PbB levels were positively correlated with race, educational status, water sources, cooking fuels and use of pesticides at home.

Conclusions

This study has demonstrated not only the positive impact that the introduction of unleaded petrol and lead-free paint has had on in utero exposure to Pb in South Africa, but has also contributed new data on the topic, in a region where such data and scientific investigations in this field are lacking. Future research should evaluate if similar effects can be detected in young children and the adult population.

Exposure to multiple chemicals in a cohort of reproductive-aged Danish women

BACKGROUND

Current exposure assessment research does not sufficiently address multi-pollutant exposure and their correlations in human media. Understanding the extent of chemical exposure in reproductive-aged women is of particular concern due to the potential for in utero exposure and fetal susceptibility.

OBJECTIVES

The objectives of this study were to characterize concentrations of chemical biomarkers during preconception and examine correlations between and within chemical classes.

METHODS

We examined concentrations of 135 biomarkers from 16 chemical classes in blood and urine from 73 women aged 18-40 enrolled in Snart Foraeldre/Milieu, a prospective cohort study of pregnancy planners in Denmark (2011-2014). We compared biomarker concentrations with United States similarly-aged, non-pregnant women who participated in the National Health and Nutrition Environmental Survey (NHANES) and with other international biomonitoring studies. We performed principal component analysis to examine biomarker correlations.

RESULTS

The mean number of biomarkers detected in the population was 92 (range: 60-108). The most commonly detected chemical classes were phthalates, metals, phytoestrogens and polycyclic aromatic hydrocarbons. Except blood mercury, urinary barium and enterolactone, geometric means were higher in women from NHANES. Chemical classes measured in urine generally did not load on a single component, suggesting high between-class correlation among urinary biomarkers, while there is high within-class correlation for biomarkers measured in serum and blood.

CONCLUSIONS

We identified ubiquitous exposure to multiple chemical classes in reproductive-aged Danish women, supporting the need for more research on chemical mixtures during preconception and early pregnancy. Inter- and intra-class correlation between measured biomarkers may reflect common exposure sources, specific lifestyle factors or shared metabolism pathways.

Lead, Arsenic, and Manganese Metal Mixture Exposures: Focus on Biomarkers of Effect

The increasing exposure of human populations to excessive levels of metals continues to represent a matter of public health concern. Several biomarkers have been studied and proposed for the detection of adverse health effects induced by lead (Pb), arsenic (As), and manganese (Mn); however, these studies have relied on exposures to each single metal, which fails to replicate real-life exposure scenarios. These three metals are commonly detected in different environmental, occupational, and food contexts and they share common neurotoxic effects, which are progressive and once clinically apparent may be irreversible. Thus, chronic exposure to low levels of a mixture of these metals may represent an additive risk of toxicity. Building upon their shared mechanisms of toxicity, such as oxidative stress, interference with neurotransmitters, and effects on the hematopoietic system, we address putative biomarkers, which may assist in assessing the onset of neurological diseases associated with exposure to this metal mixture.

Blood lead concentrations in Jamaican children with and without autism spectrum disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder manifesting by early childhood. Lead is a toxic metal shown to cause neurodevelopmental disorders in children. Several studies have investigated the possible association between exposure to lead and ASD, but their findings are conflicting. Using data from 100 ASD cases (2–8 years of age) and their age- and sex-matched typically developing controls, we investigated the association between blood lead concentrations (BLC) and ASD in Jamaican children. We administered a questionnaire to assess demographic and socioeconomic information as well as exposure to potential lead sources. We used General Linear Models (GLM) to assess the association of BLC with ASD status as well as with sources of exposure to lead. In univariable GLM, we found a significant difference between geometric mean blood lead concentrations of ASD cases and controls (2.25 μg/dL cases vs. 2.73 μg/dL controls, p < 0.05). However, after controlling for potential confounders, there were no significant differences between adjusted geometric mean blood lead concentrations of ASD cases and controls (2.55 μg/dL vs. 2.72 μg/dL, p = 0.64). Our results do not support an association between BLC and ASD in Jamaican children. We have identified significant confounders when assessing an association between ASD and BLC.

Direct determination of tin in whole blood and urine by GF AAS

OBJECTIVE

The aim of this work was to develop a procedure for the determination of tin in whole blood and urine by GF AAS with a minimum sample pre-treatment, using Pd/Mg as chemical modifier.

DESIGN AND METHODS

The analyses of tin were conducted using an atomic absorption spectrometer with Zeeman background correction. The laboratory staff volunteered blood and urine samples for the experimental studies and application of the methodology.

RESULTS

Samples were just diluted with 0.2% v/v Triton X-100, and pyrolysis and atomization temperatures of 1300 and 2200 °C were used. External calibration was performed with matrix matched calibration solutions. Limits of detection of 2.7 and 0.8 μgL(-1) were reached for blood and urine, respectively. The method was applied to the determination of Sn in blood and urine of eleven subjects not occupationally exposed, working in a laboratory of toxicology in a large Brazilian city, and the results ranged from 7.4 to 11.2 μgL(-1) and ≤0.8 to 2.2 μgL(-1), for blood and urine, respectively. Accuracy was assessed by analysis of standard reference materials for tin in blood (Contox I, lot TM144-1097, Kaulson Laboratories, USA) and urine (Seronorm, lot 0511545, Sero AS, Norway).

CONCLUSIONS

Results showed good agreement between experimental and reference values according to the Student's t test at 95% of confidence.

Evaluation of association between biomarkers of lead exposure in Sardinian children (Italy)

The aim of this work is to verify whether there are statistically significant correlations between the concentrations of lead in blood, urine, and hair in children. The sample collected in 2007 consists of 163 children of both sexes from 11-14-year-olds, living in three municipalities of Sardinia (Italy). Inductively coupled plasma atomic mass spectrometry has been used in the determination of lead concentration in biological material. For the overall sample, there is a non-significant partial correlation among the three matrices. However, for subjects with blood lead levels ≥5 μg/dL, there is a significant positive partial correlation between the lead levels in blood and hair, but not between blood and urine or between urine and hair. The results suggest that blood is the preferred biomarker to ascertain lead exposure in human populations, whereas hair can be used as a tool screening when an area is exposed to medium or high lead pollution.