Environmental Lead Concentrations Research Articles

Assessment of the Long-Term Exposure to Lead in Four European Countries Using PBPK Modeling

Lead (Pb) is a naturally occurring heavy metal that received, in the last decades, much attention in the human health risk assessment community. In the European Human Biomonitoring Initiative (HBM4EU), Pb was identified as a priority substance as various scientific and policy questions were open and still to be answered. They included the further investigation of the internal exposure to Pb, the factors determining it, and its variations within European populations. The aim of this work was to develop an integrative modeling framework for the assessment of the aggregated long-term exposure to Pb in Belgium, Czech Republic, Germany, and Norway. This framework enabled predicting the concentrations of Pb in human blood (PbB) from estimates of the external exposure. The effect of past and current exposure events was accounted for, as multiple country-specific Pb concentration data in environmental compartments and diet, and estimates of the dietary intake of Pb covering a period from the 1970s until the present times were compiled. This modeling approach allowed, using a two-dimensional Monte Carlo (MC2D) approach, running a population-based simulation and characterizing the inter-individual variability within the simulated populations and the uncertainty on the external exposure estimates. The predicted PbB levels were compared with the results drawn from HBM data. To the best of our knowledge, this holistic modeling approach combines for the first time temporal and country-specific trends in environmental lead concentrations to derive internal exposure, in order to get better insights into the relationship between environmental and human lead exposure, and to characterize individual exposure at different ages.Graphical

Increased lead concentrations in the hairs of radiographers in general hospitals

This study investigated lead concentrations in the hairs of radiographers working in the radiological departments of general hospitals that used lead shielding for radiation protection. We collected scalp hair samples from 32 radiographers working in four radiology departments with lead shielding and 18 administration personnel in the same hospitals without lead shielding. Samples were analyzed for lead concentrations by inductively coupled plasma mass spectrometry. As a result, lead concentrations in the hairs of the radiological technologists were significantly higher than those in the administration staffs (0.72 ± 0.51 vs. 0.19 ± 0.27 μg/g, P < 0.001). The hair lead concentrations were positively and significantly associated with environmental lead concentrations (r = 0.6, P = 0.001), but not associated with age, working duration, and gender distribution.

Natural Lead Levels in Dandelions ( Taraxacum officinale): A Weed, Folk Medicine, and Biomonitor.

The natural lead concentration of dandelion ( Taraxacum officinale) leaves is estimated to be 0.2 μg/g (dry weight), or 1-3 orders of magnitude below most contemporary measurements of that value for dandelions and other plants. This estimate is based on analyses of lead concentrations of dandelions grown in a trace metal clean laboratory, with environmental lead concentrations approximating natural levels. The protocols used in this study paralleled those in our previous study that estimated the natural blood lead level in humans (0.016 μg/dL), which is also 1-3 orders of magnitude below most contemporary measurements. Analyses of the isotopic ratios (206Pb/207Pb:208Pb/207Pb) of the lead in the plants grown in the laboratory and greenhouse and those collected in the field, as well as the isotopic ratios of the soils the plants were grown in in the laboratory, indicate that anthropogenic lead makes up a substantial amount of labile lead in today's environments. Consequently, this estimate of the natural lead level in dandelion leaves provides both a benchmark for comparison of lead concentrations in contemporary plants and yet another measure of persistent lead contamination in the biosphere.

Evaluation and management of lead exposure.

Lead, which is widely used in industry, is a common element found in low concentrations in the Earth’s crust. Implementations to reduce environmental lead concentrations have resulted in a considerable reduction of lead levels in the environment (air) and a sustained reduction in the blood lead levels of the average citizen. However, people are still being exposed to lead through a variety of routes in everyday commodities.Lead causes health problems such as toxicity of the liver, kidneys, hematopoietic system, and nervous system. Having a carcinogenic risk as well, the IARC classifies inorganic lead compounds as probably carcinogenic to humans (Group 2A). Occupational lead poisonings have decreased due to the efforts to reduce the lead concentrations in the working environment. In contrast, health hazards associated with long-term environmental exposure to low concentrations of lead have been reported steadily. In particular, chronic exposure to low concentrations of lead has been reported to induce cognitive behavioral disturbances in children.It is almost impossible to remove lead completely from the human body, and it is not easy to treat health hazards due to lead exposure. Therefore, reduction and prevention of lead exposure are very important. We reviewed the toxicity and health hazards, monitoring and evaluation, and management of lead exposure.

Cadmium, lead and mercury exposure in non smoking pregnant women

Recent literature suggests that exposure to low concentrations of heavy metals may affect both maternal and child health. This study aimed to determine the biological heavy metals concentrations of pregnant women as well as environmental and dietary factors that may influence exposure concentrations. One hundred and seventy three pregnant women were recruited from Western Australia, each providing a sample of blood, first morning void urine, residential soil, dust and drinking water samples. Participants also completed a questionnaire which included a food frequency component. All biological and environmental samples were analysed for heavy metals using ICP-MS. Biological and environmental concentrations of lead and mercury were generally low (Median Pb Drinking Water (DW) 0.04µg/L; Pb soil <3.0µg/g; Pb dust 16.5µg/g; Pb blood 3.67µg/L; Pb urine 0.55; µg/L Hg DW <0.03; Hg soil <1.0µg/g; Hg dust <1.0µg/g; Hg blood 0.46µg/L; Hg urine <0.40µg/L). Cadmium concentrations were low in environmental samples (Median CdDW 0.02µg/L; Cdsoil <0.30ug/g; Cddust <0.30) but elevated in urine samples (Median 0.55µg/L, creatinine corrected 0.70µg/g (range <0.2–7.06µg/g creatinine) compared with other studies of pregnant women. Predictors of increased biological metals concentrations in regression models for blood cadmium were residing in the Great Southern region of Western Australia and not using iron/folic acid supplements and for urinary cadmium was having lower household annual income. However, these factors explained little of the variation in respective biological metals concentrations. The importance of establishing factors that influence low human exposure concentrations is becoming critical in efforts to reduce exposures and hence the potential for adverse health effects.

Lead isotope tracking of atmospheric response to post-industrial conditions in Yerevan, Armenia

Temporal gradients in environmental lead concentrations and isotopic compositions trace the rapidly shifting transition from high to low industrial emissions in Yerevan, Armenia following the dissolution of the Soviet Union in the early 1990s. Shortly after the breakup, in 1995 and 1996, atmospheric lead concentrations averaged ∼0.4 μg m −3 and the combustion of leaded gasoline was the primary source of industrial lead emissions in Yerevan. But by 1998, unleaded gasoline was predominant and atmospheric lead concentrations had decreased by two orders of magnitude to ⩽0.003 μg m −3 because industrial lead emissions from stationary sources had also been radically curtailed. The increased proportion of unleaded gasoline use is clearly seen in comparisons of the isotopic compositions of lead in air and gasoline. In 1998 and 1999, the isotopic composition of atmospheric lead (1.1605⩽ 206Pb/ 207Pb⩽1.1641) was comparable to that in soil (1.1357⩽ 206Pb/ 207Pb⩽1.1649); and it was markedly different from the average isotopic value of gasoline ( 206Pb/ 207Pb=1.1407 in 1998 and 1.1555 in 1999). Binary mixing calculations suggest that 75% of the atmospheric lead in 1998 was derived from re-suspended soil that retains lead from past emissions and 25% was derived from a mixture of present industrial emissions and uncontaminated soil. Anthropogenic lead persists in urban air, albeit at relatively low levels, despite leaded gasoline phase out and stationary emissions curtailment.

Longitudinal Study of Daily Intake and Excretion of Lead in Newly Born Infants

As an adjunct to a study of lead mobilization during pregnancy and lactation, we have obtained estimates of the daily lead intake and excretion/intake for 15 newly born infants monitored for at least 6 months postpartum. The longitudinal data presented reflect the far lower levels of environmental contribution to lead in blood in the 1990's than that in the earlier studies from the 1970's and early 1980's, the last period for which such dietary information is available in newly born infants. Infants were breast-fed or formula-fed or both and, in the second quarter, were usually fed solid foods (beikost). Lead concentrations were as follows: lead in breast milk, ranged from 0.09 to 3.1 μg/kg with a geometric mean of 0.55 μg/kg, lead in infant formula ranged from 0.07 to 11.4 μg/kg with a geometric mean of 1.6 μg/kg, and lead in beikost ranged from 1.1 to 27 μg/kg with a geometric mean of 2.9 μg/kg. Daily lead intakes ranged from 0.04 to 0.83 μg/kg body weight/day with a geometric mean of 0.23 μg Pb/kg body weight/day, and excretion/intake ranged from 0.7 to 22 with a geometric mean of 2.6. There was no significant difference at the 5% level in lead concentration in daily intakes and excretion/intake for the first quarter versus the second quarter for this small number of subjects. Assuming that there was no contribution from environmental samples such as house dust and ambient air, the contribution of diet to blood has been estimated from lead isotopic measurements with the following ranges: for breast milk only as the dietary source, 40 to 65%; for breast milk and infant formula as the dietary sources, 15 to 70%; and for infant formula and beikost, 20 to 80%. The geometric mean value of the dietary contribution to blood over the 6-month period of approximately 35% is consistent with earlier estimates of uptake of lead in blood in newly born infants when environmental lead concentrations were much higher. Other sources such as air, soil, and dust are considered to contribute minimally to blood lead in these infants because of the low 206Pb/204Pb ratios in environmental media. Thus, we consider that the increased excretion over intake, along with other evidence, reflects mobilization of infant tissues arising especially from rapid bone turnover at this stage of life; the tissue lead has been identified isotopically in urine.

Prevalence of elevated blood leads and exposure to lead in construction trades in Iowa and Illinois.

Despite lowering of the permissible exposure level for lead in construction from 200 to 50 microg/m3 in 1993, excessive lead exposure continues to be a problem. Relatively little data are available from the Midwestern U.S. on the environmental lead concentrations generated during various construction activities and the potential for worker exposure. This study characterized the prevalence of blood lead concentrations in high-risk construction trades in Iowa/Illinois, and identified risk factors for occupational exposure to lead in these construction workers. A sample of 459 workers was selected from the total population of all union members from trade groups of painters, plumbers/pipefitters, ironworkers, laborers, and electricians. Participants completed an interviewer-administered questionnaire obtaining information on demographics, symptoms, occupational history, work practices, personal protective equipment, and training. Venous blood samples were collected from each participant and analyzed for blood lead (using atomic absorption spectroscopy) and free erythrocyte protoporphyrin levels. Blood lead levels (BLLs) of construction workers ranged from 0.1 to 50 microg/dL. Geometric mean blood lead concentrations by trade group were: laborers (7.6 microg/dL, n = 80); painters (5.9 microg/dL, n = 83); ironworkers (5.2 microg/dL, n = 87); plumbers (4.4 microg/dL, n = 82); electricians (2.4 microg/dL, n = 91). Blood lead levels for painters and laborers were significantly higher than other trade groups, and levels for electricians were significantly lower (p < 0. 01). Participants reported working primarily on commercial and industrial projects including new construction, renovation, and demolition. There were significant differences between the types of projects performed by different trade groups with laborers performing more highway/bridge renovation (p < 0.01), and plumbers reporting more residential remodeling (p = 0.05), repair of water lines containing lead (p = 0.04), or work on lead joints (p < 0.01). In addition to trade, elevated blood lead levels were associated with the type of construction project (especially bridge renovation and residential remodeling) and activities that include welding, cutting, rivet busting. The age of the home in which the worker lived, and hobbies such as casting/smelting lead for bullets or sinkers, were also important risk factors. Compliance with OSHA's Construction Lead Standard, and implementation of good occupational health and safety practices in general, was poor. Blood lead levels of 459 construction workers differed by the type of trade, type of project and specific job activity owing to differences in the inherent exposure potential of each task. Although the numbers of workers performing lead abatement projects were small, the trend for lower BLL in this group provides evidence that training, implementation of engineering controls, and proper use of personal protective equipment such as respirators is effective in controlling lead poisoning.

Lead exposure in passerines inhabiting lead‐contaminated floodplains in the Coeur D'Alene River Basin, Idaho, USA

AbstractBlood collected from song sparrows (Melospiza melodia) and American robins (Turdus migratorius) captured with mist nets in a lead‐contaminated (assessment) area and nearby uncontaminated (reference) areas within the Coeur d'Alene Basin in northern Idaho was analyzed for δ‐aminolevulinic acid dehydratase activity (ALAD) and hematocrit levels, and livers were analyzed for lead. Mean ALAD inhibition in the assessment area was 51% in song sparrows and 75% in American robins. The proportion of the sampled population with ALAD inhibition &gt;50% was calculated to be 43% for song sparrows and 83% for American robins. Assessment area hematocrit values for song sparrows (x = 39.9) and American robins (x = 39.5) were lower than in reference areas (x = 42.4 for song sparrows and 40.2 for American robins); however, differences were not statistically significant (p &gt; 0.05). Significantly higher levels of lead (wet weight) were found in livers from song sparrows captured on the assessment area (x = 1.93 ppm) than on reference areas (x = 0.10 ppm) (p = 0.0079). Study results indicate that 43% (95% confidence interval [CI] = 12.9‐77.5%) of the song sparrows and 83% (95% CI = 41.8‐99.2%) of the American robins inhabiting the floodplain along the Coeur d'Alene River in the assessment area are being exposed to lead at levels sufficient to inhibit ALAD by &gt; 50%. Variability in lead exposure indicators was attributed to high variability in environmental lead concentrations in the Coeur d'Alene River Basin.

Calculating the interindividual geometric standard deviation for use in the integrated exposure uptake biokinetic model for lead in children.

The integrated exposure uptake biokinetic (IEUBK) model, recommended for use by the U.S. Environmental Protection Agency at residential Superfund sites to predict potential risks to children from lead exposure and to establish lead remediation levels, requires an interindividual geometric standard deviation (GSDi) as an essential input parameter. The GSDi quantifies the variability of blood lead concentrations for children exposed to similar environmental concentrations of lead. Estimates of potential risks are directly related to the GSDi, and therefore the GSDi directly impacts the scope of remediation at Superfund sites. Site-specific GSDi can be calculated for sites where blood lead and environmental lead have been measured. This paper uses data from blood and environmental lead studies conducted at the Bingham Creek and Sandy, Utah, Superfund sites to calculate GSDi using regression modeling, box modeling, and structural equation modeling. GSDis were calculated using various methods for treating values below the analytical method detection and quantitation limits. Treatment of nonquantifiable blood lead concentrations affected the GSDi more than the statistical method used to calculate the GSDi. For any given treatment, the different statistical methods produced similar GSDis. Because of the uncertainties associated with data in the blood lead studies, we recommend that a range of GSDis be used when analyzing site-specific risks associated with exposure to environmental lead instead of a single estimate. Because the different statistical methods produce similar GSDis, we recommend a simple procedure to calculate site-specific GSDi from a scientifically sound blood and environmental lead study.

Measurements of environmental lead contamination and human exposure.

The importance of accurate measurements of environmental lead exposure and toxicity is substantiated by analyses documenting the global contamination of the biosphere with industrial lead and the pervasiveness of measurable lead toxicity in human populations. Those data demonstrating environmental lead contamination and toxicity have, in part, led to regulations that limit the amount of lead in some products (e.g., paint, solder, and gasolines) in many industrialized countries. These regulations have resulted in a substantial reduction in some lead discharges to the environment. In spite of these reductions, current environmental lead levels are still often more than 10-fold, and sometimes more than 10,000-fold, higher than natural levels. Further, environmental lead concentrations are expected to remain elevated for a protracted period due to continued emissions of relatively large amounts of industrial lead to the environment and the persistence of contaminant lead in the environment. Discharges of contaminant lead have resulted in increases in organism and human lead levels comparable to increases documented in environmental matrices, as indicated by a recent estimate of the natural level of lead in blood of preindustrial humans (0.016 microgram/dL or 0.8 nM). This estimate is 175-fold lower than average blood lead levels in the United States (2.8 micrograms/dL or 140 nM) and 600-fold lower than the recently (1991) revised Centers for Disease Control (CDC) action level of concern for early toxic effects in children (10 micrograms/dL or 480 nM). The significance of these comparisons to public health is corroborated by numerous studies suggesting that there may be no lower threshold for sublethal toxicity in contemporary (i.e., lead-contaminated) humans. Those data also indicate that environmental lead concentrations that were previously considered innocuous may be deleterious to human health. It is apparent that the extent of sublethal lead toxicity in humans may be best addressed by studies that consider control populations possessing natural (i.e., preindustrial) lead burdens, as well as state-of-the-art, trace-metal-clean techniques and advanced instrumentation. Trace-metal-clean techniques are required to prevent the inadvertent lead contamination of samples, which has plagued many previous analyses of environmental and human lead levels. Advanced instrumentation is required to provide the sensitivity, accuracy, and precision that are needed to quantify the sublethal effects of lead concentrations at environmental levels of exposure. Fortunately, methodologies utilizing these advancements are now capable of addressing many of the important issues (e.g., lead biomolecular speciation, low exposure effects) in environmental and human lead toxicology.

Assessing the Relationship Between Environmental Lead Concentrations and Adult Blood Lead Levels

This paper presents a model for predicting blood lead levels in adults who are exposed to elevated environmental levels of lead. The model assumes a baseline blood lead level based on average blood lead levels for adults described in two recent U.S. studies. The baseline blood level in adults arises primarily from exposure to lead in diet. Media-specific ingestion and absorption parameters are assessed for the adult population, and a biokinetic slope factor that relates uptake of lead into the body to blood lead levels is estimated. These parameters are applied to predict blood lead levels for adults exposed to a hypothetical site with elevated lead levels in soil, dust and air. Blood lead levels ranging from approximately 3-57 micrograms/dl are predicted, depending on the exposure scenarios and assumptions.

Sources of lead pollution.

Environmental lead concentrations today are grossly increased over the natural levels, even far away from cities. Nevertheless, the results of the EEC survey1 (see box) seem reasonably reassuring so far, even for children specially exposed to lead. But even 2% of children exceeding the limit of 1-69 ptmol/l (35 [xg/100 mg) might be too many?that is, if slightly raised levels can cause subtle neurological impairment (see last article, p 1622). Young children tend to have higher blood lead concentrations, which will not be apparent from blood samples taken when they are older. Some studies carried out near factories producing lead pollution have shown considerably raised blood lead concen? trations in many preschool children, and also mothers.2 In Birmingham, although both the schoolchildren and the younger children surveyed had low mean blood concentrations, a worrying proportion of inner city preschool children had concentrations over 1-69 (jtmol/l.3 4 These were mostly Asians and their sources of lead exposure are being investigated, with a detailed dietary survey to look at both dietary lead content and possible nutritional deficiencies that would make them more susceptible to poor environmental conditions.