Lead, Soils, and Children: An Ecological Analysis of Lead Contamination in Parks and Elevated Blood Lead Levels in Brooklyn, New York

Metal(loid)s in urban soil from historical municipal solid waste landfill: Geochemistry, source apportionment, bioaccessibility testing and human health risks

Landfills, especially those poorly managed, can negatively affect the environment and human beings through chemical contamination of soils and waters. This study investigates the soils of a historical municipal solid waste (MSW) landfill situated in the heart of a residential zone in the capital of Slovakia, Bratislava, with an emphasis on metal (loid) contamination and its consequences. Regardless of the depth, many of the soils exhibited high metal (loid) concentrations, mainly Cd, Cu, Pb, Sb, Sn and Zn (up to 24, 2620, 2420, 134, 811 and 6220 mg/kg, respectively), classifying them as extremely contaminated based on the geo-accumulation index (Igeo >5). The stable lead isotopic ratios of the landfill topsoil varied widely (1.1679-1.2074 for 206Pb/207Pb and 2.0573-2.1111 for 208Pb/206Pb) and indicated that Pb contained a natural component and an anthropogenic component, likely municipal solid waste incineration (MSWI) ash and construction waste. Oral bioaccessibility of metal (loid)s in the topsoil was variable with Cd (73.2-106%) and Fe (0.98-2.10%) being the most and least bioaccessible, respectively. The variation of metal (loid) bioaccessibility among the soils could be explained by differences in their geochemical fractionation as shown by positive correlations of bioaccessibility values with the first two fractions of BCR (Community Bureau of Reference) sequential extraction for As, Cd, Mn, Ni, Pb, Sn and Zn. The results of geochemical fractionation coupled with the mineralogical characterisation of topsoil showed that the reservoir of bioaccessible metal (loid)s was calcite and Fe (hydr)oxides. Based on aqua regia metal (loid) concentrations, a non-carcinogenic risk was demonstrated for children (HI = 1.59) but no risk taking into account their bioaccessible concentrations (HI = 0.65). This study emphasises the need for detailed research of the geochemistry of wastes deposited in urban soils to assess the potentially hazardous sources and determine the actual bioaccessibility and human health risks of the accumulated metal (loid)s.

Blood lead, cadmium and hair mercury concentrations and association with soil, dust and occupational factors in e-waste recycling workers in Bangladesh

BACKGROUND

Electronic waste (e-waste) recycling activities release toxic metals, which pose substantial hazard to the environment and human health. We evaluated metal concentrations in biological and environmental samples, and examined the associations between biological lead (Pb), cadmium (Cd), and mercury (Hg) with soil and dust metals, and other possible determinants, among populations exposed and non-exposed to e-waste in Bangladesh.

METHODS

A total of 199 e-waste workers and 104 non-exposed individuals were recruited. We measured blood Pb (BPb) and Cd (BCd) concentrations and total Hg (THg) from hair samples. Data were collected on occupational, and behavioral factors. We fitted an elastic net regression (ENET) to model the relationship between a set of influencing factors and metals as outcome variables while controlling for potential covariates.

RESULTS

The median concentrations of BPb (11.89 μg/dL) and BCd (1.04 μg/L) among exposed workers were higher than those of non-exposed workers (BPb: 3.63 μg/dL and BCd: 0.83 μg/L respectively). A 100 ppm increment in soil Pb level was associated with an increase in ln-Pb (transformed) in blood (β = 0.002; 95% CI = 0.00, 0.02). Similarly, ln-BCd level increased (β = 0.02; 95% CI = 0.001, 0.07) with every ppm increase in dust Cd level. The number of years worked in e-waste activities was associated with elevated ln-BPb (β = 0.01; 95% CI = 0.01, 0.02) and ln-BCd levels (β = 0.003; 95% CI = 0.00, 0.05). Smoking significantly contributed to elevated levels of ln-BCd (β = 0.46; 95% CI = 0.43, 0.73). An increment of 100 kg of e-waste handling per week led to an increase in ln-BPb levels (β = 0.002; 95% CI = 0.00, 0.01), while respondents knowledge about adverse impact on e-waste reduced the ln-BPb level (β = -0.14; 95% CI = -0.31, -0.03). Fish consumption frequency had a positive association with THg in hair.

CONCLUSIONS

Our data show the need for workplace controls to reduce exposure to Pb and Cd with a broader view of exposure source taken.

Widespread Pb contamination in urban backyard soils for >100 years identified in soil cores constrained by 210Pb and 137Cs

Contaminated soil in urban residential areas is often overlooked as a source of childhood exposure to toxic levels of lead (Pb). We document mean Pb concentrations of 1200 ± 1000 mg/kg, three times the now outdated EPA soil hazard standard of 400 mg/kg, for 370 surface soils collected from 76 homes in the boroughs of Brooklyn and Manhattan of New York City. The mean Pb content of 250 ± 290 mg/kg Pb for 571 surface soils collected from tree pits and public parks was much lower. A subset of 22 surface samples analyzed by EPA Method 1340 extracted 86 ± 21 % (±1SD) of total soil Pb, indicating that it the Pb was highly bioavailable. To investigate the origin of backyard contamination, 49 cores were collected to an average depth of 30 cm from a subset of 27 homes. Twelve soil cores were analyzed for 210Pb and 137Cs to constrain processes that impact contaminant distribution and inventories (particle focusing, soil accumulation, loss, and mixing). Concentrations of Pb declined with depth in 60 % of the cores but usually did not reach background. Mean uncorrected Pb inventories of 340 ± 210 g/m2 Pb (mean ± 1SD, n = 12) were more than five times higher than the radionuclide corrected inventory of 57 g/m2 from Central Park soil cores. Average inventories of 210Pbxs (3.5 ± 0.9 kBq/m2) and 137Cs (0.9 ± 0.6 kBq/m2) corresponded to 71 ± 19 % and 50 ± 30 % of the predicted atmospheric inventories. Elevated Pb concentrations were found both in the fine (<1 mm) and coarse (>1 mm) fractions, the latter suggesting a local non-atmospheric source. This was confirmed by individual grains containing up to 6 % Pb and visible pieces of coal, bricks, and ash. Regardless of the source of contamination in backyard soils, systematic testing is needed to identify contaminated areas and reduce child exposure.

A global meta-analysis of the correlation between soil physicochemical properties and lead bioaccessibility

Soil physiochemical properties play a vital role in bioaccessibility-based health risk assessment as it can determine the bioaccessibility and the true risk of potentially toxic elements in soil. However, the effects of soil properties on bioaccessibility still remains unclear. In this paper, 17 of the 1454 literatures with 474 samples were identified, screened and reviewed for exploring the correlation between soil physicochemical properties and lead bioaccessibility (BAc_Pb) through a meta-analysis approach. Five soil physicochemical parameters including pH, SOM, Clay, CEC and T-Pb were systematically analyzed using Principal component analysis, Pearson correlation analysis and survival analysis. The results showed that pH of simulated gastric juice is a major source of heterogeneity of the correlation between soil pH and BAc_Pb. In the gastric phase, the effect of alkaline soil on high BAc_Pb (BAc >50%) is more sensitive, and the effect of acidic soil on low BAc_Pb (BAc <50%) is more sensitive. However, in the small intestinal phase, soil pH displays little impacts on BAc_Pb in acidic, alkaline and neutral soils. Although three principal components explained 66.2% and 64.9% of the total variance of the urban, agricultural, and mining soils in gastric and small intestinal phases, respectively, there was no strong evidence that soil type can influence the BAc_Pb. The results of present study provide insights into the correlation between soil properties and BAc_Pb, and prediction of the bioaccessibility and bioavailability of Pb in different types of soil.

Lead exposure in childhood and historical land use: a geostatistical analysis of soil lead concentrations in South Philadelphia parks

Elevated soil lead (Pb) concentrations in public parks and outdoor spaces continue to have a significant impact on the public health of urban communities. This study evaluated the geospatial and statistical relationships between soil Pb concentrations, the urban environment, and child blood lead levels (BLLs) in the neighborhood of South Philadelphia, PA. Soil samples (n = 240) were collected from forty (40) public parks and analyzed for Pb using a field portable X-ray fluorescence (XRF) analyzer. Geospatial mapping was used to investigate historical land use of each park, vehicular traffic on adjacent roadways, and density of residential/commercial development. Predicted child BLLs and BLL "high-risk areas" were identified using interpolation and biokinetic modeling. Childhood BLL data for South Philadelphia (n = 10,379) was provided by the Philadelphia Department of Public Health (2013-2015). Of the two hundred forty (240) soil samples collected, Pb levels for 10.8% of samples were ≥ 400 ppm. Two hundred sixty-nine of 10,379 children screened were identified with BLLs ≥ 5 µg/dL. Historical land use of each park was shown to be significantly correlated (p = 0.01) with soil Pb concentrations and child BLLs ≥ 5 µg/dL. Approximately 13.3% of the variance in child BLLs ≥ 5 µg/dL was attributed to historical site land use. Overall, undeveloped/greenspace historical land use exhibited the highest soil Pb concentrations in the study. Geospatial relationships were identified between census tracts with higher percentages of children with BLLs ≥ 5 µg/dL and interpolated BLL "high-risk" areas (≥ 3.5 µg/dL). The results of this study suggest soil accumulation time and historical land use may influence soil Pb concentrations and child BLLs in urban communities. Measured soil Pb concentrations were determined to effectively model community-wide contamination and childhood Pb exposure.

Identification of Legacy and Active Sources of Metal Contamination in Soils in Brooklyn, NY

The purpose of this study was to examine the spatial distribution and potential anthropogenic sources of lead (Pb), zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe) in surface soils throughout Brooklyn, NY. We collected soil samples (n = 1,373) from 176 different New York City parks. Samples were analyzed ex-situ using a portable X-ray fluorescence with a subset of samples laboratory confirmed. The effect of multiple sources on concentrations were determined by multivariable linear regression with generalized estimating equations. Median concentrations of Pb, Zn, Cu, Fe, and Mn were 108 ppm, 145 ppm, 49 ppm, 14,034 ppm, and 279 ppm, respectively. All metals were significantly correlated with one another (p < 0.001), with the strength of the correlation ranging from a low of approximately ρ = 0.3 (Pb-Mn and Zn-Mn) to a high of ρ = 0.7 (Pb-Cu). In final multivariate modeling significant association were observed between scrap yards and Mn concentration (β = 0.075, 0.019), National Priorities List (NPL) sites and Pb, Fe and Mn (β = 0.134, p = 0.004; β = 0.038, p = 0.014; β = 0.057, p = 0.037, respectively), and bridges nearby and Pb and Zn (β = 0.106, p = 0.003; β = 0.076, p = 0.026, respectively). Although manufacturing and industry have mostly left the area, smaller scrap metal recyclers are abundant and associated with increased Cu and Mn soil concentrations. In addition, NPL sites contributed to increased concentrations of all five metals within 800 m. Roadways have long been established to be sources of urban pollution; however, in our study we also found the presence of bridges within 800 m were also strongly predictive of increased Pb, Cu, and Zn concentrations.