Colder-to-warmer changes in children's blood lead concentrations are related to previous blood lead status: results from a systematic review of prospective studies

A national survey of lead and other metal(loids) in residential drinking water in the United States

BACKGROUND

Exposure to lead (Pb), arsenic (As) and copper (Cu) may cause significant health issues including harmful neurological effects, cancer or organ damage. Determination of human exposure-relevant concentrations of these metal(loids) in drinking water, therefore, is critical.

OBJECTIVE

We sought to characterize exposure-relevant Pb, As, and Cu concentrations in drinking water collected from homes participating in the American Healthy Homes Survey II, a national survey that monitors the prevalence of Pb and related hazards in United States homes.

METHODS

Drinking water samples were collected from a national survey of 678 U.S. homes where children may live using an exposure-based composite sampling protocol. Relationships between metal(loid) concentration, water source and house age were evaluated.

RESULTS

18 of 678 (2.6%) of samples analyzed exceeded 5 µg Pb L-1 (Mean = 1.0 µg L-1). 1.5% of samples exceeded 10 µg As L-1 (Mean = 1.7 µg L-1) and 1,300 µg Cu L-1 (Mean = 125 µg L-1). Private well samples were more likely to exceed metal(loid) concentration thresholds than public water samples. Pb concentrations were correlated with Cu and Zn, indicative of brass as a common Pb source is samples analyzed.

SIGNIFICANCE

Results represent the largest national-scale effort to date to inform exposure risks to Pb, As, and Cu in drinking water in U.S. homes using an exposure-based composite sampling approach.

IMPACT STATEMENT

To date, there are no national-level estimates of Pb, As and Cu in US drinking water collected from household taps using an exposure-based sampling protocol. Therefore, assessing public health impacts from metal(loids) in drinking water remains challenging. Results presented in this study represent the largest effort to date to test for exposure-relevant concentrations of Pb, As and Cu in US household drinking water, providing a critical step toward improved understanding of metal(loid) exposure risk.

Rapid and simple lead service line detection screening protocol using water sampling

Many water systems are challenged with uncertainty regarding service line material type. This work investigated using a simple drinking water flushed sampling approach and a more complicated and invasive sequential profile sampling approach to predict whether homes had an existing lead service line (LSL). Homes that never had an LSL (control groups) and homes with LSLs (study groups) in two communities having different degrees of corrosion control were sampled. Using control groups' results, community-specific "threshold" lead levels were determined and compared to results from study groups. The flushed sampling maximum lead concentration (FMC) of lead accurately predicted 100% and 60% of LSL sites for the community with poor and good corrosion control, respectively. The weighted average sequential profile lead concentration (WASLC) increased the 40% not identified as LSL sites by fully flushed samples to 100%. The WASLC closely followed by the maximum sequential profile lead concentration were most reliable in identifying LSLs.

A prospective study of maternal 25-hydroxyvitamin D (25OHD) in the first trimester of pregnancy and second trimester heavy metal levels

BACKGROUND

Vitamin D facilitates the absorption of calcium but may also increase absorption of other metals; the literature is conflicting.

OBJECTIVE

To examine whether 25OHD in the first trimester of pregnancy was associated with subsequent metals levels in the late second trimester of pregnancy.

METHODS

We used data from a sample of women in the LIFECODES pregnancy cohort (N = 381). 25-hydroxyvitamin D (25OHD) was measured with a chemiluminescence immunoassay in plasma samples drawn at 10 weeks of gestation. A panel of 17 metals and elements was measured in urine collected at 26 weeks of gestation. We used linear or logistic regression to estimate associations between 25OHD (dichotomous, linear, and in tertiles) and either urinary metal concentrations or the proportion of samples below the limit of detection, respectively. Multivariable models included urinary specific gravity, age, race/ethnicity, education, body mass index, insurance type, gestational age, and season.

RESULTS

After multivariable adjustment, low 25OHD was associated with a 47% increase in lead level, a 60% increase in tin level, and 1.58 times the odds of detectable tungsten. A 10 ng/ml increase in 25OHD was associated with a 12% decrease in tin and an 8% increase in molybdenum. While we had a small sample size, we found some evidence of effect modification by race. Women who reported their race as Black or were classified in the other race category, who also had low 25OHD, had 40% higher thallium than women with higher 25OHD and were more likely to have detectable beryllium and tungsten. These metals were not associated with low 25OHD in women who reported their race as White. Tin and lead were higher in women with low 25OHD in all race groups.

DISCUSSION

In total, further research is warranted to determine if vitamin D levels alter metal levels, and to elucidate the shape of the association for each metal across a range of corresponding 25OHD levels, and longitudinally, across pregnancy. This is especially true for pregnant people as exposure to metals during pregnancy has health consequences for the fetus.

Child lead exposure near abandoned lead acid battery recycling sites in a residential community in Bangladesh: Risk factors and the impact of soil remediation on blood lead levels

Lead is a potent neurotoxin that is particularly detrimental to children's cognitive development. Batteries account for at least 80% of global lead use and unsafe battery recycling is a major contributor to childhood lead poisoning. Our objectives were to assess the intensity and nature of child lead exposure at abandoned, informal used lead acid battery (ULAB) recycling sites in Kathgora, Savar, Bangladesh, as well as to assess the feasibility and effectiveness of a soil remediation effort to reduce exposure. ULAB recycling operations were abandoned in 2016 due to complaints from residents, but the lead contamination remained in the soil after operations ceased. We measured soil and blood lead levels (BLLs) among 69 children living within 200 m of the ULAB recycling site once before, and twice after (7 and 14 months after), a multi-part remediation intervention involving soil capping, household cleaning, and awareness-raising activities. Due to attrition, the sample size of children decreased from 69 to 47 children at the 7-month post-intervention assessment and further to 25 children at 14 months. We conducted non-parametric tests to assess changes in soil lead levels and BLLs. We conducted baseline surveys, as well as semi-structured interviews and observations with residents throughout the study period to characterize exposure behaviors and the community perceptions. We conducted bivariate and multivariate regression analyses of exposure characteristics to determine the strongest predictors of baseline child BLLs. Prior to remediation, median soil lead concentrations were 1400 mg/kg, with a maximum of 119,000 mg/kg and dropped to a median of 55 mg/kg after remediation (p < 0.0001). Among the 47 children with both baseline and post-intervention time 1 measurements, BLLs dropped from a median of 21.3 μg/dL to 17.0 μg/dL at 7 months (p < 0.0001). Among the 25 children with all three measurements, BLLs dropped from a median of 22.6 μg/dL to 14.8 μg/dL after 14 months (p < 0.0001). At baseline, distance from a child's residence to the nearest abandoned ULAB site was the strongest predictor of BLLs and baseline BLLs were 31% higher for children living within 50 m from the sites compared to those living further away (n = 69, p = 0.028). Women and children spent time in the contaminated site daily and relied on it for their livelihoods and for recreation. Overall, this study highlights the intensity of lead exposure associated with the ULAB recycling industry. Additionally, we document the feasibility and effectiveness of a multi-part remediation intervention at a contaminated site embedded within a residential community; substantially reducing child BLLs and soil lead concentrations.

Vitamin D Treatment during Pregnancy and Maternal and Neonatal Cord Blood Metal Concentrations at Delivery: Results of a Randomized Controlled Trial in Bangladesh

BACKGROUND

Vitamin D improves absorption of calcium; however, in animal studies vitamin D also increases the absorption of toxic metals, such as lead and cadmium.

OBJECTIVES

We examined maternal and neonatal cord blood levels of lead, cadmium, manganese, and mercury after supplementation with vitamin D during pregnancy.

METHODS

The Maternal Vitamin D for Infant Growth trial was a randomized, placebo-controlled, multi-arm study of maternal vitamin D supplementation during pregnancy in Dhaka, Bangladesh (NCT01924013). Women were randomized during their second trimester to blinded weekly doses of placebo or 4,200, 16,800, or 28,000 IU of vitamin D3 throughout pregnancy. Each group had 118-239 maternal blood specimens and 100-201 cord blood samples analyzed. Metals were measured using inductively coupled plasma mass spectrometry. Unadjusted estimates from linear regression models were expressed as percentage differences. Cord blood cadmium was analyzed as detectable or undetectable with log-binomial regression.

RESULTS

Maternal cadmium, mercury, and manganese levels were nearly identical across groups. Maternal lead levels were 6.3%, 7.4%, and 6.0% higher in the treatment groups (4,200, 16,800, and 28,000 IU, respectively) vs. placebo; however, 95% confidence intervals (CIs) showed that differences from 4.1% lower to 20% higher were compatible with the data. In treatment groups (4,200, 16,800, 28,000 IU) vs. placebo, neonatal cord blood lead levels were 8.5% (95% CI: - 3.5 , 22), 16% (95% CI: 3.3, 30), and 11% (95% CI: 0.4, 23) higher and had higher risk of detectable cadmium, relative risk ( RR ) = 2.2 (95% CI: 1.3, 3.7), RR = 1.4 (95% CI: 0.8, 2.5), RR = 1.7 (95% CI: 1.0, 2.9).

DISCUSSION

Vitamin D supplementation from the second trimester of pregnancy did not influence maternal cadmium, mercury, or manganese levels at delivery. Vitamin D was associated with nonsignificant increases in maternal lead and with significant increases in cord blood lead and cadmium. These associations were not dose dependent. Given that there are no safe levels of metals in infants, the observed increases in cord blood lead and cadmium require further exploration. https://doi.org/10.1289/EHP7265.

Blood Lead Levels in Females of Childbearing Age in Flint, Michigan, and the Water Crisis

OBJECTIVE

To compare blood lead levels in females of childbearing age, 12-50 years, living within and adjacent to Flint, Michigan, before, during, and after the Flint River water exposure and compare the levels to those that have been shown to cause fetal loss and preterm birth.

METHODS

The switch in the community water source to the Flint River occurred on April 25, 2014, and was reverted to the original source on October 15, 2015. Using a retrospective cross-sectional study design using geocoded blood lead levels obtained from all females of childbearing age available from a single hospital database, we compared blood lead levels for the following 18-month time periods: April 25, 2012-October 15, 2013 (PRE), April 25, 2014-October 15, 2015 (DURING), and April 25, 2016-October 15, 2017 (POST).

RESULTS

Results are reported as geometric mean (95% CI). Within Flint, PRE blood lead levels in females of childbearing age were 0.69 micrograms/dL (95% CI 0.63-0.75), DURING blood lead levels were 0.65 micrograms/dL (95% CI 0.60-0.71), and POST blood lead levels were 0.55 micrograms/dL (95% CI 0.54-0.56). DURING Flint River water exposure blood lead levels were not significantly different than the PRE Flint River water time period. POST Flint River water exposure blood lead levels were significantly lower than both PRE and DURING levels. Overall, lower blood lead levels were found outside the Flint boundary in all cohorts.

CONCLUSION

Blood lead levels in Flint females of childbearing age did not increase during the Flint River water exposure and subsequent 18-month time period. Mean blood lead levels during the Flint River water exposure are not consistent with the markedly higher blood lead levels reported in the literature to be associated with fetal loss, low birth weight, or preterm birth.

Lead seasonality in humans, animals, and the natural environment

Lead adversely impacts the health of humans, animals, and the natural environment. Higher lead burdens in warm weather occur in humans, domesticated and wild animals; land and water species; urban and rural, developed and pristine environments. The array of evidence suggests that lead seasonality is multifactorial within the natural world, including humans. Seasonally higher temperatures, solar radiation, humidity and anthropogenic pollution result in lower pH (acidification) in air, water and soil. Environmental acidification increases lead's bioavailability and mobility thus intensifying human, animal and plant exposures. In addition, lead seasonality in the biosphere is influenced by higher growth rates, slightly increased exposures, and more Vitamin D metabolism. Methodologically, we applied a One Health perspective to EPA's Integrated Science Assessments of Lead to review the published literature, supplemented with subsequent and related publications to assess data on the seasonality of lead exposure across species and through the earth's systems. Our integrated assessment suggests that: 1) 'Seasonality' is a multifactorial, terrestrial phenomenon affecting the natural world; human activities have exacerbated natural cyclicities that impact lead exposures across species. 2) To be sustainable, human lead remediation strategies must consider the total environment. 3) Global warming and climate change events may increase lead exposures and toxicity to all species throughout the natural environment.

Analysis of blood lead levels of young children in Flint, Michigan before and during the 18-month switch to Flint River water

Background: The toxicity of lead, like any xenobiotic, is directly linked to the duration of exposure and toxin concentration in the body. The elevation in blood lead levels (BLLs) in young Flint, Michigan children noted in time-periods before, and during the 18-month exposure to Flint River water (FRW) from 25 April 2014 to 15 October 2015 is well-known internationally. The length of time BLLs were elevated is unknown, yet key in understanding the potential health impact of the event. The objective of this study was to evaluate whether BLLs in Flint children were increased during the entire 18-month FRW exposure compared to similar earlier time periods. Methods: We conducted a retrospective study analyzing BLLs from Flint children aged 5 years and under. The geometric mean (GM) BLLs and percentages of BLLs ≥5.0 μg/dL in Period I: 25 April 2006 to 15 October 2007 (earliest timeframe available for study) and Period II: 25 April 2012 to 15 October 2013 (timeframe immediately before the water switch), were compared to Period III, 25 April 2014 to 15 October 2015 (FRW exposure). Results: There were 5663 BLLs available for study. GM ± SE BLLs decreased from 2.19 ± 0.03 μg/dL in Period I to 1.47 ± 0.02 μg/dL in Period II [95% CI, 0.64, 0.79]; p<.001 and decreased further to 1.32 ± 0.02 µg/dL during the FRW Period III [95% CI, 0.79, 0.95]; p<.001. The percentage of BLLs ≥5.0 μg/dL decreased from Period I (10.6%) to Period II (3.3%) [95% CI, 5.7, 8.8]; p<.001 and from Period I to Period III (3.9%) [95% CI, 5.0, 8.2]; p=.002. The 0.6% increase from Period II to Period III was not statistically significant [95% CI, -1.9, 0.57]; p=.30. Conclusion: Analyses of GM and percentages ≥5.0 μg/dL of BLLs do not support the occurrence of a global increase in BLLs in young children of Flint during the entire 18-month period of FRW exposure.

Scale Formation Under Blended Phosphate Treatment for a Utility With Lead Pipes

US corrosion control practice often assumes that the orthophosphate component of blended phosphate corrosion inhibitors causes the formation of low-solubility lead-orthophosphate solids that control lead release into drinking water. This study identified the solids that formed on the interior surface of a lead service line and a galvanized steel pipe excavated from a system using a proprietary blended phosphate chemical. The scale was analyzed by X-ray diffraction, X-ray fluorescence, and scanning electron microscopy/energy dispersive spectroscopy. Instead of crystalline lead-orthophosphate solids, a porous amorphous layer rich in aluminum, calcium, phosphorus, and lead was observed at the lead pipe scale-water interface. Thus, the mechanism inhibiting lead release into the water was not a thermodynamically predictable passivating lead-orthophosphate scale, but rather an amorphous barrier deposit that was possibly vulnerable to disturbances. Galvanized pipe scales showed relatively crystalline iron and zinc compounds, with additional surface deposition of aluminum, phosphorus, calcium, and lead.