Arsenic Maximum Contaminant Level Research Articles (Page 1)

Inorganic arsenic is associated with adverse birth outcomes, but evidence is limited for public water concentrations (modifiable by federal regulatory action) in US populations. To evaluate the association between prenatal public water arsenic exposure below the federal regulatory standard of 10 μg/L and birth outcomes in the US. This cohort study analyzed observational pregnancy cohort data from the Environmental Influences on Child Health Outcomes (ECHO) Cohort for birthing parent-infant dyads from 35 pregnancy cohort sites. Infants were born between 2005 and 2020. The data were analyzed between 2024 and 2025. Individual, time-weighted, mean prenatal public water arsenic exposures were estimated by joining Zip Code Tabulation Area-level public water arsenic concentrations with monthly residential history data during pregnancy. Adjusted risk ratios (RRs) of preterm birth, low birth weight, and small for gestational age were evaluated. Adjusted RRs, mean differences in birth weight-for-gestational age z score and birth weight, and the geometric mean ratio of gestational age at birth were calculated via cubic splines, per 1 μg/L higher prenatal water arsenic, and across policy-relevant categories of exposure. The cohort comprised 13 998 birthing parents (mean [SD] age, 30.8 [5.6] years) of whom 4.5% were of American Indian, Alaska Native, Native Hawaiian, or Pacific Islander; 7.2% Asian; 12.4% Black; 56.1% White; 4.2% multiple races; and 8.5% another race and 28.1% were of Hispanic/Latino and 70.4% non-Hispanic/Latino ethnicity. Prenatal public water arsenic ranged from less than 0.35 to 37.28 μg/L. In spline models, prenatal public water arsenic was associated with a higher risk of low birth weight, lower birth weight, and lower birth weight-for-gestational age z score, although effect estimates lacked precision. The RR of low birth weight per 1 μg/L higher prenatal water arsenic was higher among Black (1.02; 95% CI, 1.01-1.03), Hispanic/Latino (1.07; 95% CI 1.02-l.12), and White (1.04; 95% CI, 102-1.06) birthing parents, and the RR for preterm birth was higher among Hispanic/Latino birthing parents (1.05; 95% CI, 1.01-1.09). The mean difference of birth weight and birth weight-for-gestational age z score per 1 μg/L higher prenatal water arsenic was more pronounced among White birthing parents (-10 g [95% CI, -17 to -3 g]; -0.02 SDs [95% CI -0.03 to -0.01 SDs]). No evidence that prenatal public water arsenic mediated the association between birthing parent race and ethnicity and adverse birth outcomes was observed. In this cohort study of birthing parent-infant dyads across the US, arsenic measured in public water systems was associated with birth outcomes at levels below the current US Environmental Protection Agency's maximum contaminant level. The findings suggest that further reducing the maximum contaminant level for arsenic may decrease the number of infants with low birth weight in the US.

Arsenic in drinking water poses a threat to public health world-wide. In March 2001, the EPA revised the maximum contaminant level (MCL) for arsenic in drinking water downward from 50 µg/L to 10 µg/L and required all U.S. small community water systems (CWSs) and non-community water systems (NCWSs) to comply by 23 January 2006. Much of the financial burden associated with complying with and maintaining this new drinking water MCL was shouldered by local community governments. For example, the Walker River Paiute Tribe operated a CWS on the Walker River Paiute Indian Reservation that needed upgrading to meet the new arsenic MCL. In collaboration with the Walker River Paiute Tribe, we conducted a study to assess whether reducing the arsenic concentration in drinking water to meet the new MCL reduced the arsenic body burden in local community members who drank the water. Installing a drinking water treatment to remove arsenic dramatically reduced both the drinking water concentrations (to below the current EPA MCL of 10 µg/L) and the community members’ urinary concentrations of total As, AsIII, and AsV within a week of its full implementation. Additional assistance to small water systems to sustain new drinking water treatments may be warranted.

The United States Environmental Protection Agency (USEPA) regulates over 80 contaminants in community water systems (CWS), including those relevant to infant health outcomes. Multi-cohort analyses of the association between measured prenatal public water contaminant concentrations and infant health outcomes are sparse in the US. Our objectives were to (1) develop Zip Code Tabulation Area (ZCTA)-level CWS contaminant concentrations for participants in the Environmental Influences on Child Health Outcomes (ECHO) Cohort and (2) evaluate regional, seasonal, and sociodemographic inequities in contaminant concentrations at the ZCTA-level. The ECHO Cohort harmonizes data from over 69 extant pregnancy and pediatric cohorts across the US. We used CWS estimates derived from the USEPA's Six-Year Review 3 (2006-2011) to develop population-weighted, average concentrations for 10 contaminants across 7640 ZCTAs relevant to the ECHO Cohort. We evaluated contaminant distributions, exceedances of regulatory thresholds, and geometric mean ratios (with corresponding percent changes) associated with ZCTA sociodemographic characteristics via spatial lag linear regression models. We observed significant regional variability in contaminant concentrations across the US. ZCTAs were most likely to exceed the maximum contaminant level for arsenic (n = 100, 1.4%) and the health-protective threshold for total trihalomethanes (n = 3584, 64.0%). A 10% higher proportion of residents who were American Indian/Alaskan Native and Hispanic/Latino was associated with higher arsenic (11%, 95% CI: 7%, 15%; and 2%, 95% CI: 0%, 3%, respectively) and uranium (15%, 95% CI: 10%, 21%; and 9%, 95% CI: 6%, 12%, respectively) concentrations. Nationwide epidemiologic analyses evaluating the association between US community water system contaminant concentration estimates and associated adverse birth outcomes in cohort studies are sparse because public water contaminant concentration estimates that can be readily linked to participant addresses are not available. We developed Zip Code Tabulation Area (ZCTA)-level CWS contaminant concentrations that can be linked to participants in the Environmental Influences on Child Health Outcomes (ECHO) Cohort and evaluated regional, seasonal, and sociodemographic inequities in contaminant concentrations for these ZCTAs. Future epidemiologic studies can leverage these CWS exposure estimates in the ECHO Cohort to evaluate associations with relevant infant outcomes.

Numerous studies have found that rice and water, as components of the human diet, are potential pathways of arsenic exposure in humans. Due to the negative health effects linked with arsenic exposure, the quality of drinking water and rice samples must be continually monitored. This research was carried out in Baguio City, a small urban center in the Philippines. Following microwave digestion, arsenic in rice and water samples were determined using Atomic Absorption Spectrometry. The results showed that the National Food Authority (NFA) rice samples had arsenic content below the detection limit, indicating that this commercially available rice does not pose any health risk to Filipino consumers in terms of arsenic exposure. The arsenic value in other rice samples ranged from 8 μg/L to 27 μg/L, with the lowest and highest values found in organic brown rice and white rice varieties, respectively. Despite detectable arsenic in all 20 rice samples, all values were less than the maximum contaminant level (MCL) of 150 μg/L. Despite higher arsenic content in mixed rice than in white and organic colored rice, the mean differences are not significant, as proven by the Kruskal Wallis Test. All drinking water samples bought from water refilling stations had no detectable arsenic, while eight of the 18 (44%) of the spring water samples showed detectable amounts but are far below MCL of arsenic in drinking water. The findings suggest that the amount of arsenic in rice and spring water samples are too low to pose health risks over a short period of time.

ABSTRACT The World Health Organization (WHO) has classified arsenic as the most toxic chemical with carcinogenic effects and WHO has established a value of 10 μg/L arsenic as the maximum contaminant level for arsenic in potable water. High selectivity and high removal capacity are one of the most important factors when choosing an adsorbent. Hydrotalcite and hydrotalcite-like compounds have received much attention for the remediation of As-contaminated waters. The most interesting properties of layered double hydroxides (LDHs) include a large surface area and high anion exchange capacity. In this study, the importance of double-layered hydroxides, which has gained importance with the increasing environmental pollution recently, in removing oxyanion pollutants from water has been emphasized. This review article focuses on LDH synthesis and characterization techniques and arsenic removal potential using LDHs, as well as the safe consumability of water obtained after removal. In this review, various factors such as pH, dosage, and temperature that affect oxyanion adsorption on LDHs are discussed. The reusability of LDHs has been discussed. In addition, it has been investigated whether double-layer hydroxides (FeHT) could be used successfully in the removal of arsenic from polluted waters. It was also discussed whether the adsorbent used was safe for health.

Impact of lowering the US maximum contaminant level on arsenic exposure: Differences by race, region, and water arsenic in NHANES 2003–2014

Evaluation of a water arsenic filter in a participatory intervention to reduce arsenic exposure in American Indian communities: The Strong Heart Water Study

When the New Jersey Private Well Testing Act (PWTA) became effective in 2002, the maximum contaminant level (MCL) for arsenic in the United States was 50 μg/L. In 2006, the federal and New Jersey MCLs were lowered to 10 μg/L and 5 μg/L, respectively. To notify and provide free arsenic water testing for homeowners who had a PWTA arsenic result that passed for the MCL in 2006 or earlier but would exceed under the more health protective MCL enacted in 2006, which is still in effect as of this publication date. About 1200 homeowners with PWTA arsenic results between 5 μg/L and 50 μg/L were offered free arsenic water testing. More than 400 homeowners requested tests and 292 returned samples. New Jersey, United States. Homeowners with a passing PWTA arsenic result before 2006 that would have failed under the New Jersey arsenic MCL enacted in 2006. Return rate of testing kits; number of tests exceeding arsenic MCL; and participant survey results. Untreated well water samples (n = 279) were collected and 62.4% exceeded the New Jersey MCL. Treated well water samples (n = 102) were collected and 11.8% exceeded the current New Jersey MCL. In all, about 40% of drinking water samples from the tap, including those with or with no arsenic treatment, exceeded the New Jersey MCL. A survey of participants (n = 69) found that although many (67%) respondents reported that they at least had some idea that wells in their area are vulnerable to naturally occurring contaminants, such as arsenic, many (68%) reported that they had little or no idea that the New Jersey arsenic MCL had been lowered from 50 μg/L to 5 μg/L in 2006. This effort further illuminates the necessity and significance of public health outreach for private well water users, especially after drinking water standards change.

Background:In the United States, nationwide estimates of public drinking water arsenic exposure are not readily available. We used the U.S. Environmental Protection Agency’s (EPA) Six-Year Review contaminant occurrence data set to estimate public water arsenic exposure. We compared community water system (CWS) arsenic concentrations during 2006–2008 vs. after 2009–2011, the initial monitoring period for compliance with the U.S. EPA’s arsenic maximum contaminant level (MCL).Objective:Our objective was to characterize potential inequalities in CWS arsenic exposure over time and across sociodemographic subgroups.Methods:We estimated 3-y average arsenic concentrations for 36,406 CWSs (98%) and 2,740 counties (87%) and compared differences in means and quantiles of water arsenic (via quantile regression) between both 3-y periods for U.S. regions and sociodemographic subgroups. We assigned CWSs and counties MCL compliance categories (High if above the MCL; Low if below) for each 3-y period.Results:From 2006–2008 to 2009–2011, mean and 95th percentile CWS arsenic (in micrograms per liter) declined by 10.3% (95% CI: 6.5%, 14.1%) and 11.5% (8.3%, 14.8%) nationwide, by 11.4% (4.7%, 18.1%) and 16.3% (8.1%, 24.5%) for the Southwest, and by 36.8% (7.4%, 66.1%) and 26.5% (12.1%, 40.8%) for New England, respectively. CWSs in the High/High compliance category (not MCL compliant) were more likely in the Southwest (61.1%), served by groundwater (94.7%), serving smaller populations (mean 1,102 persons), and serving Hispanic communities (38.3%).Discussion:Larger absolute declines in CWS arsenic concentrations at higher water arsenic quantiles indicate declines are related to MCL implementation. CWSs reliant on groundwater, serving smaller populations, located in the Southwest, and serving Hispanic communities were more likely to continue exceeding the arsenic MCL, raising environmental justice concerns. These estimates of public drinking water arsenic exposure can enable further surveillance and epidemiologic research, including assessing whether differential declines in water arsenic exposure resulted in differential declines in arsenic-associated disease. https://doi.org/10.1289/EHP7313

Assessing chemical loading from streams in remote, difficult-to-access watersheds is challenging. The Grand Canyon area in northern Arizona, an international tourist destination and sacred place for many Native Americans, is characterized by broad plateaus divided by canyons as much as two-thousand meters deep and hosts some of the highest-grade uranium deposits in the U.S. From 2015–2018 major surface waters in Grand Canyon were monitored for select elements associated with breccia-pipe uranium deposits in the area, including uranium, arsenic, cadmium, and lead. Dissolved constituents in the Colorado River were monitored upstream (Lees Ferry), in the middle (Phantom Ranch), and downstream (Diamond Creek) of uranium mining areas. Concentrations of uranium, arsenic, cadmium, and lead at these main-stem sites varied little during the study period and were all well below human health and aquatic life benchmark criteria (30, 10, 5, and 15 μg/L maximum contaminant levels and 15, 150, 0.8, and 3.1 μg/L aquatic life criteria, respectively). Additionally, dissolved and sediment-bound constituents were monitored during a wide range of streamflow conditions at Little Colorado River, Kanab Creek, and Havasu Creek tributaries, whose watersheds have experienced different levels of uranium mining activities over time. Samples from the tributary sites contained ≤3.8 μg/L of dissolved cadmium and lead, and ≤17 μg/L of dissolved uranium. Dissolved arsenic also was mostly below human and aquatic life criteria at Little Colorado River and Kanab Creek; however, 63% of water samples from Havasu Creek were above the maximum contaminant level for arsenic. Arsenic in suspended sediment was greater than sediment quality guidelines in 9%, 35%, and 35% of samples from Little Colorado River, Kanab Creek, and Havasu Creek, respectively. At the concentrations observed during this study, tributaries contributed on average only about 0.12 μg/L of arsenic and 0.03 μg/L of uranium to the main-stem river. This study demonstrates how chemical loading from mined watersheds may be reliably assessed across a wide range of flow conditions in challenging locations.

This study uses a 2018 stated preference survey to elicit a willingness to pay (WTP) to reduce the cancer morbidity and mortality risk from arsenic exposure through drinking water. Respondents who use a public water supply are willing to pay $35.43 per month for the risk reduction associated with lowering the maximum allowable level of arsenic in drinking water from 10 to a hypothetical level of 3 ppb; households on private wells are willing to pay $29.19. Respondents from households with children were willing to pay significantly more than respondents from households without children. We derive values of a statistical life (VSL) of $4.61 million and $3.48 million per household member, respectively, in households using municipal or well water. Shortly after the initial release of these findings, New Hampshire became the second state to set a maximum allowable level for arsenic below the national limit of 10 ppb.

This study was designed to determine alterations in renal biomarkers, antioxidant profile, and histomorphology of renal tissue following subacute exposure to quinalphos alone or in conjunction with arsenic in rats. A total of 54 adult Wistar rats were randomly divided into nine groups of six rats each and were administered sub-lethal concentrations of quinalphos (1/100th and 1/10th of LD50) orally daily and arsenic (50 and 100ppb) in drinking water for 28days. Significantly (p < 0.05) decreased levels of antioxidant biomarkers in renal tissue, viz., total thiols, catalase, superoxide dismutase, glutathione peroxidase, glutathione-s-transferase, and glutathione reductase along with increased (p < 0.05) thiobarbituric acid reacting substance (TBRAS) levels indicated that significant oxidative damage to renal tissue occurred following repeated administrations of quinalphos at either dose levels or arsenic at the concentration of 100ppb when compared with the control rats. The alterations in the antioxidant parameters were observed to be more pronounced in co-administered groups as compared with either toxicant administered group. Similarly, activity of renal acetylcholinesterase was decreased after repeated exposure to quinalphos or arsenic, but inhibition was higher (up to 48%) in rat renal tissue co-exposed with quinalphos and arsenic at the higher concentration. These findings corroborated with the histopathological alterations in renal tissue of toxicant exposed rats. The altered plasma and tissue antioxidant biomarkers along with histopathological changes in the kidney at higher dose level of either toxicant indicate that renal tissue is significantly impacted by these toxicants, and these effects become more pronounced after their co-administration.

Arsenite removal from groundwater by aerated electrocoagulation reactor with Al ball electrodes: Human health risk assessment

Hydrogeological controls of arsenic and uranium dissolution into groundwater of the Pine Ridge Reservation, South Dakota

Arsenic contamination of groundwater in the Southern Gulf Coast Aquifer of Texas is a critical public health concern as much of the area is rural in nature with decentralized water supplies. Previous studies have pointed to volcanic deposits as the regional source of arsenic but no definitive or reliable predictors of arsenic maximum contaminant level (MCL) exceedance have been identified. In this study, we have studied the effect of various hydrogeochemical parameters as well as soil and land-use variables on arsenic MCL exceedance using logistic regression (LR) techniques. The LR models display good accuracy of 75% or higher but suffer from a high rate of false negatives, highlighting the challenges in capturing the spatial irregularities of arsenic in this region. Despite not displaying high statistical significance, pH appears to be an important variable in the LR models—its effect on arsenic exceedance is not clear and warrants further investigation. The results of the study also show that groundwater vanadium and fluoride are consistently the only significant variables in the models developed; the positive coefficients for both these elements indicates a common geogenic source for arsenic, fluoride and vanadium, corroborating the findings of earlier studies.

Trends in urinary arsenic among the U.S. population by drinking water source: Results from the National Health and Nutritional Examinations Survey 2003–2014

Global concern about arsenic in drinking water and its link to numerous diseases make translation of evidence-based research into national policy a priority. Delays in establishing a maximum contaminant level (MCL) to preserve health have increased the burden of disease and caused substantial and avoidable loss of life. The current Mexican MCL for arsenic in drinking water is 25μg/l (2.5 times higher than the World Health Organization (WHO) recommendation from 1993). Mexico's struggles to set its arsenic MCL offer a compelling example of shortcomings in environmental health policy. We explore factors that might facilitate policy change in Mexico: scientific evidence, risk communication and public access to information, economic and technological resources, and politics. To raise awareness of the health, societal, and economic implications of arsenic contamination of drinking water in Mexico, we suggest action steps for attaining environmental policy change and better protect population health.

Arsenic in private well water part 2 of 3: Who benefits the most from traditional testing promotion?

Abstract The Safe Drinking Water Act addresses harmful contaminants in drinking water by providing states the authority to monitor public water systems, notify the public of exceedances above allowable levels, and cite persistent violators. Violating water systems are subject to intense regulatory and public scrutiny. The response of contaminant levels to violation status has not been explored empirically. This paper addresses this relationship through an event study using data on arsenic and nitrate levels in California. I find that violation status has a significant positive effect on nitrate levels post-violation, but no effect on arsenic levels. I also examine the effect of the 2006 arsenic Maximum Contaminant Level revision, finding a discontinuity in contaminant levels at revision. These results suggest that while public disclosure may deter systems from violating, once they go into violation the Public Notification Rule is not effective at encouraging a return to compliance.

BackgroundInorganic arsenic exposure has been related to the risk of increased blood pressure based largely on cross-sectional studies conducted in highly exposed populations. Pregnancy is a period of particular vulnerability to environmental insults. However, little is known about the cardiovascular impacts of arsenic exposure during pregnancy.ObjectivesWe evaluated the association between prenatal arsenic exposure and maternal blood pressure over the course of pregnancy in a U.S. population.MethodsThe New Hampshire Birth Cohort Study is an ongoing prospective cohort study in which > 10% of participant household wells exceed the arsenic maximum contaminant level of 10 μg/L established by the U.S. EPA. Total urinary arsenic measured at 24–28 weeks gestation was measured and used as a biomarker of exposure during pregnancy in 514 pregnant women, 18–45 years of age, who used a private well in their household. Outcomes were repeated blood pressure measurements (systolic, diastolic, and pulse pressure) recorded during pregnancy.ResultsUsing linear mixed effects models, we estimated that, on average, each 5-μg/L increase in urinary arsenic was associated with a 0.15-mmHg (95% CI: 0.02, 0.29; p = 0.022) increase in systolic blood pressure per month and a 0.14-mmHg (95% CI: 0.02, 0.25; p = 0.021) increase in pulse pressure per month over the course of pregnancy.ConclusionsIn our U.S. cohort of pregnant women, arsenic exposure was associated with greater increases in blood pressure over the course of pregnancy. These findings may have important implications because even modest increases in blood pressure impact cardiovascular disease risk.CitationFarzan SF, Chen Y, Wu F, Jiang J, Liu M, Baker E, Korrick SA, Karagas MR. 2015. Blood pressure changes in relation to arsenic exposure in a U.S. pregnancy cohort. Environ Health Perspect 123:999–1006; http://dx.doi.org/10.1289/ehp.1408472