Estimating perchlorate exposure from food and tap water based on U.S. biomonitoring and occurrence data

Journal of Exposure Science & Environmental Epidemiology (Springer) | June 23rd, 2010

Human biomonitoring data show that exposure to perchlorate is widespread in the United States. The predominant source of intake is food, whereas drinking water is

Human biomonitoring data show that exposure to perchlorate is widespread in the United States. The predominant source of intake is food, whereas drinking water is a less frequent and far smaller contributor. We used spot urine samples for over 2700 subjects and estimated 24 h intake using new creatinine adjustment equations. Merging data from surveys of national health (NHANES) with drinking water monitoring (UCMR), we categorized survey participants according to their potential exposure through drinking water or food. By subtracting daily food doses of perchlorate from the oral reference dose (RfD), we derive an allowances for perchlorate in tap water for several populations. The calculated mean food perchlorate dose in the United States was 0.081 μg/kg/day compared to 0.101 μg/kg/day for those who also had a potential drinking water component. The calculated 95th percentile doses, typically falling between 0.2 and 0.4 μg/kg/day, were well below the RfD (0.7 μg/kg/day) in all populations analyzed. Children aged 6–11 years had the highest mean perchlorate doses in food (0.147 μg/kg/day), with an additional water contribution of only 0.003 μg/kg/day representing just 2% of exposure. Pregnant women had a mean food dose of 0.093 vs 0.071 μg/kg/day for all women of reproductive age. At the 95th percentile intake for both the total population and women of child-bearing age (15–44), the perchlorate contribution from food was 86% and from drinking water 14% (respectively, 30% and 5% of the RfD). At the mean for the same groups, the food to water contribution ratio is approximately 80:20. We calculate that an average 66 kg pregnant woman consuming a 90th percentile food dose (0.198 μg/kg/day) could also drink the 90th percentile of community water for pregnant women (0.033 l/kg/day) containing 15 μg/l perchlorate without exceeding the 0.7 μg/kg/day reference dose.

Evaluating the hidden costs of drinking water treatment technologies

Nature Portfolio (Springer Nature) | April 3rd, 2023

Drinking water treatment technologies are largely evaluated on the basis of metrics such as contaminant removal efficiency, capital costs and health impacts. However, the

Drinking water treatment technologies are largely evaluated on the basis of metrics such as contaminant removal efficiency, capital costs and health impacts. However, the potential for safe water technologies to lead to positive health outcomes depends greatly on user satisfaction, consistent and sustained operation, and financial viability. In this Perspective, we argue for the importance for engineering, public health and economics researchers to assess the ‘hidden’ costs of drinking water treatment technologies, including affordability, labour burden, user acceptance, and the (often) gendered nature of these. Neglecting these factors results in an underestimation of the full costs of drinking water treatment technologies and an overestimation of the potential for treatment options that require substantial behaviour change and time to succeed. Here we present a set of user-centric evaluation criteria for water service providers, practitioners, governments and other stakeholders to consider when deciding which drinking water treatment technologies to implement, scale up or take to market.

Factors Affecting Public-Supply-Well Vulnerability to Contamination: Understanding Observed Water Quality and Anticipating Future Water Quality

U.S. Geological Survey (USGS) | May 14th, 2013

As part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, a study was conducted from 2001 to 2011 to shed light on factors that affect the

As part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, a study was conducted from 2001 to 2011 to shed light on factors that affect the vulnerability of water from public-supply wells to contamination (referred to hereafter as “public-supply-well vulnerability”). The study was designed as a follow-up to earlier NAWQA studies that found mixtures of contaminants at low concentrations in groundwater near the water table in urban areas across the Nation and, less frequently, in deeper groundwater typically used for public supply. Beside the factors affecting public-supply-well vulnerability to contamination, this circular describes measures that can be used to determine which factor (or factors) plays a dominant role at an individual public-supply well. Case-study examples are used throughout to show how such information can be used to improve water quality. In general, the vulnerability of the water from public-supply wells to contamination is a function of contaminant input within the area that contributes water to a well, the mobility and persistence of a contaminant once released to the groundwater, and the ease of groundwater and contaminant movement from the point of recharge to the open interval of a well. The following measures described in this circular are particularly useful for indicating which contaminants in an aquifer might reach an individual public-supply well and when, how, and at what concentration they might arrive: Sources of recharge—Information on the sources of recharge for a well provides insight into contaminants that might enter the aquifer with the recharge water and potentially reach the well. Geochemical conditions—Information on the geochemical conditions encountered by groundwater traveling to a well provides insight into contaminants that might persist in the water all the way to the well. Groundwater-age mixtures—Information on the ages of the different waters that mix in a well provides insight into the time lag between contaminant input at the water table and contaminant arrival at the well. It also provides insight into the potential for in-well dilution of contaminated water by unaffected groundwater of a different age that simultaneously enters the well. Preferential flow pathways—pathways that provide little resistance to flow—can influence how all other factors affect public-supply-well vulnerability to contamination. For example, preferential flow pathways can influence whether a contaminant source is physically linked to a well, whether contaminant concentrations are substantially altered before contaminated groundwater reaches a well, and whether contaminated groundwater can arrive at a well within a timeframe of concern to the well owner. Methods for recognizing the influence of preferential flow pathways on the quality of water from a public-supply well are presented in this circular and can provide opportunities to prevent or mitigate the deterioration of a water supply. Knowing what water-quality variables to measure, what spatial and temporal scales on which to measure them, and how to interpret the resulting data makes it possible for samples from public-supply wells to provide a broad window into a well’s past and present water quality—and possibly future water quality. Such insight can enable resource managers to prioritize actions for sustaining a high-quality groundwater source of drinking water.

Final Environmental Impact Report for Adoption of a Regulation for the Hexavalent Chromium Maximum Contaminant Level

California State Water Resources Control Board (SWRCB) | April 17th, 2024

As the lead agency in accordance with sections 15089 and 15132 of the California Environmental Quality Act (CEQA) Guidelines (Cal. Code Regs., tit. 14, § 15000 et seq.),

As the lead agency in accordance with sections 15089 and 15132 of the California Environmental Quality Act (CEQA) Guidelines (Cal. Code Regs., tit. 14, § 15000 et seq.), this document is the Final Environmental Impact Report (Final EIR) for the adoption of statewide regulations setting the maximum contaminant level (MCL) for hexavalent chromium (Proposed Regulations). The Proposed Regulations include a maximum contaminant level (MCL) of 10 μg/L for hexavalent chromium. (Cal. Code Regs. tit. 22, § 64431 Table 64431-A.) The Proposed Regulations also include a compliance schedule based on public water system size, by adding subdivision (p) and Table 64432-B to section 64432 of title 22 of the California Code of Regulations, identifies a detection limit for purposes of reporting, sets monitoring and reporting requirements and public notice requirements for violations of the MCL, and establishes the Best Available Technologies (BAT) for treating hexavalent chromium in drinking water. California State Water Resources Control Board (SWRCB) Chrom VI MCL rulemaking chronology.

Fourth Five Year Review Report for the San Gabriel Valley Area 2 Superfund Site, Los Angeles, California

U.S. Environmental Protection Agency (EPA) | September 15th, 2022

This is the fourth Five-Year Review of the San Gabriel Valley Area 2 (Site) located in the San Gabriel Valley in Los Angeles County, California. The purpose of this Five-

This is the fourth Five-Year Review of the San Gabriel Valley Area 2 (Site) located in the San Gabriel Valley in Los Angeles County, California. The purpose of this Five-Year Review is to review information to determine if the remedy is and will continue to be protective of human health and the environment. The Site addresses approximately 10 square miles of groundwater contamination in eastern Los Angeles County within the San Gabriel Valley. Groundwater contamination is believed to result from the cumulative impact of decades of improper chemical handling and disposal practices at numerous industrial operations in the Valley. The Site contamination originates at current and former industrial facilities in and near Azusa, California and extends to the southwest through portions of the cities of Irwindale, Baldwin Park, West Covina, and Industry. The most prevalent contaminants in groundwater are trichloroethylene, tetrachloroethylene, carbon tetrachloride, perchlorate, n-nitrosodimethylamine (NDMA), and 1,4-dioxane.

Gauging climate preparedness to inform adaptation needs: local level adaptation in drinking water quality in CA, USA

Climatic Change (Springer) | December 23rd, 2013

Understanding resource managers’ perceptions of climate change, analytic capacity, and current adaptation activities can provide insight into what can help support ada

Understanding resource managers’ perceptions of climate change, analytic capacity, and current adaptation activities can provide insight into what can help support adaptation processes at the local level. In California, where a major drought currently demonstrates some of the hardships that could be regularly encountered under a changing climate, we present results from a survey of drinking water utilities about the perceived threat, analytic capacity, and adaptation actions related to maintaining water quality in the face of climate change. Among surveyed utilities (n = 259), awareness is high in regard to climate change occurring and its potential impacts on water quality globally, but perceived risk is lower with regard to climate impacts on local drinking water quality. Just over half of surveyed utilities report at least some adaptation activity to date. The top three variables that most strongly correlated with reported adaptation action were (1) perceived risk on global and local water quality, (2) surface water reliance, and (3) provision of other services beyond drinking water. Other tested variables significantly correlated with reported adaptation action were (4) degree of impact from the current drought and (5) communication with climate change experts. Findings highlight that smaller groundwater-reliant utilities may need the most assistance to initiate climate adaptation processes. Trusted information sources most frequently used across respondents were state government agencies, followed by colleagues in the same utilities. The finding that frequently used sources of information are similar across utilities presents a promising opportunity for training and disseminating climate information to assist those systems needing the most support.

Geologic Influences on the Quality of Groundwater Used for Domestic Supply in the Northern Sierra Nevada Foothills

U.S. Geological Survey (USGS) | May 25th, 2021

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the U.S. Geological Survey, created the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) to assess the quality of groundwater used for domestic supply throughout the state and determine regional vulnerabilities to drinking-water resources. Many rural households in the northern Sierra Nevada foothills (hereafter referred to as “the foothills”) use domestic wells that pump water from fractured-bedrock aquifers. In the foothills, complicated and varied regional bedrock geology can cause substantial variation in groundwater chemistry and quality over relatively short distances. This factsheet presents findings from the GAMA-PBP assessment that highlight influences of geologic factors on groundwater quality in the foothills.

Groundwater Management Principles and Strategies to Monitor, Analyze and Minimize Impacts to Drinking Water Wells: A Framework for State Action to Support Drought Resilient Communities

California Department of Water Resources (DWR) | December 15th, 2021

This framework was developed in response to support drinking water access for groundwater-dependent communities.

This framework was developed in response to support drinking water access for groundwater-dependent communities.

Groundwater Quality in the Sacramento Metropolitan Shallow Aquifer, California

U.S. Geological Survey (USGS) | May 2nd, 2019

The Sacramento metropolitan (SacMetro) study unit covers approximately 3,250 square kilometers of the Central Valley along the eastern edge of the northern and southern e

The Sacramento metropolitan (SacMetro) study unit covers approximately 3,250 square kilometers of the Central Valley along the eastern edge of the northern and southern ends of the San Joaquin and Sacramento Valleys, respectively. Groundwater withdrawals supply a significant portion of the water-resource needs of the region. In the southern portion of the study unit, groundwater accounts for nearly 90 percent of water demand in the area (South Area Water Council, 2011).  Groundwater sampled in the SacMetro study unit comes from alluvial aquifers primarily composed of sediments derived from the Sierra Nevada Mountains to the east. Recharge to the groundwater system is primarily from the streams draining the Sierra Nevada, and from precipitation and infiltration of applied irrigation water (California Department of Water Resources, 2003). The public-supply aquifer system assessments of this area in 2005 found elevated concentrations of inorganic constituents including arsenic, iron, and manganese as well as of solvents in some wells (Bennett and others, 2010; 2011).  This study was designed to provide a statistically representative assessment of the quality of groundwater resources used for domestic drinking water in the SacMetro study unit. A complete listing of what was measured, including the sampling results, are presented in Bennett and others, 2019. A total of 49 wells were sampled between July 2017 and November 2017 (Bennett and others, 2019). The wells in the study were 32–160 meters deep, and water levels were 1–62 meters below land surface. 

Groundwater Quality in the San Fernando–San Gabriel Groundwater Basins, California

U.S. Geological Survey (USGS) | March 31st, 2012