Point-of-use Water Treatment for Private Wells in North Carolina: Risks and Solutions for Lead, Per- and Polyfluoroalkyl Substances (PFASs), and Microbial Contaminants

Almost 50 million people across the United States and Canada rely on privately-owned wells for their domestic water needs. Private well users are legally responsible for maintaining their own water quality as no enforceable drinking water standards nor monitoring and treatment requirements exist for private wells as they do for public water systems. As a result, private well users are potentially exposed to a range of chemical and microbial contaminants through their drinking water. Point-of-use (POU) water treatment represents one potential solution to reduce harmful exposures through well water, but well users frequently do not adopt any household treatment even after the results of a water test indicate some form of contamination. Additionally, the effectiveness of consumer POU treatment products for removing certain contaminants from private well water, including lead and per- and polyfluoroalkyl substances (PFASs), is largely unknown, as very few studies have tested their performance over time in household settings. This research thus aims to advance knowledge around POU water treatment for private well water to reduce the barriers to these solutions for well users. An under-sink activated carbon block POU filter was installed in the homes of 18 well users across North Carolina and tested monthly for eight months for metals, PFASs, and microbial indicator organisms. Filters removed 98% of all influent lead on average for the entire study duration and significantly improved the safety and effectiveness of faucet flushing, reducing levels at the tap to below the American Academy of Pediatrics recommendation of 1 µg/L of lead in drinking water. Additionally, filters consistently removed 97-99% of all influent PFASs, including emerging short-chain perfluoroalkyl ether acids, even up to two months beyond the manufacturer recommended lifetime of the device. Filters did not result in increased microbial risk of drinking water at the tap under normal conditions of use, but the results emphasized the need for additional well protections and maintenance to ensure the microbial safety of private well water, regardless of the decision to implement POU treatment. Finally, the experiences of participants in this study highlighted the need for strengthened well outreach and support programs that provide technical assistance and financial support to private well users around POU treatment in addition to well testing. The results of this study may thus be used by state and local health departments to provide evidence-based recommendations around the use of POU filters for private well users that may significantly reduce lead and PFAS exposures among this population.Doctor of Philosoph

Personal Internalization of a Confederate Monument Removal Event Associated with Increased Depression, Anxiety, and Stress Among University Students

This study sought to determine the association between racialized events relating to the removal of a Confederate monument and mental health outcomes among students at a Southern state-university in the United States. After the removal of a Confederate monument located on the university’s campus, racialized protests and violent clashes with police forces ensued. To assess the impact of these events on student mental health outcomes, a cross-sectional survey was disseminated to 10,000 current students. Student mental health was measured using the 21-item Depression, Anxiety, and Stress Scale (DASS). The key exposure, personal internalization of the event, was measured using the seven-question Centrality of Event Scale (CES) and was defined as the perceived importance of the racialized event for the students’ identity and life story. Student demographic information including race, ethnicity, gender, age, and minority status was collected anonymously. Logistic regression was used to compare mental health outcomes of students with high versus low personal internalization of the event, with an interaction term included to capture if the relationship was stronger among students who identified as a minority. After adjusting for minority status, higher internalization of the event was associated with adverse mental health outcomes (OR = 1.96 [95%CI, 1.18-3.25]). However, there was insufficient evidence to determine that minority status modified the results, which may be due to limited power. Overall, these findings demonstrate that increased internalization of the removal event was associated with adverse mental health outcomes among students during the first two weeks of the academic semester, underscoring the importance of state and university official’s consideration of the mental health implications of racial tensions arising from Confederate monument removal events for diverse student populations and strategies for mitigating these outcomes

Eliminating lead exposure from drinking water—A global call to action

Each year, approximately 900,000 people die from exposure to lead [1]. But the full impacts of lead exposure are far more insidious. Lead is a potent neurotoxin that impairs brain function and irreversibly harms children’s cognitive development. Any exposure to lead can be damaging. Recent studies estimate that 800 million children globally (approximately 1 in 3) have blood lead concentrations above 5 micrograms per deciliter and that lead exposure may be responsible for 30% of all intellectual disabilities of unknown origin [2, 3]. Lead exposure increases disease burden, estimated at over 21 million disability-adjusted life years (DALYs) yearly, primarily due to cardiovascular diseases and mental disorders. This disease burden attributed to lead has increased globally since 1990, because of population growth and aging [4]. Additional research has shown evidence of a direct dose-response relationship between children’s blood lead levels and reductions in IQ which decreases lifetime earnings [5, 6]. This makes lead a public health threat and a key environmental risk factor that exacerbates long-term inequalities affecting especially marginalized groups. Important sources of exposure include batteries, paint, food containers, drinking water systems, and leaded gasoline (now banned in all countries)

Telemediations

Postprin

Under-Sink Activated Carbon Water Filters Effectively Remove Lead from Private Well Water for over Six Months

Children who rely on private well water in the United States have been shown to be at greater risk of having elevated blood lead levels. Evidence-based solutions are needed to prevent drinking water lead exposure among private well users, but minimal data are available regarding the real-world effectiveness of available interventions like point-of-use water treatment for well water. In this study, under-sink activated carbon block water filters were tested for lead and other heavy metals removal in an eight-month longitudinal study in 17 homes relying on private wells. The device removed 98% of all influent lead for the entirety of the study, with all effluent lead levels less than 1 µg/L. Profile sampling in a subset of homes showed that the faucet fixture is a significant source of lead leaching where well water is corrosive. Flushing alone was not capable of reducing first-draw lead to levels below 1 µg/L, but the under-sink filter was found to increase the safety and effectiveness of faucet flushing. The results of this study can be used by individual well users and policymakers alike to improve decision-making around the use of under-sink point-of-use devices to prevent disproportionate lead exposures among private well users

Removal of N-Nitrosodimethylamine and Other Disinfection By-Product Precursors from Tertiary Wastewater Effluent by Activated Carbon

Organic constituents at the low to sub-microgram per liter level derived from wastewater effluents represent precursors to previously undetected disinfection by-products (DBPs) in drinking water utilities. N-nitrosodimethylamine (NDMA) is an emerging DBP of particular concern due to its suspected genotoxicity and carcinogenicity an order of magnitude greater than currently regulated DBPs. Granular activated carbon (GAC) has been shown to be a potential control technology for removing NDMA precursors from wastewater effluent, but adsorption behavior of specific precursor material is still poorly understood. The goal of this research is to expand knowledge of the GAC adsorption behavior of NDMA and other DBP precursors in wastewater effluent, including understanding the effect of different activated carbon types, the effect of varying GAC column Empty Bed Contact Time (EBCT), the effect of source water blending on NDMA precursor sorption, and the breakthrough of NDMA precursors relative to trihalomethane, haloacetic acid, and haloacetonitrile precursors. Lignite-based and wood-based activated carbon were found to remove NDMA precursors better than coconut-shell and bituminous carbons, presumably due to larger mesopore volumes. NDMA precursors are thought to be larger molecular weight compounds or behave in water such that adsorption occurs in the mesopore region. A distinct non-adsorbable fraction in powdered activated carbon batch tests suggests a range of different precursor compounds. In Rapid Small-Scale Column Tests (RSSCTs), a simulated 20-minute bench-scale EBCT performed better than a 10-minute column, thus longer EBCTs are suggested when optimizing GAC control for NDMA precursors in wastewater. NDMA precursors were also found to adsorb independently of bulk organic matter and other DBP precursors, suggesting its precursors are distinct from currently regulated and other nitrogenous DBPs. As a result, Overall Fluorescence Intensity was proposed as a possible surrogate for NDMA precursors due to its similar adsorption behavior in RSSCTs using blended influent waters. Evidence is also presented for considering NDMA precursors as similar to micropollutants due to rapid sorption in batch testing distinct from DOM, and diminished impacts of influent concentrations on fractional RSSCT breakthrough

Effect of Community Water Service on Lead in Drinking Water in an Environmental Justice Community

Multiple recent studies have found elevated lead (Pb) concentrations in tap water in U.S. homes relying on unregulated private wells. The main Pb source is dissolution from household plumbing, fixtures, and well components. Here, we leverage a natural experiment and citizen science approach to evaluate how extending community water service to an environmental justice community relying on private wells affects Pb in household water. We analyzed Pb in 260 first-draw kitchen tap water samples collected by individual homeowners over a 5-month period in residences that did and did not connect to the community system. Before the community water system was extended, 25% of homes had Pb > 15 μg/L (the U.S. regulatory action level for community water systems) in first-draw water samples. Pb was significantly correlated with nickel (ρ = 0.61), zinc (ρ = 0.50), and copper (ρ = 0.40), suggesting that corrosion of brass fittings and fixtures is the main Pb source. Among homes that connected to the community system, Pb decreased rapidly and was sustained at levels well below 15 μg/L over the study period. Overall, connecting to the municipal water supply was associated with a 92.5% decrease in first-draw tap water Pb

Evaluating Activated Carbon Adsorption of Dissolved Organic Matter and Micropollutants Using Fluorescence Spectroscopy

Dissolved organic matter (DOM) negatively impacts granular activated carbon (GAC) adsorption of micropollutants and is a disinfection byproduct precursor. DOM from surface waters, wastewater effluent, and 1 kDa size fractions were adsorbed by GAC and characterized using fluorescence spectroscopy, UV-absorption, and size exclusion chromatography (SEC). Fluorescing DOM was preferentially adsorbed relative to UV-absorbing DOM. Humic-like fluorescence (peaks A and C) was selectively adsorbed relative to polyphenol-like fluorescence (peaks T and B) potentially due to size exclusion effects. In the surface waters and size fractions, peak C was preferentially removed relative to peak A, whereas the reverse was found in wastewater effluent, indicating that humic-like fluorescence is associated with different compounds depending on DOM source. Based on specific UV-absorption (SUVA), aromatic DOM was preferentially adsorbed. The fluorescence index (FI), if interpreted as an indicator of aromaticity, indicated the opposite but exhibited a strong relationship with average molecular weight, suggesting that FI might be a better indicator of DOM size than aromaticity. The influence of DOM intermolecular interactions on adsorption were minimal based on SEC analysis. Fluorescence parameters captured the impact of DOM size on the fouling of 2-methylisoborneol and warfarin adsorption and correlated with direct competition and pore blockage indicators