Health and economic impact of nitrate pollution in drinking water: a Wisconsin case study

Direct potable reuse and birth defects prevalence in Texas: An augmented synthetic control method analysis of data from a population-based birth defects registry

Background

Direct potable reuse (DPR) involves adding purified wastewater that has not passed through an environmental buffer into a water distribution system. DPR may help address water shortages and is approved or is under consideration as a source of drinking water for several water-stressed population centers in the United States, however, there are no studies of health outcomes in populations who receive DPR drinking water. Our objective was to determine whether the introduction of DPR for certain public water systems in Texas was associated with changes in birth defect prevalence.

Methods

We obtained data on maternal characteristics for all live births and birth defects cases regardless of pregnancy outcome in Texas from 2003 to 2017 from the Texas Birth Defects Registry and birth and fetal death records. The ridge augmented synthetic control method was used to model changes in birth defect prevalence (per 10,000 live births) following the adoption of DPR by four Texas counties in mid-2013, with county-level data on maternal age, percent women without a high school diploma, percent who identified as Hispanic/Latina or non-Hispanic/Latina Black, and rural-urban continuum code as covariates.

Results

There were nonstatistically significant increases in prevalence of all birth defects collectively (average treatment effect in the treated = 53.6) and congenital heart disease (average treatment effect in the treated = 287.3) since June 2013. The estimated prevalence of neural tube defects was unchanged.

Conclusions

We estimated nonstatistically significant increases in birth defect prevalence following the implementation of DPR in four West Texas counties. Further research is warranted to inform water policy decisions.

Health-economic valuation of lowering nitrate standards in drinking water related to colorectal cancer in Denmark

Nitrate in drinking water is a contaminant which can affect human health and has been associated with an increased risk of, amongst other diseases, colorectal cancer. Based on epidemiologic data from Denmark on the association between drinking water nitrate and colorectal cancer, the health and economic consequences of lowering the standard of nitrate in drinking water from 50 mg/L to 9.25 mg/L and 3.87 mg/L, respectively are analyzed. The drinking water nitrate attributable number of cases was estimated using the risk in the exposed and unexposed population based on current nationwide exposure distributions. The analysis shows that a lower limit of 9.25 mg/L would decrease the annual number of colorectal cancer cases by 72 (95 % confidence interval: 34-114) and by an additional 55 (95 % CI: 10-100) for a stricter limit of 3.87 mg/L. The resulting avoided health-related costs are $179 million per year for the 9.25 mg/L nitrate limit and another $138 million per year for a further reduction to 3.87 mg/L nitrate. The new requirements would incur costs linked to either i) changes in land use management, ii) well reallocation or iii) use of treatment technologies. The additional costs are estimated to $0.03-1.84 per m3 abstracted water from public water companies, which together with costs for owners of private wells, will result in an average additional cost of $9 and $6 million per year for the two levels. The economic health benefits are higher than the costs for both limits with net gains of $170 million (9.25 mg/L) and additionally $132 million (3.87 mg/L) a year. Even in a worst-case scenario (lowest health-related benefits and highest mitigation costs), there is a likely economic gain for society from lowering the limit to 9.25 mg/L, but this might not be the case for the lower limit of 3.87 mg/L.

Burden of disease from contaminated drinking water in countries with high access to safely managed water: A systematic review

The vast majority of residents of high-income countries (≥90%) reportedly have high access to safely managed drinking water. Owing perhaps to the widely held perception of near universal access to high-quality water services in these countries, the burden of waterborne disease in these contexts is understudied. This systematic review aimed to: identify population-scale estimates of waterborne disease in countries with high access to safely managed drinking water, compare methods to quantify disease burden, and identify gaps in available burden estimates. We conducted a systematic review of population-scale disease burden estimates attributed to drinking water in countries where ≥90% of the population has access to safely managed drinking water per official United Nations monitoring. We identified 24 studies reporting estimates for disease burden attributable to microbial contaminants. Across these studies, the median burden of gastrointestinal illness risks attributed to drinking water was ∼2,720 annual cases per 100,000 population. Beyond exposure to infectious agents, we identified 10 studies reporting disease burden-predominantly, cancer risks-associated with chemical contaminants. Across these studies, the median excess cancer cases attributable to drinking water was 1.2 annual cancer cases per 100,000 population. These median estimates slightly exceed WHO-recommended normative targets for disease burden attributable to drinking water and these results highlight that there remains important preventable disease burden in these contexts, particularly among marginalized populations. However, the available literature was scant and limited in geographic scope, disease outcomes, range of microbial and chemical contaminants, and inclusion of subpopulations (rural, low-income communities; Indigenous or Aboriginal peoples; and populations marginalized due to discrimination by race, ethnicity, or socioeconomic status) that could most benefit from water infrastructure investments. Studies quantifying drinking water-associated disease burden in countries with reportedly high access to safe drinking water, focusing on specific subpopulations lacking access to safe water supplies and promoting environmental justice, are needed.

Fluoride and nitrate enrichment in coastal aquifers of the Eastern Province, Saudi Arabia: The influencing factors, toxicity, and human health risks

Fluoride and nitrate contamination of groundwater is a major environmental issue in the world's arid and semiarid regions. This issue is severe in both developed and developing countries. This study aimed at assessing the concentration levels, contamination mechanisms, toxicity, and human health risks of NO₃^- and F^- in the groundwater within the coastal aquifers of the eastern part of Saudi Arabia using a standard integrated approach. Most of the tested physicochemical properties of the groundwater exceeded their standard limits. The water quality index and synthetic pollution index evaluated the suitability of the groundwater and showed that all the samples have poor and unsuitable quality for drinking. The toxicity of F^- was estimated to be higher than NO₃^-. Also, the health risk assessment revealed higher risks due to F^- than NO₃^-. Younger populations had higher risks than elderly populations. For both F^- and NO₃^-, the order of health risk was Infants > Children > Adults. Most of the samples posed medium to high chronic risks due to F^- and NO₃^- ingestion. However, negligible health risks were obtained for potential dermal absorption of NO₃^-. Na-Cl and Ca-Mg-Cl water types predominate in the area. Pearson's correlation analysis, principal component analysis, regression models, and graphical plots were used to determine the possible sources of the water contaminants and their enrichment mechanisms. Geogenic and geochemical processes had greater impact he groundwater chemistry than anthropogenic activities. For the first time, these findings provide public knowledge on the overall water quality of the coastal aquifers and could help the inhabitants, water management authorities, and researchers to identify the groundwater sources that are most desirable for consumption and the human populations that are vulnerable to non-carcinogenic health risks.

Aerobic denitrifying bacterial-fungal consortium mediating nitrate removal: Dynamics, network patterns and interactions

In recent years, nitrogen removal by mixed microbial cultures has received increasing attention owing to cooperative metabolism. A natural bacterial-fungal consortium was isolated from mariculture, which exhibited an excellent aerobic denitrification capacity. Under aerobic conditions, nitrate removal and denitrification efficiencies were up to 100% and 44.27%, respectively. High-throughput sequencing and network analysis suggested that aerobic denitrification was potentially driven by the co-occurrence of the following bacterial and fungal genera: Vibrio, Fusarium, Gibberella, Meyerozyma, Exophiala and Pseudoalteromonas, with the dominance of Vibrio and Fusarium in bacterial and fungal communities, respectively. In addition, the isolated consortium had a high steady aerobic denitrification performance in our sub-culturing experiments. Our results provide new insights on the dynamics, network patterns and interactions of aerobic denitrifying microbial consortia with a high potential for new biotechnology applications.

Denitrification of nitrate in regeneration waste brine using hybrid cation exchanger supported nanoscale zero-valent iron with/without palladium nanoparticles

The Sustainable Development Goals require that reducing waste is a priority. This work described the application of an innovative zero-waste hybrid ion exchange nanotechnology that concurrently removed nitrate and induced denitrification to ammonia, with the ability to generate fertilizer for the agriculture sector from the recycled by-products. Herein, hybrid cation exchanger-supported zero-valent iron (Fe⁰), and bimetallic Fe⁰/Pd nanoparticles (HCIX-Fe⁰ and HCIX-Fe⁰/Pd) were synthesized and successfully validated for denitrification of nitrate in spent waste brine that contained nitrate. The kinetics of nitrate catalysis by both HCIX-Fe⁰ and HCIX-Fe⁰/Pd were compared and presented by six kinetic models, namely, zero-order, pseudo first- and second-order reaction, pseudo first- and second-order adsorption, and Elovich. HCIX-Fe⁰/Pd displayed a higher kinetic value than HCIX-Fe⁰, with k₁ of 0.0019 and 0.0026 min^-1, respectively. Nitrate was predominantly catalysed to NH₄⁺ at a ratio of ammonia to other nitrogen compounds of around 80:20. Although HCIX-Fe⁰/Pd showed slightly better (14%) kinetic results, it was determined as unfavourable for real-life application due to low selectivity toward N₂ gas and the need to use H₂ gas. Based on practicability, the HCIX-Fe⁰ was further validated. The effect of salt (using NaCl) and the role of initial pH conditions were optimized and discussed. The recovery of nitrate removal was also calculated, and a recovery range of 91.42-99.14% was obtained for three consecutive runs. The sustainable, novel, zero waste hybrid ion exchange nanotechnology using the combination of two fixed-bed columns containing nitrate-selective resin for nitrate removal and novel HCIX-Fe⁰ for nitrate reduction to NH₄⁺ may be a promising sustainable solution toward the goal of discharging zero nitrate waste to the environment.

Nitrate transport velocity data in the global unsaturated zones

Nitrate pollution in groundwater, which is an international problem, threatens human health and the environment. It could take decades for nitrate to transport in the groundwater system. When understanding the impacts of this nitrate legacy on water quality, the nitrate transport velocity (v_N) in the unsaturated zone (USZ) is of great significance. Although some local USZ v_N data measured or simulated are available, there has been no such a dataset at the global scale. Here, we present a Global-scale unsaturated zone Nitrate transport Velocity dataset (GNV) generated from a Nitrate Time Bomb (NTB) model using global permeability and porosity and global average annual groundwater recharge data. To evaluate GNV, a baseline dataset of USZ v_N was created using locally measured data and global lithological data. The results show that 94.50% of GNV match the baseline USZ v_N dataset. This dataset will largely contribute to research advancement in the nitrate legacy in the groundwater system, provide evidence for managing nitrate water pollution, and promote international and interdisciplinary collaborations.

Thyroid cancer incidence trend and association with obesity, physical activity in the United States

BACKGROUND

State-level racial/ethnic and age differences and the temporal trend of thyroid cancer (TC) incidence in the USA remain unknown. Our research purposes include: Characterizing state-level temporal variation in TC incidence; examining the disparities of TC incidence by state-level race/ethnicity and age; performing an ecological correlation between TC incidence and obesity/physical activity.

METHODS

TC incidence data during 2000-2017 were extracted from the United States cancer statistics. Using joinpoint regression to evaluate TC incidence trends. Annual percent change (APC), average APC (AAPC) and incidence rates were calculated. The obesity prevalence and physical activity level at the state-level were extracted from Behavioral Risk Factor Surveillance System, and the association between state-level AAPC of TC and obesity/physical activity was tested by Pearson correlation coefficient.

RESULTS

We found that the TC incidence had shown an overall downward trend in recent years, but 10 states continued increasing. There were significant differences in state-level race/ethnicity (non-Hispanic Whites as a reference) and age group (45-59 age group as a reference) incidence: Incidence Rate Ratio (IRR) was 0.4-1.2 for non-Hispanic Blacks, 0.7-1.6 for non-Hispanic Asian and Pacific Islanders, 0.4-1.2 for non-Hispanic American Indians/Alaskan Natives, and 0.5-1.3 for Hispanics. High IRR in young people were distributed in northern USA, while in older people were distributed in south. The state-level obesity/physical activity level and AAPC had a weak correlation (r = 0.34, P = 0.016) and inverse weak correlation (r = -0.29, P = 0.037), respectively. The AAPC of states with a consistent increasing trend had an extremely strong correlation with obesity prevalence (r = 0.80, p = 0.006), and an inverse strong correlation with physical activity level (r = -0.65, P = 0.04).

CONCLUSIONS

Thyroid cancer incidence in 10 states continued increasing. State-level variation in race/ethnicity and age group incidence were found. Lifestyle and environmental factors may interfere with the incidence trend of TC in the USA.