Health risk assessment of heavy metals and disinfection by-products in drinking water in megacities in China: A study based on age groups and Monte Carlo simulations

Non-carcinogenic health risks of fluoride exposure in minors based on national surveillance in China, 2014 and 2018

High fluoride concentrations in groundwater represent a substantial global public health concern. In China, over 70 million individuals suffer from drinking water fluorosis. This study reports national surveillance data in 2014 and 2018, dividing affected areas into six regions. The compliance rate for safe fluoride concentrations in drinking water improved by 13.1%. The data revealed a statistically significant difference in fluoride concentration between areas that underwent improvements and those that did not (Z = - 10.583, P < 0.001). The potential health risks for minors were evaluated, with hazard index (HI) values for minors exceeding 1, indicating the possibility of non-carcinogenic health risks associated with fluoride exposure. Furthermore, in certain regions, the non-carcinogenic health risks related to the current Chinese national standard for fluoride in drinking water (1.0 mg/L) for infants have surpassed the acceptable threshold. The implementation of improvement initiatives led to a reduction in the non-carcinogenic risk of fluoride exposure for minors, with odds ratios (95% CI) for infants, children, and teens were 0.369 (0.268, 0.509), 0.556 (0.452, 0.683), and 0.823 (0.740, 0.914), respectively. These findings can assist governmental agencies in formulating more effective policies for the protection of minors, particularly infants, from fluoride exposure.

Assessment of heavy metal contamination in groundwater of rural areas of Kurdistan Province Iran: A comprehensive study

This study focuses on the contamination of groundwater by heavy metals (HMs) in the Kurdistan Province of Iran, an area heavily reliant on these water resources, especially in rural regions. This research aimed to quantify the concentrations of 20 HMs in groundwater sources and assess the associated health risks, including both carcinogenic and non-carcinogenic effects, for different age groups. The study was conducted in 2024. We collected 155 groundwater samples from water resources of the villages in Kurdistan Province, west of Iran. The study encompassed comprehensive sampling of groundwater from various wells and springs throughout the province, which was subsequently subjected to thorough laboratory analysis utilizing Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) for the quantification of heavy metal (HM) concentrations. The highest concentrations of As, Co, Cu, and Mo were 7.90, 0.22, 2.48, and 1.68 μg/l, respectively. It was related to the cities of Qorveh, Sanandaj, Baneh, and Qorveh respectively. A Health Risk Assessment (HRA) was performed, indicating that, while the concentrations of most HMs were within the thresholds established by national and international standards, certain metals, such as arsenic and lithium, presented notable non-carcinogenic risks, especially to children. These metals were responsible for over 48 % of the cumulative hazard index (HI) across all ten cities evaluated. Furthermore, the HI for the adult demographic exceeded 1.0 (specifically 1.23) exclusively in Qorwe city. The study also identified a high carcinogenic risk associated with lead across the province, which has a carcinogenic risk of 7.3 × 10-03 in 10 studied cities, which is more than the guideline value of 10-04. The findings underscore the urgent need for continuous monitoring and the implementation of preventive measures to safeguard public health. The results provide crucial insights for policymakers and health authorities, facilitating informed decisions to mitigate the health risks posed by HM contamination in the region's groundwater.

Performance of public drinking water purifiers in control of trihalomethanes, antibiotics and antibiotic resistance genes

Point-of-use water purifiers are widely applied as a terminal treatment device to produce drinking water with high quality. However, concerns are raised regarding low efficiency in eliminating emerging organic pollutants. To enhance our understanding of the reliability and potential risks of water purifiers, the removal of trihalomethanes, antibiotics, and antibiotic resistance genes (ARGs) in four public water purifiers was investigated. In the four public water purifiers in October and November, the removal efficiencies of trichloromethane (TCM) and bromodichloromethane (BDCM) were 15%-69% (averagely 37%) and 6%-44% (averagely 23%). The levels of TCM and BDCM were lowered by all water purifiers in October and November, but accelerated in effluent compared to the influent in one public water purifier in December. The removal efficiencies of twelve antibiotics greatly varied with species and time. Out of twelve sampling cases, the removal efficiencies of total antibiotics were 25%-75% in ten cases. In the other two cases, very low removal efficiency (6%) or higher levels of antibiotics present in effluent compared to the influent were observed. Two public water purifiers effectively remove ARGs from water, with log removal rates of 0.45 log-3.89 log. However, in the other two public water purifiers, the ARG abundance accidently increased in the effluents. Overall, public water purifiers were more effective in removing antibiotics and ARGs compared to household water purifiers, but less or equally effective in removing trihalomethanes. Both public and household water purifiers could be contaminated and release the accumulated micro-pollutants or biofilm-related pollutants into effluent. The production frequency and standing time of water within water purifiers can impact the internal contamination and purification efficacy.