Provenance of drinking water revealed through compliance sampling

Assessment of the groundwater quality, physicochemical composition, and human and ecological health risks in a coastal metropolitan: A case study of a residential estate in Lagos, Nigeria

Water is essential for humankind's existence, providing food security, amongst others, as well as promoting industrial and economic development. The physicochemical composition, potentially toxic metals, water quality index, human health, and ecological risks of groundwater in a residential estate in Lagos, Nigeria, were studied to assess their possibility for drinking and domestic purposes. Groundwater samples were collected from twelve designated sites and analysed using standard methods. TDS and pH values of 5.4 ± 1.7-20.8 ± 0.84 and 5.08 ± 0.26-5.56 ± 0.57, respectively, were recorded for the groundwater samples whereas DO and BOD were detected at 4.2 ± 1.2-5.45 ± 0.52 mg O₂/L and 2.6 ± 1.2-24.6 ± 5.7 mg/L, respectively. Additionally, water conductivity ranged from zero to 0.60 ± 0.89 µS/cm. Of the seven PTMs (Pb, Cd, Zn, Cu, Cr, Ni, & Fe) analysed, Pb was present, over the standard limit, in all the samples whereas Fe was detected below the limit in over 83.3% of the groundwater sampled. The hazard index (HI) indicated that 83.3% and 100% of the samples were within the acceptable limits, with no health risks, for the children and adult groups, respectively. WQI showed that 75.0% of the samples was of good quality and suitable for domestic purposes, with low ecological and carcinogenic health risks. The results show that the groundwater samples are good for domestic purposes but require pre-treatment to make them safe for drinking.

Associations between UK tap water and gut microbiota composition suggest the gut microbiome as a potential mediator of health differences linked to water quality

Tap water composition has been widely linked to differences in human health, however the biological pathways underlying this association are less clearly defined. We provide the first investigation of the potential for the gut microbiota to mediate this association. Tap water samples and drinking habits from 85 Mono-zygotic twins with existing faecal microbiota profiles from around the UK were used to assess associations of water composition with the gut microbiome. Water composition was captured using the first 3 principle components (PCs) from multiple factor analysis of ion concentrations, additionally estimating average daily dose (ADD) of the primary three solutes contributing to its variance: chloride, sulphate and sodium. Geographic differences in water composition were assessed. We used measures of faecal microbial diversity, between-individual differences in composition and differences in taxa abundance estimated from 16S rRNA sequencing data. Differences between twin pairs were also considered. We observed significant associations of sodium ADD with microbiota diversity (Chao1), chloride, sodium and sulphate ADD with dissimilarity between samples, and significant associations for all PCs and ADD-adjusted solutes with abundances of individual microbial taxa. These results support the hypothesis that the gut microbiota could mediate the effects of tap water composition on host health, warranting further investigation into tap-water as an influencer of microbiota composition.

Cumulative risk analysis of carcinogenic contaminants in United States drinking water

Cumulative risk analysis of contaminant occurrence in United States drinking water for the period of 2010-2017 indicates that over 100,000 lifetime cancer cases could be due to carcinogenic chemicals in tap water. The majority of this risk is due to the presence of arsenic, disinfection byproducts and radioactive contaminants. For different states within the U.S., cumulative cancer risk for drinking water contaminants ranges between 1 × 10^-4 and 1 × 10^-3, similar to the range of cumulative cancer risks reported for air pollutants. Overall, national attributable risk due to tap water contaminants is approximately 4 × 10^-4, which is two orders of magnitude higher than the de minimus cancer risk of one-in-a-million. Thus, decreasing the levels of chemical contaminants in drinking water represents an important opportunity for protecting public health.