U.S. Geological Survey, Columbia, SC, USA.
U.S. Geological Survey, Marlborough, MA, USA.
Environ Int. 2021 Jul;152:106487. doi: 10.1016/j.envint.2021.106487. Epub 2021 Mar 19.
Humans are primary drivers of environmental contamination worldwide, including in drinking-water resources. In the United States (US), federal and state agencies regulate and monitor public-supply drinking water while private-supply monitoring is rare; the current lack of directly comparable information on contaminant-mixture exposures and risks between private- and public-supplies undermines tapwater (TW) consumer decision-making.
We compared private- and public-supply residential point-of-use TW at Cape Cod, Massachusetts, where both supplies share the same groundwater source. TW from 10 private- and 10 public-supply homes was analyzed for 487 organic, 38 inorganic, 8 microbial indicators, and 3 in vitro bioactivities. Concentrations were compared to existing protective health-based benchmarks, and aggregated Hazard Indices (HI) of regulated and unregulated TW contaminants were calculated along with ratios of in vitro exposure-activity cutoffs.
Seventy organic and 28 inorganic constituents were detected in TW. Median detections were comparable, but median cumulative concentrations were substantially higher in public supply due to 6 chlorine-disinfected samples characterized by disinfection byproducts and corresponding lower heterotrophic plate counts. Public-supply applicable maximum contaminant (nitrate) and treatment action (lead and copper) levels were exceeded in private-supply TW samples only. Exceedances of health-based HI screening levels of concern were common to both TW supplies.
These Cape Cod results indicate comparable cumulative human-health concerns from contaminant exposures in private- and public-supply TW in a shared source-water setting. Importantly, although this study's analytical coverage exceeds that currently feasible for water purveyors or homeowners, it nevertheless is a substantial underestimation of the full breadth of contaminant mixtures documented in the environment and potentially present in drinking water.
Regardless of the supply, increased public engagement in source-water protection and drinking-water treatment, including consumer point-of-use treatment, is warranted to reduce risks associated with long-term TW contaminant exposures, especially in vulnerable populations.
人类是全球环境污染的主要驱动因素，包括饮用水资源。在美国，联邦和州机构监管和监测公共供水，而私人供水监测则很少；目前，私人和公共供水之间关于污染物混合物暴露和风险的直接可比信息缺乏，这影响了自来水（TW）消费者的决策。
我们比较了马萨诸塞州鳕鱼角的私人和公共供应住宅点源 TW，这两个供水都来自同一个地下水水源。对来自 10 个私人和 10 个公共供水家庭的 TW 进行了 487 种有机、38 种无机、8 种微生物指标和 3 种体外生物活性分析。将浓度与现有的基于保护健康的基准进行比较，并计算了受监管和不受监管的 TW 污染物的综合危害指数（HI），以及体外暴露-活性截止值的比值。
TW 中检测到 70 种有机和 28 种无机成分。中位数检测结果相当，但由于 6 个氯消毒样本中含有消毒副产物，且相应的异养平板计数较低，公共供水的中位数累积浓度要高得多。仅在私人供应的 TW 样本中超过了公共供应的适用最大污染物（硝酸盐）和处理行动（铅和铜）水平。两种 TW 供应都普遍存在超过基于健康的 HI 筛选关注水平的情况。
这些鳕鱼角的结果表明，在共享水源的情况下，来自私人和公共 TW 污染物暴露的累积人类健康问题相当。重要的是，尽管本研究的分析范围超过了目前供水商或房主可行的范围，但它仍然大大低估了环境中记录的和潜在存在于饮用水中的污染物混合物的全部范围。
无论供应情况如何，都需要增加公众对水源保护和饮用水处理的参与，包括消费者的现场处理，以降低与长期 TW 污染物暴露相关的风险，尤其是在弱势群体中。
