Potential health risk assessment of mixtures of heavy metals in drinking water

Despite the potential to cause chronic adverse effects, heavy metals screenings are not typically as frequent or exhaustive as those for bacterial contamination. Additionally, there is a pressing need for collectively assessing heavy metals as a mixture rather than individual allowed limits. We tested a hypothesis that comprehensive methodical wide screening for heavy metals can inform the magnitude of potential exposures and aid in classifying heavy metals collectively as hazardous rather than individual level comparisons. A total of 297 samples were taken by proportional cluster sampling from different households in Irbid governorate, depending on population density in each district. We analyzed the samples using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Our analysis looked at individual levels of heavy metal clustering in different water sources and regions and calculated a heavy metals pollution index (HPI) in five different types of drinking water: harvested rainwater, bottled water, spring water, water shop, and tap water. Pb and Fe were the main contaminants in drinking water, especially tap and harvested rainwater. High amounts of essential metals were found in tap, harvested rain, and spring waters compared to water shop and bottled water. HPI was above critical value in 29 samples, all of which were harvested rainwater samples, and most of which came from Wasateya and Taiba regions. Spring and tap water had similar heavy metal patterns. This experimental approach provides a guide for clustering water sources in their heavy metal patterns and for classification of heavy metals as mixtures rather than individual limits; it also fills crucial gaps in prioritization of heavy metal testing according to water type and metal correlations. Furthermore, this study presents the first data on drinking water quality in Jordan to be published in over a decade.