Heavy metals in drinking water sources in northern Mexico: a review of concentrations and human health risks assessment.

Despite the high concentrations of heavy metals (HMs) in the water bodies of northern Mexico, current monitoring efforts and regulations are insufficient. This is especially troubling, given the indigenous and vulnerable communities and the overall lack of public health information. To characterize exposure, we conducted an exhaustive review of HM studies in drinking water in northern Mexico. This information was used to estimate hazard quotient (HQ) and carcinogenic risk (CR) values by age for all of northern Mexico. In total, 316 concentrations of HMs were reported in 55 studies from 1975 to 2021, with concentration ranges of 0-11,100, 0-5,250, 0-350, 0-25, and 0-9,470 μg/L for arsenic, cadmium, chromium, mercury, and lead, respectively. The probable maximum concentrations (95th percentile) of metals in drinking water were 244.55, 10, 56, 1.68, and 90.35 μg/L for arsenic, cadmium, chromium, mercury, and lead, respectively. The HQ for all HMs ranged from 0.0011 to 404.62. Children younger than 2 years had an extremely high risk (HQ > 40) of presenting adverse health effects from arsenic consumption. Children younger than 6 years had the highest risk of developing cancer, with CR values from 2.24 × 10 to 7.77 × 10, emphasizing the need for continuous HM monitoring in northern Mexico.