Complementary roles of drinking water and rice in mineral intake and metal exposure: Insights from a longevity region in Southern Hainan, China

• Rice is main source of both nutrients and health risks in Hainan longevity area. • Children face significant health risks from rice arsenic and chromium exposure. • Hainan water is mineral-poor but clean with negligible health risks. • Arsenic and chromium co-transport with nutrients in rice physiology. • Complementary water-rice exposure suggests balanced dietary profile. Growing concerns over aging and food safety highlight the need to evaluate both nutritional benefits and toxic risks in daily diets. This study assessed exposure to 27 elements in drinking water and rice from southern Hainan, China—a recognized longevity region. Of the samples analyzed, 10.4% of water and 18.8% of rice were non-compliant with national safety standards. Using Monte Carlo simulation, we estimated the probabilistic intake of essential minerals and assessed non-carcinogenic risks from heavy meta(loid)s. Drinking water contributed little to mineral intake, covering at most 10.9% of Mn needs for children and 21.6% for adults. In contrast, rice was identified as a major dietary source of Fe, Zn, Mg, Cu, and P, with Cr intake reaching 639.8% and 853.1% of the recommended daily levels for children and adults, respectively. Health risk assessments showed negligible risks from water but higher risks from rice, especially for children. Arsenic in rice was the dominant risk driver, followed by Cr. Multivariate statistics confirmed these elements are co-transported with essential nutrients during plant uptake, suggesting that simply cleaning soils may be insufficient for reducing their presence in grains. This calls for an integrated approach that combines source control with targeted farming practices to reduce co-uptake of contaminants and nutrients. Cross-regional comparisons with 21 global regions revealed a complementary exposure profile in southern Hainan: while the drinking water is mineral-poor but safe, locally produced rice is nutrient-rich and poses manageable health risks.