Evaluating 1,4-Dioxane Exposure in Long Island, New York: Integrating Environmental, Biological, and Metabolomic Measures

1,4-Dioxane (1,4-DX), found in solvents and personal care products, is a potential carcinogen with limited exposure data. Tap water, blood samples, and interviews were collected from 92 residents of Long Island, New York, an area with historically high 1,4-DX drinking water concentrations. We assessed the relationship between water and blood 1,4-DX concentrations, evaluated exposure determinants, and compared metabolomic profiles by exposure status. 1,4-DX was detected in 32% of water and 24% of blood samples; 24% of water samples exceeded New York's Maximum Contaminant Level (MCL) of 1 μg/L. Water and blood 1,4-DX concentrations were not correlated (<i>r</i> = -0.11, <i>p</i> = 0.32). Older homes (built <1960) and those without a whole-house treatment system were more likely to have detectable 1,4-DX in tap water (<i>p</i> < 0.05). Water consumption and personal care product use were not associated with blood 1,4-DX. Metabolomic analyses revealed small but significant differences in redox and energy metabolism among those with and without detectable water 1,4-DX (fold change <20%, false-discovery-rate-corrected <i>p</i> < 0.05). The lack of correlation between 1,4-DX in paired water and blood samples suggests other exposure sources or differing time windows captured by sample types. Larger studies could clarify exposure determinants and metabolomic impacts to better assess the potential health burden of 1,4-DX.