Arsenic levels in the hair of people exposed to arsenic and awareness of its risk factors Original paper

What was studied?

This cross-sectional study examined arsenic hair levels and risk factors by measuring arsenic in household water, home-grown wheat, and human hair from residents of an arsenic-affected rural area and a nearby low-arsenic control. The investigators quantified arsenic with ICP-MS and paired biomarker data with questionnaires on demographics and behaviors, then used group comparisons and multivariable regression to identify exposure drivers. The central aim was to determine whether environmental media in the exposed area exceeded safety limits and whether individual factors such as age, sex, residence time, wheat intake, smoking, and bathing habits explained variation in hair arsenic, a long-term exposure marker relevant to clinical risk assessment and microbiome exposure modeling.

Who was studied?

Adults aged 18 years and older with at least three years of residence were recruited from two rural communities on the Guanzhong Plain, China. Ninety-nine participants from the arsenic-contaminated area and forty-one from the control area provided hair samples; 150 drinking-water and 87 wheat samples from the exposed area, and 15 water and 10 wheat samples from the control, characterized local media. Participants completed structured questionnaires that captured water source and intake, wheat-based food intake, bathing time, tobacco and alcohol use, disease history, and residence duration. Ethical approval and informed consent procedures were in place.

Most important findings

Drinking water in the exposed area frequently exceeded the 10 µg/L standard, with 89.33% of samples above the limit, while only 2.13% of wheat samples surpassed 0.5 mg/kg; all control-area media were within limits. Mean hair arsenic was higher in the exposed community than the control (0.967 vs 0.392 mg/kg), and 29.29% of exposed residents had hair arsenic above 1 mg/kg. Hair arsenic distributions differed significantly between areas. In univariate analyses, higher hair arsenic associated with male sex, older age, longer residence (>60 years), smoking, a history of chronic disease, and greater wheat-based food intake. Multivariable models identified age and male sex as independent predictors, and wheat intake as a behavioral contributor. These results position hair arsenic as a stable exposure proxy that captures both environmental load (water) and dietary pathways (wheat and preparation water).

For microbiome signature efforts, the study provides exposure strata and covariates that can reduce confounding: sex and age modify internal dose; diet links arsenic exposure to luminal chemistry; smoking may alter exposure and host processing. Together, these elements enable cleaner mapping between arsenic dose and gut community shifts when integrating biomarker-defined exposure into microbiome analyses.

Key implications

For clinicians, hair arsenic offers an accessible, long-term marker to screen patients from endemic regions, triage water testing, and contextualize dermatologic findings. For microbiome researchers, using hair arsenic to stratify cohorts can sharpen exposure–microbiome associations and improve the fidelity of signatures by accounting for sex, age, residence time, and wheat-based diet as covariates. Public health actions should prioritize safe water substitution and cooking practices that limit arsenic transfer from water to staple foods, while counseling smokers about compounded exposure risk. Programmatically, pairing household water interventions with biomarker monitoring can verify exposure reduction and support longitudinal microbiome and clinical follow-up.