Chloroform exposure in air and water in Swedish indoor swimming pools—urine as a biomarker of occupational exposure

INTRODUCTION: Disinfection by-products are produced in water disinfected with chlorine-based products. One such group is trihalomethanes, and chloroform is the most abundant trihalomethane in swimming pool areas. Chloroform can be absorbed by inhalation, ingestion, and dermal absorption, and is classified as possibly carcinogenic. AIM: To investigate if chloroform concentrations in air and water affect the chloroform concentration in urine samples of exposed swimming pool workers. METHODS: Workers from 5 adventure indoor swimming pools carried personal chloroform air samplers and provided up to 4 urine samples during one workday. Chloroform concentrations were analyzed with a linear mixed model analysis to investigate a possible correlation between air and urine concentrations. RESULTS: The geometric mean chloroform concentration was 11 μg/m(3) in air and 0.009 µg/g creatinine in urine among individuals with ≤2 h at work, 0.023 µg/g creatinine among those with >2–5 working hours, and 0.026 µg/g creatinine in the group with >5–10 working hours. A risk of higher levels of chloroform in urine was associated with longer hours at work (≤2 h versus >5–10 h, odds ratio [OR] 2.04, 95% confidence interval [CI] 1.25–3.34), personal chloroform concentrations in air (≤17.00 µg/m(3) versus >28.00 µg/m(3), OR 9.23, 95% CI 3.68–23.13) and working at least half the working day near the swimming pools (OR 3.16, 95% CI 1.33–7.55). Executing work tasks in the swimming pool water was not associated with higher chloroform concentrations in urine compared to only working on land (OR 0.82, 95% CI 0.27–2.45). CONCLUSION: There is an accumulation of chloroform concentrations in urine during a workday and a correlation between personal air and urine concentrations of chloroform among workers in Swedish indoor swimming pools.