Biomarker-Determined Nonylphenol Exposure and Associated Risks in Children of Thailand, Indonesia, and Saudi Arabia

Nonylphenol (NP) is an endocrine disruptor and environmental contaminant. Yet, data on individual body burdens and potential health risks in humans, especially among children, are scarce. We analyzed two specific urinary NP metabolites, hydroxy-NP (OH-NP) and oxo-NP. In contrast to parent NP, OH-NP has a much higher urinary excretion fraction (Fue), and both are insusceptible to external contamination. We investigated spot urine samples from school children of Thailand (n = 104), Indonesia (n = 89), and Saudi Arabia (n = 108) and could quantify OH-NP in 100% of Indonesian and Saudi children (median concentrations: 8.12 and 8.57 mu g/L) and in 76% of Thai children (1.07 mu g/L). Median oxo-NP concentrations were 0.95, 1.10, and < 0.25 mu g/L, respectively, in line with its lower Fue. Median daily NP intakes (DIs), back-calculated from urinary OH-NP concentrations, were significantly higher in Indonesia and Saudi Arabia [0.47 and 0.36 mu g/(kg bw & BULL;d), respectively] than in Thailand [0.06 mu g/(kg bw & BULL;d)]. Maximum DIs were close to the preliminary tolerable DI of 5 mu g/(kg bw & BULL;d) from the Danish Environmental Protection Agency. Dominant sources of exposure or relevant exposure pathways could not be readily identified by questionnaire analyses and also potentially varied by region. The novel biomarkers provide long-needed support to the quantitative exposure and risk assessment of NP.

Automated summary

Nonylphenol (NP), an endocrine disruptor and environmental contaminant, has limited data on individual body burdens and potential health risks in humans, especially children. This study analyzed urine samples from school children in Thailand, Indonesia, and Saudi Arabia, and found that Indonesian and Saudi children had significantly higher NP intakes compared to Thai children. The findings provide support for quantitative exposure and risk assessment of NP using novel biomarkers.