Urinary parabens and triclosan concentrations and associated exposure characteristics in a Korean population-A comparison between night-time and first-morning urine

Among the target compounds, EtP and MeP were most frequently detected at the highest concentrations. The median concentration of EtP in night-time urine was 32.4 μg/L (interquartile range: 8.37-82.8 μg/L), which is higher than previously reported worldwide. Unlike other test compounds, compared to those measured from first-morning urine, the EtP concentrations were significantly higher in night-time urine, suggesting the presence of different exposure sources. Among adults, the MeP and PrP concentrations in night-time urine were associated with frequent use of skin care products, colored cosmetics, bath products, toothpaste, vinyl food packaging, or consumption of canned food. The MeP and PrP concentrations were higher in females than in males, especially in night-time urine. The results of this study also show that multiple urine samples are necessary to capture the diurnal variation of non-occupational exposure to environmental chemicals, such as parabens.