Actual priority of DEET and triclosan: Letter to the editor on “Emerging Organic Contaminants in Chinese Surface Water: Identification of Priority Pollutants”

We have read an article by (Zhong et al. 2021) published in Engineering , and critical errors were observed in the calculation of human health risk quotient (RQ hum ) and the prioritization scheme. Zhong and co-authors adopted acceptable daily intake (ADI) values of 0.082 μg/kg/day for DEET and 0.19 μg/kg/day for triclosan, as shown in Table S4 of the original article.These values were cited from a review by Murray et al. (2010). However, as we have addressed previously (Yoshida et al. 2021; Fujitani et al. 2022), the ADIs of DEET and triclosan were not correct. Original study byBlanset et al. (2007) derived the correct values, 100 μg/kg/day and 50 μg/kg/day for DEET and triclosan, respectively. Zhong et al. calculated predicted no effect concentrations (PNECs) and RQ values from the incorrect ADIs. Therefore, an overestimation of more than 200- to 1000-fold for RQ hum values occurred as shown in Table 1. As a result, DEET and triclosan would be no longer priotized in this assessment.