p-Phenylenediamine Derivatives in Tap Water: Implications for Human Exposure

Human exposure to p-phenylenediamine derivatives (PPDs) may induce hepatotoxicity and altered glycolipid metabolism. Recent studies have demonstrated the wide presence of PPDs in environmental matrixes. However, until now, the occurrence of PPDs in tap water has not been well known. This study analyzed nine PPDs in tap water collected from Hangzhou and Taizhou, China. The results showed that seven PPDs were detected in tap water samples from Hangzhou (n = 131), with the concentration of total detected PPDs ranging from 0.29 to 7.9 ng/L (mean: 1.6 ng/L). N-(1, 3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD; mean: 0.79 ng/L, <LOD−5.7 ng/L) was the predominant PPD in tap water from Hangzhou, followed by N, N′-di-2-butyl-p-phenylenediamine (44PD; 0.39 ng/L, <LOD−2.2 ng/L) and N-isopropyl-N′-phenyl-1, 4-phenylenediamine (IPPD; 0.31 ng/L, <LOD−1.4 ng/L). Five PPDs were detected in tap water collected from Taizhou (n = 30). N-phenyl-N′-cyclohexyl-p-phenylenediamine (CPPD; mean: 1.0 ng/L, <LOD−4.2 ng/L) was the predominant PPD in tap water from Taizhou, followed by 6PPD (0.93 ng/L, <LOD−2.6 ng/L) and 44PD (0.78 ng/L, <LOD−1.8 ng/L). The mean daily intake (DI) of PPDs for adults and children in Hangzhou was estimated to be 4.9–24 and 6.4–32 pg/kg bw/day, respectively. Meanwhile, the mean DI of PPDs for adults and children living in Taizhou was 11–31 and 14–40 pg/kg bw/day, respectively. To our knowledge, this study provides the first data on the occurrence of PPDs in tap water, which is vital for human exposure risk assessment.