Occurrence of perchlorate, chlorate and bromate in drinking water in Shenzhen and related human exposure risks

Perchlorate, chlorate and bromate are ubiquitously present in the environment. Perchlorate and chlorate could affect thyroid functions, while bromate is carcinogenic and has been listed as a possible human carcinogen in group 2B by the International Agency for Research on Cancer (IARC). This study aimed to determine the occurrence of perchlorate, chlorate and bromate in three types of drinking water (n=226) in Shenzhen, and assess potential human exposure risks. The detection rates of chlorate and perchlorate were both greater than 60%, and they were positively correlated in both bottled water and tap water, indicating similar sources. Bromate and chlorate were negatively correlated in tap water, indicating that the production of them in tap water disinfection might restrict each other. The hazard quotient (HQ) and hazard index (HI) values of perchlorate, chlorate and bromate in drinking water were less than 1 regardless of age groups. However, for bromate some individual excess cancer risk (ICER) values in drinking water exceeded the maximum acceptable level, indicating potential cancer risk to Shenzhen residents.