Organophosphate ester exposure among Chinese waste incinerator workers: Urinary levels, risk assessment and associations with oxidative stress

Organophosphate esters (OPEs), which are frequently used as flame retardants and plasticizers in versatile products, are readily released to the external environment. Although workers at municipal waste incineration plants may be extensively exposed to OPEs, only scarce health monitoring and risk assessments have been conducted in this population. In this study, we investigated the levels of eight metabolites of organophosphate esters (mOPEs) and the oxidative stress marker 8-hydroxy-2-deoxyguanosine (8-OHdG) in urine samples from 73 waste incinerator workers and 97 general residents from Shenzhen, China between September 2016 and June 2017. The overall detection rate of mOPEs was 82.2 %–100 %, and higher concentrations of di-p-cresyl phosphate and chlorinated mOPEs [bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2propyl) phosphate (BCIPP), bis(1,3-dichloro-2-propyl) phosphate) (BDCIPP)] were found among incinerator workers than among general residents. The incinerator workers also showed significantly higher levels of 8-OHdG than general residents, but the measured levels of most mOPEs were not significantly correlated with the level of 8-OHdG; this may be because co-exposure to multiple toxic compounds can lead to oxidative stress. Risk assessment using Monte Carlo simulations revealed that 95 % of the incinerator workers were free from non-carcinogenic effects due to OPEs exposure (hazard index = 0.27, 95 % CI: 0.09, 0.77). However, the carcinogenic risk of tris(2-chloroethyl) phosphate (TCEP) for incinerator workers was between 10−6 and 10−4. These results indicate that incinerator workers are extensively exposed to OPEs, and better protective measures need to be implemented.