Assessment of chlorpyrifos exposure and absorbed daily doses among infants living in an agricultural area of the Province of Jiangsu, China

Chlorpyrifos (CPF) is one of the most widely used organophosphorous pesticides in China. However, few reports on CPF pesticide exposure and body burden of infants at 2 years of age in China are available. The aim of this study was to assess the exposure level and the absorbed daily dose (ADD) of CPF among infants from an agricultural area of Jiangsu, China, and determine whether the infants' estimated dose exceeds the recommended reference dose (RfD) and the population adjusted dose (PAD) set by U.S. Environmental Protection Agency (EPA). In our study, 364 infants at 2 years of age who lived in the agricultural area of Jiangsu Province (China) were enrolled into the biomonitoring study from June 2011 to January 2012. CPF exposure was estimated based on both questionnaire survey and measured results of urinary metabolite 3,5,6-trichloro-2-pyridinol (TCPy) of CPF by high-performance liquid chromatography. Furthermore, the ADD of CPF among infants was also evaluated and compared with the RfD and the PAD values issued by EPA. Urinary TCPy was detected in more than 70 % of the urine samples among 364 infants. The unadjusted and creatinine-adjusted geometric means in these subjects for TCPy were 1.33 mu g/L and 6.73 mu g/g Cre., respectively. Infants lived nearby (100 m distance) plantations or green parks present significantly higher levels of urinary TCPy than those lived far away (p = 0.045). Urinary TCPy levels were also significantly higher in infants who had frequent hand-to-mouth activities than those with less frequency (p = 0.037). Urinary TCPy concentrations in the infants at 2 years of age in Jiangsu were lower than those in the children at 2-6 years of age in the USA. The median estimated ADD of CPF in this study (0.07 mu g/kg/day) was much lower than the acute and chronic RfDs (5 and 0.3 mu g/kg/day, respectively) announced by EPA, but higher than the chronic PAD (cPAD) (0.03 mu g/kg/day) for children. Additionally, the 75th percentile of the estimated ADD in our study was 2.5 times as much as the cPAD from EPA, even assuming only half of the TCPy amount from CPF exposure. Our findings revealed that infants at 2 years of age in Jiangsu of China were widely exposed to CPF pesticide. The estimated ADD probably suggested that about 25 % of the enrolled infants were at potential risk of pesticide exposure, which warned of urgency to eliminate the potential exposure risk to infants living in agricultural areas of China.