ABSTRACT
Background Neonicotinoid insecticides (NEOs) are emerging synthetic insecticides that have been used in various pest management regimens worldwide as alternatives to conventional insecticides. Recently, several studies have indicated that humans are widely exposed to NEOs, but limited is known about the levels and associated health risks of NEOs exposure among children. Objective To estimate exposure levels of four kinds of NEOs in urine samples among 5-year-old children from Laizhou Wan, Shandong Province, and to evaluate health risks of single and cumulative exposure to NEOs among children in this area. Methods A total of 205 children who participated in the 5-year-old follow-up in Laizhou Wan Birth Cohort (LWBC) were included. Urinary concentrations of four NEOs [imidacloprid (IMI), acetamiprid (ACE), clothianidin (CLO), and thiamethoxam (THM)] were measured by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry. Based on the detected NEOs concentrations, estimated daily intake (EDI) was calculated, and the health risk of exposure to single NEO was assessed using hazard quotient (HQ, risk threshold=1). A relative potency factor (RPF) approach was used to standardize the concentrations of the four NEOs by IMI to calculate their cumulative concentrations. Then, the health risk of cumulative exposure to the four NEOs was further evaluated based on the HQ method. Results The detection rates of the four NEOs in the 5-year-old children were all above 90%, and their median creatinine-adjusted urinary concentrations were in the order from high to low as follows: CLO (1.373 μg·g−1) > THM (0.628 μg·g−1) > IMI (0.310 μg·g−1) > ACE (0.073 μg·g−1). Of the four NEOs, the median EDI of IMI was 0.035 µg·kg−1·d−1, higher than those of CLO (0.032 µg·kg−1·d−1), THM (0.012 µg·kg−1·d−1), and ACE (0.002 µg·kg−1·d−1). The maximum HQ values of IMI, CLO, THM, and ACE were 0.168, 0.152, 0.055, and 0.022, respectively, which were all far lower than the risk threshold of 1. The median concentration of cumulative exposure to the four NEOs standardized by IMI was 21.241 μg·g−1, and its median EDI was 2.370 µg·kg−1·d−1. The maximum HQ of cumulative exposure to the four NEOs was only 0.694, which also did not exceed the risk threshold of 1. Conclusion NEOs exposure is common among the 5-year-old children in Laizhou Wan, Shandong. Although there is no obvious health risk associated with single and cumulative exposure to NEOs in the children in this area, their exposure levels of NEOs are higher than those in some foreign areas. The adverse health effects of long-term exposure to low dose of NEOs deserve our extensive attention.