Levels and inhalation health risk of neonicotinoid insecticides in fine particulate matter (PM2.5) in urban and rural areas of China

Neonicotinoid insecticide (NEO) concentrations in ambient fine particulate matter (PM2.5) and daily exposure via inhalation were investigated during spring and fall in an urban area in Beijing and in urban and rural areas of Zhengzhou, Henan Province, China. Four NEOs, including imidacloprid, acetamiprid, thiamethoxam and dothianidin, were assessed using a QuEChERS (quick, easy, cheap, effective, rugged, safe) extraction procedure coupled to liquid chromatography-tandem mass spectrometry. Of 64 PM2.5 samples, 100% contained at least two NEOs (imidacloprid and acetamiprid). Imidacloprid was detected at the highest levels, ranging from 4.33 to 1.13 x 10(2) pg m(-3) . A relative potency factor method that considered different toxicities was used to integrate the four NEO concentrations. The total NEO concentrations in air in the Zhengzhou rural area (mean: 80.86 pg m(-3)) were higher than those in urban areas. Differences between seasons were not significant (p > 0.05). The highest value for the total average daily dose via inhalation of four NEO5 (ADD(inh,total)), 91.0 pg kg(-1) day(-1) , was found in rural children < 6 years old. The ADD(inh)(,total) of rural residents was significantly higher than that of urban residents when there was no intensive pesticide application. Although the ADD(inh,total) values were below the current chronic reference dose, when possible joint toxicity and the increasing use of NEO5 are considered, a potential health risk via inhalation is evident. We believe this study is the first to characterize NEO levels in fine particulate matter and to evaluate inhalation exposure in urban and rural residents under nonoccupational scenarios in China. It will enhance our understanding of exposure to NEOs and provide a basis for risk management decisions.