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We conducted a pilot study to examine pesticides in dust of homes in a rural county of Taiwan. A total of 56 homes of pregnant women were included in the study. Indoor and outdoor dust was collected by a vacuum sampler and a dustpan/brush set, respectively. Nine pesticides were selected for analysis on gas chromatography-mass spectrometry with the detection limits being 0.088 ng/g or lower. The most detected pesticides were cypermethrin and chlorpyrifos, which appeared in 82.7 and 78.8% of indoor samples and 48.2 and 39.3% of outdoor samples, respectively. The detection of pesticides from indoor and outdoor dust, however, was not consistent, indicating different sources of pesticides. In addition to those two most detected, permethrin, prallethrin, and tetramethrin, which were common ingredients of insecticide products for indoor use, were also frequently found in indoor dust, suggesting that indoor use of such pesticide products may have been a major source. Fewer pesticides were found in outdoor dust, but the outdoor detection of chlorpyrifos was significantly associated with farms present inside the circles with radii of 50 and 100 m surrounding the homes (P = 0.021, 0.016). It is suggested that pesticide drift from agricultural areas to residential environments may have occurred. No seasonal effect on distribution of pesticides in dust was found, indicating that pesticides could be routinely used in Taiwan regardless of season. Compared with other international studies, this study shows relatively high levels of chlorpyrifos but low levels of pyrethroids (i.e., cypermethrin), reflecting a different pattern of pesticide use in Taiwan. Further studies need to be warranted for a better understanding of exposure to pesticides and the associated health effects.

We estimated the daily intakes of chlorpyrifos and cypermethrin via ingestion of indoor dust and outdoor soils using the Stochastic Human Exposure and Dose Simulation Model on a probabilistic approach for Taiwanese young children. Variables for the estimation, such as concentration, ingestion rate, and body weight, were adopted from previous studies. Monte Carlo simulation was performed with 1,000,000 iterations to simulate a single daily intake, which was shown in terms of percentage of the Acceptable Daily Intake (ADI) of either insecticide. The daily intakes are minimal with a 99% probability, but go up steeply at the 99.9th percentile (13.1% and 20.0% of the ADIs of chlorpyrifos and cypermethrin, respectively). The sensitivity analysis indicates that concentration is the most determinant variable for daily intake estimation, suggesting that high intakes may occur when insecticide concentrations are elevated. Compared to the data of daily intakes via dietary ingestion of vegetables derived from a previous study, the estimated non-dietary intakes are negligible until reaching the highest percentile. Consequently, the non-dietary ingestion exposure to either insecticide is commonly low for young children in Taiwan’s homes, unless high contamination (e.g., indoor insecticide application) occurs in the environment. Care has to be taken to avoid high contamination indoors.