Comparison of urinary concentrations of 3-phenoxybenzoic acid among general residents in rural and suburban areas and employees of pest control firms

Objectives: The purpose of this study is to determine the levels of urinary 3-phenoxybenzoic acid (3-PBA) among general populations in rural and suburban areas and employees of pest control firms to evaluate the differences in the level of environmental or occupational pyrethroid (PYR) pesticides to which those populations are exposed. Methods: Spot urine specimens were collected from male residents in a rural area (n = 143) and male residents in a suburban area (n = 66) in August of 2005 and 2007, respectively. Male employees of pest control firms, who also provided their urine specimens at the time of a health-checkup in August 2007, were classified either as sprayers (n = 14) or as non-sprayers (n = 16) according to the presence of spraying during the pre-checkup week. Urinary concentrations of 3-PBA were determined using gas chromatography - mass spectrometry and corrected for the urinary creatinine concentrations. An analysis of covariance was used to examine the statistical difference in 3-PBA concentrations between these four groups after adjustment for age, body mass index, and current smoking/drinking habits. Results: Multiple comparisons indicated no differences in adjusted 3-PBA concentrations between the groups of general residents from the rural areas (0.33 μg/g cre in geometric mean) and suburban area (0.51 μg/g cre). The group of sprayers showed a much higher level of 3-PBA concentrations (25.0 μg/g cre) than the other three groups. A statistically significant difference, though to a lesser extent, was also exhibited in 3-PBA concentrations between the group of non-sprayers (5.6 μg/g cre) and that of general residents. Conclusions: The results indicated that the levels of background low-dose exposure to PYRs are not likely to differ evidently among general populations according to the area of residence. Moreover, employees of pest control firms, who have been away from PYR spraying operations for a week or more, still retain much higher urinary 3-PBA concentrations than general populations.