Association of urinary 3-phenoxybenzoic acid level with pulmonary function reduction in an urban elderly population with repeated measures data

Pyrethroids are a class of man-made insecticides associated with various adverse health outcomes including respiratory problems. However, there were limited evidences on the relation between 3-phenoxybenzoic acid (3-PBA) as a metabolite of pyrethroids and pulmonary function, particularly among elderly population who have declining pulmonary function. Therefore, we collected urine samples and performed pulmonary function test (PFT) repeatedly in a total of 559 Korean elderly living in Seoul as an urban area. After measurement of urinary 3-PBA levels, cross-sectional relations of visit-to-visit variation in 3-PBA level on visit-to-visit variation in PFT parameters were evaluated using linear mixed effect models and generalized additive mixed models after adjustment for age, sex, body mass index, smoking status, education, visit episode, and phthalate metabolite levels. The Korean elderly were highly exposed to pyrethroids with 30.2% of elderly people with 3-PBA level over reference value derived on the 95th percentile of representative samples (2 ng/mL). Forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and forced expiratory flow between 25% and 75% of FVC (FEF₂₅–₇₅) as PFT parameters showed significant reductions by an increase of 3-PBA level (FEV₁, β = −1.48, p-value < 0.01; FVC, β = −1.14, p-value < 0.01; and FEF₂₅₋₇₅, β = −1.11, p-value = 0.03). The negative associations of 3-PBA level with FEV₁, FVC, and FEF₂₅₋₇₅ were found only for females (FEV₁, β = −1.64, p-value < 0.01; FVC, β = −1.47, p-value < 0.01; and FEF₂₅₋₇₅, β = −1.06, p-value = 0.07), but not for males. However, the longitudinal effect of 3-PBA level on the trajectory of FEV₁, FVC, and FEF₂₅₋₇₅ declines in females was not found. Community-level exposure to pyrethroids was associated with pulmonary function reduction in elderly population, indicating that more stringent control of pyrethroids is necessary to protect the elderly who have declining pulmonary function.