Urinary Phthalate Metabolites and Slow Walking Speed in the Korean Elderly Environmental Panel II Study

Abstract

BACKGROUND: Previous epidemiological studies have suggested that phthalate exposure may contribute to neurocognitive and neurobehavioral disor-ders and decreased muscle strength and bone mass, all of which may be associated with reduced physical performance. Walking speed is a reliable assessment tool for measuring physical performance in adults age 60 y and older. OBJECTIVE: We investigated associations between urinary phthalate metabolites and slowness of walking speed in community-dwelling adults ages 60-98 y.METHODS: We analyzed 1,190 older adults [range, 60-98 y of age; mean +/- standard deviation oSD thorn , 74.81 +/- 5.99] from the Korean Elderly Environmental Panel II study and measured repeatedly up to three times between 2012 and 2014. Phthalate exposure was estimated using the follow-ing phthalate metabolites in urine samples: mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono -n-butyl phthalate (MnBP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono-benzyl phthalate (MBzP). Slowness was defined as a walking speed of <1.0 meter/second. We used logistic and linear regression models to evaluate the association between each urinary phthalate metabolite and slowness or walking-speed change. We also used Bayesian kernel machine regression (BKMR) to examine overall mixture effects on walking speed.RESULTS: At enrollment, MBzP levels were associated with an increased odds of slowness [odds ratio (OR) per doubling increase: 1.15, 95% confi-dence interval (CI): 1.02, 1.30; OR for the highest vs. lowest quartile: 2.20 (95% CI: 1.12, 4.35) with p-trend across quartiles = 0.031]. In longitudinal analyses, MEHHP levels showed an increased risk of slowness [OR per doubling increase: 1.15 (95% CI: 1.02, 1.29), OR for the highest vs. lowest quartile: 1.47 (95% CI: 1.04, 2.06), p-trend = 0.035]; whereas those with higher MnBP showed a reduced risk of slowness [OR per doubling increase: 0.84 (95% CI: 0.74, 0.96), OR in the highest (vs. lowest) quartile: 0.64 (95% CI: 0.47, 0.87), p-trend = 0.006]. For linear regression models, MBzP quartiles were associated with slower walking speed (p-trend = 0.048) at enrollment, whereas MEHHP quartiles were associated with slower walking speed, and MnBP quartiles were associated with faster walking speed in longitudinal analysis (p-trend = 0.026 and <0.001, respectively). Further, the BKMR analysis revealed negative overall trends between the phthalate metabolite mixtures and walking speed and DEHP group (MEHHP, MEOHP, and MECPP) had the main effect of the overall mixture.DISCUSSION: Urinary concentrations of prevalent phthalates exhibited significant associations with slow walking speed in adults ages 60-98 y. https:// doi.org/10.1289/EHP10549