Association Between Levels of Urine Di-(2-ethylhexyl)phthalate Exposure, a Potentially Harmful and Invisible Chemical, and Heart Rate Variability in Young Adults

BackgroundPhthalate exposure is associated with cardiovascular risk. Among the various phthalates, di-(2-ethylhexyl) phthalate (DEHP) is the most important plasticizer in our daily lives. This study investigated the association between DEHP exposure and the alteration of heart rate variability (HRV).MethodsDuring 2017-2019, we recruited 974 young adults to investigate the effects of living environments and dietary habits on cardiometabolic disorders in Taiwan. We quantitatively analyzed urinary metabolites of phthalates, including mono-(2-ethylhexyl) phthalate (MEHP), mono-(ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP). A continuous electrocardiogram was recorded to obtain a 5-minute ECG. Time-domain and frequency-domain HRV analyses were performed.ResultsMultiple linear regression showed that urinary oxidized DEHP metabolites MEHHP and MEOHP were associated with decreased HRV after controlling for associated cardiovascular risk factors. A higher MEHHP level was associated with a lower TINN (triangular interpolation of NN interval histogram), very-low-frequency (VLF), and low frequency/high frequency (LF/HF) ratio. A higher MEOHP level was associated with a decreased LF/HF ratio. In addition, trend analysis showed that higher MEHHP and MEOHP quantiles were significantly associated with a decreased LF/HF ratio.ConclusionsDEHP is a potentially harmful and invisible chemicals. The urinary DEHP metabolites MEHHP and MEOHP are associated with decreased HRV, indicating an unfavorable autonomic balance in young adults in Taiwan.