Temporal Trends in Phthalate Exposures in the U.S. Population: A Quantile Regression Approach

• Activity Number: 194
• Type: Contributed
• Date/Time: Monday, August 10, 2015 : 10:30 AM to 12:20 PM
• Sponsor: ENAR
• Author(s): Min Chen* and Jennifer Foreman
• Companies: ExxonMobil Biomedical Sciences, Inc. and ExxonMobil Biomedical Sciences, Inc.
• Keywords: Quantile Regression ; Complex Survey ; Phthalate ; Exposure ; Risk Assessment ; Temporal Trends

Abstract

This study analyzes temporal trends in the U.S. population for five phthalates (DBP, DiBP, BBP, DEHP, DINP) at various percentiles using quantile regression for NHANES 2005-2012. Upper quantiles of these five phthalate exposure levels are critical for the cumulative risk assessment of phthalates from a public health perspective (CHAP on phthalates and phthalate alternatives). The analysis shows that there were significant decreasing trends in daily intake of DBP, BBP, and DEHP both at the median and at the 95th percentile over the period 2005-2012. Daily intake of DiBP increased at the median but not at the 95th percentile. Daily intake of DINP increased both at the median and at the 95th percentile. Specifically, daily intake of DEHP has declined since the 2005/2006 survey, and, by the 2011/2012 survey were approximately 15% the levels measured in the 2005/2006 survey for the 95th percentile. Given DEHP has been identified as the major driver for risk in multiple cumulative risk assessments (CRA) conducted with phthalates, the decrease has a significant impact on the CRA of phthalates conducted by the CHAP. Trends may be reflective of an industry move towards safer phthalates.