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An Analysis of Cumulative Risks Indicated by Biomonitoring Data of Six Phthalates Using the Maximum Cumulative Ratio
Citation:
Reyes, J. AND P. Price. An Analysis of Cumulative Risks Indicated by Biomonitoring Data of Six Phthalates Using the Maximum Cumulative Ratio. 2017 Society of Toxicology Annual Meeting, Baltimore, MD, March 12 - 16, 2017.
Impact/Purpose:
This abstract presents the results of a new and novel analysis of phthalate biomonitoring data for phthalates that is based on the patterns of co-exposure for six phthalates. Phthalates are a group of chemicals that have been identified by the NAS as having a significant potential for causing combined effects when individuals are exposed to more then one of the compounds. The analysis suggests a modest impact of combined exposures for six phthalates in individuals ages six years and above.
Description:
The Maximum Cumulative Ratio (MCR) quantifies the degree to which a single component of a chemical mixture drives the cumulative risk of a receptor.1 This study used the MCR, the Hazard Index (HI) and Hazard Quotient (HQ) to evaluate co-exposures to six phthalates using biomonitoring data in 2454 individuals aged 6 years and older from the 2011-12 cycle of the National Health and Nutrition Examination Survey. The values of MCR, HI and phthalate-specific HQs were determined by calculating steady-state doses consistent with the concentrations of phthalate metabolites in urine and using Tolerable Daily Intake values.2 There were 22 individuals (0.9%) predicted to have at least one HQ value > 1 and an additional 17 (0.7%) with no HQ value > 1 but with an HI value > 1. The percent of individuals with HI values > 1 differed by age (0.9% for individuals between 6 – 17 y and 1.9% for individuals > 17 y). There is a statistically significant negative relationship between HI and MCR values in both age groups (p-values 1 and all HQs 1 were 1.1 (1.0-1.3) and 2.8 (1.1-13.7), respectively. The combined assessment found that 17/39 (43%) of the individuals with HI values > 1 are missed by chemical-by-chemical assessments of the phthalates. These findings suggest that determining combined exposures for the six phthalates has a modest impact on the predictions of the chemicals’ risks. Additional individuals with HI values >1 are identified, but HI values in these individuals are close to 1 (<1.3). Individuals with the largest HI values are identified by chemical-by-chemical assessments. The views expressed in this abstract are those of the authors and do not necessarily reflect the views or policies of the U.S. EPA.
