Socio-Demographic Patterning of Urinary Mono-ethyl Phthalate Levels among Children and Adults in the U.S. (1999-2018)

Background: Phthalates are chemicals used to make plastics flexible and durable. They are found in clothes, varnishes, toys, pharmaceuticals, containers, and personal care products. Phthalates make their way into human bodies through ingestion, inhalation, and dermal absorption, and the breakdown of them within bodies can be measured as phthalate metabolites in urine. They pervade all aspects of the environment and our bodies, contributing to negative health outcomes. Education, SES, and gender influence where people live (their built environment), time-use patterns, occupation, treatment at healthcare facilities, and purchasing patterns; all affect phthalate exposures, and therefore phthalate metabolites in urine are also likely to vary by socio-demographic characteristics. Objectives: To study how levels of mono-ethyl phthalate (MEP) in urine samples of children and adults in the U.S. vary among key socio-demographic groups. We expect that disadvantaged groups will have the highest levels of phthalates. Methods: Using quantitative methods, we analyze levels of urinary MEP as a biomarker indicating exposure to phthalates. Within the National Health and Nutrition Examination Survey (NHANES) (1999-2018) participants, we compare MEP levels across the following socio-demographic groups: age, gender, education, race/ethnicity, family income to poverty level, citizenship status. We use multivariate regression models to adjust results for differences in other factors that potentially influence MEP levels. Results: Historically disadvantaged groups – women, Non-Hispanic Blacks, Mexican Americans, Other Hispanics, and those with lower educational attainment – have higher predicted phthalate levels, even when holding all covariates that could be related to differences in phthalate levels by socio-demographic factors constant. Discussion: Our results suggest differences in socio-demographic factors could be leading to unequal exposures to phthalates and MEP excretions in their urine. This research contributes to understanding health experiences outside of clinical definitions, drawing attention to structural vulnerabilities and the way that environmental toxicants are embodied in individuals and populations.