Associations between school lunch consumption and urinary phthalate metabolite concentrations in US children and adolescents: Results from NHANES 2003-2014

Abstract

Diet is a major route of phthalate exposure in humans due to use in food packaging materials. School lunches may be an important contributor to phthalate exposure in children and adolescents in the US because of the large amount of packaging necessary for mass-produced foods. We used 2003-2014 National Health and Nutrition Examination Survey data to study the association between school lunch consumption and urinary phthalate metabolite concentrations in children (ages 6-11 years, N = 2196) and adolescents (ages 12-19 years, N = 2314). After adjustment for other covariates, children who Always consumed school lunch had significantly elevated urinary concentrations of the following phthalate metabolites compared to levels in children who Never ate school lunch: sum of di(2‑ethylhexyl) phthalate metabolites, (28% higher, 95% confidence interval, CI: 10, 49%); mono‑(carboxy‑octyl) phthalate (MCOP; 43% higher, 95% CI: 17, 76%) and mono‑n‑butyl phthalate (18% higher, 95% CI: 3.5, 34%). We did not find statistically significant associations in adolescents, but the trend for MCOP concentrations was similar to that of children. In sensitivity analyses, associations between 24-hour recall of cafeteria food and urinary phthalate metabolites were not statistically significant, which could indicate that associations observed with Always consuming school lunch are due to residual confounding. Our findings show that children who Always eat school lunch had higher levels of exposure to some phthalates, but the source of differences in exposure need to be evaluated in additional studies.

Keywords: Cafeteria; Diet; Endocrine disruptors; Exposure assessment; Phthalates; Plasticizers.

Figure 1.

Median urinary phthalate metabolite concentrations (µg/g creatinine) in children (ages 6–11) and adolescents (ages 12–19) by school lunch consumption category. Footnote: In children: n (Never) were: 184, for MCNP and MCOP, and 217 for the rest of the urinary metabolites; n (Sometimes) were: 278 for MCNP and MCOP, and 334 for the rest of the urinary metabolites; n (Always) were: 1407 for MCNP and MCOP, 1644 for the rest of the urinary metabolites. In adolescents: n (Never) were: 392 for MCNP and MCOP, and 527 for the rest of the urinary metabolites; n (Sometimes) were: 339 for MCNP and MCOP, and 471 for the rest of the urinary metabolites; n (Always) were: 1049 for MCNP and MCOP, and 1316 for the rest of the urinary metabolites. *significant p trend – Models adjusted for urinary creatinine (continuous, ln-transformed)

Figure 2.

Median urinary phthalate metabolite concentrations (µg/g creatinine) in children (ages 6–11) by school lunch consumption category over time. Footnote: MCOP was not measured in the 2003–2004 sampling cycle. n (Never) were: 33 (2003–4), 33 (2005–6), 25 (2007–8), 35 (2009–10), 37 (2011–12), 54 (2013–14). n (Always) were: 237 (2003–4), 259 (2005–6), 299 (2007–8), 305 (2009–10), 271 (2011–12), 273 (2013–14)