Food packaging and bisphenol A and bis(2-ethyhexyl) phthalate exposure: findings from a dietary intervention

Abstract

Background: Bisphenol A (BPA) and bis(2-ethylhexyl) phthalate (DEHP) are high-production-volume chemicals used in plastics and resins for food packaging. They have been associated with endocrine disruption in animals and in some human studies. Human exposure sources have been estimated, but the relative contribution of dietary exposure to total intake has not been studied empirically.

Objectives: To evaluate the contribution of food packaging to exposure, we measured urinary BPA and phthalate metabolites before, during, and after a "fresh foods" dietary intervention.

Methods: We selected 20 participants in five families based on self-reported use of canned and packaged foods. Participants ate their usual diet, followed by 3 days of "fresh foods" that were not canned or packaged in plastic, and then returned to their usual diet. We collected evening urine samples over 8 days in January 2010 and composited them into preintervention, during intervention, and postintervention samples. We used mixed-effects models for repeated measures and Wilcoxon signed-rank tests to assess change in urinary levels across time.

Results: Urine levels of BPA and DEHP metabolites decreased significantly during the fresh foods intervention [e.g., BPA geometric mean (GM), 3.7 ng/mL preintervention vs. 1.2 ng/mL during intervention; mono-(2-ethyl-5-hydroxy hexyl) phthalate GM, 57 ng/mL vs. 25 ng/mL]. The intervention reduced GM concentrations of BPA by 66% and DEHP metabolites by 53-56%. Maxima were reduced by 76% for BPA and 93-96% for DEHP metabolites.

Conclusions: BPA and DEHP exposures were substantially reduced when participants' diets were restricted to food with limited packaging.

Figure 1

Intervention study design (n = 20 individuals from five families). Each participant provided a total of six urine samples (arrows; two per phase). Paired samples collected from each individual during each phase were combined for analysis.

Figure 2

Box plots showing the distribution of urinary levels of BPA and phthalate metabolites in preintervention (Pre), intervention, and postintervention (Post) samples. Boxes represent values between the 25th and 75th percentiles; black lines inside boxes indicate medians; whiskers indicate the range of nonoutlier data points (using Tukey’s definition of outliers); and circles represent outliers. The fresh food intervention was associated with significant reductions in urinary excretion of BPA (A) and metabolites of DEHP [MEHP (B), MOHP (C), and MEHHP (D)]. No significant changes were observed in the other phthalate metabolites analyzed, although there was a small reduction in the DBP metabolite MBUP (F); concentrations of MEP (E), MBZP (G), and MMEP (H) showed little change. Compared with the 2007–2008 NHANES sample of 2,604 individuals ≥ 6 years of age (CDC 2009), the preintervention medians and 95th percentile estimates for adults and children combined were higher for BPA (A), DEHP metabolites (B–D), MBUP (F), and MMEP (H), much lower for MEP (E), and similar for MBZP (G). The NHANES median for MMEP was < LOD of 1.1 ng/mL, and the NHANES 95th percentile for MEP was 2,140 ng/mL. *p < 0.05, and **p < 0.005 for reductions or increases between intervention phases as determined by p-value for slope in the mixed-effects model.