Unexpected results in a randomized dietary trial to reduce phthalate and bisphenol A exposures

Abstract

Diet is a primary source of exposure for high-molecular-weight phthalates and bisphenol A (BPA), but little is known about the efficacy of various interventions to reduce exposures. We conducted a randomized trial with 10 families to test the efficacy of a 5-day complete dietary replacement (Arm 1; n=21) versus written recommendations to reduce phthalate and BPA exposures (Arm 2; n=19). We measured phthalate and BPA concentrations in urine samples at baseline, intervention, and post-intervention periods. We used Wilcoxon paired signed-rank tests to assess change in concentrations across time and multi-level mixed effects regression models to assess differences between Arms 1 and 2. Urinary di(2-ethylhexyl) phthalate (DEHP) metabolite concentrations increased unexpectedly from a median of 283.7 nmol/g at baseline to 7027.5 nmol/g during the intervention (P<0.0001) among Arm 1 participants, and no significant changes were observed for Arm 2 participants. We observed a statistically significant increase in total BPA concentration between baseline and intervention periods in Arm 1 but no significant changes in Arm 2. Arm 1 food ingredient testing for DEHP revealed concentrations of 21,400 ng/g in ground coriander and 673 ng/g in milk. Food contamination with DEHP led to unexpected increases in urinary phthalate concentrations in a trial intended to minimize exposure. In the absence of regulation to reduce phthalate and BPA concentrations in food production, it may be difficult to develop effective interventions that are feasible in the general population. An estimate of DEHP daily intake for children in the dietary replacement Arm was above the US Environmental Protection Agency oral reference dose and the European Food Safety Authority's tolerable daily intake, suggesting that food contamination can be a major source of DEHP exposure.

Daily diet containing canned products significantly increases serum concentrations of endocrine disruptor bisphenol A in young women

“…It is worth noting that during the intervention none of the women had dental sealants placed, nor did they change their lifestyle in a way that could have been additional source of BPA exposure. Our results, supported also by other studies, 11,12 are alarming, especially considering the fact that BPA is an environmental estrogen, and it is likely that constant exposure even to low doses may disrupt the action of endogenous hormones.…”

Developing an intervention strategy to reduce phthalate exposure in Taiwanese girls

“…However, it is difficult and impractical to attempt to provide phthalate-free food to participants. Like Sathyanarayana et al (2013), we could easily end up with contaminated food that biases the interpretation of our results. Moreover, as the 2011 Taiwan food scandal demonstrated, finding phthalate-free food may be impossible: five major food categories in Taiwan had been phthalate-tainted for at least two decades (Yen et al, 2011).…”

“…Rudel et al (2011) conducted a full dietary intervention in five families and found significant reductions in their urinary phthalates when they stopped eating foods prepared or stored in plastic containers. Sathyanarayana et al (2013) tried a complete dietary replacement to reduce exposure to phthalates, but they failed because the replacement food was contaminated with DEHP. They found that written recommendations to prevent dietary contamination caused by plastics were insufficient to help people reduce their exposure to phthalates.…”

Estimating bisphenol A exposure levels using a questionnaire targeting known sources of exposure

“…While some studies indicate that diet accounts for more than 90 % of potential BPA exposure in the environment of the general population (50,73) , other studies have found that diet explains a significantly lower proportion of urinary BPA levels (44,47,48,108) . Intervention studies have demonstrated the ability to lower, but not eliminate BPA exposure among study participants (50,59,71,109) . In the current study, only recent canned food intake, as (a) urinary BPA levels compared with reported canned food intake on the BEAM (r = 0·19, P = 0·14); (b) urinary BPA levels compared with reported canned food intake on 24 h food records (r = 0·35, P = 0·004); (c) urinary BPA levels compared with BEAM score (r = 0·26, P = 0·03); (d) urinary BPA levels compared with food record score (r = 0·32, P = 0·008).…”

“…However, a more recent study did not observe the expected decrease in urinary BPA levels when packaged foods were removed from study participants' diet (71) .…”