In this study, we developed an intervention strategy comprising dietary, lifestyle habit, and environmental components. This intervention strategy involved repeated and voluntary self-restraining components aimed at reducing urine phthalate concentrations during pregnancy. The decline in the urinary concentrations of the 10 phthalate metabolites measured implied that our intervention approach efficiently reduced the exposure of the participants to PAEs.
Dietary is the primary route for intake of phthalates, and studies conducted in Canada (Pacyga et al., 2019) and the US (Koch et al., 2013) showed detectable concentrations of phthalates in fast foods such as french fries, hamburgers, and sandwiches). Among these fast foods, hamburgers exhibited the highest PAEs concentration. According to previous study, the consumption of more fresh vegetables, fruits, nuts and fish is associated with low exposure to phthalates (Bai et al., 2015). Therefore, our diet in the intervention strategy restricted participants from eating fast-foods and encouraged them to consume healthy foods. Our results demonstrated that the concentrations of MnBP, MEHHP and MEOHP significantly declined after the 1st intervention, with the decrease reaching 40% after the 3rd intervention. These findings are consistent with those of Rudel’s (Rudel et al., 2011) and Sathyanarayana’s (Sathyanarayana et al., 2013) studies, in which phthalate metabolites were significantly lowered after the diet of participants was restricted to foods involving limited packaging. However, these studies involved complete diet replacement. In contrast, in our study, the participants were advised to pursue a self-guided intervention. Therefore, although our study did not involve a complete replacement intervention, the repeated remind through written recommendation appeared to exhibit similar effectiveness.
According to an intervention study by Barrett (Barrett et al., 2015), the MMP and MiBP concentrations showed no appreciable change across three time periods. In fact, after a 3-day dietary intervention, the mean concentrations of MiBP were 15.9, 24.0, and 23.7 ng/mL for the pre, mid, and post-intervention periods, respectively. The corresponding MMP concentrations for the three periods were 19.4, 24.6, and 27.5 ng/mL. However, in a study involving a school for girls in Taiwan reported reduction in MiBP, MEP and MMP through an intervention strategy (Chen et al., 2015). A possible reason for the inconsistency of results from different studies is that most interventions involve a simple dietary change, whereas the underlying intervention strategy requires avoiding foods in plastic containers and using less personal care products such as shampoo and shower lotion. Many studies have also demonstrated that besides ingesting of contaminated foods, dermal absorption from personal care products is another route for human intake of phthalates (Valvi et al., 2015; Wenzel et al., 2018). In the present study, after the pregnant women decreased their usage of personal care products such as hair dye, shampoo, perfumes, body lotions, and nail polish, the concentration of MiBP and MMP significantly declined after the 2nd intervention, reaching 50% after the 3rd intervention. These results suggest that some LMWPs could be reduced through our intervention strategy.
However, after the 3rd intervention, MBzP showed no statistically significant changes, although this may be related to its concentration of less than 10 ng/mL from the baseline to the end. We also observed that MEHP changed sharply, reducing by approximately 30% in the fifth month of antenatal examination, and reducing a 60% decline in the seventh month antenatal. These results are similar to those of a two-week randomized dietary trial by Sathyanarayana, with MEHP geometric means of 3.9, 4.1, and 4.2 ng/mL for the baseline, during the intervention, and post intervention periods (Sathyanarayana et al., 2013), This response is possibly because of the complex, dynamic, multidimensional characteristics of the DEHP metabolite. The DEHP can initially be metabolized to MEHP, followed by MEHP metabolizing to the secondary mono-phthalate easters including MEHHP, MECPP and MEOHP (Minatoya et al., 2017). Notably, in our study, the ΣDEHP, ΣLMWP, andΣ10PAEs significantly declined after the 1st and subsequent interventions. This is consistent with (Ackerman et al., 2014)), who reported that through a dietary intervention, the GM concentrations of BPA reduced by 66%, while those of DEHP metabolites decreased by 53‒56% (Ackerman et al., 2014).
The environment is another factor associated with PAEs exposure. According to previous studies, MEOHP and MEHPP were higher among women who do smoke compared to non-smokers (Cantonwine et al., 2014). In the present study, after 1st intervention, MEOHP and MEHPP declined significantly, and this may be partially attributed to the avoidance of second-hand smoke. We also encouraged the participants to undertake limited transportation by car. Owing to the elevated internal temperature of the cabin of a car or truck, the vinyl interior trim of some vehicles can deteriorate and decompose, thereby releasing of phthalate particles (Rakkestad et al., 2007).
In addition, we recommended adequate exercise, such as walking and yoga, to the pregnant women. According to a study in Australian, slightly higher total phthalate metabolite concentrations were associated with insufficient activity (Bai et al., 2015) . Further investigation is warranted to better understand the link between physical activity and low phthalate ester levels biologically.
In this study, an intervention strategy for reducing the PAE concentrations in pregnant women is introduced. This strategy comprises eight components associated with diet, lifestyle and the environment. This approach closely parallels real life compared to studies focusing on intervention involving just one component. Moreover, repeated intervention and measures are better for evaluating the efficiency of the intervention strategy. However, the present study involves several limitations that require attention. First, the intervention components were not distinguished to clarify their impact on the phthalate reduction efficiency. Considering that some intervention components are clustered, determining the contribution of each component to the phthalate concentrations reduction was not achieved. Second, some findings may be biased because of the relatively small sample size. However, the longitudinal sampling involved in the present study allowed individuals to serve as their controls, thereby avoiding the many sources of confounding information that limit cross-sectional studies. Finally, because the participants in this study are from a moderate economic city in Hubei province, China, generalizing the study efficiency to other countries and socioeconomic groups may be limited.