Higher BPA exposure tracked with higher estrogen and progesterone in women

By Dr. Sanchari Sinha Dutta, Ph.D.Reviewed by Lauren HardakerAug 24 2026

Everyday exposure to plastics, packaged foods, bottled drinks, and cosmetics may be shaping hormone patterns in ways researchers are only beginning to understand.

Study: Exploring the association between environmental exposure to phthalates and bisphenol A and changes in reproductive hormones in women: a cross-sectional study. Image Credit: monticello / Shutterstock

Higher urinary concentrations of bisphenol A and several phthalate metabolites were positively associated with serum estrogen and progesterone concentrations in premenopausal Iranian women, according to a new study accepted for publication in the journal Scientific Reports.

Background

Endocrine-disrupting chemicals (EDCs) are external substances that can interfere with the body’s endocrine system, disrupting normal hormone signaling and function. These chemicals can enter the body through the skin, lungs, and the digestive system.

Bisphenol A (BPA) and phthalates are widely encountered EDCs found in a range of everyday products. These chemicals are widely used in plastic manufacturing, food processing, personal care products, children’s toys, and construction materials. Environmental exposure to these chemicals has been associated with adverse effects on the cardiovascular, respiratory, nervous, reproductive, and immune systems, as well as endocrine disruption.

Studies focusing on reproductive functions have indicated that EDCs can mimic or block normal functions of key reproductive hormones and have been linked to impaired ovulation, menstrual irregularity, adverse pregnancy outcomes, development of uterine fibroids, and infertility.

The current study aimed to explore whether environmental exposure to BPA and phthalates was associated with circulating levels of the reproductive hormones estrogen and progesterone.

Study design

A total of 90 Iranian premenopausal women from Ilam province were enrolled in the study. Based on self-reported information on environmental and lifestyle-related chemical exposure, participants were categorized into the exposed (higher probability of exposure) and control (lower probability of exposure) groups. Classification reflected the overall pattern of exposure-related behaviors rather than a numerical exposure score.

Spot urinary samples were collected from participants to measure BPA and phthalate metabolites, and serum samples were collected to measure estrogen and progesterone.

Key findings

The analysis of urinary metabolites revealed that more than 94% of participants in the exposed group had detectable levels of all measured urinary phthalate metabolites, while BPA was detected in 100% of participants. Detection was also common in the control group, with most phthalate metabolites detected in more than 95% of participants.

Median urinary levels of BPA and most measured phthalate metabolites were significantly higher in the exposed group compared to the control group. Similarly, participants in the exposed group had higher median serum levels of estrogen and progesterone than those in the control group.

Regression analyses identified positive associations between urinary concentrations of ΣDEHP, MEP, MBP, and BPA and serum estrogen levels. Mixture analysis also identified positive associations involving BPA, MBP, and ΣDEHP.

Similarly, a significant positive association was observed between urinary levels of MBP, mono-ethyl phthalate (MEP), and BPA and serum progesterone levels. The modeling also indicated an overall positive association between higher combined BPA and phthalate biomarker concentrations and both hormones.

The researchers also examined whether behaviors such as drinking bottled water or other beverages, eating ready-to-eat foods, and using cosmetics were associated with differences in these exposure-hormone associations. However, these stratified findings were not uniformly consistent across metabolites and hormone outcomes.

Study significance

The study found that higher urinary concentrations of several phthalate metabolites and BPA are associated with higher circulating levels of estrogen and progesterone in the women studied. Changes in estrogen and progesterone homeostasis could have implications for reproductive health, although the study did not directly assess reproductive outcomes.

The researchers reported that urinary concentrations of most measured phthalate metabolites and BPA in this study population were higher than levels reported in previous general-population studies. Such elevated biomarker concentrations may be attributable to recent changes in dietary habits, such as increased reliance on ready-to-eat foods packaged in plastic containers.

Furthermore, the authors cite reports that describe Iran as the second-largest consumer of cosmetics in the Middle East, suggesting the possibility of elevated exposure due to the widespread use of cosmetics and personal care products.

Previous studies investigating the association between EDC exposure and reproductive hormone levels have produced mixed results. Some studies have found positive associations between BPA and phthalate exposure and circulating estrogen and progesterone levels, while some studies have reported negative or no significant associations.

These discrepancies between current and previously reported findings may be attributable to differences in government policies regulating the use of BPA and phthalates in everyday products, or to geographic, social, cultural, and dietary differences among populations.

Methodological variations, such as timing of sample collection and laboratory methods used for quantification, as well as differences in population characteristics, may also potentially contribute to inter-study heterogeneity.

Notably, the current study analyzed associations involving combined exposure to several phthalate metabolites and BPA and reproductive hormone levels. The authors state that, to their knowledge, this is the first study to examine these co-exposure associations with estrogen and progesterone concentrations in Iranian women.

Overall, these findings highlight the need for greater public-health awareness of potential BPA and phthalate exposure in Iran and may help inform future regulatory and healthcare strategies.

Because the research used a cross-sectional design, it cannot establish causality or assess long-term changes in exposures and outcomes. Furthermore, the study relied on self-reported information on environmental and lifestyle-related chemical exposure, which may introduce recall bias and increase the possibility of exposure misclassification. A single-spot urine sample was also used, which may not accurately reflect longer-term exposure because BPA and phthalates are rapidly metabolized.

The study was conducted on a relatively small sample of premenopausal women from one Iranian province, which may limit the generalizability of its findings to other populations. Residual confounding by unmeasured exposures cannot be ruled out, and the authors caution that the BKMR mixture findings should be considered exploratory and hypothesis-generating rather than confirmatory. Larger-scale, longitudinal studies involving demographically diverse populations are needed to validate these findings, better assess temporal relationships, and strengthen causal inference.