In a large multiethnic, representative sample of US adults, we found that increasing urinary BPA levels were associated with hypertension. The observed association was found to be independent of confounding factors such as smoking, BMI, alcohol intake, diabetes mellitus, and serum cholesterol level. Our study adds to the emerging evidence of the role of environmental exposure to BPA on health outcomes in humans [8
] by being the first study
reporting an association between BPA exposure and hypertension, which is a major public health condition and a strong risk factor for CVD [12
BPA is an environmental chemical used as a constituent monomer in polycarbonate plastics, which are used extensively in drinks containers and food packaging, and in the production of oxidants used in the lining of canned goods [1
]. Exposure to BPA is believed to be mainly through dietary intake with additional exposure through water, dental sealants, inhalation of household dusts, and exposure through skin [1
]. Recent studies have documented that over 93 to 95% of the general population has measurable concentrations of BPA metabolites in urine [2
Several lines of recent evidence suggest that an association between urinary BPA levels and hypertension may be biologically plausible. Animal studies have suggested that BPA exposure may have a role in the development of hypertension thorough several mechanisms, including BPA's role in weight gain and obesity development potentially through its actions on preadipocytes [23
], role as an estrogen [5
], potential interactions with estrogen-related receptor gamma [25
], actions as a thyroid hormone antagonist [4
], role as a peroxisome proliferator-activated receptor gamma antagonist [26
], and its role in influencing pancreatic endocrine function [27
]. Alonso-Magdalena et al. [28
] in a recent experiment showed that mice exposed to long-term exposure to BPA developed hyperinsulinemia, insulin resistance, and glucose intolerance. Furthermore, BPA has been shown to induce endothelial cell injury mediated through oxidative stress [29
] and elevations in lipids [32
] in animal models. In epidemiological studies in humans, BPA levels were found to be associated with abnormal liver function enzymes, higher levels of fasting glucose, insulin, and HOMA-IR insulin resistance [8
], all are factors known to be associated with hypertension development [15
However, there are no previous studies in humans for comparison. It is in this context that our results regarding objectively measured systolic and diastolic blood pressures to define hypertension in a large sample of US adults are important. In the current study, we have demonstrated a consistent, positive association between higher BPA levels and hypertension that was independent of major confounders and also consistent in stratified analyses by race/ethnicity, BMI, and diabetes mellitus.
The main strengths of our study include its nationally representative sample, use of rigorous study methods to collect the data, and the availability of extensive data on confounders [19
]. The main study limitation is that the current study is cross-sectional in nature, making it impossible to draw cause-effects in the observed associations. Future prospective studies are required to confirm or disprove our findings.
In summary, we found that in a nationally representative sample of US adults, higher BPA levels were positively associated with hypertension independent of confounding factors such as age, gender, smoking, BMI, alcohol intake, diabetes mellitus, and cholesterol levels. If confirmed in future prospective studies, reducing environmental exposure to BPA may have a role in the prevention of hypertension.