After months of dominating the health headlines, it seemed that BPA, or bisphenol A, had taken a backseat to more pressing health concerns. But the plastic softening chemical is back in the news with a study that found that exposure to BPA from cans or plastic bottles can lead to a sudden increase in blood pressure.

Over the years, BPA has been linked to everything from childhood obesity, to diabetes, to impaired liver function. But much of this research has been conducted using data from large population studies. Thus, researchers can distinguish trends linking BPA to health conditions, but they don't provide evidence that BPA is the cause. But the new study — conducted by randomized control trial — has found that a single exposure to BPA can have a direct and immediate impact on cardiovascular health.

For the study, which was published in the journal Hypertension, researchers recruited 60 older participants, most of whom had never had issues with high blood pressure (although some did.) They asked the participants to drink soy milk from either a can or a glass bottle on three separate occasions, spaced apart by several weeks. The researchers chose soy milk because it does not have any effect on blood pressure and it is also fairly neutral in terms of leaching BPA from can or bottle liners, according to The New York Times.

The research team from Seoul National University’s department of preventive medicine in Korea found that when the participants drank soy milk from a can, their urine levels of BPA rose almost instantly — and so did their blood pressure. But when the same people drank the same beverage from glass bottles, which don’t use BPA linings, their BPA levels and blood pressure remained unchanged. 

The research did not look at how long BPA levels remained elevated, but the authors did raise the concern that even a short increase in blood pressure — repeated several times a day through BPA exposure in drinks and food containers — could have lasting effects on cardiovascular health. 

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