BPA, Chemical Used to Make Plastic Bottles, Linked to Increased Death Risk

Bisphenol A (BPA), an industrial chemical used to make items such as plastic bottles, has been linked to a greater risk of death in a study.

BPA is used to make certain types of plastics and resins, which make up parts of some bottles, sports equipment, medical devices, water pipes, the lining of food and drink cans, and thermal paper used in sales receipts. In the U.S., 12 states and Washington D.C. have restrictions on BPA. But, according to existing research cited by the authors of the paper published in the journal JAMA Network Open, 90 percent of urine samples of the general populations in the U.S. contain traces of BPA.

The new study involved 3,883 adults in the U.S. aged 20 or over who were taking part in the U.S. National Health and Nutrition Examination Survey 2003-2008. The participants provided samples of their urine, and gave information including their age, sex, race, diet, and exercise levels.

Of the total volunteers, 344 died 10 years after the study started, including 71 from cardiovascular disease, and 75 from cancer.

Dr. Wei Bao Department, assistant professor in the College of Public Health at University of Iowa and colleagues found that those who had higher levels of BPA in their urine had a greater risk of dying by the end of the study.

Participants with the highest levels of BPA had a 51 percent higher risk of death from any cause. The link remained when the researchers accounted for factors that might put a person at higher risk of dying, they said.

Participants who had higher levels of BPA were more likely to be younger, male, black, have lower educational levels, and lower family income. They were also less likely to exercise, but ate more, had a poor diet, and a higher BMI than others.

The team said their findings reflect past studies which have linked BPA exposure with a risk of cardiometabolic disorders such as diabetes, high blood pressure, and cardiovascular disease.

More research is needed to replicate the findings in different populations and to explain the link, the authors said.

Kevin McConway, emeritus professor of applied statistics at The Open University, who did not work on the paper, said in a written statement: "This research used data from quite a large sample of Americans, that is generally representative of the U.S. adult population. But it's an observational study, and there are always issues in deciding what the results of observational studies actually mean."

McConway said: "Though the researchers found that (generally) the higher the urinary BPA level, the higher was the risk of death at a given time, this doesn't mean that it is the BPA in the participants' bodies that was causing the increased risk."

He said "the big snag" is that researchers can't adjust their data for every potential variable that may skew the results.

Ieuan Hughes, emeritus professor of paediatrics at the University of Cambridge, said looking at all types of death, or all-cause mortality, is a "blunt instrument."

"Much of the literature on the toxic effects of BPA, a chemical which is ubiquitously present in all ages including the fetus, has focused on endocrine-related effects in animals and in humans. For example, male reproductive disorders. But how can that be teased out in terms of mortality?

He said: "Cleansing the environment of BPA has started (witness BPA-free products on supermarket shelves) and the use of substitute analogues such as bisphenol S. The authors' call for further studies are indeed warranted as humans will long remain exposed to this class of chemicals."

Dr. Fred Davis, associate professor in organic chemistry at the University of Reading who also did not work on the paper, said: "This paper will add to a growing body of concern about the safety of polymers containing the monomer BPA."

Davis said: "Over the last few years, it has found that very small quantities of BPA are present in most people. This exposure is thought to be due to the use of BPA containing polymers in contact with food, in for example, plastic containers or coatings for cans. The exposure then occurs either due to the presence of unconverted monomer, or by decomposition (probably hydrolysis) of the polymer.

"The levels of exposure to this material is low and consequently this is challenging to investigate in terms of the hazards, particularly in view of the many overlapping factors that may influence mortality. Thus, the conclusions reached here rely on the models used, and despite a relatively large sample in research conducted over 10 years the authors concede more studies are needed."