A small, unproven study raised concerns this week that the plastic additiveBisphenol A, better known as BPA, causes miscarriage. The researchers suggested pregnant women take extreme steps to avoid BPA, even though earlier studies have found the amount of the chemical in the average American diet is safe.
The study was presented by StanfordUniversity researcher Ruth Lathi on Monday at the annual meeting of the American Society for Reproductive Medicine. In September, the group issued a broad-brush statement against toxic agents in the environment, calling on manufacturers to prove the safety of new chemicals before they hit the market.
Based on the study’s results, Lathi recommended that pregnant women avoid drinking bottled water, eating canned food, and touching cash register receipts. Her study measured BPA levels in the blood of 114 pregnant women and found that the women with the highest levels of BPA had the greatest incidence of miscarriage.
But several factors weakened the study’s credibility as a warning bell for all pregnant women. First, the research was not designed to determine what caused the miscarriages of 68 women in the study group. The participants were all women with a history of infertility or miscarriage, putting them at a higher risk of miscarriage to begin with. The researchers did not investigate any other possible causes of the women’s miscarriages outside of BPA exposure.
Also, while the study reported women with high BPA levels had an 80 percent greater risk of miscarriage than women with low levels, the margin of error was high. The actual risk for those women could be anywhere between 14 percent and 296 percent greater.
The results also have not yet been published in a scientific journal, which uses a peer-review process to vet the validity of scientific claims before publication. It’s unclear how much review Lathi’s study received prior to going public.
The findings contradict multiple studies and reviews of BPA by theFood and Drug Administration that have found low-level exposure to be safe for mothers and babies. A study by the National Center for Toxicological Research found that BPA was not passed from rodent mothers to babies even when the mothers were given doses 1,000 times higher than the amount normally found in foods.
Trevor Butterworth, who has covered BPA extensively for Forbes, said the study results were most likely a fluke or a meaningless correlation: “Given that we’ve been treated to many such studies where a shocking correlation is generated by limited data, this study deserves much more careful scrutiny than it has otherwise received before warning women to avoid eating tinned food.”