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SKEPTOID BLOG:

The Media and the Latest BPA Scare

by Alison Hudson

October 17, 2013

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Donate Bisphenol A is back in the news again. Are you scared yet? The news media certainly thinks you should be. But we all know how dodgy science reporting in the news media is. So, should we be scared? Or is this another example of hyping scary science for link bait?

This time, BPA is being accused of increasing the miscarriage chances in women who are exposed to "elevated levels" of BPA. It has been reported in most of the major news outlets this week, many of them with scary link headlines ("Common Chemical Doubles Chance of Miscarriages!") and more reasonable article titles ("BPA May Increase Risk of Miscarriage, Study Finds"). A shocking link headline is always good for more clicks.

Here's the first thing to keep in mind about these reports (and probably any mainstream science news item you encounter): The reporters almost certainly did not read the actual study they are reporting on. They are relying on PubMed abstracts and/or press releases and/or what other news sources like the AP have already reported.

In the case of the recent BPA news, it's certain none of the reporters have seen the actual study because it isn't published yet; the study was presented at the annual meeting of the American Society of Reproductive Medicine (ASRM). Unless these science journalists were attending the ASRM conference -- and we know how heavy the press covers THAT star-studded gala! -- they are not relying on primary source information. In fact, reports from many of the major news sources -- CBS, HuffPo, The Telegraph, others -- all seem to be drawing exclusively off of the same two sources: the ASRM press release and an AP report. [Actually, many of them just reprinted or revised the AP report.]

One thing missing from these reports is actual numbers, since the ASRM release doesn't cite any. What does "significantly increased risk" actually mean? I have found different claims in different places concerning the risk of miscarriage in the U.S.; the American Pregnancy Association says it's anywhere from 10% to 25%, but up to 75% of those are chemical pregnancies, i.e. pregnancies that never really take hold in the first place and sometimes aren't even detected. I'm assuming that the BPA study didn't include those, since the women monitored were confirmed pregnancies a month or more along.

Let's say 18% overall risk of miscarriage is average, and allow for a more conservative 60% of those being chemical pregnancies. That means that about 7% risk of a "standard" miscarriage. There's no number in the ASRM press release for how much the risk has increased, but the AP Report, which has more numbers, places the risk at 80% (which some link bait headlines were interpreting as "Double the Risk!!!!"). That's about a 13% chance of miscarriage in women with elevated BPA levels.

A 13% risk of miscarriage is not an insignificant number, for sure. But we still don't know what "elevated levels" means, nor where the cutoff between "safe levels" and "unsafe levels" is. The press release itself says that the risk of miscarriage was increased for women in the "highest quartile," by which they mean the top 25% of BPA levels; but what those numbers are depends on what the median of levels measured was. Many of the reports also omitted the fact that the women in this study were recruited because they have histories of infertility or miscarriage. In other words, these women were already prone to problem pregnancies.


Am I dismissing this science? Not in the slightest. There is mounting evidence that BPA is something that should concern us. But there's a lot about this particular report that we just don't know yet. And the AP report even has one of the study authors downplaying the study's significance, noting that it was a small sample size and that the results had not yet been peer reviewed.

In this case, the science media hasn't done terribly, if these numbers are anywhere near accurate. But a broken clock is right twice a day, and lazy reporting is lazy reporting in any case. Always read beyond the scary headline take any "science news" you see in the mainstream media with a grain of salt.

by Alison Hudson

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