Let me state up front that I have no doubt BPA — a chemical used in the manufacture of many modern goods, including in the past many water bottles and sippy cups — is something we should get rid of in any connection to food. But at the same time, I have to speak out when a scientific study’s findings are misused to forward political agendas.
The findings here come, once again, from the journal Pediatrics. It seems like a month doesn’t go by when this journal is publishing more crappy science, and then draping it in a public relations campaign that gets everyone’s attention. (Actually, to be fair, the science is sometimes fine; it’s the over-reaching conclusions drawn by the researchers and the PR media machine that is truly vomit-inducing.)
In this case, the researchers set out to followup on a previous study that found higher gestational (in the womb) BPA levels increased hyperactivity and aggression scores in 2-year-old girls. They wanted to determine if these findings continue as the children age, whether executive functions were impacted by higher BPA levels, and whether it was gestational BPA as opposed to childhood BPA levels that were more important.
So the researchers, led by Joe Braun, set out to test 3-year-olds, using two parental assessments — one for emotional development, and the other for executive functioning.
What they claimed to have found — and what everyone is publicizing — is this:
With adjustment for [confounding factors], each 10-fold increase in gestational BPA concentrations was associated with more anxious and depressed behavior on the BASC-2 and poorer emotional control and inhibition on the BRIEF-P. The magnitude of the gestational BPA associations differed according to child gender; BASC-2 and BRIEF-P scores increased 9 to 12 points among girls, but changes were null or negative among boys.
What does that mean, a 9 to 12 point difference? Let’s put these results into perspective. A 9-point difference is not considered significant on the two measures used. You need a 10-point difference to achieve clinical and statistical significance for each measure, something the researchers gloss over when discussing their conclusions. (The 10-point number doesn’t come from out of the air — it’s the number the publisher of these measures defined from their own normative psychometric research on the tests.)
What their data tables actually show demonstrates the problem in crystal clear numbers. Look at the two data tables below. How many numbers do you see in the 4 columns (2 in each table) where the number is 10 or greater?
If your answer is 2, you would be correct.
Another, perhaps more accurate way of summarizing the results of this study might be: In a measure of a total of 22 factors (11 subscales for girls, 11 subscales for boys), the researchers found nothing significant in 20 of those factors. Two factors — anxiety and depression in girls — were slightly elevated and would be considered in the “at-risk” range. That is, these girls might be at a slightly-elevated future risk for these two concerns based upon this data.
But the whitewashing is even better than that, because this is only for those mothers who had a 10-fold increase in the gestational BPA levels. The entire childhood BPA levels of the children followed in the study found nothing of significance to note.
None of this stops the researchers from drawing some conclusions from their almost-significant data, such as these sentences from the study:
In particular, gestational BPA exposure was associated with higher scores for measures of anxiety, hyperactivity, emotional control, and behavioral inhibition.
The results from analyses using the BRIEF-P corroborated our ï¬ndings with the BASC-2 and suggest that associations between gestational BPA exposure and behavior might be related to poor behavioral regulation.
Maybe, maybe not. Since the researchers didn’t find actual clinical significance in the BRIEF-P, it would be hard to draw conclusions from it. And look at those data tables again — does hyperactivity, emotional control or behavioral inhibition reach the 10-point cut-off? Nope.
All in all, I’m again disappointed in the journal Pediatrics. Here’s a study that looked at a total of 44 variables (when you count the analysis of gestational BPA versus childhood BPA levels) and found significance in only 2 of them.
To me, that’s an interesting correlation. But it’s not this earth-shattering news that helps us really put an end to BPA, now is it? Instead, it’s a marginal datapoint that could almost be used to suggest the opposite of the researchers’ conclusions.
I think it’s a no-brainer to take BPA out of our food supply chain. Why take the risk when alternatives are available? But we’re not going to do it with trumped up studies such as this.
Read the full story: BPA Prenatal Exposure Linked to Behavioral Problems in Kids
Read the full study here: Impact of Early-Life Bisphenol A Exposure on Behavior and Executive Function in Children
5 comments
Dr. Grohol, given how exercised you already are from the Pediatrics article, I urge you to read the following quote from the study only while doing transcendental meditation or under heavy sedation: “We examined the P-values for this interaction term and considered values of <.10 to be indicative of modification, because our statistical power was limited by sample size."
Let me paraphrase: These researchers jettisoned the traditional, highest acceptable p-value for statistical significance, .05, because the combination of small sample size AND small effect size AND a standard of .05 in their study would have rendered their findings non-significant, their hypothesis unconfirmed, and their study unpublishable.
If these researchers had been District Attorneys would they have dared address the Court: "Your Honor, due to our not being able to gather sufficient evidence, we are not able to meet the traditional burden of 'proof beyond a reasonable doubt'. But surely, your Honor, you have no objection to substituting a lesser standard in this case. Yes, yes, we realize that perhaps an innocent man will be found guilty as a result, but…."
How can it be that what would be a farcical proposal in a judicial setting is Standard Operating Procedure in a scientific one?
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Barth…. Thank you and good catch — something I missed (and of course, just naturally assume that researchers use the accepted standard of 0.05 and not make up their own “new” standard).
Which means this data and finding is even weaker than I suggested above.
I believe the peer reviewers at Pediatrics are either asleep at the proverbial wheel, or the editors simply don’t care about their journal’s reputation any more. Astounding.
Dr. What is BPA,is it posible that you could use complete words or explain what the letters stand for,Thank you yours truly manuela
Maya: Bisphenol A (BPA). FOUnd in many plastics, among other things. Can leach into food when microwaved.
Another great post about junk science. I read another article recently that stated in the Methods that they “randomly selected” and in the SAME SENTENCE admitted they gave only females the particular test they were examining for effectiveness due to “evidence that women perform better with that kind of measure.” Are you kidding me? How is this stuff being published? That particular article was forwarded to all mental health providers doing work with a large county in California, seemingly to promote the use of this kind of therapy with a specific diagnosis. Unbelievable.
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