Monday, October 24, 2011

More BS on BPA

Gee.  By coincidence, more statistical non-sequiturs on BPA, just as the topic arose over the weekend.

A new study in Pediatrics reports a statistical association between bisphenol A (BPA) levels in a group of 244 pregnant women and increased anxiety, hyperactivity and depression in girls (but not in boys) at ages 2 and 3 as measured by parent-reported assessment on two behavioral scoring tests. BPA is used in food and beverage container linings and other consumer and medical/dental products.

Does this actually mean something?


As with any epidemiological study, the results only show a statistical association or correlation — not cause and effect. As noted by the authors, the clinical relevance of the findings is unclear, meaning that there is no claim that the children exhibited abnormal levels of anxiety, depression or hyperactivity behavior.

Matter of fact, boys' behavior was should BPA be prescribed for boys, not girls?

As the authors noted, they made many comparisons and never applied the standard mathematical correction process for multiple comparisons, likely because none of their comparisons would have been significant if they had done so. In short, it is uncertain if any of the claimed statistical associations would have been significant if proper statistical procedures had been applied.

And the hammer goes down here:

[...]  the most relevant human study, that of Teeguarden et al. (Toxicological Sciences, vol. 123, pages 48-57, 2011), which found no free (biologically active) BPA in the blood of 20 volunteers who consumed a diet that contained BPA at a level greater than the 95 percentile level of the US population as measured by the CDC NHANES biomonitoring survey. 

If there is no free-BPA in the blood, then there is no free-BPA to cross the placental barrier and interact with neuro-behavior receptors in the developing human embryo. So BPA cannot be the cause of the changes in behavior — positively or negatively — in 3-year-olds. Based on the results of Teeguarden et al., the statistical associations observed by Braun et al. are not biologically plausible.

The presence of BS does not necessarily indicate the presence of facts.


jfields said...

That makes complete sense!J.

Anonymous said...

And here I thought you were an advocate for the unborn?

Tim Morrissey said...

Correlation and cause...the bugaboo of the media. But, like the "cell phones cause brain cancer" theme, they'll keep doing studies until they "prove" it....

Anonymous said...

"If you've paid attention, you'll remember that Fenton Communications is the outfit supplying the Milwaukee JS with content about Bisphenol-A. The JS has swallowed their crap hook, line, and sinker, despite significant and dispositive evidence that the entire campaign is .........well.......bull****"

And you'll also recall the numerous companies fronting the author of Junk Science, who has his own agenda for discrediting BA-P.

Regardless of the money behind the sources, in looking at the overall scope of the research, a number of independent scientists have drawn more consistent conclusions as to the impact of BA-P.

Of course industry sponsored studies will claim little or no harmful effects, that's not surprising!


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