Monday, June 16, 2008

Stop worrying and learn to love the chemicals

Well Margaret Wente is at it again. In a column last week titled Yellow duckies and other killers, she claims that "Mothers across Canada have been prostrated by the plastics scare."
It's hard to be a good mother these days. Deadly perils lurk everywhere. Take that yellow bathtub ducky, contaminated with a dangerous substance known as BPA.
But why stop there? Wente proceeds to list other putative hazards: toxic mould, pesticides, perfumes, "death-rays from the sun", walking barefoot in the grass. The message is clear: stop worrying already!
We forget how negligent our own parents were. They gave us naked sunbaths and let us suck on plastic duckies and roll around on pesticide-drenched lawns. It's astonishing how ignorant they were, and how many of us managed to grow up.
Now Margaret Wente is no scientist (what was your first clue?), so she needs an outside authority:
Dr. Elizabeth Whelan is president of the American Council on Science and Health [ACSH], an independent group devoted to accuracy in health reporting. She points out that both BPA and phthalates have been studied intensively for decades. There are no studies - none - that show any link between these substances and harm to people. The basis for the claims of danger are all from studies done on rats, and they don't predict human risk.
According to Media Transparency, ACSH haven't disclosed their corporate donors since the early 1990's, but their 1991 annual report listed each of the following as contributing at least $15,000:
American Cyanamid Company * Anheuser-Busch Foundation * General Electric Foundation * Rollin M. Gerstacker Foundation * ICI Agricultural Products, Inc. * ISK Biotech Corporation * Kraft, Inc. * Monsanto Fund * The NutraSweet Company * John M. Olin Foundation, Inc. * Pfizer, Inc. * Sarah Scaife Foundation Incorporated * The Starr Foundation * Archer Daniels Midland Company * Carnation Company * Ciba-Geigy Corporation * Ethyl Corporation * Exxon Corporation * General Mills, Inc. * Heublein Inc. * Hiram Walker-Allied Vintners * Johnson & Johnson * Kellogg Company * The Esther A. and Joseph Klingenstein Fund, Inc. * Malaysian Palm Oil Promotion Council * National Starch and Chemical Foundation, Inc. * PepsiCo Foundation Inc. * Union Carbide Corporation
The under-$15,000 list continues on, listing all kinds of industrial, pharmaceutical, and food corporations.

Figures don't lie ...

In her April 19th column, Wente quoted an organizations called the Statistical Assessment Service (STATS) who similarly dismiss concerns about BPA. While they don't accept industry money, STATS is funded by a number of the same conservative organizations as ACSH. I think I see a pattern here.

But so what if these organizations get "conservative" funding? An anonymous commenter on my previous post wrote:
Why should the funding source matter? Isn't it the quality of the evidence and the arguments made? Your smear is the equivalent of an ad hominem attack.
My response:
I don't think it's ad hominem. If a medical study was funded by a pharmaceutical company, I'd like to know that. Not that it invalidates the study: as you say, the quality of the evidence and the arguments (analyses) made is centrally important.
So let's have a closer look at the quality of the evidence and arguments in one particular case.

I looked at a recent post on the STATS blog concerning formula- versus breast-feeding. While the author allows that "Yes, there is robust evidence that nursing reduces ear infections [otitis media] and diarrhea", he sets out to discredit claims of a link between formula feeding and diabetes, leukemia, and serious respiratory infections. In the latter case, he writes "The most recent research does not support the contention that formula carries a higher risk," citing a 1995 paper from the Journal of Pediatrics.

Interestingly enough, that study was supported in part by the Mead-Johnson Nutritional Group. Leaving that aside, however, here are some results from the abstract:
In the first year of life the incidence of diarrheal illness among BF [breast fed] infants was half that of FF [formula fed] infants; the percentage with any otitis media was 19% lower and with prolonged episodes (>10 days) was 80% lower in BF compared with FF infants. There were no significant differences in rates of respiratory illness; nearly all cases were mild upper respiratory infections. ... These results indicate that the reduction in morbidity associated with breast-feeding is of sufficient magnitude to be of public health significance.
Sure enough, they didn't find statistically significant differences in rates of respiratory illness. Now an important consideration in statistics is the power to detect differences, which is determined by a number of factors including sample size. So what was the sample size in this study?
... morbidity data were collected by weekly monitoring during the first 2 years of life from matched cohorts of infants who were either breast fed (N = 46) or formula fed (N = 41) until at least 12 months of age.
So there were a total of 87 infants. In their discussion, the authors write:
We did not observe any significant differences in the incidence or prevalence of respiratory illnesses between BF and FF infants. However, the vast majority of episodes were mild upper respiratory illnesses. Previous studies have indicated that the protective effect of breast-feeding is greatest for lower respiratory illnesses. The sample size in our study was not large enough to detect differences in more severe respiratory illnesses.
Blind trust?

Ultimately, we all have to rely on some surrogate measures to judge the quality and trustworthiness of the information we encounter. Our own expertise can only be so broad and we rely on others to help us interpret the world. Oldly enough the words of Ronald Reagan come to mind: "Trust, but verify."

Labels: , , , , , , , , , , , ,

Bookmark and Share

4 Comments:

Anonymous Trevor Butterworth said...

A couple of points: you could read the risk assessments on BPA conducted by the European Food Safety Agency (no risk), Japanese government (no risk), CERHR in the U.S. (mostly no risk, some concern) or the recent NSF international risk assessment done by California EPA toxicologist Calvin Willhite (no risk). Moreover, you could also have noted that Wente, I believe, talked not just to STATS but to Willhite, who is highly respected among toxicologists in the U.S. Either way, in my interview with Wente, I urged her to read all the above risk assessments. Their consensus is remarkable and remarkably at odds with the activist claims about the risks of BPA.

As for the case against formula, let me clarify, for the benefit of your readers, that the article I linked to in my blog posting was written by my colleague, Dr. Rebecca Goldin, a prize winning mathematician who teaches at George Mason University, Dr. Andrea Foulkes, a biostatistician at U.Mass, and Dr. Emer Smyth, a professor of pharmacology at U.Penn. All breastfed their children; but all were outraged by a the claims and the science used to support a government campaign in the U.S. which equated using formula to the risks of smoking. Dr. Goldin has continued to look at the statistics behind other formula/breast feeding claims in a couple of other articles (linked to at www.stats.org)

I'm not sure what the exact point is that you are trying to make about STATS' analysis of this issue in relation to our writing about BPA: in both cases we are simply pointing out what the media has failed to tell the public in covering each issues, and how that failure has made them, effectively, partisans for one cause or side of the story. In the case of BPA, the weight of evidence is overwhelmingly against they're being a risk, and the claims of critics of BPA falter on the fact that oral exposure removes any estrogenic effect of the chemical whereas injection doesn't. While all of us at STATS support breastfeeding in principle, mothers who can't breastfeed shouldn't be made to feel that they are damaging their children if they use formula. Formula has changed in composition since many of these scare studies were conducted.

The reality of science and medicine is that there is not a well of pure money to foot the bill for research. But there are objective criteria and outside monitoring to determine what counts as persuasive evidence. It's easy for the press to focus on who pays for what (while turning a blind eye to the vested interests activists have in promoting a scare - they are businesses too), because they never have to deal with the dirty work of trying to understand what has really been said in the science.

Given the egregious journalistic failures - especially in the Canadian media - to tell readers honestly and dispassionately about the research into BPA, I find your outrage at Ms. Wente misplaced. Group think is not the same as the weight of evidence.

Regards
Trevor Butterworth

7:58 AM, June 17, 2008  
Blogger Nick Barrowman said...

Mr Butterworth,

Thanks for your comments.

There remains considerable uncertainty about the effect of BPA on humans and about what would be a safe level of exposure (e.g. a “tolerable daily intake”). Toxicologists continue to investigate these questions and don’t all come to the same conclusions, which is clear from examining the reports you cite. This is to be expected in science. But selective quoting of scientific findings and opinions is something else entirely. As you say, “Group think is not the same as the weight of evidence.”

You note that “It's easy for the press to focus on who pays for what”, yet Wente didn’t even hint that her sources weren’t exactly funded by “a well of pure money”. That’s what I’d call an “egregious journalistic failure”.

1:14 PM, June 17, 2008  
Blogger Trevor said...

Good data is good data; well designed studies are well designed for objective reasons. And it is on these grounds that one can state with considerable confidence that there isn't much of a debate within science about the safety of BPA. It has been repeatedly studied in risk assessments around the world, and those risk assessments all reach the same conclusion: the objection by scientists like Frederick Vom Saal are wrong: BPA loses its estrogenic capacity in humans when orally ingested. If you read the risk assessments, you will read why the scientists conducting them rejected Vom Saal et al's evidence. Methodology, statistical power, low sample size - there isn't a debate, there's a wipe out. Read the reports and tell me I'm getting it wrong, that I'm missing something...

The idea that BPA is controversial has been created by the media and environmentalists and a small group of scientists. All have good reasons to do so. But that doesn't make what they say true.

10:12 AM, July 11, 2008  
Blogger Nick Barrowman said...

One of the main conclusions of the NTP draft brief on BPA is:

The National Toxicology Program (NTP) concurs with the conclusion of the Center for the Evaluation of Risks to Human Reproduction (CERHR) Expert Panel on Bisphenol A that there is some concern for neural and behavioral effects in fetuses, infants, and children at current human exposures. The NTP also has some concern for bisphenol A exposure in these populations based on effects in the prostate gland, mammary gland, and an earlier age for puberty in females.

These experts are not convinced that BPA is harmless.

9:28 AM, July 19, 2008  

Post a Comment

<< Home