How toxic is BPA?

April 27, 2011
The toxicity of bisphenol A (BPA) has been a fairly controversial subject for a while. Industry groups have been fairly adamant about its safety, while many environmental groups suggest it is causing adverse health effects in humans. Messages from regulatory agencies have been fairly mixed, or even confusing. While Canada declared the substance “toxic” under the Canadian Environmental Protection Act, they did not actually conclude that it was causing a risk to human health. The US National Toxicology Program found “some concern” for infants and young children, based on insufficient data in humans and limited evidence of developmental effects in animals. The World Health Organization concluded that further regulation was not warranted based on current information, but that there were data gaps where further research is needed.

A couple of years ago, a paper was published by Myers et al. (2009) (a paper with 36!!! authors from 30 different institutions) that was highly critical of the methods used by public health agencies for the evaluation of BPA toxicity, and in particular their reliance on studies conducted using “Good Laboratory Practice” (GLP) standards over academic studies. Now a new critical review has been published by the Advisory Committee of the German Society of Toxicology (Hengslter et al., 2011) that concludes the European tolerable daily intake (or “safe dose”) of 0.05 mg/kg body weight/day is justified (for comparison, the US also uses 0.05 mg/kg/d, while Canada uses 0.025 mg/kg/d). This review also takes specific aim at the Myers et al. paper and rejects its conclusions.

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Canadian 2011 Federal Election – where do the parties stand on science-related issues?

April 21, 2011

For a bit of a change of pace from my usual content, today I’m taking a brief look at the major Canadian political parties and the parts of their platforms relating to science and science education. Obviously there’s a lot more to consider before voting than this, but there are plenty of other sources for that information. I’m going to stick to what is actually in the published platforms for the most part. Of course, past history shows us there is also no guarantee any of the parties will actually follow through on what is in their platforms.

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Does aspartame cause cancer?

April 15, 2011

This post was chosen as an Editor's Selection for
Aspartame and other artificial sweeteners have long been a source of controversy and debate regarding whether or not it has adverse health effects. Among the effects claimed, perhaps the most serious is potential carcinogenicity. However, industry and regulators generally maintain there is no evidence of carcinogenicity. Is the risk real?

To answer this question, I’ll look at two papers. On the “yes” side, the primary evidence of carcinogenicity comes from a bioassay conducted by the Ramazzini Foundation (Soffritti et al., 2007), which concluded that aspartame caused multiple forms of cancer in experimental animals at doses close to the human acceptable daily intake, with increased effects when exposure begins early in life. However, several agencies and researchers have been critical of the methodology and interpretation in this paper. I also did a quick independent look at several other carcinogenicity studies conducted by the Ramazzini Foundation, and every study I looked at had a positive result, which raises a bit of a flag.

On the “no” side, I’ll look at a safety evaluation published by Magnuson et al. (2007). This evaluation looked at animal bioassays (including the Ramazzini Foundation study) and human epidemiological data, and concluded that the data indicate aspartame is safe and that the Soffritti et al. 2007 study does not provide convincing evidence of aspartame carcinogenicity. However, this study was sponsored by Ajinomoto Company, Inc., the major producer of aspartame, and as a result the potential for bias has been raised. I do not believe that a study should be automatically discredited just because it was sponsored by a company with a financial stake in the outcome, but it does mean the conclusions should be examined carefully in case of any bias, whether intentional or not.

When there are two studies with conflicting positions, both of which of questions about their quality and/or potential biases, then instead of relying on the conclusions of the authors we need to look closer at the actual data.

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One year of exposure/effect

April 1, 2011

Well, I’ve made it through a full year with this blog; not bad since I’ve heard the average blog only lasts 3 months. A big “thank you” to all my readers, regular and casual – if no one was reading then it wouldn’t be worth my time to keep this up. To mark the anniversary I’ve added a new page, “Best of exposure/effect”, with links to some of what I think are the best posts here, mostly for the benefit of new readers.

I’ll indulge myself in a brief review of what I’ve accomplished this year, and what my hopes/plans for the future of this blog are:

The 2011 “Pigasus” Awards

April 1, 2011

The James Randi Educational Foundation has announced this year’s winners of their “Pigasus Awards” for “the most deserving charlatans, swindlers, psychics, pseudo-scientists, and faith healers.” Their winners are excellent choices:

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