Anti-vaxxers can’t do math

October 25, 2011

A posting at a “newspaper” (I use the term loosely here) called the Canadian entitled ” America’s Toxic Flu shots: 250 times EPA mercury limit” has been getting a bit of attention (and ridicule) lately. The same article appears to be posted at another site under the name “Flu Shots Contain More than 250 Times the EPA’s Safety Limit for Mercury“, both by someone called¬†Anthony Gucciardi. The article is riddled with factual errors, and actually identifies well-known quack Russel Blaylock as a “leading neurologist”. But without even going into all the factual errors, which have been pointed out elsewhere (such as here), the article has fundamental math errors that¬† make it even more laughable.

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Mercury exposure from compact fluorescent lights

September 27, 2011

A commenter on a previous post asked about potential mercury exposure from broken compact fluorescent lights (CFLs). There are also various stories floating around the internet (such as this one) about the dangers of mercury in CFLs. So I thought I’d take the opportunity to look at how much mercury someone could be exposed to from a broken CFL, and whether there were any risks from that level of exposure.

A CFL typically contains about 4 mg of mercury (according to US EPA); a lot of newer CFLs contain 1 mg or less. I’ll look at the worst-case exposure, so let’s go with 4 mg of mercury in a bulb. In reality that mercury isn’t going to all be in the air right away – the evaporation rate of mercury is about 56 micrograms per hour per square centimetre – but figuring out the rate at which it enters the air requires assumptions about the area covered by the spilled mercury, temperature, pressure, etc. To keep things simple and to make sure I’m considering the absolute worst case, I’ll assume that all of that mercury instantly volatilizes.

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Classification of formaldehyde as a human carcinogen

June 20, 2011

There have been a few reports in the news recently about how the US government has added formaldehyde to their list of substances known to cause cancer in humans. This doesn’t really come as a surprise – the International Agency for Research on Cancer (IARC), for example, already classifies formaldehyde as a confirmed human carcinogen. But since there’s some media attention on the subject right now, and since formaldehyde exposure can occur from a variety of sources, including many consumer products, it seems a good time to look at what this classification means for the general public.

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Methylmercury and fish consumption

June 9, 2011

After a bit of a break, I’m getting back to my series of posts related to mercury. This time I’ll focus on methylmercury, which is generally considered to be one of the “nastier” forms, since it is relatively toxic (primarily neurotoxicity, but also believed to cause cardiovascular and reproductive toxicity at high doses) and also bioaccumulates in animals. Since the main source of methylmercury exposure is food, and in particular fish, I’ll look at how the amount of mercury in fish relates to potential effects on humans.

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How toxic is BPA?

April 27, 2011

ResearchBlogging.org
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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Phthalates in children’s toys

January 18, 2011

The Government of Canada has just announced new legislation that will significantly restrict the levels of six phthalates in children’s toys and child care products. Europe imposed similar restrictions several years ago, and the US in 2009. Today I’ll briefly look at why these restrictions are in place, why they only apply to toys and child care products, and what it all means.

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San Antonio Statement on Brominated and Chlorinated Flame Retardants

November 24, 2010

ResearchBlogging.org

A group of nearly 150 scientists has signed a statement about brominated and chlorinated flame retardants (BFRs and CFRs), essentially asking for some serious thought to be given about whether we really need to be using them the way we are.

BFRs and CFRs have been used in a wide range of products due to their fire retardant properties, including furniture, carpets, automobiles, electrical equipment, insulation, adhesives, appliances, construction materials, paints, and more. Unfortunately they are also highly persistent in the environment, and several of them have been found to be highly toxic. Several of these compounds have been banned; however, these have generally been replaced with other BFRs and CFRs.

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