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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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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The many faces of mercury

March 24, 2011

This is the third in a series of posts about mercury (see also Part 1 on measuring mercury exposure and Part 2 on sources of mercury exposure).

It’s easy to think of mercury as a single substance. However, there are several different forms of mercury, which exhibit very different behaviour in the environment and in the human body. Today I’m going to briefly introduce some of the different mercury compounds, where they come from and what happens to them; future posts in this series will focus on the effects of some of the key mercury compounds.

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Causes of high mercury levels

March 2, 2011

ResearchBlogging.orgThis is the second in a planned series of posts relating to mercury exposure and toxicity (see also Part 1: measuring mercury exposure and Part 3: the many faces of mercury). In this part I’m going to look at some of the causes of high mercury levels measured in the population, and specifically at a recent population biomonitoring study conducted in New York (McKelvey et al., 2011) where follow-up interviews were conducted with people who had abnormally high levels of inorganic mercury in urine samples (the mercury in urine is almost totally inorganic). The methodology was based on the methods used by the CDC for the National Health and Nutrition Examination Survey (NHANES), and included 1,840 people across a variety of social strata, ethnicities, races, and education levels.

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Measuring mercury exposure (and why provoked urine testing is the wrong way to do it)

February 18, 2011

A commenter by the name of “Robin” asked for information on mercury toxicity a while back due to her husband having reported high mercury levels. My workload is finally getting close enough to being under control that I can tackle this. However, it’s a complicated topic with a few different aspects. Before I actually get into some of the effects of mercury, I think a bit of context is important. So for this first post I’m going to talk about how mercury exposure is measured and how to know if mercury levels really are elevated. I’ll follow that up with some future posts (hopefully within the next week or so) about where this mercury exposure is coming from, and what the effects can be [Update: part 2 on some causes of high mercury levels is here, and part 3 on the different types of mercury is here]. Some of the concepts in this post build on an earlier entry on measuring chemicals in blood and urine.

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