Tuesday, May 24, 2011

The Tuesday Toxin Talk

I'm currently reading Slow Death by Rubber Duck, by Rick Smith (Executive Director of Environmental Defence) and Bruce Lourie (President of the Ivey Foundation). The book examines the toxins that leach out of commonplace items in our homes and workplaces and wind up in our bodies. Smith and Lourie experiment on themselves, purposely exposing themselves to everyday products over a four-day period, and use the results to raise awareness about the dangers that surround us. I'd like to use this space every few Tuesdays to share some of this vital information with you. For more in-depth coverage, please buy the book!


Let's talk about mercury.

Humans have been using mercury for a very long time: the ancient Romans recovered gold and silver by mining with mercury; medieval monks transcribed religious documents with mercury-based inks (and subsequently died of mercury poisoning); Renaissance physicians used the toxin as a cure-all for everything from skin lesions to constipation; and we all know about the mad hatters that breathed in mercury fumes while creating beaver felt hats. These days we don't concern ourselves so much with coming into direct contact with the metal, but our long-term exposure to tiny amounts of mercury in our food is causing neurodevelopmental problems, especially in children. To give you an idea of how nasty this stuff is, exposure to high levels of mercury can cause permanent brain damage, central nervous system disorders, memory loss, heart disease, kidney failure, liver damage, cancer, loss of vision, loss of sensation, and tremors. It is also an endocrine disruptor, damaging the reproductive and hormonal development of fetuses and infants, and may even be linked to multiple sclerosis, attention deficit disorder, and Parkinson's. In other words, mercury will kill you if you breathe it, eat it, or expose yourself to high enough levels - and no level of mercury is safe, ever. Just one gram can contaminate the fish in a 20-acre lake.

Where is all of this mercury coming from, anyway? Apparently a lot of it contaminates our water and fish because we humans use and dispose of everyday consumer products. In other words, we're exposing ourselves to it twice: once from the products we use, and again from the fish we eat that live in the water we pollute. That's not a comforting thought. Naturally-occurring mercury is infrequently released in small amounts by volcanoes, forest fires, and oceans. On the other hand, human-generated mercury is everywhere, all the time: waste incinerators, coal-fired power plants, and everyone's favourite energy-efficient fluorescent lights all contribute to the excessive amounts of mercury in the environment. You can find mercury in your house if you still have old-school silent light switches (the ones that don't click on or off but rather give no resistance or noise when flicked), tilt switches that turn the light on in your chest freezer and the trunk of your car, those classic round thermostats, and old paint. Luckily none of these are sold in Canada anymore, but shockingly, we still put mercury in children's vaccines.

The easiest way to avoid exposure to mercury is to watch what you're eating - and it's widely known that some tuna carry high levels of mercury. Among the many varieties of canned tuna, solid white tuna has the highest levels of mercury. A safer option is flaked or chunk light tuna, which has a lower amount of mercury because the fish used in flaked tuna tend to be smaller, so the effects of biomagnification don't play a big role. If you're unfamiliar with the term, biomagnification refers to higher levels of toxins ending up in larger predators near the top of the food chain because they accumulate the toxins their prey have eaten. Small fish are also safer for us to eat because they are younger and haven't had as much time to bioaccumulate mercury in their diet over decades, unlike the giants that are the most prized for sushi.

So the steps are clear: choose flaked or chunk light tuna in cans (let's ignore the BPA in the cans until we get to chapter 8!) and avoid tuna when you go out for sushi. There are great online resources when it comes to eating fish and staying healthy. I carry around a pocket guide from Toronto Public Health that explains how often you can eat different types of fish depending on which risk category you fall into. What I love about this guide is that it also highlights which fish are high in omega-3s, and which are farmed/caught in ways that harm the environment. The only drawback is that it was created for Toronto residents: in other parts of the country and abroad, the same types of fish come from different places.

But don't stop there! Make sure you're properly disposing of fluorescent lights, batteries, electronics (and if you renovate, drywall with mercury paint) at a hazardous waste depot. Let's not allow any of these products to end up in a waste incinerator! And as always, reduce your electricity use to lower how much mercury is released into the atmosphere from coal-burning power plants. Most importantly: tell this to everyone you know!

Have I covered it all? Do you know of any other sources of mercury that we should avoid?

Photo credits: mercury droplets; mercury thermometer; tuna market.


  1. Great post Andrea. I'd like to suggest one correction though. The mercury found in vaccines is in the form of thimerosal. It is used as a preservative and there is no evidence it causes health issues. As a precaution, it has been removed from vaccines that don't require it and diminished in vaccines that do. (http://www.who.int/vaccine_safety/topics/thiomersal/statement_jul2006/en/)

  2. Thanks Eric, that's a relief. I wish the authors had included that piece of information in this chapter of the book!

  3. I've been hesitant about making a complete switch to CFLs because of the mercury. I had a box of incandescents to use up and figured I'd make the switch after that. I still haven't finished using them up and might as well wait for LED lighting to become more affordable!

  4. I can't blame you. One of my biggest beefs with CFLs - second to their mercury content, of course - is that we're throwing away incandescent bulbs before they've been fully used. Why not keep them until they die, and use them less to conserve? Creating trash as a side effect of saving electricity doesn't make a lot of sense to me.

  5. I've held out on switching to CFLs exactly because of the mercury reason. It's not an easy decision to make though; if your home's energy comes from a coal-burning power plant (like mine), then any electric usage contributes to mercury contamination of the environment. Unless we switch to reading by candlelight, it's just best to reduce light usage.

    I'd be interested in a Toxin Talk about BPA contamination in canned foods. I've read that tomatoes and coconut milk contain the most BPA of any canned food due to their high acidity. This is disturbing because these are really the only two foods I eat from cans (and beans). I hope to can (in jars) and freeze a bunch of farm-fresh tomatoes this summer to avoid the canned stuff.

  6. Thanks for the comment, Emily. There will definitely be a TTT about BPA. I'm equally disturbed that canned tomatoes contain the most BPA! I will be attending a canning and preserving workshop in June but am concerned that I won't can enough tomatoes to last me a whole year. Still, even a little is better than nothing.