Toxic Elements from “Chemistry and Sustainability”

This morning, I taught my advisor’s undergrad/grad class on sustainability. They’re currently studying “toxic elements,” so I introduced the lesson and showed a few videos on lead, arsenic, and selenium poisoning. In the last 15 minutes I discussed with the students if the class is impacting their daily lives and why it should, which of course reminded me of why I blog. 

I’ve linked to the videos we watched today in class. We learned first about lead poisoning in children in Nigeria due to contaminated dust from illegal gold mines. Human Rights Watch named it one of the worst lead poisoning epidemics in modern history. Bangladesh is also experiencing “the largest mass poisoning of a population in history” from naturally-occurring arsenic in groundwater. 

These are extreme and geographically and socioeconomically distant examples, but lead and arsenic poisoning can and do occur to us, too. Lead, which I’ve written about before, was used heavily in paint and gasoline until it was banned in the 1970s and 80s, respectively. Lead is a persistent toxic pollutant and continues to contaminate soil and our homes. Most homes built before the lead paint ban (including mine) still have leaded paint underneath the top layers, which poses a threat to children who may eat the paint chips and to anybody who breathes lead dust. Lead use in paint and gasoline has also been epidemiologically correlated to a decrease in IQ and increase in violence in the 20th century. Low dose exposure of children to lead manifests itself in lowered IQ scores.

There are two main sources of arsenic poisoning that you should worry about as well: groundwater contamination and rice. Arsenic deposits in soil are naturally occurring (see below for major pockets), and can contaminate well water. Researchers recently measured the (low) levels of arsenic in well water in Maine and correlated it to a decrease in IQ in children. Takeaway: if you drink from a well, always have it tested for heavy metal contamination. 

Arsenic poisoning can also occur through rice consumption. The rice plant absorbs arsenic and other heavy metals including cadmium, mercury, and tungsten and stores them in the grain. For cultures who eat rice most frequently, this has lead to diseases such as the painful “ouch-ouch” in Japan. Brown rice contains more arsenic than white rice because it accumulates in the bran, but is less healthy. The highest levels of arsenic have been found in rice grown in the southern United States; imported rice from Asia is mixed in arsenic levels. See Consumer Reports full rice test results hereConsumer Reports and the EWG recommend buying rice from California and limiting rice consumption for babies. Those on a gluten-free diet should also be mindful of rice intake. 

Scary, yes, but manageable. If you made it this far and are feeling pretty down, watch this funny John Stewart video on selenium that I am not skilled enough to figure out how to embed.

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