On February 4, 2013, Dr. Charles Wong (environmental studies and chemistry, U of W) and Dr. Feiyue Wang (chemistry, U of M), explained how toxic organic chemicals and trace metal contaminants find their way to northern communities, how they affect human health and ecosystems, and potential solutions to these problems.
Wong began by explaining that the Arctic has relatively high concentrations of many persistent organic pollutants, or POPs. These are manmade chemicals that can last decades or millennia and are toxic to environments and humans. Many POPs cause cancer and abnormalities. They are also bio-accumulative, meaning that higher levels of these chemicals are found at higher levels of the food web.
“Folks, we’re at the top of the food web – that ain’t so good,” Wong said.
POPs such as DDT, polychlorinated biphenyls (PCBs), and perfluorinated compounds in products like stain repellants are mainly used in warmer and more populated regions of the world. In fact, POPs are hardly used in the Arctic. So why does the Arctic have such high levels of POPs? Part of the reason is that many of these chemicals are volatile or semi-volatile, meaning they can easily turn to a gas.
“Once [a POP] goes into the air, then it can go whenever it wants,” Wong said. “So if it goes up in the air and it’s warm, it can move up … to further latitudes where it’s colder. And if it’s colder, it can then sink back into the [ground or water].”
This process is called atmospheric transformation, which Wang noted is also partially responsible for the Arctic’s high concentrations of toxic trace metals such as mercury and lead. Though current levels of these contaminants are alarming, Wong and Wang agree that there are some solutions.
“[We can] deal with the new chemicals that are coming out here and try to make some insights so we don’t make the same mistakes that we [did] before,” Wong said. “You may not want to eat certain types of native foods or limit your consumption to minimize the risk of being exposed.”
Wang noted that pieces of international legislation, such as the Kyoto Protocol and the Stockholm Convention, are steps in the right direction.
“Right now, we’re in the midst of finalizing a globally and legally binding instrument for mercury emission control, which Canada will be signing, I hope,” he said. “I do think that with science and law, things will eventually be helped.”
Questions asked this week:
On one of your slides, you showed that the DDT levels in Lake Michigan are coming down. What’s happening in the Arctic? Has there been any change?
Wong said it depends on which chemicals you look at. “For the legacy chemicals, yes, they went down quickly after worldwide bans were put into effect. These days, things have pretty much leveled off… But for emerging chemicals, concentrations are going up.”
Are there any recent studies on these chemicals in the breast milk of women living in northern communities?
Wong said breast milk studies offer valuable insights into the changing levels of POPs. “We can see some of the older chemicals … go down, but some of the newer replacements actually go up,” he explained. “It does seem that human tissue and material sets up a steady state, so that what goes in tends to balance what goes out and controls the actual concentration that’s in you.”