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What is it about mercury? Thinking about chemicals in the public discourse

All of the revelations about the lead in the water system of Flint, Michigan have made residents and curious neighbors alike  wonder ‘haven’t we solved the lead problem’? There are thousands of well-established scientific studies; the sources and even many of the solutions are well-understood and frequently implemented. Not to say the problem’s gone, but we’ve wrapped are heads around it. So how is it possible that a new lead problem has surprisingly reared its ugly head? And more importantly, what does that mean for exposure to chemicals for which we’ve barely scratched the scientific surface?

The world of fisheries has its analog – mercury. We’ve all heard the recommendations for pregnant women and small children to avoid tilefish, swordfish, mackerel, and shark. We understand that it bioaccumulates in the food chain – and that as humans not exactly at the bottom, we’re susceptible. The dynamics of methylmercury (the poison variety) and elemental mercury are fairly well mapped out and we can identify areas of potential hazard where more methylmercury is likely to be naturally created. We’ve also stopped doing things like spraying mercury-based pesticides and covering our landscape and foodscape with the toxin. Kids have even stopped playing with ‘quicksilver’, it’s been removed from dental fillings and vaccines, and you should get rid of that mercury-based thermometer. Yet, if you scanned most people’s hair (the way we measure these things), there would be mercury present. And there’s still a host of ways they might have been exposed. But the better question is – if there’s still mercury in your body, what else is floating around in your system? And why do we focus on only the best-understood pathway of chemical exposure?

Modern Mercury Exposures

If you ask people what water quality concerns we should pay attention to in coastal, small-scale fishing communities and they’ll say mercury first (such a question produced this research). These fishermen get questions from their consumers occasionally and health-conscious consumers becoming more prevalent. It’s the only public health concern that the big fish guides, like the Monterrey Bay Aquarium cards,  test for. Ask those same people how they think the mercury got there and why they think it’s a concern, and they’ll list local or regional phenomena like historic land use (those pesky mercury pesticides again), presence of Superfund sites, and urban industrial discharges.

What they won’t say, but what the scientists will tell you, is that the majority of mercury these days comes from coal-fired power plants. They’re engineered these days in the US with “best available control technology” and many other nations share the same technology. However, that technology is often just a taller smokestack to deposit said mercury further up in the atmosphere. So instead of falling on the houses in the neighboring community like it used to, the mercury gets a jump start for global distribution in the high winds of the upper atmosphere. That means if you’re living on the east coast of the US, you’re mercury exposure is most likely coming from Chinese power plants. The mercury from turning your lights on is visiting your European friends.

Plus, mercury still has industrial applications. Do you have compact fluorescent lightbulbs in your house in order to cut down on carbon emissions? Those contain mercury. Waste management companies have special handling procedures to deal with old or broken CFLs, but it’s a fair guess to say that most end up in the regular trash along with 75% of other recyclables (in some areas). In a quest to help with one enormous environmental problem, we are contributing to another.

Have a gold wedding band? Yet again, the mercury villain rears its ugly head. Small-scale gold extraction across the developing world still depends on mercury to extract the gold from the surrounding rocks. This means that the workers frequently report mercury poisoning and the rivers from which this gold is mined flows downstream to communities, houses, and schools full of the mercury used to extract gold. Every once in awhile, a community particularly hard-hit will be profiled by international media, but otherwise the story is a fairly quiet one.

These points are all a way of saying that despite the fact that people care about mercury, think about it regularly, and place it at the top of a long list of environmental concerns, there are still aspects of the mercury problem that fly below their radar. So if we’ve got a public consciousness about mercury, how do we focus it to the most current concerns in a way people can take action? What is it about mercury that keeps it in people’s public consciousness and what can we learn to help both the mercury problem and other environmental concerns moving forward?

Why can’t we think about chemical exposure more broadly?

Despite lingering problems with mercury, it represents one of few chemical or water quality problems that we can, to a certain degree, place in the “success” box. There are laws in almost every country regulating its use (enforcement continues to be a problem, but that’s a story for another time) as well as broad public health campaigns about current exposures through thermometers, seafood, and industrial effluents. Parents and grandparents today tell stories of playing with quicksilver in school but how they’re glad that science has told their future generations that despite the fun of liquid metal, it’s not a safe activity. Yet, it’s still a public health concern via new pathways of exposure that get far less attention and that tend to be out of the public discourse.

Furthermore, the mercury story makes one wonder what else is out there that we as a scientific community have not yet had the time or funding to fully investigate. There are approximately 60,000 synthetic chemicals registered and used industrially that can be added to the list of naturally occurring compounds with public health implications (like mercury). In the US, these are not routinely tested before application in wide commercial use. Plasticizers like bisphenol-a are a good example – once widespread in almost every form of plastic object (which are fairly ubiquitous), we now understand they act like the body’s natural estrogen and cause developmental and hormonal problems. Plastic producers have responded by swapping it out for new plasticizers, none of which have gone through a thorough review to see if they have similar problems.

Take even one of mercury’s main routes of exposure – application to the land through pesticides – and while mercury’s now out of the pesticide arsenal, we spray plenty of very potent chemicals on our fields to this day. The route of exposure remains and concerns over farmworker and farm community safety occasionally bubble to the surface. The rise of organic produce options show that some people care, but even organic farms are allowed to use some untested chemicals to keep the bugs away. Since the beginning of toxics regulation in the US, only 4 chemicals have been banned from use and the Toxic Substances Control Act (the main regulation on chemical use) only tests or monitors about 10,000 chemicals. It’s a long, steep road to controlling our exposure to unhealthy chemicals, let alone those with primarily environmental effects. How do we get people to talk about these types of chemicals in the same way that they talk about mercury? After all, it’s getting to them in the same sorts of ways.

Fundamentally, what can we learn from mercury’s story? What placed it high on the list of people’s concerns and what keeps it there? Why haven’t other chemicals joined mercury as literal poster children for environmental health? Let’s use mercury as a window into how the public interprets and reacts to scientific information and move our understanding of chemicals forward with broader support from the public.