By: Amanda Giang
When I’m not in glamorous Geneva, and instead in my much-less-glamorous cubicle in Cambridge, MA, I work on assessing the benefits of reducing mercury emissions. The bulk of these benefits are related to improved health—reviewed in our earlier post. Discussion on the health impacts of mercury normally focus on neurologic effects—and with good reason. These effects often have devastating impacts on the lives of victims, and heavy social and economic costs—even when we’re talking about subtle IQ loss from fetal exposure to methylmercury.
What’s more, we have a large body of scientific evidence that helps us understand these neurologic effects, and that can help guide policy decisions about preventing them. But, focusing on just neurologic effects may not tell the whole story. There may be other—though considerably more uncertain—health effects from mercury exposure that have serious policy implications. A large part of my research is about how to include these uncertain health effects in estimating benefits from reduced mercury emissions.
Of these uncertain effects, cardiovascular impacts may be the most important, and also the least uncertain. A growing body of evidence suggests that there may be a causal relationship between methylmercury and cardiovascular disease (coronary heart disease, heart attacks, increased blood pressure). Scientists still aren’t sure why mercury might promote heart attacks; one hypothesis is that it causes oxidative damage.
A committee convened by the US EPA recently decided that there was enough evidence, at least for heart attacks, to warrant including this health effect in future benefit assessments for mercury regulation.* Taking into account mercury-related heart attacks is important because the “cost” of a heart attack—personal, social, and economic—is very high; particularly if a heart attack leads to a fatality. In one of the first studies to include heart attacks in its calculations of costs and benefits, 80% of the benefits associated with reduced mercury exposure ($8.6 billion/year in the US) were due to reduced heart attacks.
If, through further research, it turns out there is a causal relationship between mercury and heart disease, then this week’s mercury treaty might be even more socially beneficial than countries initially thought. This was the case when the US regulated sulfur dioxide in the 1990s. Originally, the focus during the policy’s development was on environmental benefits from reduced acid rain. However, it later emerged that reducing sulfur dioxide has huge health benefits (an unexpected $70 billion/year!). As the science develops, we’ll see whether this will play out for mercury as well.
* NOTE: In the US, part of the regulation making process involves assessing the costs and benefits of regulation.