The future cost of mercury exposure

Featured image: Rice paddy fields in Indonesia by Steve Douglas on Unsplash

Paper: Zhang, Y., Song, Z., Huang, S. et al. Global health effects of future atmospheric mercury emissions. Nat Commun 12, 3035 (2021).

Methylmercury, the organic form of the element mercury, is everywhere. A common global pollutant, this form of mercury is most commonly consumed by humans in food, and subsequent impacts include heart failure and loss of IQ. Environmental mercury is nothing short of a public health crisis, and while global interventions are rolling out to protect humans from this toxic pollutant, new research published in Nature Communications is showing us that the damage isn’t just in human lives, it’s also in dollars and cents. 

Through their model projections, Yanxu Zhang and colleagues found that the impacts of mercury exposure across the next 30 years include a loss of $117 billion, 0.086 IQ points per newborn fetus, and over 29,000 annual deaths (defined as fatal heart attacks caused by mercury exposure). To calculate these figures, the researchers relied on a three-dimensional atmosphere/ocean model and a two-dimensional land model to study the distribution of mercury through the environment.

The main pathway for mercury to enter the human population is through food consumption, and coastal countries with a high rate of seafood consumption are the most susceptible due to mercury’s increased presence in the ocean. Zhang and the team found that the countries consuming the most mercury per person per day are the Maldives (33 micrograms), Greenland (16 micrograms), Iceland (15 micrograms), and Kiribati (13 micrograms). 

Similar trends appear in those countries that consume a high amount of rice—a crop highly influenced by soil contaminants, like mercury. Southeast Asian countries like Indonesia, Laos, and Cambodia, were the highest consumers of mercury per day, with 1.7, 0.90, and 0.77 micrograms per day, respectively.

Health and economic impacts of mercury exposure under present-day estimates. Top row: decrease in IQ per fetus and deaths from fatal heart attacks. Bottom row: economic loss from reduced population IQ and heart attack deaths. Figure reproduced from Zhang et al. (2021) under CC-BY 4.0.

In order to determine the monetary impact of mercury exposure, Zhang and colleagues related monetary value to change in IQ and deaths from fatal heart attacks. More specifically, one IQ point corresponded to $18,832 in this study. Similarly, the team used a “value of statistical life” to estimate economic loss per death. A 2017 report by the think tank Strata states that the value of statistical life “measures what an individual is willing to pay to reduce a certain risk level.” The researchers used a value of statistical life per death of $6.3 million dollars following previous work on this topic.

Based on these assumptions and calculations, Zhang and co-workers found that the United States will lose $21 billion per year based on IQ reduction of newborns of fatal heart attacks, followed by China ($15 billion), Russia ($12 billion), and Japan ($9.3 billion).

These numbers are staggering, but there is potential to minimize these outcomes. Currently, global mercury emissions total over 2,220 metric tons per year as of 2018. In a “business-as-usual” projection, this figure will increase to 4,900 metric tons per year. But in a scenario including emission reduction, this number may drop to 1,020 metric tons per year. While these figures are not ideal, they prove that there is an opportunity to reduce global emission of mercury into the environment, subsequently reducing the financial and anthropogenic toll therein.

The future cost of mercury exposure by Kevin Hurler is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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