Mercury Accumulation in Humans and Ecosystems Envirotech Online

Even in 2013, when it was officially ratified, the UN Minamata Convention on Mercury had a desperate sense of urgency, having already run out of time. As one of the most harmful anthropogenic pollutants, coordinated reduction of exposure and emissions immediately rose to the top of the priority list in public health management around the world. More recently, however, this emergency has become part of another global race against time, as concerns have begun to be raised about mercury’s role in the climate crisis. As a contribution to these discussions, this year’s International Conference on Mercury as a Global Pollutant (ICMGP), which started today, will focus on innovations to reduce mercury emissions to achieve a greener world.

Our understanding of mercury is still developing. Like any other evolving field, mainstream knowledge lags behind research. Take a common sentiment regarding mercury levels in fish: “It’s better to eat a good amount of fish because it’s so healthy, but it’s better to limit yourself because of all that mercury.” Now consider the state of scientific research: for years, observational epidemiological studies have confirmed that eating fish during pregnancy benefits the neurological development of children, studies that researchers concerned about methylmercury toxicity have criticized for focusing on populations with some of the lowest rates. fish consumption rate.

To address this omission and begin to clarify the true link between fish consumption, maternal nutrition and adverse effects, Dr. Alison Yeates of the University of Ulster conducted an experiment in a population relatively exposed to methylmercury. Surprising conclusion of Dr. Yeates? Where fish consumption is significantly higher than current global recommendations, no evidence was found of negative associations between maternal fish consumption and children’s neurological development at many time points up to age nine. . A victory for the pescatarians, then?

Well, it might be better to hold your horses (or some salmon, maybe?). Speaking on behalf of the Instituto de Salud Carlos III, Ana Cañas Portilla, Ph.D., paints a darker picture. Although human biomonitoring studies of mercury exposure from seafood have been all the rage for a few years now, none have yet focused on teenagers. Last year, the first national survey of mercury levels in adolescents was conducted in Spain. About 500 teenagers (aged 14-16) were sampled, all living in cities, using atomic absorption spectroscopy. As expected, teenagers from two coastal cities, Huelva and Alicante, showed the highest mercury levels. Even more disturbing, about 13% of participants had mercury levels in their hair that exceeded the World Health Organization recommendation (2.3 μg/g). So it’s safe to say that the ICMGP 2022 gave attendees plenty of food for thought on the issue of fish consumption.

From the deep blue sea to the deep blue ice cores of the Arctic and Antarctica, now, as Saebom Jung of Pohang University of Science and Technology tells us about research on internal mercury dynamics in penguins , which could serve as a potential bioindicator of mercury in the most remote regions of the Earth. As Ms. Jung notes, this is an under-explored topic, as most researchers prefer to study more typical terrestrial and freshwater environments. Much of the mercury that enters the poor Adelie and Emperor penguins studied by Ms Jung’s team comes from rivers in the High Arctic that have been badly affected by permafrost degradation, on which Jane Kirk of Environment and Climate Change Canada provides a fascinating (and disturbing) talk. After studying changes in mercury fluxes over a decade, Ms. Kirk is confident in predicting that the transport of mercury along these High Arctic pathways will only increase as climate change forces the rains to migrate to these areas and cause local temperatures to rise, degrading and disturbing nearby permafrost.

With this heady and unsettling conclusion, it’s probably best to put our feet on the ground. For the University of Colorado at Boulder, Hannah Miller presents us with a paradox. Although the United States has been successful in reducing its mercury emissions in recent years, many mountain biospheres in its westernmost regions are receiving increasing rates of mercury sequestration. Unfortunately for the United States, Miller notes, mountain systems have been reported to be some of the most efficient mercury sinks – for example, Miller cites a study that holds these ecosystems responsible for absorbing up to 80% of atmospheric mercury!

It is an open question, however, as to why this might be the case; Miller’s presentation highlights readings that suggest this sequestration has more to do with the type of soil found at that altitude than the elevation itself. But mountains are of course not the only terrestrial ecosystem with a penchant for absorbing mercury, as David McLagan, Ph.D., of Queens University reminds us. Primarily, trees take up mercury from the atmosphere via stomatal assimilation of gaseous elemental mercury, where it is oxidized and transported to parts of the anatomy that retain it for long periods of time. Indeed, Mr. McLagan observed this long-term contamination during the fractionation of sapwood and xylem solutions.

It was another whirlwind day, with over twenty unique and thought-provoking presentations from some of the world’s leading researchers, regulators and inventors working in the field of mercury pollution. Perhaps the best part, however, is that we still have four days ahead of us. It must be said, and said again, that if you are involved in environmental mercury, there really is no other place you should be than at ICMGP 2022.

For more information, visit the International Conference on Mercury as a Global Pollutant.