During the 1960s and 1970s, the world was shocked by the horrors of mercury poisoning in Japan and other places, leading to a reduction in mercury pollution from human activities such as coal burning and mining. However, a recent study by French researchers analyzing tuna samples from 1971 to 2022 found that mercury levels in the fish have remained unchanged. This is likely due to “legacy” mercury moving from deep ocean layers to shallower depths where tuna feed.
The researchers predict that even with strict regulations, it could take another 10 to 25 years for mercury concentrations in the ocean to start decreasing, with a further delay before mercury levels in tuna begin to drop.
This highlights that the fight against mercury pollution is ongoing. David Point, an environmental chemist and study author, emphasizes the need to significantly reduce emissions to see any progress in the coming decades. Mercury, primarily emitted through human activities like mining and burning fossil fuels, ends up in the oceans where it accumulates in fish and shellfish.
Mercury exposure from contaminated seafood can have harmful effects on human health, especially for unborn children. The slow healing process of the earth is evident in the persistence of mercury in tuna, despite global efforts to reduce emissions.
The study, which analyzed nearly 3,000 tuna samples from different oceans over several decades, found that mercury levels in tuna have not decreased as expected. The complexities of ocean mixing and the impact of climate change on mercury circulation raise concerns about future pollution levels.
Although no single sample of tuna exceeded health standards, the cumulative effects of mercury exposure underscore the need for stronger restrictions on its use, including in industries like gold mining. Without further action, contaminated tuna could persist well into the next century.
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