The study tested 39 sea salt brands from 21 countries over six different continents, 36 of the 39 salts contained microplastics. The findings, published in the journal of Environmental Science & Technology, found that only three salt brands were free of microplastics, a refined sea salt from Taiwan, a refined rock salt from China and unrefined sea salt produced by using solar evaporation in France
What are microplastics?
Microplastics, the result of the degradation of larger plastic products, are small pieces of plastic that measure less than 5mm. They are found throughout the world in rivers, oceans and soil and the study showed a correlation between places with higher plastic emissions and those with more plastic in their salt. Seung-Kyu Kim, Incheon Nation University, said: “The finding suggest that human ingestion of microplastics via marine products is strongly related to emission in a given region.”
Asia was shown to have the highest levels of contamination, with Indonesia showing the highest mass of microplastics across the study. These findings echoed in a separate study on microplastic by the Jambeck Research Group back in 2015. However, the plastic traces were found in salt from across five continents. Sea salt was found to contain the highest levels, followed by lake salt and rock salt.
How harmful is this?
The journal publication suggests that the average human consumes approximately 2,000 pieces of microplastic every year through salt, but there is little data available on what effect this has. The University of York conducted a study on the impact of the consumption of plastic in salt on humans, they suggested the data available at the moment is inconclusive. Alistair Boxall, one of the co-authors of the study, said there is large a “knowledge gap” in existing research and that there so many different types of microplastics monitored across 320 separate studies that any type of data comparison is very hard to do.
Boxall said, "Based on our analysis, there is currently limited evidence to suggest microplastics are causing significant adverse impacts,” but this points more to a lack of data and a mismatch of data on the topic rather than any conclusive findings. Boxall added, “There is an urgent need for better quality and more holistic monitoring studies alongside more environmentally realistic effects studies on the particle sizes and material types that are actually in the environment.”
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