According to a new study that observed sea, rock and lake salts, 90 percent of the table saltbrands sold around the world contain microplastics. Several years ago, researchers discovered that microplastics were in sea salt, but no one was certain just how extensive the problem was until now.

National Geographic reported that researchers in South Korea and at Greenpeace East Asia tested 39 salt brands, and 36 of them contained microplastics. This study — published in this month’s journal of Environmental Science & Technology — is the first of its kind to look at the correlation between microplastics in table salt and where we find plastic pollution in the environment.

Related: Study suggests the average person consumes 70,000 microplastic bits every year

“The findings suggest that human ingestion of microplastics via marine products is strongly related to emissions in a given region,” said Seung-Kyu Kim, a marine science professor at Incheon National University in South Korea.

The salt samples came from 21 countries in North and South America, Europe, Asia and Africa. The three brands that did not contain microplastics were refined sea salt from Taiwan, refined rock salt from China and unrefined sea salt produced by solar evaporation in France.

The density of microplastics in salt varied among the different brands. The study found that the tested Asian brands of salt contained the highest amounts, especially in the salt sold in Indonesia. An unrelated 2015 study found that Indonesia suffered from the second-worst level of plastic pollution in the world.

Researchers found that microplastic levels were highest in sea salt, followed by lake salt and rock salt. This latest study estimates that the average adult consumes about 2,000 microplastics each year through salt. But how harmful that is remains a mystery. Because of knowledge gaps and a mismatch of data in more than 300 microplastic studies, there is limited evidence to suggest that microplastics have a significant negative impact. Microplastics could be detrimental to our health and the planet, or the focus on microplastic could be diverting attention from worse environmental problems.

Via National Geographic

Image via Bruno