A new study looked at sea, rock, and lake salt sold around the world. Here’s what you need to know.

Microplastics were found in sea salt several years ago. But how extensively plastic bits are spread throughout the most commonly used seasoning remained unclear. Now, new research shows microplastics in 90 percent of the table salt brands sampled worldwide.

Of 39 salt brands tested, 36 had microplastics in them, according to a new analysis by researchers in South Korea and Greenpeace East Asia. Using prior salt studies, this new effort is the first of its scale to look at the geographical spread of microplastics in table salt and their correlation to where plastic pollution is found in the environment.

“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.