Traces of microplastics have been found to be included in packs of salt used for cooking, suggesting that the toxic substance is likely ingested with the food that people eat.
Researchers at the State University of New York (SUNY) Fredonia discovered that at least 15 different brands of sea salt sold in China contain as much as 550 to 681 particles of microplastic for each kilogram, which is twice as much as that found in lake salt packs and thrice as much as that found in rock salt packs.
The discovery of microplastics in Chinese salt packs raises concerns about the possibility that plastic particles may also be included in brands available in supermarkets in the United States.
"Plastics have become such a ubiquitous contaminant, I doubt it matters whether you look for plastic in sea salt on Chinese or American supermarket shelves," SUNY researcher Sherri Mason said. "I'd like to see some 'me-too' studies."
Emma Johnston, a director at the Sydney Institute of Marine Science in Australia, echoes Mason's sentiments, stating that what researchers have to determine is how much of the synthetic material could potentially cause problems to people.
The researchers estimate that a person who consumes an average of five grams of salt per day ingests as much as 1000 particles of microplastic every year.
The SUNY Fredonia study is the first of its kind to show microplastic contents included in food sources, but according to Johnston, scientists in Australia have already known that the toxic substance affects fish in the country.
She said that they have detected high concentrations of microplastics in Sydney Harbor, finding the synthetic material in 100 different marine species including fish, mussels and oysters.
The issue becomes even more problematic when producing salt supply as the low concentrations of microplastics in ocean water often become higher when it is turned into sea salt.
Johnston said that this is a cause for concern since microplastic can also bind to flame-retardant substances and metals.
"They accumulate [up the food chain] and some are endocrine disrupters," Johnston explained. "The bound contaminants release in our guts."
Scientists have discovered that microparticles consumed by mussels and worms can potentially cause inflammatory responses and diseases in the marine organisms.
The findings of the State University of New York Fredonia study are featured in the journal Environmental Science and Technology.
Photo: Kevin Dooley | Flickr