Sea salt has enjoyed a stellar reputation in the culinary world. Marketed as a natural, minimally processed alternative to standard table salt, it is a staple in kitchens everywhere. But as our oceans become increasingly burdened with plastic waste, sea salt is hiding an invisible, unappetizing ingredient: microplastics.
The evaporation process
To understand why sea salt is so susceptible to microplastic contamination, we have to look at how it is made. The production of sea salt relies on an ancient, simple mechanism, namely solar evaporation.
Saltwater is pumped from the ocean into large, shallow pools known as evaporation ponds. As the sun and wind do their work, the water slowly evaporates, leaving behind concentrated brine and, eventually crystallized salt that can be harvested.
The problem lies in what else is floating in that ocean water. Our seas are filled with microscopic plastic debris in the form of fragments from broken-down bottles, synthetic clothing fibers, and industrial microbeads. When the ocean water evaporates, it doesn't take the plastic with it. Instead, those tiny fragments of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) are trapped within the salt.
What is hiding in your salt shaker?
The sheer scale of microplastic contamination in sea salt might surprise you. When researchers started testing commercial salt brands, the results were staggering:
- Studies have found that over 90% of sampled salt brands worldwide contain microplastic particles.
- Because sea salt is harvested directly from coastal waters, it carries the highest burden of any salt type, sometimes containing up to 1674 microplastic particles per kilogram.
- Researchers estimate that an average adult consuming standard amounts of salt ingests roughly 2000 microplastic particles every year from salt alone.
Sea salt versus rock salt, is there a cleaner option?
Not all salt is created equal when it comes to microplastic exposure. Because contamination levels correlate directly with the pollution in surrounding waters, the origin of your salt matters immensely.
While sea salt is heavily impacted by modern marine pollution, rock salts such as Himalayan pink salt, are mined from ancient sea beds that dried up millions of years ago. Because these salt deposits formed long before the invention of synthetic plastics, rock salts generally show the lowest levels of microplastic contamination, often testing between 0 and 148 particles per kilogram, compared to the thousands found in sea salt.
Switching to rock salt or deeply mined well salts is a simple, effective swap for those looking to reduce their dietary exposure to microplastics. Until we can clean up our oceans, our sea salt will continue to reflect the environment it comes from, microplastics and all.
Sources
- Greenpeace East Asia & Incheon National University. Over 90% of sampled salt brands globally found to contain microplastics.
- Environmental Science & Technology. Comprehensive analysis of microplastics in commercial salt, noting up to 1,674 particles/kg in sea salt.
- Scientific Reports. Microplastics in Spanish Table Salt, detailing the evaporation process and prevalence of PET, PP, and PE polymers.
- Body Burden Lab. Microplastics in Salt: Is Sea Salt Making You Eat More Plastic?
