Check your salt grinder. The part that actually grinds it might be plastic
Kirkland shoppers found black plastic flecks in their pink salt grinder. Lab tests show plastic burrs shed thousands of particles per gram - here's what to check and the cheap fix.
Emily Harper
Check the part of your salt grinder that actually touches the salt. On most of the ones sold pre-filled at the grocery store, it's plastic - and every twist of the cap is filing a little of it into your food.
What people are finding in their own kitchens
Shoppers online have documented black plastic specks coming out of Kirkland Signature's pink Himalayan salt grinder - a lid Costco sells as an "adjustable ceramic" grinder - after noticing dark flakes mixed in with the salt or floating in saltwater made from it. Tasting Table covered the pattern: multiple people reporting the same black flaking from the same product, with no recall and no public response from Costco. Kirkland isn't unique. Most disposable grinders that come pre-filled at the store use polymer burrs - usually POM, polystyrene or PMMA - because plastic is cheap to injection-mold into that shape. Hard salt crystals and peppercorns then abrade that plastic every single turn, for as long as the grinder is used.
What the actual lab testing shows
Two separate studies have measured this directly. A 2020 study milled reference salt through five different grinders and analyzed the ground salt under micro-Raman spectroscopy: the two grinders with POM burrs shed roughly 5,000 to 7,600 microplastic particles per 0.1 gram of salt milled - meaning tens of thousands of particles per gram - while a PMMA grinder shed about 2,400 particles per gram. A more recent 2026 study on retail plastic grinder heads found 1,091 to 15,743 particles per 50 grams of salt, depending on the brand, made mostly of PET and polycarbonate matching the material of each grinder's housing. Both studies and their figures are summarized here. The particle counts track the material: a POM burr sheds POM, a PET housing sheds PET. The plastic in the grinder is the plastic in your food.
And that's on top of contamination the salt already carries before it's ever ground. A global survey of 39 salt brands across six continents, published in Environmental Science & Technology, found microplastics in over 90% of them, with sea salt carrying the most and rock salt the least - a rough proxy for how much plastic pollution sits in the water or ground the salt was harvested from.
Why the amount might matter more than it sounds
Two recent studies on where ingested plastic actually ends up are why "a few plastic flecks in your salt" is worth taking seriously instead of shrugging off. A March 2024 New England Journal of Medicine study examined carotid artery plaque removed from 257 patients during surgery and found microplastics or nanoplastics embedded in the plaque of 58% of them - mostly polyethylene, some PVC. Over the next 34 months, those patients had 4.5 times the rate of heart attack, stroke or death compared to patients whose plaque had none. The study can't prove the plastic caused the difference, but it's the first time this association has shown up in real patient outcomes, not just a lab dish.
Separately, a February 2025 Nature Medicine study analyzed frontal-cortex brain tissue from autopsies performed in 2016 and in 2024. Researchers found the average brain now carries roughly 7 grams of micro- and nanoplastics - about the mass of a plastic spoon - which is roughly 50% more than the 2016 samples held, and brain tissue carried a higher concentration than liver or kidney tissue from the same bodies. Neither study can point to your salt grinder specifically as a source; the plastic these researchers found could have come from packaging, water, dust or dozens of other everyday sources. But a device that mechanically shaves plastic into your food, every day, for as long as you own it, is one of the more avoidable ones.
The fix costs nothing extra
You don't need to give up ground salt. Open the grinder and feel the part that actually grinds: ceramic or stainless/carbon steel doesn't shed particles the way molded plastic does. Peugeot's mills use a mechanism forged from a single piece of case-hardened carbon steel, and most refillable mills use steel or ceramic for the same reason. If the grinder you already own turns out to have a plastic burr - the McCormick and Great Value grinders both use plastic housings - the cheapest fix isn't buying another disposable one. It's refilling the same reusable mill with bulk salt instead.
What this actually tells you
- The packaging material is the tell, not the label. "Ceramic grinder" printed on a cap describes the housing, not necessarily the burr doing the actual grinding - open it and check.
- The dose is unusually literal here. Most microplastic exposure is diffuse and hard to trace to one source. A plastic burr grinding against salt crystals every time you use it is a mechanism you can see and stop.
- Refillable beats disposable for more than the obvious reason. A steel or ceramic mill you refill for years isn't just less plastic waste - it's a grinder that was never going to shed plastic into your food in the first place.
Before you buy the next jar, scan the barcode on Tallow - it flags seed oils, additives and lab-tested contaminants on the product itself, so you're not left guessing what else in the pantry has a similar problem.
Figures and facts in this post are sourced from the peer-reviewed studies, medical journals and press coverage linked above, current as of the time of writing. This is not medical advice.