We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
Investigating microplastic release from plastic grinder heads during salt grinding
Summary
**TLDR:** Researchers found that plastic salt grinders release thousands of tiny plastic particles (called microplastics) into your salt when you grind it—with some grinders releasing over 15,000 particles per small container of salt. This means people may be eating more plastic particles than previously thought, since the grinder itself creates new plastic contamination beyond what's already in food from environmental sources. The study suggests using more durable materials for food grinders could help reduce how much plastic we accidentally consume.
Microplastic contamination of table salt has been widely reported, but most studies focus on environmental sources rather than microplastic release from food-contact materials under routine household use. Here, we demonstrate that commonly available plastic grinder heads themselves can be a significant contributor of microplastics in salt during household use. We tested commercially available salt products from different local retailers (Retailer A, B, and C), each fitted with plastic grinder heads, using a ceramic mortar as the control group. We implemented strict QA/QC measures, performing procedural blanks and calculating the recovery rate for spiked samples. Using optical photothermal infrared (O-PTIR) spectroscopy, we analysed subsampled particles visually detected on the collection filters and matched their spectra against the Hummel polymer library for identification. The grinder heads from the products were made of either polyethylene terephthalate (PET; Retailers A and B) or polycarbonate (PC; Retailer C), and the majority of microplastic fragments released corresponded to these polymers. Plastic grinder heads released a significant number of microplastic particles per 50 g salt (Retailer A: 1091 ± 239, Retailer B: 2420 ± 1805, Retailer C: 15743 ± 1858 particles, each Retailer n = 3 grinder heads), significantly higher than the procedural blanks results (The number of particles found in the experimental environment was 0, 1, and 0 respectively.). Microplastic particles released during salt grinding were confirmed using O-PTIR spectroscopy, with characteristic particle sizes on the order of several tens of micrometres (mean particle sizes ± standard deviation of 49.6 ± 18.2 μm n = 3 for Retailer A and 55.3 ± 12.7 μm n = 3 for Retailer B). Spectra collected from all particles, along with the associated QA/QC data, are openly available on Zenodo, contributing to transparency and reproducibility in microplastic research. In summary, our findings provide direct evidence that everyday food-contact plastics can introduce microplastics into diets, particularly under conditions of high mechanical stress, such as grinding. This highlights the need to assess the wear resistance of food-contact plastics and consider adopting more durable materials or designs to reduce consumer exposure to microplastics.
Sign in to start a discussion.
More Papers Like This
Determination of particle abrasion through milling with five different salt grinders – a preliminary study by micro-Raman spectroscopy with efforts towards improved quality control of the analytical methods
Researchers tested five salt grinders with plastic and ceramic burrs using micro-Raman spectroscopy, finding that plastic-burred grinders released thousands of polyoxymethylene and PMMA particles per 0.1 g of salt, far exceeding contamination from ceramic grinders. Even reference salt contained 423 plastic particles per 0.1 g before grinding, highlighting food processing equipment as a significant source of microplastic contamination.
Detection and Characterization of Microplastics in Commercial Salts in India
Researchers detected and characterized microplastics in commercial salts available in India, including rock salt, sea salt, and table salt varieties. The study found widespread microplastic contamination across salt types, raising food safety concerns given the ubiquity of salt as a dietary staple.
The presence of microplastics in commercial salts from different countries
Researchers analyzed 17 commercial salt brands from eight countries and found microplastic particles in all but one, with concentrations ranging from 1 to 10 particles per kilogram. The most common plastics were polypropylene and polyethylene, appearing mainly as fragments. While the estimated human intake from salt alone appears minimal, the study confirms that microplastics have infiltrated yet another everyday food product.
Determination of particle abrasion through milling with five different salt grinders – a preliminary study by micro-Raman spectroscopy with efforts towards improved quality control of the analytical methods
Researchers used micro-Raman spectroscopy to measure whether plastic and ceramic grinding burrs in salt mills shed microplastic particles into the salt during milling. Plastic burr mills released significantly more microplastic particles than ceramic ones, confirming that everyday food processing equipment can be a source of microplastic contamination in what we eat.
Determination of particle abrasion through milling with five different salt grinders – a preliminary study by micro-Raman spectroscopy with efforts towards improved quality control of the analytical methods
Researchers used micro-Raman spectroscopy to measure whether plastic and ceramic grinding burrs in salt mills shed microplastic particles into the salt during milling. Plastic burr mills released significantly more microplastic particles than ceramic ones, confirming that everyday food processing equipment can be a source of microplastic contamination in what we eat.