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Investigating microplastic release from plastic grinder heads during salt grinding
Cihang Yang1, Kangti Li1, Aoife Gowen1
1School of Biosystems and Food Engineering, University College Dublin, Belfield, Dublin 4, Ireland.
The Science of the Total Environment
|February 25, 2026
Summary
Plastic grinder heads are a significant source of microplastics in table salt during household use. This study found that common plastic grinders release thousands of microplastic particles, highlighting risks from food-contact materials.
Area of Science:
- Environmental Science
- Materials Science
- Food Safety
Background:
- Microplastic contamination in table salt is a known issue, but sources from food-contact materials during domestic use are understudied.
- Previous research primarily focused on environmental origins of microplastics in salt.
Purpose of the Study:
- To investigate microplastic release from plastic salt grinder heads during typical household use.
- To quantify microplastic generation from different plastic grinder materials (PET, PC).
Main Methods:
- Commercially available salt grinders with plastic heads were tested against a ceramic mortar control.
- Optical photothermal infrared (O-PTIR) spectroscopy was used for microplastic identification and quantification.
- Rigorous quality assurance, including procedural blanks and recovery rate calculations, was implemented.
Main Results:
- Plastic grinder heads released significant quantities of microplastics (1,091–15,743 particles per 50g salt), far exceeding procedural blanks.
- Microplastics identified were consistent with grinder head materials: polyethylene terephthalate (PET) and polycarbonate (PC).
- Released microplastic particles had sizes in the tens of micrometres range.
Conclusions:
- Everyday food-contact plastics, like salt grinder heads, can be a direct source of microplastics in consumer diets.
- Mechanical stress during use, such as grinding, exacerbates microplastic release from these materials.
- There is a need to evaluate the wear resistance of food-contact plastics and develop more durable alternatives to minimize consumer exposure.
