Microplastic contamination in commercial salt: An issue for their sampling and quantification.

Area of Science:

• Environmental Science
• Food Safety
• Analytical Chemistry

Background:

• Microplastics are emerging environmental contaminants with potential human health implications.
• Sea salt is a globally consumed food product, making it a potential pathway for microplastic ingestion.
• Previous studies have indicated the presence of microplastics in various food matrices, but specific data on sea salt, especially from major exporting regions like Italy, is limited.

Purpose of the Study:

• To quantify and characterize microplastic contamination in sea salt from Italian salterns.
• To identify the types of polymers present in the microplastics found in sea salt.
• To assess the potential of sea salt as a vector for microplastic exposure in humans.

Main Methods:

• Sea salt samples from three Italian salterns were dissolved in MilliQ water and filtered to isolate microplastics.
• Microplastics were visually quantified and classified by size and physical characteristics (shape) using a stereomicroscope.
• Polymer identification was performed using Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) spectroscopy and Raman spectroscopy.

Main Results:

• A significant concentration of microplastics was detected, averaging 1653 ± 29 microplastics per kilogram of sea salt.
• The majority of microplastics were found to be fibers (80.6%), followed by fragments (18.9%) and spheres (2.7%).
• The most prevalent polymer types identified were polypropylene, polyamide, and polyethylene, with most microplastics measuring between 0 and 500 µm.

Conclusions:

• Sea salt, particularly from Italian sources, represents a notable source of microplastic contamination.
• The physical characteristics and polymer types identified suggest potential environmental origins and pathways for microplastic entry into sea salt.
• Given the global export of Italian salt, this contamination poses a widespread risk to human health, necessitating further investigation and mitigation strategies.