Microplastic Pollution in Table Salts from China

TLDR

Microplastics are ubiquitous in marine environments worldwide. The study tests whether sea salts contain microplastics due to their seawater origin. The authors sampled 15 brands of sea, lake, and rock/well salts from Chinese supermarkets to assess microplastic contamination. Sea salts contained 550–681 particles/kg, far exceeding lake (43–364) and rock/well (7–204) salts, with fragments/fibers predominating, most particles <200 µm, mainly polyethylene terephthalate, indicating significant microplastic contamination and marking the first report of such pollution in abiotic sea products.

Abstract

Microplastics have been found in seas all over the world. We hypothesize that sea salts might contain microplastics, because they are directly supplied by seawater. To test our hypothesis, we collected 15 brands of sea salts, lake salts, and rock/well salts from supermarkets throughout China. The microplastics content was 550-681 particles/kg in sea salts, 43-364 particles/kg in lake salts, and 7-204 particles/kg in rock/well salts. In sea salts, fragments and fibers were the prevalent types of particles compared with pellets and sheets. Microplastics measuring less than 200 μm represented the majority of the particles, accounting for 55% of the total microplastics, and the most common microplastics were polyethylene terephthalate, followed by polyethylene and cellophane in sea salts. The abundance of microplastics in sea salts was significantly higher than that in lake salts and rock/well salts. This result indicates that sea products, such as sea salts, are contaminated by microplastics. To the best of our knowledge, this is the first report on microplastic pollution in abiotic sea products.