Um método simples e rápido para avaliação da contaminação por microplástico em sal comercial para consumo humano

Abstract

Microplastics are ubiquitous in all environments and can persist for hundreds of years. Human exposure to MPs can occur through the ingestion of food and beverages or inhalation of particles suspended in the air, posing a concern for human health. The aim of this study is to develop a simple, precise, and cost-effective methodology based on the identification of particles through optical microscopy to assess contamination by MP residues in salt for human consumption. This method was tested on six brands of salt, including five commercially refined salt brands and one analytical grade salt brand. To reduce counting errors, we used Bengal Rose dye, which absorbs on natural and non-plastic particles, aiding in their identification, and a classification criterion for particles identified as MP or suspected. This ensures that inherent errors associated with optical microscopy counting are always associated with underestimation rather than overestimation due to false positives. All salt brands were found to be contaminated, including the analytical salt PA (pro analysis). The number of identified particles ranged from 33.33 to 235.53 particles/kg in commercial salt and 91.06 particles/kg in analytical salt. Among the particles found, fibers accounted for 63%, while fragments accounted for 37% of the total. Our study was a preliminary analysis with a small sample size (n=6), without Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy to confirm the presence of microplastics. Nevertheless, our results suggest that Brazilian salt brands are contaminated with microplastics, and these particles are being ingested by humans.