Microplastics in Spanish Table Salt

Abstract

Marine debris is widely recognized as a global environmental problem. One of its main components, microplastics, has been found in several sea salt samples from different countries, indicating that sea products are irremediably contaminated by microplastics. Previous studies show very confusing results, reporting amounts of microparticles (MPs) in salt ranging from zero to 680 MPs/kg, with no mention of the possible causes of such differences. Several errors in the experimental procedures used were found and are reported in the present work. Likewise, 21 different samples of commercial table salt from Spain have been analyzed for MPs content and nature. The samples comprise sea salts and well salts, before and after packing. The microplastic content found was of 50–280 MPs/kg salt, being polyethylene-terephthalate (PET) the most frequently found polymer, followed by polypropylene (PP) and polyethylene (PE), with no significant differences among all the samples. The results indicate that even though the micro-particles might originate from multiple sources, there is a background presence of microplastics in the environment.

Microparticles in Table Salt: Levels and Chemical Composition of the Smallest Dimensional Fraction

“…Microplastic values recorded in this study are significantly lower than literature [37] and similar to 28-462 items/kg values recorded by Kim et al [38], and 50-280 items/kg by Iñiguez et al [35]. Our results are lower than 550-681 items/kg values recorded by Yang et al [34] in Chinese sea salts.…”

“…On a local scale, these activities could affect at different intensities both levels and chemical composition of microplastics in table salt of marine origin. Also, long exposure time to atmospheric deposition occurring during the evaporation process of water in salt marshes could determine significant differences concerning microplastic pollution due to local inputs from winds [35]. Concerning chemical composition of microplastics, Yang et al [34] reported that PET (polyethylene-terephthalate) is the principal component of plastic found in tested table salt and this fact is associated to the higher density of PET (1.30 g/cm 3 ) in comparison to PE (0.94 g/cm 3 ) and PP (0.90 g/cm 3 ) that allow PET deposition during the salt crystal formation.…”

“…The evaluation of risks associated with human health by the ingestion of microplastics <150 µm size represents the new frontier of medical researches [32]. Marine foodstuffs but, also, other human foods coming from the sea such as canned fishes [33] and marine salts [31,[34][35][36][37] are affected by microplastics. Different salts types are commercialized worldwide.…”

“…Different salts types are commercialized worldwide. As reported by Iñiguez et al [35], different processes are used to produce salt: mining (rock salt), water evaporation (lake and sea salt), and wells in non-coastal zones (river and well salts). Salts from marine origin were tested by recent researches and they resulted polluted by microplastics.…”

Particle and salinity sensing for the marine environment via deep learning using a Raspberry Pi

“…They have been found in fish and bivalve organisms, and have been shown to have negative effects on zooplankton and oysters [11][12][13][14][15][16]. Table salt from around the world has been found to contain microplastics [17,18], and the sea salt contamination, by plastic itself, has been shown to be an indicator of plastic pollution. Drinking water can also contain microplastics [19], and the potential impact on humans has been discussed [20,21], with specific negative impacts on epithelial inflammation [22] and muscle cell behaviour [23].…”