A study of the microplastic contamination of commercial table salts: A case study in Nigeria

Background: Environmental pollution caused by microplastics (MPs) is quite ubiquitous and has become a global issue. Several studies have focused on MPs in marine and freshwater systems. However, there is a paucity of data about the presence of MPs in sea products like table salt and the risks they likely pose. Hence, this study investigated the presence of MPs in commonly consumed commercial table salts in South-West, Nigeria. Methods: A total of 8 different brands of commonly consumed commercial salts were purchased from open supermarkets in Ogun and Lagos States, Nigeria. Salt samples were digested with 30% H2O2, extracted for MPs, and observed under a digital microscope for shape, quantity, and colour. Results: Fibres and fragments were the plastic shapes found in the samples, with fibres being more prominent. The average content of MPs obtained was 12 particles/kg. Blue, pink, and purple colours of MPs were commonly found. The sizes of MPs were between 50 μm and 1 mm. Considering our findings and based on the World Health Organization's (WHO's) recommended daily intake of 5 g of salt, Nigerian adults will consume an average rate of 21.9 microplastic particles/year. Conclusion: According to the results of the study, table salts commonly consumed in Nigeria are polluted with MPs. Due to the importance of table salt as related to daily food intakes, it becomes very necessary to fine-tune technologies in their production to improve the quality and lower MPs ingested by consumers in Nigeria.