Variability in microplastic abundance, bisphenol A contamination, antioxidant properties, and health risks associated with vegetable consumption

Background

Plastic pollution, particularly microplastics (MPs) and toxic additives such as bisphenol A (BPA), endangers human health. Therefore, their routes in the environment need to be investigated. This study investigated microplastic (MPs) abundance, bisphenol A (BPA) levels, and antioxidant activity (AA) in three commonly consumed vegetables—green amaranth, jute mallow, and spinach sourced from two markets in Osogbo, southwestern Nigeria. Microscopic technique was used to determine MP abundance, shapes, and colours. High-performance Liquid Chromatography (HPLC) was used to analyse BPA contents while 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to measure AA. A hazard index (HI) and estimated dietary intakes (EDIs) were used to estimate the associated risks and food safety concerns with MP and BPA in vegetables.

Results

In this study, MP abundance in shoots ranged from 4.00 ± 0.50 to 7.67 ± 1.04 particles/g and in roots from 5.33 ± 1.53 to 18.00 ± 6.93 particles/g in spinach and green amaranth, respectively, indicating subsoil contamination. Three shapes (fragment, fibre, and irregular) and five colours (transparent, white, yellow, black, and brown) were detected, with fragment shape and transparent colour dominating. Fourier Transform Infrared spectroscopic (FTIR) analysis revealed a predominance of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, and polyamide microplastics. The BPA ranged from 5.55 ± 0.56 to 6.65 ± 0.00 μg/g while AA ranged from 40.67 ± 6.79 to 72.55 ± 4.03%. A regression analysis and principal component analysis (PCA) were used to identify the relationship among the factors (MPs, BPA, and AA). It is suggested that high levels of MPs and BPA negatively impacted vegetable quality as they are associated with environmental contamination. Contrastingly, AA had a significant positive correlation with vegetable quality. Both EDIs and HI of MPs and BPA were < 1, indicating no significant risk associated with BPA exposure from their consumption.

Conclusion

This study highlights the potential health risks of MPs and associated BPA contamination in vegetables. The estimated dietary intake and hazard index suggest no immediate health risks, but long-term exposure remains a concern. MPs and BPA in commonly consumed vegetables warrant stricter monitoring of agricultural soil and irrigation water sources. Microplastic exposure in food crops can be reduced with policies that regulate plastic waste disposal and promote sustainable farming practices.