Investigation of meso- and microplastics in commercially sold dried pink shrimp in Ekiti State, South West Nigeria

Abstract

Microplastics (MPs) are a global problem due to their pervasiveness and possible harm to humans and other living organisms. It has been reported that a wide variety of foods, including seafood, contain microplastics. Dried pink shrimp (Penaeus notialis) popularly called ‘dried crayfish’ is a common delicacy in many Nigerian and West African local recipes. To our knowledge, this is the first study to assess the presence of meso- and microplastics in dried shrimp in Nigeria. From a survey of five popular markets in Ekiti State, South West, Nigeria—Shasha, Oja Oba, Agric Olope, Afao (Ikere), and Oja Isale (Ifaki), 15 samples of sun- and smoke-dried pink shrimp were purchased, and their meso- (5–25 mm) and microplastic (1 to < 5 mm) content was examined. Visual inspection showed that mesoplastic particles were present in all the dried shrimp types examined. A 10% KOH solution was used to digest the samples after they had been weighed. The samples were exposed to density floatation in KI solution, followed by filtration, drying, examination under a stereomicroscope, and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrophotometer. The mean concentration of mesoplastics per 10 g of sample was 2.13 ± 0.56 for sun-dried samples and 3.20 ± 0.90 for smoke-dried samples. Microplastics had a mean concentration of 6.47 ± 1.12 in sun-dried samples and 2.87 ± 0.90 particles/10 g in smoke-dried samples. Generally, the sun-dried shrimp showed a higher prevalence of microplastics than the smoke-dried samples. The ATR-FTIR results revealed the dominance of polyethylene, PE (80%) films and fibres, followed by styrene-butadiene rubber, SBR (12%), natural latex rubber, NLR (5%), and polyvinyl alcohol, PVA (2%). Polymer hazard index (PHI) denoted that PE microplastics had a PHI score of 877.8 classifying them in the hazard category IV which is a “danger” risk. The polymers may directly enter the human body when consumed via dried shrimp and cause health implications.