# Microplastic Pollution: Chemical Characterization and Impact on Wildlife
## 3 Microplastics and Wildlife
### Microplastics in Aquatic Animals
During the autopsy, evident microplastics and intestinal blockage were checked in the stomach and intestinal contents. A chemical study was carried out to look for the presence of MP in internal organ tissue. All the animals' livers, stomach walls, intestines, and a large section of muscle were sampled for chemical tests. The largest portion of the pectoral muscle (_M. pectoralis_ major) was removed from birds, the central dorsal fillet behind the dorsal fin from fish, and the internal muscle of the back (_M. iliosposa_) from mammals. Additionally, samples of fish gills, otters' spleens, and the kidneys of birds and mammals were taken. A lung fragment from the harbor seal was also examined. The animals' stomachs were opened, and the intestines were cleaned out and examined for large plastics that might have an impact on the animals' health and well-being. Using a tiny glass funnel, the intestines were rinsed thoroughly with 50-100 mL of saline. Prior to the examination, samples were weighed, wrapped in aluminum foil, and kept frozen at 20 \({}^{\circ}\)C. The two sawbill ducks, which are seabirds, had intestines with MPs of PVC and PS of roughly the same concentrations, whereas the guillemot had detectable amounts of MP in the stomach (PVC) and liver (PET), but no MP in the intestinal tissue. However, cod was the only species for which repeated samples were examined. Of all the animals, cods exhibited the highest frequency and tissue concentrations of MP. MP was present in all three tissues--liver, muscle, and intestines--in two of the three cods. Only one sample of muscle and no other tissues from flounders had MP. At least one tissue sample from 8 of the 13 examined animals contained measurable MP levels. Four separate animals had measurable MP levels in their muscles and/or liver, whereas seven of the eight animals had MP in their intestines or stomach walls. The Cod liver has the greatest concentration of MP in any tissue, at 3.4 per gram wet weight. Polyvinyl chloride (PVC)-type microplastic can alter the antioxidant activities and inhibit the growth rate of fish larvae (_Cyprinus carpio_). [PERSON] et al., 2020, investigated the exposure of PVC in freshwater fish larvae and found microplastics significantly inhibit the growth and inverse relationship found in SOD (superoxide dismutase) and CAT (catalase) activities [80]. A control group (no PVC microplastics) and three further groups (each with varying PVC microplastic contents of 10%, 20%, and 30% microplastics by weight) were set up for the 30-day and 60-day food exposure studies. According to these concentrations, there were 45.55 g, 91.1 g, and 136.65 g of microplastics per liter of water, respectively. Enzymatic activities and protein concentrations were assessed after the 30- and 60-day trials using the livers, intestines, and gills that had been removed from 12 fish in the control group and for each concentration. Four different fish tissues were taken out and mixed. Using an OxiSelect SOD Activity Assay kit from Cell Biolabs (STA-340), a CAT Assay kit from Solarbio (BC0200), a Micro GPX Assay kit from Solarbio (BC1195), and an MDA Assay kit from Solarbio (BC0025) the activities of SOD (superoxide dismutase), CAT (catalase), GPx (glutathione per-oxidase), and MDA (malondialdehydedehyde) levels, respectively, were determined for the livers, intestines, and gills. After 30 and 60 days of exposure, the liver, gut, and gills were examined for SOD, CAT, GPx, and MDA levels. The findings showed that after 30 days of exposure, all treated groups' liver SOD activity considerably decreased in comparison to the control group. However, compared to the control group, the SOD activities in the gills and intestines were initially significantly increased in the 10% PVC concentration group and thereafter decreased in the other PVC concentration groups. In contrast to the control group, the SOD activity in the livers, intestines, and gills were considerably reduced after 60 days of exposure in all exposure groups.