Waste generation and disposal, particularly of plastics, have grown significantly over time due to the rapid expansion of urban development. Aquatic species are especially threatened by plastic pollution because the aquatic ecosystem serves as a sink for all contaminants. The capacity for regular development and reproduction is crucial for both human and wildlife health. The endocrine system, which comprises numerous glands that emit hormones to control blood sugar, growth, reproduction, metabolism, and the development of the brain, normally controls these functions. The majority of the synthetic organic chemicals used in plastics come from petroleum. It is well known that their effects cause the endocrine system's regular operation to be disrupted. Plastics are produced at a low cost, and their light weight and adaptability make them candidates for a wide range of uses in all facets of daily life. Plastic waste can enter the ecosystem through waste discharges from oil and gas platforms, aquaculture, and landfills, as well as through litter such as bags and plastic bits used as abrasives. Because they include indigestible particles that fill the stomach and lessen appetite, plastics have been implicated in harming the health of a variety of creatures. They were also discovered in the gastrointestinal tract of individual fish after one week, which disrupted the food's flow to the intestinal mucosa and had an impact on the fish's growth and physical condition. Additionally, fish exposed to plastics have been shown to exhibit changed behavior, decreased sperm motility, and increased thyroid hormone production. Therefore, exposure to varied amounts of polyethylene impairs an organism's normal physiological functioning and has the potential to impact negatively on both the health of the organism and its offspring. This review was aimed at highlighting the risks of plastic exposure to fish and people through the food chain.

The present study assessed the effects of human pressure on the surface water quality of the Ogbor Hill River, southern Nigeria. This river is among one of the important rivers in Southeast Nigeria for domestic, agricultural and industrial purposes. To assess the water quality, samples of water were collected monthly for eight months, and were preserved and transferred to the laboratory for further analysis. Electrical conductivity, pH, total dissolved solids, salinity, turbidity and temperature were determined in situ. Other parameters were determined in the laboratory using standard laboratory methods. The results revealed that the mean pH was acidic across the months with no significance difference (p > 0.05). Additionally, the mean total dissolved solids showed a significant difference (p < 0.05), with a higher value of 582.10 ± 83.41 in April and a lower value of 243.67 ± 40.62 in May. The highest mean conductivity of 1392.33 ± 156.18 was observed in April, and the lowest mean of 289.33 ± 97.37 in May. Dissolved oxygen indicated there was a significant difference among the study months (p < 0.05), with the highest mean concentration of 4.80 ± 0.37 in June and the least of 3.30 ± 0.20 in April. Biochemical oxygen demand, chloride and temperature all showed a significant difference (p < 0.05) across the sampling months. The mean concentration of Zn showed no significant difference among the study months. The mean concentration of Fe recorded showed the highest value of 2.68 ± 0.16 in April and the lowest mean of 1.96 ± 0.13 in July. Pb showed a higher concentration of 0.44 ± 0.33 in March and a lower mean of 0.033 ± 0.008 in July. A higher mean Cd of 0.052 ± 0.004 was observed in March and a lower mean of 0.023 ± 0.002 in December. Generally, the water parameters were elevated beyond the threshold for surface water, which was an indication that the river water was badly impacted due to human pressure and needed to be kept safe for human use. The present study revealed that most of the water quality parameters such as TDS, DO, BOD, pH, turbidity, and concentrations of the heavy metals Pb and Cd were higher in selected months, and further water management should be carried out while anthropogenic activities should be reduced around the river ecosystem.

Due to rapid urbanization, increase in coastal population, oil and gas exploration and other array of anthropogenic activities within the Niger Delta region of which Rivers and Bayelsa states are prominent amongst others, the region has been faced with coastal water pollution. There is need therefore, to evaluate the intensity of environmental contamination of the aquatic ecosystem in this region, thus this study was conducted to investigate the heavy metal levels of Clams (Egeria radiata) sold in open markets in Port Harcourt (Rivers State) and Yenagoa (Bayelsa State). Samples were collected from three markets in Port Harcourt (Mile 1, Rumuokoro and Mile 3), and three markets as well in Yenagoa (Opolo, Swali and Tombia) respectively. The samples were collected bi-weekly for 3 months and transported to the laboratory for analysis of heavy metals (Cr, Cd and Pb) levels using standard scientific method of analysis. The analysis was done in triplicates for each sample and data obtained were subjected to statistical analysis using excel spreadsheet and statistical package for social sciences (SPSS) version 21. The results revealed that samples collected from markets in Port Harcourt had higher concentrations of heavy metal than that of Yenagoa, though, the heavy metal levels were below World Health Organisation permissible limits, except for Cadmium (Cd) that ranged from 0.54±0.002 to 0.78±0.00 mg/kg in samples collected from Port Harcourt, against 0.5 mg/kg recommended by WHO. This could be attributed to oil and gas exploration, and discharges of industrial and domestic wastes bearing cadmium, and poses serious health risks. Therefore, routine monitoring and assessment of the aquatic ecosystem will be vital to forestall further contamination.

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