Occurrence, distribution, source apportionment, ecological and health risk assessment of heavy metals in water, sediment, fish and prawn from Ojo River in Lagos, Nigeria

The study investigates the occurrence and bioaccumulation of heavy metals in water, sediment, fish, and prawn from the Ojo River with a view to identify the source of origin and the associated ecological and human health risks. The result shows that heavy metal concentrations in water [As = 0.010, Cd = 0.001, Cr = 0.041, Cu = 0.019, Co = 0.050, Fe = 0.099, Pb = 0.006, Ni = 0.003, and Zn = 0.452(mg/L)] were within the acceptable limits. The heavy metals in the sediment [As = 0.050, Cd = 0.287, Cr = 0.509, Cu = 0.207, Co = 0.086, Fe = 33.093, Pb = 0.548, Ni = 0.153 and Zn = 4.249 (mg/kg)] were within their respective background levels or earth's crust and the TEL and PEL standard limits. The bioaccumulation of heavy metals in fish and prawn tissues are in this hierarchical form: Fe > Zn > Cu > Cr > Ni > Co > Pb > Ar > Cd and Fe > Zn > Cu > Cr > Pb > Ar > Ni > Co > Cd, respectively. The bioaccumulation factors of heavy metals in fish ranged from 0.893 - 16.611 and 1.056 - 49.204 in prawn, which were higher than the biota-sedimentation factors (BSAF) values, inferring that the fish and prawns of this study ingested heavy metals highly from water column. The aggregated BSAF scores (fish = 5.584 and prawn = 9.137) showed that these organisms are good concentrators of heavy metals in sediments. The water quality index and other pollution indices (Single pollution index, Heavy metal assessment index, and Heavy metal pollution index) demonstrates slightly clean water, with a moderate level of contamination. The HI values of heavy metals in water, fish, and prawn were lower than 1, implying non-carcinogenic risk in children or adults. The ADD and EDI values of the metals were within their respective oral reference doses (RfD). The TCR values showed that exposure to water, either by ingestion or dermal absorption and the consumption of P. obscura and M. vollenhovenii from the Ojo River would not induce cancer risks in people, though As, Cr, Cd, and Pb showed carcinogenic potentials. The sediment contamination indices such as CF, mCd, EF, and Igeo showed a moderate level of pollution. The ecological risk values (NMPI, mCd = 0.068, PLI = 0.016, and R.I = 86.651) of heavy metals implies "no-moderate risk" except for Cd, which showed high risk. The ecotoxicological parameters,  m-PEL-Q (0.024) and m-ERM-Q (0.016) denotes low contamination and no probability of acute toxicity. The CV analysis showed high dispersions and variabilities in the distributions of the heavy metals in water. Other source analyses (Pearson's correlation matrix, PCA, and HCA) showed that both natural processes and anthropogenic activities are responsible for the occurrence of heavy metals in water and sediment from the Ojo River.

Total Mercury and Fatty Acids in Selected Fish Species on the Polish Market: A Risk to Human Health

The muscles of lake trout (Salvelinus namaycush Walbaum, 1792), crucian carp (Carassius carassius Linnaeus, 1758), flounder (Platichthys flesus Linnaeus, 1758), gilthead seabream (Sparus aurata Linnaeus, 1758), mackerel (Scomber scombrus Linnaeus, 1758) and tench (Tinca tinca Linnaeus, 1758) were examined. The total mercury (THg) was processed using the Milestone DMA-80 and the fatty acids were analyzed using the 7890A Agilent Technologies chromatograph. The THg content in analyzed fish ranged from 0.024 (lake trout) to 0.092 mg/kg wet weight (gilthead seabream). The muscles of fish examined had lower amounts of SFAs, and n-3 and n-6 PUFAs than MUFAs. The ratio of n-3/n-6 was higher in muscles of mackerel than other fish (p < 0.05). Due to the fact that both the THQ and HI are below 1, the tested fish are safe for the consumer from a nutritional point of view. Similarly, fatty acid indices indicate the safe consumption of selected fish species, and the daily consumption of the recommended dose of EPA + DHA (250 mg/day) and the concentration of mercury in fish calculations showed a hazard quotient for the benefit−risk ratio HQEFA below 1, suggesting that the intake of EPA + DHA poses no evident risk to human health. The ratio was calculated for a person weighing 60 kg. Therefore, it is important to monitor the fish, not only bought in the store, but also caught in various aquatic environments.

Multi-metric Ecosystem Health Assessment of Three Inland Water Bodies in South-west, Nigeria, with Varying Levels of Sand Mining Activities and Heavy Metal Pollution

This study was conducted to determine the health status of three water bodies (Badagry Creek, Ologe Lagoon and River Owo) exposed to varying degrees of sand mining activities and industrial pollution. Water, sediment and fish samples were collected monthly from the three water bodies between April 2019 and March 2020. Standard methods were used for the analysis of physico-chemical parameters, fish diversity indices, length-weight relationship, condition factor, sediment pollution indices, ecotoxicology of heavy metals in sediment, potential ecological risks and health risk assessment of heavy metals. Positive matrix factorization (PMF) was used to identify and quantify metal source. Shannon's diversity index (H') and condition factor varied between 2.03-2.37 and 0.84-4.86 respectively. Enrichment factor had a range of 4.05×10^-4-8.65×10^-1, while geoaccumulation index varied from -12.14 to -0.38. The mean quotients using the probable effect level (m-PEL-Q) are 3.91×10^-4, 4.77×10^-4 and 7.87×10^-4 for Ologe Lagoon, Badagry Creek and River Owo respectively. The trend was the same with mean quotients using effect range-median (m-ERM-Q). The estimated dietary intake ranged from 0.00 mg/kg/day in Pb from River Owo to 1.15 × 10^-3 mg/kg/day in Fe still from River Owo. The range of values of the target hazard quotient of the metals in Badagry Creek, River Owo and Ologe Lagoon are 1.23×10^-4-1.65×10^-2, 0.00-1.64×10^-2 and 5.76×10^-5-1.65×10^-2 respectively. PMF identified three sources of metal into the aquatic ecosystems: agricultural, industrial and geological inputs. The study showed that the three aquatic ecosystems are healthy but require regular monitoring to promptly detect sudden changes in their health status.

Assessment of Fish Quality Based on the Content of Heavy Metals

The aim of this study was to estimate the fish quality in terms of the Cu, Fe, Mn and Zn contents. The research material was the muscle tissue of the fish crucian carp (Carassius carassius Linnaeus, 1758), flounder (Platichthys flesus Linnaeus, 1758), Gilthead seabream (Sparus aurata Linnaeus, 1758), mackerel (Scomber scombrus Linnaeus, 1758), Blue grenadier (Macruronus novaezelandiae Hector, 1871), rainbow trout (Oncorhynchus mykiss Walbaum, 1792), tench (Tinca tinca Linnaeus, 1758), tilapia (Oreochromis niloticus Linnaeus, 1758), Walleye pollock (Gadus chalcogrammus Pallas, 1814) and perch (Perca fluviatilis Linnaeus, 1758.). Heavy metals were determined with the atomic absorption spectrometry method (AAS). Significantly high concentrations of zinc (19.52 mg/kg wet weight), copper (0.77 mg/kg) and iron (6.95 mg/kg) were found in the muscles of crucian carp (p < 0.05) compared to the other fish studied, whereas Walleye pollock had a higher content of manganese (0.266 mg/kg) (p < 0.05). All studied fish species do not pose a threat to humans from these four metals. This was indicated by quality indexes (THQ and HI) whose values were below one. The values of these metals also did not exceed the maximum allowable concentrations established by the FAO (1983), but monitoring both the aquatic environment and the fish living there is necessary, for example, for the time-changing abiotic and biotic factors that can cause an increase in metals in the organs of fish.

Aquatic food animals in the United States: Status quo and challenges

This review summarizes (1) the U.S. status quo for aquatic food animal production and marketing; (2) major food safety and quality issues/concerns for aquatic food animals in the United States, including fish misbranding, finfish/shellfish allergies, pathogens, toxins and harmful residues, microplastics, and genetically engineered salmon; and (3) various U.S. regulations, guidances, and detection methods for the surveillance of fishery products. Overall, fish misbranding is the biggest challenge in the United States due to the relatively low inspection rate. In addition, due to the regulatory differences among countries, illegal animal drugs and/or pesticide residues might also be identified in imported aquatic food animals. Future regulatory and research directions could focus on further strengthening international cooperation, enhancing aquatic food animal inspection, and developing reliable, sensitive, and highly efficient detection methods.

Insights into the heavy metal-induced immunotoxic and genotoxic alterations as health indicators of Clarias gariepinus inhabiting a rivulet

There is a dire need to assess the quality of fishes transported for human consumption as lately, their health is challenged because of anthropogenic activities. Heavy metals with a long environmental persistence are toxic to fishes and the humans. The study was conducted to evaluate the impact of heavy metals on Clarias gariepinus inhabiting popular Ganges rivulet at Narora (28.18° E, 78.39° N). The limnological values deviated from the international Standards (USEPA, WHO). Higher total dissolved solids (859 mg/L), total suspended solids (406 mg/L), low dissolved oxygen (5.60 mg/L), and pH (5.21) indicated the presence of contaminants. Heavy metals estimated followed the order Cd > Ni > Cu > Cr. Serum enzymes (hepatic and renal markers) viz., aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were higher than the normal, whereas, creatine kinase (CK) was considerably low in both male and female fish. Stress induced was marked by elevation in cortisol and glucose. This had its impact on hematological parameters as well, as a decline in Total leucocyte count (TLC) & mean corpuscular volume (MCV) and increase in Mean cell hemoglobin (MCH) was observed. Erythrocytes also showed altered morphology. Marked histopathological alterations were observed in all immune organs (head-kidney, liver, spleen, thymus). Oxidative stress induced by heavy metals leads to the production of metal scavenging protein metallothionein (MT) and glutathione peroxidase (GPX). Maximum fold change in metallothionein (MT) gene expression was observed in the liver, followed by spleen, thymus, blood, and head-kidney. Glutathione peroxidase (GPX) gene expression was highest in the liver, followed by thymus, spleen, blood, and head-kidney. The gene expression studies further validated the increased level of heavy metals as potent contaminants of water and the non-condusive abiotic factors.

Heavy Metal Contamination in Fish (Callinectis amnicola) From an Estuarine Creek in the Niger Delta, Nigeria and Health Risk Evaluation

Heavy metal bioconcentration in crabs from an estuarine creek in the Niger Delta was examined using atomic absorption spectrophotometry. Health risk via human exposure to metal toxicity was evaluated. Mean metal levels (µg/g) were Cr 2.32 ± 0.71, Ni 2.76 ± 0.48, Cu 12.94 ± 3.53, Pb 5.67 ± 1.03, Ag 1.83 ± 0.71 and Cd 0.73 ± 0.14 with significant difference (p < 0.001) between periods. Ni, Pb and Cd had values above FAO/WHO recommended limits. Estimated daily intake values were below the reference oral doses and the target hazard quotient was <1 for each metal examined while hazard index for all metals was also <1. The target carcinogenic risk value for Ni was 3.4 × 10^-3. Based on the evaluations, the study concluded that consumers of crabs from the study area had minimal/moderate metal toxicity exposures of no significant health concern but recommended continuous monitoring to detect anomalies.