This review discusses several research studies that employed comet assay to evaluate the environmental impact of genotoxins in aquatic environments. It focuses on in vivo and in situ studies of aquatic animals. New chemicals are being added each year to the existing burden of toxic substances in the environment. Excessive agricultural and industrial activities adversely affect biodiversity, threatening the survival of species in a particular habitat, as well as posing disease risks to humans. Some of the chemicals, e.g., pesticides and heavy metals, may be genotoxic to the sentinel species and/or to non-target species, causing deleterious effects in somatic or germ cells. Comet assay is a quick, sensitive, and low-cost technique for detecting DNA strand breakage. However, the comet assay has much more to offer than being an assay for testing DNA strand breaks in animal organs. The use of repair enzymes increases the range of DNA lesions that can be detected with the assay. Comparing data from studies that employed different approaches, such as empirical scoring or comet tail lengths, comet assay is one of the challenging techniques to be utilized in environmental studies. The relative amount of DNA in the comet tail indicates DNA break intensity. The assay has been modified to detect various base alterations by including the digestion of nucleoids with a lesion-specific endonuclease. The determination of DNA damage in these indicator species using the comet test would thus offer information on the genotoxic potential of their habitat at an early stage. This would enable intervention techniques to prevent or mitigate adverse health impacts in sentinel animals and humans.

Metallic trace elements toxicity has been associated with a wide range of morphological abnormalities in fish, both in natural aquatic ecosystems and controlled environments. The bioaccumulation of metallic trace elements can have devastating effects on several aspects of fish health, encompassing physiological, reproductive, behavioural, and developmental functions. Considering the significant risks posed by metallic trace elements-induced toxicity to fish populations, this review aims to investigate the deleterious effects of prevalent metallic trace elements toxicants, such as mercury (Hg), cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As), and copper (Cu), on the neurological, reproductive, embryonic, and tissue systems of fish. Employing diverse search engines and relevant keywords, an extensive review of in vitro and in vivo studies pertaining to metallic trace elements toxicity and its adverse consequences on fish and their organs was conducted. The findings indicate that Cd was the most prevalent metallic trace elements in aquatic environments, exerting the most severe impacts on various fish organs and systems, followed by Cu and Pb. Moreover, it was observed that different metals exhibited varying degrees and types of effects on fish. Given the profound adverse effects of metallic trace elements contamination in water, immediate measures need to be taken to mitigate water pollution stemming from the discharge of waste containing metallic trace elements from agricultural, industrial, and domestic water usage. This study also compares the most common methods for treating metallic trace elements contamination in water.

Heavy metal accumulation in freshwater ecosystem has become one of the major aquatic environmental concerns for freshwater flora and fauna due to their higher stability and bioaccumulation as well as bio-magnification properties. Furthermore, passing through the food web, these heavy metals affect human populations ultimately. This study assessed the heavy metal accumulation in Cirrhinus mrigala in spring, autumn, and winter at different locations (I, II, and III) of Panjnad headwork. Furthermore, the human health risk assessment for the consumption of C. mrigala from the sampling locations was also carried out. Fish were collected from upper (I), middle (II), and lower (III) stream of Panjnad on a monthly basis. The current study evaluated the accumulation of Aluminum (Al), Arsenic (As), Barium (Ba), and Lead (Pb) in various fish organs (liver, kidney, gills, fins, skin, muscles and bones) and assessed their potential hazard to human health through health risk assessment indicators. The results demonstrated a significant difference (p < 0.05) in heavy metal accumulation in different fish organs, seasons, and locations. The accumulation of Al, As, Ba, and Pb were considerably higher in liver and kidney as compared to the other body organs and followed a trend of liver > kidney > gills > fins > skin > bones > muscle and the overall mean concentrations of metals in different body tissues of C. mrigala were in the order of Al > As > Ba > Pb. The results also concluded that C. mrigala caught from the Panjnad headwork is not safe for human consumption due to higher values of TTHQ_Ing (3.76), THQ_Ing for Ba (3.27) and CR_Ing for As (6.4742).

Aquatic toxicology, as a result of industrial and agrieqcultural effluences, has become a global concern impacting not only the well-being of aquatic organisms but human health as well. The current study evaluated the impact of four toxic trace elements (TTEs) Cadmium (Cd), copper (Cu), lead (Pb), and nickel (Ni) in three organs (liver, gills, and muscles) of five fish species viz, Rita rita, Sperata sarwari, Wallago attu, Mastacembelus armatus, and Cirrhinus mrigala collected from right and left banks of Punjnad headworks during winter, spring, and summer. We investigated the accumulation (mg/kg) of these TTEs in fish in addition to the human health risk assessment. The obtained results showed that W. attu accumulated significantly more TTEs (p < 0.00) as compared to other fish. Among seasons, summer had significantly more (p < 0.00) accumulation of TTEs than other seasons. Lead (Pb) accumulation was highest across TTEs in fish liver as compared to gills and muscles. The right bank showed higher accumulation (p < 0.00) of all TTEs in all fish species compared to the left bank. The human health risk assessment showed that Cd and Pb had higher exposure levels than Cu and Ni. Furthermore, the THQ was in the order of Cd > Pb > Ni > Cu. All fish species had THQ 1 for Cd and Pb and TTHQ > 1 for all fish. MPI index showed moderate to high levels of TTE contamination in all fish species. The study concluded that the right bank has higher metal accumulation than the left bank. However, fish consumption from both study sites was unsafe for human consumption. Further studies are required to evaluate the contamination of other trace elements in the aquatic ecosystem of the current site. This study will be useful for policymakers and the water department to take necessary counteractions to reduce the impact of TTEs at the study site.