Evaluation of heavy metals in different fish samples from different water sources in Odisha: Animal and human health risk assessment

Introduction

Fish contains all necessary amino acids and in comparison to red meat, has low fat content. Fish also contains Omega-3 fatty acids EPA (Eicosapentaenoic acid) & DHA (Docosahexaenoic acid). In eastern India, traditionally fish is a regular part of diet of pregnant women believed to be helpful in cerebellar and brain growth of the foetus. (Basak et al., 2020) [1] . Effluents released into different water body cause unintended changes of the ecosystem causing imbalance in environment and affect people directly or indirectly. The accumulation of metals in food and their impact on people is a global concern. In various circumstances metal pollution of water bodies pose serious concerns. Aquatic creatures are the first to suffer. Heavy metals enter into the food chain and harm other animals depending on bioaccumulation and bio magnifications. Ample amount of fatty acids, proteins, carbs, vitamins, minerals and essential amino acids are found in fish. Fish is one of the major sea food, so accumulated heavy metals in fish is transferred to humans. (Raja et al., 2009) [10] . A diverse group of fishes known as freshwater fish inhabit water bodies where salinity is less than 1.05%. The muscle protein of fish is highly valuable because it has essential amino acids lysine and threonine which are crucial for protein synthesis and other functions in humans. Major non-protein nitrogenous compounds found are proline, glutamine, glycine, alanine, and arginine and taurine. Tuarine is important for bile salts. Taurine alone or with LC-PUFA reduce the risk of coronary heart diseases (James, 2013) [5] .

To manage women's various health conditions, fish oil is used such as to relief in painful periods and breast pain. (Phang et al., 2005) [14] Contaminated by various drugs/chemicals freshwater ecosystem, fish accumulate harmful chemicals which ultimately harm the other animals and people who consume them.

Materials and Methods

Selection of fish species

Commonly consumable and highly demanded fish species were selected for this current study work. Labeo rohita (Rohu), Cirrhinus cirrhosus (Mrigal), Tuna (Thunnini) fish, Bhetki (Lates calcarifer) and Pomfret (Pampus argenteus) fish were selected for further study work. Labeorohita (Rohu) and Cirrhinus cirrhosus (Mrigal) collected from Mahanadi River. Bhetki and Pomfret fish collected from local market of Puri. Tuna and Rohu fish collected from local market of Chilika. Both production and consumption of Rohu, Mrigal and Tuna as regular fish meals on different occasions or ceremonies is more than other finfish and shellfish Therefore, these species consumed the maximum population of Odisha.

Markets selection for sampling

Commonly consumed fish species were purchased from the local fish market of Chilika, Puri and Mundali villages. In Odisha, there is a brackish water lagoon known as Chilika Lake that spans the districts of Puri, Khurda, and Ganjam. Different fish species were collected from different water sources, i.e., Chikika Lake, Puri Sea and Mahanadi River. Puri sea contains salty water, Mahanadi River contain fresh water.

Sample digestion

 One gm of sample was taken for a determination of different metals concentration.  One gm of dried powder sample taken into a volumetric flask into which 70% of 6 ml Nitrous oxide (HNO3) and 30% of 4 ml Hydrogen peroxide (H2O2) were added. Then volumetric flask was kept on the hot plate for digestion.  Hot plate temperature was adjusted to 210 °C for the digestion of the fish sample. The sample was heated until the color changed from brownish yellow into transparent yellow to transparent. The sample was heated for complete digestion.  After that sample was taken from the hot plate and kept to be cooled Measured 25 ml of ultra-pure water by using ameasuring cylinder.  Then the sample was poured into another empty volumetric flask and then 25 ml of ultra-pure water was added. Ultra-pure water makes a solution diluted. Whatmann filter paper no. 41 was used for the filtration of the solution.  Then it was analyzed for the presence of heavy metals by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) available at the central instrumentation Facility, OUAT.

The following metals were estimated from the collected tissue samples (Liver, Muscle):

Results

In the current study, the metal accumulation pattern exhibited the following order: Fe > Zn > Cu > Cr > Hg.

The location-wise difference in metals accumulation in fish liver samples: Among 3 locations metals accumulation was higher in Mahanadi River and lower in Chilika Lake. and Chilika places. Along with that there was also significant difference observed in metals concentration (Cr, Cu, Fe, Zn, Hg). P value observed was < 0.01.

Discussion

The present study aimed to determine the metals Conc. (Cr, Cu, Fe, Zn, Hg) in different fish species. Liver and muscle tissue samples were collected and determine the metals conc. in tissue samples. For the study work, fish species were collected from 3 locations, i.e., Mahanadi River, Puri and Chilika Lake. Fish were purchased from the local fish market. Chilka Fish was more-safer than Puri sea fish and Mahanadi river fish. More metals concentration was accumulated in Mahanadi river fish. More metals accumulated in mrigal fish than other fish species.

In the current study highest metals conc. found in the liver as compared to the muscle which was supported by the liver is a key organ for detoxification, and it is where many harmful substances acquired from the environment are cleaned up (Fernandes et al., 2008) [3] . The distribution of metals in fish organs, such as the liver, gills, muscle, and gonads, varies, leading to variances in metal accumulations in these organs (Chi et al., 2007) [2] . The investigated metals were found in muscle at the lowest amounts, but the liver found to be the principal tissue for accumulating heavy metals. The levels of heavy metals in the muscle were safe for human consumption (Jaric et al., 2011) [4] . Metals have varying affinities for fish tissue and have different absorption, deposition, and excretion rates, there are variances in the bioaccumulation of metals in fish bodies (Jezierska et al., 2006) [6] .

In the liver, metallothionein binds toxic metals such as Cu and Zn. According toreports, the detoxification, redistribution, and storage of heavy metals are all crucial functions of the fish liver (Weber et al., 2013) [16] .

In the present study, more metals accumulated in Cirrhinus spp than in Labeo rohita which was similar to the findings of (Rauf et al., 2009) [11] and also more accumulation in the liver sample as compared to muscle.

In the present study, less metals conc. found in fish muscle samples which were similar to the findings of (Kargin et al., 1991) [7] muscle tissue is the most crucial component of the fish used in the experiment since it is the part that humans most frequently ingest and is not thought to be an active site for the buildup of metal.

In the present investigation, the accumulation of metals was in the following order: Fe > Zn > Cu > Cr > Hg which was similar to the findings of (Parida et al., 2017) [13] . Also similar to the findings of (Velusamy et al., 2014) [15] important data on the levels of heavy metals in fish from Mumbai Harbor and international markets also found a higher level of Fe present in the fish sample as compared to other metals. A similar order of accumulation of metals was observed in (Prasath et al., 2008) [9] but in his study, there was a significantly high conc. of iron and zinc found.

In the present study, Hg Conc. found in the range between 0.13-0.20 mg/l and it is found to be lower than the USEPA (2001). These range slightly lower than those (Velusamy et al., 2014) [15] . Due to industrial waste discharges, mercury (Hg), a very hazardous element, severely pollutes the environment. Fish ingest Hg by feeding, which can be predicted by factors such as fish size, food, ecological factors and water quality factors. Zinc was the second most abundant metal found in these studies. Zinc Conc.in the present investigation was in the range between 12.66-19.30 in the liver sample which was below the permissible limit of FAO (1983), WHO (1989). Table 12 indicates that the present study level of Zn was lesser than fish samples of Mumbai Harbor (Velusamy et al., 2014) [15] but more than the Calicut India Fish samples (Sankar et al., 2006) [12] & Mumbai, India fish samples (Mishra et al., 2007) [8] .

In the current study, Cu Conc. found in the range between 14.52-17.28 mg/l which found below the permissible level set by (WHO 1989/FAO 1983). Table 12 indicates that the present study level of Cu was somewhat more than in other locations.

In the present study, Cr Conc. found in the range between 0.58-0.78 mg/l which found below the permissible level set by (FAO 1983) and was slightly higher than that (Velusamy et al., 2014, Mishra et al., 2007) [15,8] .

Conclusion

In this particular study, our focus was on assessing the concentrations of various metals, including iron, zinc, mercury, copper and chromium, in both the muscle and liver tissue of five distinct fish species. "P" value was observed <0.01 there was a significant difference observed in the accumulation of metals with respect to muscle and liver samples of fish collected from different locations i.e., Mahanadi River, Puri Sea, Chilika Lake.

In the present investigation, the accumulation of metals followed a distinct order: iron (Fe) > zinc (Zn) > copper (Cu) > chromium (Cr) > mercury (Hg). This order highlights the varying concentrations of these metals within the samples analyzed. Throughout all the results, a considerably higher amount of metals was observed in the liver samples compared to the muscle tissue. Chilka fish was more safer than Puri sea fish and Mahanadi river fish. More metals concentration was accumulated in Mahanadi river fish. More metals accumulated in mrigal fish than other fish species.

In our comprehensive analysis, it was determined that all measured metal concentrations in the fish samples remained below the maximum permissible limits established by reputable regulatory bodies such as the Food and Agriculture Organization (FAO), World Health Organization (WHO), United States Food and Drug Administration (USFDA) and United States Environmental Protection Agency (USEPA). During the investigation higher conc. of Iron was observed in all 3locations and a lower level of mercury conc. was observed. We conclude that the edible part of fish is safe for human consumption in a different region that was selected for the study.

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