SAFETY ASSESSMENT OF EDIBLE SEAFOOD FOR HEAVY METAL CONTAMINATION WITH REFERENCE TO METAL BINDING PROTEIN
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Date
2019
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Fisheries College and Research Institute, Thoothukudi, Tamil Nadu Dr. J. Jayalalithaa Fisheries University
Abstract
The distribution of heavy metals, lithium (Li), chromium (Cr), cobalt (Co), nickel (Ni), iron (Fe), copper(Cu), zinc(Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead(Pb) in different organs such as gills, bone, liver and muscle of nine finfish and the muscle/ mantle, gill and digestive gland of three crustaceans and three cephalopods were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as per AOAC (2015). The liver was the main organ of accumulation for Cu, Zn, As, Cd, Hg; bone for Cr, Co, Pb; gills for Cu & Muscle for As and Hg. In the crustaceans and cephalopods, digestive gland was the main organ of accumulation. Cd was the metal of concern in shellfish as the digestive gland of cuttlefish contained Cd as high as 70 μg/g. The heavy metal concentration in the edible portion of fish (348 pools) and shellfish (198 pools) were analyzed every month for a period of 12 months in four locations of Thoothukudi District viz. Tharuvaikulam, Therespuram, Thoothukudi Fishing Harbour and Punnakayal. The order of mean concentration of heavy metals in fish and shellfish recorded in these regions was: Zn >As >Cu >Se >Ni >Cr >Hg >Pb>Co >Cd >Mo. The high concentration of heavy metals in most of the fish and shellfish were recorded during pre-monsoon season. Significant difference (p<0.05) in the heavy metal concentration between the four locations and among different species of fish and cephalopods analysed was recorded. Risk assessment was carried out among the fish consumers of Therespuram fishing village. The Target Hazard Quotient was below 1 for fish and shellfish. The Total THQ was above 1 for rock crab indicating non-carcinogenic risk upon its consumption.The carcinogenic risk of As and Pb was within the range of 10-5 to 10-7 indicating that there is no carcinogenic risk upon consumption of fish and shellfish from this region. The concentration of heavy metals in the internal organs viz. gills, reproductive/ nidamental gland , digestive gland and mantle of Indian squid, Uroteuthis duvaceli, stored in ice was studied. There was an increase in the concentration of all heavy
metals in the mantle upon storage, which indicated leaching of heavy metals from the internal organs to the mantle.The heavy metal and MT concentration between the muscle and gills of grouper and tuna showed significant (p<0.05) difference. The correlation between the heavy metal and MT concentration clearly indicated that MT can serve as biomarker for Cu, Zn, Se, Mo, Cd and Hg. The MT gene expression of the clams, Meretrix meretrix, was studied subjecting the clams to various treatments T1- 25, T2- 500 & T3- 1000 ppb of cadmium chloride on days 1, 3 & 5. The cadmium concentration in the gills of the clams increased with the dose and time. MT gene expression was noticed in T2 on day 3 where the Cd concentration in the gills of clam was 2.94μg/g.