1.Lead as a Toxicant and PoisonLead has long been studied as a toxicantbecause of its high potential to cause various detrimental health effects.Chronic lead toxicity is quite common and can lead to irreversible healthafflictions relating to the renal system, central nervous system, and hepaticsystem among others. Lead acts as an enzyme inhibitor by binding to proteinsincluding enzymes. Organic lead compounds which are highly toxic are taken upeasily by the human body. Chronic lead poisoning can cause anaemia, extremefatigue, and when it gets accumulated in high quantities, can cause damage tovarious organs of the body.
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1.2.Lead contamination in fishWhile the most studied ways of leadcontamination are via paints, contaminated soil and drinking water, lead infood; specifically from lean meats and fishes is being increasingly lookedinto. Toxins released into water bodies are taken up by fishes via their feedas well as through their gills.
Lead, a common toxicant is mainly found in fishmuscles, gills and the liver. Due to bioaccumulation and biomagnifications, thelead is not degraded and passes on from the contaminated fish to other animalsthat consume it, including humans. 2.REVIEW OF LITERATURE§ In2005, William G. Brumbaugh and Christopher Schmitt studied and compared theconcentrations of Cadmium, Lead and Zinc in fish from mining influenced watersof Northeastern Oklahoma. Despite mining having ceased in this region more than30 years ago, the heavy metal wastes remain widely distributed. Liver, bloodand carcass samples from common carp, bass and catfish were analysed usingInductively coupled plasma mass spectroscopy (ICP-MS).
Common carp was found tohave the highest amount of lead. (Ref.) § From2011-2012, Elin Boalt, et al carried out a study on the presence of lead,mercury and cadmium in Baltic herring and perch from the Bothnian sea. Thesamples tested were dorsal muscle layer, liver and carcass homogenate.
Lead wasreported most often in the carcass homogenate and liver. (Ref.) § RohaslineyHashim et al studied the levels of lead, cadmium and nickel in fish collectedfrom the Kelatan river in 2014. The dorsal muscle tissue from 13 fish specieswas the analyte and the study was carried out using a graphite furnace atomicabsorption spectrometer. Omnivorous fish were found to have high levels ofcadmium and nickel while carnivorous fish had the highest concentration oflead. The species O. Hassetti and T.
Maculates had lead concentrations thatexceeded FAO Malaysian Food Act and WHO guidelines. (Ref.) § ShovanMNH et al, in the June, 2017; conducted a study to determine the levels ofheavy metals in the various organs of 3 commonly consumed fishes in Bangladesh– Catla, Pangus and Rohita usingAtomic Absorption spectrophotometry.
The gill of the Pangus fish was found tohave the highest concentration of lead (~48.3 ppm) that had far exceeded thelimits of WHO. (Ref.) § Theconcentration of heavy metals in farm sediments, feed and selected heavy metalsin various tissues of farmed Pangasiushypothalamus in Bangladesh werestudied by Das et al in July, 2017. The concentration of lead, cadmium, nickeland mercury were below WHO recommended limits but their concentration in thegills, kidney and liver of the fish were high above the tolerable level andhence the fish are unfit for human consumption. (Ref.) 3.
AIM AND OBJECTIVES3.1.AimTo determine the concentration of lead(Pb) in locally consumed fish species, Lutjanusgibbus and if they are fit for human consumption. 3.
2.Objectives§ To standardise a spectrophotometric method for thedetermination of trace amounts of lead in the homogenized carcass of Lutjanus gibbus§ Tocompare UV spectophotometry and Atomic Absorption Spectophotometry as methods fordetermining trace amounts of lead in fish.§ To estimate whether the sample is suitable for food orfeed based on World Health Organization – Maximum Level standard. 4.
MATERIALS AND METHODS4.1.Sample collection and PreparationLutjanus gibbuswas obtained from a roadside fisherwoman in Anna Nagar West who is frequentedby the residents of the place. The particular species was chosen because it isamong the commonly solf species of edible fish in the market. The fish was keptin the deep freezer until it was to be used for the experiment. For chemicalanalysis, homogenization was done using sodium phosphate buffer and the extractfiltered.
4.2.Preparation of standard Lead SolutionsA 100 mL stock solution of lead was preparedby dissolving 160 mg of lead acetate in double distilled water. The solutionwas standardized with EDTA using methyl blue as indicator to determine theconcentration of lead in it.
A series of standard solutions ranging from 25-150?gof lead were prepared. 4.3.UV-spectroscopy AnalysisTo the standardized lead solutionsranging in concentration from 25-150 ?g, 1.
5 mL of 1.95 X10 -4 M dithizone solution was added. This was followed by adding 1mL of 4 X 10 -3 M HCl and 4mL of 0.3 M CTAB (Cetyltrimethylammonium bromide). The mixture was made upto 10mL withdouble distilled water. The absorbance was measured at 500nm against a suitablereagent blank. The absorbance values of standard lead solutions were plotted toproduce a calibration graph.
The absorbance value of the sample was alsodetermined by UV spectroscopy. 4.4.
Atomic AbsorptionSpectroscopyAsimilarly obtained and treated sample was given for Atomic AbsorptionSpectroscopy analysis and results obtained by absorbance at 216.9nm.DISCUSSION:The lead concentration in the sample wasassessed by Atomic Absorption Spectroscopy (AAS).
The obtained value of 1.46ppm is less than the maximum permissible values set by the WHO of 2 ppm. Hencethe fish is suitable for consumption.
But, if more fish of the same species isconsumed, there is a risk of the lead concentration crossing the permissiblelimit, and thus possibly being harmful to the consumer, also, as lead has theability to bioaccumulate and biomagnify, if this fish species were to beconsumed by other predatory fish, it could further increase the leadconcentration in the fishes eventually consumed by humans. Initial testing was carried out using aUV/Spectrophotometer at 500nm. But the resultant absorbance was much higherthan the WHO standard limit of 2ppm and did not fall within the calibrationgraph obtained. Youngsters are more vulnerable to thedeleterious effects of trace amounts of lead and can suffer from permanentadverse health defects, mostly affecting the brain and nervous systemdevelopment. Lead can cause long-term health impairment in adults, such as highrisk of blood pressure fluctuations, and damage to kidneys. Exposure of highlevels of lead to pregnant women can cause stillbirth, low baby weight,premature birth etc. 7.FUTURE PERSPECTIVEThe concentration of lead in variousfish species could be studied and compiled.
This would give an idea as to theoverall lead intake of an average person in the locality who consumes fish fromthe same source. 8.SUMMARYLocally obtainedLutjanusgibbus was spectrophotometrically analysed for presence andconcentration of lead; both by an UV-Vis Spectrophotometer (Lead-dithizonesystem in a HCl medium) and an atomic absorption spectrophotometer.
The obtainedconcentration of 1.46ppm while lesser than the WHO maximum limit of 2ppm, stillposes a threat to the health of consumers as lead has the ability tobioaccumulate and biomagnify.