Lead as a Toxicant and Poison
has long been studied as a toxicant due to its high potential of causing
various detrimental health effects. Chronic lead toxicity is quite common and
can lead to irreversible health afflictions relating to the renal system,
Central nervous system, and hepatic system among others. Lead acts as an enzyme
inhibitor by binding to proteins including enzymes. Organic lead compounds
which are highly toxic are taken up easily by the human body. Chronic lead
poisoning can cause anaemia, extreme fatigue, and when it gets accumulated in
high quantities, can cause damage to various organs of the body.
Lead contamination in fish
the most studied ways of lead contamination are via paints, contaminated soil
and drinking water, lead in food; specifically from lean meats and fishes is
being increasingly looked into. Toxins released into water bodies are taken up
by fishes via their feed as well as through their gills. Lead, a common
toxicant is mainly found in fish muscles, gills and the liver. Due to bioaccumulation
and biomagnifications, the lead is not degraded and passes on from the
contaminated fish to other animals that consume it, including humans.
REVIEW OF LITERATURE
In 2005, William G. Brumbaugh and Christopher Schmitt studied and compared the
concentrations of Cadmium, Lead and Zinc in fish from mining influenced waters
of Northeastern Oklahoma. Despite mining having ceased in this region more than
30 years ago, the heavy metal wastes remain widely distributed. Liver, blood
and carcass samples from common carp, bass and catfish were analysed using
Inductively coupled plasma mass spectroscopy (ICP-MS). Common carp was found to
have the highest amount of lead.
From 2011-2012, 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. The
samples tested were dorsal muscle layer, liver and carcass homogenate. Lead was
reported most often in the carcass homogenate and liver.
Rohasliney Hashim et al studied the levels of lead, cadmium and nickel in fish
collected from the Kelatan river in 2014. The dorsal muscle tissue from 13 fish
species was the analyte and the study was carried out using a graphite furnace
atomic absorption spectrometer. Omnivorous fish were found to have high levels
of cadmium and nickel while carnivorous fish had the highest concentration of
lead. The species O. Hassetti and T. Maculates had lead concentrations that
exceeded FAO Malaysian Food Act and WHO guidelines.
Shovan MNH et al, in the June, 2017; conducted a study to determine the levels
of heavy metals in the various organs of 3 commonly consumed fishes in
Bangladesh – Catla, Pangus and Rohita
using Atomic Absorption spectrophotometry. The gill of the Pangus fish was
found to have the highest concentration of lead (~48.3 ppm) that had far
exceeded the limits of WHO.
The concentration of heavy metals in farm sediments, feed and selected heavy
metals in various tissues of farmed Pangasius
hypothalamus in Bangladesh were
studied by Pritika Rani Das et al in July, 2017. The concentration of lead,
cadmium, nickel and mercury were below WHO recommended limits but their
concentration in the gills, kidney and liver of the fish were high above the
tolerable level and hence the fish are unfit for human consumption.
AIM AND OBJECTIVES
determine the concentration of lead (Pb) in locally consumed biological
products (fish) and if they are fit for human consumption.
3.2.1. To standardise a spectrophotometric method for
the determination of trace amounts of lead.
3.2.2. To determine and compare the lead concentration
in fish carcass homogenate and fish liver.
3.2.3. To compare UV spectophotometry and Atomic
Absorption Spectophotometry as methods for the same.
3.2.3. To estimate whether the samples are suitable
for food or feed based on World Health Organization – Maximum Level standard.
MATERIALS AND METHODS
Sample collection, Storage and Preparation
of fish species) was obtained from a roadside fisherwoman in Anna Nagar West
who is frequented by the residents of the place. The particular species was
chosen because ____________. The fish was kept in the deep freezer until it was
to be used for the experiment. For chemical analysis, homogenization was done
using sodium phosphate buffer and the extract filtered.
Preparation of standard Lead Solutions
100 mL stock solution of lead was prepared by dissolving 160 mg of lead acetate
in double distilled water. The solution was standardized with EDTA using methyl
blue as indicator to determine the concentration of lead in it. A series of
standard solutions ranging from 25-150 ?g of lead were prepared.