Scholarly Journal of Agricultural Science Vol. 3(6), pp. 210-213, June, 2013
Available online at http:// www.scholarly-journals.com/SJAS
ISSN 2276-7118 © 2013 Scholarly-Journals
Full Length Research Paper
Level of heavy metals in fresh and canned foods
consumed in North Central Nigeria
*Yakubu Ali Dallatu
1
, Stephen Eyije Abechi
1
, Hamza Abba
1
, Usman Shehu Mohammed
2
and
Eneyi Comfort Ona
1
1
Department of Chemistry, Ahmadu Bello University, Zaria-Nigeria
2
Department of Agricultural Engineering, Ahmadu Bello University, Zaria-Nigeria
Accepted 20 May, 2013
Heavy metals level in some selected fresh foods and their canned products were investigated in this
work. Samples were collected, digested by standard method and the metal level determined using
Atomic Absorption Spectrophotometer (AAS). The results showed that nickel (Ni) level was generally
low (0.0003 to 0.0044 mg/kg) in all foods investigated. There was no significance difference in the
levels of cadmium (Cd), lead (Pb), copper (Cu) and nickel (Ni) in fresh and canned foods. However,
there was a striking difference in the levels of zinc in the fresh and canned foods. Zinc (Zn) level was
found to be generally high, ranging from 0.0526 to 1.5472 mg/kg in canned food and 0.17841 to
6.41113 in the fresh food samples. It was also observed that the Zn concentration in the fresh food
samples were about five times the concentration found in the canned food products. Food
contamination may therefore, not necessarily be associated with the canning materials. It may
however, be linked to the source of the products and other environmental factors. The detected levels
of Ni and Cu did not exceed the toxicological reference values established by World Health
Organization (WHO). However, Pb and Cd levels are alarming and calls for concern. Pb values ranges
from 0.0951 to 0.2852 mg/kg in fresh food samples and ranged between 0.01051 and 0.2852 mg/kg in
canned food products while Cd varied from 0.0073 to 0.1919 mg/kg and 0.0091 to 0. 297mg/Kg in fresh
food samples and canned products respectively.
Key words: Food contamination, food safety, environmental pollution, toxicology, heavy metal poisoning.
INTRODUCTION
Foods contain a wide range of metallic elements such as
sodium (Na), potassium (K), iron (Fe), (Ca) calcium, (Cu)
copper and (Zn) zinc. Many of these metals are essential
in living organisms. Nevertheless, a considerable number
of them are harmful to plants, animals and man even at
low concentration. This is particularly true of heavy
metals such as mercury (Hg), arsenic (As), copper,
cadmium (Cd) and lead (Pb). Toxicological and
environmental experts have shown concern for the
increasing cases of food contamination with these heavy
metals over the years as reported in several literatures
(Ray, 1994; Oehlenschlager, 2002; Damek-Poprawa et
al., 2003; Yargholi et al., 2008).
Canned fish is widely consumed in many parts of the
*Corresponding author. E-mail: abeshus@yahoo.com.
world because of its low saturated fat and omega fatty
acids that support good health (Ikem and Egiebor, 2005).
Fish are constantly exposed to chemicals in polluted and
contaminated waters. The effects of these heavy metals
on human health have also been reported (Munoz-Olivas
and Camara, 2001). Canned foods such as sardines,
geisha, and tomato paste are packed in tin or steel cans,
an air-tight container for distribution, storage or
preservation. High levels of metals may be found in
canned foods due to corrosion and leaching of the metals
from unlacquered cans, or from tin foils used in
packaging. These canned containers have a high
potential of releasing metals into the foods.
The most frequently used form of packaging for canned
fishery products is tinplate, fabricated into two and three
pieces of cans of a wide variety of shapes and sizes.
Tinplate consists of a base plate of low-carbon mild steel,
onto each surface of which is electrolytically deposited a