Determination of the Levels of Trace Elements in Some Canned Foods
Chapter One
Aim and Objectives of this Research
The primary aim of this research is to determine the concentration levels of trace elements in some canned foods to achieve the following objectives concerning canned sardine fish and canned tomato paste samples:
- To assess the health significance associated with the consumption of a particular trace element in these foods;
- To indicate the possible presence of potentially toxic substances in these samples;
- To show whether or not the restrictions placed on the use of toxic substances as additives in the production and/or processing of these foods are being met in practice;
- To assess whether there is a need to introduce new legislation or to revise existing ones as they affect these foods;
- To indicate the level of safety of these canned
- To achieve these objectives, the samples would be analysed using X-ray fluorescence Spectrometry (XRF). It is available at the Centre for Energy Research and Training/Ahmadu Bello University (CERT/ABU), Zaria.
Chapter Two:
LITERATURE REVIEW
Growing concern about the quality of food has brought about numerous investigations on the presence of essential and toxic trace elements in different foodstuffs [Milacic and Kralj (2003)].
Food has been identified as the primary means of exposure of the general population to chemicals, apart from occupational and incidental means as well as gaseous pollutants. For instance, methyl mercury contaminated fish consumed in Japan was identified to be the causative agent in the 1965 Minamata and Niigata diseases; mercury treated wheat grains consumed in Iraq in 1972/73 was also said to have affected 6,500 people and to be responsible for at least 459 hospital deaths; the Itai-Itai disease with bone damage in Japan was attributed to the consumption of cadmium contaminated rice; amongst several unreported cases [Lindsay (1981), Hamilton (1979), CAOBISCO (1996)]. These discoveries have made it imperative to obtain data on the elemental constituents of the foods we eat and their health implications.
The exposure to trace elements in foods may come from:
- concentration of environmental levels of trace elements by many organisms
- contamination of food by processes such as canning [Pickford (1981)] as well as some activities of
Food is a constant source of toxic trace elements which accumulate in different parts of the human body and cause damage in many of its basic systems (renal, cardiovascular, gastrointestinal, endocrine, nervous, etc). While mercury, lead, and cadmium are considered to be the most dangerous metals even at low concentrations, other elements such as copper, nickel, chromium, zinc, iron and manganese, although considered essential, can also produce toxic effects and cause metabolic anomalies when their intake is excessively elevated [Tuzen (2003), Cid et al (2001), Pickford (1981), CAOBISCO (1996)].
The dietary intake of an element from food consumption is dependent on the concentration of the element in the food and the amount of the food consumed [Ikem and Egiebor (2005)]. Thus, the need for continuous assessment of the levels of all the trace elements in foods, whether toxic or not, is quite essential since some of the beneficial ones among them could have some adverse health effects at concentrations higher than the normal level required by the body especially if they are such that are not readily excreted.
Potential Health Effects of some Trace Elements
Adequate physiological functions of humans require adequate intakes of some essential trace elements. However, humans get exposed to harmful non-essential elements, apart from occupational and incidental means, through consumption of fresh and processed foods [Ikem and Egiebor (2005), Yang (2005), Ryan et al (2001)]. Such toxic elements which are usually persistent and not easily biodegradable [USFDA (2008)] may be biologically incorporated into items of food, trapped on external surfaces, or added as a result of manufacturing, or preparing foods for consumption [Hamilton (1979)].
A number of trace elements have received attention as both environmental contaminants, and potential health and toxicologically hazardous materials. The toxicological hazards may be due to their relative uptake and accumulation and toxicity to humans [Ryan et al (2001), CAOBISCO (1996)].
Chapter Three:
MATERIALS AND METHODS
Materials
Samples
The samples analysed in this study were two (2) brands of canned sardine fish (Titus™ and Princesse ™) and four (4) brands of canned tomato paste (De Rica ™, La Bianca ™ Pomo ™ and Tomato-Fun ™).
The sample sizes were determined using the student t–test at 95% level of confidence.
Canned sardine fish
Eleven samples each of the two brands (making a total of twenty – two) were purchased and coded as follows (for identification purposes) in addition to their Batch Numbers and Best Before Dates as shown in Tables 3.1 and 3.2 below:
Chapter Four:
RESULTS AND DISCUSSION
The results obtained for the analyses of the samples using the X–Ray Fluorescence technique (XRF) as well as the observations on them are as outlined below.
Canned Sardine Fish Samples
Tables 4.1 and 4.2 show the concentrations in mg/kg (ppm) of each of the elements detected in the two brands of the canned sardine fish samples (TitusTM and PrincesseTM) analysed.
Chapter Five:
CONCLUSION AND RECOMMENDATION
Summary
The presence of trace elements, mostly trace metals in foods have become a matter of serious concern in view of their now known potential health effects even at sub- ppm level for some of them like mercury, lead, cadmium, chromium and arsenic. Even those considered essential for healthy living often impact on health negatively at high concentrations.
The level of concentrations of trace elements in samples of two brands canned sardine fish (Titus and Princesse) and four brands of tomato pastes (De Rica, La Bianca, Pomo and Tomato-Fun) was determined with X–Ray Fluorescence spectrometer. The results obtained indicated generally very high values for all the elements detected in all the samples analysed.
There is therefore the need for continuous monitoring of all foods, especially when canned (since canned foods can add more elements and/or increase their levels in the foods) in order to assess their level of safety.
Conclusion
The samples obtained and analysed all indicated the presence of varying types of trace elements. In all, seven elements were detected in the two brands of the sardine fish samples (bromine, copper, iron, nobium, nickel, zinc and zirconium) and nine in the four brands of the tomato paste samples (arsenic, bromine, chromium, copper, iron, lead, titanium, vanadium and zirconium).
In the sardine fish samples analysed, only copper, iron, nickel and zinc can be said to be essential for human health. However at deficient or elevated levels they can be harmful. Their levels of concentration in this study were seen to be high. Bromine, nobium and zirconium are not known to have any beneficial effect. In fact, they are harmful and can be very dangerous to humans.
In the tomato paste samples analysed, copper and iron detected in them are the only elements that benefit humans; arsenic, lead and chromium which are elements of serious health concern were observed to be present in very large amounts far above any national or international recommendation; bromine, titanium vanadium and zirconium which have various forms of potential health implications were also detected in the tomato paste samples analysed.
In this study, the generally very hazardous elements were found in the tomato pastes and as such require caution in their consumption.
Recommendations
Following the outcome of this study, the recommendations below are being put forward for possible action:
- All canned sardine fish and tomato pastes should be thoroughly screened to determine if any toxic elements and even those safe at low concentrations but potentially toxic at high concentrations are present and at what level of concentration. This action is recommended to be applied to all canned foods, especially the imported
- All producers/importers of these products should be mandated to make available verifiable analytical reports on every batch of these products to relevant regulatory agencies who shall in turn carry out follow up tests before authorising their release for public consumption.
- Further work is suggested to be carried out on the specific form or state of the elements since it is not all the oxidation states or forms of some of the elements that are
- Consumption of these products should be monitored so that the level of intake of the essential nutritive elements among them remain within the beneficial level in the body and the effects of the toxic ones get equally
- Thorough screening of especially all the tomato pastes imported into or produced in Nigeria should be given high priority as this study has shown that lead, arsenic and chromium were detected in only the tomato paste
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