HEAVY METALS CONCENTRATIONS IN CHOCOLATE, CANDIES AND TOMATO PUREE

ABSTRACT

This study was initiated as a follow-up information on some impounded products tomato puree (Concentrations of some heavy metals such as (Cadmium, Cobalt, Copper, Ferric, Mercury, Manganese, Nickel, Lead and Zinc) were determined in tomato paste were related to different foreign companies (11companies) which considerable as more commercial marks in Nigerian markets and more causal use by Nigerian people Atomic absorption assay was using for this purpose. Also, bacterial and fungal analyses were done for these studied samples in order to give a full assessment of the some imported tomato paste from different near countries. The concentrations values of Cadmium ,Cobalt ,Ferric ,Mercury ,Manganese ,Nickel and Lead were exceed the acceptable values of Iraqi standard and World health organization (WHO) for all studies samples , while the concentrations of Copper and Zinc were do not exceed acceptable values for them

CHAPTER ONE

INTRODUCTION

1.1         BACKGROUND

Metals are widely found in our environment, they and other elements can be naturally present in food or can enter as a result of human activities such as industrial and agricultural processes. The metals or particular concern in relation to harmful effects on health are mercury, lead, cadmium, tin and arsenic (Voegborlo and El-Methnani, 1999). Canned food is subjected to heavy metal contamination during the canning process. The ingestion of food is an obvious means of exposure to metals, not only because many metals are natural components of food stuffs, but also environmental contamination and contamination during processing (Voegborlo and El-Methnani, 1999). The toxicity of heavy metals has two main aspects: the fact those they no known metabolic function. But when present in the body they disrupt normal cellular processes, leading to toxicity in a number of organs, also the potential, particular of the so-called heavy metals mercury and lead, to accumulate in biological tissues, a process known as bioaccumulation. This occurs because the metal, once taken up into the body, is stored in particular organs. For example the liver or the kidney, and is excreted at a slow rate, compared with its uptake. This process of bioaccumulation of metals occurs in all animals including food animals such as fish and cattle as well as humans.It is therefore necessary to control the levels of these toxic metals in foodstuffs in order to protect human health. (Authority of Ireland –food safety- 2009). Toxicological and environmental studies have prompted interest in the determination of toxic elements in food .Mercury, cadmium and lead can be tolerated only at extremely low levels and at certain concentration they are exceptionally toxic to humans (Voegborlo and El-Methnani, 1999). The mechanism of metal toxicity: metallic toxicant in canned tomato paste through exposure or ingestion may find their way into the body, at such, may act through one or more of these possible mechanisms: inhibition of enzymatic activities (Ademoroti,1994; Alka,2000), attack on cell membrane and receptor (Alka,2000), interference with metabolic cations and action on artery (Michael and Peter, 2003). In this study the objective was assessment the quality of some food products were imported to Iraqi markets and use by Iraqi people in their daily meals, the results which provide information on the content of nine heavy metals (Cd,Co,Cu,Fe,Hg,Mn,Ni,Pb and Zn )in canned tomato paste directed primarily for human consumption , and note if the concentrations of these metals with permissible values or not, in order to give a sight for the people to be careful ,and take care to choose the suitable food product in their daily meals ,

Taking into consideration that products passed through different industrial processes and are packaged to provide a means of protection, marketing or handling, and most of them have printed colour inks on the outer cover (Kim et al., 2008). Importantly, food products such as candies that are likely to be consumed frequently by small children are wrapped in colourful packages in order to induce them to purchase the products. Heavy metals, such as Pb, Cr, Ti, Zn and Cu can migrate from the printed surface to the food contact surface through four mechanisms: blocking, rubbing, peeling and diffusion (Bradley et al., 2005). Contamination of imported food products with heavy metals may cause a serious risk to human health because of the consumption of even small amount of metals can lead to considerable concentrations in human body. Metals that cannot be metabolized like cadmium, lead and mercury persist in the body and exert their toxic effects by combination with one or more reactive groups essential for normal physiological function and cellular disturbances or clinical manifestation may appear (Friberg and Elinder, 1988; Skerfving, 1988). The adverse toxic effects caused by lead (Subramanian, 1988), cadmium (Friberg et al., 1986), mercury (Manahan, 1989) and tin (Reilly, 1991) are widely recognized.

In spite of the hazard effects of heavy metals on public health, some of them are essential for normal physiological functions such as copper and zinc (Zaki, 1988; Hays, 1989). Also, copper sulphate exhibits clear reduction of cadmium residues in animal tissues (Ahmed et al., 1999), the dietary deficiencies of copper, zinc, calcium, iron, protein and an excess dietary fat cause an increase in the absorption and toxicity of lead (Goldfrank et al., 1990). Although there are standards set by the quality control bodies such as National Agency for Food and Drug Administration and Control (NAFDAC) and Standards Organization of Nigeria (SON) for permissible concentrations of these contaminants in imported products, the problem still exists because many Chinese manufacturers have two

or more versions of their products: one specifically designed to meet standards set by the import country, and a cheaper and poorer version for the native market (Medlin, 2004). Coupled with the fact that route of entry differs, therefore, monitoring of heavy metal content in these products is essential especially with their related health implications. The potential for exposure, though, is not completely understood due to the lack of data regarding heavy metal levels in various products and the extent of use within Nigerian communities. Canned tomatoes and candies, however, are of particular concern because of their potential for children consumption.

1.2         STATEMENT OF THE PROBLEMS

The metal contamination in food has raised public and scientific interest due to their dangerous effects on human health. This has led researchers all over the world to study the pollution with heavy metals in air, water, and foods to avoid their harmful effects and to determine their permissibility for human consumption Baysal (2012). Tomato is one of the most widely cultivated crops in the world. Tomatoes contribute to a healthy, well-balanced diet. They are rich in minerals, vitamins, essential amino acids, sugars and dietary fibres. Tomato contains much vitamin B and C, iron and phosphorus. Tomato fruits are consumed fresh in salads or cooked in sauces, soup and meat or fish dishes. They can be processed into purées, juices and ketchup. Canned and dried tomatoes are economically important processed products Naika S, Joep J, Goffau M, et al. (2005). Tomato sauce and similar products are widely used for coloring and taste enhancement of various food products. Apart from their taste properties they also have a high nutritive value due to the content of easily retainable sugars, vitamin C, carotenoids and mineral salts David I, Stefanut MN, Balcu I, et al.  (2008), in traditional way for preparing tomato paste, the tomatoes are washed and chopped. After a while they squeeze the tomatoes to drain water. Then pour it in a strainer to separate the juice from the pulp.

Also, essential elements are present in the industrial processes and agrotechnical operations, so disregarding their nutritive essence, their contents should be determined because they can often reach toxic level (Kim et al., 2008). Copper intoxication can be caused by its many chemical compounds which are components of fungicide used in agriculture and veterinary practice. Using vegetables and fruits grown on high copper soil (near smelters, industrial factories) is also a cause of copper intoxication. Zinc and iron used in the form of alloys in industry and in some inorganic fertilizer components, could lead to high concentration of these metals in soil and then in plants grown in the soils.

Canned foods offer a shortcut in meal preparation which is most favored by those who are stretched for time. Canned fish, milk, tomatoes products manufactured either locally or imported, are very popular in supermarkets and small grocery retail outlets.

1.3         JUSTIFICATION

According to Dahiya et al (2005), the future of any nation depends on the health, prosperity and progress of the forthcoming generation. Presently, in the era of industrialization, development and inter-boundry trades, one concern should be the health of the future generation. Children are the most vulnerable age group to any kind of contamination in the food chain (Arreola et al., 1996). Lollipop, chocolate, biscuits and milk candy are some of the favourite items of children and are often presented to them as token of love and affection from their parents, relatives and friends (Dahiya et al., 2005). Many brands of these kinds of child-consumed favourite items are available in the market at variable prices, among them are those imported from Peoples’s Republic of China which are sold at a low price. Most of the packaging is so poorly designed that the inner coatings do not maintain structural integrity, allowing ink component in the outer packages layer to migrate into the products (Kim et al., 2008). This could be a possible route of heavy metals into the children body system.

Also, it is a common phenomenon to list ingredients on the wrappers. The most common ingredients listed are sugar, liquid glucose, milk solids, cocoa solids, hydrogenated vegetable oil, vegetable fats, cocoa butter, wheat flour, edible starches, added flavor, yeast and flavor improvers, buffering agents and permitted stabilizer. Out of the listed ingredients, hydrogenated vegetable oil, vegetable fats, permitted emulsifier, buffering agent and permitted stabilizer may be the source of trace metal contamination (Dahiya et al., 2005).

In September, 2008, at least 12 countries had banned Chinese dairy products and these products were even recalled from shelves throughout Asia and in some African countries (CRS Report, 2008). Food products such as biscuits, chocolates and milk candies could be made from contaminated milk powder and children who consumed such food products could potentially exceed the tolerable daily intake (TDI) by more than threefold (European Food Safety Authority (EFSA), 2008). It is therefore necessary to monitor the level of heavy metals in these products especially its health risk implications.

In Nigeria, tomato paste, which constitutes a significant volume among canned vegetable products are mainly imported. The processing plants for the tomato paste are depending on their farmland, most of which are irrigated, for the supply of raw materials (Jones, 1987). The plants use fertilizer and agricultural chemicals for the production of raw materials. Hence, the need to determine the levels of essential and toxic heavy metals in canned tomato paste imported into the country become essential due to their beneficial or damaging effects. Moreover, it has becomes necessary to know about the concentration of essential and toxic heavy metals in canned tomato paste to ensure the quality of the product and to comply with quality and specification standards developed by the Codex Committee on Processed Fruits and Vegetable (CCPFV).

Increase of metal contamination in food and food products over the allowed limits (either concerning non essential or essential metals in surplus), may cause toxic effects to the consumers of the products. The gravity of toxic effects depends on the nature, quantity and chemical form of metals and synergetic or antagonistic effects of other chemical contaminants. Children are mostly exposed to the toxic metal effects through food and some of the favourite gifts. Metal genoxic effects are more often in the children because their organs grow faster, the metabolism is more intense and the cells are divided more quickly (Vitosevic et al., 2007).

Studies on the assessment and evaluation of safety of food products are mainly carried out in developed countries. Literature information on such studies in developing country like Nigeria where such “junks” are constantly circulated in the markets and consumed by families is scarce. Thus, this study is necessitated to identify and characterize imported candies and canned tomatoes paste from China into the country. This is because the safety of our food products supply is a shared responsibility, from the fork of the food producing industry, regulatory authorities, scientists and consumers. As part of this responsibility, this study was conceived to assess the potential risks posed by food ingredients (canned tomato paste) and candies imported from China.

1.4         HYPOTHESIS

The purpose of this study was to identify and determine the level of heavy metals in different imported canned tomato pastes and candies from China into the country, considering that these products are supplied to every market in the country. Therefore, the study is based on the following null hypotheses:

1.  metal concentrations of candies and canned tomato pastes purchased from different zones of the country do not differ, and their heavy metal levels are within acceptable or safe limits.
2. Candies and canned tomato paste of different types do not have equal metal concentrations

1.5         AIM AND OBJECTIVES

The aim of this study was to determine some heavy metals (Cu, Mn, Fe, Ni, Zn, Ti and Cr) which might be essential at low concentrations in some canned tomato paste (testi tomato paste and merysa concentrates de tomato paste) chocolates and candies (lollipop with pencil, milk candy, royal glucose and biscuits) imported from China and to provide data that may be used as the basis for preventive measures. This was set to be achieved through the following objectives:

1. To determine the metal contents of canned tomato pastes, lollipop, biscuits, milk candy and chocolates from China sold in Nigeria major markets.
2. To compare the levels of the metals in canned tomato paste, lollipop, biscuits, milk candy and chocolates with international standards.
3. To determine the risk associated with the consumption of these products.

1.6         LIMITATIONS OF THE STUDY

The major limitation of the study was the availability of research materials. as there are very limited empirical study on the similar topic. The study was limited to these brands of canned tomato pastes and candies due to their availability in all the selected markets from the six geographical zones of the country. Finance was also a major limitation of the study as the researcher could not reach out to more respondent,

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