Levels of Heavy Metals in Pasta Available in the Nigerian Market: Assessing the Health Implications
Objective of Study
- To determine the levels of Cd, Pb, Zn, Mn, Cu, Cr and Ni in locally produced and imported pasta in the Nigerian market.
- To determine the levels of Cd, Pb, Zn, Mn, Cu, Cr and Ni in the locally manufactured and imported pasta available in the Nigerian
- To compare the levels of these metals in the locally produced and imported
- To determine any correlation in the metal levels in each pasta
- To compare the extent of compliance to guideline values of these metals to some International
- To estimate the daily intake (DI) of these metals through pasta consumption for adults and
- To compare the DI values with accepted daily intakes stipulated by International Standard
- To estimate any associated health risk in the consumption of pasta by children and and adult.
It is quite disturbing that over 200, 000 Nigerians die from food poisoning every year . Recent media report in Nigeria indicates that these deaths are caused largely by foods contaminated through improper processing and preservation . Food poisoning being an illness caused by the consumption of food or water contaminated by toxic chemicals, bacteria, parasites, or viruses can be prevented if Nigerians take the necessary precautionary measures. A WHO report says 30 per cent of people living in industrialised countries may suffer from food-borne illnesses each year. In the United States, the Centres for Disease Control and Prevention estimates that food-borne diseases cause about 76 million illnesses, 325,000 hospitalisations, and 5,000 deaths each year
. This includes heavy metals poisoning in processed food. The annual cost of food-borne illnesses in the US alone is estimated to be between $7.7 billion and $23 billion .
Several countries are committed to ensuring food safety by conducting routine checks on the quality of processed food whether imported or home made. For instance, in Nigeria, examinations are conducted by NAFDAC (National Agency for Food and Drug Administration and Control) and SON (Standard Organisation of Nigeria [2, 3], in China, examinations are conducted by the National Food Quality Supervision and Inspection Centre and the National Quality Supervision and Testing Centre for Processed Food (Guangzhou) . Routine checks are done not only to ensure food safety but also to avoid food safety scandals in a given country. A number of Taiwanese instant noodle firms became embroiled in such food safety scandals when authorities launched examinations of 129 packets of seasoning oil and vegetable flavours of 67 instant noodles which revealed the presence of arsenic, lead and copper in them .
In India, the Uttar Pradesh Food Safety and Drug Administration prosecuted Nestle India as samples of their Maggi noodles was found to contain high levels of lead beyond the permissible level .
In Bangladesh, some brands of commercial noodles were investigated and found to contain varying concentrations of different heavy metals .
Studies have been carried out on the presence and levels of toxic metals in both packaged and unpackaged food substances. Heavy metals, in particular, have been repeatedly found to be present in some of these food sources in many parts of the world [18-25]. Elements such as Cd, Cr and Pb are considered carcinogenic, while Fe, Cu, Zn, Ni and Mn are considered as essential metals . However, if the concentrations of the later elements are higher than their permissible limits they may create toxic effects in humans . These heavy metals are said to be potential environmental contaminants with the capability of finding their way into the food we eat and causing human health problems. They are given special attention throughout the world due to their ubiquitous nature and toxic effects even at very low concentrations . Several cases of human disease, disorders, malfunction and malformation of organs due to metal toxicity have been reported . The major route for humans’ exposure to heavy metals is through the food pathway .
Pastas are among the most widely consumed “fast foods” in many homes within and outside Nigeria, yet there have been little information on the pastas produced in different parts of the world. However, heavy metals have been determined in some food produced from flour such as bread, cassava flour, etc as well as in the materials used in packaging instant noodles.
In Nigeria for instance, a study on Potassium Bromate and heavy metals content of some selected bread samples in Zaria Metropolis showed that the concentrations of Pb, Fe and Cd in the samples were above permissible limits while Cu and Zn were within permissible limits .
A survey of the heavy metals in some brands of instant noodles in Eke-Awka market, Anambra state confirmed the presence of Pb, Cd, Cr, Fe and Zn .
In another study where quality assessment of instant noodles sold in Nigerian markets was carried out; Pb, Cd and Cr were found to be in concentrations above permissible limits .
Also, a survey of metal profiles in some wheat based snacks from different kitchens in Akure, Nigeria showed that not all the heavy metals detected were within permissible levels .
Like essential mineral nutrients, toxic heavy metals also naturally occur in soils and water. Plants and animals can take up and concentrate heavy metals, which is why small amounts of these substances can often be found in our food supply. It’s common for even fresh whole foods like seafood, fruits and vegetables to contain trace amounts of heavy metal toxins .
But it’s important to remember that much of the heavy metal content in our modern food isn’t naturally-occurring, but instead, comes directly from modern agricultural practices, industrial production and storage processes of foods. Chemical fertilizers, pesticides, and improper handling of sewage are all known to cause heavy metal contamination of food supply .
Additionally, countless hundreds of industrially-processed food additives often add to the toxic metal content of modern foods, as do metals used in food production and packaging. Ultimately, it is safe to assume that the greater degree of processing a food undergoes, the greater the risk of heavy metal contamination . When viewed from this perspective, then, it should come as no surprise that pastas – a highly processed consumable product – is suspected to contain potentially unsafe level of metal toxins.
According to the International Union of Pure and Applied Chemistry or IUPAC, the term heavy metal may be a meaningless term because there is no standardized definition for a heavy metal . Some light metals or metalloids are toxic, while some high-density metals are not. For example, cadmium generally is considered a heavy metal, with an atomic number of 48 and specific gravity of 8.65, while gold typically is not toxic, even though it has an atomic number of 79 and specific gravity of 18.88. For a given metal, the toxicity varies widely depending on the allotrope or oxidation state of the metal. Hexavalent chromium is deadly; trivalent chromium is nutritionally significant in many organisms, including humans .
Heavy metals are also defined as metallic elements that have a relatively high density compared to water . With the assumption that heaviness and toxicity are inter-related, heavy metals also include metalloids, such as arsenic, that are able to induce toxicity at low level of exposure [34, 35]. Any metal (or metalloid) species may be considered a contaminant if it occurs where it is unwanted, or in a form or concentration that causes a detrimental human or environmental effect. Metals include lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), chromium (Cr), copper (Cu), selenium (Se), nickel (Ni), silver (Ag), and zinc (Zn). Other less common metallic contaminants include aluminium (Al), cesium (Cs), cobalt (Co), manganese (Mn), molybdenum (Mo), strontium (Sr), and uranium (U) .
Heavy metals are potential environmental contaminants with the capability of finding their way into the food we eat and causing human health problems. They are given special attention throughout the world due to their ubiquitous nature and toxic effects even at very low concentrations . Several cases of human disease, disorders, malfunction and malformation of organs due to metal toxicity have been reported .
In this study, two different analyses were carried out:
- Determination of the concentration of seven heavy metals inpasta
- Estimation of the dietary intake of pasta consumers and exposure to heavy metalsfrom pasta
Heavy Metal Analysis
Locally produced and imported pasta were collected from the 3 cities in Nigeria (Lagos, Abuja and Enugu) to reflect the kinds of pasta commonly retailed to consumers in November 2014. The identified products were categorized into three (3): noodles, macaroni and spaghetti. The manufacturer details of each product including brand name, batch numbers, production and expiry dates were obtained from the packaging of each product are listed in Table 1.
Results and Discussion
Results of Metal Analysis
Table 2: % Recovery for Pb, Zn, Ni, Mn, Cu, Cd and Cr in Pasta samples
Heavy metals are considered particularly dangerous to human health because of the danger of bioaccumulation. In this study, the concentration of Pb was above permissible in all the samples, while the Cd and Cr levels were above permissible limits in some samples. The concentrations of Pb, Cd and Cr are more in the imported pasta samples than in the locally manufactured pasta samplesThere was no significant difference between locally manufactured noodles, spaghetti and macaroni but, there was significant difference between imported noodles, spaghetti and macaroni. The estimated dietary intakes of metals from the consumption of these pastas were less than the provisional tolerable weekly intake. From the estimated target hazard values, no lifelong health concerns of metals were associated with the consumption of these pastas. The results of this study indicated that the imported pastas contained higher metal loads compared with Nigerian pastas.
- The Punch, August 24, 2012. Saving Nigerians from Food Poisoning: EditorialBoard
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