AFLATOXIN M1 CONTAMINATION OF RAW COW MILK, MILK PRODUCTS AND DIETARY EXPOSURE

ABSTRACT
Globally, the occurrence of Aflatoxin M1 in milk and milk products has been reported in many countries and therefore a thorny issue especially for developing countries. Despite the health effects of exposure to Aflatoxin M1 such as acute liver damage, cirrhosis of the liver and tumor induction, studies on occurrence and dietary exposure is generally lacking in Ghana. This study therefore sought to determine the incidence and dietary exposure to Aflatoxin M1 in three selected suburbs in the Greater Accra Region of Ghana.

Thirty (30) samples of raw cow‘s milk, 30 samples of Burkina drink and 23 locally made cheese (wagashi) were randomly purchased from the three suburbs (Ashaiman, Madina, Nima) in the Greater Accra region and analysed for the presence of aflatoxin M1 (AFM1). Solid phase extraction was used for the extraction and clean-up of samples and subsequently analysed using a high-performance chromatography coupled with fluorescence detector and Pyridinium Bromide Perbromide (PBPB) as a post column derivatization agent for detection and quantification. Using a food frequency questionnaire to obtain food consumption estimates and mean body weights, a deterministic approach was used to calculate the estimated daily intake (EDI) of AFM1 through raw cow‘s milk, burkina drink and wagashi. Five of the thirty milk samples (16.67%) were positive with mean AFM1 levels of ±0.25 ug/l. Seven of the thirty Burkina samples (23.33%) showed presence of AFM1 with mean concentration of ±0.09 ug/l. Five of the cheese samples showed presence of AFM1 with mean concentration of ±0.04 ug/kg. The concentrations of AFM1 were lower in the locally made cheese than in the raw cow‘s milk and Burkina drink. All the individual results for each product was above the EU limit of 0.05 ug/kg. For EDI, the results obtained showed that infants recorded the highest mean AFM1 across the three food types and therefore the age group exposed to significant risk. AFM1 intake through wagashi was relatively lower across all age groups compared to burkina drink and raw cow‘s milk.


CHAPTER 1
INTRODUCTION
1.1 Background
Milk is sometimes referred to as nature‘s single most complete food because milk and milk products have been used by man since primitive times O‘Connor, (1994) and most importantly because nearly all the constituents of milk are very essential for life. It has an extremely high nutritional quality, performing numerous vital functions, including growth, supply of energy, reproduction, maintenance and repairs, and appetite satisfaction (O‘Connor, 1994). Amongst human population, children and especially infants who require milk for proper development during growth, usually consume milk in high quantities. Notwithstanding the health benefits associated with milk, it could also be a potential source of natural food contaminants that may cause ailment and pose adverse health effects. One group of such contaminants is mycotoxins.

Contamination of milk and milk products with AFM1 (a mycotoxin) has been known worldwide for close to twenty years. This phenomenon is therefore an important problem across the globe and particularly so for developing countries (Iqbal et al., 2015).

―Aflatoxins are naturally occurring mycotoxins produced mainly by moulds (Aspergillus flavus and Aspergillus parasiticus)‖ (Kim et al., 2000). Aflatoxin M1 (AFM1) a metabolite of Aflatoxin B1 (AFB1), has been found to be a major excretory product in the milk of lactating livestock and humans exposed to dietary AFB1. In livestock, this is mainly as result of feeding on contaminated food products.

The International Agency for Research on Cancer (IARC) until the year 2002 classified Aflatoxin M1 as class 2B carcinogen, which meant the toxin was a possible carcinogen to humans. It had been shown experimentally that AFM1 presents high hepatotoxic and mutagenic risk (FAO/WHO, 1999). The IARC however reviewed the classification of AFM1 from class 2B to group 1, meaning AFM1 is carcinogenic to humans after genotoxicity and carcinogenetic of AFM1 was observed in vivo, although lower than those of AFB1, and its cytotoxicity demonstrated (Caloni et al., 2006; IARC 2002). Aflatoxins are both acutely and chronically toxic for animals and humans and can produce adverse health effects including acute liver damage, liver cirrhosis and tumor induction (Simon et al., 1998). According to Egal et al. (2005), there are some evidence for associations with health problems such as Reye‘s syndrome, kwashiorkor, and acute hepatitis. Young children and infants have a higher risk of exposure to AFM1compared to adults within the human population. This is mainly so because infants and young children are known to consume relatively higher quantities. Evidence of AFM1 contamination of milk is well documented. The results of a survey conducted in Tehran, Iran, indicated that Aflatoxin M1 (AFM1) was found in 78% of commercial liquid milk, 33% of milk-based weaning foods analyzed. The levels were found to be higher than the maximum tolerance limit accepted by the European Union (Oveisi et al., 2007). A similar survey conducted in India by Rastogi et al. (2004), showed the occurrence of AFM1 in infant milk products and milk products. Of the samples analyzed, 87.3% were found to be contaminated with AFM1. The outcome of the study showed that infant milk products were much contaminated at higher levels relative to liquid milk.

It has also been reported that Aflatoxin M1 contamination has been found in milk and milk products in Portugal (Duarte et al., 2013), Serbia (Kos et al., 2014), South Africa (Dutton et al., 2012) and Syria (Ghanem and Orfi, 2009). There is also evidence of the occurrence of AFM1 in biological fluids of humans such as urine and breastmilk. Makun et al. (2016), detected AFM1 in breast milk of breastfeeding mothers. The results of the study showed that for human breastmilk, the incidence of AFM1 occurred at 77.5%. Also, out of 40 samples, 15 representing 37.5% were contaminated at levels that were above both EU and the Nigerian permitted level of 0.05µg/l.

The global occurrence of Aflatoxin M1 in foods has necessitated the need for a public health intervention to safeguard the health of consumers from the potential adverse health effects of this toxin. One of such interventions is the setting of allowable limits. Thus, the regulatory or governing goal is that the allowable limits implemented by countries as standards will not be exceeded.

The international regulations for the maximum limit for AFM1 in milk and dairy products vary among countries especially within the European Union and the United States of America (USA). ―According to the United States regulations, the AFM1 levels should not exceed 0.5 μg/kg. However, the Codex Alimentarius set 50 ng/kg as the regulatory limit and for infant milk and follow-on milk, no more than 0.025 µg/kg is allowed‖ (EC, 2006). Similarly, in Austria and Switzerland, the maximum level is only 10 pg/mL for infant food (FAO, 1997). Most studies conducted on milk and milk products across the globe have shown occurrence of AFM1 in dairy products and milk. (Iqbal et al., 2015). Monitoring via regular surveillance studies and analysis of commercially available milk on the market also continues to be one key measure of controlling or eliminating this toxin from human diet and thereby preventing the potential adverse health effects that are associated with it.


1.2 Problem Statement
Milk continues to be a nutritious food and a source of both macro and micronutrients for the development, growth and maintenance of good health. Generally, almost all age categories of the human population consume milk and milk products on a regular basis as part of their diet (Fallah et al., 2009). In Ghana, especially on the major streets, there is increase sale of raw cow milk product popularly called ―Burkina drink‖. At food vending joints where porridge (locally called ―koko‖) is sold, there is also increase patronage of another product made from raw cow milk, known as ―wagashi – which is a local cheese. In most peri-urban areas in Accra, the fresh/ raw cow milk is also sold and consumed or used in preparing foods.

AFM1 contamination of milk and milk products at the global level is well established and reported in many countries (WHO, 2010). Milk and dairy products contamination with aflatoxin M1 is therefore an important problem worldwide especially for developing countries. It is therefore hypothesized that fresh/ raw cow milk and milk products in Ghana are contaminated with AFM1 and therefore pose health risk to consumers. Despite the health effects of exposure to AFM1, studies on levels in milk and milk products are generally limited in Ghana. It is therefore imperative to assess the levels and dietary exposure to this human carcinogen. Kumi et al. (2015) reported significant levels of AFM1 in urine samples of children (6 to 2years) in three communities in Ashanti region. This study was unfortunately only limited to cereals and legumes fed to children. Studies on levels in milk and milk products are generally lacking. There is therefore an urgent need to determine the levels of AFM1 and estimate dietary exposure. The outcome will contribute significant information to risk management and policy making in Ghana.

1.3 Aims and Objectives

1.3.1 Aim
The main aim of this study is to determine the occurrence and levels of Aflatoxin M1 in commercially available fresh/ raw cow milk and milk products in Ghana and potential adverse effect of consuming these locally manufactured fresh milk and milk products.

1.3.2 Specific objectives 
To meet the main aim of the study, below specific objectives have been set out to be achieved;

To determine the Aflatoxin M1 contamination levels in selected locally produced fresh/ raw cow milk and milk products sold on the Ghanaian market.

To conduct a dietary exposure assessment for the locally produced fresh cow milk in the selected areas in Accra.

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Item Type: Ghanaian Postgraduate Material  |  Attribute: 87 pages  |  Chapters: 1-5
Format: MS Word  |  Price: GH50  |  Delivery: Within 30Mins.
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