In the wake of South Africa’s peanut butter scare, food safety expert Professor Lucia Anelich sheds light on aflatoxin risks. House of Natural Butters’ products, found with excessive aflatoxins, prompted widespread recalls of peanut butter.
There is much reputable information on the internet and this article is designed to bring aflatoxins into some perspective for consumers in particular. It is important, however, that consumers stop consuming these products and return them as per instructions.
First things first, what are aflatoxins? Well, aflatoxins are a group of toxins that are produced by several fungi, but most importantly, Aspergillus flavus and Aspergillus parasiticus. These fungi are found naturally in the environment as is the case with most other fungi.
They can therefore, be present on different crops, such as cottonseed, maize, rice, some spices, cocoa beans, tree nuts and peanuts whilst growing in the field. The aflatoxins are then produced by the fungi mainly when these commodities are stored incorrectly (warm and humid conditions) after harvesting.
In some cases, the toxins are produced in the commodities whilst still in the field. Even figs have been contaminated with aflatoxins.
Are there different types of aflatoxins?
The four major naturally produced aflatoxins are called B1, B2, G1 and G2. A. flavus produces B1 and B2 whilst A. parasiticus produces B1, B2, G1 and G2. Of all four types of aflatoxins, B1 is the most toxic.
Another one is M1 which is similar to B1 (and so not considered an additional type) and humans are exposed to M1 practically exclusively through milk and milk products, including breast milk.
There are some harmful effects of consuming aflatoxins. These toxins are potent liver carcinogens, capable of causing cancer in all animal species studied, including humans. However, an important point to make is that one of the most important concepts when dealing with any toxin is dosage.
It was Paracelsus in 1538 who said, “All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison.” This is often condensed to “The dose makes the poison”. It means that a substance can produce the harmful effect linked to its toxic properties only if it reaches a system within the body that is vulnerable to that toxin, in a high enough concentration.
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Who is exposed to aflatoxins?
It is estimated that around 4.5 billion of the world’s population (more than half of the world’s current population), mainly in developing countries, is exposed to aflatoxins.
Because aflatoxins are found so abundantly across many staple foods in developing countries, one could be exposed to low levels over a long period of time.
In fact, this continuous exposure at low levels is known as chronic exposure and can be the cause of liver cancer many years later, estimated at around 20 years later.
Is there a “safe” level for aflatoxins?
There is currently no zero level possible for aflatoxins in susceptible commodities, although that would be the ideal. It is for this reason that there are regulatory limits in place in most countries for such commodities, with the express aim to limit exposure to these toxins through food and animal feed.
South Africa follows the limits proposed in the relevant Codex Alimentarius Commission standard (a joint Food and Agriculture Organisation/World Health Organisation body).
South African regulatory limits as per the relevant regulation R 1145, are as follows:
- A maximum of 15 micrograms/kg (parts per billion or ppb) of total aflatoxins in peanuts intended for further processing (for example, to make peanut butter from);
- A maximum of 10 micrograms/kg (ppb) of total aflatoxins, of which a maximum of 5 micrograms/kg of aflatoxin B1 for all foodstuffs, ready for human consumption
- A maximum of 0.05 micrograms/litre (ppb) of aflatoxin M1 in milk.
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What about other countries?
The European Union (EU) has stricter maximum levels for aflatoxins in several different commodities which can be viewed here.
What types of illnesses are caused?
There are two categories into which effects fall when ingesting food contaminated with aflatoxins. The first one is known as acute aflatoxicosis (poisoning through aflatoxins), where extremely high levels of the toxin are ingested.
Such cases are very rare, but when they do occur, liver failure results and people die. Three notable incidents have occurred, namely, India in 1974, Kenya in 1981, and again Kenya in 2004 – all from consuming excessively contaminated maize. In such cases, death can occur within days of ingesting the product.
What is evident from these poisonings and the research work done on these incidents, is that those people had very little else to consume and so they were consuming not only highly contaminated food, but large amounts of it as well i.e. their portion sizes and frequency of eating that contaminated food were very high.
Important: To date, there have not been any reported acute aflatoxicoses related to consuming peanuts or peanut-based products.
The second category of aflatoxicosis is known as chronic exposure. This is where one is exposed to lower levels of aflatoxin over a longer period of time. The effects here are varied, with liver cancer being the most prominent, possible outcome. Other effects include suppression of the immune system and growth stunting in children. Aflatoxin can cross the placental barrier, where the foetus is affected and then exposure after birth would exacerbate the stunting.
What is considered when determining the effects of aflatoxin exposure?
There are many factors that play an important role in understanding potential effects and all of these need to be considered when determining possible outcomes.
Factors that play a role are:
- Age of individual (children are more seriously affected).
- Health status of the individual (any underlying conditions, such as hepatitis B which is the leading cause of liver cancer worldwide).
- Weight of individual.
- Nutritional status of individual.
- Variety in the diet of the individual (if one eats mainly maize or peanuts with very little variety in the diet, then one is more susceptible to aflatoxin effects).
- Frequency of consumption (how many times a day/week/month one consumes that food).
- Portion size (as levels of aflatoxin are presented as micrograms/kg of product (ppb), consuming a certain portion size will also determine how much aflatoxin one is consuming at a sitting).
- Period over which the contaminated food is ingested (days, weeks, months, years).
Furthermore, inherent genetic differences across the human population may also result in different reactions or differences in the severity of reactions. Evaluating all these factors forms an important part of conducting a risk assessment, to quantify the magnitude of exposure and the subsequent probability of a harmful effect to affected people.
- Professor Lucia Anelich has a PhD in microbiology and is currently the managing director of her own food safety training and consulting business, Anelich Consulting. The views and opinions expressed in this article are those of the author and do not necessarily reflect the views or positions of Food For Mzansi.
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