Features
Are we geared to handle aflatoxin problem meaningfully?
By Emeritus Professor
Upali Samarajeewa
(smrjee@gmail.com)
The media is full of information about the dangers of aflatoxins, increasing fear in the minds of public. Exposure to extremely small doses of aflatoxins of the order of micrograms per kilogram for long periods leads to liver cancer in humans and animals. Aflatoxins can also cause deaths within a few days if people are exposed to extremely high doses of it. In the world, there has been only one such recorded incident due to toxicity; 105 people died after consuming aflatoxin contaminated maize, during a famine in a neighbouring country. The toxic dose was around 20 mg per kilogram. That was in 1975.
In addressing a sensitive issue such as toxicity of human foods, the background scientific information needs to be understood in its correct perspectives to discuss and explore benefits of science to mankind. Aflatoxins are present in most foods in minute quantities. Unfortunately, none of the common food processing and preparation methods including heat processing or cooking could remove the aflatoxins significantly. In case of edible oils, aflatoxins could be removed industrially, only by chemical (alkali) refining. The treatment removes 98% aflatoxins in oils, bringing down aflatoxin concentrations in edible oils to levels safe for consumption. Other methods of ‘refining’ cannot remove aflatoxins. There is a patented process in Sri Lanka to remove aflatoxins in coconut oil using solar radiation. It needs to be scaled up for industrial use.
Humans do not live in an ideal world. We survive in a world of toxins, whether it is aflatoxin, other mycotoxins (mould toxins), heavy metals, like cadmium, mercury, lead or arsenic, or histamine in tuna fish, which causes allergic reactions, familiar to some of us. The list is much longer. We have learned to consume manioc containing cyanide by boiling in open pots to remove toxicity. Manioc is the staple diet in some of the African countries, but they live with it. Sri Lankans have learned to use goraka as a means of checking histamine producing bacteria in tuna fish. Panic should be avoided when it comes to understanding and handling the problems associated with foods.
Science has developed mechanisms to understand the amount of toxins that could be metabolized by the human body safely. Based on this information, risk level for each of the toxic entities in foods is worked out. The risk level is finally established at a concentration a few 1000 times less than concentrations experimentally established to be safe to humans. This simply means world possess regulatory systems, and dependable accredited testing systems, to make food consumption safe, avoiding naturally occurring undesirable constituents. It applies to aflatoxins as well. The volume of a food consumed by a human is also considered in deciding acceptable or tolerable levels, expressed based on per kilogram body weight of the consumer. Weight of the human body and the concentrations of deleterious entities that could be consumed without harmful effects are combined in establishing no-risk levels. Human health is primary in the efforts of sound science to make us live longer. That is food safety.
Ever increasing human populations against available lands and other resources to produce foods require new mechanisms to ensure food security. This is where strict application of ‘good practices’ in agriculture, food processing, and hygiene contributes to the well-being of humans through safe foods. There is the need for striking the best balance between protection of human health and possible application of good practices in food production to enable humans leade healthy lives without becoming a burden to the public health systems.
The food regulations meant to trike this balance continue to change with increasing scientific knowledge of human health as well as fast developing food processing technology. In the developed countries, food regulations are revised frequently to strike the above balance beneficially for humans. The same cannot be said of most developing countries. Sri Lanka is no exception. However, there are ample opportunities for countries, without adequate resources, to develop their own regulations adopting scientifically designed international “Codex” food standards, without reinventing the wheel.
“Codex” stands are developed by the Codex Alimentarius Commission, which is a joint committee of the FAO and WHO.
Taking the current global thinking and Sri Lanka’s needs into consideration, the table for aflatoxin regulatory limits was computed with the field experience of the author on food safety issues in more than 25 countries. It was made available to the health authorities in Sri Lanka a few months ago and Institutions interested in standards a week ago. It addresses the levels of acceptance or tolerance (ML = meaning maximum limit that could be tolerated in a food) for aflatoxins in common foods and feeds in Sri Lanka. The proposal also considered the test results generated in local accredited laboratories.
It focuses on the direction to be followed by Sri Lanka to address aflatoxicity problem. The responsible administrators and policy makers may use it. The scientific reasoning to keep the balance between health and food processing is summarised as notes in the table against each recommendation.
This information would be useful to the public, and those who are interested in understanding regulations in relation to presence of aflatoxins in foods in Sri Lanka. The proposed regulations would not contradict any of the globally used regulations in food trade.
Establishing standards is one thing. Applying it through testing only is the proof of the pudding. The interpretation of the generated test results is even more vital. The writer has tested more than 1,000 samples of foods including large number of coconut oil samples for aflatoxins in Sri Lanka and the US, working at the bench, and interpreting results for internationally recognised publications. The aflatoxins tend to adhere to laboratory glassware, and give a positive reaction for the next sample tested unless special cleaning techniques are used. This adherence can happen with any storage surface including container and bowser surfaces. The surfaces of bulk storage systems are never cleaned to get rid of the aflatoxins. Cleaning to remove storage tanks is practically impossible.
The interpretation of test results should be done with deep knowledge of background information. In interpreting test results for field samples, we need to be mindful that local coconut oil contains small concentrations (of the order of 5 -15 parts per billion) of aflatoxins and the imported oil (100 – 300 parts per billion, if what we hear in the press is correct). Skills of the scientist must go far beyond analyst, and the digits generated by instruments through the testing step. Interpretation of results is not a job for the layman. The testing requires demonstrated competency of analysts through continuous practice. Therefore, we need to resort to a laboratory accredited for the purpose. Gazetting a laboratory as public analyst or use of laboratories which holds accreditation for other tests, but not for aflatoxins, particularly oils, are not the best scientific approaches. Let us be mindful that we are discussing handling of human health through assessing an invisible toxin.
I sincerely believe that the decision makers take the above aspects into consideration in data interpretation responsibly, without leaving it to the newsmakers.