The word “Aflatoxin” is an uncommon, unheard of scientific term for the vast majority in Sri Lanka. However it is not an uncommon word to anyone who has studied biology for Advanced Levels. It is basically a toxic substance which is produced by a fungus.
Aflatoxin came into the limelight recently in Sri Lanka when it was discovered that certain imported cooking oils contained the toxin and was being investigated by the Customs and the Sri Lanka Standards Institute. The Sri Lanka Customs had seized two bowsers with 55,000 litres of oil deemed to be contaminated with Aflatoxin. Meanwhile things took an unpleasant turn when the Head of the Sri Lanka Standards Institute (SLSI) Dr. Siddhika G. Senaratne, in a controversial interview, revealed that SLSI was aware of many other products which contained aflatoxin which is already being consumed by the Sri Lankan public. This comment has caused widespread uproar leaving many doubtful on which products are safe to consume and which products need to be boycotted.
In this backdrop, it is pertinent to look at what exactly Aflatoxin is and what its implications are if consumed by humans.
What is “Aflatoxin”?
It is a toxic substance produced by a group of fungi that are found on agricultural crops such as maize (corn), peanuts, cottonseed, and tree nuts The main fungi that produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus, which are abundant in warm and humid regions of the world.
How are humans exposed to aflatoxin? 
There are several ways that aflatoxin can be ingested by humans, mainly it is by ingesting and consuming plant products (nuts, peanuts) contaminated by aflatoxin or by eating meat and dairy products of animals who were fed with contaminated feed such as poorest quality contaminated grain. Agricultural workers may be exposed to dust of crops which are contaminated.
Aspergillus species in particular, grow on nuts and seeds and crops stored under unfavorable conditions such as warm, moist humid conditions or on dead and decaying vegetation.v
Several types of aflatoxin (14 or more) occur in nature, but four – aflatoxins B1, B2, G1 and G2 are particularly dangerous to humans and animals as they have been found in all major food crops; but most human exposure comes from contaminated nuts, grains and their derived products. Pre-harvest contamination with aflatoxins is mainly limited to maize, cottonseed, peanuts and tree nuts. Post-harvest contamination can be found in a variety of other crops such as coffee, rice and spices.
What are the harmful effects of aflatoxin?
Effects of aflatoxin are many, and depends on the duration and the amount of ingestion. Aflatoxin ingestion in small amounts may not cause serious symptoms acutely, however long term exposure brings about serious consequences.
Acute ingestion of aflatoxin in large doses such as 1mg per kilogramme of body weight can cause the condition “aflatoxicosis” which is mainly caused by damage to the liver causing acute liver failure. Symptoms of acute liver failure could be jaundice (yellowish discoloration of skin, eyes and mucous membranes), lethargy, nausea, bleeding, edema (swelling) and can even lead to death.
Aflatoxins are potent carcinogens (cancer causing substances) and linked to development of liver cancer and cancers in the kidneys, gall bladder and other types of cancer as well. It is particularly harmful for people with hepatitis infections, this precipitates development of liver cancer faster.
Aflatoxin can also cause birth defects such as stunting of growth in children, however stunting of growth has not been proven to have a direct relationship with aflatoxin exposure yet because it is multifactorial, with association with poor nutrition, low socio-economic status and infectious diseases.
It is also known to cause immunosuppression or cause low immunity, which leads to poor resistance to disease like tuberculosis and HIV.
Aflatoxins not only affect humans but animals too. No living species are immune to aflatoxin. It can cause liver damage in chickens, cattle and pigs and cause poor weight gain, poor milk and egg production as well.
Aflatoxin can be transmitted through breast milk, thus once congested by a feeding mother, this toxin can be transmitted through breast milk to the baby. Also, as mentioned before it can be present in dairy products from animals that have been fed with grains stored in poor conditions.
Aflatoxin in cooking oil
How is aflatoxin present in oil? It is not only present in coconut oil. Most cooking oil used in Sri Lanka is coconut oil, some vegetable oils such as sunflower seed oil and oils derived from nuts and grains such as soya oil, sesame and corn oil are also available in the market. If these oils are produced from nuts, grains and produce stored in poor conditions where aspergillus species are free to grow, aflatoxin is sure to be a component in the oils produced from these.
A research on “Occurrence of aflatoxins in edible vegetable oils in Sri Lanka” done by Nuwan B. Karunarathna, Chandima J. Fernando, D.M.S. Munasinghe and Ruchika Fernando published in 2019 delves into the matter of aflatoxin in edible oil in Sri Lanka and the results are not favourable.
They have found that nearly 38% of the coconut oil samples were contaminated with aflatoxins. Coconut oil, palm oil, sunflower oil, sesame oil, olive oil, soya bean oil and corn oil were tested. Coconut oil included locally produced branded products and unbranded products, whereas the other vegetable oils included only the branded products most of which were imported. Total aflatoxin level in samples was determined using Enzyme-Linked Immunosorbent Assay (ELISA), and the positive samples were further analysed using High-Performance Liquid Chromatography.
In this study they have used 32 coconut oil samples, which included five brands and seven unbranded products, had total aflatoxin contamination and aflatoxin B1 contamination. Out of these 12 samples, 10 and 11 samples exceeded the European Union’s maximum permissible levels applicable for total aflatoxins respectively. All positive coconut oil samples were regular coconut oils, which had been extracted from copra (dried coconut kernel). Aflatoxin contamination in other vegetable oil types and virgin coconut oil was below the limit of detection of the ELISA.
All positive coconut oil samples contained aflatoxins B1, B2 and G1, with aflatoxin B1 being the predominant type, but aflatoxin G2 was not detected in any of the samples. They conclude by stating that high levels of aflatoxin contamination in coconut oil may have resulted from improper practices during the copra production that facilitate toxigenic fungal growth on copra.
Another study “A survey of aflatoxin contamination of coconut products in Sri Lanka; incidence, origins and recommendations” published in 1983 by U. Samarajeewa and S. N. Arseculeratne has found that approximately 50% contained medium-high levels of aflatoxin B1. They further analyse that the aflatoxin levels in the products from 25 mills which were in continuous production during the survey period, were classifiable as ‘regularly high’, ‘occasionally high: regularly medium-low’ and ‘low or nil’. These patterns were correlated with rainfall techniques for curing of copra, conditions of storage, prolonged storage of copra, admixture of high quality copra with substandard kernels for oil extraction and the lack of quality control measures.
What needs to be done?
Aflatoxin exposure is not a matter to be taken lightly. As Sri Lankan consumers we put our faith on the authorities such as the Ministry of Health, Sri Lanka Standards Institute, Consumer Protection Bureau, and Sri Lanka Customs, to ensure that harmful products are kept well away from the market and consumers.
Standards and testing methods need to be regularised and benchmarked according to the highest standards and random testing of products available in the market should be done to detect unhealthy substances. Furthermore, local manufacturers need to be mindful in using raw material such as copra of good quality, and ensure proper storage of copra and adopt safe production procedures, while the Coconut Development Authority and Coconut Research Institute should implement proper protocols in production, testing before distribution into the market. Furthermore, strict guidelines and laws to be implemented in importation of food products.
These measures may be academically correct, but in practice will it be upheld and continued by Sri Lankan authorities? Can we trust the authorities to have the competence and integrity to do so is the million-dollar question? We as consumers watchfully await to see what measures will be taken to safeguard us. Only time will tell.
(The writer is a medical officer currently attached to a government hospital. His experience spans across the medical profession as a medical practitioner, and across the pharmaceutical and surgical equipment industry. He also possesses an MBA and a Diploma in Economics. Having represented his university rugby team in international tournaments, he also has a special interest in sports medicine)