- Farmers’/distributors'/sellers’ awareness campaigns, good agri. practices, surveillance & monitoring programmes recommended
A multi-sectoral approach is needed in order to reduce the level of contaminants in food and towards this end, it is recommended for countrywide awareness campaigns to be carried out to educate farmers, distributors and sellers on the adverse effects of such, and for farmers to be instructed to follow good agricultural practices and for surveillance programmes to be conducted to monitor contaminants and adulterants in food items.
These recommendations were made in a research article: “A baseline survey on food safety hazards in commonly consumed food items in Sri Lanka” which was authored by L. Gamlath, T. Siriwardana and B.H. Sudasinghe (trio attached to the Health Ministry's Directorate of Environmental Health, Occupational Health and Food Safety) and published in the Journal of the National Science Foundation of Sri Lanka's 49th Volume's Second Issue in September, 2021.
Food safety hazards
A food safety hazard, per the Codex Alimentarius Commission's “(2018). Procedural manual, 26th Edition”, can be defined as a biological, chemical or physical agent in food or the condition of food, with the potential to cause an adverse health effect. Food safety hazards are factors that the food safety practices seek to protect against, contain and eliminate from foods. Food safety has become an important public health concern and many governments have put in place measures to manage the risks arising from food safety hazards. A thorough understanding about the possible presence of these hazards is the first essential step in their control.
Food safety hazards can be introduced to foods during primary production due to the unsafe use of inputs and during food processing due to contamination, adulteration and the use of permitted food additives exceeding the recommended levels. The Codex Alimentarius Commission's “(2003). Codex codes of practice for general principles of food hygiene: CAC/ RCP 1-1969” defines a contaminant as ‘any biological or chemical agent, foreign matter, or other substances not intentionally added to food which may compromise food safety or suitability’. The Codex Alimentarius Commission's “(2015). Codex general standard for contaminants and toxins in food and feed, CODEX STAN 193-1995” definition of a contaminant implicitly includes naturally occurring toxicants including toxic metabolites of certain microfungi (mycotoxins) that are not intentionally added to food and feed. According to J. Spink's “The current state of food fraud prevention: Overview and requirements to address 'how to start?' and 'how much is enough?'”, while contaminants are not intentionally added food safety hazards, food fraud is an economically motivated concept that generally involves intentional actions taken to deceive consumers and which compromises the authenticity, safety, quality or reliability of food. As a subcategory of food fraud, the adulteration of food is the fraudulent substitution or addition of undeclared or unapproved substances to food products to increase their apparent value or to reduce the cost of their production for economic gain. J. Spink, B. Bedard, J. Keogh, D.C. Moyer, J. Scimeca and A. Vasan's “International survey of food fraud and related terminology: Preliminary results and discussion” defines an adulterant as ‘any substance intentionally added to food, which is not present in such food as a result of production’. Intentionally added substances, not only unpermitted, but permitted substances (food additives), also pose health risks if they do not adhere to the specified limits for use. Even though greater emphasis is on controlling food safety hazards during food processing, it is equally important to strive to control pesticide residues, residues of veterinary drugs, and other feed related additives that are the main food safety hazards resulting from primary production due to serious health hazards associated with their high intake into the body.
Unsafe chemicals found in food in SL
A public concern exists in Sri Lanka over food safety hazards originating from primary production, contaminants, adulterants and the unsafe use of chemicals in commonly consumed food items due to reported and foreseeable health risks. Among others, contaminants such as heavy metals in salt, mercury in fish, aflatoxins in chillie powder, peanut and coconut oil, and the microbial quality of food products are given higher attention.
Pesticide residues are a reason for public fear related to food safety arising from the primary production of food crops. Over the past decade, there is an increased concern over the use of pesticides worldwide. Pesticide residues in food, as deposits of active pesticide ingredients, their metabolites or breakdown products, have potential detrimental effects on human health. In Sri Lanka, the authorities are vigilant on pesticide residues in vegetables, fruits and green leaves and the Department of Agriculture has issued maximum residue limits (MRLs) for commonly used pesticides in food crops.
Table salt is a commodity frequently contaminated with heavy metals from sea water. The heavy metals of the greatest concern in sea water and thus in table salt, considering the health risks, are, copper, zinc, cadmium (mainly affects the renal functions), mercury and lead (adversely affects the haematological, central nervous and renal systems). M. Hutton's “Human health concerns of lead, mercury, cadmium and arsenic” notes that arsenic affects a large number of organs and systems including the skin, lungs, liver, cardiovascular system, nervous system, haematopoietic system (creation of the cells of blood) and reproductive system. Since salt is an essential additive which is routinely added to most foods, not only for improving taste but also as a preservative to many canned, salted and pickled or fresh foods, the presence of heavy metals could cause adverse effects among a high percentage of the population.
Similarly, the accumulation of mercury in tissues of certain types of fish has been reported and the preference for fish in Sri Lanka as a protein source poses a possible risk of high mercury intake through fish consumption. Organic mercury compounds are toxic to the central nervous system and teratogenic (any agent that causes an abnormality following foetal exposure during pregnancy) to the foetus. G. Pandey, S. Madhuri and A.B. Shrivastav's "Contamination of mercury in fish and its toxicity to both fish and humans: An overview" mentions that mothers exposed to high levels of mercury could give birth to babies with psychomotor retardation, blindness, deafness and seizures.
Formaldehyde is a chemical substance and its addition to various foods including fish poses health risks. It is extremely noxious for human health, being the cause of a variety of illnesses including different forms of cancer and leukemia. Formaldehyde is identified as a carcinogen in humans by the International Agency for Research on Cancer ("Monographs on the evaluation of carcinogenic risks to humans") and the National Toxicology Programme of the World Health Organisation ("Chemical agents and related occupations”).
Aflatoxins are a group of mycotoxins and a high incidence of aflatoxins is reported in food groups including peanut, chillies, and tree nuts in the field and during storage. Aflatoxins are, as mentioned in J.L. Herrman and R. Walker's “Risk analysis of mycotoxins”, a potential carcinogen and may adversely affect all organ systems, especially the liver and the kidneys.
Reduction of hazards
A food fraud that is reported in Sri Lanka is the adulteration of used tea for reselling by the addition of artificial colourings. Artificial colourants are permitted for use as synthetic colours in specific food items and tea is not included in this list. Colour adulteration is strictly prohibited from a consumer health point of view and the colouring of tea has gradually become a matter of serious concern currently.
It is important to assess these hazards in commonly consumed foods in order to identify the magnitude of the problem and to take remedial measures. Contaminant levels in food can be reasonably reduced through best practices such as good agricultural practices and good manufacturing practices. If good hygiene is not practised, yoghurt, a dairy product commonly consumed in Sri Lanka, also gets contaminated with spoilage and pathogenic microorganisms. A Brazilian study elaborates that the presence of coliforms usually indicates failures in hygienic practices in food preparation while Escherichia coli indicates faecal contamination, leading to possible food safety related issues. However, the microbial quality of yoghurt greatly varies with the brand due to varying degrees of best practices followed by the manufacturers.
According to the Codex Alimentarius Commission's “(2019). Codex general standard for food additives, CODEX STAN 192-1995, Rev. 3-2001”, the maximum levels and maximum permissible limits which are the maximum concentrations of a particular substance recommended to be legally permitted in that commodity, are specified for these food safety hazards nationally and internationally so as to ensure the safety of consumers. In Sri Lanka, the competent authority which is responsible to ensure food safety is the Food Control Administration Unit (FCAU) of the Ministry of Health and it is responsible for the protection of consumers’ health by ensuring that foods that are imported, produced, marketed, distributed and consumed meet the highest standards of food safety and hygiene by conforming to the identified limits.
Role of pesticides
Considering the public concern over food safety and also to ensure the supply of safe food by producers and manufacturers, the FCAU took the lead in conducting a baseline survey of these food safety hazards covering a wide range of food contaminants islandwide. Food items and food safety hazards were determined before the inception of the survey based on the inputs from experts of the FCAU and the Food Advisory Committee. One authorised officer was selected from each Regional Director of Health Services (RDHS) area for sample collection. The RDHA areas are compatible with Districts except in the Ampara District where it is divided into two RDHS areas, namely, Ampara and Kalmunai. Each selected authorised officer was instructed to collect three samples (one kilo each) from each food item (vegetables [tomato, brinjal {eggplant/aubergine}, leek, carrot, bean, long bean, ridged gourd, snake gourd, okra/ladies finger], green leaves [gotukola {pennywort}, mukunuwenna {spinach}], fruits [papaw, pineapple, banana, watermelon, mango, guava, local grape], salt, fish, chillie powder, peanut, coconut oil, tea, red rice, and yoghurt). Three samples representing three locations were collected for each item and sampling was done in such a way that the first sample was collected from the biggest market in the centre of the RDHS area and each of the other two samples were collected from a marketplace approximately in the middle of the east and middle of the west from the central place. Samples were collected from all 26 RDHS areas from June-December in 2018 and transported to the pre-identified laboratories following standard sample transporting procedures. Solvents, chemicals and reagents were used in this study.
Pesticide residues in selected vegetables, green leaves and fruits were tested at the Government Analyst's Department. Pesticide residues in foods were tested and 21 pesticides were tested.
Salt samples were tested for heavy metals at the laboratory of the Sri Lanka Standards Institution (SLS).
Mercury and formaldehyde in fish were tested at the National Aquatic Resources Research and Development Agency (NARA) laboratory.
Tea and rice samples were tested for artificial colouring compounds at the Food Laboratory of the National Institute of Health Sciences (NIHS), Kalutara.
Chillie powder, peanut and coconut oil samples were tested for aflatoxins at the NIHS food laboratory.
Microbiology parameters in yoghurt were tested at the Medical Research Institute.
The proportions and percentages of hazards were calculated for each food item in comparison to a recommended standard. For pesticide residues, the MRLs were identified based on the Control of Pesticides (Time Limits) Regulation published under the Control of Pesticides Act. When a national MRL was not specified, the Codex Standard was used. When both standards were not available for a particular pesticide, 0.01 milligram/kilogram was taken as the MRL.
In this baseline survey, greater attention was given to identifying the presence of residues of selected pesticide types in order to understand the food safety associated with commonly consumed fruits, vegetables and green leaves.
The highest percentage of samples with pesticide residues exceeding the MRL was detected in guava (49.18%) followed by grape (28.57%). One pineapple sample drawn from Jaffna was positive for six types of pesticides. In mango, five types of pesticides were identified, all exceeding the MRLs. One mango sample collected from Vavuniya was positive for five types of pesticides.
Guava was the most commonly contaminated fruit found in this survey.
Of the vegetables tested, the percentage of samples detected with the presence of at least one type of pesticide residue were 41.8% in tomato, 21.74% in snake gourd, 18.18% in ridged gourd, 15.91% in brinjal and 15% in long bean. The highest percentage of samples with pesticide residues exceeding the MRLs was detected in tomato (20.59%). Pesticides were not identified in okra. The detected amount of the commonest pesticide residue identified in tomato was well below the MRLs. Only one pesticide was detected in bean and long bean, and the detected levels exceeded the MRLs.
Two fifth of “mukunuwenna” and “gotukola” samples were detected with pesticide residues above the MRLs.
This survey assessed 397 fruits, 199 vegetables, and 85 green leaf samples for pesticide residues and of them, 13.1% of fruit samples, 18.59% of vegetable samples and 48.24% of green leaf samples were detected with the presence of at least one type of pesticide. Pesticide residues exceeding the MRLs were detected in 10.08% of the fruit samples, 11.56% of the vegetable samples and 41.18% of the green leaf samples. Seven types of pesticides were not detected in any of the food items tested for pesticide residues.
According to the results, it can be interpreted that the risk of pesticide residues is the highest in green leaves, followed by vegetables, and it is lower in fruits. Some samples were detected with the presence of several pesticide types and all the three samples collected from certain RDHS areas were positive for pesticides. A higher risk is posed by samples having residues of several pesticides especially when they exceeded the MRLs. It is noticeable that guava is posing a higher risk to consumers compared to other fruit types. Next to guava, grapes also pose a considerable risk that consumers should be aware of. In terms of vegetables, tomatoes exert the highest risk.
P.W.Y. Lakshani, M.K.L.K. Rajapaksha and K. Sendthuran's “Pesticide residues in selected vegetables in several growing areas by gas chromatography/mass spectrometry using the QuEChERS technique (a solid phase extraction technique for sample preparation)" found pesticide residues in vegetables including tomato, capsicum and cabbage and that 30 out of 90 (33.3%) were contaminated with pesticide residues in vegetables sold in open markets in the Nuwara Eliya, Puttalam and Matale Districts. Further, in Sri Lanka, an issue exists with regard to the use of unpermitted pesticide types. M.T. Padmajani, M.M.M. Aheeyar and M.M.M. Bandara's "Assessment of pesticide usage in upcountry vegetable farming in Sri Lanka" found that about 5% of the active ingredients of pesticides used in upcountry vegetable farming in the Badulla and Nuwara Eliya Districts belong to the unpermitted Class (ib) type, while another 34% belong to the category of restricted use (Class [ii]) and that about 47% of the farmers prefer to use the organophosphate group of insecticides, as they believe that these pesticides give quick results and are cheaper despite their toxicity and harmful nature on the environment.
None of the salt samples were detected with levels above the MRLs.
The levels of heavy metals such as arsenic, lead, cadmium and mercury in table salts sold in markets in Sri Lanka do not exceed the maximum permissible limits, thereby conforming to national standards. This may be, according to Gamlath et al., associated with good practices related to production, in order to meet specifications in standards.
Mercury was detected in 31 (43.66%) of the 71 fish samples tested, but all were below the maximum permissible limits. A total of 12 (16.67%) fish samples were identified as having formaldehyde but only two (2.78 %) drawn from the Kegalle and Monaragala Districts exceeded the maximum permissible limits.
The mercury levels in the fish samples were below the maximum permissible limits. In contrast, B.K.K.K. Jinadasa, L.R.S. Rameesha, E.M.R.K.B. Edirisinghe and R.M.U.S.K. Rathnayake's “Mercury, cadmium and lead levels in three commercially important marine fish species in Sri Lanka” reported that 57% of swordfish samples exceeded the maximum permissible limits of European legislation while none of the samples of yellowfin tuna and snapper exceeded the maximum permissible limits, and therefore recommended that higher levels of mercury in swordfish need to be considered when dealing with particularly sensitive population groups such as pregnant females, lactating mothers, infants and children. B.K.K.K. Jinadasa, E.M.R.K.B. Edirisinghe and I. Wickramasinghe's “Total mercury, cadmium and lead levels in the main export fish of Sri Lanka” again reported that in terms of the mercury levels in swordfish, yellowfin tuna, black marlin and red snapper, swordfish showed the highest, and the lowest was recorded for red snapper but that the total mercury levels in yellowfin tuna and red snapper have not exceeded the maximum permissible limits while marlin and swordfish had exceeded the maximum permissible limits, and also that the total mercury levels vary in different months of the year (in swordfish, higher levels were observed in August and September).
Preventive measures
In Sri Lanka, regulations on formaldehyde in fish came into operation in 2010. In this survey, about 17% of the fish samples showed the presence of formaldehyde and about 3% exceeded the maximum permissible limits. P.G.D. Madusha, G.J. Ganegamaarachchi, P.H. Ginigaddarage, K.W.S. Ariyawansa, I. Wickramasinghe, K.S. Hettiarachchi, S. Abhayarathne and R. Perera's “Quality assessment of imported fish retailed in Sri Lanka” reported that the formaldehyde levels in swordfish, squids, Indian scad and bullet tuna species were well below the maximum permissible limits. However, attention needs to be given to assure that market sold fish do not exceed the safe limits.
About one fifth of the raw red rice samples were detected with artificial colouring and these samples were drawn from the Colombo, Ampara, Badulla and Mullaitivu RDHS areas. Two colourings were identified in one red rice sample drawn from the Galle RDHS area. Both these colourings are permitted in Sri Lanka, but not allowed to be used in rice or tea.
Tea is the most commonly consumed beverage in Sri Lanka and none of the analysed samples showed any artificial colouring. Surveillance programmes are currently in progress in order to identify the possible adulteration of rice and tea with artificial colourants.
Levels of Aflatoxins exceeding the levels were detected in eight (10%) coconut oil samples, nine (11.25%) peanut samples and 15 (18.75%) chillie powder samples. More than one 10th of the chillie powder samples were detected with aflatoxins exceeding the MRLs. These samples were drawn from the Colombo, Kalutara, Nuwara Eliya, Batticaloa, Matale, Gampaha and Ampara RDHS areas. Peanut samples drawn from the Mullaitivu, Kilinochchi, Batticaloa and Kegalle RDHS areas showed levels of aflatoxins above the level and three peanut samples were detected with values above the level, with the highest being from Batticaloa, Kilinochchi and Mullaitivu. A level of aflatoxins more than the permitted level was detected only in one coconut oil sample drawn from the Trincomalee RDHS area.
N.B. Karunarathna, C.J. Fernando, D.M.S. Munasinghe and R. Fernando's “Occurrence of aflatoxins in edible vegetable oils in Sri Lanka” revealed that out of 32 coconut oil samples, 12 (37.5%), which included five branded and seven unbranded products, had total aflatoxins’ contamination and aflatoxin B1 contamination while the 10th and 11th samples exceeded the European Union’s maximum permissible levels applicable for total aflatoxins and aflatoxin B1.
All the yoghurt samples (42) complied with the microbiological specifications given in the SLS standards for yoghurt. Strict hygienic practices and protocols followed by the Sri Lankan dairy factories may be the reason for this. In contrast, K.K.G.U. Hemamali, V.S. Jayamanne and S.M. Amarathunge's “Physicochemical and microbiological quality of some consumer preferred plain set yoghurts sold in the Matara Municipal area” reported that all microbiological parameters of all yoghurt brands were not within the permissible range of local and international standards. R.M.U.S.K. Rathnayaka and K.L.S.R. De Silva's “Physicochemical sensory and microbiological evaluation of set and fruit yoghurt in the Sabaragamuwa Province” reported that the total plate count and total yeast and mould count of certain commercial set yoghurt samples were not within the SLS standards. Therefore, continuous surveillance would be the strategy to monitor food safety and quality parameters of yoghurt brands available in the market.
Pesticide residues exceeding the MRLs were detected in 10.08% of the fruit samples, 11.56% of the vegetable samples and 41.18% of the green leaf samples. Salt was free from heavy metals. Mercury and formaldehyde were detected in fish samples but the mercury levels did not exceed the maximum permissible limits. Artificial colouring was not detected in tea but was found in red rice. Levels of Aflatoxins exceeding the limits were detected in 1.25% of coconut oil, 5% of peanut and 11.25% chillie powder samples. Yoghurt samples were free from microbiological contamination.