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CRP Success story: Enhancing Food Safety Through Improved Testing for Mixed Contaminants and Residues

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Tasty and nutritious as they are, fruits can be exposed to a range of chemical contaminants such as mycotoxins, pesticides and persistent organic pollutants. These can be controlled using techniques developed under the coordinated research project.  (Photo: J. Sasanya/IAEA)

Food safety is key to protecting public health and trade in food products. Worldwide, exposure to chemical hazards in food, as well as in drinking water and animal feed, is currently managed on the basis of health risk assessments for individual hazards. However, consuming food and water can expose people to a range of contaminants and residues simultaneously. For example, the use of veterinary drugs and pesticides to protect livestock and crops may result in the presence of hazards in food. Risk assessment should therefore depend on data generated on mixed contaminants and residues. Yet few countries have the capacity and analytical techniques to test such “cocktails” of hazards.

A recently concluded coordinated research project (CRP) has resulted in the development of 25 analytical methods for simultaneous measurement of a mixture of chemical hazards in a range of foods. It also developed locally produced material for use with radiotracers to screen residues and contaminants in food, as well as cost-effective and environmentally friendly sample preparation techniques. Furthermore, the project generated information relevant to antimicrobial resistance (AMR), which affects public and animal health.

The CRP Objectives

The overall objective of the CRP was to enhance the food and environmental safety control systems and risk assessment programmes of Member States by improving laboratory capabilities for gathering reliable data on mixed contaminants and residues in foods, as well as on antimicrobial use pertaining to the development of AMR.

The specific objectives were to:

  • Investigate the effective application of newly researched methods in the routine surveillance of mixed contaminants and residues in foods and where possible establish base/reference “fingerprints” of food matrices that may contain a mixture or cocktail of contaminants and/or residues.
  • Research the development, optimization/adaptation, and validation of analytical methods for mixed contaminants and residues in foods and associated matrices.
  • Research the development of innovative generic sample preparation techniques for mixed contaminants and residues in foods and associated matrices.
  • Investigate the development, optimization/adaptation, validation and application of sensitive and selective multi-antimicrobial analytical methods useful for monitoring residues of substances associated with development of antimicrobial resistance.

Impact and relevance

The analytical methods established under the CRP have contributed to improved laboratory performance in 13 countries, which are now able to analyze multiple chemical hazards such as mycotoxins, pesticide residues, and veterinary drug residues simultaneously using single methods, rather than testing each group of hazards using individual methods. Over 300 residues and contaminants in at least 17 food types and commodities can be tested. Some of the methods have been applied to routine testing and in national monitoring programmes responsible for the control of foods for local consumption and export. The methods are transferrable to other countries.

The CRP developed and validated miniaturized low solvent-use and resource-saving isotope-assisted sample preparation methods, which can help laboratories conduct efficient and cost-effective food safety testing. These methods are also eco-friendly, as fewer chemicals are used and released into the environment.

An innovative, cost-effective radioreceptor assay (RRA) technique using carbon-14 and tritium (H-3) labelled radiotracers for analysis of drug residues and mycotoxins was developed using receptors produced locally in the research laboratory. The RRA depends on commercial kits, which can be difficult to procure and deliver to end users. Based on the CRP’s findings, Member States can start producing receptors themselves locally and reduce the cost of kits. The receptors have been packaged into commercial-like tablets and plans are in place to scale up production for sharing with other countries. The CRP optimized the performance of other inputs (consumables) such as buffers, as well conditions including temperature, pH and stability; the protocols are being shared with other laboratories.

The CRP also developed, validated and used four analytical methods to investigate the presence of antimicrobial residues vis-a-vis associated resistant pathogens, which are relevant to the global fight against AMR. In one method for testing 20 antimicrobials using the stable isotope-labelled drugs flunixin-d3 and penicillin G-d7, a correlation was established between the residues of seven drugs (oxytetracycline, enrofloxacin, amoxicillin, trimethoprim, cephalosporins procaine-benzylpenicillin and sulfonamides) in food and animal waste samples and the presence or absence of antimicrobial resistance genes in bacteria such as Escherichia coli. High (100%) bacterial resistance to beta-lactam antimicrobials such as ampicillin, cefotaxime, ceftazidime and cefepime was determined. Resistance to sulfamethoxazole was also detected.

The CRP had significant academic and human resource-development benefits, training ten PhD, 15 MSc and two undergraduate students.

Sixteen research contract and agreement holders from Benin, Botswana, Canada, Chile, China, Colombia, Ecuador, Italy, the Netherlands, North Macedonia, Pakistan, Papua New Guinea, Peru, South Africa, Spain and Uganda participated in this CRP.

Managing diseases in livestock requires use of veterinary drugs and pesticides the residues of which are a public health and trade concern. Animal products such as milk may also contain mycotoxins,  and are associated with antimicrobial resistance. (Photo: J. Sasanya/IAEA)

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