Development and Strengthening of Radio-Analytical and Complementary Techniques to Control Residues of Veterinary Drugs and Related Chemicals in Aquaculture Products

The CRP has met intended goals with significant benefit to Member States. A range (37) of nuclear, isotopic and complementary analytical methods including many that are easy-to-use, relative quick and broad spectrum were developed, validated or adapted and applied. These are transferable in the form of standard operating procedures (SOPs) already prepared. Some of this work has also been published as 23 papers or scientific reports and 5 conference proceedings. The methods have contributed to improved analytical technology for the testing and monitoring of residues and contaminants in aquaculture products (local/exports and imports) and production sites. CRP work also contributed to enhanced laboratory competences including ISO 17025 accreditation of the CSIs in Nigeria, South Africa and Uganda for example. It also enhanced human resources development such as the 17 PhD, MSc and Post-Doctoral fellows that benefited and at least 216 scientists/students trained, through TCPs. Six expert missions were also implemented. Some research findings have contributed to the development of national and regional TCPs.
Singapore – Established methods are used in the national residue control program to effectively assist aquaculture/seafood import regulation and local farm surveillance. A wide range of residues and contaminants (including those unanticipated and prohibited) were detected, resulting in review of the country’s residue control programme to monitor the additional chemical contaminants in aquaculture products. As a net importer, it is important to expand the scope of hazards to monitor. Isotopic techniques were used to determine the presence of chemical used in commercial cleaning products (e.g. benzalkonium chloride) in catfish fillet and smoked salmon.
Brazil (Microbioticos and CENA) – A spectrometric method was established for analysis of residues especially of forbidden substances such as Chloramphenicol in fish and shrimps. This is useful for the Brazilian National Residue and Contaminant Monitoring programme where the CSI Microbioticos is a partner. This is needed to facilitate export of animal products. A radio immuno assay technique has also been established. Research was successfully conducted on the uptake and depletion of a C-14 labelled drug (sulfonamide) in rainbow trout fish. This information is important in appreciating the metabolism of the drug and provides a foundation for additional research on depletion of drugs in food animals. Such information is useful in the process of MRL setting. Assessment of C-14 sulfadiazine on Danio rerio (zebrafish) was also done to evaluate the bioconcentration and depuration of sulfadiazine which is also important for MRL setting and risk assessment.
South Africa – Broad spectrum analytical methods were established, accredited and being used to implement a national residue monitoring programme for antimicrobials residues (and related hazards) in aquaculture products and their production sites. Aquaculture contributes ~ R0.7 billion or 0.2% to the South African GDP. CSI investigated the potential consumer risk of exposure to per- and polyfluoro-alkyl substances (PFAS) in aquaculture products. This could lead to extensive risk assessment and subsequent inclusion of per- and polyfluoro-alkyl substances (PFAS) in the national residue monitoring. An analytical method was also established for mycotoxins in feed and aquaculture/fish samples in South Africa
China – New analytical methods were developed/validated and applied to the testing of veterinary drugs and shellfish toxins in fish/aquaculture products in South China. Methods have been applied to a residue surveillance scheme not only in local Shenzhen city but also in Guangdong province. The research generated information to help confirm that the presence of certain forbidden drugs/substances in food production, is not necessarily due to intentional use, rather due to natural occurrence. For example, a research contract showed that Semicarbazide (SEM, a nitrofuran metabolite) is not a conclusive marker for illegal use of the forbidden antimicrobial nitrofuran because SEM was found to be naturally existing in shellfish. Established occurrence-species profile for SEM in shellfish may help in food safety regulatory decisions.
Cameroon – New radio receptor assay methods established under the project have been used for cost-effective determination of 5 major groups of veterinary drug residues in different fish following primary and secondary validation. Information has been gathered (in aquaculture in Cameroon) on: (a) the practices as well as the types of antimicrobials commonly used by fish farmers; (b) The contamination level of aquaculture products and sites (mud and water) by veterinary drug residues, mycotoxins and microbial contaminants. Findings suggest the need of a regular monitoring of antimicrobials residues not only in fish but also in its direct environment as well. Aflatoxins were found in fish feeds, muds collected from the farming ponds and in catfish. These suggest that attention should be paid to the quality of ingredients used for fish-feed.
Argentina – Analytical techniques using a range of stable isotopes, were established to measure presence of pharmaceuticals in fish, water and sediments. Local and imported fish including farmed salmon were also investigated for presence of antimicrobials. Research findings also contributed knowledge and better understanding of chemical contamination/residue levels in water and related matrices and potential implication to aquaculture production in general. Stable isotope-based methods were used to determine the presence of a wide range of human and veterinary pharmaceuticals in fish and water, as an indication of human/anthropogenic exposure. Bioaccumulation and bioconcentration of certain drugs used in human medicine such as carbamazepine, in fish for human consumption, under field and controlled laboratory experiments, has been demonstrated.
Ecuador – Broad spectrum antimicrobial analytical techniques were developed, validated and applied by the CSI to ensure safety of aquaculture products consumed locally and for export. Exporters utilize the services offered to certify shrimp for the market.
Uganda – Established radio receptor assay techniques used for the detection of 5 major groups of antimicrobial residues in 7 aquaculture fish. Complementary techniques were also developed for quantification of drug residues in fish and other samples; metals in fish and mycotoxins in feed useful for fish production. All are used to support testing programmes in the country.
Nigeria – Radio receptor assay techniques for the analysis of antimicrobials in aquaculture/seafood products were established at the National Agency for Food and Drug Administration and Control and successfully used in interlaboratory studies leading to accreditation. The CSI laboratory launched the analysis of veterinary drug residues in aquaculture/seafood products from the local markets, imports and exports. Analysis of other contaminants e.g. toxic metals in fish can also be conducted.