Chloramphenicol is a broad-spectrum antibiotic with very high bacteriostatic action potential that has been used in veterinary and human medicine. Due to massive side effects, its use in human medicine is now severely restricted. Since 1994, chlorampenicol has been banned in the EU for use in food-producing animals. The ban is based on the suspicion that chloramphenicol can cause aplastic anemia (reduction/cessation of blood cell production by the bone marrow) in humans, as well as evidence of possible embryo/fetotoxicity and reproductive toxicity.

If chloramphenicol is used, it can enter the organism and thus animal foods.

Monitoring food for chloramphenicol residues.

Because residues of chloramphenicol in food at any concentration can pose a risk to consumer health, food of animal origin is intensively monitored.

For the control of domestic foodstuffs for misuse of chloramphenicol, there is a comprehensive testing program within the framework of the National Residue Control Plan (NRKP) in the sense of preventive consumer protection.

Furthermore, samples are examined within the framework of actions of the official food control as well as in cases of suspicion. Special attention is paid to the control of products from countries outside the EU (e.g. aquaculture products from the Southeast Asian region, honey from China, etc).

Third countries importing products into the EU must guarantee that their residue monitoring measures are at least equivalent in effect to those of the Residue Control Directive 96/23/EC. However, since in many countries outside the EU the use of chloramphenicol is allowed and practiced because of its high efficacy potential and low price, third country products are intensively controlled.

In total, between 1100 and 1200 samples per year are tested for chloramphenicol in the Department of Veterinary Medicinal Products, Hormones and Contaminants of the Institute for Food Safety Vienna.

Examined matrices

• Blood
• Animal tissues (especially muscle)
• Aquaculture (fish, shrimp, mussels)
• Milk
• Eggs
• Honey

Analytical strategy and methods

For the purpose of uniformity in analytical performance and interpretation of results across the EU, an RPA (reference point for action) of 0.3 µg/kg has been set for chloramphenicol (CommissionRegulation (EU) 2019/1871; the RPA will be lowered to 0.15 µg/kg from 28.11.2022). This means that, firstly, the detection limits of the laboratories must be below the RPA and, secondly, results above the RPA must be judged as positive ("non-compliant"). Foods with chloramphenicol concentrations below the RPAaremarketable, but the cause of the residues is being investigated.

In the Department of Veterinary Medicinal Products, Hormones and Contaminants of the Institute of Food Safety Vienna, we analyze chloramphenicol in food of animal origin and are also the National Reference Laboratory for these studies.

Regular participation in international interlaboratory comparisons and in workshops of the EU Reference Laboratory (EURL) in Fougères (France), which is responsible for antibiotics, ensure the quality of the results and constant further development of the analytical methods to the latest state of the art and research.

In the interest of rapid and cost-effective screening, a two-step approach is generally used:

• Screening Screening methods are designed for rapid sample throughput, with a maximum false negative rate of 5% according to Commission Implementing Regulation (EU) 2021/808. Immunochemical methods (Beadyplex, Infiniplex, ELISA) are used for this purpose depending on the matrix.
• Confirmatory analysis This step is used for confirmation and quantification in case of non-negative screening results. According to Commission Implementing Regulation (EU) 2021/808, a mass spectrometric method is required for the confirmation of prohibited substances. The method used involves liquid/liquid extraction for sample cleanup followed by liquid chromatographic separation with mass spectrometric detection (LC-MSMS).

Legal basis

Commission Regulation (EU) No. 37/2010 of 22 December 2009 on pharmacologically active substances and their classification with regard to maximum residue limits in foodstuffs of animal origin (OJ EU No. L 15, 20.1.2010).

Council Directive 96/23/EC [SD5] of 29 April 1996 on measures to monitor certain substances and residues thereof in live animals and animal products (OJ No. L 125, 23.5.1996).

COMMISSION REGULATION (EU) 2019/1871 of 7 November 2019 concerning reference points for action on non-authorized pharmacologically active substances present in food of animal origin and repealing Decision 2005/34/EC.

COMMISSION IMPLEMENTING REGULATION (EU) 2021/808 of 22 March 2021 concerning performance criteria for methods of analysis for residues of pharmacologically active substances in food-producing animals and the interpretation of results and methods to be used for sampling and repealing Decisions 2002/657/EC and 98/179/EC.