Evaluation of the chemical residue monitoring in animal-derived products in Switzerland

Abstract

This paper evaluates whether the Swiss monitoring programme for foreign substances in animal products fulfils basic epidemiological quality requirements, and identifies possible sources of bias in the selection of samples. The sampling was analysed over a 4-year period (2002–05). The sampling frame in 37 participating abattoirs covered 51% of all slaughtered pigs, 73% of calves, 68% of beef and 36% of cows. The analysis revealed that some sub-populations as defined by the region of origin were statistically over-represented while others were under-represented. The programme that is in accordance with European Union requirements contained some relevant bias. Patterns of under-sampled regions characterized by management type differences were identified. This could lead to an underestimate of the number of contaminated animals within the programme. Although the current sampling was stratified and partially risk-based, its efficiency could be improved by adopting a more targeted approach.

Keywords:

• Bias
• bovine
• Council Directive 96/23/EC
• foreign substances
• monitoring programme
• pigs
• residues
• Switzerland

Acknowledgements

The authors are grateful to Hans-Jörg Heiz from the Federal Veterinary Office for sharing all his data and for his input regarding the description of the monitoring programme.