(FAO–WHO 1996 ). Surveillance programmes, in contrast, sample tissues from
animals suspected of violative residues on the basis of clinical signs or herd history.
If monitoring reveals a potential residue problem, the action taken will vary in
accordance with the policies of the specific jurisdiction. Typically, the source of
supply is traced and action is taken to avoid further occurrences. Action may
include seizure and disposal of produce, additional residue testing at the cost of
the producer, quarantining a farm and preventing the sale of produce until the
commodity has been found to be safe for consumption and fit for sale in both
domestic and export markets. Auditing of users and operators, seeking feedback
from resellers, and implementing industry codes of practice may also be used to
augment residue monitoring.
4 Non-regulatory Mechanisms for the Control
of Drug Residues
4.1 The Role of the Veterinary Pharmaceutical Industry
Significant advances in pharmaceutical formulations and drug delivery technolo-
gies have resulted in improved efficacy and drug residue profiles of products for use
in food-producing animals. Studies into specific compounds involve proprietary
data and such studies are rarely published. However, one report described the
process of selecting a compound (eprinomectin) from a number of potential drug
candidates on the basis of optimal efficacy and residues profiles (Shoop et al. 1996 ).
Reports such as this in the open literature highlight the considerable efforts of the
veterinary pharmaceutical industry in developing products with low residues.
Recent advances in pharmaceutical sciences are also providing potential solutions
to residues at injection sites. For example, studies indicate that biodegradable
polymers may be suitable for use as drug carriers in injectable microspheres and
microcapsules (Yazar et al 2006 ) (see also chapter, “Drug Delivery Systems in
Domestic Animal Species”). Liposomes that are potential candidates for the intra-
muscular delivery and sustained release of drugs in food-producing animals have
also been reported (Sallovitz et al. 1998 ).
4.2 The Roles of Producers, Veterinarians and Food Processors
The importance of responsible use of veterinary drugs on-farm cannot be over-
emphasised. The implementation of quality assurance programmes by producers
has resulted in a decreased incidence of violative residues (Roeber et al. 2001 ). This
result is contributed to in part by carefully observing directions for use, including
withdrawal periods in product labelling. In the case of injectable veterinary drug
286 P.T. Reeves