animal-derived foods is also facilitated when these principles and methods of the risk
analysis framework are applied consistently amongst countries.
In this chapter, the various studies are discussed under the appropriate section of
the risk analysis framework. However, there are no “hard and fast” rules in this
respect. For instance, the iterative procedure for allocating MRLs in some jurisdic-
tions involves both exposure assessment and risk characterisation.
2.1 Risk Assessment
In developed countries, veterinary drugs are regulated under legislation that
requires their quality, safety and efficacy to be evaluated and deemed acceptable
before marketing approval is granted. The data demonstrating the safety of residues
in edible tissues and in products such as milk and eggs from treated animals relate
principally to toxicology and residue chemistry. The risk assessment also draws on
other disciplines, including pharmacology, microbiology, veterinary medicine,
animal husbandry, epidemiology and statistics.
The assessment of dietary risk is conceptualised in the relationship:
risk¼hazardexposurewhere, “risk” is the probability of harm occurring to the consumer; “hazard” refers
to the chemical residue representing a source of potential harm attributable to its
intrinsic properties; and “exposure” refers to the dietary exposure to the chemical
residue (Davies et al. 2003 ). From this relationship, it is evident that reducing
hazard or exposure or both reduces risk.
The above relationship also highlights a fundamental difference between “haz-
ard” and “risk”. According to the IPCS ( 2004 , p. 12, 13), “hazard” and “risk” are
defined as follows:
Hazard is the inherent property of an agent or situation having the potential to
cause adverse effects when an organism, system, or (sub) population is exposed.
Risk is the probability of an adverse effect in an organism, system, or (sub)
population caused under specified circumstances by exposure to an agent.
The conduct of a food safety risk assessment requires that sufficient data of
adequate quality are available. In recent years, harmonised protocols for toxicolo-
gical food safety assessment have been agreed upon by the International Coopera-
tion on Harmonisation of Technical Requirements for Registration of Veterinary
Medicinal Products (VICH): these can be found on the VICH website (http://www.
vichsec.org/). Additional VICH guidelines for metabolism and residue kinetic
studies are currently under development.
The results of risk assessment are applicable only to the specified test substance;
therefore, the chemical identity and properties of the substance are a critical com-
ponent of the database. Information on chemical identity is provided by inter-
national chemical databases. Also critically important is the information relating
268 P.T. Reeves