Comparative and Veterinary Pharmacology

KeywordsVeterinary medicines
Environmental fate
Ecotoxicity

Environmental risk

1 Introduction

Following administration to an animal patient, drugs are absorbed and in some
instances may be metabolised. The parent compound(s) and any metabolites may
then be released into the environment directly, for example, the use of medicinal
products in fish farms, and indirectly, via the application of animal manure (con-
taining excreted products) to land or via direct excretion of residues onto pasture
(Jørgensen and Halling-Sørensen 2000 ; Boxall et al. 2003 ; Boxall 2004 ; Sarmah
et al. 2006 ). Once in the environment, veterinary medicines and their metabolites
have the potential to affect aquatic and terrestrial communities and may also enter
drinking water supplies and the human food chain. This chapter reviews the present
state of the understanding of the inputs of livestock medicines to the environment
and synthesises the available information on the fate, transport and effects of
veterinary medicines in the environment. Gaps in current knowledge are high-
lighted and recommendations made for future research.

2 Routes of Input to the Environment

The main routes of input to the soil and aquatic environments and subsequent
transport routes are illustrated in Fig. 1. Compounds may also be released during
the manufacturing process. During livestock production, veterinary drugs enter the

Intensively

reared

Pasture Aquaculture

Manure

Dirty water storage

Soil

Degradation Leaching Runoff or

Drainflow

Degradates Groundwater Surface water

Fig. 1Routes of entry of veterinary medicines to the environment

292 A.B.A. Boxall