potential concern so this is an area where further research is warranted. It is
important to recognise that for many of these substances data were lacking on the
major environmental fate processes so the estimates of exposure are likely to be
extremely conservative.
6 Recommendations for Future Research
Over the past 10 years there has been increasing interest in the impacts of veterinary
medicines in the environment and there is now a much better understanding about
how veterinary medicines move around the environment, how they persist in the
environment and their impacts on aquatic and terrestrial organisms. However, there
are still a number of uncertainties that require addressing before there can be a full
understanding of the environmental risks of veterinary medicines. Areas requiring
further research include:
l Usage data are unavailable for many groups of veterinary medicines and for
several geographical regions, which makes it difficult to establish whether these
substances pose a risk to the environment. It is therefore recommended that
usage information be obtained for these groups. Better usage data will assist in
designing more robust hazard and risk management strategies that are tailored to
geographically explicit usage patterns.
l Information on the potential environmental effects of veterinary medicine trans-
formation products is lacking. It is likely that most metabolites will be less toxic
than the parent compounds, but this may not necessarily always be the case.
l The relative significance of novel routes of entry to the environment from
livestock treatments, such as wash-off following topical treatment and farm
yard runoff, and aerial emissions, have not generally been considered. For
example, the significance of exposure to the environment from the disposal of
used containers or from discharge from manufacturing sites should be investi-
gated further.
l Monitoring data are available for a small number of veterinary medicines in the
soil, sediment, surface waters and groundwaters. Further targeted monitoring
should be performed to determine concentrations in the environment. These data
could then be used along with the existing data to evaluate current risk assess-
ment exposure models.
l For many veterinary drugs, information is lacking in the literature on their
ecotoxicity. Moreover, in instances where data are available, the studies have
generally focused on short-term acute endpoints, Studies should be conducted to
assess the potential impacts of those veterinary medicines for which ecotoxicity
data is lacking but are seen to regularly occur in the environment. The potential
sub-lethal impacts of these substances should also be explored.
l Although information is available on the direct effects of a range of veterinary
medicines on aquatic and terrestrial organisms, limited information is available308 A.B.A. Boxall