Environmental Engineering Reference
In-Depth Information
air, water, soil or sediment. A range of factors and processes including the
physico-chemical properties of the compound and the characteristics of the
receiving environment will affect distribution.
Whilst pharmaceuticals will have been released to the environment for
decades, it is only recently that attempts have been made to quantify the levels
of these compounds in the environment. Using new analytical techniques such as
Liquid Chromatography Tandem Mass Spectrometry (LC-MS-MS), low levels of a
range of pharmaceuticals, including hormones, steroids, antibiotics and parasiti-
cides are now being detected in soils, surface waters and groundwaters inter-
nationally (e.g., Hirsch et al.
1999
; Kolpin et al.
2002
). Whilst the reported
concentrations are generally low (i.e., sub
m
gL
1
in surface waters), the substances
have been observed across a wide variety of hydrological, climatic and land-use
settings and many of the substances have been detected throughout the year. As a
result, questions have been raised over the impacts of veterinary medicines on
organisms in the environment and on human health.
Impacts on the environment and human health
In the EU and North America, the environmental risks of human and veteri-
nary medicines now need to be assessed before a product can be marketed and
in order to perform the risk assessment, data are often required on the effects
on aquatic and terrestrial organisms (Breton & Boxall
2003a
). A reasonable
body of data is therefore available on the effects of many medicines on aquatic
invertebrates, fish and algae, earthworms, plants and soil microbes (e.g., see
Boxall et al.
2004a
). These data have generally been obtained using standard
ecotoxicity studies and the studies are often short lived with mortality as the
endpoint. Generally, effects occur at much higher concentrations than those
measured in the environment.
However, pharmaceutical compounds are either designed to be highly active
and interact with receptors in humans and animals or they are toxic towards
health, threatening organisms such as bacteria, fungi and parasites. Many
lower animals have receptor systems similar to humans and animals, moreover
many of the groups of organisms that affect human and animal health and
which are targeted by pharmaceuticals play a critical role in the functioning
of ecosystems. It is therefore possible that pharmaceuticals may cause subtle
effects on aquatic and terrestrial organisms that might not be picked up in
standard studies. For human medicines in particular, releases to the environ-
ment are likely to be almost continuous so organisms will be exposed for much
longer durations than those used in standard tests. Because of this, researchers
have begun to investigate some of the more subtle effects caused by long-term
low-level exposure to pharmaceuticals. A wide range of subtle impacts have
been reported so far (e.g.,
Table 5.2
) including effects on oocytes and testicular
maturation; impacts on insect physiology and behaviour; effects on dung
