Characteristics of Natural and Urban Soils - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 111

et al. 2004 ), such as soils, lake or sea sediments, groundwater and surface water. This
section concentrates on general rules about the behaviour of hospital contaminants
once they have been dispersed in the soil based on the available research papers
consulted.
Halling-Sørensen et al. ( 1998 ) reviewed the occurrence, fate and effects of
pharmaceuticals in the environment, concentrating on the aquatic environment
including the groundwater. The majority of their literature sources dealt with the
biological impacts on living organisms in media where the effects were quickly
discovered, such as fish farms, or observed by purposeful testing on Daphnia,
algae, various microbial organisms and agricultural crops. Thiele-Bruhn ( 2003 ) and
Hamscher et al. ( 2004 , 2005 ) surveyed the fate of pharmaceutical antibiotics in
soils.

The behavior of pharmaceutical drugs in the environment has been summa-
rized by Velagati as follows ( verbatim) :

• Most pharmaceutical drugs are resistant to partial or complete mineraliza-

tion through biodegradation. Small chain peptides and other natural products
may be mineralized and are, therefore, an exception. Aerobic-anaerobic
cycles of biodegradation may enhance biotransformation and, in combina-
tion with photodegradation, may enhance the potential for depletion.

• Most pharmaceutical drugs are resistant to degradation through hydrolysis.

• In general, pharmaceutical drugs are mostly very poorly soluble in water

and have high partition and adsorption coefficients. These properties con-
tribute to strong adsorption to organic matter and the potential for bioac-
cumulation and bioconcentration. They are very strongly bound to sludge
in the Publicly-Owned Wastewater Treatment Systems (POWTP), and to
soil. Such properties also make them unavailable for microbial degrada-
tion (aerobic and anaerobic biodegradation) and also for hydrolysis and
photo-degradation.

• When bioavailable, pharmaceutical drugs appear to biotransform and min-

eralize in soils more rapidly than in water because of the diversity of
microorganisms present in soils (fungi, bacteria, and actinomycetes). Poor
biotransformation observed under aerobic conditions in the POWTP is likely
to be due to the lack of such diversity (very few fungal and actinomycetes
populations) in microbial populations.

Taken from “Behavior of pharmaceutical drugs (human and animal health)
in the environment”, by Ranga Velagati, PhD, Director, Pharmaceutical
Manufacturing Support Group, Analytical-Biochemistry Laboratories,
Columbia, Missouri. Published in Drug Information Journal, Vol. 1, pp.
715-711, 1997.