the food chain. Various examples have been observed which support the existence of
pharmaceuticals in soil which causes the harmful impact on non-target organisms in
different ways such as alteration in sex ratio of higher organisms, specific changes in
biogeochemical cycles, changes in plant growth, failure of larvae to molt, and
anatomical deformation of various organisms (Pounds et al. 2008; Parolini and
Binelli 2014). Higher concentrations of veterinary antibiotics in swine and chicken
manure indicated immense usage of veterinary antibiotics in swine and chicken
husbandry (Hou et al. 2015).
13.3 Environmental Fate of Pharmaceuticals
Study of the fate of pharmaceutical substances with their released amount is essential. Distribution and fate of pharmaceuticals depend on the range of various factors
like physicochemical properties, their distribution in soils and sediments, and degradation in aquatic and terrestrial environment. Climate and type of soil also influence
the fate and distribution of drugs (Boxall et al. 2003). Generally, drugs rarely
hydrolyzed. Most of the pharmaceuticals absorb inadequately and are also not
absolutely metabolized in animals and human beings. Large amount of the intake
dosage of pharmaceuticals are released via excreta within few hours of its consumption as parent compound or in metabolite form (Zhang et al. 2014a, b). Usually,
pharmaceutical compounds reach the environment in the form of mixtures which are
very dangerous to living beings (Stackelberg et al. 2004). During wastewater
treatment process some pharmaceuticals are not completely degraded and get
released in treated effluents and solid waste. This solid waste is used as fertilizers
on agriculture lands.
Apart from ecological threats, humans are also concerned with its menace. A
large number and various kinds of antibiotics along with their metabolites remain in
reclaimed wastewater varying their composition and concentration (Petrie et al.
2015). When reclaimed wastewater (RWW) is irrigated to the crops it got exposed
in agricultural land with antibiotics as well as antibiotic resistant bacteria. There they
multiply in the soil and may cause severe health impacts to human health. On the
other hand, when soil amendment is done with drug residue containing manure and
biosolids and irrigation is done with RWW, then their residue may undergo with
sorption, desorption, biotic and abiotic transformation process. Thus, they harshly
affect the soil microbiota. Plants uptake the pharmaceutical residues and
bioaccumulate in plant tissues and later enter into the food web (Christou et al.
2017).
The drugs may undergo direct and indirect photolysis and it is the main approach
of abiotic transformation in water streams. In direct photolysis there is direct
absorption of sunlight whereas in indirect photolysis natural photosensitizers take
part (Nikolaou et al. 2007). The dissipation process of pharmaceuticals in the
environment can be inhibited by various procedures. For this, key processes consist
of aerobic and anaerobic biodegradation and abiotic transformation; for instance,
degradation by UV-light, hydrolysis, and sorption. According to the type of drug and
13 Pharmaceuticals: An Emerging Problem of Environment and Its Removal. . .
273
pharmaceuticals in soil which causes the harmful impact on non-target organisms in
different ways such as alteration in sex ratio of higher organisms, specific changes in
biogeochemical cycles, changes in plant growth, failure of larvae to molt, and
anatomical deformation of various organisms (Pounds et al. 2008; Parolini and
Binelli 2014). Higher concentrations of veterinary antibiotics in swine and chicken
manure indicated immense usage of veterinary antibiotics in swine and chicken
husbandry (Hou et al. 2015).
13.3 Environmental Fate of Pharmaceuticals
Study of the fate of pharmaceutical substances with their released amount is essential. Distribution and fate of pharmaceuticals depend on the range of various factors
like physicochemical properties, their distribution in soils and sediments, and degradation in aquatic and terrestrial environment. Climate and type of soil also influence
the fate and distribution of drugs (Boxall et al. 2003). Generally, drugs rarely
hydrolyzed. Most of the pharmaceuticals absorb inadequately and are also not
absolutely metabolized in animals and human beings. Large amount of the intake
dosage of pharmaceuticals are released via excreta within few hours of its consumption as parent compound or in metabolite form (Zhang et al. 2014a, b). Usually,
pharmaceutical compounds reach the environment in the form of mixtures which are
very dangerous to living beings (Stackelberg et al. 2004). During wastewater
treatment process some pharmaceuticals are not completely degraded and get
released in treated effluents and solid waste. This solid waste is used as fertilizers
on agriculture lands.
Apart from ecological threats, humans are also concerned with its menace. A
large number and various kinds of antibiotics along with their metabolites remain in
reclaimed wastewater varying their composition and concentration (Petrie et al.
2015). When reclaimed wastewater (RWW) is irrigated to the crops it got exposed
in agricultural land with antibiotics as well as antibiotic resistant bacteria. There they
multiply in the soil and may cause severe health impacts to human health. On the
other hand, when soil amendment is done with drug residue containing manure and
biosolids and irrigation is done with RWW, then their residue may undergo with
sorption, desorption, biotic and abiotic transformation process. Thus, they harshly
affect the soil microbiota. Plants uptake the pharmaceutical residues and
bioaccumulate in plant tissues and later enter into the food web (Christou et al.
2017).
The drugs may undergo direct and indirect photolysis and it is the main approach
of abiotic transformation in water streams. In direct photolysis there is direct
absorption of sunlight whereas in indirect photolysis natural photosensitizers take
part (Nikolaou et al. 2007). The dissipation process of pharmaceuticals in the
environment can be inhibited by various procedures. For this, key processes consist
of aerobic and anaerobic biodegradation and abiotic transformation; for instance,
degradation by UV-light, hydrolysis, and sorption. According to the type of drug and
13 Pharmaceuticals: An Emerging Problem of Environment and Its Removal. . .
273