9.3 Abused Pharmaceuticals (Illicit Drugs) in Aqueous
Environment
Cocaine, amphetamine, opioid, lysergic acid diethylamide, hallucinogen and cannabinoid are common classes of abused drugs. They are often referred to as ‘hidden
drug’, and the users’ hidden activities have given rise to their purported widespread
and escalation. Until recently, limited information in the literature was known about
illicit drugs and whether they similarly exist as pharmaceuticals in the environment.
The emerging trends in the spread and usage of these drugs have prompted many
international agencies to conduct risks assessment to ascertain the levels of impacts
to the environment. The sewage treatment plants were identified as routes through
which the drugs enter the environment, while direct dumping of expired drugs by
end-users and drug manufacturing companies is another source.
Some drug users do divert prescription drugs for medical purposes in many ways
to supplement their personal nefarious activities. The continuing practice has
affected people, environment and societies in many ways as their active bioactive
metabolites are continuously being discharged through the sewage disposal (e.g. to
landfills, grassland, incineration and land reclamation) to the environment in complex mixtures of reactions that are very difficult to understand.
Table 9.5 therefore illustrates and compares the drug levels from different sewage
treatment locations so as to appreciate the distribution and potential threats as
reported in the literature. The observed degree of removal of drugs from the influent
and its relative concentrations were higher when compared to the effluent drug
concentrations. For example, 225 and 2307 ng L
À1 cocaine and benzoylecgonine
in 5 sewage treatment work influents in Spain were higher compared to 47 ng L
À1 of
cocaine concentrations in effluent. The benzoylecgonine relative concentration is
about 10 times higher in the influent compared to the effluent.
The urination and faeces are products of metabolism through which
unmetabolized drugs and associated metabolites get to the sewage systems. The
fluctuation pattern in the use of lavatory, periods of work and resident population
vary from individuals and locations which invariably would similarly affect the illicit
load pattern. Active researches are ongoing on the detection of abused drugs; their
fate through human metabolism and environmental degradation processes are
needed to fully understand their myriad of pathways and behaviour.
Human metabolism of drugs in the body is associated with the biotransformation
of drugs into metabolites with the unchanged parent drug being eliminated in the
body. A degree of metabolism has been associated with a number of parameters such
as ethnicity, gender, age, patient and the drug administration time.
The conjugation reaction occurs when polar molecules transfer metabolites such
as the glucuronic acid transfer to hydroxyls, phenols, thiols, carboxyls, hydroxyl
amino and amines groups (Mustapha 2013). The interests are the metabolites that
may pass to the sewage, retain in the STWs and pass on to the environment through
effluents or biosolids. The following are the metabolisms of major illicit drugs
detected in wastewaters.
284
A. O. Mustapha
Environment
Cocaine, amphetamine, opioid, lysergic acid diethylamide, hallucinogen and cannabinoid are common classes of abused drugs. They are often referred to as ‘hidden
drug’, and the users’ hidden activities have given rise to their purported widespread
and escalation. Until recently, limited information in the literature was known about
illicit drugs and whether they similarly exist as pharmaceuticals in the environment.
The emerging trends in the spread and usage of these drugs have prompted many
international agencies to conduct risks assessment to ascertain the levels of impacts
to the environment. The sewage treatment plants were identified as routes through
which the drugs enter the environment, while direct dumping of expired drugs by
end-users and drug manufacturing companies is another source.
Some drug users do divert prescription drugs for medical purposes in many ways
to supplement their personal nefarious activities. The continuing practice has
affected people, environment and societies in many ways as their active bioactive
metabolites are continuously being discharged through the sewage disposal (e.g. to
landfills, grassland, incineration and land reclamation) to the environment in complex mixtures of reactions that are very difficult to understand.
Table 9.5 therefore illustrates and compares the drug levels from different sewage
treatment locations so as to appreciate the distribution and potential threats as
reported in the literature. The observed degree of removal of drugs from the influent
and its relative concentrations were higher when compared to the effluent drug
concentrations. For example, 225 and 2307 ng L
À1 cocaine and benzoylecgonine
in 5 sewage treatment work influents in Spain were higher compared to 47 ng L
À1 of
cocaine concentrations in effluent. The benzoylecgonine relative concentration is
about 10 times higher in the influent compared to the effluent.
The urination and faeces are products of metabolism through which
unmetabolized drugs and associated metabolites get to the sewage systems. The
fluctuation pattern in the use of lavatory, periods of work and resident population
vary from individuals and locations which invariably would similarly affect the illicit
load pattern. Active researches are ongoing on the detection of abused drugs; their
fate through human metabolism and environmental degradation processes are
needed to fully understand their myriad of pathways and behaviour.
Human metabolism of drugs in the body is associated with the biotransformation
of drugs into metabolites with the unchanged parent drug being eliminated in the
body. A degree of metabolism has been associated with a number of parameters such
as ethnicity, gender, age, patient and the drug administration time.
The conjugation reaction occurs when polar molecules transfer metabolites such
as the glucuronic acid transfer to hydroxyls, phenols, thiols, carboxyls, hydroxyl
amino and amines groups (Mustapha 2013). The interests are the metabolites that
may pass to the sewage, retain in the STWs and pass on to the environment through
effluents or biosolids. The following are the metabolisms of major illicit drugs
detected in wastewaters.
284
A. O. Mustapha