a small tendency for removal by adsorption due to their pKa values [31]. However,
the relatively high ibuprofen sorption coefficient [21, 28] allows for its elimination
by this method and by biodegradation [26, 32]. Diclofenac is eliminated minimally
by adsorption and biodegradation [26, 28] although under certain conditions it can
be eliminated by photodegradation and biodegradation [21, 31].
NSAIDs that are not eliminated in treatment plants penetrate the environment in
their original form or as degradation products and accumulate in water sources in a
continuous process that can present a threat to humans and the ecosystem.
2.2 Toxic Effects of NSAIDs at Low Concentrations
There are few data on the toxic effects that low concentrations of NSAIDs produce
on human health, aquatic organisms, and ecosystems [21, 31]. Some authors assume
that their presence in the waters can have subtle effects of the normal biochemistry of
human beings and aquatic species since the latter is exposed to these pollutants
throughout their lives [12, 19, 21, 27, 31, 33, 34]. However, data concerning chronic
toxic effects in aquatic organisms, except for aspirin, diclofenac, and naproxen, are
still scarce. Diclofenac, for example, has been included in the list of products that
require surveillance by the European Union [4, 35] due to the harmful effects it
causes at low concentrations. Salicylic acid and naproxen affect reproduction of
algae and planktonic crustaceans at concentrations of 1.8 mgL
À1 and 330 μgL
À1 ,
respectively [31, 36, 37]. Diclofenac affects the kidneys and gills of rainbow trout
and salmonids at concentrations of 5 μgL
À1 [38, 39]. One thousand times higher
concentrations of diclofenac, naproxen, and ibuprofen have been found in fish
exposed to effluents from a treatment plant compared to fish in their natural habitat
[34]. The degradation products of naproxen and diclofenac are even more toxic than
the original compounds [36, 40].
The concentrations of NSAIDs found in drinking water in various countries
[14, 17, 18, 31, 33, 41] are of concern to researchers because effects that their
continuous intake can have in the long-term are unknown. The situation is aggravated in countries with poor infrastructure for water treatment since the concentrations of these products may be higher than reported [27]. There are mathematical risk
models that allow estimating or predicting the possible effects of these products on
animals and aquatic plants [27, 31], but it is necessary to accumulate data on
continuous exposure in different environments and times of the year in order to
accurately deduce the real risks both in humans and other species.
86
K. Isaac-Olivé et al.
the relatively high ibuprofen sorption coefficient [21, 28] allows for its elimination
by this method and by biodegradation [26, 32]. Diclofenac is eliminated minimally
by adsorption and biodegradation [26, 28] although under certain conditions it can
be eliminated by photodegradation and biodegradation [21, 31].
NSAIDs that are not eliminated in treatment plants penetrate the environment in
their original form or as degradation products and accumulate in water sources in a
continuous process that can present a threat to humans and the ecosystem.
2.2 Toxic Effects of NSAIDs at Low Concentrations
There are few data on the toxic effects that low concentrations of NSAIDs produce
on human health, aquatic organisms, and ecosystems [21, 31]. Some authors assume
that their presence in the waters can have subtle effects of the normal biochemistry of
human beings and aquatic species since the latter is exposed to these pollutants
throughout their lives [12, 19, 21, 27, 31, 33, 34]. However, data concerning chronic
toxic effects in aquatic organisms, except for aspirin, diclofenac, and naproxen, are
still scarce. Diclofenac, for example, has been included in the list of products that
require surveillance by the European Union [4, 35] due to the harmful effects it
causes at low concentrations. Salicylic acid and naproxen affect reproduction of
algae and planktonic crustaceans at concentrations of 1.8 mgL
À1 and 330 μgL
À1 ,
respectively [31, 36, 37]. Diclofenac affects the kidneys and gills of rainbow trout
and salmonids at concentrations of 5 μgL
À1 [38, 39]. One thousand times higher
concentrations of diclofenac, naproxen, and ibuprofen have been found in fish
exposed to effluents from a treatment plant compared to fish in their natural habitat
[34]. The degradation products of naproxen and diclofenac are even more toxic than
the original compounds [36, 40].
The concentrations of NSAIDs found in drinking water in various countries
[14, 17, 18, 31, 33, 41] are of concern to researchers because effects that their
continuous intake can have in the long-term are unknown. The situation is aggravated in countries with poor infrastructure for water treatment since the concentrations of these products may be higher than reported [27]. There are mathematical risk
models that allow estimating or predicting the possible effects of these products on
animals and aquatic plants [27, 31], but it is necessary to accumulate data on
continuous exposure in different environments and times of the year in order to
accurately deduce the real risks both in humans and other species.
86
K. Isaac-Olivé et al.