organisms (68.8, 71.9, and 7.5 mg DF L
À1 and 101.2, 342.2, and 22 mg IB L
À1 for
D. magna, S. subspicatus, and L. minor, respectively) (Table 2).
The acute effect of DF and IB was also studied by Nieto et al. [19] in the widely
distributed freshwater shrimp Atyaephyra desmarestii [74, 75]. Assays were realized
according to the US EPA Penaeid Acute Toxicity Test protocol (96 h assays), and
results obtained were used to calculate LC 50 for both compounds: 6.3 and
13.3 mg L
À1 , respectively, for DF and IB (Table 2). These results highlight once
again the higher toxicity of DF.
The acute toxicity data (LC 50 or EC 50 ) can be used by referring to the EU
Directive 93/67/EEC [76] to classify the substances in different risk classes:
“extremely toxic” to aquatic organisms (LC 50 or EC 50 < 0.1 mg L
À1 ), “very
toxic” (0.1–1 mg L
À1 ), “toxic” (1–10 mg L
À1 ), “harmful” (10–100 mg L
À1 ), and
“no toxic” (>100 mg L
À1 ). According to this criterion, both for naupliar stage of
T. battagliai and for A. desmarestii, DF and IB can be classified as toxic and harmful,
respectively. However, observing the LC 50 values reported in Table 2, we can see
that toxicity level varies from “no toxic” to “extremely toxic” for DF and from “no
toxic” to “harmful” for IB depending on the species considered (sensitivity, developmental stage, etc.). The LC 50 (or EC 50 ) values can be used to estimate the risk
associated with pharmaceuticals by the calculation of a risk quotient (RQ) using the
equation seen above: in line with the above, the risk associated with the exposure to
DF and IB will be different for different species. According to the classification
indicated in the EU TGD [9], the risk can be defined as low environmental risk when
0.01 < RQ 0.1, medium risk when 0.1 < RQ 1, and high risk when RQ > 1.
Equation (1) can be used to derive the environmental concentrations associated with
a low risk for aquatic organisms from the PNEC values. In Table 3, LC 50 obtained
for T. battagliai and A. desmarestii were used to calculate the PNEC values
(applying an assessment factor of 1,000 recommended for toxicity data obtained
from short-term assays and considered as a conservative and protective value, [9])
and successively to estimate the environmental concentrations of DF and IB associated with a low risk for both species (0.01 < RQ 0.1). A concentration range of
95–950 ng L
À1 for DF and 497–4,970 ng L
À1 for IB represents a low risk for the
copepod T. battagliai (no risk for environmental concentrations lower than 95 and
497 ng L
À1 for DF and IB, respectively). For the freshwater shrimp, the exposure to
DF in the range of 63–630 ng L
À1 or to IB in the range of 133–1,330 ng L
À1 would
be associated with a low risk for this species (no risk for environmental concentrations lower than 63 and 133 ng L
À1 for DF and IB, respectively).
Similarly, environmental concentrations associated with low or no risk can be
calculated for other organisms, particularly for the most sensitive species, extrapolating limit values below which the protection of aquatic organisms is guaranteed
(Table 4).
As indicated above, aquatic organisms are exposed to mixtures of chemicals that
can interact with each other producing greater effects than expected; therefore, the
risk assessment based on the effects of individual chemicals can significantly
underestimate the degree of risk. The acute effects of the mixture of DF and IB
were studied by Trombini et al. [21] and Nieto et al. [19] both on T. battagliai and
Ibuprofen and Diclofenac: Effects on Freshwater and Marine Aquatic Organisms –. . .
171
À1 and 101.2, 342.2, and 22 mg IB L
À1 for
D. magna, S. subspicatus, and L. minor, respectively) (Table 2).
The acute effect of DF and IB was also studied by Nieto et al. [19] in the widely
distributed freshwater shrimp Atyaephyra desmarestii [74, 75]. Assays were realized
according to the US EPA Penaeid Acute Toxicity Test protocol (96 h assays), and
results obtained were used to calculate LC 50 for both compounds: 6.3 and
13.3 mg L
À1 , respectively, for DF and IB (Table 2). These results highlight once
again the higher toxicity of DF.
The acute toxicity data (LC 50 or EC 50 ) can be used by referring to the EU
Directive 93/67/EEC [76] to classify the substances in different risk classes:
“extremely toxic” to aquatic organisms (LC 50 or EC 50 < 0.1 mg L
À1 ), “very
toxic” (0.1–1 mg L
À1 ), “toxic” (1–10 mg L
À1 ), “harmful” (10–100 mg L
À1 ), and
“no toxic” (>100 mg L
À1 ). According to this criterion, both for naupliar stage of
T. battagliai and for A. desmarestii, DF and IB can be classified as toxic and harmful,
respectively. However, observing the LC 50 values reported in Table 2, we can see
that toxicity level varies from “no toxic” to “extremely toxic” for DF and from “no
toxic” to “harmful” for IB depending on the species considered (sensitivity, developmental stage, etc.). The LC 50 (or EC 50 ) values can be used to estimate the risk
associated with pharmaceuticals by the calculation of a risk quotient (RQ) using the
equation seen above: in line with the above, the risk associated with the exposure to
DF and IB will be different for different species. According to the classification
indicated in the EU TGD [9], the risk can be defined as low environmental risk when
0.01 < RQ 0.1, medium risk when 0.1 < RQ 1, and high risk when RQ > 1.
Equation (1) can be used to derive the environmental concentrations associated with
a low risk for aquatic organisms from the PNEC values. In Table 3, LC 50 obtained
for T. battagliai and A. desmarestii were used to calculate the PNEC values
(applying an assessment factor of 1,000 recommended for toxicity data obtained
from short-term assays and considered as a conservative and protective value, [9])
and successively to estimate the environmental concentrations of DF and IB associated with a low risk for both species (0.01 < RQ 0.1). A concentration range of
95–950 ng L
À1 for DF and 497–4,970 ng L
À1 for IB represents a low risk for the
copepod T. battagliai (no risk for environmental concentrations lower than 95 and
497 ng L
À1 for DF and IB, respectively). For the freshwater shrimp, the exposure to
DF in the range of 63–630 ng L
À1 or to IB in the range of 133–1,330 ng L
À1 would
be associated with a low risk for this species (no risk for environmental concentrations lower than 63 and 133 ng L
À1 for DF and IB, respectively).
Similarly, environmental concentrations associated with low or no risk can be
calculated for other organisms, particularly for the most sensitive species, extrapolating limit values below which the protection of aquatic organisms is guaranteed
(Table 4).
As indicated above, aquatic organisms are exposed to mixtures of chemicals that
can interact with each other producing greater effects than expected; therefore, the
risk assessment based on the effects of individual chemicals can significantly
underestimate the degree of risk. The acute effects of the mixture of DF and IB
were studied by Trombini et al. [21] and Nieto et al. [19] both on T. battagliai and
Ibuprofen and Diclofenac: Effects on Freshwater and Marine Aquatic Organisms –. . .
171