diclofenac, fluoxetine and orlistat), and found that L. terrestris had lower uptake rate
constants through the skin (0.12–1.35 mL g
À1 day
À1 ) than E. fetida (1.48–4.46 mL g
À1 day
À1 ). The variation in the cuticle thickness between both species
could explain this marked difference in the API uptake rates [74], although contribution of other potential variables linked to experimental procedures (temperature of
incubation, soil pH, feeding habit of earthworms) should not be excluded. Indeed,
bioconcentration factors and uptake rate constants of APIs largely vary with the type
of soil [77].
4 Pharmaceutical Toxicity in Earthworms
There is a huge body of literature dealing with the impact of APIs on soil microorganisms [19, 78]. Alterations in microbial community structure and microbial
activity as well as emergence of antibiotic-resistant microorganisms are frequently
detected in soil receiving APIs [79, 80]. However, toxicity of these substances on
soil macrofauna is still scarce. Most data are obtained from laboratory incubation
studies (standardised toxicity testing), which being important in a regulatory context
for API marketing authorization [81], the outcomes provide limited information
about the real impact on soil macrofauna in an ecological context. For example, the
European Medicines Agency (EMA) guidelines recommend that assessment of API
adverse effects on terrestrial ecosystems should follow the standardised acute toxicity tests issued by the Organization for Economic Co-operation and Development
(OECD), such as OECD 207 [82] and OECD 222 [83], or the International Organization for Standardization (ISO), such as ISO 11268-1 [84], ISO 11268-2 [85] and
ISO 17512-1 [86]. The recommended earthworm species in all these tests are Eisenia
fetida and E. andrei. These two species display a set of advantages for running
standardised toxicity testing such as the high reproduction rate, the ease of measuring the toxicity endpoints (e.g. mortality, body mass change, reproduction rate,
behaviour), the low cost of maintenance in laboratory conditions and the availability
of individuals from local suppliers (e.g. fishing stores, vermiculture centres).
Toxicity testing has revealed that Eisenia species tolerate API-contaminated soils
compared to other soil organisms. For example, E. fetida was used in a standardised
multi-test study to identify the ecological risk assessment of the antiparasitic ivermectin [87]. The earthworm was less sensitive to ivermectin with no mortality
recorded after 28 days of exposure to soil spiked with 0.47–5.71 mg/kg dry soil
respect to collembolan and predatory mites. Similarly, the acute toxicity of fluazuron
(an insect growth regulator used to control ticks) was evaluated using E. andrei and
Folsomia candida. The acaricide was lethal to earthworms at high concentrations
(14d-LC 50 ¼ 111.3 mg/kg dry soil), reduced its reproduction rate (50% decrease
respect to controls) at concentrations !20 mg/kg, and the animals avoided soils
contaminated with !3.0 mg/kg fluazuron [88]. Likewise, the earthworms were also
less sensitive to fluazuron than collembolans. Eisenia andrei and F. candida were
also used for testing the acute toxicity of the veterinary pharmaceuticals nicarbazin
348
J. C. Sanchez-Hernandez
constants through the skin (0.12–1.35 mL g
À1 day
À1 ) than E. fetida (1.48–4.46 mL g
À1 day
À1 ). The variation in the cuticle thickness between both species
could explain this marked difference in the API uptake rates [74], although contribution of other potential variables linked to experimental procedures (temperature of
incubation, soil pH, feeding habit of earthworms) should not be excluded. Indeed,
bioconcentration factors and uptake rate constants of APIs largely vary with the type
of soil [77].
4 Pharmaceutical Toxicity in Earthworms
There is a huge body of literature dealing with the impact of APIs on soil microorganisms [19, 78]. Alterations in microbial community structure and microbial
activity as well as emergence of antibiotic-resistant microorganisms are frequently
detected in soil receiving APIs [79, 80]. However, toxicity of these substances on
soil macrofauna is still scarce. Most data are obtained from laboratory incubation
studies (standardised toxicity testing), which being important in a regulatory context
for API marketing authorization [81], the outcomes provide limited information
about the real impact on soil macrofauna in an ecological context. For example, the
European Medicines Agency (EMA) guidelines recommend that assessment of API
adverse effects on terrestrial ecosystems should follow the standardised acute toxicity tests issued by the Organization for Economic Co-operation and Development
(OECD), such as OECD 207 [82] and OECD 222 [83], or the International Organization for Standardization (ISO), such as ISO 11268-1 [84], ISO 11268-2 [85] and
ISO 17512-1 [86]. The recommended earthworm species in all these tests are Eisenia
fetida and E. andrei. These two species display a set of advantages for running
standardised toxicity testing such as the high reproduction rate, the ease of measuring the toxicity endpoints (e.g. mortality, body mass change, reproduction rate,
behaviour), the low cost of maintenance in laboratory conditions and the availability
of individuals from local suppliers (e.g. fishing stores, vermiculture centres).
Toxicity testing has revealed that Eisenia species tolerate API-contaminated soils
compared to other soil organisms. For example, E. fetida was used in a standardised
multi-test study to identify the ecological risk assessment of the antiparasitic ivermectin [87]. The earthworm was less sensitive to ivermectin with no mortality
recorded after 28 days of exposure to soil spiked with 0.47–5.71 mg/kg dry soil
respect to collembolan and predatory mites. Similarly, the acute toxicity of fluazuron
(an insect growth regulator used to control ticks) was evaluated using E. andrei and
Folsomia candida. The acaricide was lethal to earthworms at high concentrations
(14d-LC 50 ¼ 111.3 mg/kg dry soil), reduced its reproduction rate (50% decrease
respect to controls) at concentrations !20 mg/kg, and the animals avoided soils
contaminated with !3.0 mg/kg fluazuron [88]. Likewise, the earthworms were also
less sensitive to fluazuron than collembolans. Eisenia andrei and F. candida were
also used for testing the acute toxicity of the veterinary pharmaceuticals nicarbazin
348
J. C. Sanchez-Hernandez