and pesticides [189]. Therefore, they are a key organism in the terrestrial environment, and their presence reflects a healthy soil environment.
Furthermore, earthworms constitute 60–80% of the soil biomass [190], allowing
them to be the preferred organisms for identifying the level of contamination in the
soil and in the agro-ecosystem, therefore the contamination of the food chain. In
addition, they maintain an integral position being the basis of the food chain.
Moreover, wide ranges of PhACs are susceptible to be absorbed by earthworms.
Lipophilic and hydrophilic compounds could enter into the earthworm system due to
absorption on its skin and diffusion by means of the mucous skin membrane,
respectively [183, 191, 192].
Furthermore, earthworms are incredible metabolic machines given the presence
of numerous enzymatic processes that take place in their tissues. Recently,
vermicomposting, a biotechnological composting process, has shown that some
terrestrial worms are capable of transforming organic compounds into a less toxic
final product [187].
The quantification of the pharmaceutical products taken and accumulated in
earthworms is important not only for assessing the direct risk on earthworms
themselves, but it is also the first step to estimate the transfer of contamination
through the food chain to the best predators such as birds. For example, Spurgeon
and colleagues studied the potential risk of secondary poisoning of metals transferred to earthworms’ predators, such as birds, through food chain [193].
However, very few studies have been directed toward the extraction, detection,
and quantification of pharmaceutical products in earthworms (Table 7), which may
represent an important limitation for the assessment of environmental, ecotoxicological, and human health risk. Furthermore, these reported studies were addressed
for risk assessment rather than for method development and validation for analytical
purposes. Again, this type of complex biological matrix requires selective and clean
extraction to be analyzed with precision. According to our literature survey, only two
research groups have undertaken a study dedicated to the multiresidual extraction of
pharmaceutical products in earthworm tissues [20, 181], although in the next
paragraph we will discuss the different steps and conditions for the preparation,
extraction, cleaning, and analysis of the samples reported in the literature.
7.1 Sampling, Sample Preparation, and Extraction
For earthworm sampling from soil field, the International Organization for Standardization (ISO) has standardized a protocol for soil invertebrate (earthworms)
sampling (ISO, 2006). Briefly, the field should be distributed to several subplots,
then two holes (dimension of one hole: 25 Â 50 cm and 20 cm deep) are hand-sorted
in each subplot, and earthworms are forced out by pouring in the holes diluted
solution (0.5%) of formaldehyde. Collected earthworms are then transferred alive on
a moist tissue to the laboratory for analysis. This protocol was followed by [192]. On
the other hand, Kinney and coworkers [183] followed another sampling protocol,
Development of Methods for the Determination of PhACs in Soil/Earthworm/Crop. . .
471
Furthermore, earthworms constitute 60–80% of the soil biomass [190], allowing
them to be the preferred organisms for identifying the level of contamination in the
soil and in the agro-ecosystem, therefore the contamination of the food chain. In
addition, they maintain an integral position being the basis of the food chain.
Moreover, wide ranges of PhACs are susceptible to be absorbed by earthworms.
Lipophilic and hydrophilic compounds could enter into the earthworm system due to
absorption on its skin and diffusion by means of the mucous skin membrane,
respectively [183, 191, 192].
Furthermore, earthworms are incredible metabolic machines given the presence
of numerous enzymatic processes that take place in their tissues. Recently,
vermicomposting, a biotechnological composting process, has shown that some
terrestrial worms are capable of transforming organic compounds into a less toxic
final product [187].
The quantification of the pharmaceutical products taken and accumulated in
earthworms is important not only for assessing the direct risk on earthworms
themselves, but it is also the first step to estimate the transfer of contamination
through the food chain to the best predators such as birds. For example, Spurgeon
and colleagues studied the potential risk of secondary poisoning of metals transferred to earthworms’ predators, such as birds, through food chain [193].
However, very few studies have been directed toward the extraction, detection,
and quantification of pharmaceutical products in earthworms (Table 7), which may
represent an important limitation for the assessment of environmental, ecotoxicological, and human health risk. Furthermore, these reported studies were addressed
for risk assessment rather than for method development and validation for analytical
purposes. Again, this type of complex biological matrix requires selective and clean
extraction to be analyzed with precision. According to our literature survey, only two
research groups have undertaken a study dedicated to the multiresidual extraction of
pharmaceutical products in earthworm tissues [20, 181], although in the next
paragraph we will discuss the different steps and conditions for the preparation,
extraction, cleaning, and analysis of the samples reported in the literature.
7.1 Sampling, Sample Preparation, and Extraction
For earthworm sampling from soil field, the International Organization for Standardization (ISO) has standardized a protocol for soil invertebrate (earthworms)
sampling (ISO, 2006). Briefly, the field should be distributed to several subplots,
then two holes (dimension of one hole: 25 Â 50 cm and 20 cm deep) are hand-sorted
in each subplot, and earthworms are forced out by pouring in the holes diluted
solution (0.5%) of formaldehyde. Collected earthworms are then transferred alive on
a moist tissue to the laboratory for analysis. This protocol was followed by [192]. On
the other hand, Kinney and coworkers [183] followed another sampling protocol,
Development of Methods for the Determination of PhACs in Soil/Earthworm/Crop. . .
471