cost demands, they are required and performed only under specific and priority
situations. Additional requirements may also apply to specific areas such as pesticides, where ecotoxicity characterization is required for other important species such
as honey bees or birds.
27.4 Prospective Assessment: Ecotoxicity of Chemicals
The assessment of ecotoxicity is required and performed within two different
frameworks, i.e., prospective assessment (testing of individual chemicals or materials) and retrospective assessment (testing of contaminated natural samples).
Prospective approach relates mainly to the assessment of individual chemicals
that are brought to the market by industry. Various regulatory frameworks exist for
groups of chemicals with different use like industrial compounds (European Parliament and the Council of the European Union 2006, 2008), plant protection products—pesticides (US EPA 1996; European Parliament and the Council of the
European Union 2009), biocides (European Parliament and the Council of the
European Union 2012), or pharmaceuticals. Regulations impose variable requirements regarding ecotoxicity ranging from few simple laboratory assays for industrial
chemicals to high-tier field experiments for pesticides. It should be highlighted that
all the toxicity and ecotoxicity bioassays have primarily been developed and
designed for this purpose, i.e., standardized assessment of individual chemicals.
Chemical ecotoxicity should be tested in both aquatic and soil arrangements.
Aquatic set-up allows very good standardization of the testing media as well as good
homogenization and distribution of the chemical in the test system. The latter factors
are however more complicated for soil. Chemicals can either be externally added
(spiked) into “standard” natural soils with different properties, which can be commercially purchased (such as (LUFA 2018)), or tested in the artificial soil prepared
according to standardized protocol (OECD 1984, 2009, 2016a, b). However, as
recently shown on different artificial soils collected within the international laboratory ringtest, even the standard artificial soils greatly differ in their final composition,
which affected the results of the ecotoxicity tests of externally added toxicants by
orders of magnitude (Bielská et al. 2017; Hofman et al. 2014; Vašíčková et al. 2015).
Ecotoxicity testing of individual chemicals includes exposure of test organisms in
parallel to a negative control (blank) and to a series of chemical concentrations. After a
given exposure time, the endpoint of interest is evaluated (e.g., growth, lethality,
number of offspring, etc.), the effects are related to control (e.g., percentage of change),
and the ecotoxicological parameters are derived from a concentration–response curve
(Fig. 27.2) including typically concentration of a chemical causing 50% effect (lethal,
effective, inhibitory—LC50, EC50, IC50, respectively), no-observed-effect concentrations (NOEC), and lowest-observed-effect concentration (LOEC).
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L. Bláha and J. Hofman
situations. Additional requirements may also apply to specific areas such as pesticides, where ecotoxicity characterization is required for other important species such
as honey bees or birds.
27.4 Prospective Assessment: Ecotoxicity of Chemicals
The assessment of ecotoxicity is required and performed within two different
frameworks, i.e., prospective assessment (testing of individual chemicals or materials) and retrospective assessment (testing of contaminated natural samples).
Prospective approach relates mainly to the assessment of individual chemicals
that are brought to the market by industry. Various regulatory frameworks exist for
groups of chemicals with different use like industrial compounds (European Parliament and the Council of the European Union 2006, 2008), plant protection products—pesticides (US EPA 1996; European Parliament and the Council of the
European Union 2009), biocides (European Parliament and the Council of the
European Union 2012), or pharmaceuticals. Regulations impose variable requirements regarding ecotoxicity ranging from few simple laboratory assays for industrial
chemicals to high-tier field experiments for pesticides. It should be highlighted that
all the toxicity and ecotoxicity bioassays have primarily been developed and
designed for this purpose, i.e., standardized assessment of individual chemicals.
Chemical ecotoxicity should be tested in both aquatic and soil arrangements.
Aquatic set-up allows very good standardization of the testing media as well as good
homogenization and distribution of the chemical in the test system. The latter factors
are however more complicated for soil. Chemicals can either be externally added
(spiked) into “standard” natural soils with different properties, which can be commercially purchased (such as (LUFA 2018)), or tested in the artificial soil prepared
according to standardized protocol (OECD 1984, 2009, 2016a, b). However, as
recently shown on different artificial soils collected within the international laboratory ringtest, even the standard artificial soils greatly differ in their final composition,
which affected the results of the ecotoxicity tests of externally added toxicants by
orders of magnitude (Bielská et al. 2017; Hofman et al. 2014; Vašíčková et al. 2015).
Ecotoxicity testing of individual chemicals includes exposure of test organisms in
parallel to a negative control (blank) and to a series of chemical concentrations. After a
given exposure time, the endpoint of interest is evaluated (e.g., growth, lethality,
number of offspring, etc.), the effects are related to control (e.g., percentage of change),
and the ecotoxicological parameters are derived from a concentration–response curve
(Fig. 27.2) including typically concentration of a chemical causing 50% effect (lethal,
effective, inhibitory—LC50, EC50, IC50, respectively), no-observed-effect concentrations (NOEC), and lowest-observed-effect concentration (LOEC).
554
L. Bláha and J. Hofman