so that the microcosm test is established as a practical ecosystem impact assessment
method, replacing the mesocosm test method. As microcosms are expected to be
highly correlated with natural ecosystems, it is assumed that more realistic estimates
of the NOEC may be obtained when compared with the current method (i.e., singlespecies evaluation). Currently, it remains difficult to omit test methods using algae,
crustaceans, and fish in ecological impact assessments of chemical substances, as
typified by the WET test. However, by using an ecosystem model with a food chain
and energy flow in parallel, it is possible to accumulate knowledge concerning the
decomposability and persistence of chemical substances, restoration of ecological
functions, and collapse. In other words, it is expected that the advantages of the
microcosm will be evaluated by establishing a method of quantifying and evaluating
ecosystem impacts. The WET test is a method by which toxicity, including multiple
effects, may be evaluated. It does not evaluate the toxicity of individual chemical
substances, but rather it targets waters that contain multiple chemical substances.
However, when species from different niches in the food chain are used in the assay,
it is a single-species test. It must be noted that a problem remains in that material
circulation, energy flow, and biological interactions, which are the basic elements of
an ecosystem, are not incorporated in the test method under these conditions. The
microcosm, which is a system of multiple coexisting species, evaluates the risk of
chemical substances at the ecosystem level. The safety factor obtained by this
method also differed from the conventional method, according to the correlation
between the mesocosm test and the microcosm test. With the accumulation of further
data, it will be possible to calculate realistic values of the PNOEC for natural
ecosystems.
Literature Cited
Suzuki M, Utsumi H. Bioassey –risk management of water environment. Tokyo: Kodansha
Scientific; 1998. 270pp.
The Japanese Society of Environmental Toxicology. Handbook of ecosystem assessment test
–environmental risk assessment of chemicals, Tokyo. Asakura SHoten; 2003. 349pp.
Urano K, Matsuda H. Principles and methods for ecosystem risk management. Tokyo: Ohmsha;
2007. 209pp.
Utsumi H, Nakamuro K. Bioassey and bio-informatics, fpr environmental assessment and
medicinal sciences. Tokyo: Kougaku-Tosho Publishers Ltd; 2011. 214pp.
Wakabayashi A. Chemicals and ecotoxicity, Tokyo. Japan Environmental Management Association for Industry; 2004. 486pp.
Yoshida K, Nakanishi J. Basic environmental risk analysis. Tokyo: Tokyotosho; 2006. 234pp.
166
K. Kakazu et al.
method, replacing the mesocosm test method. As microcosms are expected to be
highly correlated with natural ecosystems, it is assumed that more realistic estimates
of the NOEC may be obtained when compared with the current method (i.e., singlespecies evaluation). Currently, it remains difficult to omit test methods using algae,
crustaceans, and fish in ecological impact assessments of chemical substances, as
typified by the WET test. However, by using an ecosystem model with a food chain
and energy flow in parallel, it is possible to accumulate knowledge concerning the
decomposability and persistence of chemical substances, restoration of ecological
functions, and collapse. In other words, it is expected that the advantages of the
microcosm will be evaluated by establishing a method of quantifying and evaluating
ecosystem impacts. The WET test is a method by which toxicity, including multiple
effects, may be evaluated. It does not evaluate the toxicity of individual chemical
substances, but rather it targets waters that contain multiple chemical substances.
However, when species from different niches in the food chain are used in the assay,
it is a single-species test. It must be noted that a problem remains in that material
circulation, energy flow, and biological interactions, which are the basic elements of
an ecosystem, are not incorporated in the test method under these conditions. The
microcosm, which is a system of multiple coexisting species, evaluates the risk of
chemical substances at the ecosystem level. The safety factor obtained by this
method also differed from the conventional method, according to the correlation
between the mesocosm test and the microcosm test. With the accumulation of further
data, it will be possible to calculate realistic values of the PNOEC for natural
ecosystems.
Literature Cited
Suzuki M, Utsumi H. Bioassey –risk management of water environment. Tokyo: Kodansha
Scientific; 1998. 270pp.
The Japanese Society of Environmental Toxicology. Handbook of ecosystem assessment test
–environmental risk assessment of chemicals, Tokyo. Asakura SHoten; 2003. 349pp.
Urano K, Matsuda H. Principles and methods for ecosystem risk management. Tokyo: Ohmsha;
2007. 209pp.
Utsumi H, Nakamuro K. Bioassey and bio-informatics, fpr environmental assessment and
medicinal sciences. Tokyo: Kougaku-Tosho Publishers Ltd; 2011. 214pp.
Wakabayashi A. Chemicals and ecotoxicity, Tokyo. Japan Environmental Management Association for Industry; 2004. 486pp.
Yoshida K, Nakanishi J. Basic environmental risk analysis. Tokyo: Tokyotosho; 2006. 234pp.
166
K. Kakazu et al.