operations was already built (Ministry of the Environment, Environment study
synthesis promotion costs: FY2009–FY2011), and it was frequently used to perform
tests between facilities. The OECD examination guidelines progressed through the
ring tests, and the establishment of an OECD standard docimasy was planned. The
outcomes obtained from this investigation are listed below.
1. Screening test of chemical agents using the microcosm
The experimental test was advanced by screening 198 listed chemical substances into three groups, those that acted on animals, plants and algae, or
bacteria, according to differences in their mechanisms. As a result, the foundational information of an OECD test was provided because the microcosm test did
not depend on the classification of chemical substances as mentioned previously,
the sensitivity was higher than in a single-species test, and it was strongly
correlated with the mesocosm test.
2. Environmental impact assessment of chemical agents using the microcosm
For establishment as a practical ecosystem impact statement technique for the
mesocosm test method, the examination of widespread chemical substances was
promoted. A positive ion surfactant, TMAC (1000 mg/L); an environmental
hormone, nonylphenol (100 mg/L); a sterilizer, mancozeb (300 mg/L), the
weed killers, alachlor (1000 mg/L), linuron (0.1 mg/L), and fomesafen (30 mg/
L); and an insecticide, chlorpyrifos (500 μg/L), which were provided for microcosm examination (m-NOEC), were matched with published data, and most of
the 26 substances examined exhibited similar behaviors to those in the field
experiment (mesocosm test). It became clear that there was a strong association
between the microcosm and the mesocosm.
3. Analysis of the relationship between the microcosm test and the mesocosm test
As described in Chap. 8, the validity of the toxicity evaluation by the microcosm test was considered, and it was shown that 23 of 26 substances adhered to
the confidence interval of the regression line and the strength of the correlations
among the microcosm, experimental ecosystem (mesocosm), and the natural
ecosystem was demonstrated by the means of the m-NOEC and the NOEC of
the natural ecosystem. The lower limit of the confidence interval is also a straight
line obtained by dividing the mean of the natural ecosystem NOEC by the
uncertainty coefficient (coefficient of assessment ¼ 200) calculated in consideration of the differences in ecosystem sensitivity. Only the lower limit line is
required to determine the PNOEC of a natural ecosystem, and, if the point on the
correlation plot is greater than this (i.e., above the lower limit line), then it is
measured in the microcosm (PNOEC) obtained by dividing the NOEC by the
coefficient of assessment (200). With a value that is lower than that of the natural
ecosystem (mesocosm test) PNOEC, it can protect the natural ecosystem. Most
chemicals measured in this investigation fit into this range (i.e., above the lower
limit line). On the other hand, while substances exceeding the upper limit can
predict the PNOEC, the value is less than in natural ecosystem NOECs. Only
1 substance out of 26 fell above the upper limit line, revealing that precision is
high in the microcosm test, regardless of the chemical substance in question.
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R. Inamori et al.
synthesis promotion costs: FY2009–FY2011), and it was frequently used to perform
tests between facilities. The OECD examination guidelines progressed through the
ring tests, and the establishment of an OECD standard docimasy was planned. The
outcomes obtained from this investigation are listed below.
1. Screening test of chemical agents using the microcosm
The experimental test was advanced by screening 198 listed chemical substances into three groups, those that acted on animals, plants and algae, or
bacteria, according to differences in their mechanisms. As a result, the foundational information of an OECD test was provided because the microcosm test did
not depend on the classification of chemical substances as mentioned previously,
the sensitivity was higher than in a single-species test, and it was strongly
correlated with the mesocosm test.
2. Environmental impact assessment of chemical agents using the microcosm
For establishment as a practical ecosystem impact statement technique for the
mesocosm test method, the examination of widespread chemical substances was
promoted. A positive ion surfactant, TMAC (1000 mg/L); an environmental
hormone, nonylphenol (100 mg/L); a sterilizer, mancozeb (300 mg/L), the
weed killers, alachlor (1000 mg/L), linuron (0.1 mg/L), and fomesafen (30 mg/
L); and an insecticide, chlorpyrifos (500 μg/L), which were provided for microcosm examination (m-NOEC), were matched with published data, and most of
the 26 substances examined exhibited similar behaviors to those in the field
experiment (mesocosm test). It became clear that there was a strong association
between the microcosm and the mesocosm.
3. Analysis of the relationship between the microcosm test and the mesocosm test
As described in Chap. 8, the validity of the toxicity evaluation by the microcosm test was considered, and it was shown that 23 of 26 substances adhered to
the confidence interval of the regression line and the strength of the correlations
among the microcosm, experimental ecosystem (mesocosm), and the natural
ecosystem was demonstrated by the means of the m-NOEC and the NOEC of
the natural ecosystem. The lower limit of the confidence interval is also a straight
line obtained by dividing the mean of the natural ecosystem NOEC by the
uncertainty coefficient (coefficient of assessment ¼ 200) calculated in consideration of the differences in ecosystem sensitivity. Only the lower limit line is
required to determine the PNOEC of a natural ecosystem, and, if the point on the
correlation plot is greater than this (i.e., above the lower limit line), then it is
measured in the microcosm (PNOEC) obtained by dividing the NOEC by the
coefficient of assessment (200). With a value that is lower than that of the natural
ecosystem (mesocosm test) PNOEC, it can protect the natural ecosystem. Most
chemicals measured in this investigation fit into this range (i.e., above the lower
limit line). On the other hand, while substances exceeding the upper limit can
predict the PNOEC, the value is less than in natural ecosystem NOECs. Only
1 substance out of 26 fell above the upper limit line, revealing that precision is
high in the microcosm test, regardless of the chemical substance in question.
212
R. Inamori et al.