Consultant's Report - Minnesota State Legislature

Pre-fertilization andpost-fertilization tests
These tests were designed to address effects of Cu treatments on fertilization rate.
In the pre-fertilization tests, addition of Cu solutions to eggs prior to fertilization
addressed treatment effects on gamete viability, fertilization processes and 0 to 24-h
development of larvae. In contrast, the post-fertilization tests enabled measurement of
treatment effects during 0 to 24-h development. Significant differences in sensitivity
between the pre-fertilization and post-fertilization tests were interpreted as treatment
effects upon gamete viability and fertilization processes. For post-fertilization tests, Cu
solutions were added 2: 15 min after sperm addition, to allow fertilization in the absence
of Cu treatments. Effects of Cu solutions on fertilization rate were assessed by recording
the number of living larvae as a fraction of eggs added per well. Moving larvae were
considered to be alive.
Pre-veliger tests
These tests addressed the effects of Cu treatments on 24-h-, 48-h- and 72-h-old
larvae. At the start of each test, the number of living pre-veligers was recorded and the
appropriate Cu spiking solution was added. At test termination, surviving larvae were
counted.
Data analyses
Data were analyzed using trimmed Spearman-Karber probit analysis to estimate
LCso and LC99 values and, when the model allowed, 95 % confidel}ce limits. Control
mortality was corrected using Abbott's correction. TRVs were considered significantly
different when 95 % confidence limits did not overlap. ToxCalc© software was used for
all analyses (Tidepool Scientific, McKinleyville, CA).
Results and Discussion
Results for LCso data are summarized in Table 2. LCso values are shown in bold
type, and 95 % confidence limits in parentheses where the model allowed this estimation.
All data are mg CulL.
Results from experiment 1 reveal that LCso data for Cutrine®-Ultra were similar in
all stages of larval development from post-fertilization to 72 h old, ranging from 0.008 to
0.013 mg CulL. These values were also similar to those for Cu as CUS04, which ranged
from 0.007 - 0.008 mg CulL. These findings suggest that, for these life stages, Cu is the
active toxic compound in Cutrine®-Ultra, and that Cutrine®-Ultra toxicity might be
predicted by Cu concentration alone. In contrast, Cutrine®-Ultra exhibited a significantly
higher toxicity in the pre-fertilized egg exposures than did Cu alone. This was confirmed
by the third experiment, which utilized lower exposure concentrations to enable a more
definitive estimate of LCso. Comparison of these data with those for Cu also indicates
that the toxicity of Cutrine®-Ultra to pre-fertilization stage eggs was higher than that
associated with Cu alone.
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