Examples of Criterion Derivation
129
Embryomortality occurred in <1 % of randomly sampled aquatic-bird
eggs.
Concentrations of selenium in whole-body samples of fish are <3 Ilg/g.
Teratogenic deformities occurred in 0% offish from ichthyoplankton
samples.
Concentrations of selenium in ichthyoplankton samples are <3 Ilg/g.
Evaluation: The residues present in the HU were equivalent to reference levels, and no reproductive effects were evident. Samples from a
variety of wetland and riverine habitats indicated the same pattern:
little bioaccumulation and no reproductive effects.
Conclusion: The criterion for chronic exposure should be raised by
50%, to a final value of 7.5 Ilg SelL.
Example 3: No Modification Necessary
The existing criterion is 5 Ilg SelL, and the following information is
available for the HU (Ilg Se/g concentrations are in dry weight):
Waterborne concentrations of selenium are 2-5 Ilg/L.
Concentrations of selenium in sediments are 1-4 Ilg/g.
Concentrations of selenium in aquatic food-chain organisms are 1--6 Ilg/g.
Concentrations of selenium in randomly sampled aquatic-bird eggs
are 2-8 Ilg/g.
Teratogenic deformities occurred in 0% of randomly sampled aquaticbird eggs.
Embryomortality occurred in <1 % of randomly sampled aquatic-bird
eggs.
Concentrations of selenium in whole-body samples of fish are 3-6
Ilg/ g.
Teratogenic deformities occurred in 0% offish from ichthyoplankton
samples.
Concentrations of selenium in ichthyoplankton samples are 3-8 Ilg/g.
Evaluation: Residues of selenium are at toxicity thresholds, but no reproductive effects are evident (the fraction of a percent of embryomortality
present is considered background level, not due to selenium).
Conclusion: No change to the criterion for chronic exposure is indicated,
but monitoring of bird and fish reproduction (ie, sampling for evidence of
teratogenesis and embryomortality) and associated selenium residues is
recommended.
129
Embryomortality occurred in <1 % of randomly sampled aquatic-bird
eggs.
Concentrations of selenium in whole-body samples of fish are <3 Ilg/g.
Teratogenic deformities occurred in 0% offish from ichthyoplankton
samples.
Concentrations of selenium in ichthyoplankton samples are <3 Ilg/g.
Evaluation: The residues present in the HU were equivalent to reference levels, and no reproductive effects were evident. Samples from a
variety of wetland and riverine habitats indicated the same pattern:
little bioaccumulation and no reproductive effects.
Conclusion: The criterion for chronic exposure should be raised by
50%, to a final value of 7.5 Ilg SelL.
Example 3: No Modification Necessary
The existing criterion is 5 Ilg SelL, and the following information is
available for the HU (Ilg Se/g concentrations are in dry weight):
Waterborne concentrations of selenium are 2-5 Ilg/L.
Concentrations of selenium in sediments are 1-4 Ilg/g.
Concentrations of selenium in aquatic food-chain organisms are 1--6 Ilg/g.
Concentrations of selenium in randomly sampled aquatic-bird eggs
are 2-8 Ilg/g.
Teratogenic deformities occurred in 0% of randomly sampled aquaticbird eggs.
Embryomortality occurred in <1 % of randomly sampled aquatic-bird
eggs.
Concentrations of selenium in whole-body samples of fish are 3-6
Ilg/ g.
Teratogenic deformities occurred in 0% offish from ichthyoplankton
samples.
Concentrations of selenium in ichthyoplankton samples are 3-8 Ilg/g.
Evaluation: Residues of selenium are at toxicity thresholds, but no reproductive effects are evident (the fraction of a percent of embryomortality
present is considered background level, not due to selenium).
Conclusion: No change to the criterion for chronic exposure is indicated,
but monitoring of bird and fish reproduction (ie, sampling for evidence of
teratogenesis and embryomortality) and associated selenium residues is
recommended.