CADDIS Volume 3: Examples & Applications
Worksheets: Little Scioto River, OH
Stressor-Response Relationships from Laboratory Studies
Do observed concentrations of metals exceed probable effect levels determined from laboratory studies?
Data
Fine-grained sediments were collected in the upper 15 cm of bottom material with decontaminated steel scoops. Samples were analyzed for metals. Concentrations of toxics were compared to sediment screening values, expressed as probable effect levels, above which toxicity to the test animal Hyallela azteca have been found to occur frequently.
Analysis
| Candidate Cause | Measurement | Observed value | Probable effect level | Exceedance? |
|---|---|---|---|---|
| Metals (mg/kg) |
Cr | 13.6 | 119.4 | No |
| Cu | 17.2 | 101.2 | No | |
| Pb | 19.2 | 81.7 | No | |
| Zn | 79 | 544 | No |
Discussion
None of the measured metals exceeded probable effect levels.
| Finding | Interpretation | Score |
|---|---|---|
| The observed relationship between exposure and effects in the case agrees quantitatively with stressor-response relationships in controlled laboratory experiments. | This finding strongly supports the case for the candidate cause, but is not convincing because the correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and the laboratory. | ++ |
| The observed relationship between exposure and effects in the case agrees qualitatively with stressor-response relationships in controlled laboratory experiments. | This finding somewhat supports the case for the candidate cause, but is not strongly supportive because the correspondence is only qualitative, and the degree of correspondence could be coincidental due to confounding or differences in organisms or conditions between the case and the laboratory. | + |
| The agreement between the observed relationship between exposure and effects in the case and stressor-response relationships in controlled laboratory experiments is ambiguous. | This finding neither supports nor weakens the case for the candidate cause. | 0 |
| The observed relationship between exposure and effects in the case does not agree with stressor-response relationships in controlled laboratory experiments. | This finding somewhat weakens the case for the candidate cause, but is not strongly weakening because there may be differences organisms or conditions between the case and the laboratory. | - |
| The observed relationship between exposure and effects in the case does not even qualitatively agree with stressor-response relationships in controlled laboratory experiments, or the quantitative differences are very large. | This finding strongly weakens the case for the candidate cause, but is not convincing because there may be substantial and consistent differences in organisms or conditions between the case and the laboratory. | -- |
| Candidate Cause | Result | Score |
|---|---|---|
| Metals | Metals concentrations did not exceed PEL | - |