Little Scioto River, OH, USA Worksheet Example Stressor-Response Relationships from Laboratory Studies

Example Worksheet : Stressor-Response Relationships from Laboratory Studies	Little Scioto River, OH, USA
Step 4: Evaluate Data from Elsewhere
Candidate causes considered on this worksheet:	Metals

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:

Table W1-22. Comparison of stressor measurements with probable effect levels.
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.

Evidence Scoring Table:
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.	--

Table W1-23. Stressor-response (lab) scores for candidate causes.
Candidate Cause	Result	Score
Metals	Metals concentrations did not exceed PEL	-