CADDIS Volume 3: Examples & Applications
Worksheets: Little Scioto River, OH
Mechanistically Plausible Cause
Does a plausible mechanism exist for increased metals to cause the observed effects?
|Increased relative weight||No known mechanism|
|Increased DELT||Metals cause fin erosion and lesions. PB, Zn, and Cu cause deformities||1,2,3|
|Decreased percent mayflies||Metals cause lethal and sublethal effects on invertebrates||4,5|
Decreased percent mayflies and increased DELT can be linked to metals contamination. No plausible mechanism is known by which increased metals leads to increased relative weight.
|A plausible mechanism exists.||This finding somewhat supports the case for the candidate cause, but is not strongly supportive because levels of the agent may not be sufficient to cause the observed effect.||+|
|No mechanism is known.||This finding neither supports nor weakens the cause for the candidate cause.||0|
|The candidate cause is mechanistically implausible.||This finding strongly weakens the case for the candidate cause, but is not convincing because the mechanism could be unknown.||--|
|Candidate Cause||Specific Effects||Result||Score|
|Metals||Increased relative weight||Implausible: no known mechanisms||--|
|Decreased percent mayflies||Plausible||+|