Causal Characteristics and Types of Evidence
The types of evidence and the characteristic of causation that they can represent are presented in Tables 5-3 and 5-4. Some types of evidence can support more than one characteristic, depending on how the study is designed.
The first set (Table 5-3) is based solely on evidence from the impaired site and associated comparison sites (i.e., sites that are part of the case). The second set (Table 5-4) uses knowledge gained from other studies to show that conditions at the impaired site could reasonably be expected to result in specific biological effects. Therefore, evidence for temporality and co-occurrence come only from the site. Evidence for coherence and sufficiency are more likely to come from other field and laboratory studies. Used together they make a stronger case that can help us identify probable causes of impairment in our environment.
Type of Evidence | Characteristic of Causal Relationships |
---|---|
Spatial/Temporal Co-occurrence | Co-occurrence |
Evidence of Exposure or Biological Mechanism | Interaction Alteration |
Causal Pathway | Antecedence |
Stressor-Response Relationships from the Field | Co-occurrence |
Manipulation of Exposure | Co-occurrence Temporality |
Laboratory Tests of Site Media | Sufficiency |
Temporal Sequence | Temporality |
Verified Prediction | Alteration |
Symptoms | Alteration |
Type of Evidence | Characteristic of Causal Relationships |
---|---|
Stressor-Response Relationships from Other Field Studies | Sufficiency |
Stressor-Response Relationships from Laboratory Studies | Sufficiency |
Stressor-Response Relationships from Ecological Simulation Models | Sufficiency |
Mechanistically Plausible Cause | Alteration |
Manipulation of Exposure at Other Sites | Sufficiency |
Analogous Stressors | Alteration |