# Presentation: 326697

## An EPA Sponsored Literature Review Database to Support Stressor Identification 

- Benjamin Jessup
- Cathy Cresswell
- Tetra Tech, Inc.

- Patricia Shaw-Allen, Ph.D.
- Bhagya Subramanian
- Susan Cormier, Ph.D.
- EPA,
- Office of Research and Development

## What is Stressor Identification?
Stressor Identification = Causal Analysis
Structured, consistent strategy for identifying the cause(s) of a biological impairment

Why perform Causal Analysis?

The Causal Analysis/Diagnosis Decision System (CADDIS) home to the Causal Analysis/Diagnosis LITerature database (CADLit)

	                     	Structure
			Data detail
			User interface and queries
			Current focus and future directions

**Stressor Identification = Causal Analysis**
**Structured, consistent strategy for identifying the cause(s) of a biological impairment**
**Why perform Causal Analysis?**
**The Causal Analysis/Diagnosis Decision System (CADDIS) **home to the Causal Analysis/Diagnosis LITerature database (CADLit)
**	****                     **	**Structure**
**	****	****	****Data detail**
**	****	****	****User interface and queries**
**	****	****	****Current focus and future directions**

- Overview

***The CADLit***

**Notes:**
Causal analysis attempts to identify those factors that are responsible for impairment.

## The Stressor Identification Strategy

- Logically eliminate causes when you can
- Diagnose causes when you can
- Use strength of evidence for the rest
- Do not claim proof of causation
- Identify the most likely cause
- Use a consistent process
- Document the evidence and inferences

**EPA Guidance in 2000**
**	****http://www.epa.gov/ost/biocriteria/stressors/stressorid.pdf**

**Notes:**
To convince skeptical stakeholders 
To increase a manager’s confidence that costly remedial or restoration efforts are targeted at factors that can truly improve biological condition. 
To identify causal relationships that are otherwise not immediately apparent.  
To prevent biases or lapses of logic that may not be apparent until a formal method is applied. 

“The first principle of science is that you must not fool yourself --and you are the easiest person to fool”
--Richard Feynman

Causation is one of the most difficult and controversial concepts in philosophy
Only one reliable method
Randomized, replicated, controlled experiment
Not available to us
But we all think we know how to do it
Hard wired to jump to conclusions
Creaking wood at night means intruder!
Causal analysis says thermal contraction

Elimination:
Cause is downstream of effect
Cause occurs after effect
Effect decreases with increasing cause
Cause occurs in reference streams as well as impaired
Effect persists after cause has been removed
Causal pathway is incomplete

## Why Causal Analysis?

***Causal Analysis***** uses biological assessment data to identify the cause(s) of impairment**
**In 2002, All States and several Tribes were using **_**biological assessments**_** for streams and small rivers.**
**Identified 1,440 waters with biological impairments**
**-****	**representing 30,499 river miles with unknown cause(s)
**TMDL Program escalates!  **
- -	TMDL lawsuits
- -	States need help:  What are the causes of observed biological impairment?

**Notes:**
Bioassessment
Biocriteria:  Clean Water Act
State Biological Criteria
What if criteria are not met?  TMDL!
TMDL requires identification of pollutants – what pollutants caused biological impairment?

When is causal analysis needed?
Implementing biological WQ standards:  TMDLs
Investigating fish kills
Contaminated sites
Interpreting biological monitoring results
Recovery plans for T&E species
Any other case of observed effects

History:
Risk Assessment
Ecological Risk Assessment
Prospective
Retrospective
Damage assessments, superfund:  What caused it?
Toxicity Identification and Evaluation (TIE)
Now, Stressor Identification (Guidance in 2000)

Alternatives to Association for Identifying Causes:
Deduction from theory
Our theories are not that good
Computational toxicology some day
Consensus
Stakeholder processes
Regulatory constraints
The cause is the one we can hammer

## Causal Analysis/Diagnosis Decision Information System (CADDIS)

**A web based ****decision support system ****providing information and guidance ****t****o assist State and Tribe investigators in identifying causes of biological impairments****.**

## What will CADDIS Contain?

- A web-based, step by step guide to Stressor Identification
- Worksheets
- Examples
- Links
- 3.	Analytical tools for users
- Regional associations
- Stressor-specific tolerance values
- Conceptual model library
- Web based model builder in the future
**and....**
**Database of empirical stressor-response studies**
**Sediments**
**Toxic metals**
**Other stressors**

***aka...The CADLit!***

## The Causal Analysis/Diagnosis LITerature database (CADLit)

- Stores source, stressor, and response information from scientific publications
- Summarizes the usefulness of each reviewed paper to SI
- Documents relationships between sources, stressors, and responses
- Allows investigators to query the database for relevant source, stressor, response, and location variables

## Criteria for Data Inclusion

- Must be ***useful for Causal Analysis**** *by* *supporting at least one of the following lines of evidence:
**Stressor-response** (thresholds or response curves),
**Association** (finding association *or failure *to find association consistently),
**Experiment** – recovery or failure to recover after removal of a stressor in a real habitat or a mesocosm,
- Description of **mechanism** of how exposures result in responses, or
**Specificity** of effects – evidence that an observed response can be used diagnostically

**Notes:**
Hill’s criteria:
Strength
Consistency
Specificity
Temporality
Biological Gradient
Plausibility
Coherence
Experiment
Analogy

## Plausible Stressor Response

**Low dissolved oxygen has been shown to cause mortality with fish in controlled studies.**
**DO levels at the site are at a concentration shown to cause mortality.**

**Plausible Stressor Response**

**Strength of Evidence **
**Considerations based on other situations or biological information**

**Notes:**
Association would be when there is no gradient, but the stressor is categorical:  either present or absent (e.g., dams)

## Experiment

**Controlled mesocosm  or field experiments demonstrate that the candidate cause can induce the observed effect**

**Strength of Evidence **
**Considerations based on other situations or biological information**

## Plausible Mechanism

**Given what is known about the biology, physics and chemistry of the stressor (low dissolved oxygen), the receiving environment, and the affected organism, it is plausible that the stressor caused the impairment and behavior of gulping air at the water surface.**

**Plausible Mechanism**

**Strength of Evidence **
**Considerations based on other situations or biological information**

**Notes:**
In CADLIT, mechanisms are checked when there is information regarding the stressor response pathway: 
How does the stressor act upon the receptor?

## Specificity

**Strength of Evidence **
**Considerations based on other situations or biological information**

**The impairment (jagged cut) observed in the fish can only occur from a boat propeller or other mechanical hazard.  Therefore, one of these stressors must be the actual cause.**

## Database Structure

- Relevant publications are complex, often reporting results
- from multiple study designs and many environmental
- stressor and non-stressor parameters

## Database Structure: Exposures

**Notes:**
The only reason for having multiple exposure sets in when there are multiple independent stressors.
We may note without transcribing data those parameters that were recorded in the paper but that were of marginal importance to the analysis.

## Database Structure: Responses

**Notes:**
Response types: assemblage response, behavior, toxicity, physiology, accumulation.
Response includes taxon or taxa group – a valuable search term for queries.
Response class details include stressor-response thresholds, effect levels, regression, or other description of the relationship.

## Data Entry

**Notes:**
Papers retrieved from ISI web of science searches.
Topical searches and forward and backward searches on known relevant papers.

## Response Details

## User Interface

**Effects **

**Cause****/****Stressor**

**Source****/ ****Land**** ****Use**

** ****All**** ****Keywords**** **

**Geographic**** ****Area**** **

**Search for Known Associations**
- Select specific term(s) from any category (or categories) for known associations

**Associations**

**Notes:**
User interface – under development

##  Source Query

## Query Output

**Notes:**
The output may include only a listing of citations or a summary of findings from each relevant paper.
Either the investigator will retrieve the papers and glean the information for themselves,
Or the information from CADLIT will suffice (importance of QC in reviewing papers).

## Strength of Evidence 

**Consistency of Association**

**Strength of Evidence **
**Considerations based on other situations or biological information**** **

**The impairment (dead fish) is observed together with the stressor (********) at different locations across the country.**

## Current CADLIT Focus

- Peer reviewed scientific publications
- Freshwater aquatic life
- Priority metals (As, Cd, Cr, Cu, Pb, Hg, Se, Zn)
- Clean sediments (Suspended and bedded)

**Future Directions**

- Include additional stressors in CADLit
- Include grey literature (as appropriate)
- Available through the CADDIS Website Proposed release: 2005 – 2006