Welcome! . . . to the April 2014

IRIS Bimonthly Public Science 

Discussion

December 2013
2

Today’s Attendance Is More Diverse Than Before
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About IRIS

IRIS assessments critically review the publicly available 

scientific studies on chemicals found in the environment to

 Identify adverse health effects

 Characterize exposure-response relationships

HAZARD 

IDENTIFICATION

Which effects are 

credibly 

associated with 

the agent?

DOSE-RESPONSE 

ASSESSMENT

Characterize exposureresponse relationships

Account for high-to-low-dose, 

animal-to-human, route-toroute, and other differences

EXPOSURE ASSESSMENT

How do people come in contact 

with the agent?

How much are they exposed to?

RISK 

CHARACTERIZATION

Integrate HAZARD, 

DOSE-RESPONSE, and 

EXPOSURE

RISK 

MANAGEMENT

Develop, analyze, 

compare 

options

Select appropriate 

LEGAL response

POLITICAL

SOCIAL

ECONOMIC

TECHNICAL
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IRIS Means Systematic Review

Identify Pertinent Studies

Evaluate Study Methods 

and Quality

Evaluate Weight of Evidence 

for Each Effect

Select Studies for Deriving 

Toxicity Values

Derive Toxicity Values
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IRIS Means Multi-level Comment and Peer Review

Identify Pertinent Studies

Evaluate Study Methods 

and Quality

Evaluate Weight of Evidence 

for Each Effect

Select Studies for Deriving 

Toxicity Values

Derive Toxicity Values
6

IRIS Means Public Engagement

Public Discussion on 

Literature Search, Evidence 

Tables, Key Issues

Public Discussion – EPA may revise 

draft assessment and charge in 

response to public comments

Public Discussion on 

Problem Formulation

Identify Pertinent Studies

Evaluate Study Methods 

and Quality

Evaluate Weight of Evidence 

for Each Effect

Select Studies for Deriving 

Toxicity Values

Derive Toxicity Values
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• General comments docket (NEW!)

• Assessment-specific dockets

• Public science discussions during steps 1 and 4

• Public science workshops on specific topics

Broadly attended meetings are useful for discussing 

science issues where there are multiple points of view

• Ad-hoc meetings with external stakeholders

There Are Now Multiple Ways to Engage with IRIS
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Purpose: to discuss key science issues

What are key science issues? . . . They may pertain to

 study methods or quality

 approaches to reconciling positive and negative results

 mode-of-action hypotheses

 alternative interpretations of the evidence

 scientific considerations to address in the upcoming 

draft assessment

Public Science Discussion
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For each assessment . . .

 Introduction by EPA assessment managers

 For each science issue . . .

– Opening remarks by registered discussants

– Continued discussion by all meeting attendees

 Open Forum on the assessment

General Open Forum at the end of the meeting

Agenda for Today’s Public Science Discussion
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Scoping

• Direct hazards and stressors

•Sources

•Environmental exposure pathways

•Individual intake pathways

•At-risk populations

• Direct adverse health outcomes

Problem formulation

• Hazard-identification methods

•Stressor-characterization methods

• Computational methods

• Uncertainty-characterization 

methods

•Intake and internal-dose models

• Dose-response models and 

methods

• Health-outcome measurements 

methods

Scoping and Problem Formulation: 

Advice from the NRC

Source: NRC 2009, Science and Decisions, boxes 3-1, 3-2
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Studies in laboratory animals

• Species and sex

• Dose, duration, route of 

exposure

• Health effects considered

• Relevance to human health 

effects of concern

Studies in humans

• Study population selection, potential for selection 

bias

• Study population characteristics, generalizability

• Exposure assessment, potential for information bias

• Outcome identification, potential for bias

• Appropriateness of analytic methods

• Potential for confounding

• Precision of effect estimates

• Availability of exposure metrics

1. Literature search to identify pertinent studies

2. Evidence tables to summarize study methods and results

3. Evaluate study methods and quality

Identifying and Selecting Studies: 

Advice from the NRC

Source: NRC 2011, Formaldehyde, pp 158-159
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1. Literature search – summarized by PRISMA diagram

2. Evidence tables – summarize study methods and results

3. Evaluation of study methods and quality

 Start with all pertinent, publicly available studies

 Exclude studies based on problem formulation 

(beginning with Cr6, just released)

 Exclude studies with fundamental flaws

 Focus on studies with most robust methods 

(approaches can be discussed today)

Identifying and Selecting Studies:

Current Thinking in IRIS
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April releases

 Literature search, evidence tables for Hexavalent Chromium 

(animal studies)

 Literature search, evidence tables for Inorganic Arsenic

 These will be discussed at the June 25-27 meeting

June releases

 Additional literature-search/evidence-table materials

 Problem formulation materials

 These will be discussed at the Sept 3-4 meeting

Future Public Science Discussions
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The Enhanced IRIS

Improved 

science

- Systematic review

- Toxicity values for all credible health hazards

- Strengthened peer review

Increased 

transparency

- Clear, concise, systematic assessments

- Opportunities for public engagement

Increased 

productivity

We must make the Enhanced IRIS work by 

completing more assessments in less time

IRIS will continue to evolve as we receive public 

input and peer review advice – Thank you!