# Presentation: 546023

## Notice: The views expressed here are those of the individual authors and may not necessarily reflect the views and policies of the United States Environmental Protection Agency (EPA).  Scientists in EPA have prepared the EPA sections, and those sections have been reviewed in accordance with EPA’s peer and administrative review policies and approved for presentation and publication.  The EPA contributed funding to the construction of this website but is not responsible for it's contents. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

**Notice: The views expressed here are those of the individual authors and may not necessarily reflect the views and policies of the United States Environmental Protection Agency (EPA).  Scientists in EPA have prepared the EPA sections, and those sections have been reviewed in accordance with EPA’s peer and administrative review policies and approved for presentation and publication.  The EPA contributed funding to the construction of this website but is not responsible for it's contents. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.**

## Exploring Connections Between Ecological Condition and Human Health:

**Exploring Connections Between Ecological Condition and Human Health:**
**County-Level Aggregation for Maryland**

**John F. Paul**
**National Health and Environmental Effects Research Laboratory**
**U.S. Environmental Protection Agency**
**Research Triangle Park, North Carolina 27711**

## Acknowledgements

**Steve Hedtke**
**Michael McDonald**
**Wayne Munns**
**Hillel Koren**
**Jim Heltshe**
**Allan Marcus**

## Presentation Outline

**Definitions**
**Working Null Hypothesis**
**Methods and datasets**
**Results**
**Next Steps**

**Presentation Outline**

## Context

**Public policy continues to evolve in response to new and complex social, economic, & environmental drivers.**
**Science needs to anticipate, understand, assess, and reduce risks to human health and our environment to support mission of Agency (protect human health and safeguard the environment)**

## Context (cont’d)

**Holistic approach to environmental problem solving**
**Future environmental problem solving requires new and creative approaches - out-of-the-box thinking and risk taking**

## Long-Term Perspective

**Provide the Agency with the information,**
**methods & models needed to make informed**
**selections among policy options, identify **
**emerging risks, & minimize unintended**
**consequences**

## Hypothetical Example: Unintended Consequence of Improved Ecological Conditions on Human Health Outcomes

**Hypothetical Example: ****Unintended Consequence of ****Improved Ecological Conditions on ****Human Health Outcomes**

- Driver

- Environmental
- Issue

- Unintended
- Consequence

- Policy

- environmental
- protection

- surface
- water
- quality

- increased
- riparian
- buffers

- Increased risk of
- Lyme disease &
- exposure to
- fecal pathogens

## Definition: Eco-Human Connectivity

**relationship between ecological systems and human health**

**more than exposure-response**
**link condition of ecological systems with human health**
**not necessarily cause-effect**

## Starting Point

**View humans and ecological systems as one overall interacting system**
**Some actions can affect both human health and condition of ecological systems**
**Web of causation exists**

## Web of Causation

## Web of Causation

**Driver **

## Background for Working Null Hypothesis

***Independence:***** two things are independent if the probability of either is the same whether or not the other occurs**
**If there are actions that can affect both human health and condition of ecological systems, then the appropriate indicators for human health and condition of ecological systems are not independent**

## Background for Working Hypothesis (cont’d)

***Conditional probability:***** probability of something occurring when it is known that something else has occurred**
**Quantitative measure of eco-human connectivity is an appropriately determined conditional probability**
**For example, probability of occurrence of human health outcome for specified condition of ecological system**
**Or more specifically, probability of higher than normal infant mortality for a county if more than half of streams in the county are impaired **

## Working Null Hypothesis 

**P ( Y ) = probability of Y (*****unconditional probability*****)**
**P ( Y | X ) = probability of Y if X occurs (*****conditional probability*****)**
**Eco-human connectivity null hypothesis:**
**P ( Y | X ) = P ( Y ) **
**or **
**conditional probability equals unconditional probability**

## Working Null Hypothesis (cont’d) 

**If eco-human connectivity exists, then first step is to disprove the null hypothesis**
**Remainder of presentation is focused on this**

## Data Bases Used for Analyses

**Maryland Biological Stream Survey**** (1995-97)**
**	******** ****Lattice sampling of 17 major drainage basins over three-years with probability design**
**	******** ****Approximately 300 stream segments sampled each year**
**	******** ****Use data for benthic IBI from 1995-97**
**Compressed Mortality Data****  - CDC Wonder (1978-1998)**
**	******** ****Under 1 year of age**
**	******** ****All races**
**	******** ****Both genders**
**	******** ****All causes of death**
**NOAA Coastal Assessment and Data Synthesis System**** (1990)**
**	******** ****Census of agriculture**
**	******** ****Fertilizer use and sales**
**	******** ****Pesticides**
**	******** ****Land Use /Land Cover **
**	******** ****Socioeconomics **

## Why Select Infant Mortality and Stream Condition?

**Infant mortality has long been considered a sensitive indicator of the impact of socioeconomic disparities on the health of populations (Gortmaker & Wise 1997)**
**Condition of bottom-dwelling communities in streams is integrative of environmental impacts occurring over recent time  **

## Why Maryland?

**Only state that has reported survey data for stream condition summarized at county level**

## Slide 20

## P ( Y | X > Xo) 

**P ( Y | X > Xo) **

## Application of Conditional Probability Approach

**Ability to identify undesired human health outcome level  exists, *****e.g.,***** infant mortality greater than 10 per 1000**
**Treat county as fundamental unit – equal weighting**

***Critical concept***
***50% of stream miles impaired in county***** **
**means**
***probability of observing impaired streams in county is 50%***

***Preliminaries***

## Conditional Probability Approach

**Given – **
**	****Y – undesired human health outcome - binary (infant mortality in county above 10 per 1000)**
**	****X – ecological condition – continuous (percent of stream miles in county with impaired benthos) **
**	****X****o**** – conditional value for ecological condition**
**Two-step approach to calculate P ( Y | X > X****o****) –**
**	****1. Identify subset of population with X > X****o**
**	****2. Determine fraction of subset with undesired outcome**
**Calculate P ( Y | X > X****o****) for all observed values of X**

## Slide 24

## Is the association real or fantasy?

**Is the association real or fantasy?**
**Answer by trying to disprove null hypothesis**

## Test null hypothesis for individual stream condition value

**Can’t use t-test, two sets tested are not independent**
**Result using bootstrap estimation:**
**If greater than 78% of stream miles in county are impaired there is less than 2% chance that value for probability of infant mortality exceeding 10/1000 could have occurred randomly**
**Look at entire range of values to determine when null hypothesis disproved – Bayesian model to account for uncertainty**

## Bayesian Model 

**Probability of infant mortality > 10/1000**

**Bayesian Model**** **
**(mean and 95% posterior intervals)**

## Md

**Md**

**Pa**

**WVa**

**Md: MBSS**
**Pa, WVA: EMAP-SW**

## Risk calculations for infant mortality in a county for fraction of stream miles in county with impaired benthos 

**Risk calculations for infant mortality in a county for fraction of stream miles in county with impaired benthos **
**(number of counties in each category)**

## Slide 30

## Where is this all going?

**Continue evaluation of eco-human connectivity for additional data sets**
**Interesting observations can lead to hypothesis generation**
**Useful for identification of gaps/needs/unidentified problems**
**Web of causation - Possible tool to help target management actions**
**Web of causation - Conceptual model for problem identification/formulation in risk assessment**
**Limitation: County is smallest level of aggregation for mortality data**

## Unhealthy Streams – Unhealthy Children

**Unhealthy Ecosystems – Unhealthy People**

**Healthy Ecosystems – Healthy People**

## THE END