Exposure Science: Protecting Us from Chemical, Physical, and

Biological Agents

www.isesweb.org

Organization of Presentation

• Description of Exposure Science• Exposure Science: Why does it Matter?• Examples of the Impacts of Exposure Science• Realizing the Promise of Exposure Science for the

21st Century

2

What Is Exposure Science?

• The bridge between the sources of chemical, physical and biological agents and human health– Provides crucial information to estimate real-life risks to

health and to identify the most effective ways to prevent and reduce these risks.

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Human Health Risk Assessment and Management

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Exposure Science: Why Does it Matter?

• Exposure information is crucial to protecting health• Exposure science is required to put hazard data into

perspective• Predictive exposure science is fundamental to

identifying emerging trends and preventing and reducing public health risks from environmental agents in the upcoming decades

• Supporting exposure science now will pay major dividends in the future

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Examples of the Impacts of Exposure Science

• Protecting ecosystems• Protecting people from physical agents• Protecting people from infectious agents• Protecting people from chemical agents

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http://www.nature.com/jes/webfocus/esdigests/index.html

Oil Spills and Fish Health: Exposing the Heart of the Matter

• Marine ecosystems fundamental to life, from single-cell organisms to humans, and to world economies

• These ecosystems have great resilience, but retain significant vulnerability to disturbances

• Major oil spills get major public, but limited scientific, attention• Multiple small oil spills occur almost daily with virtually no attention

– Stormwater runoff from streets, atmospheric “fall out” from motor vehicle emissions, spills of “bunker” fuel which powers large ships, etc.

– Such spills will increase with rising automobile ownership, coastal population growth, and expansion of container shipping

• Result: limited ability to predict effects of major spills and even less ability to determine whether more routine spills have chronic effects

Incardona et al., JESEE 21:3, 2011

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• Most people familiar with the immediate tragedy of oil-soaked birds and marine mammals after major spills

• We now know that our conventional wisdom is too limited, and many less visible impacts can occur (e.g., effects on hearts of fish embryos)

• Exposure science, coupled with toxicology, can lead the way in protecting and restoring marine ecosystems from spills

Oil Spills and Fish Health: Exposing the Heart of the Matter (2)

Head Region of Hatching-Stage Fish Embryos. Heart (Indicated by Arrows) shows adverse fluid accumulation after exposure.

Incardona et al., JESEE 21:3, 2011

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• Medical exposure of US population to ionizing radiation higher now (half of total in chart at right)

• Acute effects of high doses recognized early

• Chronic effects of lower doses now known to include cancer and non-cancer diseases

• Knowledge of dose-response crucial to protection

Better Radiation Exposure Estimation for the Japanese Atomic-Bomb Survivors Enables Us to Better Protect People from

Radiation Today

Sources of Radiation Exposure to the US Population

Cullings & Smith, JESEE 20:575, 2010

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Better Radiation Exposure Estimation for the Japanese Atomic-Bomb Survivors Enables Us to Better Protect People from

Radiation Today (2)

• Ongoing innovations in exposure assessments of Japanese atomic-bomb survivors continue to improve understanding of radiation health effects

• These survivors are still teaching us about dose-response effects, enabling scientists to identify harmful doses

• Helps to decide when protective actions are necessary, including– Workers at risk use protective equipment or limit time in radiation

areas– Radon measurements required for sale of houses in several

states– Newer generation of medical “x-ray” machines and techniques

delivers lower doses to patientsCullings & Smith, JESEE 20:575, 2010

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• Inhalation anthrax mortality higher than 90% if untreated and often deadly, even with antibiotic therapy and supportive care

• Course of infection has “point-of-no-return” after which all traditional treatments may fail

• Exposure science can reduce mortality

Anthrax: Modern Exposure Science Combats a Deadly Ancient Disease

Colored Scanning Electron Micrograph of Anthrax Bacteria (Bacillus anthracis)

Barr et al., JESEE 20:573, 2010

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Anthrax: Modern Exposure Science Combats a Deadly Ancient Disease (2)

• Exposure science advancements– Earlier diagnosis, even before symptoms, so treatment can begin

sooner– Analyzes many more blood samples/day so useful to blunt

epidemics or impacts of terrorist attacks– Can track infection even if antibiotic treatment started so easier to

prevent more infections– Quantifies course of infection so “point-of-no-return” can be

avoided– Quantifies efficacy of treatments so interventions work better

Barr et al., JESEE 20:573, 2010

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• Influenza virus has a history of killing millions of people

• In 2009, World Health Organization declared pandemic of 2009 H1N1 viruses– 57 million people worldwide

infected– 22 million people in US

infected and over 14,000 died

Exposure Science for Viral Diseases: 2009 H1N1 Pandemic Influenza Virus

Cox et al., JESEE 21:1, 2011

Scanning Electron Micrograph of H1N1 Influenza Virus

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Exposure Science for Viral Diseases: 2009 H1N1 Pandemic Influenza Virus (2)

• Exposure science taught us how to prevent transmission of influenza with simple measures (e.g., properly washing hands, coughing into one’s sleeve)

• More current exposure science enables earlier detection and identification of novel viruses, leading to – Development of more effective seasonal vaccines (vaccines now

are developed a year ahead of the flu season so prediction very important)

– Shortening of time for development of seasonal vaccine– Identification of most effective antiviral drugs– Reduced morbidity and mortality

Cox et al., JESEE 21:1, 2011

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• 1980 Superfund law directs EPA to clean up abandoned hazardous waste sites.

• Estimate: 1 in 4 Americans lives within 4 miles of Superfund site; approx. 10 million under 12 years old

Superfund: Is It Safe to go Home?

Lioy & Burke. JESEE 20:113, 2010

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Superfund: Is It Safe to go Home? (2)

• Superfund law does not effectively address exposure of residents near sites

• Conversely, exposure science results are essential to– Prioritize listed sites based upon those that pose the highest risks – Develop effective cleanup plan (e.g., water, air, house dust?)that

prevents future exposures– Determine whether the clean up actually has reduced the

potential exposures and risks sufficiently to go home safely• Exposure science results can be used to effectively protect

public health at lowest possible costLioy & Burke. JESEE 20:113, 2010

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Out of the Frying Pan and Out of the Fire

• Many laws and consumer demands lead to reduction or ban of chemicals, but their function is still needed

• Which is riskier: the “banned” chemical or the “replacement” chemical?

• We often know more about the banned chemical• Exposure science indispensable to avoid unwanted

exposures to replacement chemicals– We may go out of the frying pan, but we need to stay out of the

fire.

LaKind & Birnbaum JESEE 20:113, 2010

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Out of the Frying Pan and Out of the Fire (2)

• Flame retardants reduce fire incidence and severity

• One class of retardants (PBDE) was a replacement chemical in the 1970’s and widely used until unexpected exposure occurred, resulting in bans and voluntary phase-outs

• Exposure to replacements for PBDEs now occurring

• Need exposure science to be proactive when evaluating replacements to avoid unexpected exposures N

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Dramatic increase in PBDE flame retardants in breast milk of Swedish

women

LaKind & Birnbaum JESEE 20:113, 2010

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• Exposure science breakthrough in 1990’s: recognition by policy makers of unique exposures and vulnerabilities of fetuses, infants, and children to many chemicals

• Result: new laws and policies (e.g., Food Quality Protection Act focuses on protecting children)

Protecting Children from Pesticides and Other Toxic Chemicals

Boys Bathing in Recycled Pesticide Drum

Landrigan & Goldman, JESEE, 21:117, 2011

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Protecting Children from Pesticides and Other Toxic Chemicals (2)

• Pesticides in the Diets of Infants and Children (NRC, 1993)

– Children have greater exposures than adults on body weight basis (e.g., 1-yr old drinks 21 times more apple juice)

– Children’s metabolic pathways immature (e.g., can’t detoxify as much of some chemicals)

– Children have rapid growth and development, resulting in windows of vulnerability (e.g., brain injury from methylmercury)

– Children have more time to develop chronic diseases related to harmful exposures (e.g., early exposure can lead to adult onset)

Landrigan & Goldman, JESEE, 21:117, 2011

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• Children breath, eat, and drink proportionally more than adults, especially early in life

• Age-related differences in behavior (e.g. hand-to-mouth activity) impact exposure

• Toxicological sensitivity varies by age (from conception up) – thus, important to identify and account for “windows of susceptibility”

• U.S. EPA incorporating lifestage susceptibility into its risk assessments and policies

Protecting Children from Environmental Risks Throughout Each Stage of their Childhood

Total water ingestion (all sources), 95th percentile

Firestone JESEE 20:227, 2010

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Protecting Children from Environmental Risks Throughout Each Stage of their Childhood (2)

• U.S. EPA created standard set of 10 post-birth childhood age groups to account for lifestage differences when assessing and monitoring exposure to environmental toxicants

• U.S. EPA also has developed a complementary set of post-birth childhood age groups based on toxicological sensitivity to carcinogens which act via mutagenicity

• Already impacting risk assessments

Firestone JESEE 20:227, 2010

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Turn wishes into reality: Begin a new era of chemical management, with crucial support from exposure science:

• Modernize US Toxic Substance Control Act (TSCA) that regulates potentially toxic chemicals, by having more exposure and effects information

• Modify chemicals by design to be less toxic and less persistent in environment

Ensuring the Safety of Chemicals

Anastas et al., JESEE 20:395, 2010

“Wish I could always keep their environment safe!”

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Ensuring the Safety of Chemicals (2)• Over 10,000 chemicals currently in use, with more being

added each day– Older chemical-by-chemical approach to safety inadequate– Need sustainable approach to achieve safety while reaping

benefits of chemicals• Exposure science fundamental to

– Manage risks by creative design– Holistic understanding of use to prevent unintended consequences – Predict risk before it occurs– Empower people to make educated personal decisions

Anastas et al., JESEE 20:395, 2010

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MTBE: a Poster Child for Exposure Assessment as Central to Effective TSCA Reform

• U.S. Toxic Substances Control Act (TSCA) being revised by Congress to be more health-protective

• Advanced assessment of all major exposure pathways vital to improving TSCA

• Recent history of MTBE (an oxygenated fuel additive intended to reduce exposures to carbon monoxide and ozone) demonstrates need for exposure science

Goldstein, JESEE 20:229, 2010

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• MTBE legally required based on very poorly founded assumptions about health benefits

• 100 million Americans exposed before adequate knowledge of exposure and heath effects available

• MTBE leaked from tanks, contaminating drinking water, with economic & potential health impacts

• Problems could have been avoided if exposure predictions acted upon before wide use

MTBE: a Poster Child for Exposure Assessment as Central to Effective TSCA Reform (2)

Leaking Underground Fuel Storage Tank

Goldstein, JESEE 20:229, 2010

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• Airborne particulate matter (PM) causes morbidity and mortality

• U.S. EPA sets health-protective Nat’l Ambient Air Quality Standards (NAAQS) for PM by mass, with aerodynamic diameter cut points of 10µm and 2.5µm, based on both different chemical components and regional lung deposition

• Exposure science crucial to bases for these NAAQS

Targeting the Components Most Responsible for Airborne Particulate Matter Health Risks

Regional Respiratory Tract Deposition of Particles

Lippmann JESEE 20:117, 2010

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Targeting the Components Most Responsible for Airborne Particulate Matter Health Risks (2)

• Exposure science shows coarse thoracic PM (›2.5; ‹10µm) chemistry and sources different from fine PM (‹2.5µm)

• Toxicity also differs as a result of sites of deposition • Next generation of PM NAAQS needs to better

account for toxic components, not just mass by size• Application of exposure science fundamental to the

adoption of more efficient PM NAAQSLippmann JESEE 20:117, 2010

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• Science indicates there is no risk-free level of exposure to second-hand smoke (SHS) (US DHHS, 2006, Surgeon General Rpt)

• Exposure science basic to develop and implement smoke-free legislation around the world (e.g., graphic)

The Smoking Gun: Working to Eliminate Tobacco Smoke Exposure

Breysse & Navas-Acien, JESEE 20:397, 2010

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The Smoking Gun: Working to Eliminate Tobacco Smoke Exposure (2)

• Exposure science shows:– Locations (e.g., restaurants, bars, casinos) with elevated

SHS levels, providing guidance for behavior and laws– Mechanical ventilation systems and separate

nonsmoking sections in public places are insufficient to protect non-smokers

– Personal exposures of the general populace and specific groups, driving policies/laws and allowing evaluation of efficacy of or compliance with exposure reduction actions

Breysse & Navas-Acien, JESEE 20:397, 2010

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• Inhaled asbestos fibers can cause serious diseases (e.g., mesothelioma, lung cancer, asbestosis)

• In the mid 1900’s, not understanding and acting upon exposures early enough to intervene led to mortality of workers and diseases in their families

• Exposure science enables us to avoid repeating this history

Exposure Science Can Increase Protection of Workers and their Families from Exposure to Asbestos and Inform on the Effects of

Other Elongate Mineral Particles

Asbestos Bodies in a Human Lung

Bar= 20µm

Howard & Middendorf, JESEE 20:487, 2010

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Exposure Science Can Increase Protection of Workers and their Families from Exposure to Asbestos and Inform on the Effects of

Other Elongate Mineral Particles (2)

• Impacts of prior exposures continues– 77 asbestosis deaths in 1968 and 1,493 in 2000

• Exposure science warned of – Secondhand exposure of family contacts of asbestos workers – Public risks of exposures during asbestos removal efforts

• Exposure science needed to understand risks from modern-day types of occupational exposures

• New concerns over “elongate mineral particles” that share some asbestos properties– Present an opportunity to use exposure science to avoid the

mistakes of the past with asbestosHoward & Middendorf, JESEE 20:487, 2010

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Getting the Lead Out: Important Exposure Science Contributions

• Lead has adverse health effects at all ages for most organ systems, but greatest concern over developing nervous system of fetuses, infants, and young children

• This led to several successful national and international regulatory actions to reduce lead exposure based on exposure science, especially knowledge of – Exposure pathways and sources– Computer modeling of relationships between external exposures

and internal lead burdens

Grant, JESEE 20:577, 2010

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• Dramatic decrease in children’s blood lead initially due to phase- out of leaded gasoline in U.S.

• Later decreases due to acting on knowledge of pathways of exposure from other sources (leaded house paint, house dust, drinking water from leaded plumbing, food, etc.)

• As “safe” levels of lead decrease, continued vigilance using exposure science needed for continued reductions from additional and new sources (e.g., computer disposal, artificial turf, toys)

Getting the Lead Out: Important Exposure Science Contributions (2)

Percentage of children 1-5 years old in the U.S. population with elevated

blood lead levels

Grant, JESEE 20:577, 2010

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• Dramatic decreases (99% since 1970) in emissions counterbalanced by dramatic increase (170% since 1970) in vehicle miles traveled (VMT)

• Emissions major regulatory target to reduce ambient air health risks by reducing exposures

• But, understanding exposures to emissions very complex (emissions, VMT, air fate & transformation, proximity to traffic)

Vehicle Emissions: Progress and Challenges

U.S. Highway Vehicle Fleet Emissions Reductions since 1970

Sawyer, JESEE 20:489, 2010

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Vehicle Emissions: Progress and Challenges (2)

• Major challenges remain– Electric-drive (incl. hybrids) will help, but not a lot– “High-emitters” among the fleet – Heavy-duty vehicles have slower turnover and less emissions

regulations– As on-road emissions decrease, proportion of non-road mobile sources

increasing• Ozone and particulate matter (<2.5µm) still health concerns• Must know more about quantitative relationship of vehicle

emissions to actual exposure (by mass, number, chemistry & size) so regulations more effective

Sawyer, JESEE 20:489, 2010

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REALIZING THE PROMISE OF EXPOSURE SCIENCE FOR THE

21ST CENTURY REQUIRES INNOVATION AND

TRANSFORMATION OF EXPOSURE SCIENCE

Hubal et al., JESEE 21:119, 2011

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• Exposure science is a bedrock for protection of public health

• It fundamentally informs decisions for– Smart and sustainable

design– Prevention and mitigation of

adverse exposures – Health protection

The Promise of Exposure Science

Hubal et al., JESEE 21:119, 2011

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Future Challenges for Exposure Science

• Sustainability: Improve the health of individuals and communities today without compromising the health and welfare of future generations

• Risk analysis: Incorporate exposure science more effectively and efficiently into decisions

• Prevention: Shift from treatment to prevention of diseases through improved understanding of the role of environmental factors in etiology of disease

Hubal et al., JESEE 21:119, 2011

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Realizing the Promise Requires a Fundamental Cultural Shift Towards:

• Trans-disciplinary collaborations that provide linkages between exposure and health sciences

• A suite of innovative scientifically based tools and approaches to support public health decisions

• Holistic approaches to policy making • Commitment of resources to trans-disciplinary long-

term research and training

Hubal et al., JESEE 21:119, 2011

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MORE INFORMATION

• The Digests which formed the foundation for this presentation are available for free download at:– http://

www.nature.com/jes/webfocus/esdigests/index.html• Please visit www.isesweb.org for more information.

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SCIENCE FOR BETTER ENVIRONMENTAL HEALTH

This presentation and all articles cited from Journal of Exposure Science and Environmental Epidemiology (JESEE) are available for

free at www.isesweb.org; for articles click on Exposure Digests