TCEQ/NUATRC Air Toxics Workshop: Session V – Human Health Effects Nathan Pechacek, M.S. Toxicology Section Texas Commission on Environmental Quality [email protected].

TCEQ/NUATRC Air Toxics Workshop:

Session V – Human Health Effects

Nathan Pechacek, M.S.

Toxicology Section

Texas Commission on Environmental Quality

[email protected]

512-239-1336

TCEQ Organization

Toxicology Section

Risk Assessment Paradigm

• Seminal 1983 report

• Risk Assessment Paradigm:– Hazard identification– Dose-response assessment– Exposure assessment– Risk characterization

Role of Risk Assessment

Q1. Do better exposure estimates yield stronger associations with

health effects?• Exposure is essential for assessing potential health

effects• Exposure assessment typically improves the closer

the exposure measurement is to the individual– Personal monitors, biomarkers of exposure

• TCEQ typically relies on estimates of ambient concentrations to assess potential health effects– Dispersion models used to predict ambient levels for air

permit reviews– Ambient monitors (e.g., fixed, mobile)

Various ways to estimate exposure to air toxics

VS. VS.

Do better exposure estimates yield stronger associations with

health effects?• TCEQ recognizes the limitations of using ambient

measurements to assess potential health effects– Data not adequate for full-fledged risk assessment– Shows where health risks could be higher compared to

other areas– Helps focus limited resources on areas with higher

concentrations of air toxics

• TCEQ is interested in better understanding the relationship between ambient and personal exposures– HEATS project

Do better exposure estimates yield stronger associations with

health effects?

• Houston Exposure to Air Toxics Study (HEATS)– EPA R6 grant awarded to the TCEQ– Joint project of TCEQ, UTSPH, & NUATRC

• 2-year study in Houston comparing ambient, indoor, & personal monitoring of air toxics– Fall 2005 to Summer 2007

Q1. Do better exposure estimates yield stronger associations with

health effects?

• Better exposure estimates lead to a better understanding of potential health effects

Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?

• TCEQ recognizes the importance of both acute and chronic health concerns in assessing air toxics

• TCEQ develops Effects Screening Levels (ESLs) to assess air toxics for both acute and chronic health concerns

Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?

• ESLs:– Guideline air concentrations– Acute and chronic effects– Tool to identify air concentrations that would

not be expected to cause health effects from those requiring more review

– Used to evaluate air permits and ambient monitoring data

Benzene Concentration in Air(parts per billion, ppb)

Short-Term Exposure Long-Term Exposure(less than 14 days) (months to years)

100,000,000

10,000,000

1,000,000

100,000

10,000

1,000

100

10

1

0.1

DrowzinessDizziness

Headache

LeukemiaEye Irritation

EPA Acceptable Cancer Risk RangeTCEQ long-term Screening Level

TCEQ short-term Screening Level

OSHA 15-minute Standard

OSHA 8-hour Standard

OSHA Action Level

BenzeneHealth Effects

andRegulatory

LevelsDeath

Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?• TCEQ develops ESLs for thousands of chemicals.

– Most states evaluate only a limited number of chemicals (100 or less).

• TCEQ develops short- and long-term ESLs– Most states only evaluate long-term health effects.

• Current long-term ESLs for non-cancer health effects are generally more stringent than the values used by other states.

• Current long-term ESLs for cancer health effects are generally less stringent than the values used by other states.

• .TCEQ has updated its ESL derivation procedure and is having it scientifically peer reviewed by an independent third party. This peer review will be completed by August, 2005.

Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?

• TCEQ has updated its ESL derivation procedure

• Procedure peer reviewed in June 2005 by a scientific panel appointed by an independent third party.

• Peer review will be completed by end of 2005.

• For more information:www.tceq.state.tx.us/implementation/tox/esl/peer_rev/PRmain.html

Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?• Both acute and chronic health concerns need to be

assessed for air toxics• Historically much of the emphasis has been on

chronic effects, particularly cancer• Other effects (e.g., chronic non-cancer effects,

acute effects) need to be addressed– ESLs have historically addressed acute & chronic

effects– New ESL derivation procedures further reflects this

position using the latest science

Q3. Do mortality, cancer, exacerbation of asthma, and other respiratory and

cardiovascular diseases correlate with exposure?

• Key question• Air toxics are a broad class of air pollutants

– Should avoid generalization, should specify particular air toxic

• More research is needed on air toxics– Not as extensively studied as other air pollutants such as

O3 and PM– Heavy reliance on occupational and/or animal studies

• Challenge in extrapolating these results to exposures levels of the general population

Q3. Do mortality, cancer, exacerbation of asthma, and other respiratory and

cardiovascular diseases correlate with exposure?

• Much needs to be learned to adequately address this question

Summary• Q1. Do better exposure estimates yield stronger associations with

health effects?– Better exposure estimates lead to a better understanding of potential

health effects

• Q2. What is the appropriate proportion of attention that should be given to chronic and acute health outcomes?– Both acute and chronic health concerns need to be assessed for air toxics

• Historical focus often on cancer• Other chronic effects as well as acute effects need more focus

• Q3. Do mortality, cancer, exacerbation of asthma, and other respiratory and cardiovascular diseases correlate with exposure?– More research is needed

Questions?