Estimating risk from ambient concentrations of acrolein across the United States.
BACKGROUND
Estimated ambient concentrations of acrolein, a hazardous air pollutant, are greater than the U.S. Environmental Protection Agency (EPA) reference concentration throughout the United States, making it a concern for human health. However, there is no method for assessing the extent of risk under the U.S. EPA noncancer risk assessment framework.


OBJECTIVE
We estimated excess risks from ambient concentrations of acrolein based on dose-response modeling of a study in rats with a relationship between acrolein and residual volume/total lung capacity ratio (RV/TLC) and specific compliance (sC(L)), markers for altered lung function.


METHODS
Based on existing literature, we defined values above the 90th percentile for controls as "adverse." We estimated the increase over baseline response that would occur in the human population from estimated ambient concentrations of acrolein, taken from the U.S. EPA's National-Scale Air Toxics Assessment for 1999, after standard animal-to-human conversions and extrapolating to doses below the experimental data.


RESULTS
The estimated median additional number of adverse sC(L) outcomes across the United States was approximately 2.5 cases per 1,000 people. The estimated range of additional outcomes from the 5th to the 95th percentile of acrolein concentration levels across census tracts was 0.28-14 cases per 1,000. For RV/TLC, the median additional outcome was 0.002 per 1,000, and the additional outcome at the 95th percentile was 0.13 per 1,000.


CONCLUSIONS
Although there are uncertainties in estimating human risks from animal data, this analysis demonstrates a method for estimating health risks for noncancer effects and suggests that acrolein could be associated with decreased respiratory function in the United States.
Woodruff
Tracey J
TJ
Office of Policy, Economics and Innovation, U.S. Environmental Protection Agency, San Francisco, California 94118, USA. tracey.woodruff@ucsf.edu
Wells
Ellen M
EM
Holt
Elizabeth W
EW
Burgin
Deborah E
DE
Axelrad
Daniel A
DA
D000171:Acrolein / Q000633:toxicity*; D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure / Q000009:adverse effects*; D006801:Humans; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008170:Lung Compliance / Q000187:drug effects; D008954:Models, Biological; D051381:Rats; D012115:Residual Volume / Q000187:drug effects; D018570:Risk Assessment; D014481:United States
D000393:Air Pollutants; D000171:Acrolein