An internal investigation has found that the Environmental Protection Agency failed to disclose long-term cancer risks and a small chance of death to 81 human test subjects who consented to breathe in diesel exhaust and other pollutants during experiments.
The inspector general's report released Wednesday said that at least some people participating in studies in 2010 and 2011 would like to have known whether a study involves a chance of death, no matter how small.
While diesel fumes include 19 potentially cancer-causing substances, an EPA manager said cancer risk was irrelevant because subjects were exposed for two-hour periods. Cancer typically develops over years of exposure.
The EPA agreed to disclose all risks on future consent forms.
The agency has conducted air pollutant studies on humans for 40 years.