Notice of Adoption of Inhalation Cancer Unit Risk Factor for Perchloroethylene

The Office of Environmental Health Hazard Assessment (OEHHA) is adopting an updated inhalation cancer unit risk factor (URF) for perchloroethylene (PCE or tetrachloroethylene).  URFs are used to estimate lifetime cancer risks associated with inhalation exposure to a carcinogen. 

OEHHA is required to develop guidelines for conducting health risk assessments under the Air Toxics Hot Spots Program (Health and Safety Code Section 44360(b)(2)).  In implementing this requirement, OEHHA develops new URFs and revises existing URFs for many air pollutants.  The existing inhalation URF for PCE was revised using the most recent “Air Toxics Hot Spots Program Technical Support Document for Cancer Potency Factors,” finalized by OEHHA in 2009.

The values for PCE are as follows:

  • Inhalation Cancer Unit Risk (URF): 6.1 x 10-6 (µg/m3)-1
  • Inhalation Cancer Slope Factor (CSF): 2.1 x 10-2 (mg/kg-day)-1

Please direct any inquiries concerning technical matters or availability of the document to:

Dr. Ken Kloc
Air Toxicology and Risk Assessment Section
Air, Community, and Environmental Research Branch
Office of Environmental Health Hazard Assessment
1515 Clay Street, 16th Floor
Oakland, CA, 94612

Telephone: (510) 622-3163