Public Comment Period and Workshops on the Draft Hot Spots Cancer Inhalation Unit Risk Factors for Cobalt and Cobalt Compounds

The Office of Environmental Health Hazard Assessment (OEHHA) is releasing a document for public review that summarizes the carcinogenicity and derivation of cancer inhalation unit risk factors (IURs) for cobalt and cobalt compounds.  Cancer inhalation unit risk factors 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 IURs for many air pollutants.  The draft cobalt and cobalt compounds inhalation cancer unit risk factors were developed using the most recent “Air Toxics Hot Spots Program Technical Support Document for Cancer Potency Factors,” finalized by OEHHA in 2009.

The draft cobalt and cobalt compounds inhalation cancer unit risk factor document is being made available today on the OEHHA website.  The posting of the document will commence a 45-day public review period that will end on April 22, 2019.  Public workshops will be held in Northern and Southern California at the following locations and times:

Southern California                                               Northern California
March 26, 2019                                                        March 28, 2019
10:00 AM - 12:00 PM                                              10:00 AM – 12:00 PM        
Room CC-2                                                              George Alexeeff Environmental Health Library
​South Coast Air Quality Management District
21865 E. Copley Drive                                            1515 Clay St., 16th Floor
Diamond Bar, CA 91765                                         Oakland, CA 94612

After the close of the public comment period, the document will be revised as appropriate by OEHHA, and peer reviewed by the state’s Scientific Review Panel on Toxic Air Contaminants. 

The public is encouraged to submit written information via OEHHA’s website, rather than in paper form.  Comments may be submitted electronically through the following link:

Hard-copy comments may be mailed, faxed, or hand-delivered to the address below:

Dr. John Budroe
Chief, Air Toxicology and Risk Assessment Section
Air and Site Assessment and Climate Indicators Branch
Office of Environmental Health Hazard Assessment
1515 Clay Street, 16th Floor
Oakland, CA, 94612
Telephone: (510) 622-3145

Information about dates and agenda for meetings of the Scientific Review Panel can be obtained from the California Air Resources Board website at