For the 1999 national-scale assessment, EPA is estimating risks from formaldehyde using a cancer unit risk (potency) estimate developed by the CIIT Centers for Health Research (formerly the Chemical Industry Institute of Technology), published in 1999. EPA has also used the CIIT cancer potency estimate for certain air toxics rules, such as the technology-based standard for the plywood industry.
EPA has a cancer potency estimate for formaldehyde in the Integrated Risk Information System (IRIS), which was last updated in 1991 and is several orders of magnitude higher than the CIIT value. EPA is in the process of completing its IRIS assessment for formaldehyde, including an evaluation of the CIIT modeling used to estimate the cancer potency and additional studies being done by the National Cancer Institute. The results of the IRIS review are not available for the current national-scale assessment, but we expect it will be for the next assessment which will be based on 2002 emissions data.
For the current national-scale assessment, EPA has decided to present the results using only the CIIT cancer potency estimate. With the CIIT cancer potency estimate, formaldehyde is not estimated to be a national or regional risk driver for cancer, but is noted as a regional risk driver for noncancer (at least 10,000 people exposed to a hazard quotient greater than 1.0). However, with the existing IRIS cancer potency estimate, formaldehyde would be considered a national risk driver for cancer (upper bound lifetime cancer risk exceeding 10 in a million to more than 25 million people), as it was in the 1996 national-scale assessment.