The mice were exposed to maximum tolerated doses of formaldehyde (15ppm), more than 100 times the occupational exposure limit, and did not develop nasal tumors or demonstrate any increased prevalence of leukemia or any other type of cancer. 

These findings add to a growing body of evidence that formaldehyde inhalation does not cause leukemia, as supported by a recently published, peer-reviewed article in the well-known journal Regulatory, Toxicology and Pharmacology.