Authors: Daniel L. Morgan, Darlene Dixon, Debra H. King, Greg S. Travlos, Ronald A. Herbert, John E. French, Erik J. Tokar, Michael P. Waalkes, Michael P. Jokinen.
The objective of the NTP study was to evaluate the potential role of the Trp53 gene in nasal carcinogenicity, leukemia or lymphohematopoietic cancer, and potentially other neoplasms in genetically susceptible mice. Male Trp53 haploinsufficient (Trp53+) mouse strains (B6.129-Trp53tm1Brd and C3B6.129F1-Trp53tm1Brd) were exposed via inhalation to 0 ppm, 7.5 ppm or 15 ppm formaldehyde for 8 weeks. Because evidence suggests a possible role of the Trp53 gene in formaldehyde-induced nasal squamous cell carcinomas, the authors hypothesized that formaldehyde-induced loss of Trp53 would result in an increase in susceptibility to formaldehyde-induced nasal squamous cell carcinoma, and possibly leukemia and other neoplasms. However, the study found that inhalation of a maximum tolerated dose of formaldehyde did not cause nasal tumors, an increased prevalence of leukemia or lymphohematopoietic cancer, or any other type of cancer in Trp53+ mice. The results from this study increase the weight of evidence that formaldehyde exposure is not causally associated with leukemia.