Table 2.

Nasal epithelial squamous cell carcinomas (SCC) in combined groups of male and female rats from four long-term inhalation studies^a with formaldehyde (FA) exposures

FA (ppm)	Rats with SCC/group size (% with SCC)
0	0/453 (0)
0.3	0/32 (0)
0.7	0/90 (0)
2	0/364 (0) (apparent NOAEC)
6	3/325 (0.9) (apparent LOAEC)
10	20/90 (22)
14	103/232 (44)
15	120/278 (43)

^aKerns et al. (1983), Sellakumar et al. (1985), Monticello et al. (1996) and Kamata et al. (1997). For review of details, see Nielsen and Wolkoff (2010) and Nielsen et al. (2013)