Table 20.

Incidence of tumours in mice administered short‐chain chlorinated paraffin (C₁₂, 60% chlorination) (NTP, 1986a)

	Males			Females
Dose (mg/kg bw per day)	Control	125	250	Control	125	250
Hepatocellular adenomas	11/50 (22%)	20/50 (40%)a , b	29/50 (58%)a , b	0/50 (0%)	18/50 (36%)a , b	22/50 (44%)a , b
Hepatocellular carcinomas	11/50 (22%)	15/50 (30%)	17/50 (34%)	3/50 (6%)	4/50 (8%)	9/50 (18%)a
Hepatocellular adenomas or carcinomas	20/50 (40%)c	34/50 (68%)a , b	38/50 (76%)a , b	3/50 (6%)d	22/50 (44%)a , b	28/50 (56%)a , b
Thyroid follicular cell adenomas or carcinomas	3/49 (6%)	4/50 (8%)	3/49 (6%)	8/50 (16%)e	12/49 (24%)	15/49 (31%)a , b
Harderian gland adenomas	–	–	–	1/50 (2%)f	6/50 (12%)a , b	2/50 (4%)
Alveolar/bronchiolar carcinomas	0/50 (0%)g	3/50 (6%)	6/50 (12%)a , b	–	–	–

bw: body weight.

^aLife table analysis, p < 0.05, increase relative to control.

^bIncidental tumour test for trend, p < 0.05, increase relative to control.

^cHistorical incidence at the study laboratory (mean ± SD): 109/298 (37% ± 12%); historical incidence in NTP studies: 357/1,091 (33% ± 10%).

^dHistorical incidence at the study laboratory (mean ± SD): 18/300 (6% ± 3%); historical incidence in NTP studies: 74/1,092 (7% ± 4%).

^eHistorical incidence at the study laboratory (mean ± SD): 19/291 (7% ± 3%); historical incidence in NTP studies: 40/1,009 (4% ± 3%).

^fHistorical incidence at the study laboratory (mean ± SD): 5/300 (2% ± 2%); historical incidence in NTP studies: 21/1,096 (2% ± 3%).

^gNo specific historical incidence data reported for alveolar/bronchiolar carcinomas. Historical incidence of the alveolar/bronchiolar tumours (adenomas and carcinomas) at the study laboratory (mean ± SD): 54/298 (18% ± 7%); historical incidence of the alveolar/bronchiolar tumours in NTP studies: 169/1,093 (15% ± 6%).