Table 19.

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

	Males			Females
Dose (mg/kg bw per day)	Control	312	625	Control	312	625
Hepatocellular neoplastic nodules	0/50 (0%)	10/50 (20%)a , b	16/48 (33%)a , b	0/50 (0%)	4/50 (8%)a	7/50 (14%)a , b
Hepatocellular carcinomas	0/50 (0%)	3/50 (6%)a , b	2/48 (4%)	0/50 (0%)	1/50 (2%)	1/50 (2%)
Hepatocellular neoplastic nodules or carcinomas	0/50 (0%)c	13/50 (26%)a , b	16/48 (33%)a , b	0/50 (0%)d	5/50 (10%)a	7/50 (14%)a , b
Renal tubular‐cell adenomas or adenocarcinomas	0/50 (0%)e	9/50 (18%)a , b	3/49 (6%)	0/50 (0%)	0/50 (0%)	0/50 (0%)
Mononuclear cell leukaemia	7/50 (14%)f	12/50 (24%)a	14/50 (28%)a	11/50 (22%)g	22/50 (44%)a	16/50 (32%)
Thyroid follicular cell adenomas or carcinomas	3/50 (6%)	3/50 (6%)	3/50 (6%)	0/50 (0%)h	6/50 (12%)a , b	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): 8/299 (3% ± 3%); historical incidence in NTP studies: 43/1,098 (4% ± 4%).

^dHistorical incidence at the study laboratory (mean ± SD): 2/300 (0.7% ± 1%); historical incidence in NTP studies: 21/1,098 (2% ± 3%).

^eHistorical incidence at the study laboratory (mean): 1/300 (0.3%); historical incidence in NTP studies: 5/1,098 (0.5%).

^fHistorical incidence at the study laboratory (mean ± SD): 19/300 (6% ± 6%); historical incidence in NTP studies: 152/1,100 (14% ± 8%).

^gHistorical incidence at the study laboratory (mean ± SD): 36/300 (12% ± 6%); historical incidence in NTP studies: 196/1,100 (18% ± 9%).

^hHistorical incidence at the study laboratory (mean ± SD): 3/297 (1% ± 1%); historical incidence in NTP studies: 15/1,076 (1% ± 2%).