Table 3.

Incidence of intestinal lesions in female rodents of NTP (2008b) bioassay^†.

mg/l SDD:	0	14	57	172	516
mg/l Cr(VI):	0	5	20	60	180
Duodenum
Histiocytic infiltration (rat)‡	0/50 (0/46)	0/50 (0/49)	4/50 (1/48)	33/50** (30/46)**	40/50** (47/50)**
Focal hyperplasia	0/50	0/50	1/50	2/50	0/50
Diffuse hyperplasia	0/50	16/50**	35/50**	31/50**	42/50**
Adenoma	0/50	0/50	2/50‖	13/50***	12/50***
Carcinoma	0/50	0/50	0/50	1/50#	6/50*
Jejunum¶
Histiocytic infiltration	0/50	0/50	0/50	2/50	8/50*
Diffuse hyperplasia	0/50	2/50	1/50	0/50	8/50**
Adenoma	0/50	1/50‖	0/50	2/50‖	5/50*
Carcinoma	1/50	0/50	2/50‖	2/50‖	1/50
Combined tumors in small intestine§	1/50	1/50	4/50‖	17/50***	22/50***

†Results for male mice are not shown (but were similar to female mice).

‡Histiocytic infiltration was the only histopathological response reported in female (shown) and male (not shown) rat duodenum.

¶No lesions were reported in the female or male rat jejunum.

§No intestinal tumors were observed in female or male rats.

‖Exceeded historical control ranges for all routes of exposure.

#Exceeded historical control range for drinking water studies.

*p ≤ 0.05,

**p ≤ 0.01 or

***p ≤ 0.001 compared to concurrent control by poly-3 test; tumors and hyperplasia in mice were significant for trend.

Source: Detailed results and statistical analyses can be found in NTP (2008b) and Stout et al. (2009a).