Additional information about study design, protocols, and test article preparation and validation is available in

NTP (2008) Specifications for the conduct of studies to evaluate the toxic and carcinogenic potential of chemical, biological and physical agents in laboratory animals for the National Toxicology Program (NTP)

https://hero.epa.gov/hero/index.cfm/reference/details/reference_id/4135252

F344 Rat (10/sex/group)

Water: 0, 62.5, 125, 250, 500, 1,000 ppm sodium dichromate dihydrate;

21.81, 43.62, 87.24, 174.48, 348.97 ppm Cr(VI)

equivalent to 0, 1.7, 3.5, 5.9, 11.2, 20.9 mg Cr VI/kg-d (M/F)

"Exposure concentrations of 62.5, 125, 250, 500, and 1,000 mg/L resulted in average daily doses of approximately 5, 9, 17, 32, and 60 mg/kg body weight to males and 5, 10, 18, 33, and 61 mg/kg to females." (in units of sodium dichromate dihydrate)

While synthesis text cites equivalent doses in males/females for simplicity, the following values (more accurate) are used for dose-response:

Female F344 rats:1.74, 3.49, 6.28, 11.5, 21.3 mg/kg-d Cr(VI)

Male F344 rats: 1.74, 3.14, 5.93, 11.2, 20.9 mg/kg-d Cr(VI)

B6C3F1 Mouse (10/sex/group)

Water: 0, 62.5, 125, 250, 500, 1,000 ppm sodium dichromate dihydrate;

21.81, 43.62, 87.24, 174.48, 348.97 ppm Cr(VI)

equivalent to 0, 3.1, 5.3, 9.1, 15.7, 27.9 mg Cr VI/kg-d (M/F)

B6C3F1, BALB/c, am3-C57BL/6 Mouse, Male (5–10/group)

Strain Comparison Study

Water: 0, 62.5, 125, 250 ppm sodium dichromate dihydrate;

21.81, 43.62, 87.24 ppm Cr(VI)

equivalent to

0, 2.8, 5.2, 8.7 mg Cr VI/kg d

7 d/wk, 3 mo

Male am3-C57BL/6 mice