Table 1.
Equations used to calculate the animal dose, human dose, human exposure factor (EF), human cancer slope factors (CSFh), human cancer risks and intakes for reduced risk levels
| Equation number | Equation name (units) | Equation description |
|---|---|---|
| {1} | Animal dose (mg/kg-day) | Ca × (IRa ÷ BWa) × EFa |
| {2} | Human dose (mg/kg-day) | Ch × (IR ÷ BWh) × EFh |
| {3} | Animal exposure factor | (6.2 hours ÷ 24 hours) × (5 days ÷ 7 days) |
| {4} | Human exposure factor | (8 hours ÷ 24 hours) × (5 days/week × 50 weeks/year × ED) ÷ (ED × 365 days/year) |
| {5} | CSFh (mg/kg-day)−1 | CSFa × (BWh ÷ BWa)1/4 |
| {6} | Human cancer risk | Dh × CSFh × (ED ÷ AT) |
| {7} | Intake level (IL) associated with a cancer risk of one in a million (μg/day); | ((10−6 × BWh) ÷ CSFh) × 1000 (μg/mg) |
| {8} | Workplace air concentration (mg/m3) associated with IL | (IL × 0.001 mg/μg) ÷ IRo |
Concentrations used to estimate animal doses were obtained from the NTP study (0, 3, 10, and 30 mg/m3), and the OSHA PEL and EU antimony occupational estimates were used as human concentrations. Default values were used for human and animal inhalation rates and body weights. The animal exposure factor reflects the time per day and days per week that animals were exposed in the NTP studies, and the human exposure factor reflects exposure across a typical occupational career. An exposure duration of 20 or 40 years and averaging time of 70 years were used in estimating cancer risk.
Default values: IRa=0.0345 m3/day; IRh=20 m3/day; BWa=weighted average BW of the control; BWh=70 kg; ED=20 or 40 years; AT=70 years; IRo=10 m3/day.
AT, averaging time (year); BWa, animal body weight (kg); BWh, human body weight (kg); Ca, animal concentration (mg/m3); Ch, human concentration (mg/m3); CSFa, animal cancer slope factor (mg/kg-day)−1; CSFh, human cancer slope factor (mg/kg-day)−1; Dh, human dose (mg/kg-day); ED, exposure duration (year); EFa, animal exposure factor; EFh, human exposure factor; IL, intake level associated with cancer risk of one in a million (μg/day); IRa, animal inhalation rate (m3/day); IRh, human inhalation rate (m3/day); IRo, human occupational intake rate (m3/day); OSHA, Occupational Safety and Health Administration; PEL, Permissible Exposure Limit.