Calculating MCL

What is equivalent daily human intake for the average human? Intake = RfD × body weight = 1 × 70 = 70 mg/day (Assume RfD = 1 mg/kg/day) What concentration in drinking water would provide this intake? Water concentration = intake/water consumption = 70mg/day divided by 2 liter/day = 35 mg/liter But water consumption is assumed to be only 20% of total consumption, MCL = 35 mg/liter × 0.2 = 7 mg/liter If chemical is Class C carcinogen, divide by ten, so in this case: MCL = 7/10 = 0.7 mg/liter If chemical is Class A or B carcinogen, then: MCL = Practical Quantitation Limit