What is equivalent daily human intake for an 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
This page was prepared by M. Kamrin, Michigan State University. April 1997. Extoxnet FAQs Team.