You are evaluating exposure to TCE (trichlorethylene) to an adult via drinking water. The adult's water has 12 mg / L of TCE. You are interested here in the non-carcinogenic effects of TCE.
First evaluate the parameters for the formula:
C = is given, 12 mg / L
CR = is the contact rate, in this case we call it the Ingestion Rate. We will use 2 L / day
EF = is the exposure frequency, say 365 days / year.
ED = is the exposure duration. 70 years is the assumed lifetime.
BW = is the body weight use 70 kg
AT = Averaging time. This would be 365 days /year x 70 years = (365*70 days)
Here's the generic intake formula on top and the same formula with the values of the parameters both numbers and units plugged in: