Intake Assessment.
Here is the generic formula for calculating intake of a chemical. It looks a little intimidating, but it's simpler than it looks:
The units of Intake are milligrams per kilogram per day, usually the kg and day are written together or with a space, that's not a minus sign between them, it just looks like one.)
C = Concentration of chemical (let's call it chemical Z) in medium (i.e., mg of Z / L of water, or mg of Z / kg of beans)
CR = Contact rate with medium, or the amount of medium contacted per period of time (i.e., L of water drank / day, or kg of beans eaten / day.)
EF = Exposure frequency, or how often the medium is contacted (days of contact / calendar year)
ED = Exposure duration, or how long the exposure (contact with the contaminant) occurs ( years until receptor moves away, or years until contaminant disappears)
BW = Body weight of receptor (kg, default to 70 kg for adults)
AT = Averaging time (days) This is one of two numbers, depending upon if we are considering carcinogenic or non-carcinogenic effects of chemical Z. In module 6B I will try to explain the rationale for this, but for carcinogens, the AT is 365 days / year times 70 years. For non-carcinogens the AT is (usually) the period of time over which the the exposure occurred. Don't get hung up here. Or, do module 6B first.
Let's look at an example. NEXT