Chronic Daily Intake

\[CDI=\frac{C\times IR\times EF\times ED}{BW\times AT}\]

Variables

CDIchronic daily intake (mg/kg/day)

Ccontaminant concentration (mg/L)

IRintake rate (L/day)

EFexposure frequency (days/year)

EDexposure duration (years)

BWbody weight (kg)

ATaveraging time (days)

Description

What is this formula?

The Chronic Daily Intake (CDI) estimates the average amount of a contaminant absorbed per kilogram of body weight each day over a long-term exposure period.

When to use it

Use this formula in environmental and human health risk assessments to estimate long-term exposure to contaminants present in water, food, air, soil, or workplace environments.

Example

A person consumes water containing a contaminant concentration of 0.02 mg/L.

Data:

C = 0.02 mg/L

IR = 2 L/day

EF = 350 days/year

ED = 30 years

BW = 70 kg

AT = 30 × 365 = 10950 days

Formula:

CDI = (C × IR × EF × ED) / (BW × AT)

Substitution:

CDI = (0.02 × 2 × 350 × 30) / (70 × 10950)

Result:

CDI = 0.000548 mg/kg/day

Applications

- Human health risk assessment

- Environmental toxicology

- Drinking water studies

- Soil contamination investigations

- Regulatory exposure analysis

Note

This formula is an exposure assessment model used extensively by environmental and regulatory agencies. Variations exist depending on the exposure pathway, regulatory framework, and assumptions regarding averaging time and exposure frequency.