Enter the No Observed Adverse Effect Level (NOAEL), body weight, uncertainty factor, and conversion/modifying factor into the calculator to estimate the permissible daily exposure (PDE).
Educational estimate only; not medical, toxicology, or regulatory advice. Do not use this tool to set personal “safe exposure” limits, medication dosing, or supplement dosing. For formal PDE/risk assessments, consult qualified professionals and appropriate guidance (e.g., recognized regulatory toxicology frameworks); if you think you’ve been exposed to a harmful substance, contact a medical professional or poison control.
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Permissible Daily Exposure Formula
The following simplified formula is used here to estimate the permissible daily exposure (PDE) as a total amount per day (e.g., mg/day) from a NOAEL expressed per body weight (e.g., mg/kg/day), along with body weight and adjustment factors.
PDE_{mg/day} = \frac{NOAEL_{mg/kg/day} \times BW_{kg}}{UF \times CF}Variables:
- PDE is the permissible daily exposure (typically expressed here as mg/day or µg/day)
- NOAEL is the no observed adverse effect level (commonly expressed here as mg/kg/day or µg/kg/day)
- BW is body weight (kg)
- UF is an uncertainty factor (unitless; chosen based on scientific judgment/guidance)
- CF is a conversion/modifying factor (unitless; chosen based on context/guidance)
To calculate the PDE in mg/day, multiply NOAEL (mg/kg/day) by body weight (kg), then divide by the product of UF and CF.
What is Permissible Daily Exposure?
Permissible Daily Exposure (PDE) is a health-based guidance value commonly used in pharmaceutical quality and risk assessment to set conservative exposure limits. It is typically derived from toxicology data (such as a NOAEL) and adjusted using uncertainty and modifying factors to account for variability, data gaps, and other considerations. A PDE is an estimate with uncertainty and does not guarantee “no adverse effects” for every person or scenario.
How to Calculate Permissible Daily Exposure?
The following steps outline how to calculate the Permissible Daily Exposure (PDE).
- Determine the No Observed Adverse Effect Level (NOAEL) in appropriate units (commonly mg/kg/day).
- Determine the body weight (BW).
- Select the uncertainty factor (UF) based on the context and applicable guidance.
- Select the conversion/modifying factor (CF) based on the context and applicable guidance.
- Calculate the PDE using: PDE (mg/day) = (NOAEL (mg/kg/day) × BW (kg)) / (UF × CF).
- After inserting the values and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
No Observed Adverse Effect Level (NOAEL) = 50 mg/kg/day
Body Weight (BW) = 70 kg
Uncertainty Factor (UF) = 10
Conversion / Modifying Factor (CF) = 1
PDE = (50 mg/kg/day × 70 kg) / (10 × 1) = 350 mg/day
