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How It Works
This calculator covers five standard environmental risk-assessment equations used in toxicology and public health: probability of adverse effects, carcinogenic risk, non-carcinogenic hazard index, standard mortality ratio, and administered dose. Select the equation type, choose what to solve for, and enter your values.
Example Problem
In a population of 100,000 people, 15 develop an adverse health effect. What is the probability?
- P = X / N = 15 / 100,000 = 0.00015 (1.5 × 10−4)
The EPA generally considers lifetime cancer risks above 1 × 10−4 to warrant action.
Frequently Asked Questions
What is a carcinogenic slope factor?
The slope factor (SF) converts chronic daily intake into an estimated probability of developing cancer over a lifetime. It is expressed in units of (mg/kg/day)−1 and is specific to each chemical.
What does a hazard index greater than 1 mean?
A hazard index above 1.0 indicates the exposure exceeds the reference dose and may pose a non-carcinogenic health risk. Values below 1.0 are generally considered safe for chronic exposure.
What is the standard mortality ratio?
The SMR compares the mortality rate in an exposed group to that in an unexposed group. An SMR of 2.0 means the exposed population has twice the death rate, suggesting a strong association with the exposure.
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References: Vesilind, Peirce & Weiner. 1994. Environmental Engineering. 3rd ed. LaGrega, Buckingham & Evan. 1994. Hazardous Waste Management. McGraw Hill.