PEC-PNEC Ratio Calculator
Independently matched PEC/PNEC risk-screen ratio, not probability, safe concentration or an authoritative PNEC derivation. Actual independently matched quantities/units required; not infer causal effect, clinical guidance or safe design.
Description
A PEC/PNEC ratio compares a predicted environmental concentration with an applicable predicted no-effect concentration.
A PEC/PNEC ratio compares a predicted environmental concentration with an applicable predicted no-effect concentration.1
It does not derive either input or express a probability of ecological harm.
When to use PEC-PNEC Ratio Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the chemical, exposure route, endpoint, measurement basis and independently applicable assay or assessment reference.
How to use PEC-PNEC Ratio Calculator and understand its results
- Establish the chemical, exposure route, endpoint, measurement basis and independently applicable assay or assessment reference.
- Enter callerSiteSpecificPredictedEnvironmentalConcentration, callerIndependentlyApplicablePnec, using the field meanings and rules below, then run the tool.
- Read result.observedRatio. Use the units and subtraction order below to interpret each value; retain negative differences where returned.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| callerSiteSpecificPredictedEnvironmentalConcentration | Caller site specific predicted environmental concentration | number | Required |
| callerIndependentlyApplicablePnec | Caller independently applicable pnec | number | Required |
Require a finite nonnegative numerator and strictly positive denominator. Divide the supplied measurements without converting their units or clamping the result. The implementation does not enforce numerator≤denominator, so a ratio above one can be returned. Use independently compatible definitions and units.
observedRatio=numerator/denominator Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Qualified observed calculation or explicit reference | object |
| result.observedRatio | Declared numerator divided by matched denominator on the stated compatible basis; no upper-one clamp. | number |
{
"input": {
"callerSiteSpecificPredictedEnvironmentalConcentration": 2,
"callerIndependentlyApplicablePnec": 4
},
"output": {
"result": {
"observedRatio": 0.5
}
}
}Limitations and assumptions
Chemical identity, route, assay, exposure basis and reference applicability are caller-established. The output supplies no causal conclusion, universal toxicity threshold or authoritative regulatory determination.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use Risk Characterization Ratio Calculator: A risk-characterization ratio compares an exposure estimate with an independently derived effect reference. For a complementary comparison, use PNEC Calculator: A predicted no-effect concentration is an assessment-derived environmental reference.
References
-
PEC-PNEC Ratio Calculator — tool.io
Similar or alternative tools
- Risk Characterization Ratio Calculator
A risk-characterization ratio compares an exposure estimate with an independently derived effect reference.
- PNEC Calculator
A predicted no-effect concentration is an assessment-derived environmental reference.