Cancer Slope Factor Risk

Evaluate a supplied oral cancer slope factor over compatible lifetime-average doses; linear extrapolations above one are preserved and flagged, not treated as probabilities.

Description

Apply a supplied oral cancer slope factor to compatible lifetime-average doses, preserving out-of-range estimates.

A cancer slope factor expresses a modeled low-dose cancer-risk increment per unit of exposure. In a linear oral assessment, multiplying a compatible lifetime-average daily dose by that factor gives a screening estimate of excess lifetime risk. The exposure basis and potency model must be justified separately.^[1]

This tool evaluates one supplied oral slope factor across a dose list. If doses use mg/kg/day, the factor must use reciprocal mg/kg/day units so the product is dimensionless. It does not turn a short-term dose into a lifetime average.

Linear extrapolation can produce a value above one. The calculator preserves that number and returns a numeric flag rather than clipping it to a probability. Such a result falls outside a probability interpretation and does not mean a person can have more than 100% risk.

When to use Cancer Slope Factor Risk

Use it to reproduce a documented low-dose linear oral risk screen or compare a set of compatible lifetime-average exposure scenarios.

How to use Cancer Slope Factor Risk and interpret its calculation

Enter a nonempty lifetimeAverageDoses list with nonnegative values on the required lifetime and dose basis.
Enter a positive oralSlopeFactor in reciprocal compatible dose units and run the calculation.
Read linearRiskEstimates and outsideProbabilityRangeFlags together in input order. A flag of one means the numerical estimate exceeds one and should not be used as a probability.

linear estimate_i = lifetime-average dose_i × oral slope factor; flag_i = 1 if estimate_i > 1, otherwise 0

Outputs are not rounded or capped. A value exactly one has flag zero.

The implementation multiplies each supplied dose by the same factor and checks the upper probability boundary. It performs no exposure averaging, slope-factor lookup, or nonlinear adjustment.

json

{
  "input": {
    "lifetimeAverageDoses": [
      0.001,
      0.002
    ],
    "oralSlopeFactor": 0.5
  },
  "output": {
    "linearRiskEstimates": [
      0.0005,
      0.001
    ],
    "outsideProbabilityRangeFlags": [
      0,
      0
    ]
  }
}

Zero dose gives estimate zero and flag zero. Exactly one remains one with flag zero. A zero slope factor is rejected even though a zero arithmetic product could be defined.

Limitations and assumptions

The factor must apply to the chemical, route, population, and assessment approach. Matching numerical units does not validate its applicability or justify extrapolation across the full dose range.

No background cancer risk, age-specific adjustment, competing risk, confidence interval, or clinical prognosis is calculated. Above-one estimates are model extrapolations rather than valid probabilities.

Alternative or Complementary methods

Construct a lifetime-average dose from a documented exposure history before applying a lifetime factor. To aggregate compatible chemical and route contributions, use a separate linear risk sum and inspect its upper-range flag too.

References

EPA's Approach for Assessing the Risks Associated with Chronic Exposure to Carcinogens — U.S. Environmental Protection Agency

Similar or alternative tools

Lifetime Average Daily Dose
Average ordered exposure segments over a supplied lifetime duration.
Aggregate Cancer Risk
Sum compatible linear dose-times-factor contributions by chemical and route.