Lifetime Average Daily Dose

Integrate nonoverlapping exposure calendar segments into lifetime-average daily dose, with nonexposed days contributing zero; lifetime and exposures are caller scenarios.

Description

Average ordered, nonoverlapping daily-dose segments over an explicit lifetime in days.

Lifetime-average daily dose spreads cumulative exposure across a specified lifetime, including periods without exposure. It is an averaging convention used in some chronic cancer-risk assessments and differs from the dose received on an exposure day.^[1]

This tool receives a calendar of constant daily-dose segments. Starts and durations use days; dailyDosesMgPerKg represents mg/kg/day despite its abbreviated field name. Segment contributions and lifetimeAverageDailyDose also use mg/kg/day. Unlisted calendar gaps contribute zero dose.

When to use Lifetime Average Daily Dose

Use it to document intermittent or changing exposure as a nonoverlapping calendar before a compatible lifetime-based comparison.

How to use Lifetime Average Daily Dose and understand its results

Enter aligned, nonempty exposureStartDays, exposureDurationsDays, and dailyDosesMgPerKg arrays in calendar order.
Use nonnegative starts and daily doses, positive durations, and positive lifetimeDays. Every segment must end within the lifetime without overlapping the previous segment.
Run the tool and inspect segmentLifetimeContributions and lifetimeAverageDailyDose. Preserve the chosen lifetime and daily-dose basis with the result.

contribution_i = daily dose_i × duration_i / lifetime days; LADD = Σ contribution_i

Start days validate placement but do not change a segment’s weight. The implementation does not sort, merge, or apply extra exposure-frequency factors.

json

{
  "input": {
    "exposureStartDays": [
      0,
      100
    ],
    "exposureDurationsDays": [
      10,
      20
    ],
    "dailyDosesMgPerKg": [
      1,
      2
    ],
    "lifetimeDays": 1000
  },
  "output": {
    "segmentLifetimeContributions": [
      0.01,
      0.04
    ],
    "lifetimeAverageDailyDose": 0.05
  }
}

Adjacent segments and a final segment ending exactly at lifetimeDays are accepted. Fractional days are allowed. Out-of-order or overlapping segments, zero durations, and segments extending past the lifetime are rejected; zero daily doses are accepted.

Limitations and assumptions

There is no built-in lifetime, age weighting, changing body mass, or within-segment variation. Daily doses must already reflect the intended exposure frequency and absorption basis.

This average does not retain peak-dose information or model biological recovery. Concurrent sources must be combined appropriately before entering a calendar that prohibits overlapping segments.

Alternative or Complementary methods

An ingestion-dose tool can prepare compatible exposure estimates. An aggregate cancer-risk calculation can multiply appropriately defined lifetime doses by justified route-specific factors.

References

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

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