Exposure Dose

Aggregate changing concentration/intake/absorption scenarios over explicit segment durations; absorbed doses are not interchangeable with administered-dose reference values.

Description

Calculate absorbed ingestion doses for exposure segments and their duration-weighted average.

An ingestion-dose estimate connects an environmental concentration with the amount consumed and body mass. An absorption fraction further distinguishes material taken in from material assumed to be absorbed. Exposure averages depend on the time period represented by the inputs.^[1]

This tool treats each segment as having constant concentration, daily intake, and absorption fraction. It calculates absorbed dose in mg/kg/day for every segment and weights those doses by segment duration in days. Body mass is held constant across segments.

The resulting average covers only the total duration you supplied. It is not automatically a lifetime-average dose. Include zero-exposure periods as explicit positive-duration segments if they belong in the intended averaging period.

When to use Exposure Dose

Use it to summarize a segmented ingestion history or compare changing concentration, intake, or absorption while retaining one body-mass assumption.

How to use Exposure Dose and interpret its calculation

Enter aligned, nonempty concentrationsMgPerLiter, dailyIntakeLiters, segmentDurationsDays, and absorptionFractions lists.
Use nonnegative concentrations and intake, positive durations, fractions between 0 and 1, and a positive bodyMassKg. Represent the intake as a daily amount appropriate to each segment.
Run the calculation and read both segmentAbsorbedDosesMgPerKgDay and timeWeightedDoseMgPerKgDay. Confirm the averaging period and dose basis before comparing a benchmark.

D_i = C_i × I_i × f_i / body mass; average D = Σ(D_i × duration_i) / Σ duration_i

Concentration is mg/L, daily intake is L/day, duration is days, and f is the absorbed fraction.

The implementation first calculates each segment dose, then forms the duration-weighted mean. It has no separate exposure-frequency input; any intermittency must be reflected consistently in the daily intake or segmentation.

json

{
  "input": {
    "concentrationsMgPerLiter": [
      1,
      2
    ],
    "dailyIntakeLiters": [
      2,
      1
    ],
    "segmentDurationsDays": [
      10,
      20
    ],
    "absorptionFractions": [
      0.5,
      1
    ],
    "bodyMassKg": 50
  },
  "output": {
    "segmentAbsorbedDosesMgPerKgDay": [
      0.02,
      0.04
    ],
    "timeWeightedDoseMgPerKgDay": 0.03333333333333333
  }
}

Zero concentration, intake, or absorption makes that segment dose zero while its duration still contributes to the averaging denominator. A zero-duration segment is rejected. Multiplying every duration by the same positive factor preserves the weighted mean.

Limitations and assumptions

It does not model changing body mass, pharmacokinetics, concentration trends within segments, chemical transformations, or variation across people. The supplied constant values define each segment.

An absorbed dose is not directly interchangeable with an administered-dose reference value. This calculation does not choose reference doses, establish a lifetime averaging period, or estimate probability of harm.

Alternative or Complementary methods

For several routes, reconcile dose units and time intervals before aggregating absorbed amounts. A hazard quotient requires an exposure estimate and reference dose on a compatible route, duration, and administered or absorbed basis.

References

Risk Assessment Guidance for Superfund, Volume I, Part A — U.S. Environmental Protection Agency

Similar or alternative tools

Aggregate Exposure
Apply route-specific absorption fractions to supplied administered dose amounts.
Hazard Quotient
Compare a compatible daily exposure dose with a separately supplied reference dose.