indir.exposure: indir.exposure

In HumanExposure/SHEDSDevel: The SHEDS-HT model for estimating human exposure to chemicals.

Description

Models the indirect exposure to chemicals in the home for each theoretical person.

Usage

indir.exposure(sd, cb, concs, chem.data)

Arguments

sd	The chemical-scenario data specific to relevant combinations of chemical and scenario. Generated internally.
cb	A copy of the base data set output from the make.cbase function, with columns added for exposure variables.
concs	The concentration of the chemical (in air and/or on surfaces) being released into the environment. Outpu of the get.fug.concs function.
chem.data	The list of scenario-specific information for the chemicals being evaluated. Generated internally.

Details

Indirect exposure happens after a product is no longer being used or applied, due to chemical lingering on various surfaces or in the air. People who come along later may receive dermal or inhalation exposure from residual chemical in the environment. SHEDS.HT currently has two indirect exposure scenarios. One which applies to a one-time chemical treatment applied to a house, and another which applies to continual releases from articles. Both scenarios consist of two parts: the first determines the appropriate air and surface concentrations. That code is in the Fugacity module. The second part is the exposure calculation by the current function. Both types of indirect exposure scenarios call this function. The surface and air concentrations from the Fugacity module are premised on the product use actually occurring. Hence, indir.exposure starts by multiplying those concentrations by the prevalence (which is either 0 or 1, evaluated separately for each person). For air, the exposure is the average daily concentration, which is the event concentration multiplied by the fraction of the day spent in that event. The inhaled dose is the product of the exposure, the basal ventilation rate, and the PAI factor (multiplier for the basal rate). A factor of 1E+06 converts the result from grams per day to micrograms per day. Dermal exposure results from skin contact with surfaces. The surface concentration (ug/cm2) is multiplied by the fraction available for transfer (avail.f, unitless), the transfer coefficient (dermal.tc, in cm2/hr), and the contact duration (hr/day). The result is the amount of chemical transferred onto the skin (ug/day).

Value

indir Indirect exposure to chemicals in the home in ug per person per day.

Author(s)

Kristin Isaacs, Graham Glen

See Also

Fugacity, get.fug.concs, make.cbase, run

HumanExposure/SHEDSDevel documentation built on Oct. 30, 2019, 6:49 p.m.