Consumer products exposure models
Models for exposure to consumer products (including pesticides, personal care products, cleaning products, etc.) must usually account for multiple exposure pathways. Dermal contact and ingestion - particularly non-dietary ingestion - are important routes of exposure. Inhalation may also be considered. These models may vary greatly in their approach to modeling exposure or intake/dose.
Scope
Models of exposure to consumer products are needed to provide estimates of potential risks arising from contact with, and use of, everyday household articles and materials.
The main limitations are:
- Ingestion and dermal contact rates are very heterogeneous within and across populations - quantification of this information is time- and resource-intensive, so data are not widely available. Rates in children and workers tend to be better studied than in other populations.
- Transfer coefficients and absorption rates are not well quantified for many substances. QSAR has been used in some cases, but the relationships have not been established as robust yet.
Method description
- Source emissions
- Time-activity patterns for the population of interest (e.g. children, elderly, adults, etc.)
- Contact times and behaviour
- Intake rates
- Transfer coefficients
- Physiological parameters (if dose is of interest)
- Absorbed dose
- Intake
- Exposure concentration
Consumer product models may calculate exposure or intake. Intake is most likely if the exposure routes are ingestion or dermal uptake.
Exposure = Σ(concentration (= dilution x temporal decay x removal x medium transfer) x contact time/rate)
or
Intake = Σ(concentration (= dilution x temporal decay x removal x medium transfer) x intake rate)
Models account for exposure or intake during specific use scenarios, and may treat multiple pathway exposure either in sum or separately. Default source values and parameters are possible in some models if the user does not have further information.
Consumer products exposure models can be deterministic or stochastic in approach.
Generally, several scenarios may be investigated by a model. These scenarios involve different applications of a product. The product distribution in the environment and contact media is modelled or derived from measured concentrations and subsequent contact frequency and duration data are used to calculate exposure. Inhalation applications may or may not include inhalation rates, while intake is calculated for ingestion and dermal exposure. Some models may also include dosimetry calculations.
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