exposure assessment by multi-media modelling
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Exposure Assessment by
Multi-media modelling
Cause-effect chain for ecosystem and human health as basis for exposure assessment by multi-media modelling (Fairman et al., 1998)
CalTOXCalTOX is a multimedia, multiple pathway exposure, transport and transformation model.
Applications Limitations•Site-specific: local•Time scale : from one year to decades.•Substances assessable : non-ionic organic chemicals, radionuclides, fully dissociating in-/organic chemicals, solid-phase metal species, partially dissociated in-/organic species,
Available together with information and documentation via the Internet through page:
(http://www.eetd.lbl.gov/ied/era ( version4.0):
The eight compartment model of CalTOX
Compartments considered in the model:
air plants ground-surface soil root-zone soil vadose-zone soil ground water surface water sediment
The structure of the CalTOX model with the multimedia transport, the intermedia transfer and its exposure pathways
23 pathway human exposure scenario:
All inhalation exposures indoors activeAll inhalation exposures indoors restingInhalation exposure in shower/bathInhalation exposures outdoors activeInhalation of air particles indoorsTransfer of soil dust to indoor airTransfer of soil vapors to indoor airOn-site inhalation by animals
Water
Use of ground water as tap waterUse of surface water as tap waterIngestion of tap waterUse of ground water for irrigationUse of surface water for irrigationUse of ground water for feeding animalsUse of surface water for feeding animals
PlantsContaminant transfer, air to plants surfacesContaminant transfer, ground soil to plant surfacesContaminant transfer, root soil to plant tissuesOn-site grazing of animals
Human IngestionIngestion of home-grown exposed produceIngestion of home-grown unexposed produceIngestion of home-grown meatIngestion of home-grown milkIngestion of home-grown eggsIngestion of locally caught fishDirect soil ingestion
DermalSoil contact exposure at home or at workDermal exposure during shower/bathDermal & ingestion exposures while swimming
InfantsBreast-milk ingestion by infants.
Input data of CalTOX
Data describing the substance
Physico-chemical properties
Measured emissions into the compartments
Background concentrations of the contaminant
Toxicological properties, consisting of a cancer and a non-cancer potency for human beings, since only human risk is considered in CalTOX.
Data characterising the area:
Geographical data like the contaminated area size
Meteorological and hydrological data, e.g. the average depth of surface water, the annual average precipitation, wind speed or environmental temperature
Soil properties, like the organic carbon fractions
Data about the human population, e.g. the average body weight or daily intake rates for different kinds of food.
Output data of CalTOX
Predicted concentrations in:breast milkfishmilkmeateggstap waterswimming water
Estimated exposure media concentrationsindoor airoutdoor airbathroom airtap waterswimming waterun-/exposed producemeatmilkeggsfish and seafoodhousehold soil
Some properties like fugacity capacities or boundary layer thickness in different media are also calculated.
Daily human doses by:
inhalation,ingestion (breast milk, water, milk, meat, fish, soil)dermal uptake
Final results:
Individual human lifetime Risk for developing cancer
Risk = chronic daily intake * slope factor
Hazard ratio for non-carcinogenic effects attributable to exposure over a certain period which can be defined by the user.
Hazard ratio = intake/reference dose
Inputs used in CalTOXPhysico-chemical properties
Molecular weightMelting pointVapour pressureWater solubilityHenry's law constantOctanol-water partition coefficient (KOW)Organic carbon-water partition coefficient
(KOC)
Degradation ratesHalf-life time in airHalf-life time in waterHalf-life time in sedimentHalf-life time in soilEmission to regional airEmission to regional surface waterRegional emissions to soil
Time- Averaging time- Exposure duration
Area description- Area- Average wind speed- Average annual precipitation- Average environmental temperature
Humans description- Egg intake- Grain intake- Fruit and vegetable intake- Milk intake- Fish intake- Meat intake- Body weight
Accumulation behaviour- Bioconcentration factor for fish- Cancer potency factor- Non-cancer ADI
Predicted concentrations in environmental media:
air air (gases)air (particles)(annual) average in air (total)
soil ground soilroot zone soilvadose zone soiloff-site surface soilground water surface water
annual average in surface water
sediment sedimentaquifer
Predicted concentrations in exposure mediaCalTOX• plants/grass• fish/seafood• meat• milk• drinking water• eggs• breast milk• swimming water• indoor air• bathroom air• outdoor air• household soil
Doses CalTOXDaily human doses through intake of
• drinking water• air• fish• meat• milk• total• eggs• soil• breast milk (infants)
daily inhalation by humans of• surface soil• root-zone soil• ground water• surface water• total
Daily dermal uptake by humans from
• surface soil• root-zone soil• ground water• surface water• total
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