Exposure Assessment by Multi-media modelling

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