Page 190 - Materials Chemistry, Second Edition

L1644_C04.fm Page 162 Tuesday, October 21, 2003 3:13 PM

where Vc: PCDD/F concentrations in vegetables (ng/kg), VIR: vegetables in-
gestion rate (mg vegetables/day), AFIV: fraction absorption ingestion of
vegetables (unitless), and IA: fraction vegetables from the area (unitless).
3. Inhalation of resuspended particles of soil (Inhp). Contaminants that
deposit to the ground become aggregated with soil particles. Natural and
mechanical disturbances, e.g., wind, construction and demolition of build-
ings, can lead to a resuspension of particles from soil into the atmosphere.
Along with this resuspended dust, the adhering pollutants reach the atmo-
sphere and are subsequently inhaled by people who live or work in the
region. Inhalation exposure from emissions was calculated by assuming
that individuals were exposed to contaminated air and that indoor air
exposure was equal to outdoor exposure (Nessel et al., 1991) (Table 4.5):

Inhp = Sc·RES·Vr·RET·Pa·AFIn
where Sc: PCDD/F concentrations in soil (ng/kg), RES: fraction of resus-
3
pended particles from soil (unitless), Vr: ventilation rate (m /day),
RET: fraction retained in lungs (unitless), Pa: particle concentration
3
(µg/m ), and AFIn: fraction absorption inhalation (unitless).
4. Air inhalation (Inh; Table 4.5). The inhaled quantity of an airborne
pollutant depends mainly on the atmospheric concentration and the indi-
vidual inhalation rate. Vapor and particle-bound pollutants are taken up
likewise. The total daily intake was related to the body weight in order
to obtain a daily inhalation dose.

Inh = Ac·Vr·AFIn
3
where Ac: PCDD/F concentrations in air (pg/m ), Vr: ventilation rate
3
(m /day), AFIn: fraction absorption inhalation (unitless).
5. Dermal absorption exposure (Ads). Dermal absorption was assumed to
occur only in case of direct skin contact to contaminated soil. People
come in contact with soil when they work outdoors or during home
gardening. Although outdoors workers are exposed during the whole year
to contaminated soil, most people are affected only a limited period of
the year because bad weather impedes the stay in their garden or they
tend to other weekend activities. Daily dermal exposure was estimated by
the following model (Table 4.5):
Ads = Sc·SA·CT·AF·Add

where Sc: PCDD/F concentrations in soil (ng/kg), SA: exposed skin sur-
2
face area (cm ), CT: contact time soil to skin (hr/day), AF: soil to skin
2
adherence factor (mg/cm ), Add: dermal absorption factor (unitless).
6. Ingestion through diet. Human daily PCDD/Fs intake from diet is calcu-
lated by multiplying the concentration of PCDD/Fs in each food group by
the amount of food group consumed daily and by the absorption fraction
(Nessel et al., 1991). Food groups were the following: meat, eggs, fish,
milk, dairy products, oil, cereals, pulses, vegetables and fruits (Table 4.6):

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