Page 188 - Materials Chemistry, Second Edition

L1644_C04.fm Page 160 Tuesday, October 21, 2003 3:13 PM

Disadvantages of EUSES
• Rather complex and difficult to understand
• Data exchange/export is difficult and does not work automatically
• Sensibility/uncertainty analysis are not applicable
• Graphical visualization of the results is not implemented

4.11 CASE STUDY: APPLICATIONAL ERA TO MSWI
IN TARRAGONA, SPAIN

Consider the example of estimating risk by lifetime of a person living in the sur-
roundings of the municipal solid waste incinerator (MSWI) under study. In this
example, the methodology for estimating the distribution of daily PCDD/Fs intake
for the population living near a MSWI is presented. First, risk assessment requires
identification of the pathways through which people will be exposed to the potential
chemicals of concern, in this case PCDD/Fs. The quantitative estimation of health
noncancer and cancer risks due to a PCDD/F exposure was considered to be a
combination of six pathways: ingestion of soil, ingestion of vegetation from the area,
inhalation of resuspended soil particles, inhalation of air, dermal adsorption and
through diet. These pathways were classified depending on whether they were due
to direct deposition of the MSWI emissions or to an indirect exposure. Ingestion of
soil, ingestion of edible vegetables from the area, dermal absorption, inhalation of
resuspended particles, and air inhalation were considered pathways of direct expo-
sure, and exposure through the diet a pathway of indirect exposure.
The concentrations of PCDD/Fs were determined in soil and vegetation samples
collected near the MSWI in Tarragona, Spain (Schuhmacher et al., 1998a, b). Food
samples, which were randomly obtained from local markets and supermarkets, were
also analyzed for PCDD/Fs (Domingo et al., 1999).
We may begin by calculating the total amount of contaminant ingested via the
six different exposure pathways.

1. Ingestion of contaminated soil (Ings). Humans ingest small amounts of
soil indirectly (hand-to-mouth transfer) when they work outdoors or dur-
ing home gardening. Although outdoor workers can be exposed during
the whole year, most people have contact with soil only when they work
in their gardens. Exposure to soil is a function of the pollutant concen-
trations in soil and the individual consumption rate. Average daily dose
resulting from ingestion of contaminated soil is (Table 4.5):

Ings = Sc·SIR·AFIs

where Sc: PCDD/F concentrations in soil (ng/kg), SIR: soil ingestion rate
(mg soil/day), and AFIS: fraction absorption ingestion of soil (unitless).
SIR varies depending upon the age of the individual, amount of out-
door/indoor activity, frequency of hand-to-mouth contact and seasonal
climate (U.S. Environmental Protection Agency 1990).

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