Page 193 - Materials Chemistry, Second Edition

L1644_C04.fm Page 165 Tuesday, October 21, 2003 3:13 PM

TABLE 4.9
Parameter Values for PCDD/Fs
Parameter Symbol Units Value References

Body weight BW kg 67.52 —
Noncarcinogenic NCP pg/kg/day 1–4 Van Leeuwen et al. (2000)
potency factor
Carcinogenic CP (mg/kg/day) –1 34,000–56,000 Katsumata and
potency factor Kastenberg (1997)

TABLE 4.10
Noncarcinogenic and Cancer Risks by Direct Diet, Direct Risk and
Total Exposure

Noncarcinogenic Carcinogenic
Direct risk 8.04 × 10 –3 Direct risk 8.64 × 10 –7
Diet risk 6.79 × 10 –1 Diet risk 7.31 × 10 –5
Total exposure 6.87 × 10 –1 Total exposure 7.39 × 10 –5

–5
The total cancer risk is 7.39 × 10 , which means that a person living in the
surroundings of the MSWI has chance of less than one in a million of developing
cancer during his or her lifetime. The total noncancer risk is 6.87 × 10 , which
–1
means that the population exposure does not exceed the threshold value. Neither the
emissions from the MSWI nor the indirect exposure (diet) to PCDD/Fs in the
Tarragona area would mean an additional noncarcinogenic risk for health to general
population living in the area.
Another point is that, in both cases (noncarcinogenic and carcinogenic risk), the
total risk is due mainly to diet. Consequently, under the present conditions, Tarrag-
ona’s MSWI would not cause a substantial additional exposure to PCDD/Fs in the
area under potential influence of the plant. See Table 4.9.

4.12 QUESTIONS AND EXERCISES

1. Indicate possible and ideal target/indicator species for an ERA in the
following cases: a) dioxins emission of a MSWI; b) acid rain; c) indoor
radiation. Explain their advantages and disadvantages.
2. Which aspects do you consider the main difficulties in the selection of
target species of an ecosystem to overall risk assessment? How do you
consider these problems can be noticeably improved?
3. Describe the main concept of risk assessment and sum up the main fields
and boundaries of application as well as the main tools utilized in it.

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