Page 171 - Materials Chemistry, Second Edition

L1644_C04.fm Page 143 Tuesday, October 21, 2003 3:13 PM

For example, the additional REW by NO are calculated in the following way
x
for imaginative values of ∆c/, C , and A :
CL
EE
f = 0.00082 (µg/m )/ FU/ 100 µg/m = 0.0000082/ FU
3
3
RE
2
REW = 0.0000082/ FU * 10,000 km = 0.082 km / FU
2
where ∆c = 0.00082 (µg/m ) concentration increase/ functional unit (FU)
3
C = 100 µg/m (concentration corresponding to critical load)
3
CL
A = 10,000 km (ecosystem exceeded area)
2
EE
Moreover, damage functions exist for environmental damage on crops and mate-
rial, as what in the present is defined as the AoP man-made environment. There are
two basic pathways through which plants can be harmed by SO . The first is through
2
foliar uptake of pollutants, and the second through effects of acid deposition on the
soil. Damages to material refers to surface damage, especially in buildings, bridges
and cars, due to acidic deposition. However, not included are cultural damages, e.g.,
to ancient cathedrals, due to their intrinsic value as mankind’s patrimony.

4.7 RISK CHARACTERIZATION AND CONSEQUENCE
DETERMINATION

The last stage of the risk assessment process, risk characterization, involves a
prediction of the probability and severity of health and ecological impact in the
exposed population and environmental damages. That is, the information from the
dose–response evaluation (What human dose or PEC is necessary to cause an effect?)
is combined with the information from the exposure assessment (What human dose
or PEC is the population or ecosystem receiving?) to produce an estimate of the
likelihood of observing an effect in the population or ecosystem being studied. An
adequate characterization of risks from hazards associated with environmental con-
tamination problems allows risk management and corrective action decisions to be
better focused. To the extent feasible, risk characterization should include the dis-
tribution of risk among the target populations.

4.7.1 HUMAN HEALTH RISK
Human health risk characterization is the estimation of whether adverse effects are
likely to affect humans who are exposed to certain substances. This process includes
the comparison of the hazard and dose–response information, usually derived from
animal experiments or in vitro test systems, with data on human exposure levels, as
has been explained before. For notified new substances, risk characterization should
take account of each adverse effect for which the substances have been assigned a
hazard classification, together with any other effect of possible concern. Workers,
consumers and humans exposed indirectly via the environment must be considered.

© 2004 CRC Press LLC