Page 167 - Materials Chemistry, Second Edition

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From studies of former smog pollution episodes (e.g., London smog in the
1950s), it is known that very high ambient pollution concentration is associated with
adverse health effects on the same day or on subsequent days. In the last 20 years
numerous well-conducted epidemiological* as well as experimental** studies have
confirmed this correlation between exposure to pollutants and the occurrence of
health and environmental damages. Hence, they allow establishing a direct link
between ambient concentration of certain pollutants and effects on different receptor
endpoints, as indicated in Pilkington et al. (1997) and Beer and Ricci (1999). Under
the assumption of linearity in incremental damage with incremental exposure, slope
factors (SF) could be defined. Figure 4.5 shows some possible forms of expo-
sure–response (E–R) functions as they have been found. E–R functions exist for
human health effects, damages to material and crops, and harm to ecosystems.
Unfortunately, at the moment sufficient epidemiological data are not available to
address human health effects caused by the majority of chemicals. Therefore, the
epidemiological approach must be combined with bioassays. Moreover, it should be
taken into account that epidemiological data are criticized for providing insights that
may be limited to the identification of correlations. A correlation does not necessarily
imply a causal relationship; in the case of human data from clinical studies and
trials, the causal association is considered to be higher by Crettaz et al. (2002).
According to European Commission (1995 and 2000) the E-R functions of
macro-pollutants for human health can be subdivided into the seriousness of their
effects:

response
nonlinear function

linear function

function with threshold

dose
function with fertiliser effect

FIGURE 4.5 Possible forms of exposure–response functions. (Adapted from European-Com-
mission-DGX11, ExternE — Externalities of Energy, ECSC-EC-EAEC, Brussels-Luxem-
bourg, 1995.)

* Epidemiological studies are statistical methods in which causal coherence between environmental
pollutant concentration and the occurrence of cases of illness have been thoroughly investigated.
** Experimental studies are laboratory studies with animals and in vitro, whereby safety factors are used
for the transfer of the obtained results from animal to human.

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