Toxicology of Industrial Compounds

For the time being, there are only few compounds with an experimental
data base broad enough to substitute these default assumptions in every
respect. But there are important industrial chemicals—and their number
will increase eventually—for which at least some data are available for a
justified substitution of part of the default assumptions. And this should be
done as far as possible when a mathematical risk assessment is carried out.
Conclusions
Problems of classification and risk assessment have been discussed
separately for toxicological effects with thresholds (‘classical’ organ
toxicity, reproductive and developmental toxicity) and without thresholds
(mutagenicity, carcinogenicity). With regard to the general procedures of
today, for industry there are two main points of concern:
1. Not only for risk assessment but also for classification, exposure
considerations should be taken into account. In principle, there are
four different exposure scenarios: (a) for chemical production or within
chemical industry, (b) for industrial application by downstream users,
(c) for the consumer and (d) for the general population via the
environment. For a given chemical the exposure may vary widely for
the different scenarios, and there are many chemicals which are only
used within chemical industry, which will never reach the consumer or
which will enter into the environment only in minute quantities.
Exposure estimates, including worst case scenarios, should be included
in the processes of risk assessment and classification in order to avoid
over-conservative results, which are not in the interest of adequate
health protection.
2. To get away from risk assessment procedures based on default
assumptions which will often lead to over-conservative results; a case
by case approach making use of all available data is scientifically far
more appropriate.
These problems have been elaborated for the:
H.-P.GELBKE 371
– classification of chemicals for reproductive or developmental toxicity
within the regulatory framework of the EU,
– selection of appropriate ‘assessment factors’ for chemicals with
threshold effects,
– classification and risk assessment of chemicals with non-threshold
effects (especially carcinogens).