technical guidance documents - Institute for Health and Consumer ...

GENERAL INTRODUCTION
countries in the European Union. It is recognised, however, that exposure estimation, for
example, is subject to variation due to topographical and climatological variability. Therefore, in
this document in the first stage of the exposure assessment where exposure models are used, socalled
generic exposure scenarios are applied. These assume that substances are emitted into a
non-existing model environment with predefined agreed environmental characteristics. These
environmental characteristics can be average values or reasonable worst-case values depending
on the parameter in question. Generic exposure scenarios have been defined for local emissions
from a point source and for emissions into a larger region. In these generic scenarios emissions
to lakes are not assessed. When more specific information on the emission of a substance is
available, it may well be possible to refine the generic or site-specific assessment.
Chapter 7 (Part IV) contains for a number of use categories so-called emission scenario
documents (ESDs) that give more specific information on emissions to the environmental
compartments that can occur during the use of a substance. Chapter 7 includes ESDs for some
types of application of biocides while scenarios describing emissions of biocides from other
processes are still being developed. Such scenarios allow for quantitative emission estimation,
which is an important first step in the exposure assessment, and generally has a significant
influence on the outcome of risk assessments.
While comprehensive risk assessment schemes are presented for the aquatic and the terrestrial
compartment and for secondary poisoning, allowing a quantitative evaluation of the risk for
these compartments, the risk assessment for the air compartment can normally only be carried
out qualitatively because no standardised biotic testing systems are available at present. It should
also be noted that the schemes for the sediment and terrestrial compartments and for secondary
poisoning are currently not supported by the same level of experience and validation as available
for the aquatic compartment. These schemes will need to be further reviewed and, if necessary,
revised when new scientific knowledge and experience becomes available.
The test and assessment strategies in this Technical Guidance Document are based on the current
scientific knowledge and the experience of the competent authorities of the Member States. In
this way, they reflect the best available scientific information to date and make use of the limited
data set usually available. However, because this data set is limited, in particular for new and
existing substances where the data sets are restricted to acute toxicity testing with only three
trophic levels, there may be effects of substances that are not so well characterised in the
assessment, such as:
• Adverse effects for which no adequate testing strategy is available yet (e.g. neurotoxicity,
behavioural effects and endocrine disrupting effects);
• Specific effects in some taxa that cannot be modelled by extrapolation of the data of other
taxa (for example the specific effect of organotin compounds on molluscs).
For some substances the information on the environmental release from certain stages of the lifecycle,
which may include the presence of the substance in preparations, is so scarce that the PEC
is quite uncertain or even not possible to estimate quantitatively. In the latter case a qualitative
risk assessment is conducted (see Section 5.6).
9