Risk assessment of transformation products
In
today’s practice of authorization and regulation of chemicals (pesticides, biocides,
pharmaceuticals) as well as in the evaluation of water quality criteria the
center stage is still taken by the originally used chemicals (parent
compounds). However, less persistent chemicals will be abiotically or
biotically degraded in the environment without being fully mineralized in each
case. These emerging transformation products are quite often more persistent
and more polar and can therefore reach the aquatic environment more easily than
the parent compounds. In some cases the transformation products are even
similarly toxic or even more toxic than the parent compound
(Figure 1).
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Figure 1 A parent compound with specific mode of action can be degraded to a compound, which 1) contains a new toxicophore or 2) loses its specific mode of action and is now baseline toxic. Or 3) a parent compound that already is a baseline toxicant undergoes changes in hydrohpobicity and typically loses some of its toxic potency. |
One of the main goals of our work is to systematize the ecotoxicological risk assessment for transformation products. Therefore, we use different biotests and Quantitative Structure-Activity Relationships (QSARs), which correlate the toxicity of compounds with their chemical properties, to gain additional information about the toxic properties of transformation products.
In our recent projects we focus on answering the following questions:
- Which processes (oxidative/photochemical) are most efficient in removing the toxicity of parent compounds and which patterns lead to formation of toxic intermediates?
- How does transformation influence the mode of toxic action of parent compounds?
- How does toxicity evolve if a mixture of parent compound and its transformation products is present?
- How can we assess the hazard transformation products pose to the aquatic environment?
- Which transformation products are relevant because of their effects?
- How can transformation products be
implemented in the authorization and risk assessment process of chemicals and
which models are helpful tools?
Projects
- KoMet: Combined methods to measure and model transformation products in the aquatic environment
- ToxMet: Toxicity of Metabolites formed under light and during oxidative processes (joint project with Department Water Resources and Drinking Water)