For toxicity profiling, the sample or its extract is tested in a battery of bioassays, which are biological test systems making use of whole organisms or parts of organisms (e.g., tissues, cells, proteins) showing a quantitative response when exposed to toxic chemicals. Based on the responses of the different bioassays, a toxicity profile of the sample is constructed, which can be regarded as its toxicological “fingerprint”.
Toxicity profiling can be performed for different purposes, i.e.
- To group, rank, and prioritize compounds for further research or risk assessment purposes
- To monitor environmental quality status for environmental risk assessment purposes
- To select environmental samples for further effect-directed analysis (EDA) to identify emerging, toxic compounds
The battery of bioassays ranges from in vitro bioassays (protein-binding, enzymatic, reporter gene assays) for endocrine disrupting, genotoxic, antibiotic, and neurotoxic endpoints, to in vivo zebrafish embryo assays for (neuro)developmental endpoints. Some bioassays specifically respond to compounds exerting a known mechanism of action such as receptor activation or enzyme inhibition, while other bioassays show a generic response such as respiration or growth. Current focus in the toxicity profiling theme is on the development of new bioassays and on the automation and miniaturization of existing bioassays.
MiSSE: Mixture assessment of EDC's using cats as a model for humans
HT-EDA: High-Throughput Effect-Directed Analysis
TIPTOP: Toxicity profiling of passive sampler extracts
DiPol: Transport of toxic chemicals from rivers to the coast