Toxicity and emerging contaminants – Effect-based assessment of complex environmental samples

At present, approximately 100 000 anthropogenic chemicals are in daily use and new chemicals are frequently developed. Some of these chemicals are released into the environment during their lifecycle. Currently, only a small fraction of chemicals that are present in the environment is monitored creating a so-called "tip of the iceberg" problem. Not all the chemicals that are present in the environment cause harmful effects and the challenge is to identify those chemicals that are harmful to human health and the environment. This problem is well demonstrated related to water pollution and water quality monitoring. For example, wastewater effluents contain a complex mixture of chemicals, including emerging contaminants such as hormones and pharmaceuticals, which can have toxic properties in the aquatic environment. Currently, these types of chemicals are not monitored. In this thesis, a more holistic, effect-based approach for the assessment of environmental samples is applied. Effect-based tools are sum parameter based, thus unknown chemicals, transformation products and mixture effects are taken into account. The focus of this thesis is on wastewater but aquatic environments are discussed more widely as similar approaches can be applied to different sample matrices. Influent and effluent quality of eight Finnish wastewater treatment plants (WWTPs) was investigated regarding toxicity and emerging contaminants. Removal efficiency of typical Finnish WWTPs was assessed by application of effect-based tools. These results show that the application of effect-based tools for the assessment of complex environmental samples, such as wastewaters or sediments, can provide valuable information that is not achieved with current methods for monitoring. The results indicate that bioassay batteries for water quality assessment should include a large variety of assays covering multiple endpoints and test organisms. Based on the results, estrogenic activity, thyroid disruption, and embryotoxicity are relevant endpoints related to the assessment of wastewater quality. Effluents may also cause adverse effects on fish embryos or induce genotoxic effects. The results demonstrate that the removal of emerging contaminants and toxicity is incomplete with conventional treatment methods. More advanced treatment methods are needed to further improve water quality and control the discharge of chemicals to our environment. Overall, application of effect-based tools together with chemical analysis will help us achieve a safer environment and higher quality of monitoring.