Environmental Toxicology

Modeling and understanding the joint effect of chemical mixtures

The joint effect of most chemical mixtures can be well predicted by mathematical models. A few, however, deviate from the predictions and yield much larger effects than could be expected from knowing the toxicity of the individual chemicals. These mixtures are called synergistic.

In the research group we work towards an understanding of the mechanisms behind some of these synergistic mixtures. We do this by investigating the toxicokinetics (uptake, metabolisation and excretion overtime) and toxicodynamics (effects over time) of the chemicals alone and in mixtures while measuring activity of suspected target enzymes.

Our research is presently focused on mixtures of azole fungicides and pyrethroid insecticides, which are sprayed out together in agricultural pest management and known to co-occur in the environment. The aim is to be able to predict environmental effects of these mixtures and assess the importance of the synergistic interactions under natural conditions.

The work is financed by the University of Copenhagen and takes place in collaboration with University of Cambridge.

Watch Professor Nina Cedergreen in the video: "Chemical Cocktails"

Interactions between chemicals and other stress factors

The severity of chemical intoxication will depend on the living conditions of the organism. Both directly through the capacity to take up, metabolize excrete as well as adapt to the chemicals, but also indirectly, as environmental parameters such as humidity, pH, substrate composition and temperature, will affect the bioavailability of chemicals through effects on sorption, speciation, leaching, speed of degradation etc.

We investigate the interactions between chemicals and the occurrence of natural nano-particles and dissolved organic substances on uptake of chemicals in different aquatic invertebrates ranging from crustaceans, and insect larvae to worms and snails. Additionally, we study adaptation and transgenerational effects of chemical exposure in Daphnia magna. In another project we work in collaboration with Section of Organismal Biology to investigate the effects of two types of parasites; a tape worm and a pathogenic fungi, on uptake and metabolisation capacity of different pesticides in a beetle model insect. The aim is to elucidate and quantify the interactions between sublethal pesticide intoxications and parasite infections, and to understand the physiological mechanisms govering the interactions.

The work is financed by the Danish Environmental Agency and the Villum Kant foundation and includes close collaborations with University of York.

The toxicity of natural bioactive compounds

Bioactive compounds produced by plants or microorganisms can be just as toxic as any antropogenically-produced chemical. They are, however, rarely regulated to the same extend as industrially produced chemicals. Presently we work with saponin rich plant extracts approved as “biopesticides” in the U.S. and used for a range of purposes in the environment.

We investigate the fate and ecotoxicity of selected natural compounds suspected to cause adverse environmental effects and compare them to known industrially produced chemicals such as pesticides and pharmaceuticals. The aim is to elucidate whether these naturally produced compounds cause adverse environmental effects and to give guidance to how these effects can be mitigated.

The research is financed by the Chinese Scolarship Council.

• ENSAFE - ENvironmental SAFEty of Biotechnological Plant Protection Products
• VANDALF - Linking of Chemical and Toxicological Fingerprints: A new method to prioritize monitoring and regulation of pollutants in water (WP-lead)
• AQUAPLEXUS (WP-lead)
• Contaminomics (WP-lead)
• QTOX (WP-lead and two PhDs)
• Phishes
• KNOWPEC - Knowledge for pesticide control