Anne O'Donnell: Instead of trying to build bigger, better sewage treatment plants, researcher are looking at limiting what they are putting in the water, the toxic substances. What do you think of that approach?
Dietrich Borchardt: I think that approach is necessary and innovative. It is necessary because we had to learn that these substances pass sewage treatment plants. They cannot be removed completely. And there are also other sources, for example, some of these substances are also used in agriculture and there they are released into the environment without passing through a wastewater treatment plant, via soils and groundwater. And therefore we need these approaches.
How do you avoid putting toxins in the system?
Avoiding the contamination with the substances means different things. It is the amount of substances that are applied - and then it is the tracking of these substances in the environment with monitoring systems.
Like for example what northern German scientists are doing at the moment. They are looking at creating cancer drugs that are going to be biodegradable and aren´t going to load up our water systems with chemicals so much. Do you see in the future any other chemicals or any other drugs that might go in this direction as well?
Yes, this approach has to be applied for substances that are used in large amounts; these are for example pesticides, hormones and other pharmaceutical substances which are especially effective in the aquatic environments. For those substance groups these approaches are necessary.
It is interesting that the build-up of trace substances in the water like for example hormones, namely estrogen from the pill that women take. An experiment shows an increase in the feminization of fish stocks. What is that then doing to humans if it is doing this to fish?
We have to understand these reactions of an ecosystem, with the fish stocks, as an early warning signal, because when an ecosystem reacts in an adverse way then there is an effect on the environment. And the effect is before it comes back to us humans, because we can consider our drinking water - especially in Germany - as safe, but we cannot be sure in the long run.
But essentially it builds up all the time. If we cannot ever fully eliminate hormones from the water, isn't that really in the long term something that might be very dangerous for us?
It is dangerous in these parts of the environment where these substances accumulate. Therefore we have to link approaches like this with a meaningful environmental monitoring to understand: where do we find the substances? do they accumulate or not? or are they degraded in the environment and are we safely below threshold levels that we have to consider as environmental quality standards? And we have to advance them in the same way.
Interview by Anne O'Donnell