A particular enzyme in fish can be used as biomarker to indicate the presence of toxic and non-toxic substances, a new study has revealed.
The level of the enzyme carbonyl reductase (CBR) is elevated in the livers of fish that have been exposed to cleaned wastewater.
Scientists at the University of Gothenburg can show that CBR has properties that may make it suitable to be used as a biomarker, an early warning signal of environmental toxins.
The aim of the project is to achieve better environmental monitoring.
“While chemists measure the levels of environmental toxins, we biologists monitor their effects,” says Eva Albertsson, research student in the Department of Zoology at the University of Gothenburg.
“We can use biomarkers to discover these effects before the levels of toxins have become fatal. The increased CBR level in fish is probably caused by chemicals in the water.”
“This means that CBR may be a useful biomarker,” she added.
Our sewage treatment plants have been designed to remove nutrients from wastewater, but they are not very good at removing many other substances. Fish downstream of the treatment plants thus live in an environment that is filled with both toxic and non-toxic substances.
It is known that CBR in humans can protect against oxidative stress, which is a harmful reaction that the body activates in response to certain substances. Thus, the elevated levels of CBR we have seen in fish may not be harmful: they may act as protection.
The elevated levels, however, may be an indication that there are substances in the cleaned wastewater that cause oxidative stress, which may in the long term develop to give harmful effects.