Pesticides in a historical perspective

'Modern' pesticides increase the risk to the aquatic environment

In Sweden and other EU countries, the most dangerous and persistent substances have been replaced by substances that are broken down more easily and are therefore not present in the environment for such a long time. However, even the old substances can persist for a long time if they end up in a soil or sediment with a low temperature, oxygen-deficient conditions and low microbial activity. It is not uncommon for the ‘modern’ substances to have a higher acute toxicity than many of the older, more slowly degradable pesticides, for example DDT.

This is mainly because the modern pesticides have a more specific mechanism of action against their target organisms and can be applied in lower doses. The advantage is that a smaller amount of the substance can be used to treat the same area, but the compounds can also cause great damage if they reach environments where organisms other than the target object are exposed. For example, aquatic organisms can be very sensitive even at low concentrations.