Lack of knowledge about the impact on natural environments

Use of pesticides in Sweden is low compared with that in many other countries, but there are large regional differences within Sweden. For example, use of pesticides in the county of Skåne makes up 50% of the total amount used in Sweden. Therefore a lower environmental impact can be expected in Sweden as a whole, but there can be a higher impact at local level. Our knowledge of the biological effects that can be caused by normal use of pesticides in the field is limited. Most of what we know about the effects of modern pesticides (pesticides designed to be easily broken down) is based on laboratory studies carried out under controlled conditions (for example a high temperature of 25°C), often with one experimental organism and one pesticide at a time. It is difficult to translate the results obtained in the laboratory to possible consequences in natural environments where a more complex system exists. In general, there are also few studies of toxicity (how poisonous a pesticide is to organisms) or of the effects of pesticide breakdown products under field conditions.

What is known is that several different pesticides are often used together within agriculture. Environmental monitoring has shown that several pesticides often occur together in agricultural streams. Two or more chemicals can sometimes interact so that the effect is more than doubled. We still know very little about how pesticides interact or, in the best case scenario, counteract each other in aquatic environments.