3 of 3

Write now Article Tools

It is generally accepted knowledge that the overuse of agricultural pesticides is detrimental to the environment.

Unlike natural chemicals, manufactured pesticides have long half lives, sometimes stretching for up to decades in the case of organochlorines. This means that they remain within the crop once taken up by it and are then consumed along with the crop. The levels of pesticide then start to mount within organisms, which can cause problems. This bioaccumulation of pesticides has been blamed for the reduction in many of our native farmland bird species.

The pesticide DDT can be considered a case in point. Following its development, DDT was found to be extremely efficient at killing aphids, flies, mosquitoes, the Colorado potato beetle and many other common agricultural pests. It was inexpensive to manufacture, chemically stable and tests showed that it was not very toxic to mammals.

The fact that DDT is chemically stable means that it takes a very long time to break down, a good thing for farmers as they have to spray less chemicals on their fields but, as it turned out, a bad thing for the food chain.

This was especially noticeable in the top predators. Wild populations of Peregrine Falcons were severely threatened by this build up. Once DDT had accumulated in the birds, it caused the females to lay thinly shelled eggs. Thinly shelled eggs are more likely to break, and so this had a drastic negative impact on the number of chicks hatched annually.

Once known about, this damage caused outrage amongst conservationists and the general public alike. It became such a popular issue that it even made it into music; Joni Mitchell in her song "Big Yellow Taxi" sings "Hey farmer farmer, Put away that D.D.T. now, Give me spots on my apples, But leave me the birds and the bees, Please!".

Learn more about this author, Alex Mickley.
Click here to send this author comments or questions.

Add your voice

Know something about Bio-Accumulation: Effects of spraying?
We want to hear your view. Write now!