Have read a book long ago, called "Silent Spring" by a woman whose name I cannot recall. The book referred to the use of D.D.T. and how it infected the wildlife and got into the rivers and streams. This was during the 50s. when we lived at Leicester and saw some dead fish in the river soar.
So little is mention about farmers using chemicals today, but there seems to be less wildlife about.

DDT WAS THE BE ALL TO END ALL BUG KILEER. ITIT WAS SPRAYED ON CROPS REPEATEDLY, THEN LO AND BEHOLD IT WAS BANNED, IT WAS FOUND TO BE KILLING WILDLIFE, AND AS FAR AS I UNDERSTAND IT WAS ALSO GETTING INTO THE FOOD CHAIN.WE HEAR OF SUCH A LOT OF CANCER CASES THESE DAYS, I OF TEN WONDER IF THERE IS ANY CONNECTION.WE SHALL NEVER KNOW.

No one would admit it, even if it happened, it does make you wonder though how do they know it isn't still around in our soil and waterways.