Freedom from DDT

Published: Thursday 15 July 1999

according to Canadian scientists at the life sciences firm AstraZeneca, chicken and cow manure, old newspapers, straw and wood chips, can be used to clean up land contaminated with dangerous chlorinated pesticides such as ddt. The team came up with the alternative using local bacteria that feed on organic waste to break down hazardous substances into less harmful byproducts in a process called bioremediation. The soil bacteria convert chlorinated pesticides to less toxic byproducts by using enzymes known as dehlogenases to chop out offending chlorine groups. They hope that landowners who are liable for cleaning up tens of thousands of contaminated sites, such as old chemical plants, will adopt the technique.

The AstraZeneca researchers mixed tainted soil with large amounts of the waste to make what was a huge compost heap. The soil was tilled and aerated every few weeks, which provided both the nutrients and a cycle of alternating anaerobic and aerobic conditions for local bacteria to degrade the pesticides.

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