What is `bioaccumulation of pesticides and why is it a concern?
Pesticides can become concentrated, perhaps to toxic levels, via the food chain. Thus, an insect feeding on plant sprayed with pesticides might be eaten by another insect which might then be eaten by a bird. This is especially a problem with pesticides that are fat-soluble and highly persistent, including DDT and other organochlorines. Traces of pesticides too small to kill the targeted pest can accumulate to levels high enough to harm species further on up the food chain. In the early 1970s, hundreds of people in South India – all poor and of low caste ? were afflicted with a mysterious, painfully crippling disease. Investigations finally determined that the condition was caused by eating pesticide-contaminated crabs scavenged from sprayed rice fields. • Don’t pesticides usually disappear once they are applied? Many pesticides do break down rapidly in the environment, but others – like DDT and dieldrin – can remain toxic for 20 years or longer, continuing to kill insects and harm othe
