Heptachlore is recommended for use in sugarcane. It is prohibited to other crops. But due to lack of knowledge, the farmers are using heptachlore in potato fields, wheat, vegetables, etc. The residual effect of pesticides and insecticides in fish is high as reported by the Department of Fisheries of the Bangladesh Government. A survey on 100 labourers in tea garden, revealed that after spraying the pesticides the labourers were suffering from headache,intestinal pain and vomiting tendency.
Insecticides ultimately enters the food cycle through fish, vegetables and other crops.
Scientists say that the concentration of DDT in human body in Bangladesh is 12.5 ppm which is at least five times higher than it is in the United Kingdom. Agro-hecto, Thiodan, Hildan, Hexadal are smuggled into Bangladesh from India. Scientists revealed that the toxicity of thiodan remainin soil for several years. Pesticides not only kills harmful insects, but also destroy beneficial insects, predators, bees and birds which degrades the biological diversity. Organic agriculture is still in its experimental stage.