Give the hazardous effects of agrochemicals.

Explanation

Hazardous effects of Agrochemicals :
1. Reduction in soil productivity :
(a) Most of the agrochemicals are general poisons and not specific for a particular species of pest.
(b) They kill useful pollinators and microoganisms of the soil like nitrogen fixing bacteria and cyanobacteric which can be used as biofertilisers.
(c) The natural productivity of the soil is greatly affected.
2. Resistance to pests
(a) The pests survive and become more resistant to pesticides.
(b) To control the resistant pests, greater amounts of pesticides are required which in turn increase their hazards.
3. Bioaccumulation :
(a) Many pesticides, especially organo chlorines are non-biodegradable.
(b) They persist in the environment and pollute air, water, soil and enter food chains.
(c) Being lipophilic, they get deposited in fatty tissues of organisms creating serious problems.
(d) The deposition of pesticides in fatty tissues of the host is called bioaccumulation.
4. Bioconcentration :
(a) They may pass to higher members of ecosystem through food chain.
(b) They occur in increasing concentration in top members of food chain.
(c) This is called biomagnifications or bioconcentration.
5. Health Hazards :
(a) Many pesticides are toxic in nature.
(b) The person who handles them in industries or in fields may suffer from skin diseases, blindness, respiratory diseases, nervous disorders, etc.
Example : The country's food bowl Punjab is paying the price for its productivity and a large number of cancer cases are due to excessive use of pesticides in the fields.