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Toxic Substances in Food Chains!

Toxic Substances in Food Chains!. Feeding the human population is big business (effort and monetary) To prevent crops from being eaten by insects, agriculture has turned to various chemicals that kill the insects or that interfere with their life-cycle (reproduction)

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Toxic Substances in Food Chains!

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  1. Toxic Substances in Food Chains!

  2. Feeding the human population is big business (effort and monetary) • To prevent crops from being eaten by insects, agriculture has turned to various chemicals that kill the insects or that interfere with their life-cycle (reproduction) • In small doses, these chemicals are not harmful to other organisms, however, when they enter the food chains and move to high trophic levels, the quantities accumulate and can cause harm.

  3. Bio-magnification: • Accumulation of toxins in a food chain so that the major effects are found in the food predators. • Example: DDT: a pesticide used in the 50s and 60s to control populations of body lice, fleas and mosquitoes. Later used as a crop pesticide, after which sign of trouble appeared!!!!!

  4. DDT- Belugas- St. Lawrence River

  5. To Do: • Read pages 30-31 • Answer the questions on page 32.

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