Pesticide, Bioaccumulation and Biomagnification

Brainstorm the pros and cons of pesticide on whiteboard

Pesticides- Pros and Cons?Cons

1. Mutation randomly occur allows pest to develop resistance to pesticides

2. Costs lots of time and resources to constantly develop new poisons

3. They are often toxic substances and can accumulate and magnify in the food chain

Pros1. Protect, thus protecting industries’ and farmers’ profits

2. Prevent epidemic outbreak

What are pesticides?- are chemicals that kill pests- 2.3 million tonnes of pesticides used yearly

- 75% used in agriculture

Bioaccumulation

refers to an increase in the concentration of a chemical in an organism over time.

Bioaccumulation vs Biomagnification (of toxin e.g. pesticides)

Biomagnification (also bioamplification) is the increase concentration of toxic chemicals, such as pesticides as it is passed upwards and maximized to the top predator of the food chain

DDT- a dangerous pesticide

a DDT molecule

DDT:(stands for Dichlorodiphenyltrichloroethane) 

- First produced in 1939-a highly potent, fat soluble insecticides

Case study 1: DDT and the bald eagle

Bald eagles feed on fishThey disappear for many reasons:- Loss of habitat (industrialization, deforestation)- Hunting- Toxins in lakein lake

DDT in the Great LakesHow DDT enter the Great Lakes?- In this food chain, what type of consumer is the bald eagle?- tertiary (top) consumer- How could DDT end up in the bald eagle with highest concentration?

Impacts of DDT on birds

double-crested cormorant

Egg shell thinning

DDT was banned in Canada in 1971

Discussion

There still countries haven’t banned DDT. Why would this be of concern to Canadians?

Breast milk contains fat. How breast-feeding might affect the concentration of DDT in a mother and in her baby?

Mercury Poisoning- Minamata diseasehttps://www.youtube.com/watch?v=oxB_SXbxY28

Choose the most correct statement(s)

a.The residents of Minamata have bioaccummulated mercury in their body

b.The residents of Minamata have biomagnified mercury in their body

c.The residents of Minamata display both bioaccummulation and biomagnification

d.The residents of Minamata have also suffered from lead poisoning

Mercury Poisoning- Minamata diseasehttps://www.youtube.com/watch?v=oxB_SXbxY28

Choose the most correct statement(s)

a.The residents of Minamata have bioaccummulated mercury in their body

b.The residents of Minamata have biomagnified mercury in their body

c.The residents of Minamata display both bioaccummulation and biomagnification

d.The residents of Minamata have also suffered from lead poisoning

You are what you eat

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