1. Pesticides

2. What ARE They?

3. Pesticides Pesticides are chemicals that kill unwanted organisms, usually those that attack crops. Therefore, they are intended to help us by killing the species we don’t want. They affect many processes of living things: Growth Growth Reproduction Reproduction Neurological Development Neurological Development Immune System Immune System

4. Why are they BAD for the environment?

5. They remain in the environment for a long time, and often kill much more than what they are “intended” to kill When humans first started to use pesticides

6. Bioaccumulation & Biomagnification When substances (like pesticides) build up in an organism’s body throughout its lifetime, this is called bioaccumulation. As we move up a food chain, a pesticide becomes more and more concentrated. This is known as biomagnification.

7. Biomagnification When humans use pesticides, goes into abiotic components of the ecosystem (e.g. water, soil). It starts here in low concentration. The producers that live in water or soil absorb these toxins into their bodies. When the primary consumers eat the producers, they are also eating the toxins, and the toxins accumulate in their body. Every trophic level has a higher concentration of toxins, making it fatal.

8. How do pesticides affect humans? As you have been learning throughout this course, we are very connected to ecosystems. Think about the food we eat… how is it possible that it contains toxins from pesticides? Video: http://youtu.be/aTm7i84mcMI Note that this video is from Europe, and they have stricter rules about pesticide use that we do

9. DDT DDT (dichlorodiphenyltrichloroethane) was a pesticide used in Canada and throughout the world up until 1970. It was considered a miracle chemical because it killed insects that spread diseases and ruined crops. It was considered safe for humans because there were no short-term toxic effects Therefore, it was applied to everything in mass quantities.

10. Dangers of DDT In 1962, conservationist Rachel Carson wrote a book, Silent Spring, warning of the dangers of using pesticides such as DDT. She warned that pesticides kill species in ecosystems and would also affect human health. Her book changed people’s attitudes towards the environment Throughout the 1960’s, most people realized these dangers as DDT caused a huge amount of devastation because it would accumulate in top consumers The peregrine Falcon almost became extinct because of DDT

11. Mallard Duck Eggs Affected by DDT The DDT causes the eggs laid by many different birds to have soft shells that crack. The baby birds then die before they hatch.

12. Consumption of DDT  While microorganisms are affected by DDT, many tend to keep it inside of them rather than dying immediately (bioaccumulation)  This causes a chain reaction, up the food chains they are in (biomagnification)  Likewise, many small creatures on land (ex. Earthworms) can accumulate DDT in their systems, which is harmful to predators that eat them

13. Effects of DDT  In birds, DDT causes the thinning of eggshells.  Humans can also accumulate DDT in their bodies, where it is stored in fatty organs and can be harmful to bodily functions  Results: dizziness, seizures, respiratory illness, and immune system dysfunction

14. The DDT ban Since the 1970s, DDT was banned in North America. Since 2001, most other countries in the world agreed to ban it. DDT is still used in some regions, such as Africa, to kill mosquitoes that spread the disease Malaria Some argue that the Malaria kills more humans than the DDT, so they would rather be exposed to DDT. Therefore, they still use DDT, but in small quantities. Banning DDT has been blamed for the increase of other insects too, such as bed bugs

15. Video: http://youtu.be/kyYpwOTtaLIhttp://youtu.be/kyYpwOTtaLI Considering the benefits of DDT, do you think it is justifiable to still use it?

16. Homework p. 80 #5 p. 85 #9, 10