PESTICIDES! cida = "act of killing" in latin

Transcription

1 PESTICIDES! LT: I can describe the impacts of pes3cides on the environment. Cycle 2 Day classes before the AP test! cida = "act of killing" in latin

2 Primer (Intro) on Pesticides One factor that contributed to the Green Revolu-on was an increase in the use of pes3cides Pes3cides allowed for significant increases in crop survival Humans have been using pes3cides for 1000s of years Sulfur was used about 4,500 years ago in ancient Mesopotamia. Arsenic, mercury, and lead were applied to kill pests in the 15th century

3 How do Pesticides Work? You tell Liu: Why doesn t it make sense to kill agricultural pests using physical means (for example using knives, bullets)?

4 How do Pesticides Work? Most chemical pes3cides work by affec3ng the nervous system of the insect. Normally, the chemical produced by the body that sends messages between our body and our brain is called acetycholine. The pes3cide prevents acetycholine from being used by our body. This leads to paralysis.

5 A Short History of DDT DDT was not originally designed for use in farming. Originally, DDT was used in the second half of World War II to control: malaria (it killed mosquitoes) and typhus (it killed lice) among civilians and troops AFTER the war, DDT was made available for use as an agricultural insecticide, and soon its production and use skyrocketed.

6 Commons Beliefs In the 1940s, people used to be believe that DDT was: Toxic to insects and NOT to humans Broad spectrum, kills all types of insects, but relatively low risk to mammals Persistent (sticks around without degradation)

7 Commons Beliefs Toxic to insects and NOT to humans Broad spectrum, kills all types of insects, but relatively low risk to mammals Persistent (sticks around without degradation) Which of these do you think are true and which do you think are false?

8 Part A- Short Passage Instruc-ons: 1. Read and T4 the passage 2. Write a Summary In a Sentence (SIS) for each paragraph Time to complete: 6 minutes

9 Part A- Short Passage SIS for P1: SIS for P2: SIS for P3:

10 True or False Post- Reading Toxic to insects and NOT to humans (True / False) Broad spectrum, kills all types of insects, but relatively low risk to mammals (True / False) Persistent (sticks around without degradation) (True / False)

11 Part B: DDT- Let s Put it Everywhere! (3 min) Instruc-ons: As you watch the video, write down your observa-ons in the lex column and your reac-ons to those observa3ons in the right column

12 Types of Chemical Pesticides 1. Chlorinated Hydrocarbons 2. Organophosphates 3. Microbial pes3cides Add this info to the chart! Chlorinated Hydrocarbons: Example: DDT Takes a long 3me to decompose (can remain in the ecosystem for up to 15 years) Can cause convulsions, paralysis, and death They accumulate in the food chain

13 Types of Chemical Pesticides Add this info to the chart! Organophosphates: Example: Malathion Extremely toxic, but short lived (breaks down in environment) They do not accumulate in food chains S3ll used for mosquito control

14 Notes: Types of Chemical Pesticides Add this info to the chart! Microbial Pes-cides: Example: Bt Comes from bacteria or other microorganisms Not very toxic Do not accumulate in food chain Do not last long in environment Expensive

15 Bioaccumulation and BiomagniOication Bioaccumula-on - an organism absorbs a toxic substance and their bodies cannot naturally remove the substance so it stays in their 3ssues. Aka PERMANENT storage in the body! Bioaccumula3on doesn t just occur with pes3cides! Example in this picture we see an illustra3on of mercury accumula3on Biomagnifica-on: the toxic substances become more concentrated with each link in the food chain. In other words, the pes3cides that accumulate in an organism's body can then be passed on by being eaten. Famous example is DDT.

16 Case Study: DDT and Thin Eggshells During the 60s, predatory birds such as Bald Eagles suddenly disappeared from much of eastern North America. Studies revealed that eggs laid by these birds had thin, fragile shells that broke before hatching. It was found that the birds had high levels of DDT in their 3ssues.

17 Case Study: DDT and Thin Eggshells During the 60s, predatory birds such as Bald Eagles suddenly disappeared from much of eastern North America. Studies revealed that eggs laid by these birds had thin, fragile shells that broke before hatching. It was found that the birds had high levels of DDT in their 3ssues.

18 Case Study: DDT and Thin Eggshells You tell Liu: Why do you think large predatory birds were so strongly affected by DDT?

19 Part C- DDT: So Safe you Can Eat it! (1 min) Instruc-ons: As you watch the video, write down your observa-ons in the lex column and your reac-ons to those observa3ons in the right column

20 Positive and Negative Impacts to Human Society Human Health effects: Cancer, birth defects, reproduc3ve health issues, neurological problems

21 Bonus Case Study- Frog Feminization

22 Your Homework Take home all your notes from Cycle 1. The next -me I see you, bring back only: Readings (including the Cartoon readings) Notes (Guided and Cornell Notes) Quizzes (not Exit Tickets)