Understanding our Understanding our environmentenvironment

History of the Environmental History of the Environmental movementmovement

In 1939 In 1939 Paul Hermann MüllerPaul Hermann Müller discovered the insectisidal properties discovered the insectisidal properties of the chemical DDT. of the chemical DDT. – He was awarded theHe was awarded theNobel Prize in PhysiologyNobel Prize in Physiology or Medicine or Medicine in 1948 in 1948for this discovery.for this discovery.

ddichloroichloroddiphenyliphenylttrichloroethanrichloroethane (DDT)e (DDT)

Why was DDT so important?Why was DDT so important?

DDT help the allied forces win WWII.DDT help the allied forces win WWII.– The allied soldiers were dying from a The allied soldiers were dying from a

typhus outbreak.typhus outbreak.– Typhus spreads through flea bites.Typhus spreads through flea bites.– DDT was sprayed around the allied troops DDT was sprayed around the allied troops

killing the fleas that spread typhus. killing the fleas that spread typhus. DDT was sprayed on cropsDDT was sprayed on crops

– Farmers were able to get higher yields on Farmers were able to get higher yields on their crops.their crops.

Continued….Continued….

DDT eradicated malaria in the US.DDT eradicated malaria in the US.– Malaria is caused by the parasite GiardiaMalaria is caused by the parasite Giardia– Malaria is transmitted to humans via a Malaria is transmitted to humans via a

mosquito bite.mosquito bite.

Rachel CarsonRachel Carson

Marine Biologist and nature writerMarine Biologist and nature writer published the bookpublished the bookSilent Spring inSilent Spring in19621962 President Kennedy President Kennedy ordered his Science ordered his Science Advisory Committee Advisory Committee to investigate to investigate Carson's claims.Carson's claims.

Silent SpringSilent Spring

Rachel Carson blamed DDT for the Rachel Carson blamed DDT for the decline in the bird population.decline in the bird population.

Silent Spring was widely read and Silent Spring was widely read and opened peoples eyes about the opened peoples eyes about the effect humans were having on the effect humans were having on the environmentsenvironments

Cleveland’s Cuyahoga River Cleveland’s Cuyahoga River

In 1969 Cleveland'sIn 1969 Cleveland's

Cuyahoga river Cuyahoga river

was so fouled was so fouled

with industrialwith industrial

waste that it waste that it

caught on fire caught on fire

and burned.and burned.

Earth DayEarth Day

The movement was The movement was

sanctioned in April sanctioned in April

1970 with a 1970 with a

nationwide holiday, nationwide holiday,

the first "Earth Day." the first "Earth Day."

An end to DDTAn end to DDT

An end to the continued domestic An end to the continued domestic usage of the pesticide in the United usage of the pesticide in the United states was decreed on June 14, 1972.states was decreed on June 14, 1972.

World wide, DDT’s use is limited to World wide, DDT’s use is limited to countries suffering from extreme countries suffering from extreme malaria outbreaksmalaria outbreaks

But is this a good thing?But is this a good thing?

The DDT Debate:The DDT Debate:Bed Bugs are now on the riseBed Bugs are now on the rise

The DDT debate:The DDT debate:

Our intake of coffee is about 50 Our intake of coffee is about 50 times more carcinogenic than our times more carcinogenic than our intake of DDT before it was intake of DDT before it was banned...the banned...the cancercancer risk for DDT is risk for DDT is about 0.00008 per cent about 0.00008 per cent

no scientific peer-reviewed study has no scientific peer-reviewed study has ever replicated any case of negative ever replicated any case of negative human health impacts from DDT human health impacts from DDT

The debate continues….The debate continues….

widely regarded as the single most widely regarded as the single most powerful weapon at our disposal in powerful weapon at our disposal in the war against malaria the war against malaria 1.1.When Sri Lanka banned DDT in the mid When Sri Lanka banned DDT in the mid

1960s, malaria cases rose from 29 in 1960s, malaria cases rose from 29 in 1964 to more than half a million five 1964 to more than half a million five years later.years later.

2.2.Ecuador, which expanded its use of DDT Ecuador, which expanded its use of DDT in the 1980s and 1990s, experienced a 60 in the 1980s and 1990s, experienced a 60 per cent drop in infection rates.per cent drop in infection rates.

DDT in water can be absorbed by small DDT in water can be absorbed by small aquatic organisms and then concentrate aquatic organisms and then concentrate in the fish which eat these organisms. in the fish which eat these organisms.

DDT has been found in breast milk of DDT has been found in breast milk of lactating motherslactating mothers

Is thought to be responsible for the Is thought to be responsible for the decline of the American bald eagle decline of the American bald eagle through the thinning of its eggs shells.through the thinning of its eggs shells.

What are our main What are our main environmental problems?environmental problems?

Resource depletionResource depletion PollutionPollution extinctionextinction

Resource DepletionResource Depletion Natural resource –any natural Natural resource –any natural

substance that living things use.substance that living things use.

SunlightSunlight PlantsPlants

AirAir AnimalsAnimals

WaterWater ForestsForests

SoilSoil Fossil fuelsFossil fuels

MineralsMinerals

A resource is depleted when a large A resource is depleted when a large part of it has been used up.part of it has been used up.

Nonrenewable resources- resources Nonrenewable resources- resources that cannot be replacedthat cannot be replaced

Renewable resources – resources Renewable resources – resources that are continually being replaced that are continually being replaced as they are being used.as they are being used.– renewable resources can be depleted if renewable resources can be depleted if

they are being used faster then they can they are being used faster then they can be replaced.be replaced.

PollutionPollution

Pollution is the poisoning of our air, Pollution is the poisoning of our air, water, or soil.water, or soil.

Some pollutants are unintentional Some pollutants are unintentional byproducts of human activities.byproducts of human activities.

Other pollutants are toxic substances Other pollutants are toxic substances that human have intentionally that human have intentionally created such as pesticides.created such as pesticides.

ExtinctionExtinction The irreversible disappearance of a The irreversible disappearance of a

population or a speciespopulation or a species Species are disappearing faster today than Species are disappearing faster today than

at any other time in historyat any other time in history This rapid disappearance of so many This rapid disappearance of so many

species from the Earth is considered to be species from the Earth is considered to be one of the most significant environmental one of the most significant environmental challenges we face todaychallenges we face today

Most species that are becoming extinct Most species that are becoming extinct are dying because their natural homes are are dying because their natural homes are being destroyed or pollutedbeing destroyed or polluted

Endangered animalsEndangered animals