Understanding our environment

History of the Environmental movement In 1939 Paul Hermann Müller discovered the insectisidal properties of the chemical DDT. He was awarded the Nobel Prize in Physiology or Medicine in 1948 for this discovery.

dichlorodiphenyltrichloroethane (DDT)

Why was DDT so important? DDT help the allied forces win WWII. The allied soldiers were dying from a typhus outbreak. Typhus spreads through flea bites. DDT was sprayed around the allied troops killing the fleas that spread typhus. DDT was sprayed on crops Farmers were able to get higher yields on their crops.

Continued…. DDT eradicated malaria in the US. Malaria is caused by the parasite Giardia Malaria is transmitted to humans via a mosquito bite.

Rachel Carson Marine Biologist and nature writer published the book Silent Spring in 1962 President Kennedy ordered his Science Advisory Committee to investigate Carson's claims.

Silent Spring Rachel Carson blamed DDT for the decline in the bird population. Silent Spring was widely read and opened peoples eyes about the effect humans were having on the environments

Cleveland’s Cuyahoga River In 1969 Cleveland's Cuyahoga river was so fouled with industrial waste that it caught on fire and burned.

Earth Day The movement was sanctioned in April 1970 with a nationwide holiday, the first "Earth Day."

An end to DDT An end to the continued domestic usage of the pesticide in the United states was decreed on June 14, 1972. World wide, DDT’s use is limited to countries suffering from extreme malaria outbreaks But is this a good thing?

The DDT Debate: Bed Bugs are now on the rise

The DDT debate: Our intake of coffee is about 50 times more carcinogenic than our intake of DDT before it was banned...the cancer risk for DDT is about 0.00008 per cent no scientific peer-reviewed study has ever replicated any case of negative human health impacts from DDT

The debate continues…. widely regarded as the single most powerful weapon at our disposal in the war against malaria 1.When Sri Lanka banned DDT in the mid 1960s, malaria cases rose from 29 in 1964 to more than half a million five years later. 2.Ecuador, which expanded its use of DDT in the 1980s and 1990s, experienced a 60 per cent drop in infection rates.

DDT in water can be absorbed by small aquatic organisms and then concentrate in the fish which eat these organisms. DDT has been found in breast milk of lactating mothers Is thought to be responsible for the decline of the American bald eagle through the thinning of its eggs shells.

What are our main environmental problems? Resource depletion Pollution extinction

Resource Depletion Natural resource –any natural substance that living things use. Sunlight Plants Air Animals Water Forests Soil Fossil fuels Minerals A resource is depleted when a large part of it has been used up.

Nonrenewable resources- resources that cannot be replaced Renewable resources – resources that are continually being replaced as they are being used. renewable resources can be depleted if they are being used faster then they can be replaced.

Pollution Pollution is the poisoning of our air, water, or soil. Some pollutants are unintentional byproducts of human activities. Other pollutants are toxic substances that human have intentionally created such as pesticides.

Extinction The irreversible disappearance of a population or a species Species are disappearing faster today than at any other time in history This rapid disappearance of so many species from the Earth is considered to be one of the most significant environmental challenges we face today Most species that are becoming extinct are dying because their natural homes are being destroyed or polluted

Endangered animals