By: Michelle DAlleva, Chris Reyes
and Winnie Tema
Chapter 14 Overview
• What causes cancer in Humans and
Animals?
• How do pesticides pollute the environment
and their effect?
• How do pesticides and other chemicals
affect the environment and the organisms
living with in them?
Battle of Living Things against
Cancer.
Natural hazards
Man-made hazards
•Ultraviolet radiation in
sunlight causing skin cancers
•Arsenic washed out of soil
or rocks contaminating food
and water supplies
•CARCINOGENS
•Arsenic, in sodium arsenite- a weed killer
•DDT
•CFC’s- which deplete the ozone layer
Ozone Depletion
•Lethal form of skin cancer and cataracts
will become common.
•Unpredictable effects on crops, our food
source.
Contamination
•
•
An arsenic contaminated environment
affects not only man but animals as
well.
Report from Germany in 1936 after
arsenic fumes were let out into the air:
1. Settled down on vegetation
2. Horses, cows, goats, and
pigs, that fed upon this
vegetation showed loss of
hair and thickening of skin.
3. Arsenic was found in the
dead animals brain, liver and
tumors.
4. High mortality for insects
5. Then it rains and the arsenic
is washed into the streams
and carried to the marine
systems, where it kills all the
fish.
DDT Effects
• Humans release many different toxic chemicals into the environment,
without understanding the ecological effect.
• Once the toxins are consumed by organisms they accumulate in
specific tissues.(FAT)
• Therefore when that organism is consumed by another organism, the
toxin become more concentrated in successive trophic levels of a food
web = BIOLOGICAL MAGINIFACTION.
• Magnification occurs because the biomass at any given trophic level is
produced from a much larger biomass ingested from the level below.
 top level predators are the most severely harmed. = HUMANS
•
•
•
The rise in use of modern pesticides has led to an increase in the incidence of Leukemia.
All Leukemia patients had a history of exposure to various toxic chemicals, including sprays
which contain DDT, chlordane, benzene, lindane and petroleum distillates.
There seems to be a “cause-and-effect relationships between these chemicals and leukemia
and other blood disorders.
Theories on the Origin of Cancer Cells
• German biochemist- Professor Otto Warburg theorized that either recitation or a chemical
carcinogen acts by destroying the respiration of normal cells, therefore depriving them of energy.
• the cells can no longer carry on the high energy producing cycle of ATP production and
have to start undergoing a less effective method – fermentation.
•When the cells reach a point where they can produce as much energy from fermentation that they
could from respiration- at this point the cells are classified as CANCER CELLS.
Chapter 15 vs. Chapter 50-54
• Our chemical attack is weakening the defenses inherent in
the environment itself. Defenses designed to keep the
various species in check. Each time we breach these
defenses, a horde of insects pours through
• New problems rise as insects once present only in
insignificant numbers had increased to the status of serious
pests. By their very nature, chemical controls are selfdefending, for they have been devised and applied without
taking into account the complex biological systems against
which they have been blindly hurled.
• The balance of nature is not the same toy as in Pleistocene
times, but it is still there: a complex, precise and highly
integrated system of relationships between living things
which cannot safely be ignored anymore that the law of
gravity can be defied with impunity by a man perched on
the edge of a cliff.
• Populations are kept in check by something ecologists call
the assistance of the environment, and this has been so
since the first life was created. The amount of food
available, conditions of weather and climate, the presence
of competing predatory species, all are critically important.
• Second neglected fact is the power of a species to
reproduce once the resistance of the environment has been
weakened.
• At one point, a deer population was in equilibrium with its
environment. However, the number of predators prevented
the deer from out-running their food supply
• Deer increased prodigiously and soon there was not
enough food for them. Deer dying of starvation, then
formerly been killed by predators. The whole
environment, was damaged by their desperate efforts to
find food.
• The vast majority of these insects are held in check by
natural forces without any intervention of man
• Volume of chemicals could possibly keep down their
population
• The predators are of many kinds. Some are quick and with
the speed of swallows, snatch their prey from the air.
Others plod methodically along a stem, plucking off and
devouring sedentary insects like the aphids
• Predators have found ways to tide themselves over the cold
season
• While reasonably effective against the target
insects, has let loose a whole Pandora’s box of
destructive pests that have never been previously
abundant enough to cause trouble.
• In 1956, the US Forest Service sprayed 885,000
acres of forested lands with DDT.
• Nature is kept in check by various predators
• Far greater abundance of space and food was
available in former colonies