endocrine disruptors and ddt
DESCRIPTION
VCE Environmental Science - Unit 4: Pollution. The sources, sinks, human and environmental health effects of DDT and endocrine disruptors, including pthalates, are discussed in this presentation.TRANSCRIPT
- 1. Endocrine Disruptors, Phthalates and DDT
VCE Environmental Science: Unit 4
Area of Study 1: Pollution
2. Last week Air Pollution What do you remember?
3. Sulphur dioxide What do you remember?
4. Endocrine Disruptors
Endocrine disruptors are chemicals that interfere with endocrine
(or hormone system) in animals, including humans. These disruptions
can cause cancerous tumours, birth defects, and other developmental
disorders.Known endocrine disrupting chemicals include:
Pesticides (such as DDT)
PCBs
Bisphenol A (BPA)
Polybrominateddiphenyl ethers (PBDE)
Pthalates and Alkylphenols
5. http://www.nacsetac.org/Shortcourse/shortcourse_2011.htm
6. Endocrine Disruptors
The critical period of development for most organisms is between
the transition from a fertilized egg, into a fully formed
infant.
As the cells begin to grow and differentiate, there are critical
balances of hormones and protein changes that must occur.
Therefore, a dose of disrupting chemicals can do substantial damage
to a developing fetus (baby). Whereas, the same dose may not
significantly affect adult mothers.
http://www.endocrine-disruptors.net/about_endocrine_disruptors.html
7. Human Health Effects
Specifically, they are known to cause learning disabilities, severe
attention deficit disorder cognitive and brain development
problems, deformations of the body (including limbs); sexual
development problems, feminizing of males or masculine effects on
females.
8.
http://www.niehs.nih.gov/news/newsletter/2009/july/extramural-update.cfm
9. PCBs
Polychlorinated biphenyls are a class of organic compounds with 2
to 10 chlorineatoms attached to biphenyl, which is a molecule
composed of two benzene rings.
Concerns about the toxicity of PCBs are largely based on compounds
within this group that share a structural similarity and toxic mode
of action with dioxin.
Were used in transformers,capacitors,plasticizers, flame
retardants, sealants and coolants now banned.
10. Dichlorodiphenyltrichloroethane
DDT was first synthesized in 1874, but its insecticidal properties
were not discovered until 1939. It was used with great success in
the second half of World War II to control malaria and typhus among
civilians and troops.
After the war, DDT was made available for use as an agricultural
insecticide and soon its production and use skyrocketed.
11. Farm workersin Central Valley being
sprayed with pure DDT in 1956.
12. Silent Spring by Rachel Carson
In 1962, Silent Spring by American biologist Rachel Carson was
published. The book catalogued the environmental impacts of the
indiscriminate spraying of DDT in the US and questioned the logic
of releasing large amounts of chemicals into the environment
without fully understanding their effects on ecology or human
health.
The book suggested that DDT and other pesticides may cause cancer
and that their agricultural use was a threat to wildlife,
particularly birds.
Its publication was one of the signature events in the birth of the
environmental movement, and resulted in a large public outcry that
eventually led to DDT being banned in the US in 1972
13. Persistence in soil
DDT is a persistent organic pollutant that is extremely hydrophobic
and strongly absorbed by soil. Depending on conditions, its soil
half-life can range from 22 days to 30 years.
Routes of loss and degradation include runoff, volatilization,
photolysis and aerobic and anaerobic biodegradation.
14. Persistence in water
When applied to aquatic ecosystems it is quickly absorbed by
organisms and by soil or it evaporates, leaving little DDT
dissolved in the water itself.
Its breakdown products and metabolites, DDE and DDD, are also
highly persistent and have similar chemical and physical
properties
15. Effects on Vertebrates
DDT is toxic to a wide range of animals in addition to insects,
including marine animals such as crayfish and prawns and many
species of fish.
It is less toxic to mammals, but may be moderately toxic to some
amphibian species, especially in the larval stage.
DDT and DDE have been linked to diabetes, neurological problems,
cancer and decreased fertility in males.
16. Effect on Birds
Most famously, it is a reproductive toxicant for certain birds
species, and it is a major reason for the decline of the bald
eagle, brown pelican, peregrine falcon and osprey.
Birds of prey, waterfowl and song birds are more susceptible to
eggshell thinning than chickens and related species, and DDE
appears to be more potent than DDT.
17. 18.
http://www.dolphinwatchnaturetours.com/edres/images/DDT.jpg
19. Pthalates
Phthalates (pronounced THAL-ates) are the most commonly used
plasticisers in the world, and have been in use for about 50 years.
They are primarily used to make polyvinyl chloride (PVC) flexible,
but this group of industrial chemicals is used to confer softness,
viscosity, transparency, flexibility and durability to a range of
products including:
Toys and food packaging,
Erasers and hoses
Raincoats and shower curtains,
Vinyl flooring and wall coverings,
Pigments, lubricants, adhesives and wood finishes,
Gelling and emulsifying agents,
Waxes, solvents and detergents,
Pesticides
Medical products including catheters and transfusion devises.
Nail polish, perfume, moisturisers, hair spray and shampoo
20. Characteristics of Pthalates
Phthalates are a family of organic chemical substances produced
from petroleum. They are esters of phthalic acid which are widely
used as industrial compounds. When added to plastics, phthalates
allow the long polyvinyl molecules to slide against one another.
They are produced by reacting phthalic anhydride with an
appropriate alcohol. Phthalates have:
low water solubility
high oil solubility
low volatility
colourless
odourless
liquids
21. Impacts of Pthalates:
There have been a number of studies into the health impacts of
phthalates.
Some studies suggest they have a number of health impacts,
including disrupting the endocrine system.
Phthalates is one group of endocrine disrupting chemicals (EDCs)
that affect the bodys hormones.
The endocrine system is important in controlling hormones, which in
turn balance several systems in the body including the reproductive
system.
22. Impacts of Pthalates:
As of 2004, manufacturers produced about 363 thousand metric tonnes
of phthalates each year. By weight, they contribute 10-60% of
plastic products.
Phthalates can act as an oestrogen mimic, though knowledge of their
impacts is still is slowly accruing.
There is also considerable debate regarding their impacts, as
different studies have arrived at conflicting conclusions, and
while there has been some studies suggesting they pose considerable
danger to some laboratory animals, there is debate as to whether
this information can be extrapolated to humans.
23. Impacts of Pthalates:
Some of the impacts attributed to phthalates include:
premature births
reduced sperm counts
structural abnormalities in the reproductive organs of male test
animals
liver cancer
There has also been speculation they may cause:
susceptibility to allergens
premature breast development in young girls
obesity and diabetes
24. Impacts of Pthalates:
Although an expert panel has concluded that there is "insufficient
evidence" that they can harm the reproductive system of infants,
the state of California and the Europe Union have banned them from
toys. In 2002, the US Food and Drug Administration (FDA) released a
public report which cautioned against exposing male babies to DBP
and DEHP. Although there are no direct human studies the FDA report
states:
Exposure to DEHP has produced a range of adverse effects in
laboratory animals, but of greatest concern are effects on the
development of the male reproductive system and production of
normal sperm in young animals. We have not received reports of
these adverse events in humans, but there have been no studies to
rule them out. However, in view of the available animal data,
precautions should be taken to limit the exposure of the developing
male to DEHP".
25. Transport mechanisms and sinks
Phthalates are easily released into the environment because they
can easily leach and evaporate into food, water or the atmosphere.
As plastics age and break down, the release of phthalates
accelerates. Phthalates in the environment are subject to
biodegradation, photo-degradation, and anaerobic degradation
therefore they do not generally persist in the outdoor
environment.
26. Persistence
Outdoor air concentrations are higher in urban and suburban areas
than in rural and remote areas. Indoor air concentrations are
generally higher than outdoor air concentrations due to the nature
of the sources.
Phthalates can accumulate in some simple, aquatic organisms.
However, most higher organisms (such as fish) are able to
metabolise them and break them down. Therefore, biomagnification up
the food chain does not usually occur. Inside the body, they break
down and are excreted.
27. Exposure
People are commonly exposed to phthalates. Exposure can be through
direct use or indirectly through environmental contamination.
Phthalates can emanate from:
Air: industrial air pollution
Water: sewage sludge and treated water, tap water, industrial
effluent
Environment: agricultural land
Direct contact with consumer products: adhesives, detergents,
flooring, inks, paints and coatings, plastics, rubber, deodorant,
fragrances, hand lotion, insect repellent, shampoo, soap, medical
tubing.
28. Ingestion
Ingestion is believed to be the main source of DEHP and other
phthalates in the general population, with fatty foods such as
milk, butter, and meats a major source. Low molecular weight
phthalates such as DEP and DBP may be dermally absorbed.
Inhalational exposure is also significant with the more volatile
phthalates.
Phthalates are also found in medications, where they are used to
produce enteric coatings. Exposures from phthalate-containing
medications can far exceed population levels from other sources.
This raises concern due to the high level of exposures associated
with taking these medications, especially in vulnerable segments of
the population including pregnant women and children.
29. Exposure in Infants
Children's exposure to phthalates generally is greater than adults.
This is partially due to their mouthing behaviour. A 2008 study
reported the use of infant lotion, infant powder, and infant
shampoo were associated with increased infant urine concentrations,
suggesting dermal exposures may also contribute significantly to
phthalate body burden in this population. Infants are more
vulnerable to the potential adverse effects of phthalates given
their increased dosage per unit body surface area, metabolic
capabilities, and developing endocrine and reproductive
systems.
30. 31. 32. References
http://www.endocrine-disruptors.net/about_endocrine_disruptors.html
http://en.wikipedia.org/wiki/Endocrine_disruptor
http://en.wikipedia.org/wiki/DDT
http://www.whale.to/vaccines/ddt_spraying.html