DDT Chemistry Project- Paul S.

dichlorodiphenyltrichloroethane

Brief Introduction

DDT (dichloro-diphenyl-trichloro-ethane) is an insecticide that was commonly used from the 1940s to the 1970s

At one point, around one billion kilograms of DDT were released into the environment

DDT was banned in Canada and in the US in 1972

DDT has an interesting chemical compound that has many advantages and disadvantages

Chemical Structure

Chemical Information

- The chemical formula for DDT is C14H9Cl5

- DDT is made up of 14 carbon atoms, 9 hydrogen atoms and 5 chlorine atoms

- DDT is a molecular compound because it is made up of only non-metals

- The shape of the compound is two hexagonal rings with a tetrahedral separating them and another tetrahedral extending upwards from the first tetrahedral

- It is a non polar molecule because both sides are symmetrical which means that all sides have the same charge

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Common Uses

- DDT was usually used as a pesticide to kill unwanted insects that destroyed farmers crops

- DDT was extremely effective in doing this

- In fact, crop production dramatically increased in the 1950s and 1960s, when DDT was most commonly used

- DDT was also used indoors for pest control

- DDT has helped control malaria, typhus and many other insect transmitted diseases

- Cases of malaria have decreased from 400,000 in 1946 to virtually none in 1950

- Even to this day, DDT is still used in parts of Africa and other third world countries for this reason

Physical and Chemical Properties

Physical:


White, Odourless, Powder


Melting Point - 109 degrees Celsius - low melting point because the molecule is non polar, therefore it has dispersion forces which is the weakest intermolecular force


Boiling Point - 260 degrees Celsius - it has a very high boiling point because of it's molecular size


Very low solubility in water - low solubility because DDT is a non polar molecule and H2O is a polar molecule so the two don't mix




Chemical Properties:


DDT's chemical structure is very stable which means it is very hard to break down the molecule.


DDT breaks down faster when in contact with a strong alkaline solution


DDT is neither a acid or a base. It measures as a 7 on the ph scale which means its neutral.


DDT is combustable because it has the elements Carbon, Hydrogen, and Oxygen in its chemical structure

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Benefits/Cost to Human Health

Benefits:


DDT was first popularly used during WW2 in 1943, when the British and American military forces used it to prevent the spread of insect transmitted diseases, such as malaria, body lice and the bubonic plague


The Russian military forces successfully used DDT to stop a typhus epidemic


Still used in many third world countries to stop the spread of malaria.


At one point in time DDT was nicknamed the "Miracle Insecticide"



Costs:


DDT has a huge negative impact on the environment due to bioaccumulation and biomagnification


DDT's chemical properties, such as its toxicity, its high stability, its inability to dissolve in water and its ability to dissolve in fat has made it an even more dangerous chemical


In cases with small organisms such as birds, permanent paralysis or convulsion (uncontrollable spasms in the muscles) may occur when heavily consumed.


There are some studies that have suggested that DDT can cause breast cancer in women


Some people exposed to DDT have also reported cases of vomiting, nausea, headache, fatigue, nervous tension, dizziness and confusion


DDT has caused birds to lay thin layered eggshells which resulted into early birth and not enough development


Studies have also shown that DDT can affect the reproductive system in many mammals, including dogs, rats and mice


More studies have shown that exposure to DDT can also cause liver cancer in certain mammals


When it rains, DDT that is trapped in the soil is moved through underground waterways into big rivers and lakes where it pollutes the water, causing the fish that we eat to be laced with the toxic chemical


Even though DDT has been banned in North America for a number of decades, traces of DDT are still found in some soil because it is so hard to break down.

Safe and Alternate Uses

Organic Farming:


- Uses natural renewable resources


- Conserves water


- Doesn't use pesticides and commercial fertilizers


- Doesn't endanger workers


- Foods are produced without hormones, antibiotics, herbicides, insecticides, chemical - fertilizers, genetic modification, or germ-killing radiation


- Higher levels of beneficial minerals


- Uses naturally occurring disease organisms, parasites, or predators to control pests


- This method is especially effective when exotic species become the pests because their natural predators can be taken from their native land and applied to kill the pest


- Includes insects and bacteria that work to kill the pests

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Biomagnification

-Biomagnification is when the concentration of a substance increases as the the food chain goes up


-This happens because energy is lost (from respiration) as you go up the food chain,

but DDT is not


-Biomagnification harms animals (especially those in the top of the food chain)


For example: if there was 0.04 ppm in zooplankton, there would be 25 ppm in fish-eating birds since they eat large fish, large fish eat small fish, and small fish eat zooplankton, so the DDT builds up

Reference List

DDT(dichlorodiphenyltrichloroethane). http://pmep.cce.cornell.edu/profiles/extoxnet/carbaryl-dicrotophos/ddt-ext.html (July, 8, 2014)


DDT: An Introduction. http://people.chem.duke.edu/~jds/cruise_chem/pest/pest1.html (July, 7, 2014)


DDT - Dichloro-diphenyl-trichloroethane. http://www.science.gc.ca/default.asp?Lang=En&n=730D78B4-1 (July, 8, 2014)


Persistent Bioaccumulative and Toxic (PBT) Chemical Program. http://www.epa.gov/pbt/pubs/ddt.htm (July, 7, 2014)


Mader, Sylvia, Bioaccumulation and Biomagnification. http://www.marietta.edu/~biol/102/2bioma95.html (July, 7. 2014)