Transcript DDT - University of California, Irvine
DDT
Other Names
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Anofex, Cesarex, Chlorophenothane, Dedelo, p,p' DDT, Dichlorodiphenyltrichloroethane, Dinocide, Didimac, Digmar, ENT 1506, Genitox, Guesapon, Guesarol, Gexarex, Gyron, Hildit, Ixodex, Kopsol, Neocid, OMS 16, Micro DDT 75, Pentachlorin, Rukseam, R50 and Zerdane
WHAT IS DDT?
• DDT is banned in the United States in 1972 after scientists discovered its harmful effects. It is in EPA Toxicity Class II (moderately toxic).
• DDT is an organochlorine insecticide used to control mosquito. It has been replaced by more environment friendly insecticide. It was widely used during the Second World War to control insect typhus and malaria vectors from harming Allied soldiers, and continued as an agricultural insecticide in 1945. • It is available as aerosols, dustable powders, emulsifiable concentrates, granules and powders. It can be used with many other pesticides but shouldn’t be mixed with alkaline substances.
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Toxicity
DDT ranges from acute to chronic toxicity. It easily absorbs with fat. “In experiments oral ingestions in mammals, LD50s range from 113 to 800 mg/kg in rats; 150-300 mg/kg in mice; 300 mg/kg in guinea pigs; 400 mg/kg in rabbits; 500-750 mg/kg in dog and greater than 1,000 mg/kg in sheep and goats. Toxicity will vary according to formulation. DDT is readily absorbed through the gastrointestinal tract. One-time administration of DDT to rats at doses of 50 mg/kg led to decreased thyroid function and a single dose of 150 mg/kg led to increased blood levels of liver-produced enzymes and changes in the cellular chemistry in the central nervous system of monkeys. Single doses of 50-160 mg/kg produced tremors in rats, and single doses of 160 mg/kg produced hind leg paralysis in guinea pigs. Mice suffered convulsions following a one-time oral dose of 200 mg/kg. Single administrations of low doses to developing 10 day old mice are reported to have caused subtle effects on their neurological development.” – From a study at Cornell University.
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• • • • DDT can not be absorbed through the skin unless it is in a solution. It can be inhaled and absorbed through the lung alveoli in which the harmful effects vary by differences in amount of dosages. If mild it causes nausea, diarrhea, increased liver enzyme activity, irritation (of the eyes, nose or throat), disturbed gait, malaise and excitability.
In high dosage it causes convulsions and tremors.
5.) There are no connection Between maternal blood level and miscarriage or premature rupture of fetal membranes according to the studies 1) In the case of Animals study, they found evidence that DDT cause productive effects.
Reproductive Effects 2.) In mice the amount of 1.67 mg/kg/day Will result in decreased embryo implantation and abnormality in the estrus cycle over a long period of time which is around 28 weeks
4.) Evidence from two epidemiological Studies does not show that Reproductive effects have occurred in human do to the DDT exposure 3.) It was assumed that Several of these observed effects could be the result of disturbance in the endocrine system (hormonal)
Teratogenic Effects
1.)
Evidence proved that DDt causes Teratogenic Effects; base on the rat experience the amount of 26 mg/kg/day DDt will result in impaired learning performance in the maze tests .
2.) There are no Epidemiological evidence that relates to the Teratogenic Effects due to the exposure of DDT 3.) It’s possible that Teratogenic Effects will not occur in human due to DDT exposure levels
Mutagenic Effects
according to research evidence for Mutagenicity and Genotoxicity is opposing.
Only 1 out of 11 mutagenicity attempt in various cell cultures and organisms did DDT show positive result. In human studies, blood cells are Constantly exposed to DDT Illustrate an increase in chromosomal damage “a separate study, significant increases in chromosomal damage were reported in workers who had direct and indirect occupational exposure to DDT.”
DDT EFFECTS
BIRDS AQUATIC SPECIES EARTH WORMS OTHERS BIOLOGICAL FACTORS
AQUATIC AND DDT •
DDT are highly toxic when it comes with water and inflicting great damages on aquatic species including invertebrates (stoneflies, midges, crayfish, sow bugs, salmon, rainbow trout, largemouth bass…ect)
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According to research and studies, early development in species and invertebrates are more vulnerable than adult exposure to DDT.
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In addition to sharpen toxic effects, DDT may biologically accumulates significantly in fish and other aquatic species, leading to long-term exposure. This result possibly because of the uptake from sediment and water into aquatic flora and fauna, and also fish
EVIRONMENTAL EFFECTS • • •
With a half life between 2 to 15 years DDT is known to be highly persistence in the Environment and concealed in most of the soil.
Because of its low solubility in water, DDT will consumes a greater degree by soils and soil fractions with higher proportions of soil organic matter. It may build up in the top soil layer that is when heavy application are annually made for example apples It’s because of high persistency (2-15 years) DDT slowly concentrate through the soil and possibly leach into ground water which will then increases greater exposure.
BREAK DOWN OF CHEMICAL IN WATER SURFACE • • •
DDT reach water surface through different ways but primarily by runoff, atmospheric transport, drift and also direct application. Studies concludes that DDT’s half life in water environment lasted around 56 days in lake and approximately in the estimation of 28 days in rivers.
The main pathway for loss are volatilization, photo degradation, adsorption to water-borne particulates and sedimentation and mostly the aquatic species has already consumes most of the DDT.
PHYSICAL PROPERTIES AND GUIDELINES
Exposure Guidelines: Physical Properties: ADI:0.02 mg/kg/d HA:Not Available RfD:0.0005 mg/kg/day PEL:1 mg/meters cubed (8-hour) Chemical Name: 1,1,1- trichloro-2,2-bis(4 chlorophenyl) ethane CAS:50-29-3 Molecular Weight:354.51 Water solubility:1 mg/L at 20 degrees C Solubility in other solvents: cyclohexanone v.s., dioxane v.s., benzene v.s., xylene v.s., trichloroethylene v.s., dichloromethane v.s., acetone v.s., chloroform v.s., diethyl ether v.s., ethanol s. and methanol s. Melting Point:108.5-109 degrees C Vapor Pressure:0.025 mPa at 25 degrees C Partition Coefficient(octanol/water): 100,000 (
)Adsorption Coefficient:245,000 (
HISTORY •
DDT was manufacture in 1873 , and its insecticidal properties were discovered by the Swiss scientist Paul Hermann Mullar in 1939 who was awarded the 1948 NOBEL PRIZE in Physiology and Medicine for his efforts. DDT is the best known of a number of chlorine-containing pesticides used in the 1940s and 1950s. It was extensively used during WWII among Allied troops and certain civilian populations to control insect typhus and malaria vectors. Entire cities in Italy were dusted to control the typhus carried by lice. DDT was also extensively used as an agricultural insecticide after 1945. In the 1950s, in some uses doses of DDT and other insecticides had to be doubled or tripled as some resistant insect strains developed, and evidence began to grow that the chemical was concentrated in the food chain.
CONTINEUS •
DDT’s purpose was to eradicates malaria from Europe and North America. Until today malaria is thought of as a tropical disease, it even more widespread prior to malaria eradication program carried out in the 1950s. The program was highly successful worldwide reducing mortality rates from 192 per 100,000 to a low of 7 per 100,000. It was less effective in tropical regions due to the continuous life-cycle of the parasite and poor infrastructure. It was not pursued aggressively in sub-Saharan Africa due to perceived difficulties. Among the result that mortality rates there were never reduced to the same dramatic extent and now constitute the bulk of malarial deaths in worldwide especially following the resurgence of the disease as a result of insect resistance to DDT. microbe resistance to drug treatments and the spread of the deadly malarial variant were caused by Plasmodium Falciparum.
CONTROVERSIES
DDT is also known as Dichloro-diphenyl trichloroethane (ClC6H4)2CH(CCl3). It is a colorless crystalline substance which is practically insoluble in water but highly soluble in fats and most organic solvent . It was created as the first of the modern insecticides early in WWII . It was initially used with great effect to kill mosquitoes spreading malaria, typhus and other insects that bome human diseases among both military and civilian populations. Around the early 1960s, Rachel Carson wrote the book “Silence Spring” which then aroused public opinion against DDT with her claim that DDT caused cancer and harmed bird reproduction by thinning egg shells; the resulting outcry eventually led to the pesticide being banned for agricultural use worldwide and was one of the signature events in the birth of the environmental movement .
BANNING THE DDT
The book Silent Spring written by Rachel Carson brought a great deal of controversies and arguments within the Science fields even the Government was involve. The book launched the modern Environmental movement and DDT soon become the primary target of the growing anti chemical and pesticide supporters during the 1960s. The anti DDT movement was rapidly getting stronger and around the world. Until 1970, DDT was banned from Norway, Sweden, and 1984 it was banned in the United Kingdom. In U.S , the EPA's first Administrator, Environmental Defense Fund supporter William Ruckelshaus, defying his science advisors, announced a ban in 1972 on virtually all uses of DDT in the U.S., where it is classified in EPA Toxicity Class II. Despite the U.S. ban on usage, chemical factories in the U.S. continued to manufacture and export DDT to Third World countries for years.
CONTINUE THE BANNING
UNDERTAKER HITS THE
DDT •
The 1970s DDT ban in the United State cause a climax of public mistrust of the science and industrial community. In understanding the public policy landscape that led to the ban, it is important to realize that there were essentially no restrictions in the U.S. on pesticide manufacture and use during the
1940s
and
1950s
. This, coupled with the fact that fewer people in the '60s were as concerned with environmentalism as people are today, led to impure products, little knowledge of any risks on the part of the pesticide users, over application, and ignorance of any long-term environmental damage that might occur.
ANY DDT SUPPORTER?!!!
• Controversy remains in some scientific circles over DDT's actual toxicity, however. Some scientists have protested that the laboratory animal studies done in 1969 which led to the banning of DDT in much of the developed world. This showed that DDT caused an increase in liver cancer was inconsistent with observations in the wild, given that DDT had been used widely during the preceding three decades with no increase in liver cancer in any of the human populations among whom it had been sprayed
SUPPORT ME!!!
THE MOST ELECTRICFYYING maneuver of all time the DDT…If ya smell what The ROCK is COOKIN
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When the World Health Organization investigated the 1969 mouse study, they found that both experimental and control groups had developed a surprising number of tumors. Further investigation revealed that the food fed to both groups were moldy and contained aflatoxin, a carcinogen. When the tests were repeated using uncontaminated foods, neither group developed abnormal numbers of tumors.
CONTINUE
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In many African nations, the health problems resulting from millions of malaria per year are viewed as greater than the potential dangers of DDT. In 2001, after a five-year ban led to more than a ten-fold increase in malaria cases, South Africa permitted its use again. Uganda also began permitting its use in anti-malarial efforts despite a threat that its agricultural products to Europe would be banned as a result. One of the arguments against continuing its ban was that DDT was being used anyway in uncontrolled amounts.
MORE OPPINION •
Dr. Elizabeth Whelan, the president of the American Council on Science and Health claims that 60 million or more lives "have been needlessly lost since the ban on DDT took effect. ... It's a real tragedy that DDT has been so demonized over the years by activist organizations such as Environmental Defense and the regulatory bodies that they have duped."1
TODAY
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However, the ban on DDT did not significantly interfere with its use as an anti-malarial agent; malarial deaths remain depressed in most of the world, except for Africa, where they have been climbing steadily since 1900. The World Health Organization attributes most of the increase in malarial deaths to insect resistance to pesticides for example DDT and malaria pathogen resistance to drug treatments, in addition to generally poor health of much of the African population. However, it continues to fight against a total ban on DDT use (advocated for by the Worldwide life fund amongst other organizations).