3.  DDT is a synthetic chemical compound once used widely in US and throughout the world as pesticide- a chemical substance used to kill weeds, insects, rodents or other pests. It is remarkably known for its dual nature: although remarkably effective in destroying certain living things that are harmful to plants and animals, it can also be extremely dangerous to humans and the environment. The compound was first produced in the laboratory in 1873. prior to the introduction of DDT, the disease malaria was completely eliminated from the island in 1963. it was effective against malarial mosquitoes because of its persistence – its resistance to breakdown in the environment. One or two sprays on the walls of homes keeps them away from mosquitoes for a year.

4.  Aim- To study the ecological, chronic, reproductive, teratogenic, mutagenic, carcinogenic and environmental effect of the insecticide(DDT). REGULATORY STATUS- DDT is no longer registered for use in the United States, although it is still used in other tropical countries.  It is in EPA toxicity class II, moderately toxic. It was banned in the United States in 1972.  Physical Properties- the physical appearance of technical product p,p’-DDT is a waxy solid, although in its pure form it consists of colorless crystals.  CAS: 50-29-3  Molecular Weight: 354.51  Water Solubility: 1mg/l @ 20 degrees C  Solubility in other solvents: it is soluble in cyclohexane, dioxane, benzene, xylene, trichloroethylene, dichloromethane, acetone, chloroform, diethyl ether, ethanol and methanol.  Melting point- 108.5-109 degree C  Vapor pressure: 0.0025 mpa @ 25 degrees C  Coefficient(octanol/water): 100,000  Adsorption Coefficient: 245,000

5.  ACUTE TOXICITY: ddt is moderately to slightly toxic to studied mammalian species via the oral route. It is readily absorbed through the gastrointestinal tract, with increased absorption in the presence of fats. One time, administration of ddt to rats at doses of 50mg/kg led to decrease thyroid function and a single dose of 150mg/kg led to increased blood levels of liver- produced enzymes and changes in the cellular chemistry in the central nervous system of monkeys. Acute effects likely in humans due to low to moderate exposure may include nausea, diarrhea, increased liver enzyme activity, irritation of the eyes, nose or throat, disturbed gait, malaise and excitability; at higher doses, tremors and convulsions are possible.

6. DDT has caused chronic effects on the nervous systems, liver, kidneys and immune systems in experimental animals. It causes tremors in rat and mice at higher doses. It also causes changes in cellular chemistry of the central nervous system of monkeys at a dosage of 10mg/kg over 100 days. These adverse chronic effects has not been observed on human being.

7. there is evidence that DDT causes reproductive effects in test animals but none in human beings. In a study of rats, oral doses of 7.5mg/kg /day for 36 weeks resulted in sterility.In mice, doses of 1.67 mg/kg/day resulted in decreased embryo implantation and irregularities in the estrus cycle over 28 weeks.

8.  DDT causes teratogenic effects in some animals. In mice, for instance, maternal doses of 26mg/kg/day DDT from gestation through lactation resulted in impaired learning performance in maze tests. It also resulted into abnormal tail development in rat study.

9.  The evidence for mutagenicity and genoticity is contradictory. In humans, blood cell cultures of men occupationally exposed to DDT showed an increase in chromosomal damage. It is therefore clear that DDT is capable of causing genotoxic effects in humans, but does not appear to be strongly mutagenic.

10. The evidence regarding the carcinogenicity of DDT is equivocal. It has been showed to cause increased tumor production(mainly in the liver and lung) of test animals such as rats, mice and hamsters. In other studies, however, no carcinogenic activity was observed in rats, mice and hamsters at doses less than 25mg/kg/day.

11.  DDT REPLACEMENT : because of the aforementioned adverse effects caused by DDT, it becomes necessary to look for a chemical compound that has lesser destruction effects on the environment. Methoxychlor or methoprene can replace DDT.  METHOXYCHLOR : it was used an insecticide effective against a wide range of pests including biting flies, houseflies, mosquitoe larvae, cocroaches and chiggers.it was also used as an ecto parasiticide.the most probable route of exposure to methoxychlor would be from inhalation or dermal contactby workers involved in the manufacture and handling of it. Tests have been developed to detect methoxychlor in blood, fat, semen and breast milk. However, the use of methoxychlor was banned in 2000, because of its adverse effects.