DDT production

The chlorobenzene operations in the United States were developed primarily for the manufacture of phenol, aniline, and DDT. However, with the process changes in the production of phenol and aniline, the phase-out of DDT production, and changes in the herbicide and solvent markets, the U.S. production of chlorinated benzenes has shmnk by more than 50% since the total production peaked in 1969. U.S. production of monochlorobenzene peaked in the 1960s and decreased to a low of 101 million kg in 1986 with an 11% and 9% increase, respectively, in 1988 and 1989. 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

Recalling the three million people who had died of typhus after World War I, Geigy also developed DDT products to kill lice. After studying Muller s compound, a Swiss typhus expert confirmed DDT s usefulness in killing the typhus carriers. Next, DDT was tested on pest-ridden Italian refugees in Swiss internment camps and on soldiers in the Swiss Army. 

Paul Hermann Muller. Encyclopaedia Britannica, vol. 6. Chicago Encyclopaedia Britannica Inc., 1979. Source for 1968 DDT production and DDT s half-life in the environment. 

The chlorinated chemicals assessed do not have the same risk profile. For the more volatile chemicals the safety margins between the actual exposure and the level at which no effect on the environment would be expected is quite high. For more persistent chemicals there is a need to look to the environmental compartment where they can be accumulated (mainly in sediments and biota). For some of these chemicals the safety margin is quite low and in worst-case situations serious effects may occur. For the very persistent, bioaccumulative and toxic chemicals (like dioxins, PCBs and DDT), acceptable environmental concentrations are so low and difficult to control that the industry is committed to reducing as far as possible releases to the environment through application of Best Available Techniques (BAT), mainly with respect to dioxins. For other chemicals (PCBs, DDT), production has already been halted for some years. 

Production of chlorobenzene in the United States has declined by nearly 60%, from the peak production volume of 274,000 kkg in 1960 to 112,000 kkg in 1987. This decline is attributed primarily to the replacement of chlorobenzene by cumene in phenol production and the cessation of DDT production in the United States. In addition, pesticide production using chlorobenzene as an intermediate has declined and no major new uses have been found for chlorobenzene in recent years. Therefore, the decline in chlorobenzene production is expected to continue (EPA 1980c, 1985 Hughes etal. 1983 USITC 1988). 

The current primary uses of chlorobenzene are as a solvent for pesticide formulations, diisocyanate manufacture, degreasing automobile parts, and for the production of nitrochlorobenzene. Solvent uses accounted for about 37% of chlorobenzene consumption in the United States in 1981, nitrochlorobenzene production for 33%, and diphenyl oxide and phenylphenol production for 16% of consumption. Chlorobenzene is also used in silicone resin production and as an intermediate in the synthesis of other halogenated organics. The past major use of chlorobenzene was as an intermediate in phenol and DDT production (Hughes et al. 1983). 

There is a large volume of stockpiled or waste DDT in some DDT-producing sites, including those where DDT production has ceased for many years. Seven DDT producers have never cleaned their operating sites where DDT wastes still remain. These have become potential polluting sources. 

Uses The technical p,p -DDT is a waxy solid, but in its pure form, it appears as colorless crystals. It is a mixture of three isomers p,p -DDT isomer (approximately 85%), ,//-DDT, and 0,0 -DDT (in smaller levels). DDT is soluble in solvents such as cyclohexanone, dioxane, benzene, xylene, trichloroethylene, dichloromethane, acetone, chloroform, and diethyl ether. It also is soluble in ethanol and methanol. The USEPA has grouped DDT under restricted use pesticide (RUP). Two similar chemicals that sometimes contaminate DDT products are DDE (l,l-dichloro-2,2-bis(chlorophenyl) ethylene) and DDD (1,1-dichloro-2,2-bis(p-chlorophenyl) ethane). DDD also was used to kill pests, but its use has been banned. One form of DDD has been used medically to treat cancer of the adrenal gland, but DDE has no commercial use.14,35... 

In order that we may keep our perspective, let us consider the all-time world production of DDT in another way. As quoted by Gunther and Jeppson (9), the total arable land area in about 90 counties in the world is 2,287,000,000 acres. The total land area is probably about 10 times this amount. DDT production in the United States since 1952 has been about 1,801,000,000 pounds. Estimating U.S. production prior to 1952 at 500,000,000 pounds and production in the rest of the world at 1,150,000,000 pounds to date, we arrive at a total of about 3,500,000,000... 

Sladen et at (9) reported finding DDT products, in the range of 13-152 in the tissues of penguins and a seal captured in the Antarctic. They speculated on several modes of transport of DDT to this remote part of the world. Transmission via the food chain and by animal migration was considered to be the principal mode of contamination. Transport by contaminated air and water were considered unlikely. 

Briefly, this study focuses on the vertical distribution of DDT and its metabolites in undisturbed sediment layers located in the same sampling area (location TKS, Figure 1). The correlation of the detected concentrations with the stratigraphical sediment profile reflects not only a geochronolgical increase or decrease of these compounds, but also the possibility to reflect the ban as well as the resulting restriction and termination of the DDT-production at this industrial area. 

The decreasing concentrations from the 30 cm layer towards the top of the sediment core characterise a decline in emission. This can be attributed to the reduction of the industrial DDT-production since 1975. Following, the highest production rates can be attributed to a time period corresponding to the lowest sediment layers between 24 and 30 cm. 

Chlorobenzene, also called monochlorobenzene, is a monocyclic aromatic compound. It is a colorless liquid with an aromatic almond-like odor and is manufactured for use as a solvent, is used in the production of other chemicals (pesticides), and in making certain other chemicals, rubber, dyes and grease solvents. It is used as a feedstock to produce ortho- and para- nitrochlorobenzenes and aniline as a solvent for paints and as a heat transfer medium. In the past, chlorobenzene was used as an intermediate in phenol and DDT production. Chlorobenzene enters the environment from industrial and municipal discharges. Another potential source is the formation and emission of chlorobenzene as a product of incomplete combustion in waste incinerators. 

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