Science: DDT

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Censorship was lifted last week from one of the great scientific discoveries of World War II. It is an insecticide called DDT. DDT stopped a typhus epidemic in Naples. It promises to wipe out the mosquito and malaria, to liquidate the household fly, cockroach and bedbug, to control some of the most damaging insects that prey on the world's crops. Lieut. Colonel A. L. Ahnfeldt, of the U.S. Surgeon General's office, exclaimed last week: "DDT will be to preventive medicine what Lister's discovery of antiseptics was to surgery."

The use of DDT as a delousing agent against typhus has been an open secret for several months. But last week for the first time its manufacturers and Army, Agriculture and WPB officials joined in announcing some of its other amazing properties:

¶ Sprayed on a wall, it kills any fly that touches the wall for as long as three months afterward.

¶ A bed sprayed with DDT remains deadly to bedbugs for 300 days.

¶ Clothing dusted with it is safe from lice for a month, even after eight launderings.

¶ A few ounces dropped in a swamp kills all mosquito larvae.

¶ It is deadly to such common household pests as moths, roaches, termites, dogs' fleas.

¶ As a crop protector, it is deadlier and longer lasting than other insecticides, has been found effective against potato beetles, cabbage worms, apple codling moths, Japanese beetles, aphids, fruit worms, even corn borers — against which previous insecticides have proved to be failures.

So great are DDT's potentialities that no fewer than seven U.S. laboratories and hundreds of biochemists are concentrated on it. Production has multiplied 350-fold in the last year; four manufacturers are now turning out about 350,000 pounds a month—all for the Army.

Beetle Blaster. Last week the developers of DDT, Geigy Co., Inc., an old dye firm with branches in Switzerland and New York, told reporters in Manhattan how the chemical was discovered. Like penicillin, DDT was known long before its usefulness was appreciated. A complicated chemical (full name: dichloro-diphenyl-trichloroethane), whose chief ingredients are chlorine, alcohol and sulfuric acid, DDT was first synthesized in 1874 by a German student named Othmar Zeidler. He had no idea of its possibilities as an insecticide, dismissed his discovery in six lines in a German chemical journal.

But on the eve of World War II a Geigy chemist, Paul Muller, rediscovered the formula and found that it killed bugs. Its first test came during a plague of potato beetles in Switzerland in 1939. DDT stopped the beetles dead. Concentrated DDT is toxic to men and animals when swallowed, but in the weak dilutions used for sprays and dusts, it has been found harmless to the skin.

By 1942, the U.S. Department of Agriculture had begun to experiment with DDT, got such sensational results that the Surgeon General's office and Dr. Vannevar Bush's OSRD launched a full-scale investigation, soon uncovered DDT's immense military possibilities.

The crucial problem was finding a feasible process for producing DDT in the large quantities needed. It was solved last year by a Swiss-born chemist, Dr. Oskar Frey, of the Cincinnati Chemical Works. Cincinnati Chemical still produces 60% of the DDT supply.