After receiving his Ph.D. in chemistry from 65438 to 0925, Miller was employed as a pharmacist by Chigi Company in Switzerland. 1935 because of the need of agricultural production, the company asked him to screen a powerful and low-toxic pesticide. At that time, the relevant literature was overwhelming, and the number of patented pesticides was amazing, but in fact, almost no pesticides actually entered the market effectively. He is determined to solve this problem in the face of frequent insect disasters in rural areas, including his hometown. How to solve it? One day, he suddenly remembered a famous saying of China: Fight poison with poison. Inspired by this, he tried to screen new pesticides according to this idea.
Miller aims at an ideal pesticide that meets the following seven indicators: (1) highly toxic to insects; (2) rapid onset of toxicity; (3) little or no toxicity to warm-blooded animals and plants; (4) no irritation and odor; (5) The insecticidal spectrum should be as wide as possible; (6) stable chemical properties, that is, long action time; (7) low price.
In a laboratory with relatively poor equipment, after nearly four years of arduous screening tests on hundreds of drugs, he produced DDT as an insecticide in September of 1939, which had amazing contact killing effect on houseflies. At that time, he thought that except for the second item, the other six indicators could be achieved. Then he prepared various derivatives of DDT. After many detailed experiments, the contact killing effect of DDT on pests was recognized by the chemical industry, and it was put into the market on 1942 after repeated improvement of manufacturing technology.
1943 The United States Department of Agriculture tried to kill potato beetles with DDT, which proved that DDT had a good insecticidal effect. 1944 1 In the Battle of Naples, Italy, lice-borne typhus was prevalent, and 60 new cases appeared every day. The officers and men were desperate. Due to the use of DDT, lice were eliminated for 1.3 million people in three weeks, and the epidemic of typhus was put down. Three months later, a similar disease appeared in Japan, and it took DDT to turn the corner.
As a pesticide, DDT is widely used in agricultural production in the future, and it has become an effective means for fields and farmers to quickly defeat pests. At the same time, in medical and health, DDT is a good medicine to eradicate infectious diseases. Therefore, DDT has shown great effectiveness in agricultural production practice and medical and health practice. Therefore, people regard DDT as "the savior of mankind".
At that time, people thought DDT was a harmless pesticide. Its harmlessness is based on a large number of facts, or it has been tested by practice: during the Second World War, DDT powder was sprinkled on thousands of soldiers, refugees and prisoners to kill lice, which was very effective, but the human body was not harmed. Since so many people have dealt with DDT powder and have not been hurt, it shows that this drug is beneficial and harmless to human body. During the period of 1948, Miller won the Nobel Prize in Physiology and Medicine for discovering that DDT and its chemical derivatives were highly toxic to pests.
In fact, DDT is harmful to biology and human body, but this kind of harm was gradually discovered and confirmed in a series of practices in the next ten years.
Since the 1950s, scientists have made the following understandings by observing various practical phenomena and conducting various scientific experiments:
(a) powder DDT is not easily absorbed by human skin, so it does not show its toxicity, but it must be toxic after being dissolved in oil. If liquid DDT is swallowed and enters the human body through the digestive tract, it will be stored in a large number of fat organs.
(2) DDT spreads from one organism to another through all links in the food chain. For example, DDT powder is scattered in alfalfa fields, and then the alfalfa here is used as feed for chickens, and the eggs laid by chickens contain DDT. For another example, if cows are fed with DDT hay containing 7-8 parts per million, the DDT content in milk will reach about 3 parts per million, and in the cream made from this milk, the DDT content will increase to more than 60 parts per million due to concentration.
(DDT seeps into water and enters aquatic organisms. 1960 the investigation report of the us fisheries and wildlife administration said that DDT was sprayed on a large area in some places to control the maggots on the Yunbin trees. Results DDT was found in fish in a small river bend about 15 km away from the spraying area. According to the research, the rainwater containing DDT on the ground continuously seeps down through the pores and cracks of soil and rock, which pollutes the underground water body. Due to the flow of groundwater, DDT is brought into streams and rivers, and enters organisms in rivers.
(d) It is increasingly found that DDT kills a large number of beneficial insects and pests. 1958 an American housewife wrote to a bird expert: in her village, she has been spraying DDT on elm trees for several years. At first, there were many kinds of birds here, but later these birds stopped coming. Why don't all the birds come? Dr. R. Barker of the Illinois Institute of Natural History in the United States stated in the book published in 1958 that DDT not only killed the beetle to be eliminated, but also killed many beneficial insects. Poison forms a strong mucous membrane on leaves and bark. In autumn, elm leaves fall to the ground, which happens to be earthworm's favorite food, so DDT enters earthworm's body and accumulates deeply in earthworm's digestive tract, blood vessels, nerves and body wall. Some earthworms can't resist this toxin and die, while the surviving earthworms become food for birds. Earthworms can kill a bird.
People gradually realize that the harm of DDT to biology and human body should not be underestimated and should not be used again.
People have also discovered the problem of "insect resistance" through practice. It is found all over the world that after using DDT for several years, many insects, such as flies, mosquitoes, bedbugs, fleas and lice, have developed drug resistance. DDT is not as effective as before in killing pests.
Since 1960s, some countries and regions have stopped producing and using DDT. By 1970s, DDT had been banned by all countries in the world. Scientists have discovered and produced some new low-toxic chemical pesticides, which has opened up a new direction for the manufacture of biological pesticides that are harmless to people.
The process of DDT from hero or savior to culprit, from prosperity to extinction is precisely the process of people's understanding of DDT gradually deepening and gradually comprehensive in more updated practice.
Someone asked: Is it "a mistake" to award the Nobel Prize to Miller in 1948? The answers are not consistent. How to treat DDT in the history of human civilization? I think it is an indisputable historical fact that DDT has greatly increased agricultural output, made some infectious diseases no longer popular and saved many desperate patients. The inventor of DDT did make a contribution, and it was understandable to win the Nobel Prize at that time. As for whether the Nobel Prize must have been awarded as early as 1948, it seems that we can think more about it now.
As "wise after the event", instead of condemning DDT for winning the Nobel Prize as "a mistake", we should guide people to seriously sum up the valuable experience of human cognition from the history of DDT's rise and fall: human cognition and practice test are inseparable. Practice is the only criterion for testing truth, but practice itself is historical and relative. The one-sidedness of cognition often stems from the limitations of practice. Truth cannot be obtained from a cognitive process, and testing cannot be completed in a practical process. Knowledge must be constantly developed in new practice.