Othmar Zeidler is a chemist through whose efforts this substance was synthesized in 1873. However, it was not used for a long time and only in 1939, thanks to the efforts of P. Müller, a Swiss chemist, the insecticidal properties inherent in dichlorodiphenyltrichloroethane were revealed. Already at the beginning of 1942, DDT went on sale, quickly gaining popularity around the world.
With its help, it was possible to effectively resist typhoid and malaria, diseases that at that time had the greatest degree of danger to humanity. Spraying alone was enough to ensure reliable protection territory over the next few months.
Müller's efforts were appreciated, and already in 1948 he received the Nobel Prize in Medicine. However, the substance DDT also had a number of negative characteristics, which led to significant environmental pollution in many countries. As a result, already in the early 70s of the last century, serious restrictions on its production and use came into force, which are still relevant today.
Among the main merits attributed to dichlorodiphenyltrichloroethane, one cannot fail to note the following:
- It was thanks to DDT that a typhus outbreak in Naples in 1944 was localized. This was the first time in history that a winter epidemic was stopped;
- thanks to the use of DDT, deaths from malaria that struck India in 1965 were avoided;
- in the same India for 50-60 years. Dum-Dum fever was rampant, but thanks to the use of the drug, many problems were avoided.
Fighting epidemics with DDT spraying
Basic properties of DDT and its analogues
DDT – chemical drug, included in the category of substances based on organochlorine-type compounds. It has a crystalline structure, its color can be different - gray, white or slightly brownish. It does not interact with water, although under the influence of most organic solvents, including ketones, aromatic hydrocarbons and others, it demonstrates excellent solubility.
In the natural environment, dichlorodiphenyltrichloroethane has a long period of decomposition with a negative impact on water resources, plants and the soil itself.
Its transmission occurs along the food chain, the toxic chemical has a tendency to mutate, and when it penetrates inside a living creature, it affects the tissues and nervous system, negatively affecting the ability to reproduce.
Over time, the pesticide accumulates in the body - it is impossible to remove it through cleansing systems.
As for how DDT is deciphered, there is a combination of three components at once - dichloro-diphenyl-trichloroethane, while the content of 4,4'-isomers reaches 75%.
Among the main analogues of this insecticide, the following are particularly distinguished:
- Aldrin is a substance with fairly high toxic levels, prone to accumulation in the body and non-degradable. It has an increased danger to humans, which led to its ban in a number of countries.
- Dieldrin is a chemical based on aldrin, but in a lower concentration. It is less dangerous for living beings, therefore it is very effectively used in agriculture.
Aspects of use and precautions
When using the drug, you should adhere to certain rules, not forgetting about your own safety. It is important to remember that dichlorodiphenyltrichloroethane is extremely dangerous and toxic.
Relevance of pesticide use
The pesticide DDT is especially effective in the following situations:
The manufacturer recommends storing dichlorodiphenyltrichloroethane in a dry and dark place. room temperature. It is important to exclude contact of DDT with products; children’s access to the chemical is also strictly prohibited. Before use, make sure the expiration date is up to date.
Rules for treating open areas with the drug
When treating exposed areas, the following factors should be considered:
- work is carried out in protective clothing;
- An eye mask and a hat are required;
- upon completion of treatment, shake off DDT from clothes, take a shower and change into a clean set;
- optimal temperature regime: +20-22°С, the weather should be calm;
- There should be no pets nearby during processing.
Work with reliable protection
Using the substance at home
Processing is carried out in the following order:
- All unnecessary items are removed from the premises - furniture, food, etc. It is important to take care of personal protection - work is carried out with gloves and a respirator.
- It is better to treat surfaces with a brush. First, apply the pesticide to downsides carpets, thresholds and cladding panels, after which they move on to furniture and ventilation. It is important not to forget about upholstered furniture and all kinds of joints and gaps.
- After treatment, wait approximately 3-4 hours - it is not recommended to stay indoors during this period. After applying dichlorodiphenyltrichloroethane, wash your hands thoroughly and change into clean clothes.
- Upon return, ventilate the room. Smooth surfaces are cleaned using a soda-soap solution. Work is also performed with gloves. Upholstered furniture clean with a vacuum cleaner. From hard to reach places Dichlorodiphenyltrichloroethane does not need to be removed - this way it will continue its protective effect in the future.
Main advantages of dust
DDT for home use from pests
DDT has the following advantages:
- wide spectrum of action - from domestic insects to agricultural pests;
- high degree of processing productivity;
- ease of use - the dust does not require mixing or dissolving, but is immediately ready for use;
- small volumes for treating areas - 50 g is enough to apply per 10 m2;
- acceptable price policy– dichlorodiphenyltrichloroethane has an affordable price, which has a positive effect on its demand and popularity.
Effective pest control
First aid for drug poisoning
For humans, the lethal dose of dichlorodiphenyltrichloroethane is 5-10 g, although very serious consequences are possible with a lesion of 1-1.5 g. Particularly dangerous are oil solutions, from which the pesticide is absorbed at maximum speed.
Dust poisoning causes a feeling of nausea, general weakness of the body, heart problems, pain in the limbs, elevated temperature, as well as a number of other symptoms. Possible problems with the liver and kidneys. In such a case, delay is unacceptable; you should seek qualified medical help as quickly as possible.
Before the medical team arrives, extensive gastric lavage should be performed. For this purpose, a suspension is used activated carbon or a solution based on sodium bicarbonate at a 2% concentration. After this, you should take a saline laxative. The use of castor oil is strictly contraindicated.
Effects of various pesticides on humans
The answer to the question of what dust is and how the drug affects people has been received. Its use, despite all its effectiveness, is fraught with many dangers, therefore, in the absence of proper knowledge and experience, you should abandon dubious experiments and entrust the work to professionals. This will make it possible to save not only time and money, but also health.
Topic: pesticides
Organochlorine compounds
FORGANOSPHORUS COMPOUNDS
In agricultural production great importance attached to organochlorine compounds (OCCs). They have a wide range of pesticide action and are active against harmful insects, mites, and pathogenic fungi. Many COCs are very persistent, highly toxic, and have pronounced cumulative properties.
According to the degree of toxicity among organochlorine compounds there are:
potent toxic substances (chlorine mixture, gamma isomer of hexachlorane),
highly toxic (dichloroethane, hexachlorobutadiene, polychlorocamphene, thiodane),
moderately toxic (DDT, DDD, polychloropipene, polychlorobutane) and
low-toxic (ether sulfonate, tedione, milbeks, phthalan, dilor, etc.) pesticides.
All of them can enter the body of farm animals through
respiratory tract, digestive tract, intact skin.
Most organochlorine compounds are crystalline or amorphous substances, insoluble in water, highly soluble in fats and lipids. Possessing cumulative properties, they accumulate in adipose tissue, the central nervous system and other organs, and are capable of being excreted in milk.
According to their chemical structure, organochlorine compounds are divided into:
chlorinated derivatives of aliphatic hydrocarbons (Hexachlorobutadiene, Nemagon, dichloroethane),
acyclic hydrocarbons (hexachlorane, lindane),
3. aromatic hydrocarbons (hexachlorobenzene, kel-tan, tednon),
polychloroterpenes (polychlorocamphene, polychloropipene),
polychlorocyclodienes (heptachlor, dilor, aldrin).
An important negative indicator of pesticides of this group is their ability to linger in environmental objects for a long time.
COS is considered to be a very persistent and persistent drug; Their half-life lasts for most organochlorine compounds for more than two years.
That is why out of 1.5 million tons of DDT used in the world during the period from 1940 to 1970. only a third has broken down into harmless substances; the rest of DDT with its active metabolites continues to migrate through the food chains of the ecological systems of the biosphere. DDT and its metabolites (DDD, DDE) are still found in toxic concentrations in dolphins, penguins and other marine animals.
Organochlorine compounds are highly soluble in fats (lipids). Once COCs enter the body, they accumulate in subcutaneous and internal fat,
liver, endocrine glands (adrenal glands), brain and spinal cord.
COS have a more pronounced gonadotoxic effect - the metabolism of sex hormones changes, and male infertility develops. Treatment of, for example, reservoirs against mosquito larvae leads to the accumulation of COCs in zooplankton, which then pass through food chains into the bodies of fish, waterfowl, etc.
COCs are detected in meat for up to 6 months, and in kidneys for up to 9 months.
COS are excreted from the body through the intestines, kidneys, and in lactating animals with milk.
It has been established that if roughage contains 7-8 mg/kg of DDT, then milk will contain 3, and butter 70 mg/kg of product.
Chlorine derivatives of aliphatic hydrocarbons
Dichloroethane (DCE, ethylene dichloride) - colorless, highly mobile liquid with the odor of chloroform. Insoluble in water, highly soluble in organic solvents, very volatile. In the presence of water, it hydrolyzes, releasing hydrogen chloride. Highly toxic. For fumigation of warehouse premises, 300-450 g/m3 are used. The maximum permissible concentration (MAC) in water is 2 mg/l, in grain it is allowed up to 7 mg/kg. Severely irritates skin and mucous membranes. The resorptive effect on the animal body is characterized by pronounced inhibition of the central nervous system by type of drug. The pathological process is complicated by nasal and gastric bleeding, conjunctival and intrahepatic hemorrhages, pulmonary edema, and hemolysis of red blood cells. The main metabolite, chloroethanol, is especially toxic.
Nemagon (fumazone) - heavy yellow liquid with a strong odor. Poorly soluble in water, well soluble in organic solvents and oils. Soil fumigant. The consumption rate of the technical preparation in protected ground is 300 kg/ha, granulated up to 1000 kg/ha. Moderately toxic for animals; chickens are very sensitive (LD50 - 60 mg/kg). The drug has supercumulative properties and is highly irritating to mucous membranes and skin.
Heceachlorobutadiene (HCBD)- colorless oily liquid. Poorly soluble in water, well soluble in fats and organic solvents. Used as a herbicide and insecticide. The drug is highly toxic. It has pronounced cumulative properties. Irritates mucous membranes and skin. Embryotoxic, volatile.
Until recently and the beginning of the era of synthetic peritroids, one of the most effective groups of insecticidal drugs was represented by chlorine-containing pesticides (CPPs). These compounds were produced in huge quantities and used over vast areas. A more detailed study of the chemical and biological properties of these compounds led over time to more skepticism towards them and eventually to their complete ban. Over the 40-year period, starting in 1947, when CCP production plants were actively operating, more than 3.6 million tons were produced.
Among OCPs, the most widely used and most fully studied Dichlorodiphenyltrichloroethane (DDT). It was one of the first powerful insecticides, whose widespread use was associated with the fight against malaria and typhus vectors in many countries.
DDT was first synthesized and described in 1873 by the Austrian chemist Othmar Zeidler. Substance for a long time did not find use until Swiss chemist Paul Müller identified and demonstrated its insecticidal properties in 1939. In 1942, Müller, Lauger and Martin proposed the use of DDT as an effective insecticide and patented it.
In 1942, the drug went on sale and began its march across the planet. It was presented as an ideal tool for controlling the vectors of typhus and malaria, diseases that were the biggest medical problems during the Second World War. The toxicity of DDT to humans turned out to be so low that it was supposed to be sprayed on the body to kill body lice and prevent typhus. At one time in the USSR, the so-called “dust soap” containing DDT was produced to combat headaches and pubic lice. It should be noted, in fairness, that the effectiveness of this simple remedy was quite high. A single application was enough.
Relatively low price DDT (importantly) made it possible to use it during World War II to spray entire Pacific islands before the landing of US military forces to destroy malarial mosquitoes there and protect the landing forces from infection. The high stability of the drug, even with a single spray, ensured its effective action for several months. In 1948, Müller was awarded the Nobel Prize in Physiology or Medicine.
Its use has made it possible to sharply reduce mortality from diseases carried by insects. Millions of lives were saved from these diseases using DDT.
Such high efficiency The drug led to the fact that DDT was very widely used as an insecticide in many countries, including in domestic conditions. However, it later became clear that it was precisely the wide spectrum of action and extremely high metabolic and environmental stability that led to the fact that all countries have now abandoned the use of DDT.
Due to the wide spectrum of action, beneficial insects were also destroyed along with harmful ones. And its high stability in the environment led to the fact that DDT accumulated in food chains and had a detrimental effect on their end links.
Further research showed that DDT has an effect on almost all living organisms. Due to high lipophilicity(Log Pow = 6.49 - 6.91) DDT accumulates in the fatty tissues of vertebrates and exhibits its toxic properties with prolonged exposure.
It turned out that DDT is a promoter of carcinogenesis, a mutagen, embryotoxin, neurotoxin, immunotoxin, changes the hormonal system, negatively affecting reproductive function, causes anemia, liver disease, etc.
DDT also has a strong effect on birds, especially predatory and insectivorous birds, leading to thinning of egg shells and thereby preventing the normal hatching of chicks. DDT also reduces reproduction in fish, snakes and carnivorous mammals. The fact is that the bioaccumulation of DDT leads to its biomagnification with a coefficient of about 10 at each link in the food chain. It was found that the concentration of DDT in the fat of birds of prey feeding on fish is approximately 1000 times higher than in herbivorous birds, and 200 - 300 thousand times higher than its concentration in water bodies.
Picture 1. Main metabolites of DDT.
DDT, although slowly, still undergoes metabolic and chemical transformations in the body of vertebrates and in the environment. But its main metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenylethylene (DDE) are no less stable and toxic than the parent substance, and even surpass it in some biological effects. The role of DDT metabolites is often underestimated, although DDE is just as toxic and even more stable than DDT. Thus, in a large study conducted in the USA, it was found that of all six cancers studied by the authors, only mortality from liver cancer directly depends on the concentration of not only DDT, but also its main metabolite DDE in body tissues.
Further studies showed that everything said above about DDT is largely inherent in other representatives of OCPs, such as lindane, mirex, dieldrin, aldrin, HCH, etc.
It is known that DDT, like other POPs, accumulates in human adipose tissue with age. Moreover, it has been established that the main sources of all POPs (up to 95%), including DDT and its metabolites and TCDD for humans are livestock products - meat, eggs and dairy products. It was also noted that DDT and its metabolites account for more than 30% of all pollutants. Beef and dairy products are especially heavily contaminated.
Figure 2. Accumulation of DDT and DDE in human adipose tissue.
When examining the drawing, a question naturally arises. Where does a 5 year old child get such amounts of DDT? Only 3 times less than that of a 90-year-old grandfather. The answer is very simple. With mother's milk.
We recently assessed the levels of selected organochlorines and pesticides in the placenta and breast milk Danish and Finnish women. Among them, the main pollutants were: p,p"-DDE, beta-hexachlorocyclohexane (HCCH), hexachlorobenzene (HCB), endosulfan, dieldrin, oxychlordane, cis-heptachloroepoxide and p,p"-DDT. A linear correlation was observed between the concentrations of these substances in the placenta and breast milk in samples from Denmark and Finland. Due to their high lipophilicity, these pollutants freely penetrate the placental barrier and can threaten the physical and mental development of the fetus. And due to the high fat content in milk, they enter the baby’s body during feeding, which can also negatively affect its development. It is known that the concentration of most of the studied POPs, including DDT and TCDD, in human milk is significantly higher (5 - 50 times) than in cow's milk or in artificial milk formulas based on cow's milk.
So, in the modern world, a person is exposed to DDT from birth. What could this lead to? As the results of numerous studies show, this is no good.
DDT and its metabolites have pronounced estrogenic and antiandrogenic effects. To some extent, this is similar to DDT and the estrogenic fusarotoxin zearalenone. Both of these substances have a very negative effect on the development of the male reproductive system, both in humans and in animals. When ZEA and DDT enter the body of males, they primarily interfere with the normal formation and development of the gonads.
Figure 3. The effect of DDT and zearalenone on the development of testicles in roosters.
It is advisable to take this circumstance into account when maintaining replacement young stock and parent stock. In addition, DDT causes thinning of egg shells, reducing hatchability and quality of chickens.
In humans, DDT has been found to cause a decrease in weight and anogenital distance in newborn boys, an increase in the risk of developing testicular carcinoma, a decrease in the size of the testicles and prostate gland, a decrease in ejaculate volume in sexually mature men, and a reduction of up to 2 times in the concentration of sperm in seminal fluid. All these manifestations together can lead to a decrease in sexual activity and cast doubt on the possibility of having offspring.
More recently, it was found that DDD is associated with weight gain and the development of type 2 diabetes, increased blood pressure and levels of “bad” cholesterol in the blood, an increased risk of developing breast cancer in young women, as well as an increased risk of having a child. with signs of autism in mothers exposed to DDT.
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According to experts, every year from a third to a half of the world's food supplies are consumed or damaged by insects, molds, rodents, birds and other pests that destroy the crop both in the field and during its collection, loading, transportation and storage. If we successfully combat insects and diseases that attack grain crops, the annual increase in harvest would be about 200 million tons of grain, which would be enough to feed 1 billion people.
Swiss chemist Paul Müller, head of the Geigy laboratory, discovered remarkable insecticidal properties in (later known as DDT) in 1938, and 10 years later he was awarded Nobel Prize in biology and medicine. Indeed, already the first results of the use of this “miracle weapon” were simply stunning - an increase in productivity, the introduction of economical methods of farming, new effective means combating insects that carry infections. During World War II, DDT was used against the lice that spread typhus. As a result, it was the first of the wars in which fewer people died from typhus than from enemy bullets. The use of DDT against mosquitoes that carry malaria has dramatically reduced mortality from this disease. If in 1948 more than three million people died from malaria in India alone, then in 1965 not a single death from malaria was recorded in this country. It was thanks to DDT that millions of lives were saved in this way, and it was for this that Müller rightfully received the Nobel Prize.
However, two or three decades later, the negative environmental consequences of the thoughtless use of DDT and many other pesticides became clear. DDT is an agent whose use has led to global environmental pollution. It has been established that the influence of DDT on the environment is geographically much wider than the territory of its direct application as a result of transitions from soil to water and air, from air to water, etc., transfer by biota, air masses and ocean currents. Thus, today the pollution of the natural environment with this insecticide has become widespread; DDT has been found even in Antarctica.
The problems associated with DDT and other synthetic (particularly chlorinated) pesticides can be summarized as follows:
1) development of pest resistance to these drugs;
2) stability of pesticides in the environment and their accumulation in increasing concentrations in organisms;
3) revival of pests and secondary outbreaks;
4) increase in material costs for the use of pesticides;
5) undesirable effects on the environment and human health. In these aspects, it is advisable to consider the negative environmental consequences of such compounds.
Populations of insect pests are variable; their gene pool is quite dynamic and capable of evolving quite quickly. Pesticide treatment creates pressure natural selection, leading to population stability. When exposed to pesticides, the most sensitive individuals die first, and the resistant ones survive, which also produce a more resilient generation. All this happens very quickly, since the ability of many insects to reproduce is simply phenomenal - they can produce numerous offspring over short periods of time. Thus, repeated exposure to pesticides leads to the selection and propagation of lines with high resistance to precisely those drugs that are created to destroy them. There are known cases when the resistance of insect populations to chemicals increased tens of thousands of times. About 25 major insect pest species have become resistant to all pesticides. Moreover, having acquired resistance to one agent, a population becomes resistant to other substances, even those not related to such an agent, and even if this population has not been exposed to them. It should be noted that the number of insect species resistant to pesticides almost doubled over the first 10 years of intensive use of pesticides - from 224 to 428.
Another aspect of the problem is related to the fate of pesticides in the environment. Chlorinated (such as DDT, Lindane, Kepone, Aldrin and many others) or Hg-, As-, Pb-containing pesticides are very stable. This means that they break down very slowly (or even not at all) when exposed to the sun or bacteria. The persistence of a pesticide in the environment is judged by the time during which it remains in the soil after application: rapidly degrading - less than 15 weeks, moderately degrading - 15-45 weeks, slowly degrading - 45-75 weeks and stable - more than 75 weeks. DDT has a half-life of approximately 20 years. Elements such as mercury and arsenic do not completely decompose - they circulate through ecosystems or end up buried in silt. The vast majority of the most well-known pesticides tend to accumulate in living organisms, not only in quantities greater than those found in the environment, but also in concentrations that increase as they move up food chains. This is called the biological enhancement effect. Despite the fact that information about the impact of pesticides on communities of organisms and the functioning of ecosystems is limited and not systematized, it is noted that due to their high bioaccumulation capacity and low degree of decomposition, they can have an adverse effect on organisms at all trophic levels, especially on highly sensitive primary producers. It is known that the algae Cladophora extracts so much DDT from water in three days that its concentration increases 3000 times. DDT was used to kill mosquitoes on one of the Californian lakes. After treating the water area, the concentration of DDT in the water was 0.02 ppm (parts/million), in plankton - 10, in planktivorous fish - 900, in predatory fish - 2700, and in birds feeding on fish - 2100 ppm, i.e. The content of DDT in the tissues of birds that were not directly exposed to the insecticide was almost 100 thousand times higher than its concentration in water. One kilogram of fat from seals living off the British coast contains 10-40 mg of DDT. Insensitive to the effects of DDT, earthworms are peculiar traps for this substance, actively absorbing it from the soil and accumulating it in the body. When studying the accumulation of DDT and its transitions along the links of the food chain using the example of the Lake Michigan ecosystem, it was found that bottom sludge contains 0.014 mg/kg, bottom-feeding crustaceans - 0.41, various species of fish - 3-6, and adipose tissue for seagulls feeding on this fish – over 2400 mg/kg. German scientists Dymen and Hayes present the following calculation, which is based on a simple rule, according to which in each subsequent link of the food chain the DDT content increases 10 times: silt - x 1, aquatic plants - x 10, daphnia and other crustaceans - x 100, small fish - x 1000, predatory fish - x 10000. This is a demonstrative example of the sequential concentration of DDT. A simple classification of pesticides to determine their safety is presented in Table 13.
Table 13 - Indicators* characterizing the relative toxicity, persistence and bioaccumulation of some pesticides
*) – the degree of toxicity of a pesticide is based on LD50, the persistence of a pesticide in the environment is indicated by the time during which it remains, and the accumulation of pesticides indicates bioaccumulation. On a scale of 1 to 4, the highest rating corresponds to the greatest toxicity, or stability, or the most pronounced potential for accumulation.
The information presented here answers the question: “Why are the costs of using pesticides increasing?” The resistance of pest species that occurs after a series of pesticide treatments, the revival and secondary outbreaks of their numbers, lead to the beginning of the synthesis and use of new drugs that are more expensive to produce. In addition, pesticides already known and previously used in the same territory are used in ever increasing volumes and more often. In particular, some areas of the United States had to abandon cotton cultivation due to the fact that pest control costs exceeded the value of the crop.
Some scientists, trying to find a way out of the situation, have high hopes for the so-called. unstable pesticides. But this path is a dead end and, from an environmental point of view, such hopes are unfounded. The fact is that these unstable pesticides are often more toxic and require more frequent use. In addition, such pesticides also have long-term undesirable effects, so it is naive to consider them “environmentally safe”. An indicative example is the attempt to destroy the caterpillars of the spruce budworm in one of the regions of Canada. To combat pests, an organophosphate pesticide from the “unstable” group was used and was considered environmentally harmless. But as a result of its use, 12 million birds died; they died both from direct poisoning and from lack of food (caterpillars), since they had to eat almost as much per day as they weighed. If insects that feed on phytoplankton die as a result of exposure to such pesticides, the population of the latter will explode. In addition, some beneficial insects, such as bees, may be more sensitive to unstable pesticides than their pests. And, finally, there is no reason to hope that as a result of exposure to these compounds, pests will not develop resistance to them, or secondary outbreaks of the numbers of precisely those organisms against which their action is directed will not be observed.
Perhaps the most important aspect of the problem of pesticides, which was partially discussed above, is their undesirable effects on the environment, ecosystems and human health.
Pesticides are one of the causes of species extinction. As a selection factor, they have the ability to damage the genetic apparatus of the cell and cause mutations. Even small evolutionary shifts ultimately lead to changes in the genetic system of the organism, and then to changes in behavior, which can affect the further course of evolution.
DDT inhibits the photosynthesis of green algae and, given its long existence in the environment, we cannot console ourselves with the hope that seaweed can eventually become an inexhaustible source of food resources for all of humanity. DDT is known to disrupt the numbers of some microorganisms, and this can lead to changes species diversity communities and food chain breaks. The author of the famous book "Silent Spring", the talented biologist Rachel Carson, gives one of the most obvious examples of a simple food chain in which DDT circulates. This is the case with migratory thrushes. The fungus Ceratocystis ulmi causes the so-called. "Dutch disease", which leads to the death of elms. This disease is transmitted by the elm sapwood Scolytes multistriatus, which is controlled by treating trees with DDT. Some of the pesticide is washed off from the elms with precipitation and ends up in the soil. In the soil, DDT is absorbed by earthworms that eat the remains of leaves and it is deposited in their bodies. Migratory thrushes Turdus migratorius, which primarily eat earthworms, were chronically poisoned with DDT in this case. Some of them died, while others lost their ability to reproduce - they became sterile or laid infertile eggs. Ultimately, the fight against Dutch disease led to the almost complete extinction of migratory thrushes in large areas of the United States.
Repeated use of DDT can cause resistance in a number of bacteria. DDT and its metabolites are highly toxic to fish; they disrupt developmental and behavioral processes, have mutagenic and carcinogenic effects, and fish is an important food product. Amphibian larvae are highly sensitive to the effects of DDT and its derivatives, which manifests itself in ethological and anatomical anomalies. The effect of this insecticide on the thickness of egg shells has been studied most deeply. various types birds. It has been shown that DDT, or more precisely its main metabolite DDE, causes thinning of egg shells in mallard ducks, bald eagle, osprey, Japanese quail and other birds. California pelicans, whose eggs contained DDT up to 71 mg/kg, have been unable to reproduce since 1969 and are dying out. A significant reduction in the populations of birds of prey has another consequence - the secondary effect of an increase in the number of rodents, which are destroyed mainly by these bird species.
DDT can cause gender inversion. In one colony of gulls in California, after treating nesting areas with DDT, 4 times more females appeared than males. When DDT was injected into seagull eggs, half of the male embryos turned into female ones.
The effects of DDT on humans are particularly dangerous and clearly not well studied. However, it was noted that in just one decade, from 1970 to 1980, the incidence of pesticide poisoning in the world increased by 250%.
In humans, as well as in many other species, DDT is concentrated primarily in adipose tissue, but is capable of being released with breast milk and even pass through the placental barrier. Just 15 years ago, it was reported that 99% of Americans had 3.6 ppm of DDT and 0.12 ppm of dieldrin in their blood and adipose tissue. According to calculations made in Germany, every infant with mother's milk he receives twice as much DDT as is allowed. The breast milk of nursing American mothers contains 4 times the legal level of DDT. sanitary standards for cow's milk. As one NIH researcher noted, “If human milk had been in a different package, it would not have been allowed to be sold at all.”
When exposed to DDT, people may experience hormonal changes, damage to the kidneys, central and peripheral nervous systems, liver cirrhosis and chronic hepatitis. Despite the virtual absence of genotoxicity, DDT is classified as a carcinogenic risk group 2B. Thus, DDT should be considered as an agent having high level dangers to the environment and human health.
This danger of DDT, like other pesticides, due mainly to their long persistence in the environment, remains relevant to this day, despite the fact that already in the early 1970s a ban was imposed on the production and use of some pesticides. The first country to ban DDT was New Zealand. The USSR was the second country, but this prohibition had two reservations: use was permitted in Uzbekistan, where cases of malaria still occurred, and in taiga regions, where clearings of forests for temporary settlements created clearings in which mice multiplied, and after them ixodid ticks, creating a hearth tick-borne encephalitis which can be effectively combated with DDT. When in the United States the concentration of DDT in the milk of nursing mothers, as a result of the transfer of this substance through the food chain, reached a level four times higher than the maximum permissible limit, the use of DDT was banned. (At least 10 pesticides are banned in the United States—Aldrin, Strobane, DDT, 2,4-D, Toxaphene, Heptachlor, Lindane, Kepone, 2,4,5-T, and Endrin—but a number of them continue to be exported to developing countries). It should be noted that the US supplies about 30% of the pesticides used in the world. However, the ban on DDT is not universal. In Australia and China it is still used to this day for spraying orchards and plantations, and India continues to produce it.
The total amount of banned and obsolete pesticides is 13.4 thousand tons. Physical state them, the uncertainty of the chemical composition, and not always satisfactory storage conditions, pose a potential danger to the environment and human health. To date, their disposal has practically not been carried out. (The largest accumulation of such pesticides is in the territories of Voronezh, Kursk, Rostov, Smolensk, Saratov, Belgorod regions and the Republic of Bashkortostan).
DICHLORODIPHENYLTRICHLOROETHANE (DDT; syn.: gesarol, dicofan, duotex, neocid, pentachlorin, pentacid, drug CC-5, chlorphenothane), 4,4"-dichlois an insecticide that is highly toxic to most arthropods.
Synthesized in 1874; insecticidal properties were discovered in 1939. The pure preparation is a white crystalline substance with a faint aromatic odor; t° pl 108.5-109°, t° boil 185° at 1 mm Hg. Art. Insoluble in water, highly soluble in organic solvents. The 4.4" isomer has insecticidal properties, the content of which is 75-76% in DDT; t° pl 74.5-93°; slightly volatile. Extremely resistant to environmental factors. DDT is a contact-intestinal insecticide. Used in the fight against arthropods carriers of pathogens of infectious diseases.Produced in the form of 5.5% dust, 30% wettable powders, 20% mineral-oil emulsion concentrate, 50% paste.
DDT is a lipotropic poison, it penetrates completely into tissues and organs, especially those rich in fats, and is excreted from the body in feces and milk, and to a lesser extent in urine; has pronounced cumulative properties.
In the mechanism of toxic action, tissue hypoxia and the accompanying disturbance of energy metabolism apparently play a leading role. DDT causes functional disorders not only in the c. n. pp., but also directly in its nerve fibers, as well as in the receptors of the skin and skeletal muscles. The toxic dose for humans is 10-15 mg/kg, lethal - 70-85 mg/kg. Acute intoxication is characterized by headaches, dizziness, pain in the extremities, nausea, vomiting, pain in the upper abdomen, tachycardia, shortness of breath, tremor, convulsions, coma. Death from respiratory arrest in especially severe cases occurs within 1-2 hours.
First aid: induction of vomiting, gastric lavage, saline laxative, siphon enemas, subcutaneous administration of fiziol, solution and sedatives, if necessary - drugs that stimulate breathing and heart activity (adrenaline cannot be administered), in case of severe agitation - chloral hydrate in an enema. Symptoms of chronic poisoning: loss of appetite, dizziness, headaches, rapid mental and physical activity. fatigue, convulsive pain in the limbs along the nerve trunks, polyneuritis, emotional instability, palpitations, shortness of breath, pain in the right hypochondrium. Hron, poisoning is accompanied by hepatitis, gastritis, bronchitis, and functional kidney disorders. DDT can cause an allergic condition, which increases sensitivity to repeated exposure. In case of contact with eyes, it causes severe pain, conjunctivitis, ophthalmia. Eczematous skin lesions of an allergic nature are possible. DDT passes through the placenta. The presence of DDT in women's milk leads to the accumulation of the insecticide in the child's body, which negatively affects the development of the child.
Treatment symptomatic with the use of desensitizing agents. For those who have suffered acute and chronic poisoning, a diet enriched with lipotropic substances, calcium salts, and vitamins is recommended.
In the tissues of deceased people who were in contact with the pesticide, a significant content of DDT and its metabolites was detected, the largest amount in the bone marrow, subcutaneous tissue and omentum.
Gig. standards: maximum permissible concentration (MPC) in the air working area- 0.1 mg/m 3, in domestic water - OD mg/l, permissible residual quantity (RQ) in vegetables and fruits - 0.5 mg/kg, in tobacco - 0.7 mg/kg, in other products , including in milk, butter, meat, eggs, berries - DDT content is not allowed.
The widespread use of DDT in various areas of agriculture has led to the contamination of food products of plant and animal origin.
Stability in the environment and pronounced cumulative properties, the ability to be excreted from the body with milk, to cause chronic diseases in minute quantities, and poisoning served as the basis for the prohibition in the USSR of treating cattle with DDT preparations (1962) and fruit-bearing crops. DDT was excluded from the “List of chemical and biological means of controlling pests, diseases and weeds recommended for use in agriculture of the USSR.”
DDT in forensic medicine
DDT can cause acute poisoning, which should be kept in mind when conducting forensic medicine. examination. When a person is poisoned with DDT, the characteristics of the wedge, pictures, agitation, convulsive muscle contractions, and digestive disorders are important.
An external examination of the corpse does not reveal any characteristic changes.
At court medical autopsy reveals degeneration of cells and nuclei of c. n. pp., degeneration and necrosis of liver cells, swelling of the kidneys, pinpoint hemorrhages under the epicardium and endocardium, myodegeneration of muscle fibers, hyperemia and hemorrhages in the brain, lungs, trachea.
For forensic medical conclusions about DDT poisoning are of great importance data on its determination in the organs of a corpse, taking into account its possible accumulation in the body during life.
The determination of DDT in cadaveric material is carried out by extraction with an organic solvent (ether) followed by reactions of chlorine elimination when heated with an alcohol solution of caustic alkali or hydrogen. The resulting polynitro derivatives are detected by reaction with a solution of sodium methylane in methanol - the reaction product is colored blue-violet. Quantitative determination is carried out argentometrically by the amount of separated chlorine in different conditions. It is also recommended to use gas chromatography.
Harmful substances in industry, ed. N.V. Lazarev and E.N. Levina, part 1, p. 330, L., 1976; Mayer-Bode G. Pesticide residues, trans. with German, p. 203, M., 1966; Melnikov N. N. Chemistry of pesticides, p. 85, M., 1968; Shvaikova M. D. Forensic chemistry, p. 78, M., 1965; Shitskova A.P. and Ryazanova R.A. Hygiene and toxicology of pesticides, p. 87, M., 1975.
L. I. Medved; A. F. Rubtsov (medical court).
