Industrial chemicals and their harmful effects - class-IX

Organic manure is the substance made up of animal and human excreta and plants wastes. Biofertilizer is the fertilizer made up of living or dried microorganism. Natural insecticides are the substance used to kill the harmful insect. It is made up of plant products and microorganisms. They have no negative impact on the environment. While pesticide is the synthetic substance used to kill the harmful pest. It is made of a chemical in factories. It can involve in the food chain and cause harmful effects to the environment.

The accumulation of chemicals in the living cells is known as bioaccumulation. When there is excessive use of the pesticides for the protection of fruits and vegetables against the harmful pests, this may lead to its accumulation in the food products. When these products are consumed, the chemicals deposit in the fatty tissues of the host. The concentration of the chemicals goes on reducing with the increase in the trophic level of the consumers. So, the primary consumers will have more bioaccumulation than the secondary consumers. 

A protective mechanism refers to the biological response where an organism expresses specific genes to produce enzymes that neutralize toxins like pesticides. This helps the organism survive exposure to harmful chemicals.

The question specifically asks about the action of a protective enzyme in the context of pesticides. These enzymes function by chemically breaking down the toxic pesticide molecules into less harmful compounds.

Pesticide resistance occurs when a population of pests evolves to survive exposure to a chemical that previously killed them. This means the effectiveness of the pesticide in controlling that population has decreased.

Non biodegradable pollutants are the pollutants that do not get easily degraded or broken down into harmless material. Common examples of such pollutants are DDT (Dichloro diphenyl trichloro ethane), BHC (Benzene Hexachloride), plastics etc.

A pest is an organism with characteristics of damaging or harming its surrounding environment, as it harms agriculture through feeding on crops or parasitizing livestock. 

The use of persistent chemicals has an effect on the food chain. Chemicals that do not break down are passed from one organism to the next and organisms at higher trophic levels tend to accumulate larger amounts than the organisms they feed on. This situation is known as biomagnification.

Organochlorines are very slowly decomposing chlorinated organic compounds, which are lipophilic (show much affinity for the fatty tissue of animals). Examples of Organochlorines are DDT, BHC, Aldrin, Endosulphan etc. So, the correct option "C" (Organochlorines).

• Trichoderma is the most prevalent culturable soil dwelling fungi. It has no adverse effect on crop plants.
• It is used as bio fungicide and control agent for bacteria and fungi. Hence, it is a broad spectrum pesticide.
• It forms symbiotic association with the roots of the plants and is not found free living in the soil.
• The dried spores of Trichoderma are sprayed on Brassica leaves to kill Alternaria that causes blight of mustard.

Third generation pesticide is defined as biodegradable, water soluble pesticide, which are more toxic.
Analogues of the juvenile hormone (JH) are used as an insecticide, preventing the larvae from developing into adult insects. JH itself is expensive to synthesize and is unstable in light. At high levels of JH, larvae can still molt, but the result will only be a bigger larva, not an adult. Thus, the insect's reproductive cycle is broken.  

Biological control is a bioeffector-method of controlling pests (including insects, mites, weeds and plant diseases) using other living organisms. It relies on predation, parasitism, herbivory or other natural mechanisms, but typically also involves an active human management role.

The allethrins are a group of related synthetic compounds used in insecticides. They are synthetic pyrethroids, a synthetic form of a chemical found naturally in the Chrysanthemum flower.

Griseofulvin is an orally administered antifungal drug. It is used both in animals and humans, to treat fungal infections of the skin (commonly known as ringworm) and nails. It is produced by culture of some strains of the mold Penicillium griseofulvum, from which it was isolated in 1939.

TCDD is 2,3,7,8-tetrachlorodibenzo-p-dioxin, is a polychlorinated dibenzo-p-dioxin.

Bordeaux mixture (also called Bordo Mix) is a mixture of copper(II) sulfate and slaked lime, used as a fungicide. It is used in vineyards, fruit-farms and gardens to prevent infestations of downy mildew, powdery mildew and other fungi. Bordeaux mixture was discovered by P M A Millardert.

The first-generation pesticides, which were used prior to 1940, consisted of compounds such as arsenic, mercury, and lead. These were soon abandoned because they were highly toxic and ineffective. The second-generation pesticides were composed of synthetic organic compounds.

DDT is one of the most famous pesticides in the world, and it has been with us for quite a long time. As a pesticide, DDT was first used during world war II. It was so effective as an insect killer that some called it as the "atomic bomb" of pesticides.

Organophosphate (OP) compounds are the most widely used group of insecticides in the world. Their acute toxicity causes a hazard both to professional and amateur users. OPs were first recognised in 1854, but their general toxicity was not established until the 1930s. Tetraethyl pyrophosphate (TEPP) was the first OP insecticide, which was developed in Germany during World War Two as a by-product of nerve gas development. OPs are all derived from phosphoric acid. They are generally among the most acutely toxic of all pesticides to vertebrate animals. They are also unstable and therefore break down relatively quickly in the environment. So, organo phosphates are more toxic to vertebrates compared to organo chlorine, carbamates and parathion. Thus, option A is correct and other options are wrong.

2, 4-D is a weedicide. 2,4-Dichlorophenoxyacetic acid  is a common systemic herbicide used in the control of broadleaf weeds. It is a synthetic auxin (plant hormone) and one of the most widely used herbicides in the world. 2,4-D is a possible carcinogen per WHO.

Pesticides are chemicals used to eliminate or control a variety of agricultural pests that can damage crops and livestock and reduce farm productivity. The most commonly applied pesticides are insecticides (to kill insects), herbicides (to kill weeds), rodenticides (to kill rodents) and fungicides (to control fungi, mold, and mildew). Most pesticide used these days are not specific in nature. One pesticide can act on more than one type of pest. 

Antifeedants are third generation pesticides. With the essential principles of hormonal insecticides worked out, the third generation insecticide may be just a few years away.

DDT (dichlorodiphenyltrichloroethane) is a colourless, crystalline, tasteless and almost odourless organochloride. It is known for its insecticidal properties. DDT has been formulated in almost every conceivable form, including solutions in xylene or petroleum distillates, emulsifiable concentrates, water-wettable powders, granules, aerosols, smoke candles and charges for vaporizers and lotions. Thus, the correct answer is option C.

Pesticides are the chemical compounds which are used for the elimination of the harmful pests and insects. When the pesticides are used in excess, it results in the degradation of the soil and water quality. These are non-biodegradable compounds which enter the food chain and the concentration increases with the increase in the trophic level. The pesticides accumulation in the tissues causes toxicity in the organisms and leads to death. 

Bordeaux mixture is a combination of copper sulphate and hydrated lime. It is used mainly to control garden, vineyard and farm infestations of fungus.

Due to chronic injection of pesticides like DDT in birds resulted in thinner and weaker shell. The Ca-ATPase pump responsible for transporting Ca which is inhibited by the pesticide and results in less Ca in the shell. Thus , the correct answer is option A. 

Biomagnification is the process where the concentration of toxins increases as they move up the food chain. All listed examples (DDT effects on salmon, Dialdrin effects on deer, and the concentration gradient between trophic levels) are recognized impacts or characteristics of this phenomenon.

The accumulation of chemicals in the living cells is known as bioaccumulation. When there is excessive use of the pesticides for the protection of fruits and vegetables against the harmful pests, this may lead to its accumulation in the food products. When these products are consumed, the chemicals deposit in the fatty tissues of the host. This phenomenon is called bioaccumulation of the chemicals in the living system.

The development of resistant pest strains is a significant drawback of pesticide use, as it renders the chemicals less effective and necessitates higher doses or new chemicals. This is classified as a negative impact of pesticide application.

Integrated Pest Management (IPM) is a strategy that combines various methods to keep pest populations below economic injury levels while minimizing environmental impact. This includes controlling pest numbers and managing the development of resistance.

Both carbamates and triazoles have been studied for their potential to interfere with thyroid hormone regulation in rodent models. Therefore, both are considered to have thyroid-disrupting properties.

A. L. Melander is historically credited with the first documented case of insect resistance to an insecticide, specifically the San Jose scale's resistance to lime sulfur in 1914.

Some of the common pollutants are non biodegradable, e.g : persistent pesticides like organochlorine or chlorinated hydrocarbons like DDT. These chemicals pass into food chains and increase in amount per unit weight of organisms with the rise in trophic level due to their accumulation in animal fats. Higher the trophic level of an organism in the food chain, greater will be the accumulation of pollutant. As these chemicals are persistent and non biodegradable, they pollute air, soil and water and in which ever organism they reach they simply keep on increasing in concentration. The phenomenon is called biomagnification. 

Pesticides are important pollutants of soil. They include insecticides, fungicides, algicides, rodenticides and weedicides. Pesticides are generally broad spectrum and function as biocides. Organochlorines and chlorinated hydrocarbons are an important class of pesticides. The important ones are dichloro diphenyl trichloroethane (DDT), Benzene hexachloride (BHC), aldrin, dieldrin and endrin. They are persistent, fat soluble, and show biomagnification and hence, are harmful to higher trophic level of organisms. Aldrin was used in buildings to protect against insects, such as termites.

Zinc phosphide is a highly potent rodenticide. It has a wide range of uses commercially and residentially, including the protection of food crops and grasses. As a rodenticide, it can kill mice and voles and also be used as a fumigant in storehouse to control post - harvest pests such as rice weevils, grannary weevils, wheat moths, cotton red bollworms etc.

Bacterial blight is a serious disease of field peas that is caused by the pathogen Pseudomonas syringae. It can be controlled by crop rotation, time of sowing, farm hygiene, sowing disease free seed and using resistant varieties.

Bordeaux mixture was discovered by Pierre Marie Alexis Millardet in 1882. Its a mixture of copper sulphate and slaked lime. Its the most successful fungicide.

Paul Muller discovered that DDT (chemically, dichloro-diphenyl-trichloro-ethane) would kill insects in 1939 and used extensively by the U.S. military during the war. DDT led the way to develop other insecticides and herbicides. 

DDT was banned because of concern over carcinogenicity, bioaccumulation and health effects on wildlife. In addition to these concerns, resistance to DDT occurs in some insects (like the house fly) that develop the ability to quickly metabolize DDT into the lower toxicity breakdown product DDE. DDT affects the nervous system by interfering with normal nerve impulses. DDT causes the nerve cells to repeatedly generate an impulse which accounts for the repetitive body tremors seen in exposed animals.

DDT was used for malaria control at the end of WWII. National Malaria Eradication Programme (NMEP), started an attack phase for indoor residual spraying of DDT which resulted in malaria eradication. As a collateral benefit, DDT eliminated kala - azar and plague and wiped out nuisance of household insects. Such a spectacular success made the use of DDT popular.

DDT is highly persistent in the environment. The soil half-life for DDT is from 2 to 15 years and in an aquatic environment, is about 150 years. Due to slow degradation DDT causes air, soil and water pollution.

Organochlorine pesticides are chlorinated hydrocarbons used in agriculture and mosquito control. Representative compounds in this group include DDT, ethoxychlor, dieldrin, chlordane, toxaphene, mirex, kepone, lindane and benzene hexachloride

Because of DDTs chemical properties, it has the tendency to accumulate in animals. As animals lower on the food chain are eaten by other animals higher up, DDT becomes concentrated in the fatty tissues of the predators. This continues until reaching the primary predator of the food chain, who receives the highest dose of DDT. In food chain seaweed-limpet - crab - seagull, Sea gulls are the predators and snatch the top position of food web.

Malathion is an organophosphate insecticide. It interferes with the nervous system by blocking an enzyme acetyl cholinesterase that normally acts as an off switch by ending the signal. Without the enzyme, the nerve keeps firing and eventually the nervous system fails. Malathion is used both in agricultural and residential settings.

Fumigants are volatile and poisonous substances used to kill insects, nematodes that damage stored foods or seeds, human dwellings, clothing, and nursery stock. Ethylene dichloride is used to treat open storage areas and as soil fumigants. It is a low-pressure compound which diffuses more slowly.

Endosulfan is a broad-spectrum organochlorine insecticide used to control a variety of insects on crops. It falls under the general category of pesticides.

Paul Muller also known as Pauly Mueller was a Swiss chemist who received the 1948 Nobel prize in Physiology or Medicine for his 1939 discovery of insecticidal qualities and use of DDT in the control of vector diseases, such as malaria and yellow fever.

2,4-D is one of the more useful herbicides. This herbicide is selective for broad leaf weeds. This makes it useful to control such weeds as dandelions, plantains, knotweed, pigweed, and many others. It is a systemic herbicide, which means that it is absorbed into the plant tissue and transported throughout the plant, including into the root system.

Pyrethroids are a class of synthetic pesticides used widely in home insect - control products, including flea bombs, roach sprays, ant bait, flea - and - tick pet shampoos, and lice shampoos. Examples of pyrethroid pesticides include: cypermethrin, permethrin, deltamethrin, bifenthrin, and cyfluthrin.

Propoxur is a nonfood carbamate insecticide, marketed under the registered trademark name 'Baygon'.  It is used to control cockroaches, flies, mosquitoes and lawn and turf insects.

Malathion is an organophosphate insecticide that has been widely utilized in public health programs, including antimalarial efforts, to control mosquito populations.

Aldrin is a pesticide used to control soil insects such as termites, corn rootworm, wireworms, rice water weevil and grasshoppers. It has been widely used to protect crops such as corn and potatoe and has been effective to protect wooden structures from termites.

2,4-D (2,4-Dichlorophenoxyacetic acid) is a systemic herbicide that affects the specifically acts on the dicot weeds. It is used in the crop field of cereals to wipe out the weeds without affecting the monocot cereals. 

Allethrin is a synthetic pyrenoid used as an insecticide. These were made in 1949 and their chemical structure bears similarity to the natural pyrenoids obtained from the chrysanthemum plants. These are used to kill the flying and crawling insects in homes and workplaces.

Most synthetic insecticides, such as organophosphates and carbamates, function by inhibiting acetylcholinesterase, which disrupts the normal transmission of nerve impulses in the target pest's nervous system.

Agricultural and horticultural lands are primary sources of pesticide runoff and leachate, which can contaminate groundwater and nearby water bodies.

Lakes downwind from industrial centers are susceptible to acid deposition because industrial emissions (like sulfur dioxide and nitrogen oxides) react with atmospheric moisture to form acids, which then fall as rain or dry deposition.

Auxins are toxic to plants in large concentrations; they are most toxic to dicots and less so to monocots. Because of this property, synthetic auxin herbicides, including 2,4-D and 2,4,5-T, have been developed and used for weed control. Dioxins are environmental pollutants. They belong to the so-called dirty dozen - a group of dangerous chemicals known as persistent organic pollutants (POPs). Dioxins are of concern because of their highly toxic potential. Experiments have shown they affect a number of organs and systems.
Once dioxins enter the body, they last a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body. Their half-life in the body is estimated to be 7 to 11 years. In the environment, dioxins tend to accumulate in the food chain. The higher an animal is in the food chain, the higher the concentration of dioxins.
The chemical name for dioxin is: 2, 3, 7, 8 - tetrachlorodibenzo para dioxin (TCDD). The name "dioxins" is often used for the family of structurally and chemically related polychlorinated dibenzo para dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Dioxins are mainly by-products of industrial processes but can also result from natural processes, such as volcanic eruptions and forest fires. Dioxins are unwanted by products of a wide range of manufacturing processes including smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides.

Pesticides are applied to the soil to manage the weeds. The length of the time that the pesticide remains active in soil is referred to as "soil persistence". Though desirable in the season of application, its persistence in the soils may affect the crop growth and yield. Benzene Hexachloride(BHC) is a chemical compound with several stereoisomers of which one is an insecticide called Lindane and the by-product is β-hexachlorocyclohexane- the pesticide. This pesticide which was used widely to protect cotton plants during 1960 and 1970's is banned as it has high levels of soil persistence and is neurotoxic for the animals. 

Pesticides have had some of their most striking effects on birds, particularly those in the higher trophic levels of food chains, such as bald eagles, hawks and owls. These birds are often rare, endangered and susceptible to pesticide residues, such as those occurring from the bioconcentration of organochlorine insecticides through terrestrial food chains. Pesticides may kill grain and plant-feeding birds and the elimination of many rare species of ducks and geese has been reported. Populations of insect-eating birds, such as partridges, grouse and pheasants have decreased due to the loss of their insect food in agricultural fields through the use of insecticides. Thus, the correct answer is option D.

In 1972, the 'Environmental Protection Agency' banned the use of DDT in the United States as well as the use of pesticides, such as endrin and dieldrin. As a result, the levels of these persistent compounds in the environment have decreased in most areas, thus, the reproductive success of brown pelicans has increased.

Minor pests are the species that feed or oviposit on the crop plants but usually do not inflict damage of economic importance and often their effect on the plant is indiscernible.
A pest is "a plant or animal detrimental to humans or human concerns (as agriculture or livestock production)"; alternative meanings include organisms that cause nuisance and epidemic disease associated with high mortality.

Phytophthora palmivora has been used as an post emergent mycoherbicide to control milkweed or strangler vine, a major problem on citrus in south Florida. It controls the weed by a root and stem rot and girdling the stems of infested plant near the soil surface, resulting in the death of seedlings and the older plants.

Agent orange was a powerful mixture of chemical defoliants used by U.S. military forces during the Vietnam war to eliminate forest cover for north Vietnamese, as well as crops that might be used to feed them. The U.S. program of defoliation, codenamed Operation Ranch Hand, sprayed more than 19 million gallons of herbicides over 4.5 million acres of land in Vietnam from 1961 to 1972.

Bacterial blight is a serious disease of field peas that is caused by the pathogens Pseudomonas syringae pv. pisi and Pseudomonas syringae pv. syringae. 

Malathion is an organophosphate pesticide that acts by irreversibly inhibiting the enzyme acetylcholinesterase, leading to the accumulation of acetylcholine and subsequent nervous system failure in the pest.

Aldrin is an organochlorine insecticide that was widely used until the 1970s, when it was banned in most countries. It is a colourless solid. Before the ban, it was heavily used as a pesticide to treat seed and soil. It is a chlorinated hydrocarbon. Thus, option C is correct. A carbamate is an organic compound derived from carbamic acid (NH2COOH). Thus, option D is wrong. Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity. It is not a chlorinated hydrocarbon. Thus, option A is wrong. Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum which are cultivated as ornamentals for their showy flower heads. Thus, option B is wrong. 

Organochlorine pesticides are highly lipophilic, meaning they are fat-soluble. This property allows them to accumulate in the fatty tissues of organisms and biomagnify through the food chain.

Most of organochlorine pesticides are highly soluble in fat of animals. Further, these chemicals are resistant to be metabolized, so they start accumulating in the bodies of animals. 

Malathion is an organophosphate parasympathomimetic, which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity. Malathion is a parasympathomimetic organophosphate compound that is used as an insecticide for the treatment of head lice. It inhibits acetylcholinesterase activity of most eukaryotes. Malathion is toxic to aquatic organisms, but has a relatively low toxicity for birds and mammals. 

Polychlorinated biphenyls are a group of man-made chemicals useful in a variety of industrial processes, including the insulation and cooling of electrical equipment. But PCB pollution continues long after its source is cut off. PCBs are still found in the Great Lakes through a process called atmospheric deposition. Pollutants like dioxins and PCBs enter from the air into the water through rain and snow, falling particles, and absorption of the gas form of the pollutants into the water.  Dioxins are chemically similar to PCBs. Lake and river sediments are especially good at holding onto PCBs, so bottom-dwelling fish tend to have higher levels.

Herbicide carbamatets are asulam (thiocarbamate), carboxazole, chlorprocarb (phenyl carbamate), dichlormate, fenasulam, karbutilate, terbucarb.

The allethrins are a group of related synthetic compounds used in insecticides.

Atrazine, a triazine herbicide, is used in corn and sorghum for control of broadleaf weeds and grasses. Still used because of its low cost and because it works well on a broad spectrum of weeds common in the US corn belt, atrazine is commonly used with other herbicides to reduce the overall rate of atrazine and to lower the potential for groundwater contamination; it is a photosystem II inhibitor.

Insecticides based on their target sites and mode of action at the target sites can be classified into neurotoxins and others which do not target the nervous system of the insects. Insects have highly specialised interconnected cells nervous system along which electrical charge (impulse) travel. Neurotoxins target the enzymes involved in neurotransmission. The prolonged and irreversible disruption of a normal functioning nervous system may result in death.

Herbicides of photosystem-II inhibit the reduction of plastoquinone at the secondary quinone acceptor site and its subsequent re-oxidation. This consequently light induces charge separation which leads to recombination processes. This process generates reactive oxygen species causing extensive damage in PS II and eventually kills the plant.

Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colourless, tasteless, and an almost odourless crystalline chemical compound, an organochlorine, originally developed as an insecticide, and ultimately becoming infamous for its environmental impacts. Opposition to DDT was focused by the 1962 publication of Rachel Carson's book Silent Spring. It catalogued environmental impacts that coincided with the widespread use of DDT in agriculture in the United States, and it questioned the logic of broadcasting potentially dangerous chemicals into the environment leaving the residues for a long time.

Weedicides or herbicides are weed killers or pesticides used to control weeds in agricultural farms. AMO 1618  or (2-isopropyl-5-methyl-4-trimethylammonium chloride)-phenyl-1-piperidine carboxylate is an  inhibitor of gibberellin biosynthesis which leads to retarded germination. Higher concentrations will lead to  reduced sensitivity of seeds.