Pesticides and herbicides.pptx

Pesticides and herbicides

1. PESTICIDES AND HERBICIDES PRESENTED BY- SAKSHI PATIL AEM-MA-09-06 SUBMITTED TO: SAURAV KUMAR SUBMITTED BY: SAKSHI AEM-MA-09-06

2. Introduction G rowing demand for food as a result of increasing population has led to a substantial increse in the production of agro-chemicals like pesticides and fertilizers, resulting in a continued contamination of our environment including water bodies. W idespread contaminations of the environment by pesticides has been reported and sooner or later a large fraction of these contaminants find their way into various aquatic ecosystem. T her e fore it is imp ortant to study the pr o bl e m of pesticide pollution and to find ways and means for the safe use and control of pesticides.

3. Pesticide Any material that is used to kill a pest is pesticide. Pests are destructive organisms (insects, bacteria) that affect crops, food, livestock, health, etc. P est is any organism that compete for food or living space . C ide -Latin word " to kill ." According to the law, a pesticide is any substance "intended for preventing, destroying, repelling, or mitigating any pest."

4. Classification of pesticides M ethod of classification E xamples B y target insecticides, herbicides, fungicides, rodenticides, algicides, nematociddes B y chemical nature natural organic compound ,inorganic compunds, chlorinated hdrocarbons, organophosphate, carbamates B y physical state dusts, dissolve solutions, suspended solutions, volatile solids B y mode of action contact poisons, fumignats, stomach poisons

5. Types of Pesticide I nsectides T hose compounds that are effective against insects. M ost of the insectides are applied as a spray, others are applied as a dust , aerosol . T he majority of insecticides used today are synthetic organic chemical and most of them are nerve poisons. T hey act by inhibiting the organisms enzymes or interacting with other target sites vital to the porper functioning of the insects's nervous system.

6. 1. C hlorinatetd hydrocarbon They are a lso called organochlorides, were the first commercial organic insecticide to b e developed. eg: DDT, dieldrin, Aldrin, endrin etc. DDT (D ichloro-diphenyl-trichloroethane ) It is applied to a variety of agriculture crops, providing enormous success in pest control. It is also used to control dieases carrying insects such as moisquitoes that spread malaria.

7. Contd.. When DDT 's environmental consequences became evident, its use was either limited or totally banned in industrialized countries. Characterstics It has a very low vapour pressure It is extremely low solubility in water High solubility in oils

8. Contd.. DDT can be readily absorbed through the skin in the fatty tissues of living organisms and can biomagnify the tissue as pass through the food chain.

9. Contd.. Effects It blocks normal nervous system of fish eating birds.(eagles, Ospreys, Pelicans etc…) Interferes with calcium deposition during the formation of egg shell in marine birds .

10. 2.Organophosphorus compound They are most toxic among insecticide. They are dangerous not only to insects but also to mammals. Examples: parathion, malathion, timet etc. Symptoms of poisoing by organophospahte insecticides in humans include vomiting, cramps, sweating, blurred vision, severe cases may fatal with respiratory failure.

11. Contd.. Organophospahte are more toxic than chlorinated hydrocarbons as they are more easily biodegraded than the organochlorines. Organophosphate do not persist in the environment or accumulate in fatty tissue. The mode of action of this group is the inhibition of AChE (acetylicholinesterase).

12. 3.Carbamates These are derivatives of carbamic acid, HO-CO-NH2 It is widley used for worm control on vegetables. Example: aldicarb (trade name:temik) . Mode of action is same as that of organophosphates.i.e, inhibition of AChE.

13. ACh E inhibitio n

14. Action of ACh E and ACH

15. Herbicides It is used for kill or inhibit the growth of unwanted plants. Example : 2,4-D , Diquat , Chlorophenoxy , Acetanilides etc. Numerous clinical reports on humans have dsecribed peripheral neuropathy (degeneration of nervous tissue) and acute myopathy ( disorder of muscle tissue or muscles). Clinical symptoms of severly poisoned farmer include pain , twitching, mucsle spasms.

16. Fungicides Fungicides are pesticides that kill or prevent the growth of fungi and their spores. They can be used to control fungi that damage plants . F ungicides bind with specific enzymes to interrupt the metabolic pathways involved with cellular respiration. Example : Thiocarbamates, Cupric salts, Triazoles etc.

17. Rodenticides Rodenticides are pesticides that kill rodents. Rodents include not only rats and mice, but also squirrels, rat, woodchucks. They can damage crops, transmit disease, and in some cases cause ecological damage . Example : Warfarin, Chlorphacinone, Diphacinone etc.

18. Pesticide cycle

19. Exposure route

20. Contd...

21. Dermal absorption Dermal absorption may occur as a result of splashes and spills when handling (mixing, loading or disposing) pesticides. Pesticides can cross the epithelium of the skin . Skin absorption is higher when there is vasodilatation . Powders, dusts, and granular (dry) pesticides are not absorbed so easily through the skin than the liquid formulations .

22. Contd.. T he seriousness of dermal exposure depends upon: T he dermal toxicity of the pesticide, T he rate of absorption through the skin, T he size of the skin area contaminated, T he length of time the material is in contact with the skin, T he amount and concentration of pesticide on the skin.

23. Ingestion Pesticides entering the body through the mouth may cause serious illness, severe injury, or sometimes even death . These products may be consumed accidenta lly or may be consumed intentionally by individuals who intend on personal harm ( deliberate self-poisoning). Oral exposure can also occur when hands are not properly washed befor e eating. Furthermore, pesticides may be swallowed by mistake. Materials that are ingested can be absorbed along the gastrointestinal tract, with the small intestine being reported to be the major absorption site. Once absorbed, they find their way into the blood stream, through which they are capable of readily distributing throughout the entire body.

24. Inhalation Pesticides entering the body through inhalation can cause serious damage to the nose, the throat, and the lung tissues. The rapid absorption of pesticides through this specific route increases the risk of respiratory exposure. The greatest potential for poisoning via respiratory exposure is with vapours and extremely fine particles of the spray solution. Pesticide exposure is usually low when dilute sprays are applied with common conventional spraying equipment because larger droplet sizes are produced. By contrast, when low volume equipment is utilized to apply concentrated material, the potential for an event of respiratory exposure is increased because smaller droplets are produced. Respirators and gas masks can provide protection from respiratory exposure.

25. Ocular Exposure The tissues of the eye are extremely absorbent. Blood vessels are very close to the surface of the eye, so pesticides can be easily absorbed into the bloodstream. Under certain conditions and using certain pesticides, absorption through the eyes can be significant and particularly hazardous. S ome products are corrosive and can cause severe eye damage or even blindness. Serious eye exposure can result from airborne dusts particles , spray mists, or from rubbing the eyes with contaminated hands, clothing, such as unwashed gloves. Therefore, protective goggles should be used whenever there is a possibility of pesticides coming into contact with the eyes.

26. Sources of pesticides in water Run off from agricultural field Spray drift Rain water I ndustrial effluents Direct application of pesticides to water

27. P esticides residues in water M ost of the survey and data generally refers to organochloride insectides in river . DDT residues were most common and often accounted for the largest amount. T he overall amount of organochloride residues genearlly do not extend beyond one part per billion and such levels normally do not result in any acute toxicity to fish and most other aquatic organism . Generally the pesticides level in the lakes seem to depend upon the size of the lake and also if the sewage or industrial effluents are discharge into them.The higher level of pesticides due to their being surrounded by industrial complexes.

28. P ersistence of pesticides in water T he persistence of pesticides will depend very much on their chemical stability. The stability ranges from very short periods to several years. T he solubility of the pesticides in water will also effect their persistance. The solubilities of pesticide vary greatly. They are easily diluted and are less persistent. O n the other hand relatively insoluble chemicals like DDT are not leached easily and become fractions of the bottom sediment and settle at the bottom.

29. B ioaccumul ation and degradation of pesticide T he pesticide present in the water get concentrated in the tissue of plants and animals. The extent of this accumulation gives an indication of the pesticides transport in food chain and also the potential hazards in the environment. B ioaccumulation depends upon several factors like the lipid/ water partition coefficient environmental conditions and nature of aquatic micorganism. S ome pesticides can be metabolized and degrade by the biota.

30. M inimizing and removing the pesticied residue I t is possible to decrease water contamination. L ess persistent pesticides may be used in placed of highly . Al ternate methods of pest control lilk biological control, attractants etc. may be used. T he industrial effluents containing pesticides can be treated before release into the rivers in various way which will remove almost all of residues. T he treatment involves coagulation, sedimentation, filtration it can remove upto 90% DDT.

31. Toxicity of different pesticides 1. Organochlorines OC compounds are more toxic than organophosphate compounds to fish. Among OC endrin and other cycloidienes (endosulphan) are highly toxic to fish Among OC compounds cyclodienes have high acute toxicity, whereas DDT has a greater chronic toxicity . 2. Organophosphates, carbamtes and pyrethroids OPs have negligible chronic toxicity, but some of them have moderate to high acute toxicity. The chronic toxicity of OP and carbamate compound is low.

32. Contd.. 3. Herbicides Few of herbicides have chronic toxicity. The acute toxicity of herbicides are also low. The major problem arising from the application of herbicides for the control of aquatic weed is not direct but results from the depletion of DO owing to the decomposition of the dead and decaying weeds. Problem with herbicides is the very high quantities that have to be initially used for effe c tive weed control.

33. Sublethal effects of pesticides on fish 1. Morphological ch an ges Darkening of the skin Formation of brown spot on head Swelling of th eyes Erosion of the fin margin Wies reported relationship between acetylcholinesterase( AChe) inhibition and retardation of the fin regeneration.

34. Contd.. 2. Vertebral damage and anatomical changes Induce vertebral damage and skeletal deformities. Darsie and coriden reported that ocellated malathion exposed killifish developed a laterally bent caudal peduncle and bent body. McCann and jasper reported extensive hemorrhaging of the vertebral region. Uncoordinated movement, scoliosis ( lateral curvature of spine) It was suggested tha AChe was responsible for this abnormality.

35. Contd.. 3. General behaviour changes A marked declining in the frequency of various agonostic behaviour ( chasing, vacating, nipping) etc. was noticed . Comfort behaviors like flicks, thrusts, coughs, etc. increased with increasing conc entration of toxicant . At higher concentartion some individuals were unable to maintain position and were swept down stream.

36. Contd.. 4. Swimming and hypersensitivity Aberrant swimming Unusual response to electric field Erractic swimming and slugish feeding Loss in equilibrium

37. Contd.. 5. S chooling behavi ou r Disruption of schooling behaviour due to sublethal stress of toxicants, results in increased swimming activity and entails increased expenditure of energy and hence higher food requirement.

38. Contd.. 6. Learning ability Increase in amplitude and decrease the of spontaneous cerebral activity. 7. Effect on respiration Exposure to sublethal concentration is reported to increased respiratory activity, resulting in increased ventilation and hence, inctease uptake of toxicant.

39. Contd.. 8. Effect on feeding Reduced feeding and decreased ability to preceive the presence of food were evident. More time required to consume certain quantity of food . In absence of contaminants, food odor was attarctive but when the food is contaminated with toxicant, the fish avoided it.

40. Contd.. 9. E ffect on reproduction and fecundity C aused delay in the spawning F ertility of female was reduced F ecundity reduced L ower GSI

41. R efrence https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606636/ https://www.who.int/ceh/capacity/Pesticides.pdf http://npic.orst.edu/ingred/ptype/index.html https://www.who.int/ceh/capacity/Pesticides.pdf Yu.M.H., 2001,Environmental toxicology,187-208 Eastern.W.,1983,Water pollution and mangement, 51-73 Murty.A.S., 2001,Toxicity of pesticides to fish, volume (II)

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