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Chemical toxicology and ecofriendly polymers


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Toxicology is the scientific study of adverse effects that occur in living organisms due to chemicals. It involves observing and reporting symptoms, mechanisms, detection and treatments of toxic substances, in particular relation to the poisoning of humans.
The environmental friendly materials involve the fields of green chemistry, biodegradable, and bio-based materials at the structural, chemical, and physical level, as well as the utilization of principles to reduce or eliminate hazardous substances in the design, manufacture, and application of chemical products.

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Chemical toxicology and ecofriendly polymers

  1. 1. Chemical Toxicology & Eco-Friendly Polymers
  3. 3. TOXICOLOGY It can be defined as the study of adverse effects of chemicals or physical agents on living organisms. All Chemicals Are Potential Toxicants Paracelsus ( Father of Toxicology) summed up this concept by stating “ All substances are poisons ; there is none which is not a poison. The right dose differentiates a poison from a remedy.
  4. 4. TERMINOLOGY Toxic : This term relates to poisonous or deadly effects on the body by inhalation , ingestion or absorption or by direct contact with a chemical. Toxicant : A toxicant is anything that can produce adverse biological effects.
  5. 5. Toxicity : It describes the degree to which a substance is poisonous or can cause injury. Dose : It is the actual amount of a chemical that enters the body. Response : The biological effects caused by the exposure is called response. TERMINOLOGY
  6. 6. Dose-Response Relationship • It is a relationship between exposure and health effect, that can established by measuring the response relative to an increasing dose.
  7. 7. Toxic Dose (TD) : The dose required to elicit a defined toxic effect in defined percentage of sample population. Effective Dose (ED) : The dose required to have therapeutic or other effect in defined percentage of sample population. Lethal Dose (LD) : The dose required to show lethal effect in defined percentage of sample population.
  8. 8. No Observed Adverse Effect Level (NOAEL) : Highest data point at which no toxic or adverse effect was observed. Low Observed Adverse Effect Level (LOAEL) : Lowest data point at which some toxic effect was observed.
  9. 9. Substance Non-Toxic Dose Toxic Dose Lethal Dose Alcohol (Ethanol blood levels) 0.05% 0.1% 0.5% Carbon Monoxide (%Hemoglobin bound) <10% 20-30% >60% Secobaratial (sleep aid) Blood levels (mg/dL) 0.1 0.7 >1 Aspirin 0.65gm (2 tablets) 9.75 gm (30 tablets) 34 gm (105 tablets) Ibuprofin 400 mg (2 tablets) 1,400 mg (7 tablets) 12,000 mg (60 tablets)
  10. 10. Routes of Entry of Toxicants into the body Inhalation Dermal Contact Ingestion Injection
  11. 11. Types of Interactions Between Chemicals Additive – All chemicals show their respective responses. Antagonism – One chemical reduces effect of other chemical. Potentiation – One chemical increases the effect of other chemical. Synergism – One chemical dramatically increases effect of other chemical
  12. 12. Environment Toxicology is concerned with the biological effects of chemicals that are encountered by man either incidentally because they are in environment or by contact during occupational or recreational activities. A Systematic Toxicant is the one that effects the entire body or many organs rather than a specific site. Organ Toxicants are the toxicants which affect on specific tissues or specific organs.
  13. 13. Benzene is a specific organ toxicant which is primarily Toxicant to blood forming issues. Lead is also a specific organ toxin; however, it has three target organs ( the central nervous system, the kidney and the hematopoietic system).
  14. 14. Outdoor Air Pollutants : Pollutants such as carbon monoxide, carbon dioxide, sulphur oxides and particulates etc. They are produced in largest amount and have the largest chance of producing a toxic effect. Pesticides : It is a chemical that kills plants or animals that are undesirable. Types of Toxicants
  15. 15. Radiations and Radioactive Materials : Radiation is the release and propagation of energy in space or material medium in the form of waves or steam of particles from a nuclear reactor. There are two types of radiations- 1. Ionizing Radiations- it affects the bone marrow, resulting in a decrease in RBC’s , reproductive effects etc. 2. Non-Ionizing Radiations- I is associated with carcinogenic and mutagenic effects like alterations in DNA, skin cancer. Types of Toxicants
  16. 16. 1. Organochlorides -They are pesticides which have large no of actions. They are very stable with low vapour pressure and high lipophilicity. They tend to be stored in body fats and accumulate in successive organisms in food chain. 2. Organophosphate – They are synaptic poisons. They bid to the enzyme called ‘acetylcholinesterase’ and prevent it from transferring the nerve impulse. Types of Pesticides
  17. 17. 3. Cabamates- They acts like organophosphates but their effect is reversible. 4. Pyrenthroids- They bid to voltage gated sodium channel and prevent it from closing thus a continuous nerve impulse is imparted an the body receives continuous tremors. Types of Pesticides
  18. 18. Effects of Pesticides • Effect on Nervous System • They inhibit Energy Production • They effect cuticle production • They affect water balance
  19. 19. Heavy Metals : Heavy Metals are everywhere in nature. They can get into our food cycle by getting absorbed by plants. The main toxic metals are- 1. Arsenic(As) 2. Cadmium(Cd) 3. Lead (Pb) 4. Chromium (Cr) 5. Mercury (Hg) 6. Iron (Fe) 7. Aluminum (Al) 8. Thallium (Th) 9. Plutonium(Pu) These Metal are all toxic if excessive amounts of these are ingested.
  20. 20.  Arsenic causes decrease in production of RBC’s and WBC’s andabnormal heart rhythm, damage to blood vessels.  Short term of barium exposure can cause vomiting, abdominal cramps, diarrhoea, difficulties in breathing, increased or decreased blood pressure, numbness around the face but large amounts of barium intake can cause, high blood pressure, changes in heart rhythm or paralysis and possibly death.
  21. 21.  Cadmium causes kidney diseases, lung damage, and fragile bones.  Lead can effect sperm producing organs , large amounts can cause brain damage and death.  Chromium can cause irritation to the lining of the nose; nose ulcers, asthma.
  22. 22. Chernobyl Disaster The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine (then officially Ukrainian SSR), which was under the direct jurisdiction of the central authorities of the Soviet Union. An explosion and fire released large quantities of radioactive particles into the atmosphere, which spread over much of Western USSR and Europe. The Chernobyl disaster is widely considered to have been the worst nuclear power plant accident in history, and is one of only two classified as a level 7 event on the International Nuclear Event Scale (the other being the Fukushima Daiichi nuclear disaster in 2011).
  23. 23. Chernobyl Disaster The battle to contain the contamination and avert a greater catastrophe ultimately involved over 500,000 workers and cost an estimated 18 billion rubles. The official Soviet casualty count of 31 deaths has been disputed, and long-term effects such as cancers and deformities are still being accounted for.
  24. 24. The Bhopal disaster, also referred to as the Bhopal gas tragedy, was a gas leak incident in India, considered the world's worst industrial disaster. It occurred on the night of 2–3 December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh. Over 500,000 people were exposed to methyl isocyanate gas and other chemicals. The toxic substance made its way in and around the shantytowns located near the plant. Estimates vary on the death toll. The official immediate death toll was 2,259
  25. 25. The government of Madhya Pradesh confirmed a total of 3,787 deaths related to the gas release. Others estimate 8,000 died within two weeks and another 8,000 or more have since died from gas-related diseases. A government affidavit in 2006 stated the leak caused 558,125 injuries including 38,478 temporary partial injuries and approximately 3,900 severely and permanently disabling injuries.
  26. 26. Minamata disease is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect fetuses in the womb.
  27. 27. Minamata disease was first discovered in Minamata city in Kumamoto prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation's chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which when eaten by the local populace resulted in mercury poisoning. While cat, dog, pig, and human deaths continued till 36 years, the government and company did little to prevent the pollution. The animal effects were severe enough in cats that they came to be called "dancing cat fever.“
  28. 28. A Polymer is a chemical compound or mixture of compounds consisting of repeating structural units created through a process of polymerization. The term derives from the ancient Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "parts"), and refers to a molecule whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties
  29. 29. Types of Polymers On the basis of chemical structure : 1. Homopolymer – If a polymer consists of identical monomer, the polymer is called homopolymer. Example – A-A-A-A-A- 2. Copolymer – If a polymer is a mixture of more than one polymer it is called copolymer. On the basis of Polymeric structure 1. Linear 1 2 2. Branched 3. Cross linked 3
  30. 30. Types of Polymers On the basis of chemical structure : 1. Homopolymer – If a polymer consists of identical monomer, the polymer is called homopolymer. Example – A-A-A-A-A- 2. Copolymer – If a polymer is a mixture of more than one polymer it is called copolymer. On the basis of Polymeric structure 1. Linear 1 2 2. Branched 3. Cross linked 3
  31. 31. On the basis of behaviour on heating 1. Thermoplastics : Those polymers which soften on heating and become plastic so that they can be converted into any shape by moulding. 2. Thermosets : Those polymers which change irreversibly into hard and rigid materials on heating. Types of Polymers
  32. 32. On the basis of Tacticity 1. Isotactic: If the side groups of the monomers lie on the same side of the chain, it is called an isotactic polymer. 2. Syndiotactic : If the side groups are arranged in an alternative position, it is called syndiotactic polymer. 3. Atactic : If the side groups are arranged in irregular fashion around the main chain, it is called atactic polymer. Types of Polymers
  33. 33. On the basis of ultimate form of use : 1. Plastics : All the synthetic polymers usually reffered to as plastics they are hard and tough. 2. Elastomers : The polymers which are capable of being stretched rapidly at least 150% of their original length without breaking and return to their shape on release of stress are called elastomers.
  34. 34. Polymer Synthesis
  35. 35. Free Radical Mechanism It involves three steps 1. Initiation – It takes place in two steps in first a free radical species is produced and in second it combines with a single monomer to produce free radical. 2. Propagation – It involves continuous attack on fresh monomer molecules thus additional units are added to monomer unit. 3. Termination – It can be achieved either by addition of two propagating chains or by removal of a hydrogen atom by another chain thus two short polymers are formed.
  36. 36. Free Radical Mechanism
  37. 37. Any change in polymers during its service whether good or bad can be termed as polymer degradation. Types of polymer degradation : 1. Chain end degradation : In this the degradation starts from the chain ends, resulting in release of monomer unit. example – M-M-M-M-M M-M-M-M-|-M M-M-M-M 2. Random Degradation : It takes place at any random point along the polymer chain. M-M-M-M-M M-M-M-|-M-M M-M-M + M-M
  38. 38. THERMAL DEGRADATION Thermal degradation of polymers is molecular deterioration as a result of overheating. At high temperatures the components of the long chain backbone of the polymer can begin to separate (molecular scission) and react with one another to change the properties of the polymer. Thermal degradation can present an upper limit to the service temperature of plastics as much as the possibility of mechanical property loss.
  39. 39. Photo Degradation It is brought about by UV rays. Some of the transparent plastics become yellowish. The UV light has wavelength less than 400 nm. It undergoes homolytic bond fission to give free radicals.
  40. 40. Oxidative Degradation It lead to hardening ,discolouration and surface changes to the polymer. It’s occurrance depends on the structure of the atom. Oxidative degradation of general alkene-
  41. 41. Mechanical Degradation If a polymer is subjected to mechanical stress, the most vulnerable part of the polymer degrades. Rubber is produced by this method.
  42. 42. Biodegradation It is breakdown of polymer by microbial organisms into smaller compounds. The microbes degrade the polymer by enzymatic or metabolic process.
  43. 43. Biopolymers : The polymers which are created by living organisms. These include polymers from renewable resources. Bioplastics : The plastics manufactured using biopolymers are called bioplastics. Example -Polylactide, Polyhyroxybutyrate, Polycaprolactone.