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54 Cards in this Set
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- Back
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Agents of Environmental Diseases
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1. biological and microbiological agents:
zoonotic and vector-borne diseases 2.Chemical agents: toxic metals and elements, and pesticides and other organic chemicals 3. Physical agents: ionizing and non-ionizing radiation |
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Advantages of Hazardous chemicals
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-essential to the functioning of modern society
-15,000 chemicals are made and used in high volume in the United States for manufacturing clothing, phones, computers, cars, building materials, rugs and other furnishings |
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Disadvantages of Hazardous chemicals
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-implicated as human health hazards, for example, in the etiology of cancer and adverse birth outcomes
-Silent Spring, written by Rachel Carson in 1962 is credited with sensitizing the public to the potential hazards of chemicals that were being disseminated into the environment. |
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Aromatic Compound
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-an organic molecule that contains a benzen ring, for example Benzene and toluene.
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Hydrocarbon
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An organic compound (as acetylene, benzen or butane) containing only carbon and hydrogen and often occurrring in petroleum, natural gas, coal and bitumen.
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Organic chemical
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-Naturally occurring (animal or plant-produced or synthetic) substances containing carbon, hydrogen, nitrogen, and oxygen.
-ordinary table sugar is an example of an organic chemical |
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Persistent Organic Pollutants (POPs)
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-Toxic chemcials that adversely affect human health and the environment around the world.
-Because they can be transported by wind and water, most POPs can and do affect people and wildlife far fro where they are used and released. -An example is the pesticide DDT |
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polycyclic aromatic hydrocarbons (PAHs)
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-A group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, garbage or other organic substances like tobacco or charbroiled
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Volatile organic compounds (VOCs)
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Organic compounds that evaporate readily into the air
-VOCs include substances such as benzene, toluene, methylene chloride, and methyl. |
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Pesticide
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"any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating pests. Pests can be insects, rodents, weeds, and a host of other unwanted organisms.:
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Fumigant- a pesticide vaporized to kill pests. Used in Buildings and greenhouses.
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Nematocide
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A chemical agent that is destructive to nematodes
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Herbicide
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A chemical pesticide designed to control or destroy plants, weeds or grasses
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Four major classes of pesticides and insecticides derived from organic chemicals
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1. organophosphates (OPs)
2. Organocarbamates (also called carbamates) 3. organochlorides (also known as organochlorines) 4. Pyrethroids (from the class of pyrethrins) |
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Organophosphate Pesticides
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Can be used to control a wide range of insects, thus eliminating the need for multiple applications of different pesticides
-tend not to persist in the environment -frequent cause of fatal poisonings |
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Effects of organophosphate poisoning
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acute effects: anticholinesterase activity happens soon after exposure and causes impairment of neural impulse transfer mechanism
long term effects: may include a condition known as organophosphate-induced delayed polyneuropathy, which is manifested by numbness, loss of sensory abilities and weakness. |
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Examples of organophophate pesticides
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-diazinon, malathion, methyl parathion, and parathion
-appear in a wide variety of products: sprays, baits, indoor foggers, bombs, flea collears, pet shampoos, powders, animal dips, and granules -Malathion has been approved for direst application to food crops uch as fruits (e.g., apples and grapes), row crops, and vegetables (e.g., tomatoes) |
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Carbamates
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-close relatives of the organophosphate pesticides
-dissipate quickly from the environment asa result of breaking down into other substances -some are approved fro controlling garden pests (e.g., wasps,hornets, and snails). -An ingredient in some products applied to furry pets to control ticks and fleas |
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Examples of Carbamates
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-Carbaryl (Sevin)
-Aldicarb -Fenoxycarb (insect growth regulator) -propoxur -metam sodium |
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Methyl Isocyanate (MIC)
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An Intermediate chemcial used for the manufacture of carbamate pesticides
-when acute exposure occurs, MIC is extremely toxic to life forms (e.g., human beings, aquatic organisms, and plants). |
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MIC release in Bhopal, India
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-A notorious incident was the accidental release of MIC during a 1984 industrial accident in Bhopal, India, that killed more than 3800 people.
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Organochlorines
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-derived from chlorinated hydrocarbons, which are chemical compounds that contain chlorine, carbon, and hydrocarbon
-Characteristically stable and fat-soluable; persist in the environment and bioaccumulate in the food chain. -associated with suppression of the immune system and cancer |
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Examples of organochlorine pesticides
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-DDT
-Lindane -Chlordane -Mirex -Hexachlorobenzene -Methoxychlor |
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DDT (Dichlorodipehnyltrichlooethane)
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-Widespread use of DDT began during the early 1940s and reached a maximum during the 1960s
-due to concerns about the possible adverse effects upon the health of humans and wildlife, application of DDT was prohibited in 1972 in the U.S. -Most developed nations banned the use of DDT; however, some countries still continue to use DDT. |
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Facts about DDT
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-not regarded as a highly toxic pesticide
-formerly employed worldwide to control insects and harmful mosquitoes that carry malaria -was credited at one time with saving millions of people from death due to Malaria. |
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Facts about DDT
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-Concentrates in the adipose (fatty) tissues of the body
-estimated half-life of approximately 10 years -all living organisms on earth contain some levels of this pesticide |
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Human Health effects of DDT
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Linked to:
-cancer (pancreatic, non-Hodgkin's lymphoma, and breast) -repoductive effects -impaired lactation -falling sperm counts -impaired neurologic function (irritability, dizziness, and numbness) |
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Pyrethrins
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-derived from natural sources--certain varieties of chrysanthemum flowers
-have great ability to paralyze and kill flying insects -interfere with transmission of neural impulses via action on sodium channels. |
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Use of Pyrethrins Insecticides
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-Generally have low concentrations of the active ingredient
-use inside the home in aerosol cans, insecticide bombs, insecticidal pet shampoos, treatments for lice applied directly to humans and mosquito repellents. -may be inhaled as a result of spraying and may be ingested in foods. |
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Herbicides/Defoliants
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-Examples of chemcials in the category of herbicides and defoliants are:
-atrazine -paraquat -Agent Orange (2, 4, -D and 2, 4, 5, -T) |
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Agent orange
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Used during the vietnam war, during operation Ranch hand (1962-1971)
-Approximately 19 million gallons of defoliants sprayed on 3.6 million acres in Vietname and Laos -contained small amount of dioxins |
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Health effects of Agent orange
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The institute of Medicine (U.S.) concluded that Agent orange was associated with several forms of cancer:
-soft tissue sarcoma -Non-Hodgkins's lymphoma -Hodgkin's disease -Chronic lymphocytic leukemia |
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Pesticide exposure: Who is at risk?
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-Agricultural workers
-pets -children -livestock -sensitive subpopulations (e.g., pregnant women) |
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Biopesticides
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-pesticides derived from natural materials such as animals, plants, bacteria, and certain minerals
Examples: -microbial pesticides -plant-incorporates protectants -biochemical pesticides |
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Dioxins
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"a family of chemcial compounds that are unintentional byproducts of certain industrial, non-industrial and natural processes, usually involving combustion."
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Facts about dioxins
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-a total of 419 compounds in the dioxin family are known to exist.
-scientists regard only about 30 of these as being the most poisonous -stable, persistent, and bioaccumulate within the food chain. |
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What natural events produce dioxins?
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-Forest fires and volcanic eruptions emit dioxins into the environment
-dioxins that originate from these sources are caleld "natural background" dioxins |
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What human activities produce dioxins?
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-incineration of industrial and municipal wastes
-burning of some fuels -bleaching of wood pulp for paper manufacturing process -manufacture and application of some herbicides -tobacco combustion, which gives rise to minue amounts of dioxin in cigarette smoke |
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Health effects of exposure to dioxin depend on:
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-duration of exposure
-frequency of exposure -when the exposure occurred -concentration of the agent -route of entry into the body |
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Health Effects of Exposure to dioxin include:
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-Chloracne (chlorine acne)
-Skin rashes -skin discoloration -growth of excessive body hair -liver damage -possible cancer risks -endocrine effects -reproductive and developmental effects |
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Polychlorinated Bipehnyls (PCBs)
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Two common uses before their manufacture was terminated
-insulating fluid in transformers and capcitors -lubricant PCBs present in the environment tend to bioaccumulate in fish and other animals used for food and in turn, impact human health. |
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PCB contamination
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PCBs are known to be present at as many as 500 sites denoted on the 1,598 sites that the EPA has provided on the National Priorities List.
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Because of concerns about their environmental and health effects, the manufacture of PCBs was terminated in 1977
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Health Effects of PCBs
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-Cause cancer in animals and are designated probable human carcinogens.
-May impact the immune system, reproductive system and children's intellectual development -may limit the development of immune responses to the Epstein-Barr virus and other viral and bacterial infections. |
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Organic solvents
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"A liquid substance capable of dissolving other substances; the solvent does not change its state in forming a solution."
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Solvents: Modes of Exposure
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-breathing their vapors directly
-ingesting them in foods and water -using foods and cosmetics packed in certain types of plastics -smoking cigarettes -working in a factory: chronic exposure -inhaling vapors released by industrial facilities -drinking solvent-contaminated groundwater |
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Examples of Solvents
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Tetrachloroethlene: dry cleaning, a metal degreaser
Trichloroethane: degreasing compounds, household cleaners |
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Trichloroethylene (TCE)
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Grease-dissolving solvent
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More solvents: Toluene, Acetone
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Nail polish, paints, adhesives
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Benzene
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-intermediary chemical for the manufacture of plastics, resins, synthetic fibers
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Chemicals used in Plastics Manufacture: Styrene
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Used for the manufacture of polystyrene resins, which are components of many types of plastics.
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Short-term inhalation of styrene can produce central nervous system effects such as muscle weakness, and problems concentrating on task; irritation of the respiratory tract also can result.
possibly carcinogenic |
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Chemicals used in plastics manufacture: vinyl chloride
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-used mainly for the manufacture of polyvinyl chloride, which is an ingredient in plastic products such as pipes, vinyl siding for houses, plastic coatings, and upholstery.
-classified as a human carcinogen |
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Chemical: Styrene
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Makes: polystyrene resins
possibly carcinogenic |
used in plastics
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Chemical: Vinyl Chloride
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Makes: polyvinyl chloride
classified as a human carcinogen |
used in many plastics, such as pipes and vinyl siding
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Environmental Estrogens
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-Some organic chemicals (e.g., chlorinated hydrocarbon pesticides) may have estrogenic activity.
-sometimes DDT (and its metabolites) is called an endocrine disruptor, meaning that it accts as an antagonist to androgen. |
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Effects of Environmental Estrogens
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-May have abnormal influences on the reproductive systems of exposes humans and animals
-may act as cancer promoters by having influence on the onset of female cancers that are thought to be caused by estrogenic activity. |
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