Flashcards
Toxicology - Chapter 3/4 (Toxicant Classes)
Flashcards do conjunto (60)
- 1Anthropogenic examples of the 20th centuryDonora Episode of 1948 - killed 20 and sickened 7K in Donora, PA
London Killer Smog (1952) - estimated 4K deaths above the normal daily count due to respiratory problems (i.e. bronchitis, pneumonia) - 2Carbon MonoxideSource - motor vehicle emissions, burning fossil fuels, and incomplete combustion
Significance - Combines with hemoglobin to form carboxyhemoglobin (poisonous) - 3Particle PollutantsDust
Fumes
Mist
Smoke
Aerosol - 4Natural Air PollutantsVolcano eruptions
Forst Fires
Dust storms
Salt particle aerosol from ocean
Hydrocarbons from trees
Pollen and spores from plants - 5Anthropogenic Air PollutantsCombustion sources
Exhaust emissions
Industrial Processes
Mining and drilling - 6Indoor Air PollutantsCombustion products from heating, cooking, pesticides, tobacco smoking
- 7Which layer of the ozone is considered "bad" ozone? "Good" ozone?Bad - tropospheric ozone
Good - stratospheric ozone - 8What are the six principal pollutants identified by US EPA?Carbon Monoxide
Nitrogen Oxides
Sulfur Oxides
Ozone
Particulate Matter
Lead - 9T/F - Chlorofluorocarbons (CFCs) are the major contributors of damage to the stratospheric ozone layerTrue
- 10Name some common toxicological features of metalsMetal must cross membrane in order to exert toxicity
lipid-soluble metals readily penetrate membranes e.g. methyl mercury
protein bound metals absorbed via endocytosis e.g. cadmium-metallothionein
metals can be absorbed via passive diffusion e.g. lead - 11Major metals associated with toxicityLead, Mercury, Cadmium, Chromium and Arsenic
- 12Define Water PollutionAny physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses
- 13Define and give an example of Point Source pollutionDischarge pollution from specific locations e.g. factories, power plants and drain pipes
- 14Define and give an example of Nonpoint Source pollutionScattered or diffused with no specific location of discharge*
e.g. agricultural fields, feedlots, golf courses, residential construction sites
*Also includes atmospheric deposition (contaminants carried by air currents and precipitated into watersheds or directly onto surface waters) - 15Sulfur OxidesSources - Coal and oil power plants
Significance - Main component of acid deposition - 16Gaseous Air PollutantsCO
H2S
CH4
SO2
CO2
NO2
O3 - 17Carbon DioxideSources - product of complete combustion
Significance - may cause greenhouse effect - 18Nitric OxideSources - Automobile emissions, fossil fuel power plants
Significance - pulmonary edema and impairment of lung function - 19Ozone (O3)Sources - Automobile emissions, photochemical smog
Significance - Damage to vegetation, lung irritant - 20What are the two heavy metals of greatest health concern regarding drinking water exposure?Lead and arsenic
- 21What are the two heavy metals of greatest health concern regarding food chain exposure?Cadmium (responsible for Itai-Itai disease) and mercury (most widespread in North America)
Also, pesticides such as DDT (organochlorine compound) - 22Excess of these nutrients can lead to "algal blooms" or eutrophicationNitrates and phosphates
- 23T/F - One potential adverse health effects of nitrate entering drinking water is anemia or blue baby disease?True
- 24Two most important sources of toxic organic chemicals in water are:1) improper disposal of industrial and household wastes
2) Runoff of pesticides from fields, roadsides, golf courses and lawns - 25Threshold limit values (TLVs)refer to airborne concentrations of substances and represent conditions under which repeated exposure causes no adverse effects
- 26Threshold limit value-time-weighted average (TLV-TWA)concentration for a normal 8-hr workday or 40-hr workweek to which nearly all workers may be repeatedly exposed, day after day, without adverse effects.
- 27Threshold limit value - short-term exposure limit (TLV-STEL)maximal concentration to which workers can be exposed fora period up to 15-min continuously without suffering from irritation, chronic or irreversible tissue change, or narcosis of sufficient degree that would increase accident proneness, impair self-rescue, or materially work efficiency, provided that no more than four excursions per day are permitted, with at least 60min between exposure periods, and provided that the daily TLV-TWA is not exceeded.
- 28Threshold limit value-ceiling (TLV-C)the concentration that should not be exceeded even instantaneously
- 29Biologic limit values (BLVs)represent limits of amounts of substances to which the worker may be exposed without hazard to health or well-being as determined by measuring the workers tissues, fluids, or exhaled breath.
- 30Immediately dangerous to life or health (IDLH)conditions pose a threat of sever exposure to contaminants that are likely to have adverse cumulative or delayed effects on health
- 31T/F - Metals interacting with enzymes may induce toxic action via either inhibition or activationTrue
- 32Carcinogenic metalsKnown: arsenic, nickel, and certain chromium compounds
Probable: beryllium, cadmium, cisplatin - 33What organ is most susceptible to metal toxicityKidney, main excretory organ, is particularly susceptible to cadmium and mercury.
Note: water solubility increases nephrotoxicity - 34Metals can act directly on sex organsAcute cadmium exposure can produce testicular injury
Lead accumulation in the testes is associated with testicular degeneration, inhibition of spermatogenesis, and Leydig cell atrophy - 35How does acute metal exposure differ from chronic metal exposure?Acute metal exposure causes irritations and inflammation of the respiratory tract
Chronic exposure leads to fibrosis or carcinogenesis - 36What is the name of the metal binding protein responsible for regulating the intracellular bioavailability of cadmium, copper, mercury, silver, and zincMetallothionein (MT)
- 37What are the main targets of lead toxicity?Hematopoietic and nervous system
- 38Organic mercury primarily affects the _____ system.nervous system
Note: Elemental mercury absorbed by the respiratory system and permeates the BBB, effecting the nervous system - 39Cadmium inhibits what organelle function?Lysosomes
Note: Very slowly excreted from the body. Long-term exposure damages the kidney. Transported via MT - 40What two forms of chromium are of biological significance?Trivalent (Cr^+3) and hexavalent (Cr^+6)
- 41T/F - High levels of arsenic may result in gangrene of the lower extremities or cancer of the skin?True
- 42What is used to reverse or prevent metal toxicity?Chelating agents - formation of metal ion complex in which the metal ion is associated with an electron donor ligand
- 43How does a "general" use pesticide differ from a "restricted" use pesticideRestricted - generally causing undesirable effects on the environment, applicator, or workers. Can only be purchased by state licensed individuals
General - causes no unreasonable, adverse effects when used according to the label. Can be purchased and applied by anyone. - 44Chlorinated hydrocarbons are _____ and cause acute effects by interfering with the transmission of _____Neurotoxicants; nerve impulses
- 45Published by Rachel Carson in Silent Spring, this pesticide was identified as a neurotoxicant that interferes with the transmission of nerve impulsesDDT
Note: insecticide - 46How do organophosphorus (OP) insecticides exert their toxicity?Via inhibition of acetylcholinesterase
Note: principle site of action is the PNS - 47Carbamates share a similar mode of action to OPs, inhibiting acetylcholinesterase. What is a notable difference between carbamates and OP insecticides?Carbamates are more rapidly reversed than OP compounds
- 48Pyrethroid InsecticidesAffect nerve membranes by modifying the sodium and potassium channels, resulting in depolarization of the membranes.
- 49HerbicidesThe most widely used class of pesticides
e.g. TCDD aka Agent Orange - 50FungicidesRelatively nontoxic
Note: Hydrolyze to produce known carcinogens such as ethylenethiourea (ETU) - 51Examples of food additives and containinantsAntioxidants, fungistatic agents, emulsifiers, stabilizers, humectants, dyes, vitamins, amino acids, inorganics, chelating agents
- 52Microbial toxinstoxic substances produced by microorganisms that are of high molecular weight and have antigenic properties
e.g. Clostridium tetani (tetanus), C. botulinum (botulinum)
Note: toxic compounds produced by bacteria that do not fit these criteria are referred to as poisons - 53MycotoxinsErgot alkaloids consist of three groups: ergotamine, dihydroergotamine, and ergonovine. Affect the nervous system and induce vasoconstriction
Aflatoxins undergo hepatic metabolism to form reactive epoxide intermediate - 54Algal toxinsRepresent the array chemicals derived from cyanobacteria, dinoflagellates, and diatoms
- 55Plant toxins (phytotoxins)Common drugs of abuse (e.g. cocaine, caffeine, nicotine) and components of food (e.g. safrole found in black pepper)
- 56Animal toxinsActively Venomous - injecting poisons through specially adapted strings or mouthparts
Passively Venomous - inadvertent ingestion - 57SolventsCommon classes: Aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, aliphatic alcohols, glycols and glycol ethers, and aromatic hydrocarbons
- 58Drugs of abuseeither have no medicinal function or are taken at dose levels higher than would be required for therapy
- 59Combustion productspolycyclic aromatic hydrocarbons (PAHs) are the most widely studied for aspects of chemical carcinogenesis
- 60CosmeticsLittle risk of systemic poisoning. Most common deleterious effects are allergic reactions and contact dermatitis.