Chapter 4 Questions
Chapter 4 QuestionsChapter 4 Questions_091609.doc4.1.1 Introduction to Toxicology I1.Toxicity refers to the capability of a substance toa)cause systemic harm to a living organism.b)damage an organ in a living organism.c)adversely modify a biochemical system.d)All of the above.2.A toxin is a toxicant that a)is a single, pure chemical instead of mixture.b)is a naturally occurring toxic compound.c)is made synthetically in a laboratory.d)is low molecular weight molecule.3.With regard to toxic dose, the threshold is the level at whicha)permanent damage is done to an organismb)a person starts to feel pain or discomfort c)toxic effects begin to occurd)the level at which some antidote can have an effect4.Acute toxicants are characterized by what features?a)Single, relatively high doseb)Single, relatively low dosec)Long-term exposures of relatively high dosesd)Long-term exposures of relatively low doses5.Chronic toxicants are characterized by what features?a)Single, relatively high doseb)Single, relatively low dosec)Long-term exposures of relatively high dosesd)Long-term exposures of relative low doses6.The process of metabolism explains whya)almost no chemicals have a toxic effect on humans.b)many toxicants can accumulate in the body.c)humans can ingest small amount of toxic substances with little or no effect.d)acute exposures to toxicants are usually less harmful than chronic exposures.7.When molecules are metabolized theya)usually become a less toxic molecules.b)usually becomes a more toxic molecules.c)can become either more toxic or less toxic. d)always become less toxic.8.An LD50 represents the a)amount of a substance that kills 50% of a test populationb)the concentration of a substance that kills 50% of a test populationc)amount of a substance that is known to have killed at least 50 people due to accidental exposure.d)the concentration of a substance that is known to have killed at least 50 people due to accidental exposure.9.The methodology used to determine an LD50 involvesa)slowly increasing the dose until 50% of a test population dies.b)slowly increasing the dose until 5% of a test population dies and them multiplying the dose by ten.c)dosing animals to get a wide range of death rates and interpolating the data to 50%.d)finding the minimum does that kills 100% of a population and then dividing by two.10.What dimension is not used to represent and LC50?a)ppmb)mg/M3c)mg/mLd)g/L11.Poisons are compounds with an LD50 a)≤ 50 mgb)≤ 50 mg/kgc)≥ 50 mgd)≥ 50 mg/kg12.What percentage of compounds can be classified as poisons?a)A small percent.b)about 25%c)about 50%d)almost 80%13.The toxicity values shown in Table 4.1.1.2 cover a range of how many orders of magnitude?a)3b)5c)8d)1114.Which statement is true?a)In general, synthetic compounds are more toxic than naturally-occurring compounds.b)In general, naturally-occurring compounds are more toxic than synthetic compounds.c)There is no relationship between the source of a compound and its toxicity.d)More complex molecules tend to be more toxic.15.Table 4.1.1.3 shows data that allows one to conclude thatthe toxic dose is largely independent of route of exposuremost compounds have remarkably similar toxic dosesLC50 data is often reported with different time exposuresoral LD50 doses are generally lower than dermal (skin) LD50 dosesa)I and IIIb)II and IIIc)I and IId)III and IV16.Table 4.1.1.4 shows thatmost species of animal react about the same to a particular dose (per kg) of a toxicant.LD50 values vary widely according to species.generally, the larger the animal, the lower the LD50.generally, the larger the animal, the higher the LD50.a)I and IIIb)II and IIIc)II and IVd)only II17.To extrapolate animal testing to humans, it has been found thata)using monkeys provides very similar toxicity results as those shown for humansb)there is no animal species that simulates human responses well, but, generally, testing several species lead to reasonably good estimate of human toxicity.c)in general other animals are mostly more sensitive to toxicants than are humans.d)in general other animals are mostly less sensitive to toxicants than are humans.18.Figure 4.1.1.3 shows that the toxic effect of a substance on an individual dependsa)on about ten factorsb)almost entirely on factors that are beyond the control of the individualc)upon factors that are remarkably consistent in a population of individuals.d)mostly on two main factors.19.Figure 4.1.1.1 shows that a)the dose-response curve is linear enough to generally assume that an LD50 is ten times smaller than an LD5.b)most compounds have a threshold nearly equally to zero.c)the dose-response curve is not linear over a wide range of doses.d)generally, higher does ironically lead to smaller responses.20.Synergistic effects explain whythe effect of being exposed to two toxicants is sometime less than the predicted “sum” of the exposures.the effect of being exposed to two toxicants is sometime more than the predicted “sum” of the exposures.there can be variation in the response of a group of people to that same dose of a toxicant.many people have a delayed reaction to a toxicant.a)I and IIIb)II and IIIc)II and IVd)IV21.Antagonistic effects explain whythe effect of being exposed to two toxicants is sometime less than the predicted “sum” of the exposures.the effect of being exposed to two toxicants is sometime more than the predicted “sum” of the exposures.there can be variation in the response of a group of people to that same dose of a toxicant.many people have a delayed reaction to a toxicant.a)I and IIIb)II and IIIc)II and IVd)IV22.Which is true?a)Synthetic compounds are more toxic than naturally-occurring compounds.b)Synthetic compounds are less toxic than naturally-occurring compounds.c)We can draw no general conclusion about the toxicity of a compound based on whether is it synthetic or naturally –occurring.d)If a naturally-occurring compound is also prepared synthetically, it will not have the same toxicity behavior.4.1.2Acute Toxicity1.Acute toxicants are characterized by what features?a)Single, relatively high doseb)Single, relatively low dosec)Long-term exposures of relatively high dosesd)Long-term exposures of relatively low doses2.The most common toxic effect of chemicals is the category of a)allergensb)poisonsc)asphyxiantsd)irritants3.There is often a delay between initial exposure and the response for allergens, but they are considered to be acute toxicants becausea)a high dose is required.b)after sensitization has occurred, the reaction is immediate.c)they involve the immune system.d) All of the above.4.“Simple asphyxiants” a)are chemically unreactive.b)displace oxygen from the air.c)can be lighter or heavier than the average molar mass of air.d)All of the above.5.“Chemical asphyxiants”a)interfere with oxygen uptake through a chemical reaction in the body.b)are actually the same as “simple asphyxiants.”c)are usually not gases.d)cause the blood to coagulate.6.Pulmonary edemaa)is the condition of excess fluid in the lungs.b)can be caused by non-asphyxiant chemicals that react with lung air sacs.c)can occur rapidly or slowly.d)All of the above.7.Teratogens and fetotoxicantsa)have immediate and obvious effects when ingested.b)interfere with the genetic process .c)can have an effect on a fetus, even though the mother may not know this.d)are frequently encountered in introductory chemistry labs.8.Substances that affect the central nervous system are calleda)hepatotoxicantsb)neurotoxinsc)nephrotoxicantsd)teratogens9.What compounds often used as pesticides are also neurotoxins?a)cholinesterasesb)nephrotoxicantsc)organophosphatesd)tetratogens4.1.2Questions/Problems.Using the Ideal Gas Law and Dalton’s Law of Partial Pressures:Assume that you are in a room that measures 15x15x8 feet containing normal air with 21% O2. a) If a fire extinguisher with five pounds of solid CO2 in it is completely discharged, what will the level of % CO2 in the atmosphere? What will be the (reduced) level of O2? Does discharging this extinguisher (to put out a fire) jeopardize the safety of the occupants of the room in terms of decreased O2 concentration? b) Assume that you are using a Dewar flask of liquid nitrogen in order to cool some experimental apparatus. What happens to the O2 concentration in the room, over time as the N2 evaporates, if about three liters of liquid nitrogen is evaporated?All of your previous questions have had answers to choose from. Will this? How will the student answer the questions?4.2.1 Chronic Toxicants1.The likelihood of suffering an adverse, chronic effect while working with chemicals in undergraduate laboratories is a)small, because almost no chronic substances are allowed in labs.b)small, because chronic exposure in academic labs is unlikely.c)moderate, because academic labs take few precautions against exposure to chronic toxins. d)large, but we don’t know how large since all of the effects are delayed.2.Which statement is true?a)Acute toxicity does not predict chronic toxicity.b)We know much more about acute toxicity that we do about chronic toxicity.c)Studies that evaluate chronic toxicity are very expensive.d)All of the above are true.3.Chronic toxicity studiesa)are sometimes not conducted because we don’t know what symptom or effect to measure.b)sometimes occur based on the accidental exposure of a group of people to a chemical.c)are usually more definitive in establishing a cause –effect relationship than acute toxicity studies.d)A and B are true.4.It is known that we ingest small amounts of large numbers of synthetic and naturally-occurring chronically toxic compounds regularlya)and this accounts for the relatively high cancer rate in the United States.b)but since the toxic effects of these substances are not detected it is clear that the body’s defense system can usually handle these chemical assaults.c)but the delay time between ingestion and illness is predicted to be over 80 years so the effects are rarely seen.d)but the effect of these compounds is masked by other illnesses.5.Which factors are the primary causes of chronic disease?Genetics.Lifestyle choices.Age.Chemicals.a)I, II and IV.b)II, III, and IV.c)I, II and III.d)I and IV.6.The element, mercury, a)is much more toxic by ingestion than inhalation.b)produces symptoms as soon as blood level concentrations rise to detectable levels.c)was widely used in laboratories in the 20th century where spills of the liquid Hg occurred and exposed chemists to Hg vapors.d)is the preferred liquid in thermometers because it is so chemically inert.7.The Laboratory Standard (OSHA 29 CFR 1910.1450)a)ignores the issue of chronic toxicity because it is so rare in chemistry labs.b)regulates the specific levels of known chronic toxicants.c)requires that scientists be aware of risks and hazards associated with chronic toxicants.d)requires that the ACGIH determines the TLVs for all chronic toxicants.4.3.1 Carcinogens1.What is the estimated percent of cancers in the U.S. are attributable to chemical exposure in the workplace?a)< 5%b)about 10%c)about 18%d)about 26%2.What percentage of chemicals that is known to cause cancer in humans is regulated by OSHA?a)less than 10% b)about 25%c)about 60%d)100%3.What element and its compounds are regulated by OSHA?a)asbsestosb)arsenicc)cadmiumd)mercury4.For most chemists who work in labs,a)it is probable that they will use and handle some carcinogens, but the likelihood of contracting cancer based on lab activity is very small if appropriate steps are taken to limit exposure.b)it is very unlikely that they will use and handle any carcinogens since carcinogens are so highly regulated.c)it is very likely that they will use and handle carcinogens and some may develop cancer but establishing the causal link to chemical exposure is almost impossible.d)they will avoid using anything carcinogenic since OSHA regulations make it illegal to require a chemist to use carcinogens without signing a release statement.5.What percentage of chemicals tested for carcinogenicity actually turn out to be carcinogens?a)less than 5%b)about 10%c)about 45%d)about 60%6.The percentage of chemicals found to be carcinogens in lab tests is probably higher than the actual percentage of human carcinogens in all known chemicals becausea)these expensive tests are more likely to be run on compounds that are already suspected to be carcinogens.b)very high doses are used and the high-dose-to-low-dose extrapolation probably overestimates the actual chance of the chemical being a carcinogen in humans,c)humans have a better DNA repair mechanism that some animals.d)All of the above.7.Which statement is true?a)Most carcinogens are mutagens.b)All mutagens are harmful.c)About 50-60% of known mutagens are carcinogens.d)Mutagenicity tests are only performed on known carcinogens.8.Which statement is true?a)OSHA regulates about 30 substances as known carcinogens.b)OSHA regulates almost 300 substances as known carcinogens.c)OSHA recommends, but does not require, that special practices be established when handling select carcinogens.d)OSHA has regulates mutagens more strictly than carcinogens. 9.A substance is a “select carcinogen” if ita)is regulated by OSHA as a carcinogen.b)is “known to be a carcinogen” in the Annual Report on Carcinogens published by the NTPc)is listed as Group 1, Group 2A or Group 2B by the IARC and causes statistically significant tumor incidence under specified conditions.d)All of the above.4.3.2 Biotransformation, Bioaccumulation, and Elimination of Toxicants1.A xenobiotic substance is one whicha)has an unusually high toxicity.b)is usually eliminated before it can metabolize.c)does not normally occur in the body.d)was synthesized by Zena the Warrior Princess2.The purpose of biotransformation of a xenobiotic substance in the body is to change it into aa)naturally-occurring, less toxic substance.b)more hydrophilic form that can be more easily eliminated.c)more hydrophobic form that can be more easily eliminated.d)more hydrophobic form that is less toxic.3.In Phase 1 Biotransformation, enzymes are used to effect which chemical reaction?a)Hydrolysis.b)Reduction.c)Oxidation.d)All of the above.4.In Phase 1 Biotransformation, epoxide function groups becomea)alcohols.b)carboxylic acids.c)phenols.d)ethers.5.In Phase 1 Biotransformation, chemical toxicants a)are always converted into less toxic substances.b)are always converted into more toxic substance.c)can be converted into substances that can be either more or less toxic.d)None of the above.6.In Phase 2 Biotransformation, what class of molecules is used to effect conjugation?a)Amino acids.b)Carboxylic acids.c)Alcohols.d)Enzymes.7.In Phase 2 Biotransformation, xenobiotic substances are converted to a)more hydrophobic forms that more easily react with enzymes.b)more hydrophilic forms.c)smaller molecules that are more hydrophilic.d)larger molecules that are more hydrophobic.8.In order for bioaccumulation to occur, a chemical toxicant must bea)absorbed faster than it is eliminated. b)absorbed slower than it is eliminated. c)converted to a more hydrophilic form.d)converted to a more hydrophobic form.9.The half-life for the elimination of bioaccumulated substances is a)on the order of hours.b)on the order of days.c)on the order of years.d)All of the above.4.3.3 Biological Hazards and Biosafety1.Virusesa)have a central core of DNA or RNA.b)have a protective protein coating.c)are not alive.d)All of the above.2.Bacteriaa)are alive.b)are all easily dyed.c)cannot be killed with antibiotics.d)contain no DNA.3.Which poses the largest risk of infection upon exposure?a)Hepatitus viruses.b)HIVc)Hepatitus and HIV have the same risk.d)This depends upon the individual.4.When comparing infectious agents with chemical toxicants a)for chemical toxicants, “the dose makes the poison” while for infection agents, the dose is largely irrelevant since even a tiny exposure can multiply in the body.b)for both substances, “the dose makes the poison.”c)using PPE for infectious agents is much more important since exposure usually leads to fatality.d)different kinds of PPE are used for infectious agents as compared to chemical toxicants.5.Which practice is generally not needed when using infectious agents?a)Using gloves.b)Avoiding mouth pipetting.c)Using chemical splash goggles.d)None of the above.6.Which two practices are more important to consider when handling infectious agents as compared to handling chemical toxicants.a)Washing hands and disposing of sharps.b)Washing hands and disinfecting work areas.c)Disposing of sharps and disinfecting work areas.d)Disposing of sharps and using gloves.7.How many Biosafety Levels are established by the CDC and NIH?a)Twob)Threec)Fourd)Five ................
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