Toxicology and Disease
What is the precautionary principle? A product should not be introduced under what conditions? What is an example?
"An ounce of prevention is worth a pound of cure" - old expression at the heart of the precautionary principle • Precautionary principle = when a new technology or chemical product is suspected of threatening health or the environment, we should undertake precautionary measures, even if we are unsure of the danger • No product should be introduced, or action taken, when the science is inconclusive, the product has not been tested, or unknown risks may exist • Rachel Carson advocated this principle with respect to pesticides • Many pesticides had not been adequately tested for their effects, so they should not have been introduced to the environment
What is responsible for 15% of the deaths of women of reproductive age?
Pregnancy complications account for 15% of deaths of women of reproductive age
In what ways does lead enter our body? What are the effects of lead on the human body?
• Ingesting food or water from ceramic tableware produced with lead-containing glazes • Ingested food or water contaminated by lead pipes, soil or mine waste containing lead • Ingesting lead-based paint (especially children); effects • Birth defects • Nervous system damage • Brain damage • Learning disabilities • Paralysis • ADHD • Similar to mercury poisoning
What are the sources of lead in our environment?
• Lead paint • Water pipes • Lead glaze on ceramics • Gasoline additives • Cosmetics • Batteries • Mine waste
How can your exposure to lead be minimized?
• Remove lead paint • Remove lead pipes • Treat water supplies to remove lead • Remove, cap, or contain mine waste or soil with high levels of lead
What percentage of people infected by the cholera bacterium develop the severe form? What are the symptoms of the severe form?
5-10% of infected persons will contract a severe form, whose symptoms include: • Profuse, watery diarrhea • Vomiting • Leg cramps • Rapid loss of body fluids leads to dehydration and shock • Without treatment, death can occur within hours
What is the LD50 of water? The lower the LD50, the ___________ toxic the substance.
6 liters; the more toxic the substance,
What form does the sporozoite change into upon entering a human, and where does this happen?
• Upon biting, the sporozoite enters the human and changes forms into a merozoite in liver cells
In what ways can you minimize your exposure to BPA?
• Use BPA-free plastic water bottles • Use glass storage containers for food storage/microwave use • Don't drink bottled water
What is an example of an oxygen uptake disrupter, and what process causes it to be given off? What does it do to prevent the transport of oxygen?
• Ex - carbon monoxide • Given off during burning of fossil fuels • Binds to hemoglobin, preventing it from carrying oxygen
What has reduced the life expectancy by more than 20 years in some countries? What are the names of these countries, and on what continent are all of them located?
• HIV has reduced life expectancy by more than 20 years in the following African countries: • Botswana • Lesotho • Swaziland • Zimbabwe
What does HIV stand for? Where does it rank among killer diseases? What is its rank in Africa? What specific cells are infected by HIV?
HIV = human immunodeficiency virus • 2nd biggest viral killer after influenza, and leading cause of adult death in Africa • HIV infects helper T cells, the cells that activate and mount your immune response
What is the classic symptom of malaria? When does the fever occur? Malaria has killed more people over history than what other events?
Classic symptom of malaria involves cycles of fever followed by chills • Each fever/chill cycle lasts 2- 3 days • Fever occurs when merozoites burst out of red blood cells Over the course of history, malaria has killed more people than all the wars ever fought
What are 4 reasons why TB has reemerged?
Why has TB reemerged? • Increased human population density makes human-human transmission more likely • Evolution of antibiotic resistant strains of TB makes it more difficult to kill • Multidrug-resistant TB is a new, deadly strain that is impossible to kill (victim must be permanently isolated from society) • 440,000 new cases each year • Increase air travel has increased person-person contact • Increase in AIDS infection rate has increased TB prevalence • AIDS weakens immune system and makes a person more vulnerable to the infection • People with AIDS are 30-50 times more likely to develop active TB
What chemicals are toxic to humans? What is the old saying with respect to a dose? When can water be toxic, and what can it do to your cells?
• All chemicals! • Old saying: "The dose makes the poison" • Water can be toxic, if a large enough dose is ingested
AIDS makes one susceptible to what type of infections and cancers? What are two examples of these types of infections/diseases?
• With AIDS, one is vulnerable to opportunistic infections or cancers, which are normally killed by your immune system - examples: • Kaposi's sarcoma - tumor due to a virus • Thrush - caused by a fungus
What is toxicology? What is toxicity?
•toxicology- The study of the adverse effects of chemicals on living organisms •toxicity- A measure of the harmfulness of a substance - its ability to cause injury, illness, or death to a living organism
What causes BPA to leach quickly from plastic products? Is this the only way BPA can leach into your food and water?
• BPA leaches quickly into water or food when the plastic is heated, microwaved, or exposed to acidic liquids • Now known that BPA is released into food/drink even when the bottle is not heated
What are the 3 main reasons for the difference in life expectancy and infant mortality between HDCs and LDCs?
• Healthcare • Vaccinations • Level of nutrition to support growth and development
What is the dilution paradigm? What does it assume? How was this shown to be false with respect to DDT?
"Dilution is the solution to pollution" • Called the dilution paradigm, and assumes that the environment will dilute toxins down to safe concentrations • Shown to be false many times • Ex - DDT, and other chemicals, undergo biological magnification, so even though they are extremely dilute in the water, their concentration increases as you move up the food chain
What are synthetic organic chemicals? What are 3 of their characteristics that make them particularly harmful? What are some examples of synthetic chemicals?
3 characteristics of synthetic (man-made), organic chemicals make them particularly harmful: • Persistence • Bioaccumulation • Biological magnification • Examples of these synthetic chemicals include: • DDT, Aldrin, and dieldrin (synthetic pesticides) • PCBs • Dioxins
What organisms convert elemental or ionic mercury into a more toxic form? What is the name of this most toxic form of mercury, and what is its chemical formula?
Anaerobic bacteria living in the sediments of lakes and the ocean convert elemental or ionic mercury into methyl mercury • The sulfide produced by anaerobic bacteria combines with ionic mercury (Hg2+), forming HgS, which easily crosses the membrane into the bacteria • Bacteria then methylate the mercury, releasing CH3Hg+(methyl mercury), the most toxic form of mercury
What hormone does BPA mimic? How? What are the effects of BPA exposure?
Its shape allows it to bind to estrogen receptors on your cells, causing: • Brain damage • Early puberty • Decreased sperm quality • Impotence in males • Increased incidence of certain cancers • Some cancers, such as some forms of breast cancer, are estrogendependent
What are the effects of mercury on the human body? What body system is mainly affected by mercury?
• Birth defects • Nervous system damage • Brain damage • Learning disabilities • Mental retardation • Paralysis
How is the acute toxicity of a chemical determined? What does LD50 stand for, and how is it defined?
• LD50 = lethal dose-50% = the dose lethal to 50% of a population of test animals
What is a carcinogen? What are two examples, and in what product(s) is each found?
Types of chemical hazards: • Carcinogens = chemicals or radiation that cause or promote cancer • Ex - benzene - found in: • Gasoline • Ex - formaldehyde - found in: • Plywood • Cigarette smoke (anything burned, actually)
What are 2 reasons why viruses are so dangerous? What virus is the biggest killer among viruses? What was the name of the 1918-19 virulent flu strain that killed 850,000 in the U.S?
What makes viruses dangerous? • Viruses are not susceptible to antibiotics • Viruses evolve quickly, so new strains are always appearing • The influenza (flu) virus is the biggest killer among viruses • Every year, one or more new strains appear • 5-10% of the U.S. population contract the flu each year, and 36,000 die each year • During 1918-19 a virulent strain called the Spanish flu struck • 850,000 in U.S. were killed (1% of population)
What is persistence? Why are synthetic chemicals persistent? Why is DDT considered persistent, even though it degrades naturally on its own?
Persistence = a characteristic of certain chemicals that are extremely stable and may take many years to break down into simpler forms through natural processes. persistant bc: • They have a novel (not found in nature) chemical structures • Decomposers, as well as other organisms, have not yet evolved ways to degrade these chemicals • No degradation = persistence • Ex - DDT is a synthetic pesticide with a novel structure that can't be broken down by living organisms • It degrades naturally on its own, but it takes a long time
What were the life expectancies for each sex in the U.S. in 1900? What about today?
• 1900 = 51 for women, 48 for men • Today = 80 for women, 75 for men
Merozoites infect which cells in a human? What happens when they get into the cell? What happens to the cell at the end of this process?
• The merozoites infect red blood cells, reproduce, destroy the cell, then go and infect new red blood cells
What does a dose-response curve show? How is it constructed?
A dose-response curve shows the effect of different doses on a population of test organisms • Scientists first test the effects of high doses, then work their way down to a threshold level • Some dose-response curves are linear, indicating a steady increase in physical effects as the concentration of the toxin increases • The curve on the right is not linear - it shows that the toxicity rapidly escalates as concentration increases
What are a significant fraction of premature deaths in the U.S. now caused by? What are some examples of these choices?
A significant fraction of premature deaths in the U.S. are now caused by lifestyle choices: • Smoking • Poor diet • Obesity • Lack of exercise
What does 'BPA' stand for? What is the compound used for? In what products is it found?
BPA = bisphenol A • Used as a hardening agent in certain plastics (especially shatter proof polycarbonate), which is found in: • Baby bottles • Sipping cups • Bottled water bottles • Sports drink bottles • Food storage containers • Plastic resins that line food and soda cans • Receipts from thermal printers
What is bioaccumulation? Why does DDT bioaccumulate? How does the solubility of DDT affect its accumulation in living organisms? Why might DDT be a cause of breast cancer? Why can DDT be passed to a baby during breast feeding?
Bioaccumulation = the buildup of a persistent toxic substance in an organism's body, often in fatty tissues • Ex - DDT • DDT is not broken down in the body • It is not excreted by the body because it is not water soluble • Because it is not water soluble, it accumulates faster than it is lost from the body • It is fat soluble, so it accumulates within the fatty tissues of the body, often to dangerously high levels • Probably one cause of breast cancer, as the breast contains a lot of fatty tissue • DDT is soluble in fatty milk, so it is passed to the baby during breast feeding
What are some reasons why young children are more susceptible to toxins? What did the study of 4-year old Native American girls show?
Biological magnification = the increased concentration of toxic chemicals in the tissues of organisms that are at higher levels in the food chain • Ex - DDT • Sprayed in a Long Island salt marsh to control mosquitoes • Concentration of DDT in water was only 0.00005 ppm (parts per million) • Concentration in ring-billed gulls was 75 ppm • Caused thinning and cracking of egg shells, resulting in death of chicks • Each organism in a food chain eats many individuals in the level below it, so the toxin gradually accumulates as you move up the food chain • So persistent chemicals have their greatest effect on the highest levels of the food chain
What is biological magnification? What is a famous example of biological magnification? What effect did this have on ring-billed gulls? Why does biological magnification occur?
Biological magnification = the increased concentration of toxic chemicals in the tissues of organisms that are at higher levels in the food chain • Ex - DDT • Sprayed in a Long Island salt marsh to control mosquitoes • Concentration of DDT in water was only 0.00005 ppm (parts per million) • Concentration in ring-billed gulls was 75 ppm • Caused thinning and cracking of egg shells, resulting in death of chicks • Each organism in a food chain eats many individuals in the level below it, so the toxin gradually accumulates as you move up the food chain • So persistent chemicals have their greatest effect on the highest levels of the food chain
Chisso Corporation in Japan released large quantities of what substance into a nearby bay? What was the name of the bay? Minamata disease was first noticed in what animals?
Chisso Corporation in Japan released large quantities of industrial wastewater contaminated with high levels of methyl mercury into Minamata Bay, Japan, from 1951-1968 • Minamata disease was 1st noticed in cats, which had trouble walking, went into convulsions, then died
What is cost-benefit analysis? We would always like to reduce the potential risk of some chemical to what value? What are 2 reasons why this may not be possible?
Cost-benefit analysis = a comparison of the estimated cost of some regulation to reduce risk to the potential benefits associated with that risk reduction • We would always like to reduce the potential risk of some chemical to zero • Cost of this reduced risk may be too much • Technology may not exist to reduce the risk to zero • Chemical companies always say that the cost of reducing risk is too great, and that increased prices would "hurt the consumer"
What is the definition of dose? What are 3 ways in which a chemical may enter the body?
Dose = the amount of a chemical that enters the body of an exposed organism • May be ingested, inhaled, or absorbed through the skin
What agency establishes maximum risk standards for chemical exposure? 1 mg/L is equivalent to 1 part per _______________. 0.001 mg/L is equivalent to 1 part per _______________.
EPA (Environmental Protection Agency) 1 mg/L = 1 part per million (ppm), 0.001 mg/L = 1 part per billion (ppb)
What are 2 ways to determine whether a chemical causes cancer? How does the toxicology method work? What are 2 reasons why it might be difficult to extrapolate the results of a toxicology study to humans?
Epidemiology and toxicology • Toxicology = dose rats with varying levels of chemicals to see if they develop cancer or other abnormalities • Sometimes difficult to extrapolate (extend) the results to humans • Humans may process chemicals differently than rats • Human and rat life expectancies are different
What recently emergent virus is also spread by mosquitoes? How do mosquitoes become infected? What severe symptoms are developed by less than 1% of people infected? Control involves the same measures used for what other disease?
Facts about West Nile virus: • Emergent virus • Spread by infected mosquitoes • Mosquitoes become infected by feeding on infected birds • Is not carried from an infected human to a non-infected human • 70-80% of infected people do not develop symptoms • 20% of infected people get fever, headache, and body aches • Less than 1% of infected develop severe symptoms, including encephalitis (brain inflammation) or meningitis (inflammation of the membranes surrounding the brain) 10% of these will die • No treatment or vaccine exists • Has been reported in all 48 lower states • Same control measures as for malaria
What are 3 reasons why genetic resistance of bacteria to antibiotics is increasing? What does MRSA stand for? What disorders can MRSA cause?
Genetic resistance of bacteria to antibiotics is increasing due to: • Overuse of antibiotics • Includes antibiotics added to feed of livestock • Use of antibacterial soap • Overuse of pesticides • Pesticide-resistant insects harbor bacteria • MRSA = methicillin-resistant Staphylococcus aureus • Resistant to most antibiotics • Can cause flesh-eating wounds,
What is an example of an immune system disrupter, and in what products is it found? What is an example of a nervous system disrupter, and in what products is it found?
Immune system disrupters • Ex - arsenic • Found in pesticides and preserved lumber Nervous system disrupters • Ex - PCBs (polychlorinated biphenyls) • Found as an insulator in electrical equipment and lubricants
What is an infectious disease? What is the difference between a transmissible disease and a nontransmissible disease? What are a couple of examples of each?
Infectious disease = a disease caused by a pathogen such as a bacterium, virus, or parasite invading the body and multiplying in its cells and tissues • Transmissible disease • An infectious disease that can be transmitted from one person to another • Also called contagious or communicable disease • Ex - bacterial diseases such as tuberculosis and gonorrhea and viral diseases like the cold, flu, and AIDS • Nontransmissible disease • Caused by something other than a living organism, and does not spread from one person to another • Ex - cardiovascular disease, most cancers, asthma, diabetes
What environmental disaster occurred at Love Canal in New York?
Love Canal in New York was a partially dug canal that was turned into a municipal and industrial chemical dumpsite • It was covered with earth by a chemical company, then sold to the city • A housing development was later built on the land • High levels of dioxin, benzene and other chemicals caused a huge increase in cancer and birth defects
What is malaria caused by? How is the malaria parasite transmitted? Where does the sporozoite stage of malaria reside in the mosquito?
Malaria is caused by a parasite in the protozoan genus Plasmodium that is spread by the bite of the female Anopheles mosquito • The sporozoite stage of the parasite resides in the salivary gland of the mosquito
How is 1/3 of all mercury released into the environment? Where does the other 2/3 come from? What is the primary source? What are the secondary sources?
Mercury and its compounds are all toxic • How is it released into the environment? • 1/3 of it is released naturally into the air from rocks, soil, volcanoes, and vaporization from the ocean • 2/3 comes from human activities • Prime source is from burning coal in coal-fired power plants • Secondary sources include: - Thermometers - Fluorescent light bulbs - Batteries
What two processes cause methyl mercury to increase in concentration as it passes up the food chain? What fish species carry a high mercury load?
Methyl mercury, through biological magnification and bioaccumulation, begins to pass up the food chain • Top level predatory fish, such as tuna, swordfish, or striped bass, become loaded with methyl mercury through biological magnification
Name and define the 3 ways in which mixtures of chemicals may interact with one another.
Mixtures of chemicals (such as cigarette smoke) can interact in a variety of ways: • Additivity = the effect of 2 or more chemicals together is equal to the sum of their individual effects • Synergy = the effect of 2 or more chemicals together is greater than the sum of their individual effects • Ex - exposure to 2 different pesticides or herbicides at once may cause a greater negative effect than expected based on their individual toxicities • Antagonistic = the effects of 2 or more chemicals together is less than the sum of their individual effects
What is a mutagen? What is an example, and in what product(s) is it found? Mutations in certain genes can cause what disease to develop?
Mutagens = chemicals or radiation that increase the frequency of mutations (changes) in DNA • Ex - nitrites, preservatives found in: • Processed foods, such as lunchmeat • Mutations to certain genes cause cancer to develop
What is contributing to the rise in cancer and heart disease? What cancer is the most common cause of death from cancer?
Population aging is contributing to the rise in cancer and heart disease • Lung cancer is the most common cause of death from cancer in the world
What is a reemerging disease? What are 3 examples?
Remerging disease = existed in the past, and recently increasing in incidence - examples: • Tuberculosis • Yellow fever • Malaria
With respect to a dosage, what is the definition of the response? Name and define the two types of responses, and give an example of each.
Response = the type and amount of health damage resulting from exposure to a chemical • Two types of responses: Acute = rapid or immediate • Ex - fast breathing or dizziness Chronic = permanent or long-lasting • Ex - liver damage
What is risk? What is risk management? What is risk assessment?
Risk = the probability that a particular adverse effect will result from some exposure or condition • Risk management = the process of identifying, assessing, and reducing risks • Risk assessment = the use of statistical methods to quantify the risks of a particular action so that those risks can be compared and contrasted with other risks
What is a teratogen? What are 2 examples? Who was thalidomide sold to, and why?
Teratogens = chemicals or radiation that cause birth defects in a fetus or embryo • Ex - alcohol • Ex - thalidomide • Sold to alleviate morning sickness, but caused birth defects (phocomelia = short limbs)
HIV is what type of virus? Why does this make it harder to fight? Why does the RNA genome of HIV make it problematic for humans? After insertion, what happens to the HIV DNA? Why is this problematic for humans?
Why is HIV hard to fight? • It is a retrovirus, so it has RNA as its genetic material • It uses an enzyme called reverse transcriptase to produce DNA from its RNA, which inserts itself into our DNA • This mechanism is foreign to us, making it harder to fight • RNA goes through very rapid mutation • We normally repair mutations in DNA, but we can't do this for RNA • Our immune system cannot keep up with the mutational changes to its surface proteins • After inserted, the HIV DNA lies latent, often for many years • While latent, the cell is dividing, producing new helper T cells that are infected • Several years later, an activation event will occur, turning all of the infected cells into virus factories at virtually the same time • This overwhelms the immune system
What are the 2 indicators of human health in a given country? What is life expectancy? What country has the highest life expectancy? What is its value? What country has the lowest life expectancy? What is its value?
life expectancy and infant mortality; • Life expectancy • How long people are expected to live - examples: • Japan (an HDC) • Life expectancy = 86 for women and 79 for a man • Sierra Leone (an LDC) • Life expectancy = 46 for both sexes (only 38 in 1990)
What can an HIV infection develop into? What does AIDS stand for? What is the normal helper T cell count, and how low must it get to be called AIDS?
• AIDS - acquired immunodeficiency syndrome • Normal helper T cell count is 500- 1600 cells/mm3 • If helper T cell count falls below 200 cells/mm3 , the disease has progressed to AIDS
How many children under the age of 5 die each year? What would save most of these kids? What is the cause of death for 30% of the deaths in children under 5?
• About 10 million children under the age of 5 die each year • Most could be saved with inexpensive treatments • Undernutrition is the cause of death for 30% of the deaths in children under 5
What are 7 factors that determine the harm caused by exposure to a chemical?
• Amount of exposure (dose) • Frequency of exposure • Age of person exposed (Young children are more susceptible) • Effectiveness of the body's detoxification systems • Genetic makeup (Some people are genetically susceptible, and are very sensitive to a chemical, Other are genetically insensitive to the chemical) • Solubility of the chemical • Persistence of the chemical (How resistant is the chemical to breakdown by the body?)
What are the 3 biggest health problems in LDCs? What is the worldwide life expectancy? What 4 countries have life expectancies of 49 years or less? On what continent are all of these countries located?
• Biggest problems: • Malnutrition • Unsafe water • Poor sanitation • Urban overcrowding (rural poverty causes people to move into cities) • Life expectancy: • Worldwide = 70 years • 4 countries have life expectancies of 49 years or less: • Sierra Leone • Botswana • Lesotho • Swaziland
What does the boomerang paradigm state? What is ecotoxicology? How is it different from plain old toxicology?
• Boomerang paradigm = what you throw away can came back and hurt you • Ecotoxicology = the study of contaminants in the biosphere, including their harmful effects on ecosystems • Toxicology is human oriented • Ecotoxicology is human oriented, in the sense that humans produce the toxins that adversely affect the environment • Ex - humans synthesized DDT, which adversely affected birds
What is the most toxic chemical known? What is it commonly known as? What bacterium produces it? How can you get botulism?
• Botulinum toxin, commonly known as Botox • Botox is the most potent neurotoxin known, and is produced by the bacterium Clostridium botulinum • Causes botulism, which you can get from improperly canned food
What is the leading cause of death worldwide? What is the leading cause of adult death in Africa?
• Cardiovascular disease is the leading cause of death • HIV/AIDS is the leading cause of adult death in Africa
What is cholera caused by? What organ does it infect? An acute form of what disorder is caused by this disease?
• Cholera is caused by the bacterium Vibrio cholera • This bacterium infects the intestine, causing acute diarrhea
How does one get cholera? What is usually the source of contamination during an epidemic? Where can cholera spread rapidly?
• Drinking water or eating food contaminated with the cholera bacterium • In an epidemic, the source of contamination is usually the feces of an infected person that contaminates water/food • Cholera can spread rapidly in areas with inadequate treatment of sewage and drinking water • Unlikely to spread directly from one person to another
Which two toxic forms are mercury can we eliminate, and why? Why can't we break down mercury?
• Elemental mercury and ionic mercury are harmful, but their water solubility allows us to more easily eliminate them • We have no mechanism for breaking down mercury (can't break down elements)
What is an emerging disease? Give 4 examples, and state which animal each made the jump from in order to infect humans.
• Emerging diseases = infectious diseases not previously found in humans - usually jump to humans from animal host -examples: • AIDS = previously found in chimps, and jumped to humans upon exposure to contaminated blood when butchering or eating chimps • Lyme disease = caused by a bacteria that normally infected deer and mice (vector is a tick) making the jump to humans • West Nile Virus = previously found in horses, but make jump to humans (mosquito is the vector) • Ebola virus = previously found in bats, but made jump to primates, including humans
What are 4 reasons why the Spanish flu was so bad?
• End of WWI, so hardships made people vulnerable: Hunger, Lack of medicines •Time of unprecedented international travel (Troop movements) • As lethal to young healthy people as to old or very young people (Rare for flu) • No flu vaccine • Now we can vaccinate, but we must predict which strains will become common
What is threshold level? What is the LD50 in terms of a dose-response study? What does ED50 stand for? How is it defined?
• Threshold level = the maximum dose at which there is no measurable effect (or the minimum dose with a measurable effect) • LD50 = dosage at which 50% of the population dies • ED50 = effective dose-50% - The dosage that causes 50% of the population to exhibit whatever response is under study - Ex - dosage that causes hair loss in 50% of exposed individuals
What is an epidemic? What is a pandemic? What was the common name given to the H1N1 virus? Why was it called that?
• Epidemic = the rapid spread of infectious disease to a large number of people in a given population within a short period of time • Pandemic = an epidemic that has spread through human populations across a large region or worldwide - examples: • Spanish flu • Swine flu (H1N1) -Originated in Mexico in April 2009 -By May it had spread to several dozen countries, and by June it was considered pandemic -Called swine flu because it originated in humans, but made jump to pigs -Paul Ehrlich warned that international travel can rapidly spread disease in The Population Bomb
What are the reasons why a disease might emerge or reemerge?
• Evolution of disease so it transitions to human host • Evolution of antibiotic resistance • Urbanization and overcrowding • Aging population - old more susceptible to diseases • Pollution and environmental degradation • Global warming • Growth in international travel • Poverty and social inequality (decrease in medical care)
What is an example of an endocrine system disrupter, and in what products is it found? This chemical mimics the effects of what hormone, and what is the result?
• Ex - BPA • Found in plastics, such as baby bottles • Mimics effects of estrogen, causing feminization
What are 5 reasons why malaria has increased since the 1970s? How has global warming had an effect? How has deforestation had an effect?
• Global warming - Mosquitoes lay eggs, and the larvae do best in, warm, standing water - Increased temperatures also increase the transmission rate of mosquitoes (more active when it's warm) - Melting ice produces more mosquito habitat/standing water • Decreased populations of mosquito predators, such as bats and birds • Increased population density allows for increased transmission opportunities • Emergence of pesticide-resistant mosquitoes and antimalarial drugresistant parasites • Deforestation of tropical forests • More people live there • Sunlit pools of warm water are created - perfect breeding ground for mosquitoes
How is HIV transmitted? What body fluids can transmit HIV? What are 2 behaviors that can put one at risk for HIV? How can it be transmitted from mother to baby?
• HIV is transmitted by body fluid contact with a mucus membrane or the bloodstream of a non-infected person • Only certain body fluids from an HIV-infected person can transmit HIV: • Blood • Semen • Vaginal fluids • Breast milk Risky behaviors: • Having sex (especially unprotected) • Sharing needles • May also be transmitted by an infected mother to her fetus or breast-feeding baby, or by exposure to infected blood
Where did the expression "mad as a hatter" come from? Why were hat makers exhibiting these symptoms?
• Hat makers in the 1800s trembled, sputtered, and acted strangely, hence the saying "Mad as a hatter" • Mercury was used to felt the furs that hats were made of, so hat makers were being exposed to large doses of mercury on a daily basis
What are the 4 steps to risk assessment?
• Hazard identification • Does exposure to substance cause increased likelihood of adverse health effects, such as cancer or birth defects? • Dose-response assessment- What is the relationship between the dose and the seriousness of adverse health effect? •Exposure assessment- How much, how often, and how long are humans exposed to the substance • Risk characterization- What is the probability of an individual having an adverse health effect?
What has reduced many diseases in HDCs? What are 3 examples of diseases that have been reduced in this way? What childhood diseases have effectively been conquered in HDCs?
• Health is generally good •Improved sanitation has reduced many diseases, such as: • Typhoid • Cholera • Dysentery • Many childhood diseases have effectively been conquered • Polio • Measles • Mumps
What are 4 ways to fight/prevent malaria? What are 2 ways to reduce mosquito populations?
• How do we fight/prevent malaria? • Reduce mosquito populations: -Use biological mosquito controls, such as fish like the mosquitofish, that feeds on mosquito larvae, as well as frogs, bats, and birds - Spray mosquito habitat with pesticides - DDT was sprayed on the East coast of the U.S. to kill mosquitoes - The WHO supports use of low concentrations of DDT for spraying the insides of homes twice a year • Take prophylactic antimalarial drugs • Sleep under insecticide treated bed nets • Drain swamps/ponds that serve as mosquito habitat
What is another reason why toxicology studies may not be applicable to humans in real life? What is epidemiology? How is it done?
• Humans are also exposed to mixtures of chemicals that may amplify or offset each other Epidemiology = the study of the effects of toxic chemicals and diseases on human populations • Look at historical exposure of groups of humans • See if exposed group has an increased cancer rate over the unexposed group
How is cholera treated? What can be taken to shorten the course of the disease?
• Immediate replacement of the fluid and salts lost through diarrhea • Drink an oral rehydration solution, a prepackaged mixture of sugar and salts that is mixed with water and drunk in large amounts • Antibiotics shorten the course and diminish the severity, but are not as important as rehydration
What are 4 reasons why cholera has reemerged?
• Increased human population density, without increased sanitation - causes increased transmission of the pathogen • Lack of access to pathogenfree water • Global warming is causing suitable conditions for bacterial outbreaks • Increase in frequency of natural disasters, such as tsunamis and floods (Fouls the water supply flooding causes sewage to enter the water supply)
What is infant mortality? What are the infant mortalities of Japan and Sierra Leone? What country has the highest infant mortality, and what is its value?
• Infant mortality • How many infants die before the age of one • Japan • Infant mortality is 2.6 per 1000 live births • Sierra Leone • Infant mortality = 72 per 1000 (highest is Afghanistan at 115 per 1000)
What happens to mercury once it is expelled into the atmosphere? What are two ways in which it can return to Earth's surface?
• Major anthropogenic (human) source is burning of coal in coalfired power plants • Once expelled into the atmosphere, wind distributes the mercury throughout the atmosphere • Mercury falls back onto Earth's surface or into surface water either as dry particles, or rainfall can wash it out of the atmosphere and back onto the surface or into the surface water
Why does methyl mercury bioaccumulate? What is the problem with consuming larger, older fish? What are two ways in which we take in the other forms of mercury?
• Methyl mercury is not very soluble, and begins to bioaccumulate in predatory fish (they take it in faster than they can eliminate it) • Humans eating tuna and other fish are then exposed to a large dose of methyl mercury (also, bigger fish are older and have had more time to accumulate it) • Humans take in other forms of mercury by ingesting food or water contaminated by mine wastes (mercury is used to mine gold) and the particulate or elemental form being deposited from the atmosphere
What are the human symptoms of Minamata disease? Which group of people were primarily being affected, and why?
• Numbness in hands and feet • Stumbled when walking • Had trouble grasping objects, seeing, hearing, and swallowing • Finally severe convulsions, paralysis, coma, and death • Fishermen and their families were eating fish with extremely high concentrations of methyl mercury • Some people had concentrations in their hair of as high as 705 ppm (4 ppm was normal in the rest of Japan)
What are 4 factors that can influence an individual's risk due to chemical exposure?
• Occupation • Where they live • Age • Lifestyle
List, in order, the 4 biggest killer diseases. Where do most of the deaths from these diseases occur?
• Pneumonia (bacteria) and flu (virus) -3.2 million deaths • HIV/AIDS (virus) - 1.7 million deaths • Diarrheal diseases (bacteria or virus) - 1.6 million deaths • Tuberculosis (bacteria) -1.4 million deaths • Hepatitis B (virus) - 1 million deaths • Malaria (protozoan) - 655,000 deaths • Measles (virus) - 139,000 deaths Most of these deaths are poor people in LDCs
What is the cosmetic use of botox? What is the LD50 of botox? How big would the dose have to be, in grams, to have a 50% chance of killing an 80 kg person (express your answer in scientific notation)? What makes botox relatively safe for cosmetic use?
• Prevents wrinkles by paralyzing facial muscles • LD50 = 1 ng/kg • 1 nanogram per kilogram = 60 nanograms for a 132 lb person • 60 ng = 0.00006 mg, and incredibly low dose to kill a person • How is botox relatively safe for cosmetic use? • The dose makes the poison, so the dose administered is very low, and is given infrequently
How is risk calculated? How is risk normally reported? What is the risk of a smoker dying from cancer in the U.S. if 80,000 Americans died last year from cancer caused by smoking, out of a total of 320 million Americans?
• Probability that some negative effect or event will occur times the consequences (death, injury, economic losses) if it does occur • Risk is normally reported as a fraction, ranging from 0 (certain not to occur) to 1 (certain to occur) • Ex - 160,000 Americans who smoked last year died of cancer, out of 320 million Americans • Risk = 160,000/320,000,000 = 0.0005 = 5 x 10-4
What are 2 problems with the epidemiology approach? What is the best way to determine if a given chemical causes cancer?
• Problems: • Difficult to reconstruct historical doses • Exposure to other chemicals might not be recorded • Best to combine
What does SARS stand for? SARS is a serious form of what disorder? Where did most deaths occur? What is the virus transmitted by? How was it controlled?
• SARS = severe acute respiratory syndrome • Emergent viral disease • Serious form of pneumonia, causing severe breathing difficulty and sometimes death • First reported in Asia in 2003 • Caused 774 deaths, spreading to 37 countries in a couple of months (most deaths were in Hong Kong) • Transmitted by Chinese horseshoe bats, but found in palm civets in Hong Kong markets - Virus had jumped from bats to civets and humans - Controlled by destroying infected animals, and keeping animals away from humans - Facial masks prevented human to human spread through coughs and sneezes - Was eradicated by early 2004
Some merozoites develop into what type of cell? What happens next to this cell type? What form does this cell type eventually develop into, completing the life cycle?
• Some merozoites develop into gametocytes in red blood cells, which are then taken in by a mosquito feeding on the blood • Gametocytes form gametes, which fertilize, forming oocysts in the mosquito gut • Oocysts develop and form sporozoites, which travel to the salivary gland of the mosquito, completing the life cycle
How is TB spread? TB typically attacks what organs? What is TB named after?
• Spread by respiratory droplets (coughing, sneezing, mucus) • Only people with active TB are contagious, but they are very contagious • A single sneeze may release 40,000 aerosol droplets, and each may transmit the disease • Inhalation of fewer than 10 bacteria may cause the infection • TB typically attacks the lungs • Symptoms include chronic cough with bloodtinged sputum, fever, night sweats, and weight loss (why called consumption) Tuberculosis • TB named after tubercles that form in the lungs • Body walls off infection that it can't kill off easily • Tissue necrosis (death) occurs in walled off area
What are some ways in which human exposure to mercury can be minimized?
• Substitute safe alternatives for mercury in industry • Reduce coal burning (use other energy sources, such as natural gas or renewable energy sources, which do not contain mercury) • Use technology to remove mercury from coal, or burn higher-quality, cleaner coal with a lower mercury content • Restrict fishing for species of fish and shellfish known to have high concentrations of mercury • Don't eat these fish! • Remove, cap, or contain mine waste with high levels of mercury
What disease is sometimes called consumption or the white plague? What type of organism causes it? What fraction of the world's people are infected? Most of these have what form of TB? What percentage of these will develop active TB?
• The incidence of tuberculosis (TB), also called consumption, or the white plague, has been increasing since 1990 • TB is caused by a bacterium that is extremely contagious • Worldwide, 1/3 are infected? • Most have latent, or inactive, TB • Only 10% who are infected will become sick with active TB
In terms of chemical exposure, what is the maximum concentration level standard set for wildlife? What is the standard for humans?
• The standard for wildlife is set at 1/10 of the LD50 • The extra-safe standard for humans is set at 1/1000 of the LD50
What are the 3 leading causes of death in the U.S. today? What are all three of these associated with?
• Today in the U.S., the 3 leading causes of death are: • Cardiovascular disease • Cancer • Chronic obstructive pulmonary disease of the lungs • All of the above are associated with aging
How is the LD50 of a chemical usually expressed? Given that the LD50 of caffeine is 200mg/kg, how many grams of caffeine would have to be ingested by an 80 kg person in order to have a 50% chance of dying?
• Usually expressed in terms of mg/kg (milligrams of chemical per kilogram of body mass) • Ex - LD50 for aspirin is 1750 mg/kg • Aspirin is usually taken in 325 mg tablets, 1750/325 = 5.5 tablets per kilogram • So if you weigh 60 kg (132 lbs), you would have to ingest 60 x 5.5 = 330 tablets to have a 50% chance of dying
What is hepatitis? How is it transmitted? What 2 things can happen to a person infected by hepatitis B? How can we prevent hepatitis B?
• Viral infection of the liver, transmitted in the exact same way as HIV, through infected body fluids • Infection can cause liver cancer or cirrhosis (scarring of the liver, which prevents its proper function) • A vaccine exists for hepatitis B
Without treatment, about what fraction of people with active TB die? What are 3 ways to control the spread of TB?
• Without treatment, about ½ of the people with active TB die from bacterial destruction of lung tissue • TB strikes 8.8 million people per year • 1.4 million die per year • 84% of deaths in LDCs • Someone dies of TB every 23 seconds • How is the spread of TB controlled? • Immunization • Quarantine • Treatment with antibiotics
How can the spread of cholera be controlled? What are some ways to improve sanitation?
•How can spread of cholera be controlled? • Improved sanitation • Don't dump untreated sewage into drinking water supply • Don't defecate in water supply • Treat sewage to remove/kill bacteria • Boil drinking/cooking water • Shut down shellfish beds in cholera-infected areas • Adequate hand washing
What were the 3 leading causes of death in the U.S. in 1900? What type of diseases are all three?
•In the U.S. in 1900, the 3 leading causes of death were: • Pneumonia and influenza • Tuberculosis • Gastritis and colitis (diarrhea) • All of the above are infectious diseases caused by microorganisms
