ENVR 1402 - CH. 8
True or false: All species have approximately the same reaction to a specific compound.
False
True or false: Conservation medicine refers to efforts by biologists to treat sick or injured wildlife.
False
True or false: Ecological diseases refer to infectious diseases that strictly affect wildlife or cause damage to habitats.
False
Perfluorocarbons, also known as ______________, have been used for coatings, insulation, computer parts, cosmetics, and propellants.
PFCs
POPs, or ______________ _____________ ______________, are dangerous because they don't degrade quickly and cells readily take them up.
Persistent Organic Pollutants
Allergies, headaches, and chronic fatigue due to poorly ventilated indoor spaces contaminated by toxins, such as formaldehyde released from carpeting, furniture, and other building materials can result in ______________ _____________ ______________
sick building syndrome
Adopting the precautionary principle in regulating environmental toxins ______.
- suggests a "better safe than sorry" approach of social responsibility to protect the public from harm in the face of scientific uncertainty - requires manufacturers to show that a substance is not dangerous before it is introduced into the marketplace
Which of the following are environmental disease (health) agents?
- Air pollution - Cigarette smoke - Trauma from road accidents
Setting environmental health policy is challenging because ______.
we are exposed to many sources of harm, and it is difficult to separate the effects of different hazards in order to evaluate their risks accurately
Which of the following statements about chronic and acute exposure and effects are correct?
- Acute exposure involves a single contact with a toxic chemical. It may last a few seconds or a few hours. - Chronic exposure involves continuous or repeated contact with a toxic substance over a long period of time (months or years).
Which of the following statements accurately reflect how allergens affect us?
- Allergens activate the immune system. - Allergens act as antigens and stimulate the production of specific antibodies.
Which of the following statements about global health trends are true?
- Chronic conditions such as cardiovascular disease and diabetes are increasing and spreading to poorer populations. - Infectious diseases such as diarrhea are on the decline globally.
Today health agencies calculate DALYs rather than mortality rates as a measure of disease burden because ______.
- DALYs are a more complete measure combining premature deaths and the loss of a healthy life resulting from mental illness or physical disability - mortality data fail to capture the impacts of nonfatal outcomes of disease and injury on human well-being
Why is diet a consideration in health?
- Diet-related obesity can lead to illnesses such as diabetes and cardiovascular disease. - Vegetables, whole grains, and other healthy foods can boost our ability to tolerate toxins.
Which of the following factors do policymakers consider most important in setting an effective environmental health policy?
- Differences between acute and chronic exposures - Different sensitivities among those exposed to the toxins - Combined effects of exposure to multiple toxins
Which of the following statements accurately describes how endocrine disrupters affect us?
- Endocrine disrupters may cause feminization of males. - Endocrine disrupters may interfere with growth and development. - Endocrine disrupters may cause reproductive dysfunction in females.
The leading reasons for nonrational risk perception include ______.
- misunderstanding probabilities about harm from a hazard - personal ignorance about the hazard - political or economic interest related to the hazard
Which of the following statements are true about how people apply probability in determining how much risk to accept and when to avoid exposure to certain risks?
- For most people, a 1 in 100,000 chance of dying from some risk factor is often a threshold for changing what they do. - Most people will tolerate a higher probability of occurrence of an event if the harm caused by that event is low.
Which of the following statements correctly describes how factors related to the individual influence how she or he responds to toxins in the environment?
- Immunological status affects susceptibility to toxins. A healthy individual may be insensitive to doses of toxins dangerous to someone who is ill. - Age affects susceptibility to toxins, as chemicals that might be relatively harmless to adults may be dangerous to young children.
Which of these statements correctly describes trends in child mortality?
- It is declining globally. - It remains higher in sub-Saharan Africa than elsewhere. - Clean water and improved sanitation support the declining trends.
The dose-response curve showing LD50, as provided here, describes which of the following ideas?
- Members of a population vary in sensitivity to a toxin. - LD50 is the dose of the toxin that is lethal to half the population. - Most organisms tolerate some exposure to a toxin but ultimately the dose gets large enough to kill them.
What can be concluded about policy decisions addressing hazardous and toxic nutrients based on the U.S. Environmental Protection Agency's assessment of relative risks to human welfare?
- Our focus on reducing pollution to protect human health has neglected risks to natural ecological systems that may be of greater ultimate importance. - Policy decisions about toxins must address how such materials affect not just humans but also organisms that define and maintain our environment.
The odds of being involved in a car accident are about 1 in 100 while the odds of being involved in an airplane accident are about 1 in 5,000. Which of the following statements explains why, despite these probability calculations, people perceive driving as less risky and are more accepting of the associated risks?
- People tolerate familiar risks, despite the high probability of harm, because they often downplay the risk associated with familiar activities. - People tolerate high risks in activities of their choosing, as they often have an exaggerated view of their abilities to control fate.
Which of the following statements are reasonable conclusions that can be drawn from a recent headline that announced the discovery of 23 pesticides in 16 food samples?
- Pesticide residues are not necessarily harmful, for a substance produces a harmful effect only if it reaches within the body in a high enough dose. - The mere presence of a toxin is insignificant without considering how much is there, where it is located, how accessible it is, and who is exposed.
Which of the following are true about the effects of exposure to carcinogens?
- The U.S. EPA estimates that 200 million Americans live in areas where cancer risk from environmental carcinogens is ten times higher than normal. - Exposure to carcinogens can result in invasive, out-of-control cell growth that can cause malignant tumors.
Of the many factors that determine whether a particular chemical will prove to be dangerous, which of the following are based on the nature of the chemical agent itself?
- The chemical agent is not biodegradable and thus is persistent in the environment. - The chemical agent is water-soluble.
The science involved in determining whether endocrine disrupters are harmful shows how establishing public policy is difficult. Which of the following statements correctly identify reasons why the debate currently surrounds regulating endocrine disrupters?
- The chemical industry disputes the need for testing, and industry-funded scientists point to contradictions and uncertainties in published studies. - Data on which chemicals are endocrine disrupters are not definitive.
Which of the following accurately describe mutagens and their effects?
- The damage to genetic material by mutagens can lead to birth defects if the exposure occurs during fetal development. - Though cells have repair mechanisms to restore damaged DNA, there is no safe threshold for exposure to mutagens as the repair process may be flawed. - Mutagens are agents such as chemicals or radiation that damage DNA.
In assessing the danger of toxic substances, which of these statements are true?
- The dose makes the poison. - Our increasing ability to detect traces of a substance sometimes means that though we can detect it, the level may be too low to cause harm.
Choose the statement that correctly describes HIV and HBV.
- They are both caused by viruses. - HIV is more lethal.
White-nose syndrome is ______.
- an ecological disease - caused by a fungus that thrives in cool, moist caves where bats hibernate - possibly spread by humans from one cave to another on their shoes and clothing
Declines in child mortality are largely a result of ______.
- better nutrition - improved sanitation - educating women
Debates in establishing environmental health policy include whether to ______.
- demand protection from every potentially harmful contaminant or accept some exposure as our bodies can repair some damage - establish acceptable toxin levels at the highest amount that does not cause measurable effects or as low as technically feasible
All toxic substances are hazardous, but all hazardous substances are not toxic. This is because, unlike toxic substances, hazardous materials ______.
- do not damage or kill living organisms by reacting with cellular components to disrupt metabolic functions - must be handled carefully in large doses, but they can be rendered relatively innocuous by dilution, neutralization, or other physical treatment
Chytridiomycosis (or chytrid fungus) is an ecological disease that affects amphibians and is ______.
- dramatically reducing frog populations in many areas - spreading worldwide
Contrary to the risk probabilities, we are often willing to accept far greater risk than the general threshold ______.
- for activities we enjoy or find profitable - when risks are known and we feel in control of the outcome
PFCs are persistent chemicals, so they are ______.
- in the blood of nearly everyone in the United States - found even in remote and pristine areas of the world
When a dose-response curve for a particular toxin shows a threshold for the response, it generally suggests ______.
- the presence of a defense mechanism that prevents the toxin from reaching its target or repairs the damage that the toxin causes - that some minimal dose is necessary before any effect can be observed
Match the concentrations of DDT to where that concentration might be found based on the level of biomagnification.
0.003 ppb - DDT in water 0.04 ppm - Zooplankton 0.5 ppm - Small fish 2 ppm - Large fish 25 ppm - Ospreys
Rank the order of the following causes of death, putting the lowest risk of death for a person in the United States on bottom and the highest risk of death at the top.
1. Cancer 2. Car accident 3. Drowning 4. Dog attacks
DDT is a well-known case of biomagnification in the environment. Rank the stages in biomagnification of DDT, putting the earliest stage on top.
1. DDT is deposited in water from agricultural runoff 2. Zooplankton consume DDT 3. Small fish eat zooplankton 4. Larger fish eat smaller fish 5. Ospreys eat larger fish
Which of the following is an example of a synergistic effect?
Asbestos exposure and smoking each increase lung cancer rates 20-fold. Asbestos workers who smoke, however, have a 400-fold increase in cancer rates.
What factors make emergent diseases a special problem?
At times we lack the medicines with which to treat them, as some emergent diseases are caused by drug-resistant strains of a pathogen.
Which of these sentences properly describes the difference between bioaccumulation and biomagnification?
Biomagnification occurs because of bioaccumulation.
Match the mechanism of eliminating toxins to the body part that is responsible for the action.
Detoxification - Liver Exhaling excess carbon dioxide - Lungs Excreting water-soluble salts and other substances - Kidneys
Interpret this graph by matching each label to the correct line in the graph.
Dose (amount of experience) - Horizontal (x) axis Response - Vertical (y) axis Response curve representing a constant rate of response with increasing doors - Line b Response curve representing no response for low doses - Line c
Which of these is not a consideration of toxicology?
Eradication of diseases such as polio or smallpox
Match the examples to chronic or acute effects and exposures.
Exposure to radiation during an x-ray for a broken foot - Acute exposure Developing radiation sickness after exposure to radiation - Acute effect Exposure to background radiation, like from radon gas - Chronic exposure Developing lung cancer after exposure to radiation - Chronic effect
Which of the following statements accurately explains why tissue repair mechanisms may make those tissues more susceptible to cancer?
Rapid cell reproduction replaces damaged cells in tissues, but the more cells reproduce, the greater the chances are that they may become cancerous.
Each factor listed below plays a role in determining environmental toxicity. Match each of the following factors to how it influences whether a particular chemical will prove to be dangerous.
Factor related to the toxic agent - Composition and reactivity of the chemical Factor related to the exposure - Dose and frequency of contact with the chemical Factor related to the organism - Immunological status at the time of exposure to the chemical
True or false: Mortality refers to being ill, whereas morbidity refers to dying from a disease.
False
______ is a condition that is associated with drinking during pregnancy that results in a cluster of symptoms including craniofacial abnormalities, developmental delays, behavioral problems, and mental defects, which last throughout a child's life.
Fetal alcohol syndrome
Which of the following statements about the potency (strength) of toxic substances is true?
For some toxic substances, a millionth of a gram (an amount invisible to the naked eye) can be lethal.
Match the persistent organic pollutant (POP) of current concern to its source.
Glyphosate - Used as an herbicide, Roundup Chloropyrifos - Used as a pesticide Dicamba - Used as an herbicide; a plant hormone Bisphenol A (BPA) - Used to produce plastic-coated items such as linings of cans and bottles, tooth-protecting sealants, and water pipes
Significantly more people have HBV (hepatitis) than HIV, but they are less likely to be treated for it. Why?
HIV has been much more publicized.
Match the following causes of death with the lifetime chance of dying that way in the United States.
Heart disease and cancer - These have risks of 1 in 6-7 Car accidents and firearm assaults - These have risks between 1 in 103 to 1 in 285 Dog bites and bee, wasp, or hornet stings - These have risks between 1 in 46,562 to 1 in 115,111
Which of the following groups of people is most likely to have an increased exposure to toxic chemicals because of their job responsibilities?
Industrial workers
What characteristics define an emergent disease?
It has not been previously known or has been absent for at least 20 years.
What is the current trend in the worldwide mental health disease burden?
It is rising in both developing and developed countries.
The dose-response curve shown here describes which of these ideas?
Members of a population vary in their level of sensitivity to a toxin.
Which of the following characterizes Chytridiomycosis?
Most amphibian species are susceptible to the fungus that causes Chytridiomycosis, which is spreading rapidly likely due to environmental changes.
What does the saying "the dose makes the poison" mean?
Most substances are toxic at some level of exposure depending on the substance and the nature of the exposure.
______ are chemical agents that damage or alter DNA, which can result in birth defects during fetal development or tumor growth in later life.
Mutagens
Which of the following important considerations in setting environmental health policy is most often overlooked?
Potential harm to other species or entire ecological systems
What does the image depict in the context of environmental toxicology?
Potential routes of exposure to toxins in the environment
What is a probability calculation and how is it used in risk assessment?
Probability is a calculation of the statistical danger of a risk, and this information can help us decide which risks to tolerate and which to avoid.
Which aspect of antibiotic resistance development in microbes is depicted in this image?
Random genetic mutations create antibiotic-resistant individuals that survive and multiply to develop into an antibiotic-resistant colony.
Match the dietary consideration to its positive influence on a particular health condition.
Reduce the amount of salt and animal fat in your diet - Reduced cardiovascular disease Includes pectins, vitamins (like A, C, and E), and cruciferous vegetables (like cabbage and broccoli) in your diet. - Reduced cancer risk Eat fewer calories and exercise more - Reduces obesity-related illnesses Stop drinking alcohol during pregnancy - Reduced risk of fetal alcohol syndrome
Why are animals still used to test toxicity of substances?
Tests on living animals are more reliable than other tests.
Which of the following is not a concern of environmental toxicology?
The study of the effects of flammable chemicals on forests
Which of the following applies to ecological diseases?
They affect wildlife populations, such as bats and frogs.
What are the qualities of PFCs that make them so useful?
They are slippery, heat-resistant, and durable.
Which of the statements below accurately captures the relationship between toxicity and potency?
Though categorizing toxins based on potency is useful, it is complicated by differences in individual and species reactions to particular chemicals.
Match each of the potential toxins listed below to their most likely routes of exposure.
Toluene and formaldehyde from cigarette smoke - Inhalation (respiratory tract) Pesticide residue on food - Ingestion (gastrointestinal tract) Endocrine disruptors like BHA in facial moisturizers - Absorption (dermal) Certain pharmaceuticals, vaccines, and drugs - Injection (Intramuscular)
Match the term with its correct definition.
Toxic substance - These substances damage or kill living organisms because they react with cellular components to disrupt metabolic functions. They are often harmful even in extremely dilute concentrations Hazardous substances - These substances are dangerous because they are flammable, explosive, acidic, caustic, irritants, or sensitizers. Many of these materials can be rendered relatively innocuous by dilution, neutralization, or other physical treatment
Correctly match the environmental disease agent to its example.
Trauma - Car accidents Pollution - Noise Toxins - Lead Radiation - UV rays
True or false: According to the World Health Organization (WHO) definition of health, we are all ill to some extent.
True
True or false: Most people in industrialized nations have PFC residues (perflurooctanoic acid) in their blood.
True
True or false: Our bodies often reduce the effects of toxic substances by eliminating them through our breath, sweat, and urine.
True
True or false: Sick building syndrome refers to symptoms such as headaches, allergies, and chronic fatigue caused by a variety of toxins that build up in poorly ventilated indoor spaces.
True
True or false: The World Health Organization (WHO) estimates that though 90 percent of all disease burden occurs in developing nations only about 10 percent of health care dollars are spent there.
True
True or false: Wind turbine syndrome is considered a psychogenic condition because people who are opposed to wind turbines often claim that noise and shadow flicker caused by moving turbines make them sick even though there is no medical evidence for cause and effect.
True
Solubility is important in determining how a substance travels and is absorbed. Which type(s) of chemicals travel through the environment most easily?
Water-soluble
Chemicals are generally divided into oil-soluble and water-soluble types. Match each type of substance to its characteristic.
Water-soluble types - These substances move widely in the environment and also have ready access to body cells as their solvent is ubiquitous Oil-soluble types - These substances need a carrier molecule to move through the environment, but once they are inside cells they likely accumulate and persist
What is the determined cause of colony collapse disorder?
We don't know.
You and your parents may disagree about the risk associated with your exposure to tobacco or alcohol. What is the most likely reason for the disagreement?
We perceive risk differently, depending on control, interests, or context.
Which of the following correctly characterizes white-nose syndrome?
White-nose syndrome is a fungal disease that is devastating bat populations, causing mortality of 90 percent or more in infected colonies.
In the graph shown, match each dose-response curve with what it represents about the possible response at low doses of exposure to a toxin.
a - Some of the population responds, even at zero dose of the toxin, suggesting that some other factor in the environment also causes this response b - Shows a linear relationship from zero exposure to the highest dose suggesting that exposure to such toxic agents, no matter how small, carries some risks c - Dose must be above a threshold level before anyone in the population shows a response which suggests the presence of some defense mechanism against the harmful effects of the toxin
A pandemic is ______.
a worldwide (or very widespread) epidemic
Indoor and outdoor ______________ pollution contributes to millions of deaths every year. This number doesn't include people killed by smoking tobacco.
air
Public policies regarding toxicity are based on the results of ______, and scientists still have the most confidence in this method.
animal testing
CRE is a lethal bacteria that is resistant to ________________; it causes <5% of all hospital infections but is fatal in about 50% of the cases. (Use one word for your answer.)
antibiotics
Some allergens act directly as ______, and the immune system recognizes them as foreign, stimulating the production of specific antibodies.
antigens
The term disease refers to ______.
any abnormal change in body conditions that impairs normal functions
Colony collapse disorder is a persistent epidemic that affects ___________________. (Use just one word for your answer.)
bees
The idea of hormesis, the nonlinear effect of a toxin in which a low dose is ______ and high dose is ______, was misapplied in a 2018 rule proposed by the EPA that suggested a little pollution was beneficial to health.
beneficial; harmful
The selective absorption and storage of a great variety of molecules inside cells and tissues at levels that are higher than in the environment is called ______.
bioaccumulation
As shown in the figure, every organism in the Lake Michigan food chain has some DDT in their body tissues at concentrations higher than in the environment due to ___________________, whereas the reason that gulls, who are tertiary consumers, have about 240 times the concentration of compounds as compared to the small insects sharing the same environment is due to _________________
bioaccumulation; biomagnification
When the toxic burden of organisms at a lower trophic level is accumulated and concentrated by a predator in a higher trophic level it is called ______.
biomagnification
Substances that cause invasive, out-of-control cell growth resulting in tumors are called ______.
carcinogens
Neurotoxins are poisons that affect us by ______.
causing nervous system damage
Lead was banned from gasoline and paint in the 1970s and health problems associated with its exposure have dropped significantly since then. However, a huge health scare in Flint, Michigan, occurred in 2016 when children were exposed to lead through ______.
contaminated drinking water
Regulators struggle with how to set acceptable pollution levels based on the dose-response curve because ______.
costs may increase significantly to protect the very small number of highly sensitive individuals at the extreme end of the curve
Because organs such as your skin and liver make frequent repairs, they are also more likely to ______.
develop cancerous tumors
The heaviest burden of illness is borne by ______.
developing countries where many people cannot afford adequate health care or to live in a healthy environment
The DALY measure is the ______.
disability-adjusted life years, which evaluates the total cost of disease, not just how many people die
Nearly all substances are toxic depending on the amount, delivery rate, and method. This idea is summarized in the statement "the ___________________ makes the poison."
dose
The study of toxicology ______.
draws from many disciplines, including biology, biochemistry, pharmacology, among others
The 2014 epidemic of ______ in western Africa infected approximately 20,000 people and killed 8,000.
ebola
Environmental health policies need to address ______________ because we may be destroying cycles that support human life if we don't protect different types of organisms.
ecosystems
The ________________ principle is being used to regulate toxins by requiring manufacturers to prove that substances are safe rather than requiring regulators to show that they are dangerous.
precautionary
Because the chemical industry thinks they are uncalled for, and toxicologists argue that there are problems with the necessary tests, the regulation of _______________ disrupters has been difficult to enact.
endocrine
The estrogen-like compound that acts as a substitute hormone and disrupts gene expression, as shown in the image, is a(n) ______.
endocrine disrupter
What is the current concern with using Sprague-Dawley rats in toxicology studies? They are much less sensitive to ______ than regular rats, so studies using them are highly suspect.
endocrine disrupters
The field that specifically deals with the interactions, transformation, fate, and effects of natural and synthetic chemicals in the biosphere, including individual organisms, populations, and whole ecosystems is ______.
environmental toxicology
The pattern of mental and physical defects that can develop in a fetus in association with high levels of alcohol consumption during pregnancy is called _________________ ______________________ syndrome.
fetal alcohol
80% of antibiotics used in the United States are _______.
for livestock
Antigens are ______.
foreign materials that stimulate the production of specific antibodies
The idea that a small amount of radiation may stimulate DNA repair, whereas a large amount of radiation causes cancer, is an example of _____________________. However, that does not imply that low doses of any toxin is good for health.
hormesis
Morbidity refers to _____________, whereas mortality refers to ____________. (Use only one word per blank.)
illness, disease or sickness; death
Disease refers to ______.
impairment of body functions
The POPs of greatest concerns include substances such as chloropyrifos and glyphosate; we are exposed to them primarily by ______ because they are used in the production of ______.
ingestion; food
Conservation medicine ______.
is an emerging discipline that seeks to understand how environmental changes threaten our health and the environment itself
What persistent pollutant formerly was used in paint and gasoline and is linked to numerous health concerns such as cancer, reproductive problems, mental issues, behavior problems, and deformities?
lead
The term LD50 refers to the ______.
lethal dose of a chemical for half of the population
Issues associated with _______________ heath may take up to 15% of the worldwide disease burden by 2020 as conditions such as depression are growing more prevalent in both developed and developing countries.
mental
The 2015 outbreak of the Zika virus was especially concerning as infected pregnant mothers were having babies with ______.
microencephaly
The Zika virus is most commonly transmitted by
mosquitos
The Sprague-Dawley rat is ______ to endocrine disrupters than ordinary rats, so studies using them are not reliable.
much less sensitive
A metabolic poison that specifically attacks nerve cells is a _______________
neurotoxin
Trends in obesity-related illnesses such as heart disease and diabetes show that such diseases are ______.
no longer just for the wealthy, as they are now becoming common in the developing world
Biomagnification, in the case of a fish-eating osprey, refers to the fact that the ______.
osprey accumulates compounds stored by all prey lower in the food chain
A majority of the MRSA (methicillan-resistant Staphylococcus aureus) infections recorded in 2011 were related to ______.
outpatient hospital procedures
Antibiotics for humans are generally ______ in the United States.
over-prescribed misused
The Black Death, the 1918 influenza, and the H1N1 flu virus were all ______, as they caused widespread and worldwide infections.
pandemics
A metal such as lead that is stable, resistant to degradation, and can impair children's health long after exposure and far from where it might have first been used is of concern because of its _______.
persistence
Another term for toxin is ______.
poison
Risk is defined as the ______.
possibility of suffering harm or loss resulting from a given action
Risk assessment is the ______.
process of estimating the threat a particular hazard poses to human health
Outbreaks of health problems that have a psychological rather than a physical basis are referred to as ______.
psychogenic conditions
The possibility of suffering harm or loss resulting from a given action is referred to as ______.
risk
In 1973, the FDA required that cancer-causing compounds must not be present in meat at concentrations that would cause a cancer risk greater than 1 in a million lifetimes. This decision of the FDA was based on ______.
risk assessment
Microbes acquire resistance to antibiotics through different processes that include random mutations and ______________ reproduction.
sexual
The World Health Organization's definition of health includes ______ wellbeing.
social mental physical
Persistence of chemicals can be a concern for health because such ______.
stable chemicals are resistant to degradation and can cause problems long after application and far from the sites where they were originally used
Persistent organic pollutants (POPs) are a concern because being ______.
stable, they do not degrade easily and have become extremely widespread in the environment
In environmental toxicity studies, when an interaction between two substances results in one of them exacerbating the effects of another by 20-fold it is called a(n) ______ interaction.
synergistic
Fetal alcohol syndrome is a pattern of mental and physical defects that can develop in a fetus when a mother drinks alcohol during pregnancy. This specifically makes alcohol a ______.
teratogen
Chemicals or other factors that specifically cause abnormalities during embryonic growth and development are called ___________________
teratogens
Bioaccumulation is ______.
the selective absorption and storage of a great variety of molecules inside cells at levels that are higher than the environment
A defense mechanism that repairs the damage caused by a toxin would create a _______________ response curve; a minimal dose is necessary to induce an observable effect.
threshold
Poisons that are produced naturally are called ____________ substances.
toxic
Allergens are substances that affect us by ______.
triggering a response in our immune systems
People living in ______ areas, especially in ______, are particularly susceptible to death linked to air pollution.
urban; China
Differences in physiology, metabolism, and body size result in species reacting ______ to a specific compound, which makes human risk difficult to estimate.
very differently
Ebola hemorrhage fever is caused by a ______, and was the source of an epidemic in western Africa in 2014.
virus
