Environmental Health and Toxicology Flashcards
1
Q
A
2
Q
What factors speed up the leaching of harmful chemicals in plastics (polymers) into food and drink?
A
those that promote breakdown - extreme temperatures, ultraviolet exposure, prolonged contact with acidic liquids
3
Q
Bisphenol A (BPA)
A
within epoxy resin that is used to line the insides of metal cans and water pipes, + enamels, varnishes, adhesives, dental sealants, and polycarbonate plastic; enter the air, food, and water and shown to be harmful
4
Q
Polycarbonate plastic
A
a hard and clear type of plastic found in water bottles, food containers, CDs/DVDs, electronics, baby bottles and toys
5
Q
Phthalates
A
hormone-disrupting chemicals that enter the air, food, and water; used to soften plastic (as in bottles, food packaging, perfumes, toys, etc.)
6
Q
According to the CDC, over ___ % of Americans have detectable concentrations of BPA or phthalates in their urine.
A
90
7
Q
How do we know that exposure to BPA and phthalates is practically continuous in the U.S.?
A
they pass through the body in just a few hours but are still detected in a large amount of people
8
Q
Only studies with rats and mice, not humans, have shown health effects associated with exposure to BPA and phthalates.
A
false
9
Q
What health issues have been strongly correlated with BPA or phthalate exposure?
A
birth defects, breast cancer, lower sperm count, diabetes, cognitive impairment in children exposed during pregnancy
10
Q
What could potentially make even minimal exposure to BPA or phthalates harmful?
A
they cause effects at levels even lower than those set by regulatory agencies; mimic certain hormones, including sex hormones that work at low concentrations
11
Q
What have some responses been to the health risks posed by endocrine-disrupting chemicals in plastics?
A
some chemical/manufacturing industries have insisted upon their safety and supplied industry-sponsored research (biases likely); some countries have banned them and others have restricted them from certain products (like products for babies and children); some companies voluntarily remove them
12
Q
One study found that ___ of fast food packaging, especially those with coatings for grease resistance, have fluorinated chemicals that might also be endocrine disruptors.
A
1/3
13
Q
Environmental health
A
an assessment of environmental factors that influence health and quality of life, both natural and anthropogenic; seeks to prevent adverse effects on humans and the ecosystem and minimize impacts that do happen
14
Q
What are the four main types of environmental health hazards?
A
physical, chemical, biological, cultural
15
Q
Examples of physical environmental health hazards
A
excessive UV exposure (tied to skin cancer, cataracts, immune suppression); earthquakes, volcanic eruptions, fires, floods, and other discrete events (decreased risk with emergency plans, appropriate building planning, etc.); all occur naturally
16
Q
Examples of chemical environmental health hazards
A
some pharmaceuticals, disinfectants, pesticides (synthetic); venom (natural); hydrocarbons, lead, asbestos (natural and processed for use)
17
Q
Examples of biological environmental health hazards
A
parasites and infectious diseases (cholera, tuberculosis, malaria, influenza); from ecological interactions between organisms (especially in developing countries with widespread poverty and lack of healthcare)
18
Q
Vector
A
an organism that transfers a parasite to the final host (otherwise parasites directly attack the host)
19
Q
Examples of cultural environmental health hazards
A
smoking, workplace hazards, drug use, forced risks like those with less economic resources and political power living near a hazardous waste site; come from place of residence, occupation, socioeconomic status or behavior
20
Q
___ causes the majority of human deaths despite technological advancements.
A
disease
21
Q
Over ___ of all disease-related deaths are noninfectious, instead coming from genetics, the environment or lifestyle choices.
A
1/2
22
Q
Which six disease types cause 80% of all deaths from infectious disease, in order of most to least deaths caused?
A
respiratory infections, diarrheal infections, AIDS, tuberculosis, malaria, meningitis
23
Q
About infectious diseases
A
cause fewer deaths than noninfectious but strike at all ages; cause about 17% of worldwide deaths and about 1/2 of all deaths in developing nations
24
Q
What are the main factors that allow novel infectious diseases or strains to spread?
A
global mobility and dense populations
25
Virulence
how fast a pathogen spreads, how readily it mutates and its level of harm; controlled by DNA
26
What can decrease the spread or effects of infectious diseases?
immunization, public sanitation, access to clean water, food security, public education campaigns, healthcare access
27
How was the prevalence of waterborne diseases effectively decreased?
with help from the UN + national governments + aid organizations; decreased the ingestion of water and food contaminated by feces with public education on how to sterilize water, infrastructural projects to drill wells and create water treatment facilities, access to clean water for 91% of people across the globe, and providing composting toilets (for areas without piped water)/sewer systems/septic systems/public latrines
28
The 2017 goal by the UN is to get access to clean water for all people on the planet by ___.
2030
29
Toxicology
examines how poisonous chemicals affect the health of humans and other organisms
30
Toxicity
the degree of harm a chemical can inflict
31
Toxicant
a toxic substance, i.e., poison
32
Any chemical may have a negative impact with enough exposure.
true
33
Environmental toxicology
deals with toxic substances from the environment or discharged into the environment; increasingly studied as the ability to produce new chemicals has increased; uses animals or plants as models to see ecological impacts and if human harm is possible with a substance
34
What are the top two lung cancer causes in developed nations?
cigarette smoke and radon
35
Mold
produces toxic compounds and flourishes in high moisture
36
Asbestos
formerly used for insulation in walls; harmful when inhaled
37
Lead poisoning
from pipes or leaded paint; causes cognitive problems and behavioral abnormalities, organ damage or even death; decreased with education and a phaseout of production in the 1970s
38
Polybrominated diphenyl ethers (PBDEs)
fire retardants used in computers, TVs, plastics, and furniture; evaporate at slow rates; endocrine disruptors that may cause cancer and influence nervous system development; a 2009 study in the U.S. found one type in nearly every person studied; banned in the EU in 2003 while the U.S. has placed few regulations
39
Oil oozing naturally from the ground can pose health risks.
true
40
Why is it important to weigh the risks and rewards of artificially produced chemicals?
they offer many benefits for agriculture, medicine, conveniences, commonly used materials and containing/preserving food (+ protecting against food pathogens) but they can be physically harmful; may be safe to keep using or better to replace/stop using
41
Toxins
chemicals produced in the tissues of living organisms (especially to ward off herbivores/predators), plus synthetic chemicals with toxic properties
42
Who is particularly sensitive to the intake of chemical substances, even if humans only absorb a small proportion from the environment (and many pose no harm)?
developing fetuses and babies
43
Silent Spring (Rachel Carson, 1962)
a book that drew substantial attention to the harms of pesticides for the first time, whereas previously they were sprayed indiscriminately and untested for health impacts; focused particularly on the insecticide dichloro-diphenyl-trichloroethane (DDT); synthesized studies and medical cases; helped to get DDT banned in the U.S. in 1973
44
Where is DDT still used and why?
in some developing areas with tropical climates to control disease vectors such as mosquitoes (for malaria) which pose greater threats than the insecticide itself; may be able to control using other techniques with enough research
45
It is accurate to assume that all synthetic chemicals are unhealthy and all natural chemicals are safe.
false
46
How can people be exposed to toxins by eating standard crops and meat?
traces of toxins remain in many fruits/vegetables even though humans selected for strains with less toxin content + animals may obtain toxins from plants/animals they consume and pass them to humans
47
Carcinogens
substances or forms of radiation that cause or increase the likelihood of cancer; most cases of cancer today from those in cigarette smoke; sometimes hard to identify due to long delay between exposure and detectable onset, plus not all exposed get cancer (usually has a genetic component)
48
Mutagens
substances that cause genetic mutations in DNA (most of which have little to no effect but some of which lead to problems like cancer or issues in offspring if reproductive cells are affected)
49
Teratogens
substances that cause harm to unborn organisms and may result in birth defects; ex. thalidomide, a drug developed in the 1950s to treat difficulty sleeping and nausea during pregnancy that led to organ and limb abnormalities and was banned in the 1960s
50
Neurotoxins
substances that negatively affect the nervous system, such as animal venom, heavy metals and some pesticides; ex. mercury waste dumped in Japan (1930s-1960s) contaminated fish and caused thousands to experience slurred speech, loss of muscle control, sudden fits of laughter or even death
51
Allergens
substances that cause allergies/allergic reactions by over-activating the immune system when it isn't necessary; not universally considered a toxicant since not everyone is affected and the response is not always correlated with the amount of exposure; increased production of synthetic chemicals containing these may be increasing cases of asthma
52
Pathway inhibitors
substances that interrupt vital biochemical processes in organisms by blocking one or more steps in a pathway; ex. rat poison leads to internal hemorrhaging by stopping the production of blood-clotting proteins
53
Endocrine disruptors
substances that interfere with the endocrine system; block hormonal action, accelerate the breakdown of hormones, or have a similar structure to hormones and mimic them by binding to their receptors; ex. BPA mimics estrogen
54
Toxic substances are classified by their health impacts, but a toxicant may fall into more than one of the seven categories.
true
55
How have organisms evolved to be tolerant of natural toxicants to which they have been long-exposed?
have skin, scales, or feathers as first defense; toxicants that enter the body through food/water/air are distributed by the circulatory/lymphatic or vascular system, but biochemical pathways exist that use enzymes to break them down or detoxify them; may more easily excrete those that are water-soluble; when detoxified substances cannot affect an organism they are stored in fatty tissues and cell membranes to keep them away from vital organs
56
Why might synthetic chemicals be more dangerous (on average) than natural toxicants?
organisms have experienced little long-term exposure to them and have not yet had time to evolve to handle them; effects can be severe and unpredictable
57
What factors contribute to how much a toxic substance affects the body?
genetics, current state of health, sex, age, weight
58
Why are younger organisms more sensitive to toxic substances than adults?
they are smaller and have rapidly developing organs; linear extrapolations for chemical exposure standards from adults to children done by the EPA may not protect children enough
59
Acute exposure
exposure to high amounts of a toxic substance for short periods; easier to recognize and often from discrete events; toxicity tests often reflect these effects as opposed to chronic effects
60
Chronic exposure
exposure to low amounts of a toxic substance for long periods; more common but harder to detect and diagnose, especially because it affects the body gradually
61
How can increased concentrations of a toxicant in an ecosystem affect its biological composition?
causes harm to certain organisms, decreases their numbers and in turn grows or shrinks the populations of other species that rely on or are consumed by them; also become concentrated in tissues long-term
62
Why are synthetic chemicals found even in clean areas where they aren't used?
air currents can carry them far from their release site
63
Polychlorinated biphenyls (PCBs)
an industrial chemical used in electrical equipment, paints, and plastics from its introduction in 1929 to its ban in 1979 in the U.S.; still at dangerous levels in arctic wildlife
64
Global distillation
describes how pollutants that evaporate rise high in the atmosphere at low latitudes and are carried to the poles by air currents or how pollutants in water are similarly carried by ocean currents; effect of global circulation patterns on the spread of toxicants; deposition exceeds evaporation at high latitudes
65
Findings of fast food study using National Health and Nutrition Examination Survey data (2016)
fast food may expose consumers to a higher level of dangerous chemicals than other food; positive correlation existed between consumption of fast food and urine concentration of 2 types of phthalates and quantity of food determined concentration; no statistically significant correlation found for BPA; hypothesized that the plastic in gloves and food-processing equipment released phthalates into food, especially hot and high-fat foods; industry groups (National Restaurant Association, American Chemistry Council, etc.) pointed out the levels were below EPA guidelines but according to their critics, evidence exists to show that health impacts occur at the levels found in the study
66
Pesticide drift
a phenomenon whereby pesticides themselves or airborne dust contaminated by pesticides are carried by air to sites far from fields (ex. most productive agricultural region in the world, the Central Valley of California, has decreased the populations of 4 frog species in Sierra Nevada Mountains)
67
What are some reasons why water contamination by toxicants is a significant issue?
runoff transports toxicants easily and concentrates them in small volumes of surface water; wastewater plants add toxins, pharmaceuticals, detoxification products, etc. to waterways; many chemicals are water-soluble and can enter bodily tissues (which makes aquatic animals good indicators of pollution)
68
What did a 2017 study of crustaceans in deep Pacific trenches find?
they had PCB and PDBE levels up to 50 times that of those in the most-polluted rivers
69
What factors determine how long it takes for a toxicant to break down?
sun exposure, temperature, moisture, chemical properties/design (some chemicals are made to persist)
70
Breakdown products
the results of the decomposition of a toxicant or other chemical; often less harmful but sometimes just as or more toxic (ex. DDT -> DDE)
71
What may happen if an organism absorbs or ingests a toxicant?
can quickly excrete it, degrade it to harmless products, or have it persist in the body (fat- and oil-soluble are stored in fatty tissues)
72
Bioaccumulation
occurs within a single organism when a toxicant becomes more concentrated than it is in the surrounding environment
73
Biomagnification
occurs when bioaccumulated toxins become increasingly concentrated in herbivores/predators that eat the original organism (because they eat many individuals from lower trophic levels); ex. birds of prey in the U.S. decreased when DDT caused their eggshells to thin, polar bear cubs experience immune suppression + hormone disruptions + high mortality from PCBs in milk
74
What do wildlife toxicologists do?
work in the field to take measurements, document patterns and generate hypotheses before performing controlled, manipulative experiments in the lab to test their hypotheses (ex. study on alligators in Florida observed reproductive issues in terms of eggs, gonads, and hormones; comparisons of populations in clean vs. polluted lakes (with DDT, dicofol, atrazine) showed positive correlation with exposure and health issues + lab tests showed contaminants could bind to estrogen receptors or produce an enzyme that converts testosterone to estrogen)
75
Case history
refers to studies of sickened human individuals to gain knowledge; may not help to infer the effects of rare hazards or low-concentration, minor and long-term effects
76
Epidemiological studies
large-scale comparisons among groups of people, usually exposed group vs. non-exposed group; tracks their fate for years to decades and measures deaths, diseases, etc.; test hypotheses and analyze data to measure statistical association (cannot show cause but manipulative experiments are generally unethical)
77
Dose-response analysis
refers to testing using lab animals in toxicology to quantify toxicity by the strength of effects or the number of animals affected at different doses (where a response is a negative effect); measures properties that show negative effects and plots them on a graph to create the dose-response curve; linear curve means the percentage affected/killed increases with dose (but endocrine disruptors often generate nonlinear curves); often uses higher doses relative to mass than humans would receive, then extrapolates data with a plot to see effects at lower doses and for higher masses (estimates, not 100% certain)
78
Lethal dose-50 (LD₅₀)
used in dose-response analysis; the point where 50% of the organisms tested are killed by a toxic substance; represents a gauge of toxicity (higher value = low toxicity and lower value = high toxicity)
79
Threshold dose
applies to dose-response analysis; the dose below which there is no measurable effect (does not apply for all toxic substances); often when the body's organs can fully metabolize or excrete the substance but any higher concentration overwhelms them
80
Effective dose-50 (ED₅₀)
an alternative to LD₅₀ that represents the point where 50% of the organisms tested are affected in some way besides death
81
Synergistic effects
refers to when the interactive effects (which can mean effects that add onto, subtract from, or multiply each other) of multiple hazards are more apparent than the sum of their constituent effects, making it harder to estimate their impacts; ex. DDE can promote OR inhibit sex reversal in alligators depending on the presence of other chemicals, nitrate/atrazine/aldicarb together in mice causes immune/endocrine/nervous system effects not observed with each chemical by itself; makes single-substance tests a priority but means that interactive effects are mostly unknown (complex to test for)
82
Our Stolen Future (1996)
a book that more explicitly introduced the idea that synthetic chemicals can alter hormones and act as endocrine disruptors
83
What are some trends in human health issues that are suspected to be caused by endocrine disruptors?
increased breast cancer (from higher estrogen, which may feed tumor development) and lower sperm count/erectile dysfunction
84
What is the difficulty of banning or restricting toxic substances?
usually only happens after years of testing and heavy pressure from corporations, political interests, economics and ethics can impede it
85
Risk (in toxicology)
the generally small probability that harm will result from exposure to a substance; may be perceived as larger than the statistical reality, especially when exposure cannot be controlled or effects are less understood (also smaller than statistical reality); determined from type of substance, its strength, the chance of exposure, amount of exposure, and sensitivity to it
86
Risk assessment
a quantitative measure of risk involved in different activities or substances; a way to identify issues and determine which are threats vs. safe; a study of toxicity and dose-response analysis + the extent of exposure for an individual or population (frequency, concentration, length) for chemicals
87
Risk management
decisions and strategies to decrease risk, usually handled by federal agencies; considers scientific assessment, the economy, social/political needs and values, and costs/benefits of different solutions; benefits are often economic, known, easily quantified, discrete and stable while costs are often health-related, hard-to-measure probabilities with a lack of equivalence (where a small percentage suffers a lot but most feel little effect)
88
Why might eliminating plastic packaging to remedy BPA and phthalate exposure cause more harm than good?
plastic lining in metal cans decreases corrosion and contamination, etc.; alternatives cost the industry more which would increase consumer prices
89
What are the two possible approaches to new substances, which always have an uncertain potential for harm?
1) assume substances are harmless until they cause harm as testing is long, complicated and expensive, thus putting technological innovation and the economy first; or 2) the precautionary principle, which identifies any harm before releasing the substance for use; represent two ends of a continuum; usually belief differs on where the burden of proof lies (the government, scientists, or citizens vs. manufacturers); Europe largely uses 2nd approach and U.S. largely uses 1st
90
2016 Frank R. Lautenberg Chemical Safety for the 21st Century Act
directs the EPA to require more testing of new substances before their use; expands upon Toxic Substances Control Act
91
Examples of U.S. federal agencies tracking and regulating synthetic chemicals
FDA, 1938 for foods, additives, cosmetics, drugs, and medical devices; EPA, 1947 for pesticides; OSHA, 1970 for workplace hazards
92
Why may it be safest to follow caveat emptor as a consumer (and educate oneself on the risks of products)?
available to buy does not ensure safety as some products are tested less than others; regulating organizations and agencies have faced and continue to face budget cuts
93
Toxic Substances Control Act (1976)
allows the EPA to regulate synthetic chemicals not covered by other laws, including thousands that are made or imported into the U.S.; can ban if risk is excessive; many believe it is far too weak (even with Frank R. act) as few of the chemicals included are thoroughly screened
94
2007 REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals) program in the EU
shifts the burden of proof from the government onto industry and requires imported substances exceeding 1 metric ton per year to be registered with the European Chemicals Agency
95
Stockholm Convention on Persistent Organic Pollutants (POPs), 2004
an example of an international treaty that addresses pollution; ratified by 150+ countries; targets toxic chemicals that can travel long distances and persist in the environment through bioaccumulation and biomagnification; aimed to end the use of 12 POPs that had shown to be the most dangerous by setting guidelines to phase them out and encouraging transitions to safer alternatives
96
Government regulation is often sufficient to address and resolve issues with toxic substances.
false
