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99 Cards in this Set
- Front
- Back
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Questions
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Answers;
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What are the three pillars of EH?
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Exposure science/assessment
Toxicology Environmental epidemiology |
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What are the fundamental principles of EH?
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Humans are fundamentally connected to the natural world.
Our connection to the world spans evolutionary and modern times and health consequences depend upon our ability to adapt. The dose makes the poison |
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What are methods for assessing exposure?
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Scenario modeling
Biomonitoring Direct measures (either personal or ambient measures) |
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What is exposure science?
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the quantitative measurement of exposure and exposure pathways. Understanding the pathways, frequency, duration, and magnitudes of exposure
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What is toxicology?
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understanding the link between exposure (dose) and disease using animal, in silico, high throughput assays, or other similar computer or laboratory-based studies
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What is environmental epidemiology?
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the use of epidemiology (primarily observational studies) to understand predictors of exposure or associations of exposure with environmental disease
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What are advantages/limitations of using models for assessing exposure?
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Applications: groundwater, indoor air, soil sampling at waste sites
Advantages: Inexpensive Can be prospective Disadvantages: Assumptions Validation required |
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What are advantages/limitations of using biomonitoring for assessing exposure?
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Applications: lead, dioxin, VOCs
Advantages: Biologically-relevant exposure Historical exposures Disadvantages: Requires pharmacokinetic info Potentially expensive, invasive |
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What are advantages/limitations of using direct measures for assessing exposure?
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Applications: environmental air/water pollutants, radiation, pesticides
Advantages: accurate Disadvantages: Expensive Time-consuming Cumbersome Limited range of pollutants |
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What is the difference between an exposure pathway and a route?
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A pathway is the contaminant in an environmental medium to which you can become exposued. A route is how the contaminant enters your body.
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What are the fundamentals of toxicology?
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The dose makes the poison
ADME process (absorption, distribution, metabolism, and excretion) |
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What are ways of conveying toxicity (LD50, LC50, etc)?
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What are ways of conveying toxicity (LD50, LC50, etc)?
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Are higher or lower LD50s more toxic?
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Lower LD50s
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What is a toxin?
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A toxin is a naturally occuring compound or a compound made by a living thing. Examples include botulinum neurotoxin (BoTox), pyrethrins, snake venom.
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What is a toxicant?
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A toxicant is a man-made chemical that has human toxicity. Examples include pyrethroid insecticides, pharmaceuticals, dioxins, PBCs, most commercial pesticides
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What are the fundamental principles of enivornmental epi?
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What are the fundamental principles of enivornmental epi?
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What is the "Achilles' heel" of environmental epi?
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The quality of the exposure assessment impacts the validity of an environmental epi study
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What is the exchangeability assumption?
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The morbidity in the unexposed group is the same as what the morbidity in the exposed group would have been had they not been exposed. If populations are not exchangeable, then there is confounding.
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What is the TSCA?
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Toxic Substances Control Act = control over the production, manufacture, use and disposal of toxic chemicals. A loophole in it is that a chemical is essentially safe until proven harmful. A chemical can be removed from manufacture and replaced with another chemical for which we have little data.
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What is the precautionary principle?
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Where threats of serious environmental health exist, lack of scientifid certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.
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What is the polluter pays principle?
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If someone pollutes an area, they are liable for all costs associated with remediating or cleaning the polluted area.
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What studies are most common in environmental epi?
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Observational study, because randomized studies and dosing cannot be done because of ethical concerns
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What is the diffrence between primary and secondary barriers of diarrheal disease?
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Primary = eliminate defecation in streams by behavioral modification
Secondary = sanitize water prior to consumption; handwashing |
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What are water quality, quantity, and access?
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Water quantity = the amount of water available to an individual or community
Water access = the community or individual's ability to use this water Water quality = a measure of the potability of the water for consumption. It can be a subjective or objective measure (e.g. water from the Ganges river may be considered spiritually pure but may be biologicaly impure) |
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What is cholera and how is it transmitted?
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Cholera is caused by Vibrio cholerae and is transmitted by the ingestion of contaminated water. It removes water from your body causing severe dehydration through the elimination of watery stools. Oral rehydration salts, IVs and other rehydration steps can be used to treat it, if available.
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How does near shore coastal cholera occur?
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Phytoplankton carry Vibrio cholerae which adheres to the chitin in the exoskeleton of the zooplankton that encounter it. Shellfist then acquire it and humans in near shore coastal regions ingesting shellfish can contract it and they circulate it among their communities sometimes transmitting the disease inland.
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What are some simple methods of removing cholera from water?
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She used old Sari clothes with frayed fibers that would filter out a significant portion but not all of the cholera-causing organisms. Because the infectious dose is so high (103-108), it kept the water concentration below this dose.
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What is the schistosomiasis life cycle?
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Eggs from adult worms are eliminated in feces. Eggs get into water by open defecation in or near water or as runoff from agricultural use of fertilizer. Eggs hatch and infect specific snails. The snails release the infective form of the disease in water which is then dermally absorbed by a person exposed to the water.
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What are pathways of pesticide exposure and how can we reduce these exposures?
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Occupational exposures = dermal absorption and inhalation - wear masks and protective clothing
Non-occupational exposures = ingestion with incidental exposures from home use - decrease use of harmful pesticides for produce |
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What policies and laws govern pesticide use?
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What policies and laws govern pesticide use?
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How do insecticides differ from most other pesticides?
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How do insecticides differ from most other pesticides?
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How does lead distribute in the body?
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It goes to the blood, soft tissues, and bones
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How can we reduce lead exposure?
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No more lead-based paint!
Lead-free gasoline |
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What are biomagnification and bioaccumulation?
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Biomagnification = increase in concentration of a substance that occurs in a food chain
Bioaccumulation = occurs within a trophic level, and is the increase in concentration of a substance in certain tissues of organisms' bodies due to absorption from food and the environment |
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What is the grasshopper effect?
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The process by which persistent organic pollutants (POPs) are transported from warmer to colder regions of the Earth, particularly the Poles and mountain tops
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What are primary ways PCB contamination occurs?
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Polychlorinated biphenyls are used as dielectric and coolant fluids, in capacitors, transformers, and motors and as flame retardants.
PCBs released into Hudson River and reached high levels in fish |
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What are the results of climate change?
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Raise in earth temperature
Rise in sea level Increased precipitation |
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What are atmospheric results of climate change?
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Elevated greenhouse gases in atmosphere trap infrared head within the atmosphere
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Why do we perform risk assessment?
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to try to understand how much of a substance a population has been or will be exposed to
to make decisions related to environmental exposures and health to determine factors that put segments of the population at higher risk to chemical toxicity to help establish dose-response relationships in the "real world" |
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What are the components of risk assessment?
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Hazard identification
Dose-response relationship Exposure assessment Risk characterization |
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Where are risk assessment strategies uncertain?
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Default assumptions may be flawed
High dose tox studies extrapolated to lower dose (real world) scenarios Epi data from observational studies where causality is hard to establish Cancer slopes assume linear risks at low doses (extrapolated from high doses) and do not account for mechanisms such as thresholds or triggers of exposure |
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How does uncertainty play into risk?
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It is factored in when calculating risks
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What is the difference between risk assessment for cancer and non-cancer endpoints and how are they derived?
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Non-cancer risks are determined by dividing the lifetime average daily dose (LADD) by the reference dose to calculate a hazard quotient. Because reference doses aren't available for cancer endpoints, cancer potencies are calculated in epi or tox studies and are multipled by the LADD to estimate risk. Crancer slopes assum linear risks at low doses (extrapolated from high doses) and do not account for mechanisms such as thresholds or triggers of exposure.
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What are methods of risk communication?
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Accept and involve the public as a legitamate partner
Plan carefully and evaluate your efforts Listen to the public's concerns and deal with conflicts of interests Be honest, frank, and open Coordinate and collaborate with other credible sources Meet the needs of the media Speak clearly and with compassion |
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Define an NOAEL and how it is established.
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No observed adverse effects levels. Established typically using animal but also human studies. The most sensitive effect (i.e., the effect observed at the lowest dose) it typically used to establish the NOAEL. Below the NOAEL, not effect is observed.
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How are reference doses calculated?
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The NOAEL value divided by several uncertainty (or safety) factors to account for species differences, populationheterogeniety, adult to children, etc
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How is risk quantified?
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As a probability with much uncertainty typically containe within the number (1 in 10)
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What are several barriers to risk communication?
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Uncertainty
Distrust Filtering of information Psychosocial factor |
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How do cross-sectional studies hamper health-related studies?
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We don't know if exposure came before the disease
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Describe eco-sanitation (or dry sanitation) and pros/cons of it.
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Dehydrating and composting of waste typically using special toilets to separate liquid and solid wastes. It uses less water and recycles solid waste for use in agriculture. Composting, however, may not always eliminate pathogens even though elevated temperatures are maintained during composting, it is sometimes logistically difficult and sometimes not accepted culturally.
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What is the most important change that will improve SWASH in developing areas?
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Beavhioral change is the most important but is more powerful when coupled with infrastructure development
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What is point source vs. point of use contamination?
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Water that is contaminated where you obtain it (eg. a river with fecal matter) is point of source contaminition. Point of use contamination occurs when you sample the water for use (e.g., dip hands with fecal matter into water to scoop up a drink of water).
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What is sanitation and what is hygiene?
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Sanitation is the treatment of waste by hygienic disposal or recylcling and this is typically community-based. Hygiene is teh practice of keeping oneself and surrounding area clean which is typically practiced on an individual level.
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What are the steps involved in WASH intervention research?
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Determine the baseline; identify aspects that are most hazardous
Develop intervention (behavioral or infrastructure or both) Assess the outcome of the intervention. Are more interventions required? Evaluate. Make intervention sustainable. |
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Who first isolated "Vibrio comma" in pure culture that was later found to be the etiologic agent of cholera (Vibrio cholerae)?
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Robert Koch
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When was the vibrio toxin isolated?
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1959
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Is cholera viable when not in a culturable stage?
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yes, it has a unique dormant stage.
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What would be considered a negligent response to ID?
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Treatment of symptoms or disease without trying to break the cycle of reinfection.
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What are some barriers to controlling schistosomiasis?
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Lack of modern detection techniques
Modesl that do not consider uncertainty, bias, and other characteristics such as spatial and climate change Lack of sustainable interventions that can be easily implemented |
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Describe one sustainable schistosomiasis control mechanism that is being tested in China.
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Anaerobic digesters offer co-benefits by providing sanitation, mitigation of helminths and the generation of gas for use indoors, for example, with cooking. The anaerobic conditions of sewage digestion kill >99% of helminth ova and the process generates gas that can be pumped in house.
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What is thought to be responsible for the "sfumato" or smokiness in classic paintings?
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the artists observed blue light scattering caused by the reaction of hydrocarbons with ozone and water.
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Name the six criteria pollutants.
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PM (2.5 now but previously 10)
SOx NOx O3 CO lead |
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Why is NO2 called "the great absorber?"
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Is is the only primary pollutant to absorb light (hv) across the entire UV and visible spectrum. This created a great deal of energy causing it to be very reactive with oxygen to from ozone (a secondary pollutant). It is one of the major contributors to smog.
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Where does sulfur dioxide largely come from and what is it a precursor to?
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It comes primarily from fossil fuel burning and it is a precursor to acid rain.
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Is all ozone bad for the environment?
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No, stratospheric ozone is beneficial as it protects us from harmful UV radiation but tropospheric ozone can be related to many harmful health outcomes, most notably respiratory illness.
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Where do we typically see the largest numbers of ozone standard exceedances?
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In urban and metropolitan areas such as the greater LA area, Atlanta, greater Macon area, and metropolitan areas in Texas such as Dallas/Fort Worth and Austin.
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What size designations of PM are given and where can they each migrate into the respiratory system?
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Course (> 2.5 microns) can usually migrate into the nasal-pharyngeal region and into the trachea and bronchi
Fine (0.1 - 2.5 microns) can typically get lodged in the bronchial and alveolar regions Ultrafine (< 0.1 microns) can often pass from the alveolar regions of the lungs into the bloodstream |
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About how many hazardous air pollutants are targeted by the EPA?
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< 200
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Even though our GMP and lifestyles are improving and our aggregate criteria pollutant emissions are decreasing, why do we still have excess morbidity and mortality related to air pollution?
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About 1/2 of our population lives in areas where criteria pollutants exceed standards, especially ozone.
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In many developing countries, does indoor or outdoor air pollution contribute more to overall disability days?
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Indoor air pollution
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Name four greenhouse gases.
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CO2
Water vapor Methane Chlorofluorocarbons (CFCs) |
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How do greenhouse gases warm the earth?
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They absorb infrared radiation that is emitted by the Earth and re-emit it to the earth further warming it.
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How much of the energy that comes to the Earth from the sun is reflected back to the atmosphere?
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About 30%
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What do small energy increases in the Earth's atmosphere result in?
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Very large increases in the temperature on the surface of the planet
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Climate change causes us to see what?
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More variability in the Earth's weather resulting in extreme weather events (more droughts, more floods, more storms)
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Define climate change committment
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If we do nothing else to add to climate change, we have already committted ourselves to a certain level of change in temperature, sea level, and precipitation
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Define a scenario where climate change would have an impact on humans.
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Climate change causes a flood which causes a population to relocate; climate change can cause a drought which decreases the supply of food which causes starvation in a population; climate change causes a heat wave that increases mortality in the elderly, etc.
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What makes pesticides unique chemicals?
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They are lethal by design, we pay for the lethal chemicals, we purposefully introduce them into our environment, yet they still have a public health application.
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What are some health effects of pesticide exposures?
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Neurological deficits
Reproductive toxicants Death (from acute or chronic exposures) Endocrine modulating effects |
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In the case of Nemagon, describe the environmental justice issues related to the case.
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Known effects from exposure not shared with workers, poor population, jurisdiction of Nicaraguan cours, banned from US so moved to developing countries, warnings in English…
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What is the mode of action of organophosphate pesticides and how do they relate to nerve agents?
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They bind to the enzyme that breaks down the neurotransmitter acetylcholine (anti-cholinergic chemicals). They are considered "junior strength" nerve agents because they have the same mode of toxicity but do not bind quite as strongly.
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What were PCBs used for and how did they get into our environment?
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They were used as dielectric fluids in capacitors. They got into our environment from direct emissions from manufacture or from irresponsible disposal of capacitors or waste.
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What two rivers were contaminated with PCBs by GE and what steps have been taken to decontaminate them?
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The Hudson (NY) and Housatonic (MA) rivers. EPA has worked with GE on a plan to remove top sediments from the most contaminated areas of the rivers and dispose of them at a waste facility. Over 10 years was used to test and plan the decontamination. The first phase of the Hudson cleanup is completed (~ 6 miles of 200 miles of contaminated riverbeds) and the second phase (~40 miles) has begun. The Housatonic is largely completed. Both should be completed around 2015.
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Who are the most vulnerable for PCB exposure and why? How do we get exposed to PCBs today?
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Populations who eat subsistence diets (i.e., polar bears, seals, whale blubber). This often includes vulnerable or underserved populations like inuits. They are most highly exposed b/c of atmospheric redistribution of PCBs to colder climates in the Artic basin. Other areas widely contaminated include the Great Lakes. We are mostly exposed through the consumption of contaminated fish or meat and dairy products.
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What is the approximate half life of lead in blood, soft tissue, and bone?
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25 days, 28 days, and 27 years, respectively
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What is exposure?
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Exposure occurs when a chemical or agent comes in contact with a body envelope or interface such as skill, nasal membranes, and mouth
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What are the three primary routes of exposure?
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Ingestion
Dermal absorption Inhalation |
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Hazard =
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Hazard = Toxicity x Exposure
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What are the levels of hazard assessment?
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Tier I - Computer-based
Tier II - Bacteria or cells Tier III - Animals |
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What are the parts of risk management?
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Risk evaluation
Risk perception and communication Control of exposure Risk monitoring |
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What is risk communication?
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The purposeful exchange of information about the existence, nature, form, severity, or acceptability of risks in order to alert the public or decision makers or calm concerns about a small risk that may be perceived as severe
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What are psychosocial barriers in risk communication?
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Heuristics
Apathy Overconfidence Discomfort with probabilistic info Aversion to uncertainty Anchoring - persistence of long-held belief Outrage |
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What are natural sources of air pollution?
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Volcanoes
Forest fires Bioaerosols (pollens, fungal spores) |
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What are anthropogenic sources of air pollution?
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Power plants, metal refineries, incinerators
Pesticides Industrial leaks Cars, trucks, buses Planes |
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What does NAAQS stand for?
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National Ambient Air Quality Standards
Over 3000 substances have been measured in air, but we regulate emissions of < 20 |
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What are natural sources of ozone?
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Plants and trees (alkenes)
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What are the names for the harmful and beneficial ozones?
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Stratospheric ozone = beneficial
Tropospheric ozone = harmful |
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Climate change causes us to see what?
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Higher temperatures
Rising sea level More precipitation |
