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75 Cards in this Set
- Front
- Back
What does environmental health encompass?
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aspects of human health: quality of life, that are determined by physical, chemical, biological, social and psychosocial factors in the environment
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What is Who's definition of environmental Health?
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the theory and practice of asserting, correcting, controlling and preventing those factors in the environment that can potentially affect adversely the health of present and future generations
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What are different kinds of environmental hazards?
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physical, biological or chemical or cultural
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Physical Hazards: def
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occur naturally in our environment
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Examples of Physical hazards:
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earthquakes, volcanoes, fire, floods, droughts,
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How can we prevent physical hazards?
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We can't! but we can prepare and reduce the risk!
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What are chemical hazards?
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synthetic chemical such as pesticides, disinfectants, pharmaceuticals
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What are biological hazards? examples
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result from ecological interactions.
- viruses, bacteria, pathogens Infectious disease: other diseases that parasitize humans, fulfilling their ecological roles |
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Cultural hazards? examples
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result from the place we live, our socioeconomic status, occupation, behaviour choices
smoking drug us, diet and nutrition, crime, mode of transportation |
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Which is the easiest hazard to avoid?
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cultural because they can be controlled by our behaviours!
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Where are infectious diseases mostly found in relation to high death rates? why?
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15 mil people die a year
- half in developing countries - because developed countries have better hygiene, access to med, and money |
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Def Vector: ex?
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an organism that transfers pathogens to a host
ex: mosquito, transfer malaria to humans |
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Why are diseases spreading? (3)
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- our mobility (travel)
- evolving resistance to anti biotics - climate change will expand the range of diseases |
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Radon: Def
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a highly toxic, radioactive gas that is colourless and undetectable without specialized kits,
causes lung cancer |
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Lead poisoning
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- from water in lead pipes, lead based paint, toys
causes organ damage, learning problems, behaviour abnormalities, death |
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PBDEs
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comps, TVS, pastics, furniture,
cause: endocrine disruption, brain + nervous system |
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Toxicology: def
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study of the effects of poisonous substances on humans + other organisms
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Toxicity
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degree of harm a toxicant can cause
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what is toxicity analogous with
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pathogenicity, virulence
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toxicant
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any toxic agent
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What does environmental toxicology study?
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deals with toxic substance that are discharged in the environment
the health effects on humans, other animals and ecosystems - focuses on humans with animals as test subjects |
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Who published Silent Spring and what did it change?
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Rachel Carson, 1962
- presented the risks of DDT |
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What are different kinds of toxicants?
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Cacinogens
Mutagens teratogens allergens neurotoxins endocrine disruptors |
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Carinogens
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cause cancer
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Mutagens
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cause DNA mutations
can lead to severe problems |
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teratogens
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cause birth defects
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Allergens
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over activate the immune system
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Neurotoxins
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assault the nervous systme
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endocrine disrupter
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interfere with the endocrine system
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What do endocrine disrupters do? what do they cause?
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mimic horomones
Cause: -feminization of males - drop in sperm -testicular cancer -breast cancer rates rise -neurological problems |
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What does water have toxicants concentrating in it?
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- runoff carries toxins from large land areas to small volumes of surface water
- chemical leach into soil - chemical enter organisms though drinking or absorption (aquatic organisms are effecting pollution indicators) |
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Pesticide drift:
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airbourne transport of pesticides
- synthetic chemical contaminates are found globally |
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How does the persistence of toxicants vary? what effects it?
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some degrade quick others remain and persist for decades
- rates change: depending on sun exposure, moisture and temp |
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breakdown products:
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toxicant degrade into simpler products
May be more or less harmful than the original substance. DDT degrades into DDE, which is also highly persistent. |
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Bioaccumulation
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toxicants build up in animal tissues
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Biomagnification
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toxicants concentrate in top predators
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What is important to remember about the types of toxicants
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not all toxicants are synthetic!!!
Chemical toxicants also exist naturally and in our food. Don’t assume natural chemicals are all healthy and synthetic ones are all harmful. Some scientists feel that natural toxicants dwarf our intake of synthetic chemicals. However, others argue that natural substances are easily metabolized and excreted compared to synthetic chemicals which tend to persist and accumulate. |
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What is a useful tool for collecting information on the effect of toxicants
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wildlife studies, looking at museum data, may have stuff collected before synthetic chemicals were used!
- can compare wild to controlled labs |
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Case histories
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the process of observation and analysis of individual patients
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Epidememiology
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large scale comparisons among groups of people, generally for a long period of time
- studies between exposed vs. unexposed people last for years |
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Manipulative experiments
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using animals, lab exposes subjects to toxicant and establish causation
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Dose
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amount of toxicant received
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Response
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type or magnitude of negative effects of the animal
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Dose- response curve
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the plot of dose given against response
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LD50/ED50:
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LD50/ED50= the amount of toxicant required to kill (affect) 50% of the subjects.
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Threshold
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the dose level where certain responses occur
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What are the three curves for dose response analysis?
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linear,
dose response curve with threshold] - u-shaped dose response curve |
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Why do people respond different to hazards?
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- affected by genetics, surrounding
- people w/ poor health - sensitivity that varies with age, sex, weight |
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Standard set by health canada are only valid for who?
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the average adult
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acute exposure:
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high exposure
- short period of time - ingestion, oil spills, nucleur accident |
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Chronic exposure
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low exposure,
- long period of time - affects organs gradually, |
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Which is easier to regocnize?
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acute, easier
chronis: hard to detect + diagnose, cause and effect may not be easily apparent |
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Synergistic effects:
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interactive impacts that are more than or different from the simple sum of their constituent effect
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Pesticide drift:
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airbourne transport of pesticides
- synthetic chemical contaminates are found globally |
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How does the persistence of toxicants vary? what effects it?
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some degrade quick others remain and persist for decades
- rates change: depending on sun exposure, moisture and temp |
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breakdown products:
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toxicant degrade into simpler products
May be more or less harmful than the original substance. DDT degrades into DDE, which is also highly persistent. |
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Bioacumulation
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when toxicant build up in animal tissues
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Explain the fact that all toxicants are not synthetic!
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- chemical toxicant also exist naturally in our food
- natural toxicants probably drarf our intake of synthetic ones - but natural ones my be more metabolized and excreted compared to synthetics |
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Explain how using wildlife studies is a tool for studying toxicants?
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musuems do collections that provide data from times before synthetics
- measurements from animals in the wild can be compared to controlled - concpicuous mortality events can trigger research |
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Whats an example of wildlife research?
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1998 sea otters diet from toxoplasma from sewage run off containing cat litter
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case studies
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the process of observation and analysis of individual patients
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epidemiology
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large scale comparisons amount groups of people, generally for a long period of time
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manipulative experiments
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lab experiments that expose subject to toxicants to establish causation
- animals often used as modles |
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dose
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amount of toxicant the test animal recieves
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response
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the type or magnitude of negative effects of the animal
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dose-response curve:
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the plot of dose given against response
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LD 50/ ED 50
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the amount of toxicant required to kill 50% of the subjects
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Threshold:
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the dose level where certain responses occur
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Why do people vary in their response to hazards?
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Affected by genetics, surroundings, etc.
People in poor health are more sensitive. Sensitivity also varies with sex, age, and weight. Fetuses, infants, and young children are more sensitive. |
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Acute exposure =
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high exposure for short periods of time to a hazard.
Easy to recognize. Stem from discrete events: ingestion, oil spills, nuclear accident. |
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Chronic exposure =
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low exposure for long periods of time to a hazard.
Hard to detect and diagnose. Affects organs gradually: lung cancer, liver damage. Cause and effect may not be easily apparent |
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Synergistic effects =
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= interactive impacts that are more than or different from the simple sum of their constituent effects.
Mixed toxicants can sum, cancel out, or multiply each other’s effects. New impacts may arise from mixing toxicants. |
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Toxicology:
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“Studies how environmental exposures lead to specific health outcomes, generally in animals, as a means to understand possible health outcomes in humans”.
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Environmental epidemiology:
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“Studies the relationship between environmental exposures (including exposure to chemicals, radiation, microbiological agents, etc.) and human health”.
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Exposure science:
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“Studies human exposure to environmental contaminants by both identifying and quantifying exposures.
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