MIEH 300- FINAL EXAM

what is the environment?

- everything that is external to the human that can influence the health of the population

-physical, biological, social, cultural

what are the divisions of environmental science?

1. humans

2. natural resources

3. pollution

what is the ecological model of population health?

-proposes that the determinants of health interact and are interlinked

what is environmental health?

-the study of how the environment affects human health

-protects against the effects of environmental hazards that can adversely affect health / ecological balances for human health

- encompasses the assessment and control of those environmental factors that can potentially affect health

-targeted toward preventing disease and creating health-supportive environments

what are constitutional factors that affect the scope of health?

1. genetic traits and social/ behavioral hazards: chemical, biological, and physical hazards

ex: women's genetic makeup and exposure to man-made chemicals = possible risk of getting breast cancer

what are the 5 disciplines of environmental health?

1. environmental epidemiology

2. toxicology

3. exposure science

4.environmental engineering

5. environmental law

what is environmental epidemiology?

-studies the relationship between environmental exposures and human health

-ex: exposure to chemicals or radiation

what is toxicology?

-studies how environmental exposures lead to specific health outcomes generally in animals, to understand possible health outcomes in humasn

what is exposure science?

-studies human exposure to environmental contaminants by both identifying and quantifying exposures

-supports environmental epidemiology by describing environmental exposures that can lead to a health outcome

what is environmental engineering?

-applies scientific and engineering principles for protection of human populations from the effects of adverse environmental factors

-protection of environments from potentially deleterious effects of natural nad human activities

-general improvement of environmental quality

what is environmental law?

-includes the network of treaties, statues, regulations, common and customary laws addressing the effects of human activity on the natural environment

what is the one health approach?

-healthy ecosystems

-healthy humans

-healthy animals

-an interdisciplinary approach used to evaluate the connections between humans, animals and the envrionemnt

what are vulnerable subgroups of the population?

-more likely to be affected by environmental hazards

-ex: young kids + older adults

-immune systems are still developing

how does climate change effect the developing world?

-pursuit of natural resources in the developing country causes unsanitary food, water contamination, and air pollution

-ex: Asia: decrease forest land= runoff

what is environmental risk transition?

-characterize changes in environmental risk that happened as a consequence of economic development in less developed regions of the world

-poor societies

what are population dynamics?

-ever-changing interrelationships among the set of variables that influence the demographic makeup of populations as well as the variables that influence the growth & decline of population sizes

-ex: fertility (total fertility rate) , death rates (burden of. disease, life expectancy, and disability-adjusted life years), and migration

what is the demographic transition?

alteration over time in a population fertility, mortality, and makeup

what is the epidemiologic transition?

-shift from deaths by communicable diseases to death by chronic diseases

-accompanies the demographic transition

what is a megacity?

-urbanized area with 10 million + people

-ex: Tokyo, Mexico City, LA, NYC

what is carrying capacity?

-max # of individuals that can be supported sustainability by an environment

what is food insecurity?

-supplies of wholesome foods are uncertain or have limited availability

what are the ancient origins of environmental health?

-the idea that the environment could have an impact on comfort and well-being (the core idea of environmental health)

-the elements can be hard (ancestors lived in the caves for safety)

-food safety: preservation and dietary restrictions

-clean water: Romans developed infrastructure for maintaining public health

-clean air: Egyptians created vents to remove smoke from their kitchens

what was the westward expansion of 1810s?

-government promoted settlement in the midwest

-gov gave out millions of acres to citizens and railroad companies to encourage settlers, entrepreneurs, and land speculators to move west

what was the exploitation of the westward expansion?

-early centuries in the US had widespread environmental exploitation

-it was thought that land, timber, wildlife, rich soil, and clean water were all cheap and inexhaustible

what was the frontier attitude?

a desire to conquer and exploit nature as quickly as possible

how were the one health affects of the westward exploitation?

-beavers: killed for their resources

-prey and predator animals impacted

-buffalo population decreased greatly (mil to hund)

what were the efforts to protect forest in the 1800s?

1. Yellowstone park (1872): worlds first national park after Montana explorers reported the natural beauty there

2. american forestry association (1875): influenced public opinion against the wholesale destruction of America's forest

3. Yosemite national park bill (1890): established Yosemite and Sequoia National Parks in California.

who is John Muir?

-naturalist and writer

-founded the sierra club: a national conservation organization that is still active on a range of environmental issues

what efforts have their been to protect national monuments?

1. Antiquities Act ( 1906): authorized the president to set aside certain sites that had scientific, historical, or prehistoric importance. (ex: badlands in South Dakota)

2. National Park Service (1916): US Army was managing 13 national parks and 20 national monuments. Now, the national park service manages 63 national parks and 85 national.

-Woodrow Wilson established this

why was protecting national monuments and forest important?

1. inspiration: beautiful, fishing, hiking, bird watching]

2. revenue: eco-tourism (millions visit)

3. utilitarian benefits & ecosystem services: forested watersheds provide cities clean drinking water and a buffer against floods

4. refuges for biodiversity: species are contained in this area and we dont want to decrease that.

-rising temps cause some species to migrate

-some species get trapped in parks

what are some historically significant environmental health catastrophes?

1. London Killer Smog (1952)

2. Minamata Bay, japan (1930s-1960s)

3. Cuyahoga River fire

4. santa barbara oil spill (1969)

what was the London Killer smog?

-1952

-caused by coal burning and weather conditions

-4000-12000 deaths

-prompted Clean Air Act of 1956

-ONE HEALTH: cattle were suffocating and had tp be euthanized

what is the Minamata Bay, Japan?

-waste discharged from a chemical plant

-caused methylmercury poisoning in people who ate contaminated fish and shellfish

-symptoms: sensory disturbances, tremors, brain lesions, coma, and death

- was detected late

what was the Cuyahoga River Fire?

-Cuyahoga river during the 20th century was one of the most polluted rivers in the US

-1952 fire caused over 1 million in damages (the worst fire)

-1969 fire: helped spur an avalanche of water pollution control activities resulting in the Clean Water Act and the creation of the EPA

what was the Santa Barbara Oil spill?

-1969

-largest oil spill in US waters at this time

what are the one health affect of oil spills?

-obvious impacts on animals and the environment

-water and soil contaminated then humans drink or swim in it

-now using hydrophobic wax beads to clean up oil spills

what was the beginning of the modern movement of 1960s?

-there was public concern about pollution and resource quality began to increase (due to marine biologist RACHEL CARSON)

-Carson: wrote about the interrelationships among living and the environment. Her most famous work was Silent Spring: wrote against the use of pesticides

-Paul Ehrlich: published the population bomb that stated there would be unavoidable population damage to support such a large population (overpopulation)

how did earth day start?

-before 1970: environmentalists were heard by the Sierra Club and the National Wildlife Federation

-The environmental movement started the year after the Santa Barbara spill in 1970

-Environmentalists gathered to raise concern and that became the 1rst Earth Day

-many participated in this with rallies

what environmental movements are there today?

1. Earth Day: planet vs plastics: 60% reduction in plastics by 2040

- need to act boldly, innovate and implement

- sustainability is the path to prosperity

-ex: clean energy jobs ( above wage, outpace fossil fuels)

still work to be done

what is epidemiology?

-concerned with the study of the distribution and determinants of health and diseases, morbidity, injuries, disability, and mortality in populations

-especially concerned with causality

how does epidemiology observe to study disease occurrence?

-who gets a disease

-where and when the disease occurs

- all to intervene and prevent disease from occurring to determine WHY the disease occurs

what are the 2 main goals of epidemiology?

intervening and preventing disease occurrence

what are exposures in environmental epidemiology?

-outside the control of the individual

-may be considered involuntary

-stem from abient and occupational environments

what are the 4 topics of study in environmental epidemiology?

1. air pollution

2. chemicals

3. climate change

4. water pollution

how is air pollution studied in environmental epidemiology?

-associated with increased urbanization

-adverse effects on vulnerable populations (kids & elderly)

-adverse effects on minority and llow income populations living near industrial facilities and power plants

how are chemicals studied in environmental epidemiology?

-effects of pesticides, asbestos, lead, and mercury on cancer risk, adverse reproductive outcomes, nervous system impacts

how is climate change studied in environmental epidemiology?

-document extreme climate events

-rising temperatures contributes to these issues ( drought, fires, rising temps, floods)

how is water pollution studied in environmental epidemiology?

-adverse effects from urban runoff, compromised pipes, as well as water rights and access

how does epidemiology contribute to environmental health?

-they focus on an entire population (could just be 1 city) and the use of descriptive and analytic methodologies

what kind of data is descriptive and analytic methodologies?

-observational data: b/c experimental isn't ethical

what are clinical observations used for?

-to help identify and diagnose individual patients who are afflicted by environmental hazards

-ex: PH department receives complaints of diseases-> case reports are collated to develop a hypothesis-> broader investigation of the entire community occurs -> the findings aid in controlling exposures and developing health policies

how is John Snow an historic example in environmental health epidemiology?

-considered a natural experiment (ex: some places in US prevent smoking outside to prevent 2nd hand smoke)

-he was skeptical of miasma theory (diseases were caused by bad air)

- helped link the Cholera outbreak in London 1850s to contaminated water from the Thames River

-his work is considered the founding event of the science of epidemiology

who was Sir Percivall Pott?

- a London Surgeon who was thought to be the first individual to describe an environmental cause of cancer (first clear description)

-chimney sweeps had a higher incidence of scrotal cancer than other occupants due to contact with soot

-published a book titled: Chirurgical Observations Relative to the Cataract

what are the 3 requirements for a successful environmental epidemiology study?

1. direct and accurate estimates of the exposures experienced by individual members of the study population

2. direct and accurate determination of the disease status of individual members of the study population

3. appropriate statistical summarization and analysis of the individual data pertaining to disease and exposure

what are the 2 classes of epidemiological studies?

descriptive and analytical

what is a descriptive study?

-depiction of the occurrence of disease in populations according to classification by person, place, and time variables

-observing

-case reports, case series, and descriptive surveys

what is the connection between William Farr and descriptive studies?

-metal miners had higher mortality from all causes than the general population

what is disease clustering?

-closely grouped series of events/ cases of a disease with well-defined patterns in relation to a time/place

-suggest common exposures

-ex: Texas sharpshooter effect (occurrence of something in same place over time)

what are analytical studies?

-examines causal (etiologic) hypothesis regarding the association between exposures and health conditions

-examining

-observational and experimental studies

what are observational studies?

cross-sectional

case control

cohort

what are experimental studies/

lab trials

field trials

what is an interventional study?

- a type of experimental study that causes intentional change

2 types

1. randomized/ clinical: test efficacy of new meds

2. quasi- experimental: individual subjects arent randomized ( community trial)

what is the goal of study design methodology?

study goal is to determine an association between an exposure and a disease or other health outcomes

how many observational study designs are there?

1. case- series

2. cross-sectional

3. ecological

4. case- control

5. cohort : retrospective (looking at data) or prospective (over time)

what is a classic example of an experimental study?

-subjects are randomly assigned to either a treatment group or control group

-exposure: something new

-use these studies to test new medications

why are there no experimental studies in environmental health?

-unethical to randomize individuals into groups with different environmental exposures/ factors

-difficult to properly randomize

-community intervention trials can be used in environmental epidemiology, but randomization is rarely used

why are community intervention trials rarely used?

it heavily dilutes the benefits of randomization

why is randomization important?

-eliminates the selection bias

-balances the groups with respect to many known or unknown confounding or prognostic variables

-forms the basis for statistical tests

what is recall bias?

-cases may remember an exposure more clearly than controls

-can reduce the reliability of exposure information gathered from control groups

what is selection bias?

-relationship between exposure and disease in the study population is NOT REPRESENTATIVE of the true relation between exposure and disease in the general population because the investigator has selected the study population in a non-representative way

-ex: healthy worker effect

what is the healthy worker effect?

-population is different than general population

-ex: Military (less clinically ill and have fewer kids)

what is confounding?

-distortion of the exposure-disease relationship by a third variable that is associated both with the exposure and with disease

-ex: miners and lung cancer

-confounder can mess with data (cant say for sure cause/ effect)

why do we use measures of disease frequency?

to describe the occurrence of disease, morbidity, and mortality in populations

what is prevalence?

-number of existing cases of, or deaths from, a disease or health condition in a population at some designated time

-reveals a snapshot of disease prevalence in the population

what is point prevalence?

-all cases of, or deaths from, a disease or health condition that exist at a particular point in time relative to a specific population from which the cases are derived

-one specific date/ time

what are the functions of prevalence?

1. assess variation in the occurrence of disease

2. aid in the development of the etiologic hypothesis

what is incidence?

occurrence of new disease or mortality within a defined period of observation in a specified populaiton

what is incidence rate?

rate at which new events occur within the population

what is case fatality rate?

-the measure of the lethality of the disease

what is an environmental epidemiology study?

- a study that will determine if a disease or health outcome observed in a population is linked to an environmental factor

-ex: is lung cancer mortality higher in towns with higher concentrations of " smokestack" industries, such as car manufactures and steel factories

what are the main criteria that must be in place to establish causality?

1. the exposure came BEFORE the disease ( temporality)

2. the observed relationship between exposure and disease did not happen by chance (specificity)

3. there is nothing else that accounts for the relationship between exposure and disease ( no confounding)

what are the Bradford Hill criteria?

- 9 criteria that must be in place in order to determine if a causal relationship exists between exposure and disease

1. strength

2. consistency

3. specificity

4. temporality

5. biological gradient

6. plausibility

7. coherence

what is a case series?

- gathers information over time from patients who share disease or exposure in common

-one of the weakest study types for making causal assertions

-results of a case-series study are typically used as a starting point for developing hypotheses for more complex investigations

what are the pros and cons of a case series?

pros

- more cost-efficient than larger studies

-short time to results and publication

-used to determine if larger studies are needed

cons

-limited data

-small study population may not be representative

-difficult to replicate

what is a cross-sectional study?

-examines the relationship between diseases and other variables of interest as they exist in a defined population at one particular time

-type of prevalence study: distribution of disease and exposure are determined

-looking at individual people: a lot of participants

-Pro: used to formulate a hypothesis that can be followed up by an analytic study

what is an ecologic study?

-explore the statistical connection between disease and estimated exposures in population groups rather than individuals

-units of analysis: populations or groups of people (not individuals)

-they combine data from vital records, hospitals, or disease registries

-can provide clues about causal associations but results can be difficult to interpret

-uses the relative ratio

-pro: can get more information

what are case-control studies?

-subjects who participate in the study are defined based on the presence or absence of an outcome of interest

-cases: have the outcome

-control: those who dont have the outcome

-researchers look back in time to learn exposures to risk factor comparing the frequency of the exposure in the case group to the control group

-cases and controls are matches according to sex, age, race, or other variables

what are the pros and cons of case- control studies?

pro

-more complete exposure data

-eliminates bias

-can examine many exposures

con

-examine only 1 outcome

what are cohort study?

-classify subjects according to their exposure to a factor of interest and then observe them over time to document the occurrence of new cases( incidence) of a disease or other health events

- a type of longitudinal study design: subjects are followed over an extended period of time

what are the pros and cons of a cohort study?

pro

-evaluate many outcomes

cons

- evaluate few exposures

what are the limitations in detecting disease and measuring exposure?

1. Long and variable latency periods between exposure and disease diagnosis

2. etiologic non-specificity of disease clinical features

3. probably low-dose levels in most settings

what is a latency period?

-the time interval between initial exposure to a disease-causing agent and the appearance of a disease or it's manifestations in the host

-long latency may reduce the epidemiologists ability to ascertain definitively the outcomes of exposure

-easier when the latency period is smaller

ex: hepatitis: long latency food borne: short latency

what are etiologic non-specificity of disease clinical features?

-many disease conditions thought to be related to environmental exposures are influenced by many factors

-any environmental exposure probably will not be associated with a specific outcoem

why are environmental exposures probably not associated with a specific outcome?

-we are exposed to hundreds of chemicals in the environment due to cumulative exposure

ex: cancer and respiratory disease

what is the probable low dose levels in most settings?

1. low-level environmental exposures are difficult to study because

-researchers cant apply lab methods

-cant determine the exact exposure

-cant determine if exposure to 1 agent occurred

2. exposure measurements in environmental epidemiology include

-samples of toxic fumes in plant

-ozone readings in the community

-radiation

what is toxicology?

- the science of poisons

-the study of the adverse effects of chemical, physical, or biological agents on livining organisms and the ecosystem, including the prevention and amelioration of such adverse effects

why is environmental health concerned with toxicology?

-more than 80,000 chemicals are used in the US

-want to know the effects of these chemicals and at what level of exposure do they become hazardous to humans

what is an exposure?

proximity and/ or contact with a source of a disease agent in a manner that effectively transmission of the agent or harmful effects of agent that may occur

what is the relationship between toxicology and epidemiology?

-work together to assess the available scientific evidence relating to potential environmental disease- causing hazards

-relevant evidence arises from toxicologic and epidemiological investigations and reflects knowledge at many levels

what is the difference between in vivo and in vitro?

1. in vivo: in living organisms (ex: using rats and guinea pigs)

2. in vitro: in glass (ex: cell cultures)

- these are less destruction but have limitations because not everything can be tested