Exam 1 Flashcards
How is the environment related to human health
environment is intimately connected with human health, illness, and mortality
what percentage of the worlds deaths are caused by environmental factors
in the 1990s: 40%
in 2012: 1/4
list examples of today’s environmental health threats
- trash on beaches
- hazardous wastes leaching from disposal sites
- continuing air pollution
- exposure to toxic chemicals
- destruction of land/deforestation
- global warming
what are the goals of the Healthy People 2020
- improve environmental quality
- outdoor air quality
- water quality
- toxics and wastes
- healthy homes and healthy communities
- infrastructure and surveillance
- global environmental health
what is the AQI
Air Quality Index
- values 0-50: green - good air quality
- values 51-100: yellow- moderate air quality
- values 101-150: orange- unhealthy for sensitive groups
- values 151-200: red- unhealthy
- values: 201-300: purple - very unhealthy
- values: 301+: maroon- hazardous
What 5 major pollutants is AQI based on
O3, PM, CO, SO2, and NO2
who does poor environmental quality have the greatest impact to
people whose health status is already at risk
Who are vulnerable subgroups of the population
elderly people with disabilities and chronic disease, pregnant women, and children
children are vulnerable because their immune system is still developing and are not fully capable of responding to environmental toxins
What are the 3 P’s
Pollution
Population
Poverty
these are principal determinants of health worldwide (Dr. Warren Winkelstein)
how are the three P’s interrelated
population growth is associated with poverty, and both poverty and population growth are associated with pollution.
Pollution and population growth are often associated with adverse economic circumstances (poverty) and, therefore, are also closely connected with environmental health
Give an example of the impact of pollution
effects of fuel combustion (air pollution) on global environmental health
Combustion of fossil fuels –> dispersment of greenhouse gases into atmosphere –> global warming –> change in distribution of insect vectors —> impact on global environmental health
what is the threat of over population
overpopulation in developing nations could cause urban crowding, food shortage, malnutrition, and a series of health problems
- human population might exceed the carrying capacity of the planet
- world population might reach 10 billion during 21st century
why does poverty impact environmental health
- poverty is linked closely to population growth and it is one of the well recognized determinants of adverse health outcomes
- wealthy nations can provide better access to medical care and are capable to financing various pollution controls
What is the environmental risk transition
the change in environmental risks that happen as a consequence of economic development in the less-developed regions of the world
environmental health issues in developing countries
Factors: unclean air, dirty water, bad food, and poor medicine
Health Problems: diarrhea, acute respiratory disease, malaria, malnutrition, tuberculosis, etc.
Local and Immediate
environmental health issues in developed countries
Factors: long-term, long-range pollutants (ex: acid rain, ozone depleting chemicals, ultrafine particles, and greenhouse gas emissions)
Health Problems: cancer, cardiovascular diseases, diabetes, and neuropsychiatric effects
Global and Delayed
What factors contribute to population growth
- increases in fertility and reductions in mortality
- current population: 8 billion
- predicted population in 2050: 10 billlion
order of predicted most populated countries in 2050: India, China, USA
What are population dynamics
Ever-changing interrelationships among variables that influence the demographic makeup of populations and variables that influence the growth and decline of population sizes
the three key factors of population dynamics
Fertility
Mortality
Migration
Increases in fertility and reductions in mortality are the primary reasons contributing to population growth
What is the total fertility rate (TFR)
- total number of children a women has given birth to by the end of her childbearing period
what is the current US fertility rate
2.0 births per women (in 2012)
what is the estimated natural population replacement rate
2.1
Countries with TFR below the replacement rate
US, Canada, Japan, South Korea, Thailand, China, and European countries
Countries with TFR of 4.0 births per woman
South Asian, Latin American, and African Countries
What has contributed to the decrease in mortality
public health improvements, famine control, and increased availability of drugs, vaccines, and medical treatments
How is migration impacting population growth
- by 2050 US population will grow by another 100 million and about 1/3 of the growth will be from migration
- 1 billion of the worlds residents are migrants
Demographic Transition
alterations over time in a population’s fertility, mortality, and make-up
Demographic transition stage 1
high fertility rate, high mortality rate, small population (mostly young population). Chart looks like a curved triangle
- rapid population growth
Demographic transition stage 2
high fertility rate, low mortality rate, rapid increase in population.
Chart looks like strong triangle
includes US, Australia, and Canada
- slow population growth
Demographic transition stage 3
low fertility rate, low mortality rate, population growth becomes slow or stops
- zero growth
demographic transition stage 4
- negative growth
- Germany, Bulgaria, Sweden, and Taiwan
Epidemiologic transition
shift in the pattern of morbidity and mortality
- Before shift: causes of morbidity and mortality were primarily related to infectious and communicable diseases (ex: cholera, HIV, TB, etc. )
- After shift: causes are associated with chronic degenerative diseases (cardiovascular diseases, cancer, neuropsychiatric conditions)
consequences of population increase
Urbanization
Overtaxing carrying capacity
Food insecurity and Famine
Loss of biodiversity
consequences of urbanization
cause significant demands for energy, water, and air quality controls, construction materials, food, sewage processing, and solid waste disposal
consequences of overtaxing carrying capacity
available resources are exhausted due to population increase
consequences of food insecurity/famine
supplies of wholesome foods are uncertain or may have limited availability
consequences of loss of biodiversity
danger to food production due to eradication of healthful plants and insects
How is infectious disease epidemics a possible consequence of crowding
virus mutation enabling human to human transmission
what is Ecological system (ecosystem)
dynamic complex of plant, animal, and microorganism communities, adn the the nonliving environment interacting as a functional unit
what is the environment
the complex of physical, chemical, and biotic factors… that act upon an organism or an ecological community and ultimately determine its form and survival
what is environmental health
addresses all the physical, chemical, and biological factors external to the person, and all the related factors impacting behaviors. It encompasses the assessment and control of those environmental factors that can potentially affect health. It is targeted towards preventing disease and creating health-supportive environments (WHO)
Hippocrates role of environment in disease
460-370 BC
- greek philospher
- “father of medicine”
- developed the concept of the relationship between environmental factors and human health, and emphasizes influence of the environment on people’s health
- promoted doctrine of maintaining equilibrium among the bodys four humors (yellow bile, black bile, phlegm, and blood) in his work titled On Airs, Waters, and Places
Paracelsus role in environmental health
1493-1541
- swiss physician, alchemist, and philosopher
- “father of toxicology”
- “sola dosis facit venenum” - the dose makes the poison
- toxicology is the core environmental risk assessment because toxicity is the capacity of a substance/pollutant to produce serious bodily injury or death
- contributed to the concept of the dose response relationship and the notion of target organ specificity of chemicals
Significance of Rachel Carson in environmental health
Rachel Carson (1907-1964) published Silent Spring (1962)
After Silent Spring was published public concern about the effects of technology on the environment significantly increased. As a result, the 1970s are notable for the large number of important federal regulatory laws that are applicable to the environment (EPA and OSHA)
Historical background on environmental and occupational health
- occupational health is a subset of environmental health
- Environmental health: focus on the adverse health effects of hazardous substances in the environment on the general public, including vulnerable populations
- Occupational Health: focus on the adverse effects of hazardous substances in the workplace on the workers
- occupational health is called industrial hygiene in the US and occupational health professionals are called industrial hygienists
Role of a toxicologist
- specializes in the effects of toxic chemicals on the environment and living creatures
- toxicologists investigate the effects of chemicals on the human health
- knowledge in biology, physiology, and chemistry are needed
- jobs include: gov labs, academic labs, or company labs
Role of environmental health inspector
- monitors and enforces gov regulations. Includes: pollution inspector, noise inspector, and water quality inspector. Food inspector. Involved with cleanliness and safety of foods consumed by the public
- knowledge in chemistry, physics, and nutrition
Role of Vector Control specialist
enforces various public health laws, sanitary codes, and regulations related to the spread of disease by vectors. Conduct basic research on the risks associated with exposures to certain hazards and conduct statistical analyses of impact by humans.
- researcher/research analyst with knowledge of biology, ecology, and infectious disease
Role of environmental Scientist/Risk assessor
- investigate hazards in the environment. Estimate the hazard of exposure and health risks. Develop procedures for abatement of hazards or reduce exposure. Conducts health education programs
- Require specific knowledge in environmental health
Role of Environmental lawyer
- provides input to government agencies. Helps formulate policy. Involved in litigation concerning environmental health problems
- requires comprhensive knowledge in environmental health and law
Role of a Biostatistician
research
Role of occupational health specialist (industrial hygienist)
- responsible for anticipation, recognition, evaluation, and control work place hazards to protect workers health
What is epidemiology
discipline focused on studying the distribution and factors influencing health, etc. within populations
- three major ways to identify the causality between hazards and adverse health effects: epi studies, toxicological animal studies, and human studies
what is environmental epidemiology
study of diseases and health conditions linked to environmental factors
- connect certain environmental factors with cancer and other adverse health outcomes
what are the essentials of environmental epidemiology
- exposure to the environmental hazards are usually involuntary
- typically focuses on involuntary exposures among vulnerable groups
contributions of epidemiology to environmental health
- concern with population
- use of observational data
- methodology for study designs
- two classes of epidemiologic studies
epidemiology concern with population
- studies health issues in a population
- many hazardous exposures occur at the population level not individual
- population medicine
- research example: association between lung cancer mortality and population in areas with higher conc. of smokestack industries
epidemiology concern with observational data
- observational study techniques are appropriate for environmental health research with no ethical issues
- epi is primarily observational science
- takes advantage of naturally occurring situations to study the occurrence of disease
epidemiology methodology for study designs
- experimental design
- Quasi-experimental study
- Observational study design: cross sectional, ecologic, case control
what are the two classes of epidemiologic studies
Descriptive study
Analytic study:
- observational and interventional
descriptive study
- aiming to delineate the patterns and manner in which disease occurs in populations
- depicts occurrence of disease in populations according to classification by person, place, and time variables
- research examples: patterns of tobacco use among adolescents in high school, maternal mortality rate in certain population over last decade
Analytic study
- examine causal (etiologic) hypothesis regarding the association between exposures and health outcomes
- proposes and evaluates causal models that employ both exposure and outcome variables for the association between exposure and health outcomes
- research examples: association between air pollution exposure and the risk of cardiovascular disease
Exposure variables
contact route and time of toxic substance, substance toxicity, type of hazardous agent, etc
Outcome variables
specific disease, cause of mortality, health condition, etc.
difference between prevalence and point prevalence
point prevalence refers to a particular point in time
- this data contributes to accomplishment of two primary functions of of descriptive epi: assess variation, aid in developmental of etiologic hypothesis
prevalence
- snapshot of disease occurrence in population
- describes the distribution of health outcomes
- number of existing cases/deaths in a population at a designated time frame
- research example: prevalence of obesity in rural america during covid-19 lockdown period
incidence
occurrence of NEW disease or mortality within a defined period of observation
- number in the population who are able to develop the disease are the at risk population
- research examples: trends in the incidence of lung cancer among smokers
Incidence rate
- the RATE the new cases occur in the population
(# new cases)/(avg. population at risk) - these measures are central to to the study of causal mechanism with regard to how exposure affect health outcomes and measures
- research examples: incidence rate of depression in post-disaster population
Case Fatality Rate (CFR)
- measure of the lethality of a disease
- number of deaths due to a specific disease within the specific time period divided by the number of cases of that disease during that time
- research example: impact of early intervention on the case fatality rate of stroke in a regional stroke center
Sir Percival Pott
1714- 1788
- Surgeon in london
- first individual to describe the environmental cause of cancer
- observed that chimney sweeps had a high incidence of scrotal cancer due to contact with soot
- established occupational hygiene control measure: chimney sweepers are to bathe once a week
John Snow
1813-1858
- english anesthesiologist
- linked cholera outbreak in london to contaminated water from the thames river in 1849
- his methodology was “natural experiment”
Intervention studies and observational studies
Intervention Studies:
- Experimental studies
- quasi- experimental studies
Observational Studies:
- case series studies
- cross-sectional studies
- ecologic studies
- case control studies
- cohort studies
intervention study
investigation involving intentional change in some aspect of the status of the subject
- clinical trials
- quasi experiments
Clinical trials
- randomized control trials
- experimental design in which there is manipulation of an exposure variable and a random assignment of subjects to either a treatment group or control group
Quasi-experiments
community trials
- experimental design in which manipulation of an exposure variable occurs, but individual subjects are not randomly allocated to study the conditions
Observation study
better strategy for environmental epidemiology to study the effect of environmental exposures when dealing with the human population
- most of the studies on health outcomes associated with the environment are observational
Case Series
- information about patients who share a disease in common is gathered overtime
- weak for making causal assertions. Info collected can be useful for developing hypothesis for further study
cross-sectional studies
- examines relationship between disease and other variables of interest as they exist in a defined population at one particular time
- type of prevalence study in which the distribution of disease and exposure are determined
- may be used to formulate a hypothesis that can be followed up in analytic studies
Ecologic studies
- units of analysis are populations or groups of people rather than individuals
- info collected may provide preliminary data for more carefully and rigorously designed analytic studies
case-control studies
- commonly used in environmental epi research for studying the association between exposure and outcome
- cases are recruited subjects who already have the outcome or disease of interest
- exposure to a factor is determined retrospectively
- one way to determine past exposure is to interview cases and controls regarding their exposure history
- advantage: can examine many potential exposures
- disadvantage: can only examine one or a few outcomes
- measure of association used is odds ratio (OR)
Odds Ratio
- measure of exposure and outcome
- used in case control studies for hypothesis testing
- ratio of odds in favor of exposure among case to the odds in favor of exposure among non cases
- OR>1 suggests a POSITIVE association between exposures and disease or other outcome
cohort studies
- classifies subjects according to their exposure to the thing of interest and then observes them over time to document the occurence of new cases of disease or other health events
- longitudinal design
- allows epidemiologists to evaluate many different outomes but only a few exposures
- measure of association is relative risk
relative risk
- ratio of the incidence rate of a disease or outcome in an exposed group to incidence rate of the disease or condition in the non exposed group
- used in cohort studies for hypothesis testing
- RR>1 indicates the risk of disease is greater in the exposed group than in the nonexposed group (positive association between exposure and the outcome)
- RR<1 indicates a probable protective effect
epidemiologic triangle
- provides framework for investigating the causality of environmental health problems and viewing hypothesized relationships
- includes three majors factors: agent, host, and environment
agent
a physical, chemical, or biological factor whose presence, xs presence, or relative absence is essential for the occurrence of a disease
host
a person or other living animal that affords subsistence or lodgment to an infectious agent under natural conditions
environment (epi triangle)
the domain in which disease-causing agents may exist, survive, or originate (consists of all that which is external to the individual human host)
causality
- criteria must be taken into account in the assessment of causal association between an agent factor and and a disease
Hill’s Criteria of Causality: - strength: strong association must be found
- consistency: association should be observed repeatedly
- specificity: must be constrained to a particular disease exposure relationship
- temporality: must observe the cause before the effect
- biological gradient: must have a biological gradient (dose-response curve)
- plausibility: must be biologically plausible from the standpoint of contemporary biological knowledge
- coherence: the cause and effect interpretation of the data should not conflict with the known fact of the nature history and biology of the disease
Bias
systematic deviation of results or inferences from the truth
- error in the conception and design of a study leading to results or conclusions that are systematically different than the truth
- examples could be related to: study design, data collection, data analysis, and interpretation of findigs
recall bias
- cases may remember an exposure more clearly than controls
- reduces the reliability of exposure information gathered from control groups
Selection bias
- arises from the procedure used to select individuals into the study
- causes systematic difference in characteristics between participants and non participants in research
- example: healthy worker effect
healthy worker effect
- employed populations tend to have a lower mortality experience than the general population
- can introduce selection bias into environmental and occupational morality studies
- cause: people whose life expectancy is shortened by disease are less likely to be employed than healthy persons
- causes reduced or attenuated measure of health effect to be observed for an exposure that induces morbidity or mortality
- likely to be stronger for non-malignant causes of mortality
confounding factors
distortion of a measure of the effect of an exposure on an outcome due to the association of the exposure with other factors that influence the occurrence of the outcome
- associated with disease risk and can produce different distributions of outcomes in the exposure groups than in the comparison group
- existed of these variables can lead to invalid conclusions from a study
Requirements for a successful environmental epidemiology study
- direct and accurate estimates of the exposure experienced by the individual members of the study population
- direct and accurate determination of the disease status of individual members of the study population
- appropriate statistical analysis and summarization of the data pertaining to the disease and exposure
toxicology
study of the adverse effects of chemicals on living organisms
- studies the health effects that chemicals can cause and the level of exposure at which they may become hazardous
Mathieu Orfila
- wrote “Trait des poisons: (1813)
- described in detail various types of poisons and their effects
- contributed to the foundations of forensic toxicology
toxicologist
investigates the dose-response relationship and the probability of its occurence
environmental toxicology
impact of pollutants upon the structure and function of ecological systems
ecotoxicology
concerned with toxic effects caused by nature/ synthetic pollutants to the constituents of ecosystems
xenobiotics
chemical substances that are foreign to the biological system including naturally occurring compounds and man made compounds
poison
any agent capable of producing deleterious response in a biological systemt
toxicity
degree to which something is poisonous
toxic agent
material or factor that can be harmful to biological system
toxic substance
material with toxic properties
toxicant
toxic substances that are man made or result from human activity
toxin
toxic substance naturally made by living organisms
systemic toxin
toxins that affect the entire body organ systems
target organ toxin
toxins that affect specific parts of the body
dose
amount of substance administered at one time
- mg/ml (of blood) or mg/kg (body mass)
- fracturing dose administration can change the effects
- lethality relates to body size of the subject
dose response relationship
correlative relationship between the characteristics of exposure to a chemical and the spectrum of effects caused by that chemical
- health affect is the Y axis; expose is the X axis
Can be used to establish:
- the causal association between toxic substances and biological effects
- minimum dosage needed to produce effects
- rate of accumulation of harmful effects
threshold dose response curve
- flat level where increase in dosage produces no effect: subthreshold phase
- after threshold, linear phase where an increase in response is proportional to increase in dose
- curve flatens when max response is reached
- threshold is the lowest dose at which a response may occur
individual dose response curve
graded and increasing response as the dose increase
population dose response curve
relationship of observed responses/outcomes in a population to varying levels of an agent
- sigmoidal shaped curve
Lethal dose
- compares toxicities of different chemicals to describe if a chemical is more or less toxic than another
factors that affect the response to a toxic chemical
- route and site of entry
- length and duration of exposure
- effects of chemical mixtures
- individual responses to toxic exposures
route and site of entry
- ingestion: slightly faster than dermal
- dermal: slowest effect
- inhalation (major exposure route for occupational exposure): slightly slower than injection
- injection into blood stream: fastest effect
length and duration of exposure
- acute: single exposure for less than 24 hours
- subacute: exposure for 1 month or less
- subchronic: exposure for 1 to 3 months
- chronic: exposure for more than three months
- acute exposure may produce acute effects that disappear
- chronic exposure allows for the buildup of effects overtime
additive effects of chemical mixtures
- 1+1=2
- combination of two chemicals produces an effect equal to their individual effects added together
Synergistic effects of chemical mixtures
1+1>2
- combined effect of exposures of two or more chemicals is greater than the sum of individual effects
potentiation effects of chemical mixture
0+1>1
- one chemical that is not toxic causes another chemical to become more toxic
coalitive effects of chemical mixture
0+0>1
- several agents without known toxic effects interact to produce a toxic effect
antagonistic effects of chemical mixtures
1+1<2; 0+1<1
- two chemicals administered together interfere with each other’s actions or one interferes with the action of the others
individual responses to toxic exposures
- direct effect: an immediate impact on the cells and the tissues of the body or upon a specific target organ
- local effects: damage at site where chemical first came in contact with the body
- systemic effects: adverse effects associated with generalized distribution of the chemical throughout the body
- target organ effects: effects confined to specific organs
- indirect effect: a change in the the function of the body’s biomedical processes
latency and delayed response
- latency: time period between initial exposure and measurable response
- carcinogenesis have delayed effect
testing for toxicity
- human study: experiments on human volunteers who have normal or accidental exposures (a type on in vivo experiments)
- animal study: experiments on animals exposed purposivley to target chemical (in vivo experiment)
- cell culture study: experiments on cells derived from human, animal, or plant sources (in vitro experiment)
Risk
- a process for identifying adverse consequences and their associated probability
- known risks vs unknown risks and dread vs. not dread
health risk assessment
- qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards
- four key steps in the risk assessment: hazard identification, dose-response assessment, exposure assessment, and risk chracterization
hazard identification
examine the evidence of an agent of concern on its toxicity to adversly affect human health with the potential to cause a disease or cances
- the only qualitative process in risk assessment
Dose-response assessment
investigate the relationship between the amount of exposure and the occurence of the unwanted health effects
exposure assessment
assess the population exposed to the agent, describes their composition and size, and examine the route, magnitudes, frequencies, and durations of the exposure
- examines the sources and route of the pollutants making contact with the human body, and the concentration levels at the point of contact
- characterize, identify, quantify
- quality of this data determines the accuracy of the of the dose of the contaminant in the human body and the reliability of the risk assessment
risk characterization
estimate the likelihood and number of excuses of unwarranted health events expected from current or potential exposure scenarios
components in a reliable exposure assessment
- exposures of assessment becomes one of the most challenging aspects in risk assessment
risk management
- actions taken to control exposures to toxic chemicals in the environment
- scientific research, risk assessment, risk management
role of environmental policy
- protect the public from environmentally caused adverse health effects
- protection from environmental health hazards is considered a fundamental human right
- goal is to reduce human risks or environmental damages resulting from pollution
principles of environmental policy development
- precautionary principle
- environmental justice
- environmental sustainability
- the polluter-pays principle
precautionary principle
- preventive measures should be taken when a potential hazard or activity raises threats of harm to the environment, wildlife, or human health, even if some cause and effect relationships are not fully established
environmental justice
- denotes the equal treatment of all people in society irrespective of their racial background, country of origin, and socioeconomic status
environmental sustainability
- resources should not be depleted faster than they can be regenerated, and there should be no permanent change to the natural environment
polluter-pays principle
polluters should bear the expenses of carrying out the pollution, prevention, and control measures introduces by public authorities to ensure that the environment is in acceptable state
the policy cylce
- problem definition formulation and reformulation
- agenda setting
- policy establishment
- policy implementation
- policy assessment
relationship of the scientific data to policy development
- creation of sound policy requires foundation of sound data
relationship of risk assessment to policy development
risk assessment is closely aligned with the policy process through balancing of economic and other costs with health and societal benefits
environmental impact assessment (EIA)
any changes to the environment, whether adverse or beneficial, wholly or partially, resulting from an organizations activities, products or services
Health impact assessment (HIA)
method for describing and estimating the effects that proposed project or policy may have on the health of a population
environmental health regulation agency at an international level
World Health Organization (WHO)
environmental health regulation agency at a national level
EPA, protects human health and safeguarding the nature of the environment
- established in 1970
- give grants, study environment, sponser partnerships, teach, publish info
environmental health regulation agency at a state level
individual states and local governments
Agency for toxic substance and disease registry (ATSDR)
- nations public health agency for chemical safety
- created by the CERCLA of 1980 (superfund law)
National institute of environmental health sciences
(NIEHS)
- discover how the environment impacts people in order to promote healthier lives
- focuses on the environmental cause of disease
National Institute for occupational safety and health (NIOSH)
- prevention of work related injury and illness
- created the OSHA of 1970
National environmental policy act (NEPA)
- 1969
- one of the first laws to establish the broad national framework for environmental protections
- requires all branches of the government give proper consideration to the environment before taking any major federal action
Clean Air Act (CCA)
- 1970
- regulates air emissions
- authorizes EPA to establish NAAQS to protect public health
Occupational Safety and Health Act of 1970
- Make sure employers provide their workers a hazard free place of employment
- created national institute for occupational safety and health (NIOSH)
clean water act
- 1972
- was an ammendment to the federal water pollution control act
- established basic structures for regulating pollutants discharged into us waters
- gives EPA the authority to implement pollution control programs
safe drinking water act (SDWA)
- 1974
- protects quality of all drinking water
- authorizes the EPA to establish minimum standards to protect tap water and requires all owners and operators to complu
Toxic Substances Control Act (TSCA)
- 1976
- gives EPA the authority to require reporting, record keeping, and testing requirements, and restrictions relating to chemical substancs
CERCLA (superfund) of 1980
- provides federal superfun to clean up uncontrolled or abandoned hazardous waste sites
- gives EPA the authority to to seek out parties responsible and ensure their cooperation in the cleanup
Federal insecticide, fungicide, and rodenticide act (FIFRA) or 1996
- provides federal regulation of pesticide distribution, sale, and use
- all pesticides distributed or sold in the US must be registered by the EPA
