Environmental Health Exam 1 Notes

Poison

"...any agent capable of producing a deleterious response in a biological system."

Environmental Policy

"A statement by an organization [either public, such as government, or private] of its intentions and principles in relation to its overall environmental performance." Environmental policy provides a framework for action and for the setting of its environmental objectives and target."

Environmental Health (Definition)

"Promote health for all through a healthy environment." - Healthy People 2010

Bias

"Systematic deviation of results or inferences from the truth. Processes leading to such deviation. An error in the conception and design of a study—or in the collection, analysis, interpretation, reporting, publication, or review of data—leading to results or conclusions that are systematically (as opposed to randomly) different from the truth."

Ecological Model

(outwards over life span) 1. innate traits, biological traits and disease 2. individual behavior 3. social, family, community networks 4. living and working conditions 5. broad social, economic, cultural, health, and environmental conditions and policies (global, national, state, local levels)

Factors that affect the concentration and toxicity of a chemical

-Route of entry into the body -received dose of the chemical -Duration of exposure -Interactions that transpire among multiple chemicals -Individual sensitivity

Three Major Historical Events in Environmental Epidemiology

-Sir Percival Pott and scrotal cancer among chimney sweeps in England -John Snow and cholera -

Malthusian Predictions

-Thomas Malthus predicted human pop would grow exponentially. positive checks: epidemics, starvation, warfare preventative checks: not allowing people to marry.

Negative Impacts of Pollution

-combustion of fossil fuels -global warming -disease carrying insects

Epidemiologic Contributions to Environmental Health

-concern with populations -use of observational data -methodology for study designs -descriptive and analytic studies. important to study of environmental health problems because -many environment-related issues occur at population level -methods of experiments and observational techniques -study designs can be used for environmental issues -epidemiology aids in the development of hypotheses and study of causal relationships.

Ch 2 Learning Objectives

-define environmental epidemiology -describe three major historical events in environmental epidemiology -provide examples of epidemiologic tools used in environmental health -identify types of associations found between environmental hazards and health outcomes -list study designs used in environmental epidemiology.

Ch 1 Learning Objectives

-describe how environmental health problems impact our lives -describe the potential impacts of population growth upon the environment -state a definition of the term environmental health -list at least 5 major events in the history of environmental health -identify current issues in the environmental health field -describe employment opportunities in the environmental health field

Negative Impacts of Poverty

-determinant of adverse health outcomes.

Determinants of Health

-physical environment -social environment -personal lifestyle -constitutional factors (hereditary/human biology) -health care systems/access to medical care

Principal Determinants of Health

-three 'P's - pollution, population, and poverty -Prof Warren Winkelstein -three Ps are associated with each other

Threats to the Environment

-trash -hazardous wastes in disposal sites -air pollution -toxic chemical exposure -deforestation

Loss of Biodiversity

-variability of animal and plant species and ecosystems. -human activities lead to spread of insect vectors, extinction of species, loss of flora (pharmaceuticals)

Negative Impacts of Population Growth

10-12 billion during 21st century, estimated 8 billion by 2018-2028. -overtaxing carrying capacity -food insecurity -loss of biodiversity -food industry: crowded animals in factories lead to pandemics (bird flu from poultry farms in Asia) -conversion of large rural and forested areas into cities (urbanization) -urbanization increases rate of morbidity and mortality. -increased burden of disease, whether chronic, communicable, or degenerative. -increased poverty as living spaces decline and pop density increases.

Carcinogen

A chemical (or substance) that causes or is suspected of causing cancer, a disease associated with unregulated proliferation of cells in the body.

Ecosystem

A dynamic complex of plant, animal and microorganism communities and the nonliving environment interacting as a functional unit.

Dose-Response Relationship

A type of correlative relationship between "the characteristics of exposure to a chemical and the spectrum of effects caused by the chemical."

Dose-Response Curve

A type of graph used to describe the effect of exposure to a chemical or toxic substance upon an organism such as an experimental animal.

Terms Describing Duration of Exposure

Acute - usually a single exposure for less than 24 hours Subacute - exposure for one month or less Subchronic - exposure for one to three months Chronic - exposure for more than three months

Effects of Chemical Mixtures

Additive means that the combination of two chemicals produces an effect that is equal to their individual effects added together. Synergism indicates that the combined effect of exposures to two or more chemicals is greater than the sum of their individual effects. Potentiation happens when one chemical that is not toxic causes another chemical to become more toxic. Antagonism means that "two chemicals administered together interfere with each other's actions or one interferes with the action of the other."

Agent Aspect of Epidemiological Triangle

Agent refers to "A factor, such as a microorganism, chemical substance, or form of radiation, whose presence, excessive presence, or (in deficiency diseases) relative absence is essential for the occurrence of a disease."

John Snow

An English anesthesiologist who linked a cholera outbreak in London to contaminated water from the Thames River in the mid-1800s. • Snow employed a "natural experiment," a methodology used currently in studies of environmental health problems.

Ch. 4 Learning Objectives

By the end of this chapter the reader will be able to: -Describe key environmental health regulatory agencies at the international, national, state/provincial, and local levels -State four principles that guide environmental policy development -Discuss five major environmental laws that have been introduced within the past 10 years -Describe environmental policies designed to protect vulnerable groups List the steps in the policy-making process

Case Series Study

Case Series - gather information over time about people with a certain condition (e.g. cases) • this is a weak type of study design but can be useful for generating hypotheses.

Causality

Certain criteria need to be taken into account in the assessment of a causal association between an agent factor (A) and a disease (B).

Cohort Study

Compares persons who have or have not been exposed. • Subjects are followed longitudinally to observe development of a disease outcome (e.g. incidence)

Cross Sectional Study

Cross-sectional - both outcome and exposure are measured in a cross-section of the population • this study design can asses disease prevalence at a point in time

Hazard Identification

Definition: hazard "Inherent capability of an agent or a situation to have an adverse effect." Hazard identification: "examines the evidence that associates exposure to an agent with its toxicity and produces a qualitative judgment about the strength of that evidence..."

Risk Characterization

Develops "estimates of the number of excess unwarranted health events expected at different time intervals at each level of exposure." (quantitative) Another approach is to put the risk to health into categories . (Example- This waste site is a public health hazard at the present time.) (qualitative)

Concerns with Population

Environmental epidemiology studies a population in relation to morbidity and mortality. Example: Is lung cancer mortality higher in areas with higher concentrations of "smokestack" industries?

Environmental Toxicology

Environmental toxicology examines how environmental exposures to chemical pollutants may present risks to biological organisms, particularly humans, but also animals, birds, and fish.

Use of Observational Data

Epidemiology is primarily an observational science that takes advantage of naturally occurring situations in order to study the occurrence of disease

What is an exposure assessment?

Estimating concentrations in the environment using models Assessing exposures among populations Assessing exposures using monitoring data Assessing exposures using models

Types of Doses

Exposure dose Absorbed dose Administered dose Total dose External dose Internal dose Inhaled dose Biologically effective dose

Most common parts of body involved in exposure to environmental chemicals

GI tract Respiratory system Skin/Dermal Inhalation Ingestion Injections into bloodstream

Environmental Heath Field

Hippocrates "father of medicine" environmental effects on health four body humors (yellow bile, black bile, phlegm, blood) equilibrium Five major events: -Jenner method for smallpox vaccination in 1796. -Upton Sinclair's The Jungle about Chicago meat processing industry led to first Food and Drug Act in 1906. -US National Park System created in 1916. -John Snow's hypothesis of outbreak in London in 1849. -EPA founded in 1970.

Careers in Environmental Health Field

Hygienist Toxicologist Environmental Health Inspector Vector Control Specialist Research Analyst Environmental Lawyer Occupational Health (Physician/Nurse)

Mathieu Orfila

In the 1800s, he authored a number of significant works, among them Traité des Poisons (1813). This work described various types of poisons, their bodily effects, and methods for detecting the presence of poisons in the body. These developments contributed to the foundations of forensic toxicology.

Direct Adverse Effects of Exposure to Chemicals

Local effects - damage at the site where a chemical first comes into contact with the body. Systemic effects - generalized distribution of the chemical throughout the body by the bloodstream to internal organs. Target organ effects - some chemicals may confine their effects to specific organs.

Dose-Response Assessment

Measures "the relationship between the amount of exposure and the occurrence of the unwanted health effects."

Types of Dose-Response Curves

One for the responses of an individual to a chemical. One for a population

Risk Management

Oriented toward specific actions and "consists of actions taken to control exposures to toxic chemicals in the environment. Exposure standards, requirements for premarket testing, recalls of toxic products, and outright banning of very hazardous materials are among the actions that are used by governmental agencies to manage risk.",

Paracelsus

Paracelsus was one of the founders of modern toxicology. He was a Swiss-German who was active during the time of da Vinci and Copernicus (early 16th century). His contributions included the concept of the dose-response relationship and the notion of target organ specificity of chemicals.

Experimental Study

Perform an intervention and observe the results. • this type of study present serious ethical dilemmas if the intervention is not known in advance to not result in harm.

Measures of Disease Frequency

Prevalence Point prevalence Incidence Incidence rate Case fatality rate

Case Fatality Rate (CFR)

Provides a measure of the lethality of a disease. -# of deaths due to X/ # of cases of disease X

Risk Assessment

Provides a qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. 1. Hazard identification 2. Dose-response assessment 3. Exposure assessment 4. Risk characterization

Dose

Refers to "the amount of a substance administered at one time."

Toxicity

Refers to "the degree to which something is poisonous." Related to a material's physical and chemical properties

Point Prevalence

Refers to all cases of a disease, health condition, or deaths that exist at a particular point in time relative to a specific population from which the cases are derived. # persons ill/total # in group

Prevalence

Refers to the number of existing cases of a disease, health condition, or deaths in a population at some designated time

Fields within Toxicology

Regulatory Forensic Clinical Environmental Reproductive Developmental

Examples of Toxic Plants

Some mushrooms (e.g., Amanita phalloides, "death cap") Poison hemlock Foxglove Poison oak/poison ivy Rhubarb, especially the leaves, which have high levels of oxalates (stems make delicious pie) Some houseplants such as dieffenbachia.

Principles of Environmental Policy Development

The precautionary principle Environmental justice Environmental sustainability The polluter-pays principle

Exposure Assessment

The procedure that "identifies populations exposed to the toxicant, describes their composition and size, and examines the roots, magnitudes, frequencies, and durations of such exposures. Who or what is exposed (e.g., people, aquatic ecosystems)? - Does the exposure occur through breathing air, drinking water, skin contact or any other routes? - How much exposure occurs? - How often and for how long does exposure occur, that is, what is its frequency and duration?

Environmental Epidemiology

The study of diseases and health conditions that are linked to environmental factors.

Testing for Toxicity

The subjects used for testing the toxicity of chemicals include the following: -Volunteers who have had normal or accidental exposures -Animals exposed purposively (in vivo experiments) -Cells derived from human, animal, or plant sources (in vitro experiments)

Environment Aspect of Epidemiological Triangle

The term environment is defined as the domain in which disease-causing agents may exist, survive, or originate; it consists of "All that which is external to the individual human host."

Latency

The time period between initial exposure and a measurable response. The latency period can range from a few seconds (in the case of acutely toxic agents) to several decades for agents that may be carcinogenic.

Lethal Dose

To describe toxic effects, toxicologists use the symbol LD50, which is "the dosage (mg/kg body weight) causing death in 50 percent of exposed animals." Used to compare the toxicities of different chemicals. Examples: sucrose - 30 g/kg vitamin C - 12 g/kg ethanol - 7 g/kg acetaminophen - 2 g/kg formaldehyde - 700 mg/kg mercury chloride - 40 mg/kg

Toxicants

Toxic substances that are man-made or result from human (anthropogenic) activity.

Toxicology

Toxicology is defined as "the study of the adverse effects of chemicals on living organisms."

What is the epidemiologic triangle?

Used for describing the causality of infectious diseases. • Provides a framework for organizing the causality of other types of environmental problems Host Environment Agent

Toxin

Usually refers to a toxic substance made by living organisms including reptiles, insects, plants and microorganisms.

Physical Environment

air, water, soil

Demographic Transition

alterations over time in a population's fertility, mortality and make-up. -three stages of "transition" pyramid 1. First stage. -most of pop is young and fertility/mortality rates are high. Overall, small pop. 2. Second stage. -drop in mortality rates. fertility rates remain high. rapid increase in pop among younger groups. 3. Third stage. -dropping fertility rates that cause a more even distribution of the pop according to age/sex.

Migration

cause of population growth -search for economic betterment -escape from persecution -relief from unstable conditions

Environmental Risk Transition

changes in environmental risks that happen as a consequence of economic development in underdeveloped regions of the world. -typically household disks, such as poor food, air, and water quality. -diarrhea from poor hygiene or water, respiratory diseases because of indoor air pollution and poor housing, and malaria.

Case-Control Study

compares persons who have a certain disease outcome (cases) with persons who do not (controls). • Exposures that might have possibly influenced the disease outcome are determined retrospectively.

Ecologic Study

compares the rates of a disease outcome in one population to another • e.g. do persons whose household income is less than $40,000 per year have a higher rate of lung cancer than persons whose income is higher?

Environment

complex of physical, chemical, and biotic factors that act upon an organism or an ecological community and determine its form and survival.

Mortality

declined over time through public health measures, famine control, and availability of drugs and vaccines.

Social Environment

housing, transport, urban development, land use, industry, agriculture, exposures like work-related stress and violence.

Population Dynamics

interrelationships among set of variables that influence the demographic makeup of populations, and variables that influence growth/decline of population sizes. -size, age, sex, fertility, death rates, migration.

Natural Experiments

naturally occurring circumstances in which subsets of the population have different levels of exposure to a causal factor. this tends to resemble actual experiments with random groups.

Carrying Capacity

population that an area will support without undergoing environmental deterioration. Animal population: -limited by lack of resources, food, disease Human population: -limited by lack of resources, agricultural land, diverse plant and animal species.

Epidemiologic Transition

shift in pattern of morbidity and mortality from causes related to infectious disease, communicable disease, chronic disease. -accompanies the demographic transition. -has already occurred in most developed countries over a century.

Food Insecurity and Famine

supplies of wholesome foods are uncertain or limited. -occurs when carrying capacity is exceeded. -mortality may be brought into balance with fertility if population mortality increases during famine.

Fertility

total fertility rate (TFR) - estimate of completed fertility. indicates how many births a woman would have by the end of her reproductive life. Natural population replacement rate is 2.1 TFR is around 2.0 to 2.1 births per woman in the US. -over 3.5 during baby boom era.

Megacities

urbanized areas with 10 million or more inhabitants. -25 megacities in beginning of 21st century ex. tokyo, mumbai, sao paulo, shanghai, mexico city, NY, LA.

Sir Percivall Pott (1714-1788)

• A London surgeon thought to be the first individual to describe an environmental cause of cancer. • Chimney sweeps had high incidence of scrotal cancer due to contact with soot.

Host Aspect of Epidemiological Triangle

• A host is "a person or other living animal, including birds and arthropods, that affords subsistence or lodgment to an infectious agent under natural conditions."

Confounding

• Denotes "... the 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." • Or "anything that is associated with both the exposure and the outcome, but not on the same causal pathway."

Study Designs Used In Environmental Epidemiology

• Experimental • Case Series • Cross-Sectional • Ecologic • Case-Control • Cohort

Limitations of Epidemiologic Studies

• Long latency periods • Low incidence and prevalence • Difficulties in exposure assessment • Nonspecific effects

Healthy Worker Effect

• Refers to the observation that employed populations tend to have a lower mortality experience than the general population. • The healthy worker effect could introduce selection bias into occupational mortality studies.

Hill's Criteria of Causality

• Strength • Consistency • Specificity • Temporality • Biological gradient • Plausibility • Coherence

Relative Risk (RR)

• The ratio of the incidence rate of a disease or health outcome in an exposed group to the incidence rate of the disease or condition in a non-exposed group.

Study Endpoints

• The ratio of the incidence rate of a disease or health outcome in an exposed group to the incidence rate of the disease or condition in a non-exposed group.

Issues in Environmental Health Field

- 40% world's deaths caused by environmental factors. -most chronic diseases are result of interactions between environmental and genetic factors. -vulnerable subgroups: elderly, disabled and chronically ill, pregnant women, children -developing countries have worse problems than developed countries due to better access to medical care and pollution controls in developed countries, even though developed world has more industrial pollution.

Urbanization

-5% in 1800 to 50% in 2000 factors that lead to urbanization: -industrialization -food availability -employment opportunities -lifestyle considerations -escape from political conflict

Classes of Epidemiologic Studies

-Descriptive -Analytic Descriptive epidemiology- occurrence of disease in populations according to classification by person, place, and time variables. Analytic epidemiology- causal hypothesis regarding association between exposures and health conditions. analytic methods through exposure and outcome variables.

Odds Ratio (OR)

A measure of association for case- control studies. • Exposure-odds ratio: • Refers to "... the ratio of odds in favor of exposure among the cases [A/C] to the odds in favor of exposure among the non-cases [the controls, B/D]." • The ratio of the odds of exposure between the disease and non-disease groups

What is a toxicologist?

A scientist who has received extensive training in order to investigate in living organisms "the adverse effects of chemicals . . . (including their cellular, biochemical, and molecular mechanisms of action) and assess the probability of their occurrence."

Ch. 3 Learning Objectives

By the end of this chapter the reader will be able to: -Define the term toxicology -Define three important terms used in the field of toxicology -State five factors that affect responses to a toxic chemical -Discuss the steps involved in risk assessment -Describe methods for human exposure assessment

Incidence

The occurrence of new disease or mortality within a defined period of observation (e.g., week, month, year, or other time period) in a specific population. incidence rate = # of new cases over time period/total pop at risk * multiplier (ex. per 10000)