4HH3 Terms PDF

4HH3 Terms Introduction Environment Personal Environment Includes the person’s individual characteristics and behaviours that affect their health EXAMPLES: Diet, exercise, lifestyle choices, genetics External Environment Includes the physical environment/conditions that a population resides and ope...

4HH3 Terms Introduction Environment Personal Environment Includes the person’s individual characteristics and behaviours that affect their health EXAMPLES: Diet, exercise, lifestyle choices, genetics External Environment Includes the physical environment/conditions that a population resides and operates within EXAMPLES: Clean/unclean water, air pollution, working conditions, housing Socio-Economic Environment Includes the institutional systems of a population that impact their resources, money, and their health EXAMPLES: Welfare state, universal health care these environments overlap. Together, they create different conditions that can affect a population’s & individual’s health. Epigenetics - Study of how your behaviours and environment can cause changes to how your genes work - Epigenetic changes are reversible and do not change your DNA sequence, but they change how your body expresses DNA sequences Sustainable Development Goals - The Sustainable Development Goals (SDGs), also known as the Global Goals, were founded by the United Nations. It is comprised of 17 interlocked goals that are a “universal call to action to end poverty, protect the planet, and ensure that by 2030 all people enjoy peace and prosperity.” - All member UN member states have adopted the goals. In addition to the goals, each goal has set targets that serve as indicators of progress. Disease - Any harmful deviation from the normal structural or functional state of an organism i.e., a reduction in one or more functional abilities below typical efficiency Illness - A feeling, an experience of unhealthy, which is entireness personal, interior to the person of the patient Health - A state of complete physical, mental, and social well-being, and not merely the absence of disease of infirmity Measures of Health - There are several possible ways to measure health, but it can be understood through the body’s structure & function, absence or presence of disease, or it’s symptoms and what it can and cannot do - Morbidity, mortality, Self-rated health, Self-rated Life Satisfaction, Perceived Happiness, Perceived Sense of Belonging, Life Expectancy, Disability Adjusted Life Years, Perceived Quality of Life Disability Adjusted Life Years (DALY’s) - One DALY represents the loss of the equivalent of one year of full health. DALYs for a disease or health condition are the sum of the years of life lost to due to premature mortality (YLLs) and the years lived with a disability (YLDs) due to prevalent cases of the disease or health condition in a population. - DALYs for a specific cause are calculated as the sum of the years of life lost due to premature mortality (YLLs) from that cause and the years of years of healthy life lost due to disability (YLDs) for people living in states of less than good health resulting from the specific cause. - Leading cause of DALY’s in Canada are heart disease, lung cancers, dementias Life Expectancy - Number of years a person expects to live, based on an estimate of the average age that members of a particular group will be when they die Mortality Rate - Measure of the frequency of occurrence of death in a defined population during a specific interval (typically per 1000 or 100,000) Incidence rate - Frequency of new occurrences of a medical disorder in a population in a given period of time - Tells us about the risk of an event within a period of time Rising incidence - Means an increased rate of new cases and an increased risk - Example: HIV incidence is not increasing, due to many interventions and treatments. - MPOX is increasing in several African countries Proportion prevalence - The percentage/proportion of a population that is affected by a particular medical disorder at a given time or period of time - Tells us about the disease burden in a population at a moment in time Rising Prevalence - Can mean many things, prevalence relies on rate of new cases, average duration of disease, and can decrease if the disease is cured, or the patient dies. - Example: HIV prevalence has been increasing, due to many existing cases. - MPOX is rising in prevalence in Africa Hazards Hazard, Exposure Outcome Model - The hazard exposure outcome model is a framework often used to help perform risk assessments (i.e., the possibility of harm) Hazard - Something that has the potential to do harm to health and well-being - Hazard evaluations focus on defining what types of harmful effects could occur under what circumstances (i.e., ingestion, inhalation, etc.) Risk - The likelihood or probability that harm from a specific hazard will occur - Risk = Hazard x Exposure Hazard VS Risk - Asbestos fibres (hazard) embedded in old building materials are only a risk if they are released into the air that you breathe in. Types of Hazards Physical - Chemical: A natural or synthetic substance that causes direct harm to human tissue - Legal Dose Thresholds: Often reported in lethal dose thresholds - LD50: Amount of material, given all at once, which causes death to 50% of a group of test animals, is one way to measure the short-term poisoning potential (acute toxicity) of a material - Radiation - Ionizing: Radiation that can transfer energy resulting in charged cellular particles. Short wavelength, high frequency, higher energy; can denature proteins and damage DNA Ex. X-Rays, radioactive decay - Non-Ionizing: Does not have enough energy to remove an electron from an atom or molecule. Longer wavelength, lower frequency, lower energy; can cause thermal damage to humans - UV radiation: a form of non-ionizing radiation emitted by the sun and other artificial sources (ex. Tanning beds and UV lamps) Mechanical - Energy transmitted in a quantity that exceed ability of tissue to resist harm - Occupational: Slippery floors, falls, poorly maintained equipment and infrastructure, loud noises, unguarded walkways moving equipment, etc  - Community: Sports-related injuries, motor vehicle accidents, fall injuries (particularly among the elderly), any non-occupational related physical injury Biological - Virus, bacteria, prion, fungus, or parasitic organism that can cause harm if inhaled, eaten, or come into contact with the skin - Infection intensity: Number of microorganisms in an infected host - Other evidence of infection: Detection of genetic material, antibodies, antigens Social Hazards - Institutional hazards that limits a person’s access to health services, water, food, transportation or increases their risk of health complications Exposure Exposure - combination of concentration and the route of exposure Exposure concentration - Quantity + time Background Radiation - Background radiation is a constant source of ionizing radiation, one of the sources includes cosmic radiation - Cosmic Radiation: High energy charged particles, X-rays, and gamma rays produced in space (sources include: the Sun and other celestial bodies) - Regions at higher altitudes receive more cosmic radiation Chernobyl Health Impact Workers: - There were 600 workers onsite, 134 suffered ARS and 28 died within the first 3 months of exposure. - Of the other onsite 600 workers, increased incidences of leukemia and cataracts were recorded for those exposed to higher doses of radiation. - The 530,000 registered recovery operation workers who worked onsite between 1986 and 1990 were exposed to doses ranging from 20 to 500 mSv (averaging 120 mSv) Public: - Doses: - When iodine-131 is released into the environment, it is quickly taken up by the thyroid gland. Children are especially vulnerable, because their thyroid gland is smaller and they have a higher metabolism. - The 115,000 members of the public who had to be evacuated from the area around the plant received an average effective radiation dose of 30 mSv (recall: normal levels are 3-4 mSv) - Cancers:  - There had been almost 20,000 cases of thyroid cancer reported in children and adolescents who were exposed to iodine-131 at the time of the accident. - Approximately 5,000 of these thyroid cancers are likely attributable to children drinking fresh milk containing radioactive iodine from cows who had eaten contaminated grass in the first few weeks following the accident. Exposure Concentration - Time Acute: - Exposure to hazard is acute if the effects (if any) are quickly resolved, and does not build up over time - Usually refers to single incident of exposure that is short in duration with effects that are immediate and severe - Ex: carbon monoxide poisoning Cumulative - Exposure to hazard is cumulative if our bodies can’t fully eliminate the hazard over time - Gradual exposure to pollutants & other sources of illness are also examples of cumulative exposure - Ex: parasites, lead in blood, nickel Route of Exposure - Exposure route is the pathway that a contaminant enters an individual or population after contact. Typically, exposure occurs by one of three exposure routes—inhalation, ingestion, or dermal. - Inhalation is the most rapid route of uptake, followed by dermal contact and ingestion. The health effects may vary significantly among the exposure routes Route of Exposure Interfaces - Different routes of exposure can result in different system effects - inhalation -> respiratory - Ingestion -> gastrointestinal - Skin Contact/Dermal -> skin and tissue Exposure vs Susceptibility - Both social and physical environments contribute to a population’s vulnerability to disease. - The concepts of exposure and susceptibility can help characterize how the social & physical environments affect a population’s health Exposure: - Concerned with the conditions that are conducive to the presence of a disease - Ex: Climate, crowding, land-use, temperature Susceptibility - How sensitive a person/population is to contracting a disease upon exposure - Ex: Stress, access to healthcare, education, underlying health conditions Toxicology Toxin: Natural products such as ones found in poisonous mushrooms Toxicant: Man-made products, artificial products introduced into environments Ecological receptor: - the ecological entity exposed to the stressor/hazard - Ex: People living near industrial sites, those living in houses with radon, pedestrians exposed to air pollution Routes of Exposure: inhalation, absorption, ingestion Antibodies: are proteins produced by the body to neutralize or destroy toxins or disease-carrying organisms. Antibodies are disease-specific Immunity: A person gains immunity by having antibodies against that disease Dose: - The amount of a substance/hazard that enters or contacts a person, also termed as the amount of exposure to a hazard - Exposure is contact. No matter how dangerous a substance or activity, without exposure, it cannot harm you Measuring Doses: - When a contaminant is taken into the body, the amount that gets into the body in a biologically available form is called the dose - Potential amount of contaminant inhaled/ingested - Applied amount of the contaminant at the absorption barrier (skin, lungs, GI tract) - Internal amounts of contaminant that gets past the barrier into the body (bloodstream) - Effective contaminant that interacts with the internal target tissue or organ Dose-Response: - The relationship between the dose of exposure and the response on individuals or populations - A dose-response relationship is one in which increasing levels of exposure are associated with either an increasing or a decreasing risk of the outcome (i.e, drugs, toxic substances Continuous graded dose response curve: Represents the relationship between relationship between dose of exposure to hazard and severity of response (i.e., as the concentration of a drug increases, its biologic effect gradually increases) Quantal dose response curve: - The relationship between dose of exposure to hazard and the probability of an event (i.e., disease or death), particularly if the response is an “either-or” event, such as prevention death usually measured as a % of population (i.e., animal and clinical trials - dose-response curves are nonlinear; they have thresholds and exhibit multiphasic responses Hormesis: the practice of adding some stress or some toxicity in small amounts that is actually beneficial to you (i.e., radiation in cancer therapy) Threshold Effect: - Something that occurs only once a critical threshold has been reached. It is often used to determine the highest possible safest dose - An ecological threshold is the point at which there is an abrupt change in the structure, quality, or functioning of an ecosystem or where external changes produce large and non-reversible responses in an ecosystem NOAEL: - No observed adverse effect level - Highest experimental point that is without adverse effect - Under laboratory conditions, it is the level where there are no side-effects - In toxicology it is specifically the highest tested dose or concentration of a substance (i.e., a drug or chemical) or agent (e.g., radiation), at which no such adverse effect is found in exposed test organisms where higher doses or concentrations resulted in an adverse effect LOAEL: - lowest observed adverse effect level - Lowest concentration or amount of a substance found bycexperiment or observation that causes an adverse alteration of morphology, function, capacity, growth, development, or lifespan of a target organism Non Threshold effect risk: effects that occur at any level (i.e., no NOAEL) Ex: Genotoxic Carcinogens, cancer causing agents (i.e., formaldehyde, acetaldehyde, benzo[a]pyrene and aflatoxin B1) Non Threshold effect risk contexts: Occupational vs community exposure - Is the worker informed about hazards? - Has employer done due diligence? - Is the worker being compensated (‘hazard pay’) Adults vs Children - Exposure in children has more unknowns - Children don’t participate in the decision-making - Children often have greater cultural value Economic and social benefits - Many forms of pollution may have non-threshold effects, but are a by- product of economic activity that creates wealth, and greater wealth can sometimes save lives Pathology & Pathogenesis Pathology: A branch of medical science that studies the diagnosis of disease Pathogenesis: The process/mechanisms in which infection (exposure to hazard) leads to states of disease Pathogen: - Includes bacteria, fungi, protozoa, worms, viruses, parasites, and infectious proteins that cause infectious diseases - Ex: Giardia parasites (germ) causes Giardiasis, a diarrheal disease. The parasite lives in the intestines and is passed in stool (poop) Chain of transmission: how an infection spreads based on a sequence of 6 stages Infectious agent → reservoir → portal of exit → mode of transmission → portal of entry → susceptible host Reservoir: the habitat in which an infectious agent (pathogen) lives, grows, and multiplies, can act as a source of reinfection for human populations Human reservoir: - Humans infected with a pathogen that lives on or within the human body, once a person carries an infectious agent, they are called a carrier - A disease is considered to have human reservoirs when they are transmitted from human to human without intermediaries, they include sexually transmitted diseases, respiratory illnesses, measles, etc. Animal reservoir: - Animals that host pathogens on or within their bodies - When a disease spreads from an animal to a human it is called a zoonotic disease - Examples include diseases like rabies (bats, racoons, dogs, other mammals), avian and swine flu (birds and pigs), plague (rodents), etc Environment reservoir: - Include entities in the environment that host pathogens, like soil or water - Examples include tetanus caused by a bacterium called Clostridium tetani in soil, dust, and manure. - The spores develop into bacteria when they enter the body. Unlike other vaccine- preventable diseases, tetanus is not spread from person to person. Also, Legionnaire’s disease in water Portal of exit: - How an infectious agent gets out of its reservoir/host - Examples include: mouth (vomit, saliva via sneezing/coughing), cuts in the skin (blood), toileting (stool) Mode of Transmission: Direct contact - Human contact: Transfers from one person to another, can occur through skin-to-skin contact, kissing (i.e., mononucleosis “kissing disease”), sexual intercourse (i.e., gonorrhea - Environmental: Transfers through contact with soil or vegetation harbouring diseases (i.e. hookworm is spread through contact with contaminated soil OR schistosomiasis through contact with contaminated water) - Droplet spread: Refers to spray with relatively large (>5 microns), short-range aerosols produced by sneezing, coughing, or even talking. It is considered direct  because transmission occurs via direct spray, in close range, before the droplets fall to the ground or other surfaces (i.e., influenza) Indirect Transmission: Transfer of infectious agents from a reservoir to a host via air particles, vehicles, or vectors - Airborne: Aerosols (droplet nuclei) are smaller than droplets (