Untitled Flashcards Set
—--------------------------------------------------- LECTURE 7 ----------------------------------------------------
1. Infectious Disease: Host-Centered Concept
The human body is a habitat for many organisms.
Pathogens = Disease-causing agents (germs).
Zoonosis = Infectious disease transmitted from animals to humans.
2. Types of Pathogens
Worms – Multicellular parasites.
Protozoa – Unicellular parasites.
Bacteria – Unicellular; most are not parasitic (Living off another living thing (host) and causing harm.)
Can be aerobic (need oxygen) or anaerobic (don't need oxygen).
Some form spores for survival.
Viruses – DNA or RNA strands; parasitic.
3. Body’s Defense Against Pathogens
Immune system recognizes “self” (own cells) vs. “foreign” (harmful) invaders.
Active immunity – Body produces antibodies after infection or vaccination. (antigen)
Passive immunity – Antibodies are given (e.g., from mother to baby). (antibody)
Herd immunity – If enough people are immune, disease spread slows down.
4. Strategies for Managing Disease Transmission
Segregation – Keeping sick/exposed individuals away from others.
Isolation – For infected individuals.
Quarantine – For exposed but not yet sick individuals.
Sanitation – Clean water, hygiene, and waste control reduce infections.
Vaccination – Prevents diseases by building immunity.
Antibiotics – Treat bacterial infections but overuse causes resistance. (not work)
Methicillin-resistant Staphylococcus aureus MRSA – An antibiotic-resistant bacterial infection.
Pesticides – Control disease-carrying insects (vectors).
Vectors = Spread diseases but don’t get sick.
5. How Infectious Diseases Spread
Close contact → Touching, sneezing, kissing
Droplet Transmission (cough/sneeze) → Flu, COVID-19, measles
Oral contact (kissing, sharing drinks) → Strep, herpes, mono
Fomites (contaminated objects) → Clothing, bedding, hair
Airborne (tiny floating particles) → Can stay in air longer than droplets
Fecal-oral (infected poop to mouth) → Dirty hands, food, water, soil
Examples: Cholera, typhoid, hepatitis A, polio
Foodborne (contaminated food) → Flies can spread germs
Waterborne & soil → Diseases from water or dirt
Examples: Guinea worm, tetanus
6. Global Infectious Disease Patterns
Infectious diseases cause 12.3 million deaths annually.
Top causes of death:
Respiratory infections – 29%
Diarrheal diseases – 20%
HIV/AIDS – 14%
Most affected regions 22% of all death:
Africa (53%), Southeast Asia (27%), Eastern Mediterranean (25%).
7. Infectious Diseases & Cancer
Some infections increase cancer risk due to chronic irritation & cell changes.
Known infectious causes of cancer account for ~18% of cancers worldwide:
Liver cancer – Hepatitis B & C, liver fluke.
Cervix cancer – HPV (Human Papillomavirus).
Stomach cancer – H. pylori (bacteria).
8. Important Diseases & Pathogens
Bacterial Diseases
Tuberculosis (TB) – (world’s deadliest disease)
Global stats:
1/3 infected worldwide
9 million new cases/year, 1.4 million deaths/year
TB kills many people with HIV
Symptoms:
Chest pain, blood in cough
Long cough, fever, chills
Night sweats, weight loss
How it spreads: Cough, sneeze, speak, kiss, spit of sick person
Anthrax
Cause: Bacillus anthracis (spore-forming bacteria, bioterrorism risk).
Transmitted: Through skin contact, inhalation, or eating contaminated food.
Forms of Anthrax:
Cutaneous: (95% of cases) comes from infected animal products, starts as a bump, turns into a painless ulcer within 1-12 days, and can be deadly if untreated.
Inhalation: deadliest form, starts with flu-like symptoms, can lead to respiratory failure and meningitis within 1-60 days, and has a 75% death rate even with treatment.
Gastrointestinal: comes from eating contaminated meat, causes nausea, vomiting, and bloody diarrhea within 1-7 days, and has a 25-60% death rate, with unclear treatment effectiveness.
Bioterrorism: anthrax powder often in suspicious mail; if received, avoid opening, report it, and get tested—antibiotics and vaccines can help.
Plague – Can be used as a bioweapon; treated with antibiotics.
Viral Diseases
Yellow Fever: is a virus spread by mosquitoes with an incubation period of 3-6 days.
The first phase causes fever, muscle pain, backache, headache, and vomiting, with 85% of people recovering.
In severe cases, the toxic phase develops, leading to jaundice, internal bleeding, and kidney failure, with only 50% surviving if untreated. They die after 10-14 days
The disease originated in West Africa, spread to the Americas, and caused deadly outbreaks.
By the mid-1900s, North America eradicated yellow fever through vaccination and mosquito control.
It still exists in 9 South American countries, some Caribbean islands, and 33 African countries.
HIV: spread through blood, semen, vaginal fluid, or breast milk, weakens the immune system, and causes life-threatening infections
It was first recognized in 1981, affects 37.9 million people worldwide, and caused 770,000 deaths in 2018.
Without treatment, the average survival time is 11 years, though 1 in 10 remain symptom-free for many years.
Antiretroviral treatment increases life expectancy for those infected.
Bird Flu: H5N1 bird flu spreads through physical contact with infected birds, and if it mutates, it could lead to human-to-human transmission, posing a major global threat to millions of lives.
West Nile Virus: spread by mosquito bites, mainly affects birds, but can infect humans, horses, dogs, and other animals.
Less than 1% of infected people get seriously ill.
It originated in Egypt to Iran, was first detected in the U.S. in 1999, and is controlled by mosquito control.
In humans, it can cause:
Asymptomatic infection (like flu)
West Nile Fever (fever, headache, rash, can last up to two months)
West Nile Meningitis/Encephalitis (severe brain infection, possibly leading to coma or death).
Protozoan Diseases
Malaria
Cause: Four species of Plasmodium (a protozoa).
Spread: By female mosquitoes.
Transmission:
Mosquito bites humans → Plasmodium goes to the liver and bloodstream → malaria develops.
Infected person bitten by another mosquito → Plasmodium passed on.
Death Toll: 1 to 3 million people annually.
—--------------------------------------------------- LECTURE 8 ----------------------------------------------------
1. Food Production & Chemicals
Use of Chemical Fertilizers
Extensive Use of Nitrate Fertilizers
Leads to nitrites in groundwater
Health Effects of Nitrites in Water
Converts hemoglobin into a form that cannot carry oxygen
Causes methemoglobinemia (Blue Baby Syndrome) in infants
Chemical Pesticides
What Are Pesticides?
Chemicals used to kill pests
Active Ingredient → Targets and kills pests
Types of Pesticides
1. Insecticides (Kill Insects)
Natural: Pyrethrum (from chrysanthemum)
Inorganic Compounds
Organochlorine Insecticides (DDT, chlordane, aldrin, dieldrin, heptachlor)
Neurotoxin, low acute toxicity to humans
Persistent and bioaccumulative
Many banned (Stockholm Convention)
Organophosphate Insecticides
Neurotoxin, not persistent in the environment
Toxicity to humans varies
Carbamate Insecticides
Similar to organophosphates
Low acute toxicity to humans
Pyrethroid Insecticides (Synthetic pyrethrum)
Low acute toxicity
Found in some consumer products
2. Herbicides (Kill Plants)
Selective Herbicides → Kill broad-leaved plants, not grass family crops
Military use: Removes enemy cover
Non-Selective Herbicides → Kill all plants
Example: Roundup (Monsanto’s)
Roundup Ready: Genetically engineered soybeans
3. Fungicides → Used in agriculture
4. Rodenticides → Often anticoagulant baits
Limitations of Pesticides
Resistance → Some pests survive and reproduce
Human Health Risks
Difficult to study (changing chemicals, varied exposure)
Acute and Chronic Effects
Neurologic, reproductive effects, cancer
Disparities in Exposure
Workers at risk (farmers, hired laborers)
More hazardous pesticides still in use in low-income countries
2. Transmissible Foodborne Illnesses
Causes: Contaminated meat, dairy, eggs, seafood, fresh produce, improper food handling
Symptoms: Diarrhea, vomiting, fever, abdominal cramps (lasts 1-10 days)
Prevention: Proper food storage, cooking, hygiene
Major Bacteria
E. coli: From unwashed veggies, contaminated meat → diarrhea, kidney failure (HUS)
Complications Hemolytic Uremic Syndrome in which the red blood cells are destroyed and kidneys fail (2-7% of cases)
Clostridium Botulinum (Botulism): Rare but serious (can be fatal) its caused by a nerve toxin, not the bacteria itself
Canned Foods → Must be pressure-cooked at 121°C (250°F) for 3 min
Unusual Sources → Garlic/herbs in oil, baked potatoes in foil, home-canned/fermented fish
Types:
Foodborne (contaminated food)
Wound (infected wounds)
Infant (babies ingest spores)
Symptoms (12–36 hours after ingestion)
Vision Issues → Double/blurred vision
Swallowing Issues → Difficulty swallowing, constipation
Muscle Weakness → Can cause paralysis
Respiratory Failure → Can be deadly
Salmonella: Found in poultry, reptiles, environment, small turtles common source of the illness → flu-like symptoms, long-term arthritis
Listeria monocytogenes: Found in soil, water, plants, sewage, feces; carried by humans & animals without symptoms
Can survive and grow in refrigerated foods; looks, smells, and tastes normal
Killed by proper cooking
Causes listeriosis, dangerous for pregnant women, elderly, and weak immune systems
Severe cases → Brain infection (meningitis, encephalitis), death
Viruses & Parasites
Parasites: Live in hosts, transmitted through feces, animals, humans, undercooked wild game
3. Non-Transmissible Foodborne Illnesses
Shellfish-Associated Toxins: toxins from planktonic algae accumulate in shellfish (mussels, clams, scallops, oysters)
Symptoms depend on toxin type, amount in shellfish, and consumption level
Symptoms: Neurological (numbness, drowsiness, paralysis, memory loss, coma) & Gastrointestinal (nausea, vomiting, diarrhea)
Colour Additives: everywhere, only certified ones allowed
Cancer-causing additives banned
Obesity: overeating, sedentary lifestyle, genetics, hormones, social factors
Risks: Heart disease, diabetes, high blood pressure/cholesterol, sleep apnea, cancer
Diabetes: Type 1: Low insulin levels Type 2: Insulin resistance & low secretion
Prevention: Exercise (2.5+ hrs/week), high fiber/whole grains, low glycemic index foods, moderate fat/alcohol intake
Global Food Sources: 90% of calories from 14 plants & 8 animals
Wheat, rice, corn = half of global calories
Rising income → More meat consumption
Coastal areas rely on fish/shellfish
Poverty & Inequality: Undernutrition, Malnutrition (Vitamin A, iron, iodine deficiency), Overnutrition (obesity)
Organic Food Trend: $35 billion/year industry. Green lifestyle & organic certification (3,670+ farms in Canada)
4. Organic & Genetically Modified Food
Organic Food: Growing industry, focuses on natural farming methods
Genetically Modified Crops (GMCs): Engineered for pest resistance, faster growth
Concerns: Allergies, antibiotic resistance, environmental spread
—--------------------------------------------------- LECTURE 9 ----------------------------------------------------
Transport and Fate
Key Definitions
Transport: Movement of contaminants within/between environmental media.
Fate: Physical, chemical, or biological transformations of contaminants.
Physical-Chemical Properties
Fate & transport depend on volatility, polarity, solubility, oxidation state, molecular weight.
Water-soluble toxins spread through water; fat-soluble toxins (lipophilic) accumulate in fat.
Lipophilic tendency leads to:
Bioaccumulation: Buildup in individual organisms.
Biomagnification: Increase across food chains.
Higher molecular weight chemicals: More persistent, lipophilic, less volatile, less water-soluble.
Persistence: Measured by half-life in air, water, or soil.
Introduction to Toxicology
Toxicology: Study of toxic substances, their effects, fate, and transport in the body.
Key factors: Receptor, Exposure, Dose, Response.
Receptor (Affected Organism)
Human envelope: Body’s boundary with the environment.
Factors affecting response: Age, health, genetics.
Exposure (Contact with Contaminants)
Routes: Ingestion (85%), Inhalation (10%), Skin absorption (5%).
Exposure assessment: Measures dose via area monitoring, personal monitoring, surveys, GIS.
Quantifying Exposure
Dose estimate: Converts exposure into measurable units.
Tools:
Area monitoring: Collects dust samples for lab analysis.
Personal monitoring: Portable air sampling near breathing zone.
Dose units: mg / (kg × day), normalized to body weight & time.
Other exposure data sources:
Questionnaires & diaries
Surrogate measures (indirect indicators of exposure effects).
GIS (Geographic Information Systems) for mapping exposure patterns.
Dose (Amount Taken In)
Acute dose: Single, high exposure.
Chronic dose: Continuous low exposure over time.
Absorbed dose: Amount entering body.
Biologically effective dose: Amount interacting with tissues.
Chemical interactions:
Antagonistic (reduces effect)
Synergistic (enhances effect)
Toxicokinetics (Movement in the Body)
Body burden: Total toxicant in body.
Processes: Absorption, distribution, metabolism, storage, excretion.
Toxicodynamics (Effects on the Body)
Nonspecific effects: Burns, narcosis (temporary sensory depression).
Specific effects: Organ damage, reproductive harm, mutagenesis, carcinogenesis.
Dose-Response Relationship
Paracelsus’ Principle: “The dose makes the poison.”
Graph: Dose (x-axis) vs. Response (y-axis).
Toxicity testing:
Chronic rodent bioassays (2 years).
Key dose levels:
NOAEL (No Observed Adverse Effect Level).
LOAEL (Lowest Observed Adverse Effect Level).
LD50: Lethal dose for 50% of test subjects.
Other Toxicity Testing Methods
Case reports, epidemiological studies, computer simulations, tissue cultures.
Biomarkers: Hormone changes, protein markers, enzyme induction.
—-------------------------------------------------- LECTURE 10 ----------------------------------------------------
Risk
Risk: The probability of suffering from a hazard.
Risk Assessment
Why it’s needed: Sometimes action must be taken before full scientific understanding is reached.
Steps:
Exposure and Toxicity are evaluated to estimate health risk.
Benefits of Risk Assessment
Identify agents causing diseases.
Test new chemicals.
Help rank risks and eliminate or reduce some.
Quantitative data for decision-making.
Risk Assessment Stages
Problem Definition: Goals, policies, and hazard definition.
Identify Contaminant: Single or complex compounds, contaminated areas.
Receptor Analysis: Who or what is exposed (human, species). Sensitive groups like children.
Pathways Analysis: How contaminants reach receptors (air, water, food, etc.).
Exposure Assessment:
(1) Multiple Routes of Exposure
Exposure sources:
Air (indoor/outdoor)
Water (drinking, showering)
Soil
Sediments
Diet (various foods)
Other sources (e.g., dermal contact)
(2) Exposure Formula
Exposure (g/day) = Concentration × Intake Rate
Total exposure = Exposure from food + air + skin + etc.
(3) Estimated Daily Intake (EDI) = (Concentration × Intake Rate)
EDI = mg/kg body weight / day
Consider routes: air, water, food, skin, etc.
IR: Intake rate (e.g., m³ air/day, kg food/day)
C: Chemical concentration (mg/m³ air, mg/kg food)
B: Bioavailability factor (how much chemical is available for uptake)
EF: Exposure frequency (days/year)
ED: Exposure duration (days)
BW: Body weight (kg)
AT: Averaging time (days)
Example Calculation
Example: A child exposed to contaminated soil 3 days/week for 4 years:
Exposure factor = (3 days/week × 52 weeks/year × 4 years) ÷ (4 years × 365 days/year)
Total EDI = EDI from food + EDI from air + EDI from skin + …
Toxicity and Risk Assessment
Non-Cancer vs. Cancer Effects
Non-cancer effects: Have thresholds (safe dose exists).
Carcinogenicity: No threshold (any dose may cause cancer).
Non-Cancer Hazard Assessment
Exposure assessment: Measure dose (mg/(kg*day)).
Hazard identification: Identify non-cancer effects.
Dose-response assessment:
Use NOAEL and LOAEL from studies.
Derive Reference Dose (RfD): Dose without adverse effects.
RfD = NOAEL/Uncertainty factors.
Risk characterization:
Hazard Quotient = Actual dose / Reference dose.
Hazard Quotient > 1 indicates potential harm.
Carcinogenic Hazard Assessment
No safe dose: Any exposure may cause cancer.
Hazard identification: Use IARC classifications:
Group 1: Carcinogenic to humans.
Group 2A: Probably carcinogenic.
Group 2B: Possibly carcinogenic.
Group 3: Not classifiable.
Group 4: Probably not carcinogenic.
Dose-response assessment:
Derive Cancer Slope Factor.
Risk characterization:
Incremental Lifetime Risk = Exposure × Cancer Slope Factor.
Hazard Quotient > 1 indicates cancer risk.
RMOS (Relative Margin of Safety) = EDI / RsD.
RMOS < 1: Acceptable risk.
RMOS > 1: Unacceptable risk.
Uncertainties: Inaccurate data, measurement errors, difficulty estimating exposure for children, bioavailability challenges, and future predictions.
Critique: Risk assessments work best for carcinogens but have many uncertainties. Assumptions may limit accuracy.
Toxicity & Risk Assessment
Non-cancer risks: Use reference doses (RfD) for safety.
Cancer risks: No safe dose, use cancer slope factor for risk estimation.
Uncertainties in Risk Assessment
Insufficient data, errors, future predictions, and exposure estimation challenges.
Risk Management and Communication
Risk management: Decisions and actions to reduce or eliminate risk.
Risk communication: Informing decision makers and the public about risks and actions taken.
Precautionary Principle
Principle: Take action to prevent harm to health or environment, even if cause-and-effect isn’t fully understood.
Examples: Kyoto Protocol, Montreal Protocol, EU REACH program.
Key Risk Terms
Hazard: Something that can cause harm.
Exposure: Contact with a hazard.
Dose: Amount of chemical absorbed by the body.
Dose-Response Relationship: How dose impacts effect.
—-------------------------------------------------- LECTURE 11 ----------------------------------------------------
Lecture 11a: Environmental Hazards to Specific Populations
1. Children’s Environmental Health
Unique Exposure Patterns:
Higher exposure due to limited diet, behavior, and environment.
Limited Diet:
Eat 3-4x more food per body weight than adults.
Drink more water relative to body weight.
Fewer food varieties but large quantities of specific foods.
Behavioral Risks:
Mouthing objects: 2-6-year-olds touch their mouths 9x per hour.
Risky activities: Swimming, construction sites, sun exposure, smoking (teen smoking rate varies by region).
Environmental Exposure:
Indoors: Dust, pollutants, radon.
Outdoors: Pesticides, skin infections from grass.
Short stature: Children breathe air closer to the ground, while adults breathe 4-6 feet higher.
Spend most time indoors, exposed to dust and pollutants.
Higher metabolic rate: Absorb more through skin and lungs.
Skin absorbs more – thinner, more permeable, higher surface area-to-weight ratio
Digestive system – longer absorption time, larger intestine surface, higher pH (less acidic), absorb more lead
Breathing – take in 2x more air per kg
Brain & organs – more blood flow, organs are bigger for their size
Blood-brain barrier – still developing
Detox systems – less developed (slower breakdown of toxins)
Chronic disease risk – longer time to develop over life
2. Women’s Health and Environment
Reproductive Health: Influence children’s health (bearing/nursing).
Health Risks: Higher risk of breast cancer (hormones, chemicals) and osteoporosis (lead, cadmium).
3. Workers and Noise Hazards
Noise Exposure: Can lead to hearing loss
Tinnitus (ringing in ears), Threshold Shift (can’t hear certain frequencies).
Loss of high freq (≥4000 Hz) first, then low freq (<4000 Hz)
Prevention: Limit exposure to 85 decibels.
Common industries affected: Iron foundries, military, and manufacturing.
Other effects: Cognitive issues, cardiovascular risks.
4. Environmental Noise
Sources: Target shooting, rock music, motorcycles, personal music players
Teen hearing loss in the US: 15% (1988–1994) 20% (2005–2006) 10.9% (2017–2020)
Airport noise linked to poor reading and memory
5. Elderly and Environmental Health
Canada’s aging population is growing fast
More chronic illness and disability from:
Lead exposure
Air pollution (indoor & outdoor)
Waterborne microbes
Pesticides
Lecture 11b: War and the Environment
Environmental Damage:
Nuclear weapons: Radioactive contamination.
Bombing: Destruction of infrastructure, forests, and food sources.
Landmines: Hazardous to people, disrupts ecosystems.
Chemical/Biological Warfare: Poisoning, disease spread, and environmental destruction.
Lecture 11c: Population Growth
Exponential Growth: 1.15% globally (slower in developed countries).
Developed countries 0.1%
Developing countries 1.5%
Birth and Death Rates:
Birth rate = Live births/1000 people.
Death rate = Deaths/1000 people.
Population change = (Births + Immigration) - (Deaths + Emigration).
Factors Affecting Birth & Death Rates:
Birth: Labor force needs, education, women’s rights, healthcare.
Death: Improved food, water, sanitation, and medicine.
Life expectancy: Global increase (67.68 years in 1955 → 73.16 years in 2023).
Environmental Impact of Population Growth:
High consumption stresses natural resources.
Human activity altered 50% of Earth’s surface
Soil and water degradation due to overconsumption.
Environmental Health Problems
Affluenza: Overconsumption in pursuit of happiness.
Solutions: Reduce waste, limit consumption, and protect biodiversity.
—-------------------------------------------------- LECTURE 12 ----------------------------------------------------
Lecture 12a: Climate
Climate: Long-term weather patterns (years).
Climate System: 5 parts:
Atmosphere
Land Surface
Hydrosphere
Biosphere
Cryosphere (snow and ice)
Greenhouse Effect
Energy from the Sun warms Earth's surface.
Heat radiates back, but gases (water vapor, CO2, etc.) trap heat, warming the Earth.
Greenhouse Gasses
Water vapor: Most important greenhouse gas.
CO2, CH4, N2O: Others.
CO2 & Global Temperature
Main Contributors to CO2: Fossil fuels, deforestation, livestock, rice farming, fertilizers.
Top CO2 Emitters: US, China, Russia since 1850.
Processes Affecting Increase of Greenhouse Gases
Fossil Fuels:
Coal (42% for electricity)
Transportation (24%)
Industrial Processes (20%)
Residential/Commercial Uses (14%)
Other Causes:
Deforestation and burning of forests.
Livestock (methane emissions).
Rice farming.
Inorganic fertilizers.
Problems
20th century: Hottest in 1000 years.
Global Temp rise: 0.7°C since 1861.
Melting glaciers and rising sea levels (0.1-0.2m last century).
Global Climate Change
Predicted Temp Rise:
Optimistic: +1.8°C
Pessimistic: +4.0°C
Sea Level Rise:
Optimistic: 0.18-0.38m
Pessimistic: 0.26-0.59m
Human Health Impacts
Higher temps: Spread of diseases, coastal flooding, extreme weather = crop failure, famine.
Northern Europe: Possibility of cooling.
International Efforts
Kyoto Protocol (2005): Agreement to reduce emissions.
US did not sign.
Lecture 12b: Ozone-depleting Chemicals
CFCs (chlorofluorocarbons): Major cause of ozone depletion.
Seemed ideal: non toxic, not flammable or corrosive, and chemically stable
When reach stratosphere, breakdown of O3 → net loss of ozone
Effects:
More UV exposure (skin cancer, cataracts).
Climate change.
Impact on agriculture, wildlife, and materials.
Montreal Protocol (1987): Controls to reduce CFCs.
Ozone recovery expected by mid-21st century.
Lecture 12c: Biodiversity Crisis
Extinction Categories:
Extinct: No longer exists.
Endangered: At risk of extinction.
Vulnerable: Likely to become endangered.
Threatened: Close to becoming endangered.
Current Extinction Rate: At least 100 times higher than before humans.
Extinction Threats
Habitat loss (e.g., wetland loss in Canada).
Disturbance of Earth’s surface (e.g., urbanization).
Human impact: 10-55% of Earth's ecosystems damaged.
Global climate change, ozone depletion, chemical pollution, and acid rain also contribute.
Extinction Threat Examples
Habitat fragmentation: Breaking up habitats into smaller pieces.
Nonnative species: Species introduced by humans that harm ecosystems.
Poaching and hunting: Illegal killing of animals.
Predator control: Killing predators like deer and coyotes to manage populations.
Why Preserve Species?
Ecosystem Stability: Protecting species keeps ecosystems healthy.
Disease Control: Ecosystems can affect the spread of diseases.
Economic Value:
Aspirin: Comes from willow tree.
Taxol: From Pacific Yew tree, used to treat cancer.
Aesthetic & Ethical: Ecotourism and moral duty to protect wildlife.
Research Models for Human Physiology and Diseases
Bears and Sharks are studied to understand human health and diseases.