APES

Catherine de Medici Mother of Toxicology

Categories of pollution

• Infectious Agents• Transmissible disease: spread from

person to person– Pathogen: infectious agent spread by

air, water, food, body fluids or insects (insects are called vectors when they carry disease)

• Pathogens can be bacteria or viruses

Worlds 8 most deadly diseases

» Acute respiratory infections (pneumonia, influenza, whooping cough)

Diarrheal diseases (dysentery, cholera, etc.)

Tuberculosis

Malaria

AIDS

Measles

Hepatitis B

Tetanus

Epidemiology

• The study of disease in human populations—how and where they occur and how they can be controlled

• Often involves studying large groups over long periods

• Can determine statistical associations between health hazards and effects, but can’t prove the hazards actually caused the effects

Lesson 9.1 An Overview of Environmental Health

Emerging Diseases• Diseases appearing in the human population for the first time or

suddenly beginning to spread rapidly

• Humans have little or no resistance, and no vaccines have been developed.

• Facilitated by increasing human mobility, growing antibiotic resistance, and environmental changes

Lesson 9.2 Biological and Social Hazards

Emergent Diseases

• New Diseases like Ebola, since 1973 there have been 28

Responding to Emerging Diseases

• World Health Organization (WHO): Monitors health events worldwide and coordinates international responses to emerging diseases

• Centers for Disease Control and Prevention (CDC): Responds to emerging diseases in the United States; the CDC developed pandemic plans to deal with the spread of the H1N1 flu virus.

Lesson 9.2 Biological and Social Hazards

H1N1 Virus

Factors that affect the spread of diseases

» Travel, migration, deforestation, climate change, loss of biodiversity, agriculture, urbanization, & nature disasters

It sure is nice to get away from the colon for

awhile

Types of Environmental Health Hazards

• Biological: Viruses, bacteria, and other organisms that cause disease

• Social: Lifestyle choices that endanger health

• Chemical: Harmful artificial and natural chemicals in the environment

• Physical: Natural disasters and ongoing natural phenomena, such as UV radiation, that can cause health problems

Lesson 9.1 An Overview of Environmental Health

Social HazardsLesson 9.2 Biological and Social Hazards

• Some social hazards are easier to avoid than others.

• Examples of social hazards include smoking, being exposed to secondhand smoke, living near an old toxic waste site, working with harmful chemicals, and eating fatty foods.

Toxicology

• Study of poisons: which are substances that cause harmful effects to living things

• Toxin: poison produced by living things• Toxicant: poison manufactured by us• Toxicity: ability of a substance to cause harm

Toxicology

• The study of how poisonous substances affect an organism’s health

• Toxicity is a measure of how harmful a substance is.

• Toxicologists look at toxicity by determining dose-response relationships.

Lesson 9.1 An Overview of Environmental Health

Dose response curve

• Threshold Level- the lowest concentration that could cause a lethal effect

• Variability among people who are exposed to a toxin can influence response so we use LD50

• LD50=lethal dose 50- the dose that kills 50% of the organisms tested- only for dermal and oral ingestion

• LC50-lethal concentration 50-for inhalation• Only for acute effects

Threshold dose

• The dosage at which the negative effect occurs

Poison

• Any substance that has an LD50 of 50mg or less per kg of body weight

Exposure

• Dose: actual amount of a chemical that enters and reacts with our body systems over time

• Exposure: amount of toxic chemical our body comes in contact with

• Absorption: ability of a chemical to find its way into our bloodstream

Routes of Exposure

• Inhalation: thru lungs• Dermal absorption:

thru skin• Oral: thru digestive

system• Injection: enters

directly into veins

Acute

• Short term exposure• Effects occur immediately after exposure• Often reversible• Can be minor or severe• Relationship between exposure and effect

is usually obvious• Knowledge is based on human exposure

Chronic

• Occurs over time• Low exposure over long period• Many effects not reversible• Chronic effects still unknown for many

chemicals• Difficult to establish a link between cause

and effect• Knowledge based on animal studies

Types of Effects

• Local effect: causes damage only where it touches • Systemic: gets into bloodstream and effects many

organs• Bioaccumulation: toxin builds up in body systems

over time• Antagonism: one substance interferes with the

action of another• Synergism: the interaction of two or more chemical

is greater than the sum of their parts

Lesson 9.3 Toxic Substances in the Environment

Chemicals are all around us, and all of them can be harmful to our health in large enough amounts. In other words, “The

dose makes the poison.”

Chemicals are all around us, and all of them can be harmful to our health in large enough amounts. In other words, “The

dose makes the poison.”

Chemical Hazards

• Any chemical can be harmful in large enough amounts.

• A pollutant is something released into the environment that has some harmful impact on people and other organisms.

• Chemical hazards are not necessarily pollutants, and pollutants are not necessarily chemical hazards.

Lesson 9.3 Toxic Substances in the Environment

Oil Pollution

Sick Building Syndrome

• When the majority of a building’s occupants experience certain symptoms for which no other cause can be identified– Irritation of eyes, nose, throat,– Headaches, dizziness– Skin irritation, nausea, vomiting

Toxic Heavy Metals:

• mercury, lead, cadmium, nickel, gold, arsenic, chromium, platinum, selenium, vanadium

• Heavy metals bioaccumulate (biomagnifications), which means they are stored in animals’ tissues as they accumulate more through the food chain. The top carnivores end up with the most in their blood stream.

Bioaccumulation and Biomagnification

• Bioaccumulation: The buildup of toxic substances in the bodies of organisms

• Biomagnification: The increased concentration of toxic substances with each step in a food chain

• Persistent organic pollutants are biomagnified and stay in the environment for long periods of time and over long distances.

Lesson 9.3 Toxic Substances in the Environment

Organic Compounds

• (a.) 4 million different ones (b.) Pesticides, industrial processes, & other consumer products

• (c. ) Dioxin (from burning plastic), PCB’s – electrical industry, oils.

Indoor Chemical Hazards

Lesson 9.3 Toxic Substances in the Environment

Indoor Air Pollutants

• Asbestos-increased risk of lung cancer, mesothelioma• Benzene• Chloroform• Radon-radioactive gas, lung cancer• Formaldehyde-found in carpets, furniture• Lead• Mercury• Nickel• Perchloroehtylene (dry-cleaning chemical)• **all can damage immune system and cause neurological,

reproductive, developmental, and respiratory problems

Sick Building Syndrome

• When the majority of a building’s occupants experience certain symptoms for which no other cause can be identified– Irritation of eyes, nose, throat,– Headaches, dizziness– Skin irritation, nausea, vomiting

Types of Chemical Hazards• Carcinogens: Cancer-causing chemicals

• Chemical mutagens: Chemicals that cause genetic mutations

• Teratogens: Chemicals that harm embryos and fetuses

• Neurotoxins: Chemicals that affect the nervous system

• Endocrine disruptors: Chemicals that interfere with the endocrine system

• Allergens: Chemicals that over-activate the immune system

Lesson 9.3 Toxic Substances in the Environment

Dust mite protein is a common allergen.

Carcinogenicity- the tendency to cause cancer

• Cancer: uncontrolled growth and spread of abnormal cells

• Malignant: tumor invades surrounding tissue• Benign: well defined tumor that does not spread

Teratogen

• Causes birth defects

Carcinogen

• Agent that • causes cancer

Mutagen

• Causes changes in the genetic make-up of cells that can be passed to future generations

Risk Assessment

• Risk: The probability that a hazard will cause harm

• Risk assessment: The process of measuring risk

• Takes into account:• The type of hazard• How frequently humans will

be exposed to it• How sensitive people are to it

Lesson 9.1 An Overview of Environmental Health

Risk Analysis

• A. Estimating Risks» Risk Assessment: identifying hazards and evaluating

their risks, this includes determining what types of hazards are involved, estimating the probability it will happen and estimating how many people it will effect.

» comparative risk analysis: ranking risks» risk management: making decisions about reducing

risks» risk communication: informing the public

• . Risk Benefit Analysis: do the risks outweigh the benefits. The problem with this is that people who decide usually have economic ties to the decision.

Greatest Risks People face

• 1. poverty • 2. being born male • 3. smoking • 4. being 35%

overweight