Environmental Health, Pollution and Toxicology Unit 5: AP Environmental Science (Chapter 15)

If it’s natural, does that mean it’s always good? Disease results from an imbalance between an organism and it’s environment The same things that can cause disease can be beneficial to an organism Environmental factors determine the prevalence and diversity of disease infections

What determines your chances of getting a disease? Physical Environment Biological Environment Lifestyle Genetics

Terminology Morbidity: having a disease Mortality: death Pathogen: disease causing organism Vector: transport system for pathogens

Terminology Pollution: introduces harmful materials or produces harmful conditions to the environment - introduced through a) Point Sources b) Area Sources (Non-point) c) Mobile Sources d) Fugitive Sources Contamination: making something unfit for a particular use through the introduction of desirable material

Terminology Toxicology: the science that studies chemicals that should be toxic Carcinogen: a type of toxin that increases the risk of cancer Malignant, Benign, Metastasis Synergism: the interaction of different substances resulting in a total effect greater than the sum of the effects of the separate sources (multiplies effect) Antagonistic interactions reduce effects

Measuring Pollutants Measuring depends on the substance Common Units - can be mass/mass; or mass/volume etc. Make sure you are comparing similar units ppm: Parts per million ppb: Parts per billion Micrograms per cubic meter (measures air)

Categories of Pollutants Infectious Agents, called pathogens –spread through the interactions between people, food, air, water, soil Allergens; infectious bacteria, protozoans, viruses (Examples: Legionnaires disease; salmonella; Anthrax, e-coli, cholera) Toxic Heavy Metals – metals with high atomic weights Body Burden – amount of metal we have in our body (Examples: Mercury, Cadmium, Nickel, Lead, Arsenic, Selenium)

Categories of Pollutants Additional Pollutant Sources: Radiation Thermal Pollution Particulates Asbestos Electromagnetic Fields Noise Pollution Voluntary Exposure

Toxic Heavy Metals Travel through toxic pathways (Atmosphere  land  water  sediment) Biomagnification: the accumulation or increase in concentration of a substance in living tissue as it moves through a food web.

Toxic Pathway for Mercury

Organic Compounds Composed of carbon Synthetic Organic Compounds: used in industrial processes Use in: pharmaceuticals, food additives, pest control Over 20 million produced New ones appearing at about 1 million per year

Organic Compounds Persistent Organic Pollutants: Synthetic organic compounds often containing chlorine developed in higher numbers around the same time as the Green Revolution Do not break down easily Soluble in fat (allowing them to be absorbed in living tissue) Easily transported by wind, water or sediments Examples: Aldrin, DDT, PCB’s, Dioxins

Organic Compounds Hormonally Active Agents: Chemicals in the environment able to cause reproductive and developmental abnormalities in animals

Thermal Pollution Occurs when heat released into water or air produces undesirable effects Major heat pollution sources are electrical power plants that use steam generators Warm water holds less oxygen

Asbestos Set of six minerals that form small, fibrous strands Used in fire prevention and insulation Dangerous carcinogen if inhaled

Electromagnetic Fields Magnetic fields transmitted by electric motors, transmission lines for utilities, and electrical appliances Strength of fields decreases with distance Some studies show an increased risk, especially in children, of developing cancer with higher exposure to magnetic fields(1.5-3x higher than low exposures)

Voluntary Exposure Personal choice to consumer or interact with toxic material knowing the risks involved Smoking Drinking Substance abuse Job hazards Habitat

General Effects of Pollutants Changes in Abundance Changes in Distribution Changes in Birth Rates Changes in Death Rates Changes in Growth Rates “All substances are poisons: there is none which is not a poison. The right dose differentiates a poison and a remedy." Paracelsus ( )

General Effects of Pollutants There are 500 synthetic organic chemicals in our body burden today that did not exist before 1920 Environmental factors like malnutrition, smoking, cooking fires, skin cancer, exposure to chemicals contribute to 40% of the world’s annual deaths TIME RISK Modern Traditional

Worldwide Diseases 1.Acute Respiratory Infection Deaths 3.9 million/year, 2.5 million children 2.AIDS 3 million/year, most are young adults 3.Diarrheal Diseases 2.1 million/year, 1.9 million/year under the age of 5 4.Tuberculosis 1.6 million/year 5.Malaria1 million/year 6.Hepatitis B1 million/year 7.Measles800,000/year, mostly under the age of 5 and increasing Anti-viral drugs are widely used although few are effective and there are high chances of side effects. Vaccines are still the best method of treatment for viral diseases.

Worldwide Cases of Death SourceAnnual Deaths Poverty/Malnutrition10 million Tobacco4 million Pneumonia/Flu3.9 million Air Pollution3 million AIDS3 million Diarrheal2.1 million Tuberculosis1.6 million Malaria1.1 million Work Related1.1 million Hepatitis B1 million

Chemical Hazards A toxic chemical can cause temporary or permanent harm or death. Mutagens are chemicals or forms of radiation that cause or increase the frequency of mutations in DNA. Teratogens are chemicals that cause harm or birth defects to a fetus or embryo. Carcinogens are chemicals or types of radiation that can cause or promote cancer.

Disease Sources Carcinogen SourcePercentage of all cancers Smoking30-40% Diet20-30% Occupational Exposures10-20% Inherited Genetics10-20% In general transmissible diseases have dropped since the 1950’s but non-transmissible diseases have risen

Chemical Hazards A hazardous chemical can harm humans or other animals because it: Is flammable Is explosive An irritant Interferes with oxygen uptake Induce allergic reactions.

Chemical Hazards Long-term exposure to some chemicals at low doses may disrupt the body’s : Immune system: specialized cells and tissues that protect the body against disease and harmful substances. Nervous system: brain, spinal cord, and peripheral nerves. Endocrine system: complex network of glands that release minute amounts of hormones into the bloodstream.

Chemical Hazards Individual cells have enzymes to repair damaged DNA and protein Some cells grow fast enough to replace damaged cells while other have a longer lifespan that would not repair the damage before negative effects set in

Chemical Hazards Molecules of certain synthetic chemicals have shapes similar to those of natural hormones and can adversely affect the endocrine system.

Concept of Dose and Response The effect of a certain chemical on an individual depends on the dose Individuals differ in their response to chemicals Threshold Effects: - the level below which effects are not observable and above which effects become apparent Therapeutic Index: - ratio of the amount of a substance that is effective compared to the amount that becomes toxic (LD-50 : ED-50)

Dose and Response Curve

ED-50 Effective Dose 50%: amount of a substance to produce a specific effect on 50% of a test sample of organisms. (This can be a toxic or non-toxic effect) TD-50 Toxic Dose 50%:the dose that produces a toxic effect in 50% of the population LD-50: Lethal Dose 50%: dose of toxin it takes to kill 50% of the organisms

Dose and Response Curve

Ecological Gradients Changes in vegetation with distance from a toxic source. Tolerance: The ability to resist or withstand stress resulting from exposure to a pollutant or harmful condition Behavioral tolerance teaches avoidance of the stress Physiological tolerance comes from adaptation to the stress or a genetic resistance to stresses caused by a pollutant

Ecological Gradients Acute and Chronic Effects Acute – occurs soon after exposure to large doses Chronic - occur over extended periods of time, usually from low doses of exposure

Effects of Exposure Factors determining the harm caused by exposure to a chemical include: The amount of exposure (dose). The frequency of exposure. The person who is exposed. The effectiveness of the body’s detoxification systems. One’s genetic makeup.

Risk Assessment Risk – the possibility for harm (Exposure x Harm) Calculating this risk is called Risk Assessment 4 steps 1. Identification of the hazard 2. Dose-Response assessment 3. Exposure assessment 4. Risk characterization

United States Hazard Effects HazardShortens Life Span By: Poverty7-10 years Born male7-5 years Smoking6 years Overweight (by 35%)6 years Single5 years Overweight (by 15%)2 years Spouse that smokes1 year Driving7 months Air pollution5 months Alcohol5 months Drug abuse4 months Flu4 months AIDS3 months

Risk Assessment Under existing laws, most chemicals are considered innocent until proven guilty, and estimating their toxicity is difficult, uncertain, and expensive. Federal and state governments do not regulate about 99.5% of the commercially used chemicals in the U.S.

Risk Assessment The U.S. Environmental Protection Agency proposed that regulators should assume children have 10 times the exposure risk of adults to cancer-causing chemicals. Some health scientists contend that regulators should assume a risk 100 times that of adults.

Risk Assessment Children are more susceptible to the effects of toxic substances because: Children breathe more air, drink more water, and eat more food per unit of body weight than adults. They are exposed to toxins when they put their fingers or other objects in their mouths. Children usually have less well-developed immune systems and detoxification processes than adults.

Precautionary Principle The idea that in spite of the fact that full scientific certainty is often not available to prove cause and effect, we should still take cost-effective precautions to solve environmental problems where there exists a threat of potentially serious and/ or irreversible environmental damage Manufacturers contend that wide-spread application of the precautionary principle would make it too expensive to introduce new chemicals and technologies.

Becoming Better at Risk Analysis Risk AssessmentRisk Management Hazard identification Comparative risk analysis What is the hazard? How does it compare with other risks? How much should it be reduced? Risk reduction Probability of risk How likely is the event? Risk reduction strategy How will the risk be reduced? Consequences of risk Financial commitment What is the likely damage? How much money should be spent?

What is the good news? 99.1% of people each year do not die