Chapter 17: Environmental Hazards and

Human HealthKelsey KushnerMegan Stellini

Global HIV/ Aids• Aquired immune deficiency syndrom (AIDS)

o Caused by infection of human immunodeficiency virus (HIV) o Cripples the immune systemo Spread around the world, mostly in African Countrieso No way to cure it -> only help people to live longer

Health Hazards we Face

• Risk are usually expressed as Probabilitieso Risk = the probability of suffering harm from a hazard that can

cause injury, death, disease, economic loss, or damage

5 major types of Hazard: 1. Biological hazard: bacteria, viruses, parasites, protozoa,

and fungi2. Chemical hazard: harmful chemicals in air, water, soil, and

food.3. Physical hazard: fire, earthquake, volcanic eruptions, floods,

and storms4. Cultural Hazard: unsafe working conditions, unsafe

highways, poverty, criminals5. Lifestyle Hazard: smoking, overeating, alcohol, unsafe sex

Disease can Spread• Nontransmissible disease = caused by something

other than a living organism and does not spread from one person to another (asthma, diabetes, malnutrition)

• Infectious Disease = caused when a pathogen such as bacterium invades the body and multiplies in cell and tissue (flu, HIV, malaria)

- Leading cause of Disease in 1900• Transmissible disease = infectious disease that can be

transmitted from one person to another (HIV, flu, measles)

• DALYs – (disability adjusted life years) measure total disease burden in a population

World Health Organization = developing Global Health Atlas which contains database and map based on health statistics in the World

Genetic Resistance

Genetic Resistance to Antibiotics- Lack of preventing disease

because of the reproductive rate of bacteria that allows bacteria to become genetically resistant to an increasing number of antibiotics in natural selection - Spread of Bacteria- Overuse of Pesticides - Overuse of Antibiotics (MRSA)

Animal to Human• Wildlife moves infectious disease to

humans • Ecological medicine = tracking down the connections

between wildlife and humans -> prevent spread of disease o Clearing of forests -> results in movement of animals

such as mosquitoes (Malaria)o Global Warming o Bush Meat trade -> dead animal blood may contain

viruses that are then exposed to humans o Factory meat – E coli bacteria transferred from animals

to humans when consumed

SOULTIONS• WHO (World Health Organization) • Solutions:

o Increase research on tropical diseases and viruses

o Reduce Povertyo Decrease malnutritiono Improve drinking water o Reduce use of unnecessary antibioticso Educate people taking antibioticso Require hand washing

Chemicals cause Cancer

• Toxic chemicals- cause permanent/ temp. harm or death o Carcinogens (chemicals, radiation, or viruses that cause

cancer)

o Mutagens (chemicals, radiation, or viruses that cause mutations)

o Teratogens (chemicals, radiation, or viruses that cause birth defects)

• PBCs o Chlorine containing organic compounds used as

lubricants, hydraulic fluids and electrical insulatorso Banned because cause Liver cancer o Found in water, air, food chain, and soil

Affect our Systems1. Immune System (disease)

- Infectious bacteria, viruses, and protozoa

2. Nervous System (brain, spinal cord, peripheral nerves) - Retardation, ADD, learning disabilities, paralysis,

and death

3. Endocrine System (glands that release hormones)- Learning behavior, growth, sexual reproduction,

development

Mercury• (Hg) is a teratogen and potent neurotoxico Interferes with nervous system o Released into the air from

rocks, soil, volcanoes, and vaporization from ocean (fish)• Brain damage in children• Harm kidneys, heart, and

immune system in adults

Toxicology• The study of the harmful effects of chemicals on

humans and other organismso Study of poisonso Toxicity: a measure of how harmful a substance is (ability to cause

injury, illness, or death)o Harmful if ingested in a large enough quantity

At what level of exposure to a toxic chemical will it cause harm?

o Dose: amount of harmful chemical that a person has ingested, inhaled, or absorbed through skin

o Age (children to adults)o Genetic makeupo Multiple Chemical Sensitivity (MCS)o Solubility and Persistence (resistance to breakdown)o Biological magnification: concentrations of toxins increase through

the trophic levelso Response: damage to health resulting from exposure

• Acute (immediate) or chronic (permanent)

Protecting Children from Toxic Chemicals

• Infants and young children are more susceptibleo 1. breathe more air, drink more water, eat more food per unit of body

weighto 2. exposed to toxins in dust or soil (mouth)o 3. usually have less well-developed immune systems and body

detoxification processes

• EPA (2003) children face a risk 10 times higher than that faced by adults

Estimating Toxicity• Live laboratory animals

o Mammals systems are like humans (small and reproduce quickly)o 2-5 years/hundreds to thousands of test animals/$2 million per

substance test

• Dose-response curve:o lethal doseo Median lethal dose (kill 50% within 18 days)o Nonthreshold dose-response model: any dosage causes harm that

increases with the dosageo Threshold dose-response model: threshold dosage must be

reached before any detectable harmful effects occur

Alternatives to Animal Testing

• Computer simulations• Testing with tissue cultures, chicken egg

membranes, and individual animal cells• High-speed robot testing devices can now

measure the biological activity of more than one million compounds a day to help determine their possible toxic effects

Are Trace Amounts of Toxic Chemicals Harmful?

• Honestly: in most cases we don’t knowo Too little datao Difficulty of determining the effects of low levels of these chemicals

• Argument life expectancy has been increasing in most developed countries for decades

Comparative Risk Analysis (1)

• High risk Health Problemso Indoor/outdoor air pollutiono Worker exposure to industrial/farm chemo Pollutants in drinking watero Pesticide residues on food

• High risk environmental problemso Global climate changeo Stratospheric ozone depletiono Wildlife habitat destruction/alterationo Species extinction/loss of biodiversity

Comparative Risk Analysis (2)

• Medium-risk Ecological Problemso Acid depositiono Pesticideso Airborn toxic chemicalso Toxic chemicals, nutrients, and sediment in surface waters

• Low-risk Ecological Problemso Oil spillso Groundwater pollutiono Radioactive isotopeso Acid runoff to surface waterso Thermal pollution

Poverty, Gender, and Lifestyle

• High death toll resulting from poverty:o Malnutrition, increased susceptibility to normally nonfatal infectious

diseases, and often-fatal infectious diseases transmitted by unsafe drinking water

• AVOID risks like….o Smoking, exposure to smoke, overconsumption of foods containing

cholesterol and saturated fats, drinking more than two glasses of alcohol per day, excess sunlight, unsafe sex

Death From Smoking• World’s most preventable major cause of

suffering and premature death among adults• Kills an average of 14,800 people per day• By 2030, the annual death toll is projected to

reach more than 8 million (average of 21,900 deaths per day)

• Only 1 in 10 people succeed in quiting• Passive Smoking: second-hand smoke

o Children more likely to develop allergies/asthmao In 2006, CDC estimated 3,000 lung cancer deaths and 46,000 heart

disease caused by second-hand smoke

Encouraging News• Average # of cigs smoked per person in the US

declined by 56% between 1976 and 2006• Dropped globally by 16% between 1988 and 2006

How People Evaluate Risks

• 1. Fear• 2. The Degree of control we have• 3. Whether a risk is catastrophic, not chronic• 4. Optimism bias (same risks don’t apply to them)• 5. Instant gratification (fake tanning)

How to ACTUALLY Evaluate Risks

• 1. Compare risks• 2. How much risk are you willing to accept?• 3. Determine the actual risk involved• 4. Concentrate on evaluation and carefully

making important lifestyle choices