Environmental Science Unit 5

Risk

Probability of harm from a hazard

Risk Assessment

Evaluating likelihood and severity of harm

Infectious Disease

Disease caused by pathogens

Transmissible Disease

Can spread person to person

Non transmissible Disease

Cannot spread person to person

Toxic Chemical

Chemical that causes harm to organisms

Carcinogens

Substances that cause cancer

Toxicology

Study of effects of toxic substances

Toxicity

Degree to which a substance is harmful

Dose

Amount of exposure to a substance

Response

Reaction of an organism to a dose

LD50

Dose lethal to 50% of test organisms

LC50

Concentration lethal to 50% of organisms

NOEC

Highest concentration with no observed effect

LOEC

Lowest concentration with observed effect

Precautionary Principle

Prevent harm when effects are uncertain

Five major types of hazards to humans

1. Chemical

2. Biological

3. Physical

4. Cultural

5. Lifestyle

Why deaths from infectious disease dropped

1. Vaccines

2. Sanitatation

3. Clean water

4. Antibiotics

Viruses that are major killers

1. Influenza

2. HIV

3. Covid - 19

4. Hepatitis

5. Ebola

How humans and animals spread diseases

Zoonotic transfer vis contact, food, or vectors

Top five toxic chemicals

1. Lead

2. Mercury

3. Asbestos

4. Arsenic

5. Pesticides

Problems with plastics

Leach chemicals, hormone disruption, micro plastics

How plastics impact human health

microplastics and chemical additives causing reproductive, digestive, metabolic, and cardiovascular issues

Why dose affects people differently

Age, body size, genetics, health, exposure time

Why children are more susceptible to dose

Developing organs, higher intake per body weight

acute effects

Short term exposure effects

Chronic effects

Long term repeated exposure effects

How to identify LD50 on a graph

Point where 50% of organisms die

Primary Pollutants

Released directly into air

Secondary pollutants

Form in atmosphere from reactions

Temperature inversion

Warm air traps cooler polluted air

Acid deposition

The transfer of acidic substances from the atmosphere to the surface

Industrial smog

Coal burning, sulfur based smog

Photochemical smog

Sun + car emissions (ozone)

Natural air pollutants

Volcanoes, dust, wildfires, pollen

Human caused air pollutants

Vehicles, factories, power plants

Factors affecting pollutants buildup

Wind, weather, geography, inversions

Effects of acid rain

Damages buildings, harms forests and lakes

Pollution in developing countries

More indoor/industrial pollution

Why developing countries have more pollution

Fewer regulations, older technology

Most dangerous indoor air pollutants

Radon, mold, CO, tobacco smoke, VOCs

Ways to improve indoor air quality

Ventilation, air filters, reduce chemicals

Point sources

Single identifiable pollution source

Non point sources

Diffuse sources like runoff

Eutrophication

Excess nutrients cause algal blooms

Safe drinking water act

Protects drinking water quality

Clean water act

Regulates surface water pollution

Why non point sources are harder to control

Spread out and hard to trace

Largest causes of water pollution

Agriculture runoff, sewage, industry

Effects of water pollution on waterways

Low oxygen, fish kills, dead zones

Sources of ocean pollution

Plastics, oil spills, runoff, sewage

Impacts of ocean pollution

Wildlife death, bio accumulation

How developing countries purify water

Boiling, filtration, chlorination