Unit 10: Environmental Health and ToxicologySECTION 1: RISKS AND HAZARDS

Central Case Study: Poison in the Bottle

● Bisphenol A (BPA) – Used to make hard plastic found in utensils, baby bottles, laptops, toys, etc.

● Leaches into food, water, air, and human bodies

● 93% of Americans currently have it in their body

● Only a low dose required to have negative effects

● Linked to Cancer, nerve damage, and miscarriages

● Mimics the hormone estrogen

● Conflicting information regarding health risk

● Many countries banned use in baby bottles

● U.S. FDA rejected a ban on its use in 2012

RISKS AND HAZARDS

● Risk is a measure of the likelihood that you will suffer harm from a hazard.

● We can suffer from:

● Biological hazards: from more than 1,400 pathogens.

● Chemical hazards: in air, water, soil, and food.

● Physical hazards: such as fire, earthquake, volcanic eruption…

● Cultural hazards: (lifestyle choices) such as smoking, poor diet, unsafe sex, drugs, unsafe working conditions, and poverty.

BIOLOGICAL HAZARDS

● Diseases not caused by living organisms cannot spread from one person to another (nontransmissible disease), while those caused by living organisms such as bacteria and viruses can spread from person to person (transmissible or infectious)

● Bacteria: single-celled, prokaryotic organisms

● Notable bacterial diseases: cholera, Tuberculosis, bubonic plague, anthrax, food poisoning, gonorrhea, strep throat, etc.

● Viruses: small, infectious agent that replicates itself using the living cells of other organisms

● Notable viral diseases: common cold, small pox, Ebola, influenza, rabies, measles, HIV, herpes

BIOLOGICAL HAZARDS

● Antibiotics used against bacteria (antivirals CAN work against viruses, but usually do not)

● Bacteria are developing genetic resistance to antibiotics

● We are starting to see “superbugs” in different bacterial species

Transmissible Disease

● Pathway for infectious disease in humans.

Transmissible Disease

● WHO estimates that each year the world’s seven deadliest infections kill 13.6 million people – most of them the poor in developing countries.

The Growing Global Threat from Tuberculosis

● The highly infectious tuberculosis (TB) kills 1.7 million people per year and could kill 25 million people 2020.

● Recent increases in TB are due to:

● Lack of TB screening and control programs especially in developing countries due to expenses.

● Genetic resistance to the most effective antibiotics.

VIRAL DISEASES

● Flu, HIV, and hepatitis B viruses infect and kill many more people each year then highly publicized West Nile, SARS, and Ebola viruses.

● The influenza virus is the biggest killer virus worldwide.

● Pigs, chickens, ducks, and geese are the major reservoirs of flu.

● As they move from one species to another, they can mutate and exchange genetic material with other viruses.

VIRAL DISEASES

● HIV is the second biggest killer virus worldwide. Five major priorities to slow the spread of the disease are:

● Quickly reduce the number of new infections to prevent further spread.

● Concentrate on groups in a society that are likely to spread the disease.

● Provide free HIV testing and pressure people to get tested.

● Implement educational programs.

● Provide free or low-cost drugs to slow disease progress.

Malaria – Death by Mosquito

● Malaria kills about 2 million people per year

● Caused by parasitic protozoans

● Get into blood stream and cause cells to burst

● Major problem in tropical regions

Preparation for LD

50 Lab – Friday

PRACTICE IN PERFORMING A SERIAL DILUTION

Pre Lab Definitions: (Fill these in on your lab paper)

● Serial: In a series, order or interval. Measured steps.

● Dilution: Water down

● Pipette: “Little pipe” for moving and measuring liquids.

● Serial dilutions reduce the concentration of a sample in small steps or fractions.

Lab: Fill in the instructions as we go along. Read each step carefully.

1. Label test tubes 1, 2, 3, 4.

Lab: Fill in the instructions as we go along. Read each step carefully.

1. Add 10 mL of water to test tube 1.

2. Add 3 drops of methylene blue to test tube 1. (mix) – use paper towel over mouth of tube as methylene blue WILL dye your skin

3. Transfer 1 mL of water from test tube 1 to test tube 2.

Lab: Fill in the instructions as we go along. Read each step carefully.

4. Add 9 mL of water

5. Pipette 1 mL of water from test tube 2 to test tube 3.

6. Add 9 mL of water

7. Pipette 1 mL of water from test tube 3 to test tube 4.

8. Add 9 mL of water

The Basics of Toxicology

● Toxicology – the science that examines effects of poisonous substances

● Toxicity – the degree of harm a substance can inflict

● Toxicant – poison; toxic substance

● Environmental toxicology – deals with toxic substances that come from or are discharged into the environment

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.

Effects of Chemicals on the Immune, Nervous, and Endocrine Systems

● 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 hormones into the bloodstream; help regulate the body.

Dose-Response Studies

• LD50- lethal dose that kills 50% of the individuals

• ED50- effective dose that causes 50% of the animals to display the nonlethal effect

Synergistic Interactions

⬜ Sometimes, when a person is exposed to more that one risk at a time, the risk can compound and become worse

⬜ Ex: the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.

Case Study: A Black Day in Bhopal, India

● The world’s worst industrial accident occurred in 1984 at a pesticide plant in Bhopal, India.

● An explosion at Union Carbide pesticide plant in an underground storage tank released a large quantity of highly toxic methyl isocyanate (MIC) gas.

● 15,000-22,000 people died

● Indian officials claim that simple upgrades could have prevented the tragedy.

Stockholm Convention

⬜ In 2001, a group of 127 nations gathered in Stockholm, Sweden, to reach an agreement on restricting the global use of some chemicals

⬜ 12 chemicals were to be banned, phased out, or reduced

⬜ These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes.

TOXICOLOGY: ASSESSING CHEMICAL HAZARDS

● 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.

Cause of death Annual deaths

Poverty/malnutrition/ disease cycle

11 million (75)

Tobacco 5 million (34)Pneumonia and flu 3.2 million (22)

Air pollution 3 million (21)HIV/AIDS

Malaria 2 million (14)Diarrhea 1.9 million (13)

Tuberculosis 1.7 million (12)Car accidents 1.2 million (8)

Work-related injury & disease 1.1 million (8)

Hepatitis B 1 million (7)Measles 800,000 (5)

3 million (21)

Shortens average life span in the U.S. byHazard

PovertyBorn male

SmokingOverweight (35%)

Unmarried 5 yearsOverweight (15%) 2 yearsSpouse smoking 1 year

Driving 7 monthsAir pollution 5 months

Alcohol 5 monthsDrug abuse 4 months

Flu 4 monthsAIDS 3 months

Drowning 1 monthPesticides 1 month

Fire 1 monthNatural radiation 8 days

Medical X rays 5 daysOral contraceptives 5 days

Toxic waste 4 daysFlying 1 day

Hurricanes, tornadoes 1 dayLifetime near nuclear plant 10 hours

6 years6–10 years

7.5 years7–10 years