Environmental Health and Toxicology


Disease- a change in health for the __________ caused by a number of possible factors.

Illness Factors include diet and nutrition, infectious agents, toxic chemicals, physical factors and ______________ stress.

  • Pathogens- Disease causing organisms, such as bacteria, _________, microorganisms or other parasites.

Antibodies are introduced to prevent disease, by introducing a foreign particle

Morbidity- _________
Mortality- death

The Top Three Leading killers worldwide

    1. Cardiovascular Disease
    2. _________ and Tumors
    3. Infectious and Parasitic diseases (24%)


Toxic chemicals

Hazardous = __________, including flammables, explosives, irritants, sensitizers, acids and caustics

Toxins = poisonous- so damaging that they damage living organisms by _________ cells

Allergens = substances that activate the ___________ system, can act directly as antigens and cause an immune response ex. formaldehyde

Levels of Toxicity

Acute Toxicity occurs when a large dose inflicts ____________ harm on an organism

Chronic Toxicity occurs when a __________ dose is expressed over a long period of time, harder to detect because it may not be seen for ________

Chemical Synergism- when two toxins __________ have a greater effect than the SUM of the effects of the two toxins separately ...example/ small amount of alcohol with small amount of _____________ can have a severe effect on the central nervous system...or smoking and ___________ can expose a person to cancer ten times greater than if they were exposed to just one of the factors.

Four Main Categories of TOXINS

  1. ____________- kill neurons in the nervous system quickly ...example Mercury and Lead, DDT, organophosphates
  2. Mutagens- chemicals and radiation that cause ___________ by altering DNA. can trigger cancer and is inheritable if in reproductive cells. no safe level.
  3. Carcinogens- substances that cause _________ ex. pesticides, smoking

    The Delaney Clause to the US Food and Drug Act states that no known carcinogen causing "reasonable harm" may be added to food and drugs.

    1:2 males (mostly ________) and 1:3 females (mostly lung and ________) in US have cancer

  4. Teratogens- toxins that cause abnormal embryonic cell division and result in ________ defects ...example alcohol (fetal alcohol syndrome) and thalidomide (sedative causing abnormal fetal development)

Diet has a huge impact on your health. Eat real food, not too much, mostly plants.


Measuring Toxicity

The ______/Response Curves- a graph that shows the dosage that causes death in a population of organisms as the dosage level of a toxin is increased.

The amount of drug or toxin is plotted on the x-axis and is scaled as a logarithm of dose and the response to the dose is on the y-axis as in expressed in percentage dead.

Not always symmetrical, making it difficult to compare toxicity of unlike chemicals

LD50- measures toxicity of a chemical, LD50 is the dose lethal to _____% of a test population; the lower the LD50, the more toxic the chemical

  • The established dose curve will determine the dose below which none of the test subjects were harmed.
  • The threshold dose is the level at which a negative effect is just starting to occur as the toxin level increases.

Bio______________ of a toxin occurs when an organism absorbs and stores the toxin in its tissues. However, the toxin does NOT accumulate or build up over time from one organisms eating another.

Biomagnification when the toxin becomes increasingly more concentrated higher up the ___________ chain. Animals at the top of the food chain suffer greater harm than those at a lower level. The best-known examples are the insecticide DDT and mercury.


Risk Assessment

  • Calculating the risk of becoming ill when exposed to a toxin or pathogen
    • Risk assessment is the objective estimate of risk.
      • High Risk- ex. smoking or driving while intoxicated
      • Low Risk- ex. infrequent events such as an earthquake
      • Very Low Risk- events that have never been recorded in written history ex. asteroid impact on Earth
      • Mixed Risk- outcomes that are more risking depending on situation ex. living in an area with a high background of cancer cases
    • Risk management is deciding what to do about the risk.
  • Many public health decisions are based on our risk of becoming ill


Famous Cases

"Silent Spring" written by Rachel Carson explored the persistence of _______ pesticides in the environment, biomagnification and effect on non-target species

Other cases include Bhopal, Chernobyl, Minamata, Three Mile Island, Fukushima Nuclear Crisis, Kuwaiti Oil Fires, and the Deep Water Horizon Oil Spill


HAZMAT (Hazardous Materials) Alternatives in the home- You can replace your everyday cleaner with the right combination of harmless substances ...things such as ________ Juice, Vinegar, Water, _______ Soda to make your home safer