Chapter 2 Using Science to Address Environmental Problems

Super Topic 1: The Scientific Method *Never PROVES anything, only removes INCORRECT POSSIBILITIES 1.Recognize Question 2.Research what is already known 3.Develop a hypothesis to explain problem 4.Design & Perform a testable experiment 5.Analyze & Interpret data 6.Reach conclusions & report own data

Super Topic 2: Experimental Controls 1.Variable: a FACTOR that influences a process a.Independent : WHAT YOU’RE TESTING EFFECTS OF b.Dependent: WHAT IS BEING MEASURED (the results) c.Controls: WHAT REMAINS CONSTANT 2.Groups: a.Control: variable that is NOT ALTERED b.Experimental: Independent variable is ALTERED IN A KNOWN WAY

Super Topic 3: Types of Reasoning 1.Inductive Reasoning: SPECIFIC TO GENERAL a.Asks, “What does the grouped information have in common?” b.Can produce NEW KNOWLEDGE, but is prone to ERROR c.Ex. “Gold is a metal that is heavier than water Iron is a metal that is heavier than water Silver is a metal that is heavier than water.” Conclusion: All metals are heavier than water.

Super Topic 3: Types of Reasoning (cont.) 2. Deductive Reasoning: GENERAL TO SPECIFIC a. Adds NO NEW knowledge, but makes relationships more APPARENT b. Helps determine the type of EXPERIMENT or OBSERVATION necessary to test a hypothesis c. Example: General Rule: All birds have wings Specific Example: Robins are birds Deduction: All robins have wings. 3. Theories: Integrated explanations of NUMEROUS HYPOTHESES *There is no ABSOLUTE TRUTH in science, only varying degrees of UNCERTAINTY!

Deductive Reasoning v. Inductive Reasoning

Super Topic 4: Risk & Risk Management Risk: PROBABILITY OF HARM Risk Assessment: using STATISTICAL METHODS to quantify the risk involved in a particular action so they can be COMPARED & CONTRASTED w/other risks. Risk Management: Determines whether a particular risk should be REDUCED or ELIMINATED, and if so, what should be done. – Considers the risk in terms of relevant POLITICAL, SOCIAL, & ECONOMIC considerations

Super Topic 4: Risk Management (Cont.) Varying Views: A.If we have control, it’s no big deal even though the risk is high (ie, a diet) B.If we don’t have control, it’s a huge deal (pesticide residue) even though the risk is low (ie, DDT is a cheap pesticide)

Super Topic 4: Risk Assessment (cont.) Four Steps of Risk Assessment: 1.HAZARD IDENTIFICATION: does exposure cause an increased likelihood of adverse health effect? 2.DOSE-RESPONSE ASSESSMENT: the relationship b/w amount of exposure and the seriousness of the health effect 3.EXPOSURE ASSESSMENT: how much, how often, how long is the exposure? 4.RISK CHARACTERIZATION: what is the probability of an individual population having an adverse health effect?

The Steps of Risk Assessment

Super Topic 5: Determining the Health Effects of Environmental Pollutants TOXICANTS: chemicals w/adverse health effects TOXICOLOGY: the study of toxicants Two types of effects of toxicants on living organisms: 1.ACUTE: Immediately or closely following exposure (ie, dizziness & and nausea) 2.CHRONIC: Long-term effects such as damage to vital organs (ie, kidney & lung damage)

Super Topic 5 (cont.) Dose and Response: 1.Lethal Dose- 50%- (LD 50 ): CAUSES DEATH IN 50% OF TEST POPULATION a.LD 50 and toxicity are INVERSELY related: As LD 50 , toxicity  (and vice versa) 2. Sub-Lethal Dose: causes harm, not death 3. Threshold: maximum dose w/no measurable effect a. Any dose less than threshold is safe 4. Effective Dose- 50% (LD 50 ): causes a specific reaction within the BULK OF THE POPULATION

Super Topic 5 (cont.)

Super Topic 6: Cancer-Causing Substances & Risk Assessment of Chemical Mixtures CARCINOGEN: cancer causing substance How to determine if chemicals are the cause – EPIDEMIOLOGICAL evidence of carcinogen exposure – ANIMAL TESTING: very controversial and not effective (animals react differently than humans) Risk Assessment of Chemical Mixtures: toxicology studies are usually performed on ONE CHEMICAL, not mixtures

Super Topic 6 (cont.) Chemicals can interact in 3 ways: 1.Additive: CHEMICALS ADD UP(1+1=2) 2.Synergistic: GREATER COMBINED EFFECT (1+1=3) 3. Antagonistic: SMALLER COMBINED EFFECT (1+1=1) *Additive approach sometimes over/under estimates the actual risk, but is still most accurate

Super Topic 7: Ecological Risk Assessment Ecological Risk Assessment: “Quantifying the PROBABLE EFFECTS of a wide range of human activities on ECOSYSTEMS.” Analysis of ERA is difficult because… 1.Many effects may be FELT ON A WIDE SCALE 2.Environmental Stressors like HUMAN INDUCED CHANGES 3.Ecological efforts are INCOMPLETELY UNDERSTOOD/HARD TO MEASURE 4.Scientific knowledge in environmental decision making is filled with UNCERTAINTY

Super Topic 7 (cont.) Example: Snake River (Idaho) – Provided irrigation for agriculture 1.Human-made changes: DAMS FOR ELECTRICITY 2.Caused: NUTRIENT ENRICHMENT,  WATER TEMPERATURES,  WATER FLOW 3.Effects: algae and aquatic blooms  FISH POPULATION  4.Ecological risk assessment helps sets priorities to meet the common goal of managing & protecting biological communities in the Snake River watershed.