Risk and Human Health

Environmental Risk Analysis Comparing the risk of a situation to its benefits Allows people to evaluate and deal with consequences based on their probability of occuring

Four classes of risk 1. High risk – obviously dangerous things to do smoking, drinking and driving 2. Low risk – infrequent events that may have large consequences Earthquake on the East coast of the US 3. Very low risk – events that have never occurred in recorded history Major meteor striking North America 4. Mixed risk – outcomes that increase in frequency against a background of occurrences Additional cancer cases beyond what is normal

Types of preferences to risk 1. Revealed – observations on the risks people actually take 2. Expressed – risk people say they are willing to take 3. Natural Standards – levels or risk humans have lived with in the past

Comparing risk Risk estimation – a scientific question How much risk is there? Risk acceptability – a political question How much risk is acceptable for people to take?

External Factors Regarding Risk Public concern Economic interest Legislative actions

Risk Analysis Risk Assessment Objective assessment of risk Identify hazards Dose-response assessment Exposure assessment Risk characterization Risk Management Determining what to do about risk Risk identification Use of mitigating measures to reduce risk

Health Effects Acute = sudden severe exposure and rapid absorption of the substance Normally from a single large dose Health effects are usually reversible Chronic = prolonged or repeated exposures over many days, months, or years Symptoms not immediately apparent Health effects not reversible

Dose-Response Relationships Describe the change in effect on an organism or population caused by differing levels of exposure or substance Graph relates amount of drug/toxin on x- axis and response on y-axis Threshold dose – dose where a response is first observed

LD 50 – Lethal dose 50% Dose which kills half of the population within 14 days

EC 50 – Effect concentration Concentration where 50% of the population observes an effect

Worksheet Instead of more notes you will complete a worksheet on this material and review previous notes as reference

Economic Impacts Costs: the expenses, in energy, time, money, etc. related to doing a particular activity or obtaining a product Can be one time or ongoing Benefits: the value one obtains from an activity or product Usually received over time

Cost-Benefit Analysis A technique for deciding whether to make a change If Benefits > Costs then go ahead with endeavor If Benefits < Costs then do NOT go ahead with endeavor

Types of cost-benefit analyses Simple: only looks at financial aspects Complex: looks at environmental, social, and other aspects as well as financial High subjective

Situations where cost- benefit analysis applies 1. Judge whether public service provided by the private sector are adequate 2. Used when judging and assessing inefficiencies (market failures) in the private sector and their impacts on health, safety, and environment 3. Helps in determining how to meet social needs in a cost-effective manner in areas the government can address

Cost-benefit analyses requires 1. Gathering all information and data about a public issue, including history and background 2. Defining the possible solutions to solving the issue 3. Brainstorming the possible environmental and societal consequences of the alternatives 4. Quantifying the benefits and the costs 5. Making decisions and balancing concerns

Framework of a cost-benefit analysis StepDescription Cost-benefitDetermine an action and levels of action that achieve the greatest net economic benefit Exploring options and determining incremental levels of remediation provide the most benefit for the least cost Cost- effectiveness Implementing a specific objective at the least cost Emphasis is on achieving the objective Flexible regulatory guidelines are adapted to find the lowest cost to solve a problem

Framework of a cost-benefit analysis StepDescription Health or Environmental protection standards Reducing risk to the public whatever the cost Risk-benefitBalancing health or environmental protection with the costs of providing the protection TechnologyTo achieve the results that are predictable and certain

Homework: Define and describe the following in your notes External Costs Ecotaxes (green taxes) Cap and Trade