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HW 3 and Final Report  Position paper – due Thursday, Nov. 16th  Risk Management Report – due Tuesday, Dec.

5th at 5:00pm

 Materials posted on Canvas

 Recitation on your own on Thursday, Nov. 9

Risk Assessment and

Risk Perception

Key Concepts

 Understand the elements of risk, including various types of risks.

 Consider how risk perception influences society.

 Be familiar with the major components of risk assessment: hazard assessment, dose-response, exposure assessment and risk characterization.

Naturally occurring fibrous minerals with high tensile strength

Resistance to heat and most chemicals

The ability to be woven

 fireproofing  fire blankets  sheetrock taping  vinyl floor tiles, sheeting,

adhesives and ceiling tiles  roofing tars, felts, and shingles  acoustical ceilings  brake pads and shoes

Used for more than 2,000 years

Ancient Greeks noted “sickness of the lungs” in slaves that wove asbestos into cloth

Became popular again in the Industrial Revolution (late 1800s)

1917 – US studies show asbestos workers dying unnaturally young

1924 – first diagnosis of asbestosis

1931 – laws passed to increase ventilation (in England)

1930s – medical journals publishing articles that link asbestos to cancer

$300 million in lawsuits against employers

Asbestos companies began to cover up health effects of asbestos

Asbestos companies continued to use asbestos although other materials were available (fiberglass)

1930s-1970s – Companies ignored the danger for sake of profit – exploited workers who were unaware of the health risks

How many people died from asbestos related causes since 1979?

At Least 43,073 People Have Been Killed By Asbestos Since 1979

$300 million in lawsuits against employers

Asbestos companies began to cover up health effects of asbestos

Asbestos companies continued to use asbestos although other materials were available (fiberglass)

1930s-1970s – Companies ignored the danger for sake of profit – exploited workers who were unaware of the health risks

1970s – EPA and OSHA began to regulate asbestos

Asbestos Carbon nanotubes

 High aspect ratio nanoparticles (HARN)  UK Report (Aug. 2008) – Should HARN raise same

concerns as asbestos fibers?  Objectives of study

 Review literature on fibers and HARN  Set research strategy to determine if health concerns are real

Asbestos fiber Carbon nanotube

“Frustrated Phagocytosis”

 Is the similarity in shape between asbestos and CNTs concerning?

 What lessons learned from the asbestos crisis could be applied to the new development of CNTs?

Risk

Relative Risk: comparative risk between different levels or entities. For instance, smokers have a relative risk of 10 compared with non-smokers for developing lung cancer (10x more likely). Or the risk of a child being seriously injured by a vehicular air bag is less relative to the number of serious injuries prior to air bags.

Absolute & Relative Risk Absolute Risk: quantifiable risk without context. For instance, you have a 1/6 chance of rolling a “6” on a die.

Risk of dying in U.S.

National Geographic 2006

Expert’s definition of

risk

Public’s definition of

risk

probability x consequence

hazard + outrage

Who Defines Risk?

 Food coloring

 

 



 





 





 



Saccharin Microwave ovens

Aspirin

Anesthetics

Power Tools

Alcohol

Motor vehicles

DNA Research

Nuclear Power

Asbestos

Herbicides Pesticides

Smoking

Dynamite

Warfare

Handguns

Risk Perceptions

 Lead Unknown

Known

Dreaded Little Dread

A Small Dose of Toxicology, modified

Risk Perception

Catastrophic Potential

Voluntary/ Involuntary Familiar/

Unknown

Fair/ Unfair

Effects on Children?

Benefits? Dread

Trust

Elements of Risk Perception

Adapted from Slovic et al. (1979), Environ., 21: 14.

Differences in Risk Perception

Activity/Agent Rank by Risk Analyst

Rank by non- Risk Analyst

Motor Vehicles 1 2 Smoking 2 4 Alcohol 3 6

Handguns 4 3 Surgery 5 10 Motorcycles 6 5

X-rays 7 22 Pesticides 8 9 Electric Power 9 18

Swimming 10 19 Nuclear Power 20 1

Objectives of Risk Assessment

Identify & evaluate potential risks  Environmental contaminants, drugs,

pesticides, industrial chemicals, nanoparticles

Characterize uncertainty in data Set target levels of exposure  Food, air, soil, water, work place

Provide information to agencies  Regulatory agencies, Manufacturers,

Environmental/Consumer Agencies

A Small Dose of Toxicology, modified

Risk Assessment

Hazard Identification

Exposure Assessment

Dose-Response Assessment

Risk Characterization

Risk Management

Hazard Identification

Structure-Activity Analysis -resemblance to other chemicals -computer modeling

Short-term Screening Tests -cell, tissue, microorganism, other

Animal Bioassays

Human Epidemiological Data

Hazard Identification

Weight-of-evidence approach Identify Principle & Supportive Studies

• Will require some research • Primary literature - ICON Database • Databases - NBI knowledgebase, Nanomaterial

Registry, Hazardous Substances Data Bank • Use of surrogates (bulk materials, natural or anthropogenic ultra-fine particles, other engineered nanoparticles)

Select Toxic Endpoints

• Consider the use of the application (Scope)

Toxicity Endpoints

-Carcinogenicity -Mutations -Altered immune function -Teratogenicity -Altered reproductive function -Neurological & behavioral toxicity -Organ-specific effects -Ecological effects (wildlife, environmental persistence)

A Small Dose of Toxicology, modified

The hazard identification process requires significant professional judgment. Nearly all chemicals have uncertain and incomplete information for toxicity.

Causes of Uncertainty

Deficiencies in experiments (dosing, sample size, animal husbandry, and more) Extrapolation from animal studies to human (relevance, consistency) Endpoint selection Intra and inter subject variability Insufficient reporting

A Small Dose of Toxicology, modified

Exposure Assessment

Often, the most uncertainty in a risk assessment stems from inadequate characterization of exposure. This includes the: -Exposure routes -Duration of exposure -Amount of exposure (dose) -Exposed Population

Remember, hazard alone does not imply risk…

vs.

How do we assess exposure?

-Biomonitoring -Biomarkers -Exposure History

-Epidemiology -Environmental Sampling -Exposure Modeling

Keywords for exposure information Again, surrogates may be necessary

Exposure Model

Surface Water

Primary Exposure Mechanism

Irrigation Water

Farm Produce & Feed

Drinking Water & Cooking

Water

Secondary Sources

Exposure Medium

Microcystin Toxins

Exposure Routes

Receptors

Ingestion

Ingestion

Ingestion

Ingestion Aspiration Dermal

Complete Exposure Pathway Incomplete or Unknown Exposure Pathways

Notes:

Primary Producer

Groundwater

Human Non* Human Adult

Child

Primary Sources

•Toxigenic Cyanobacteria

Ingestion

Domestic Wells

Drinking Water

Recreational &

other waters

Inhalation Dermal

Food supplements

Drinking Water Systems

Showering

Fish & Shellfish Ingestion

Stock ponds Ingestion

Current models cannot always be applied to nanomaterials

Dose-Response • The magnitude of the toxic response is

proportional to the concentration (how much) of the chemical at the target site.

• The concentration of a chemical at the target site is proportional to the dose.

• Four important processes control the amount of a chemical that reaches the target site.

– Absorption

– Distribution

– Metabolism

– Excretion

Society of Toxicology 2008 (modified)

Mild Extreme

Many

Few

N um

be r

of In

di vi

du al

s

Response to SAME dose

Sensitive Individuals

Maximal

Effect

Resistant Individuals

Minimal Effect

Majority of Individuals

Average Effect

Exposure-Response

Society of Toxicology 2008

Uncertainty Factors

Human variability

Interspecies extrapolation

Children & sensitive populations

Subchronic to chronic extrapolation

Absence of NOAEL

Lack of critical study

Use of Uncertainty Factors

Animal Dose Response Data

NOAEL (No Observed Adverse Effect Level)

Divide by 10

(Account for inadequate animal data)

Divide by 10

(Animal to Human Extrapolation)

Divide by 10

(Human Variability or Individual Sensitivity)

Reference Dose (RfD) Or Acceptable Daily Intake (ADI) A Small Dose of Toxicology

• Assessment of exposure & exposed population • Consideration of uncertainty • Consideration of weight-of-evidence • Comparison of RfD to estimated (or measured) dose

Risk Characterization

Risk = Hazard X Exposure (+uncertainty?)

“Shu`xwee-nish mvlh Lhuk” (Good living with fish) Coloring Book

Confederated Tribes of Siletz Indians & Oregon Department of Human Services

Women of child-bearing age, especially pregnant & nursing mothers, infants & young children, and people with pre-existing liver or immunological problems should consume no more than one 6-ounce meal/month.

Healthy adults may ingest up to three 8-ounce meals per month.

Risk Characterization