LIVING WITH THE EARTH - University of South...

LIVING WITH THE EARTH

ASSESSING HUMAN RISK - Moore 1

Ob f h ChObjectives for this Chapter

• A student reading this chapter will be able to:to:– 1. Define risk and discuss the uncertainties

associated with environmental risk.associated with environmental risk.– 2. Discuss the characteristics of risk.



• A student reading this chapter will be able to:to:– 3. Define risk analysis and describe the tools

used to perform risk analysis.used to perform risk analysis. – 4. Explain the concepts of dose, extrapolation,

and acceptable daily intakes (ADI).p y ( )



• A student reading this chapter will be able to:to:– 5. List and discuss the process of risk analysis

including hazard identification, dose-responseincluding hazard identification, dose response assessment, exposure assessment, and risk characterization.

– 6. Outline and discuss the major components of risk management and risk communication.


ASSESSING HUMAN RISKASSESSING HUMAN RISK

• INTRODUCTION– Risk can be of a financial personal social– Risk can be of a financial, personal, social,

health, and environmental nature.– The word “Risk” describes a range of activitiesThe word Risk describes a range of activities,

situations and concepts, from drinking a glass of red wine daily to skydiving and extreme skiing, to chemical exposure.



• INTRODUCTION– Risk is commonly used to describe types of– Risk is commonly used to describe types of

people or situations.• Risk-taker• Risk-free

– A comparison of some of life’s risks are shown pin Figure 1.


Fig.12-1



• INTRODUCTION– People accept certain risks because they enjoy– People accept certain risks because they enjoy

the benefit they receive from the behavior or activity.y

– Some people seek out extraordinarily high levels of risk, engaging in skydiving, bungee jumping, rock and ice climbing and other extreme sports (Fig. 12-2).


F 12 2Fig. 12-2

Some risks are voluntary


E l R kEnvironmental Risk

– A central factor of environmental risk is that it is usually involuntary. y y

– People do not choose to ingest chemical pollutants such as pesticides or industrial solvents in their food and water or undergo workplace exposures to dangerous chemicals.


R k ChRisk Characteristics

• Risk can be defined as the likelihood of an unwanted occurrence coupled with anunwanted occurrence coupled with an element of uncertainty about when the risk might occurmight occur.


R k ChRisk Characteristics

• Many environmental risks have the characteristics of unknown and dread theycharacteristics of unknown and dread, they cause people anxiety and concern about the consequences of exposure to the riskconsequences of exposure to the risk.


D l f R k A lDevelopment of Risk Analysis

• Risk analysis is the process of reviewing information on a hazard to characterize thatinformation on a hazard to characterize that hazard’s impact on human health.

• Risk analysis allows public groups to make• Risk analysis allows public groups to make informed decisions and weigh the risks and benefits in their communitybenefits in their community.


Th P f R k A lThe Process of Risk Analysis

• A review of scientific studies• An understanding of the properties of a risk• An understanding of the properties of a risk, • An assessment of levels of human exposure

d dand dose• A conclusion about the likelihood, impact

and extent of a risk.


T l f R k A lTools of Risk Analysis

• Risk analysis employs several scientific disciplines in its goal to characterize a riskdisciplines in its goal to characterize a risk (Fig. 12.3).


Fig.12-3


T l f R k A lTools of Risk Analysis

• Toxicology– Toxicologists study chemicals to determine– Toxicologists study chemicals to determine

their physiological and health impacts on humans.

– Regulatory toxicology aims at guarding the public from dangerous chemical exposures.


T lToxicology

• Studies can delineate both the lower and upper limits of a chemicals potencyupper limits of a chemicals potency

• EndpointsNOEL– NOEL,

– NOAEL, LOAEL– LOAEL


DDose

• Toxicologists use different doses to elicit different animal responsesdifferent animal responses.

• Animals receiving doses above the threshold amount will begin to showthreshold amount will begin to show adverse effects and some animals will die (Fig 12 4)(Fig. 12.4).


Fig.g12-4


DDose

– LD50

– ED50ED50

– Maximum Tolerated Dose (MTD)

E S dExposure Studies

– Acute, two weeks– Subchronic, 5-90 daysSubchronic, 5 90 days– Long term or Chronic, up to two years

E lExtrapolation

In risk analysis, the term extrapolation refers to the use of animal data to predictrefers to the use of animal data to predict human response to chemical exposure.

E lExtrapolation

The results from high-dose, short duration studies are used to extrapolate humanstudies are used to extrapolate human response to the longer term, lower level exposures we generally receiveexposures we generally receive.

A bl D l I kAcceptable Daily Intakes

The purpose of toxicology studies is often to establish an acceptable level of exposureto establish an acceptable level of exposure or dose of a substance that is considered “safe”safe . This level, which poses little risk, is termed the acceptable daily intake (ADI)the acceptable daily intake (ADI).

E d lEpidemiology

Epidemiology is the study of the distribution and determinants of diseasedistribution and determinants of disease frequency in the human population.

E d lEpidemiology

Study Types– Cross-sectional– Cross-sectional– Cohort

Case Control– Case Control

Cl l T lClinical Trials

In clinical drug trials, individuals volunteer to be exposed to a substance or to ingest ato be exposed to a substance or to ingest a drug, and are assessed for their health responseresponse.

Th P f R k A lThe Process of Risk Analysis

The process of risk analysis has four steps (Fig 12-5):(Fig. 12 5):– hazard identification;

dose response evaluation;– dose-response evaluation;– exposure assessment; and

risk characterization– risk characterization.

F 12 5Fig. 12-5

H d Id fHazard Identification

The initial step in risk analysis, hazard identification involves identifyingidentification, involves identifying chemicals that present a risk to human healthhealth. This step entails performing a qualitative assessment of a chemical’s potential forassessment of a chemical s potential for negative health impacts on humans.

D R ADose-Response Assessment

The next step, dose-response evaluation, provides a quantitative view of the riskprovides a quantitative view of the risk. This step also involves a review of scientific studies and datastudies and data. In this case, the magnitude of response is

l t d ith th d (Fi 12 6)correlated with the dose (Fig, 12-6).

Fig.12-6

E AExposure Assessment

The purpose of the exposure assessment is to measure or estimate a person’s level ofto measure or estimate a person s level of exposure.Exposure is different from dose in thatExposure is different from dose in that exposure refers to the amount of a substance in the environment while dose is the levelin the environment, while dose is the level of a substance actually taken in by an organismorganism.

E AExposure Assessment

Dose can be influenced by many factors, such as how the substance enters the bodysuch as how the substance enters the body, whether absorbed through the skin, ingested with food or inhaled (Fig 12-7)with food, or inhaled (Fig 12 7).

g.12-7

R k ChRisk Characterization

Risk characterization provides a picture of the risk that addresses its severity likelihood andrisk that addresses its severity, likelihood, and consequences.The risk characterization includes an estimateThe risk characterization includes an estimate of the negative effects to exposed individuals, such as the number of cases of cancer orsuch as the number of cases of cancer or deaths per 100,000 people (Fig. 12-8).

F 12 8Fig. 12-8

L f R k A lLimitations of Risk Analysis

Limitations of risk analysis include uncertainty variability and effect ofuncertainty, variability, and effect of multiple exposures.Despite these limitations risk assessment isDespite these limitations, risk assessment is still a valuable tool for exploring and understanding the risks of the modernunderstanding the risks of the modern world.

R k MRisk Management

Risk management involves merging the results of risk analysis with various socialresults of risk analysis with various social factors, such as socioeconomic conditions, political pressures and economic concernspolitical pressures, and economic concerns (Fig. 12-9).

F 12 9Fig. 12-9


Three avenues of risk management are:– educational;– educational;– economic; and

regulatory– regulatory


Risk management generally involves comparing the risk to some other factorcomparing the risk to some other factor such as the cost, or reducing the risk or the benefit gained from the risk (Fig 12-10)benefit gained from the risk (Fig. 12 10).

Fig.Fig. 2-10


The “best” course of action is not always the one that reduces the most risk butthe one that reduces the most risk, but rather, is the most economically feasible option reducing the greatest amount of riskoption, reducing the greatest amount of risk per dollar spent.

R k CRisk Communication

The goal of risk communication is to effectively relay risk information developedeffectively relay risk information developed through risk analysis to various interested groupsgroups.


Methods of risk communication include public hearings emergency hotlinespublic hearings, emergency hotlines, information pamphlets.


Risk communication can be challenging, as it requires addressing people’s different riskit requires addressing people s different risk perceptions, biases, scientific knowledge, educational backgrounds even race andeducational backgrounds, even race and gender.


Translating technical terminology into comprehensible terminology can increasecomprehensible terminology can increase risk communication (Fig. 12-11).

F 12 11Fig. 12-11

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