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ASSESSING HUMAN RISK - Moore

LIVING WITH THE EARTH

ASSESSING HUMAN RISK - Moore

Objectives for this Chapter

A student reading this chapter will be able to:
1. Define risk and discuss the uncertainties associated with environmental risk.
2. Discuss the characteristics of risk.

ASSESSING HUMAN RISK - Moore

Objectives for this Chapter

A student reading this chapter will be able to:
3. Define risk analysis and describe the tools used to perform risk analysis.
4. Explain the concepts of dose, extrapolation, and acceptable daily intakes (ADI).

ASSESSING HUMAN RISK - Moore

Objectives for this Chapter

A student reading this chapter will be able to:
5. List and discuss the process of risk analysis including 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 RISK - Moore

ASSESSING HUMAN RISK

INTRODUCTION
Risk can be of a financial, personal, social, health, and environmental nature.
The 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.

ASSESSING HUMAN RISK - Moore

ASSESSING HUMAN RISK

INTRODUCTION
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 in Figure 1.

ASSESSING HUMAN RISK - Moore

Fig.
12-1

ASSESSING HUMAN RISK - Moore

ASSESSING HUMAN RISK

INTRODUCTION
People accept certain risks because they enjoy the benefit they receive from the behavior or activity.
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).

ASSESSING HUMAN RISK - Moore

Fig. 12-2

Some risks are voluntary

ASSESSING HUMAN RISK - Moore

Environmental Risk

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

ASSESSING HUMAN RISK - Moore

Risk Characteristics

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

ASSESSING HUMAN RISK - Moore

Risk Characteristics

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

ASSESSING HUMAN RISK - Moore

Development of Risk Analysis

Risk analysis is the process of reviewing information on a hazard to characterize that hazard’s impact on human health.
Risk analysis allows public groups to make informed decisions and weigh the risks and benefits in their community.

ASSESSING HUMAN RISK - Moore

The Process of Risk Analysis

A review of scientific studies
An understanding of the properties of a risk,
An assessment of levels of human exposure and dose
A conclusion about the likelihood, impact and extent of a risk.

ASSESSING HUMAN RISK - Moore

Tools of Risk Analysis

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

ASSESSING HUMAN RISK - Moore

Fig.
12-3

ASSESSING HUMAN RISK - Moore

Tools of Risk Analysis

Toxicology
Toxicologists study chemicals to determine their physiological and health impacts on humans.
Regulatory toxicology aims at guarding the public from dangerous chemical exposures.

ASSESSING HUMAN RISK - Moore

Toxicology

Studies can delineate both the lower and upper limits of a chemicals potency
Endpoints
NOEL,
NOAEL,
LOAEL

ASSESSING HUMAN RISK - Moore

Dose

Toxicologists use different doses to elicit different animal responses.
Animals receiving doses above the threshold amount will begin to show adverse effects and some animals will die (Fig. 12.4).

ASSESSING HUMAN RISK - Moore

Fig.
12-4

ASSESSING HUMAN RISK - Moore

Dose

LD50
ED50
Maximum Tolerated Dose (MTD)

ASSESSING HUMAN RISK - Moore

Exposure Studies

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

ASSESSING HUMAN RISK - Moore

Extrapolation

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

ASSESSING HUMAN RISK - Moore

Extrapolation

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

ASSESSING HUMAN RISK - Moore

Acceptable Daily Intakes

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

ASSESSING HUMAN RISK - Moore

Epidemiology

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

ASSESSING HUMAN RISK - Moore

Epidemiology

Study Types
Cross-sectional
Cohort
Case Control

ASSESSING HUMAN RISK - Moore

Clinical Trials

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

ASSESSING HUMAN RISK - Moore

The Process of Risk Analysis

The process of risk analysis has four steps (Fig. 12-5):
hazard identification;
dose-response evaluation;
exposure assessment; and
risk characterization.

ASSESSING HUMAN RISK - Moore

Fig. 12-5

ASSESSING HUMAN RISK - Moore

Hazard Identification

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

ASSESSING HUMAN RISK - Moore

Dose-Response Assessment

The next step, dose-response evaluation, provides a quantitative view of the risk.
This step also involves a review of scientific studies and data.
In this case, the magnitude of response is correlated with the dose (Fig, 12-6).

ASSESSING HUMAN RISK - Moore

Fig.
12-6

ASSESSING HUMAN RISK - Moore

Exposure Assessment

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

ASSESSING HUMAN RISK - Moore

Exposure Assessment

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

ASSESSING HUMAN RISK - Moore

Fig.12-7

ASSESSING HUMAN RISK - Moore

Risk Characterization

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

ASSESSING HUMAN RISK - Moore

Fig. 12-8

ASSESSING HUMAN RISK - Moore

Limitations of Risk Analysis

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

ASSESSING HUMAN RISK - Moore

Risk Management

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

ASSESSING HUMAN RISK - Moore

Fig. 12-9

ASSESSING HUMAN RISK - Moore

Risk Management

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

ASSESSING HUMAN RISK - Moore

Risk Management

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

ASSESSING HUMAN RISK - Moore

Fig.
12-10

ASSESSING HUMAN RISK - Moore

Risk Management

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

ASSESSING HUMAN RISK - Moore

Risk Communication

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

ASSESSING HUMAN RISK - Moore

Risk Communication

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

ASSESSING HUMAN RISK - Moore

Risk Communication

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

ASSESSING HUMAN RISK - Moore

Risk Communication

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

ASSESSING HUMAN RISK - Moore

Fig. 12-11

ASSESSING HUMAN RISK - Moore