Part I
Introductory Comments
It is better to risk saving a guilty person than to condemn an innocent one.
Voltaire (Francois Marie Arouet) (1694â1778)
Zadig [1747], Chapter 6
1
About the Book
1.1 Introduction
The rapid growth and expansion of the chemical and energy industry has been accompanied by not only a spontaneous rise in chemical emissions to the environment but also human, material, and property losses because of fires, explosions, hazardous and toxic spills, equipment failures, other accidents, and business interruptions. Concern over the potential consequences of these massive emissions and catastrophic accidents, particularly at chemical, petrochemical, and utility plants, has sparked interest at both the industrial and regulatory levels in obtaining a better understanding of the main subject of this book: Environmental Health and Hazard Risk Assessment: Principles and Calculations. The writing of this âriskâ book was undertaken, in part, as a result of this growing concern.
Risk of all types (health risk, hazard risk, individual risk, societal risk, etc.) has surged to the forefront of numerous engineering and science areas of interest. Why? A good question. Some of the more obvious reasons include (not in the order of importance) the following:
1. Increased environmental health and safety legislation
2. The accompanying massive regulations
3. Regulatory fines
4. Liability concerns
5. Environmental activists and their organizations
6. Public concerns
7. Skyrocketing health care costs
8. Skyrocketing workersâ compensation costs
9. Codes of ethics
These factors, individually or in toto, have created a need for engineers and scientists to develop a proficiency in risk and risk-related topics. In turn, this need gave rise to the driving force that led to the writing of this book.
Members of society are confronted with risks on a daily basis. Here is a sampling of some activities for which risk can play a role:
1. Electrocution when turning on the TV
2. Using soap with chemical additives
3. Tripping down stairs
4. Drinking Starbucks coffee
5. Driving to work
6. Eating a hot dog for lunch
7. Being struck by an automobile while returning from lunch
Risks abound. They are all around us and society has little to no control over many of them. Perhaps a careful analysis of risks is on order.
Health problems and accidents can also occur in many ways other than from routine, daily, ânormalâ activities. There may be a chemical spill, a round-the-clock emission from a power plant, an explosion, or a runaway reaction in a nuclear plant. There are also potential risks and accidents in the transport of people and materials: trucks overturning, trains derailing, ships capsizing, etc. There are âacts of Godâ such as earthquakes, tsunamis, and tropical storms. It is painfully clear that health and hazard problems are a fact of life. The one common thread through all of these situations is that these problems are rarely understood and, unfortunately, they are frequently mismanaged.
The job of the engineer and scientist is to measure or calculate the magnitude of risk and often compare the magnitude of one risk to other risks that are similar in nature. Perhaps more difficult is the task of comparing the risk of one event with risks arising from events of a totally different nature.
Topics addressed in this chapter include:
Why use risk-based decision making?
Definitions
Risk terms
Financial risk
1.2 Why Use Risk-Based Decision Making?
The use of a risk-based decision-making process allows for efficient allocation of limited resources such as time, money, regulatory oversight, and qualified professionals. Advantages of using this process include the following:
1. Decisions are based on reducing the risk of adverse human or environmental impacts.
2. Data collection activities are focused on collecting only that information that is necessary to make risk-related decisions.
3. Limited resources are focused on those sites or scenarios that pose the greatest risk to human health and the environment.
4. Compliance or risk mitigation effectiveness can be evaluated relative to site-specific standards or goals.
5. More cost-effective risk mitigation may be achieved, oftentimes more rapidly, than is normally possible.
By using risk-based decision making, decisions are made in a consistent manner. Protection of both human health and the environment is accounted for.
A variety of U.S. Environmental Protection Agency (EPA) programs involved in the protection of groundwater and cleanup of environmental contamination utilize the risk-based decision-making approach. Under the EPAâs regulations dealing with the cleanup of underground storage tank (UST) sites, regulators are expected to establish goals for cleanup of UST releases based on consideration of factors that could influence human and environmental exposure to contamination. Where UST releases affect the groundwater being used as public or private drinking water sources, EPA generally recommends that cleanup goals be based on health-based drinking water standards. Even in such cases, however, risk-based decision making can be employed to focus on corrective action.
In the Superfund program (see Chapter 5), risk-based decision making plays an integral role in determining whether a hazardous waste site belongs on the National Priorities List. Once a site is listed, qualitative and quantitative risk assessments are used as the basis for establishing the need for action and for identifying remedial alternatives. To simplify and accelerate baseline risk assessments at Superfund sites, EPA has developed generic soil screening guidance that can be used to help distinguish between contamination levels that generally present no health concerns and those that generally require further evaluation. The Resource Conservation and Recovery Act (RCRA) Corrective Action Program also uses risk-based decision making to set priorities for cleanup so that high-risk sites receive attention as quickly as possible to assist in the determination of cleanup standards and to prescribe management requirements for remediation of wastes.
It should be noted that disasters and accidents in the past have become the driving force for innovation from a risk perspective. The trial-and-error process associated with the development of the chemical, petrochemical, space, nuclear, etc., industries have unfortunately resulted in the loss of an untold number of lives. Failure has never been desirable. But failures, often appalling and inevitable, almost always have assisted engineers and scientists in preventing future, potentially more catastrophic failures. In effect, much of todayâs technological development can be attributed to failures that society often chooses to forget. Hopefully, the recent BP offshore oil rig disaster, to be discussed in Chapters 3, Chapter 21, and Case Study 4, will lead to additional and more meaningful technological advancements in deep water offshore oil drilling.
1.3 Book Contents
As is usually the case in preparing a manuscript on risk, the decisions of what to include and what to omit have been difficult. However, every attempt has been made to offer engineering and science (course) material to readers at a level that will enable them to better cope with some of the complex problems encountered in this field.
This book is divided into four parts: Introductory Comments, Health Risk Assessment, Hazard Risk Assessment, and Case Studies. Part I, an introduction to health risk and hazard risk, presents regulatory considerations, emergency planning, and emergency response. This part basically serves as an overview to the more technical topics covered in the remainder of the book. Part II treats the broad subject of health risk assessment (HRA), including such topics as health problem identification, toxicology, exposure assessment, and health risk characterization. The chapters in Part III provide material related to hazard risk assessment (HZRA), including topics such as probability calculations, consequence estimation, and hazard risk characterization. Part IV examines risk assessment from a case study perspective; chapters in this final part include material on four subject areas that includes applications and calculations for risk assessments of real systems.
Part I of this book serves as an introduction to the general subject of Health risk and hazard risk. There are six chapters in Part I. An introduction to the subject is presented in Chapter 1, along with definitions, risk terms, and financial risk topics. Chapters 2 and 3 examine health problems and hazard problems, respectively, while Chapter 4 discusses the differences between the two. Chapter 5 is concerned with legislation. The major applicable pieces of legislationâthe Clean Air Act, the Clean Water Act, the Resource Conservation and Recovery Act (RCRA), the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and the Superfund Amendments and Reauthorization Act (SARA)âare discussed. Increased public awareness is the major thrust of the Title III legislation, which is the heart of SARA. SARA Title III established requirements for emergency planning and âcommunity right to knowâ for federal, state, and local governments...