Session 1

 

Chapters 1 & 2

Preview, Science & Methods

 

 

 

 

Flash Cards Chapter One; Flash Cards Chapter Two:

Slides Chapter One: Slides Chapter Two:

Key Concepts:

  1. Environmental health science distinguishes among chemical, physical, biological, and social hazards to human health.
  2. Modern Western-style development creates many products and wastes, some of which create hazards to human health.
  3. Modern Western-style development changes the environment in ways that are neither sustainable nor equitable at a global scale.
  4. In terms of their behavior in the environment, organic chemicals have characteristic tendencies.
  5. Although they make up only a small proportion of the atmosphere, certain gases in the Earth’s atmosphere have important functions.
  6. Water circulates through the environment, as shown in Figure 2.3 in the textbook. Important parts of the hydrologic cycle take place underground and may be unfamiliar to some readers.
  7. Environmental chemicals can enter the body, where they may be transformed, transported, and ultimately removed from the body.
  8. The quantitative relationship between the dose of a toxicant and its toxic effect is usually presented as a dose–response curve.
  9. The chronic rodent bioassay is the cornerstone of toxicity testing in animals.
  10. Given that “the dose makes the poison,” it is important to measure or estimate exposure as accurately as possible. Modern science frames the assessment of exposure in terms of an exposure pathway.
  11. Ideally, exposure is quantified inside the body. However, often this is not practical, and a measurement made in the environment is used as proxy.
  12. As a practical matter, certain environmental media are most associated with each of the three major routes of exposure.
  13. Modern science uses various techniques to measure or estimate exposure all along the exposure pathway.
  14. he units typically used to quantify absorbed dose are milligrams of toxicant per kilogram of body weight per day, or mg/(kg 3 day).
  15. Epidemiologists use three distinct measures—incidence, prevalence, and mortality — to quantify a given disease in a population.
  16. Surveillance epidemiologists typically use one of two measures to compare rates of death and disease in different populations: the standardized rate ratio or the standardized incidence (or mortality) ratio.
  17. Several distinct study designs are used in environmental epidemiology, depending on the investigator’s purpose and the availability of data.
  18. Not every statistical association represents a causal association.
  19. Community participation in health research is often valuable.
  20. Risk assessment is an applied science used to evaluate the public health risk of environmental hazards using information on exposure and toxicity.
  21. The conceptual divide between non-cancer and cancer health effects that appeared in toxicology is carried through in the risk assessment of chemicals. Therefore, the four major steps in risk assessment are parallel, but not the same, in risk assessment for non-cancer and cancer effects of chemicals.
  22. When the risk assessment approach is applied to a site, the same four steps are followed, but they play out differently in this context. This is because most sites are contaminated by multiple chemicals and because each contaminated site offers a different set of opportunities for exposure (see Table 2.6).
  23. In environmental health, risk management consists of actions taken to control or reduce environmental health risks.
  24. Many risk management actions are not as straightforward as setting a drinking water standard.
  25. The general public’s perception of risk has been called “hazard plus outrage.”
  26. Communication between epidemiologists and research subjects has expanded well beyond informed consent.
  27. The consensus conference, though rarely used in the United States, is a sophisticated form of risk communication.
  28. The precautionary principle is an alternative to the mindset of the risk assessment – risk management paradigm.
  29. Implementing a precautionary approach in the United States would represent a major shift from the risk assessment–risk management paradigm.
  30. Using a structured process, it is possible to tap the collective knowledge and judgment of the lay public in the development of scientific knowledge.
  31. Like a risk assessment, the health impact assessment is a structured process to evaluate public health impacts; unlike risk assessment, it looks forward rather than backward in time.

Links

Learning Objectives:

  • After studying this chapter, the reader will be able to:

  • Define or explain the key terms introduced throughout the chapter.

  • Describe the scope of environmental health as a field of research and practice.

  • Articulate key aspects of Western-style development and its impacts.

  • Define or explain the key terms introduced throughout the chapter.

  • Define and distinguish among the key scientific and methodological domains of environmental health and explain how they relate to one another.

  • Explain how natural environmental processes and the characteristics of individual chemicals together affect the fate and transport of chemicals in the environment.

  • Describe routes of exposure and excretion, distinguish between exposure and dose and among different measures of dose, and interpret the key features of a dose–response curve based on a rodent bioassay.

  • Present a conceptual model of exposure, identifying key events and processes as well as estimates of a toxicant or its effects; distinguish between routes and pathways of exposure; and explain the standard units of absorbed dose.

  • Explain the distinction between descriptive and analytic epidemiologic study designs, compare and contrast the key measures used in surveillance, and discuss criteria for concluding that a statistical association represents a causal connection.

  • Describe the core principles of community-based participatory research.

  • Describe the major steps in a risk assessment for the noncancer and carcinogenic effects of a chemical, explaining the outcome or product of each step, and contrast procedures for the risk assessment of a chemical with those for the risk assessment of a site.

  • Define risk management, distinguishing it from risk assessment, and give examples of risk-management decisions or strategies.

  • Summarize the range of activities that fall under the rubric of risk communication.

  • Articulate the key elements of the precautionary principle as it is invoked in environmental health and describe some practical policy tools that reflect a precautionary mindset.

Homework:

Answer all of the following study questions and email the attached questions and answers in Word of pdf format to the instructor by Canvas email no later than 5 pm on Sunday the last day of Session 1. In the beginning of your emial message identify the class session for the homework being submitted.

Study Questions

1. Contrast the typical profiles of higher- and lower-molecular-weight chemicals as to their physical–chemical properties and their behavior in the environment.

2. What is the term used to describe a chemical that tends to move from water into an oily medium? (You will need to do web research to answer this).

3. Describe what you would expect to be the volatility and solubility of low-molecular weight chemicals. (You will need to do web research to answer this).

4. Generally speaking would we expect low-molecular weight chemicals to be highly soluble in water, persistent in the environment or to be bioconcentrated? (You will need to do web research to answer this).

5. Generally speaking where in the environment would you be most likely to encounter high-molecular weight chemical accumulations: body fat? soils and sediments? in the atmosphere? (You will need to do web research to answer this).

6. Assess the advantages and disadvantages of epidemiology and rodent bioassays as sources of information about the human health effects of environmental chemicals.

7. Suppose that a surveillance biomonitoring program has measured concentrations of polybrominated diphenyl ethers (PBDEs) in women’s breast milk, with the goal of describing exposure at the population level. Much is still unknown about the toxicity of these common flame-retardant chemicals. Would you recommend that the results of the biomonitoring be reported back to the study participants? Why or why not?

8. As you begin your study of environmental health, note any environmental health problems that have been important in your own life or in areas where you have lived.

9. Explain why risk assessors use a reference dose to quantify noncarcinogenic toxicity, but use a cancer slope factor to quantify carcinogenic toxicity.

10. Identify two environmental health topics that you think are ripe for a Danish-style consensus conference, and formulate the specific question to be addressed.