Visualizing Environmental Science

Summary 93

Summary

1

A Perspective on Risks 74

1. A risk is the probability of harm (such as injury, disease,
   death, or environmental damage) occurring under certain
   circumstances. Risk assessment is the quantitative and
   qualitative characterization of risks that allows us to compare,
   contrast, and manage them.


2. Risk assessment characterizes the dose–response relationship
   between exposures to hazards and the effects of those
   exposures. These characterizations can be used to help inform
   decisions about how best to avoid, reduce, or eliminate risks.

✓✓THE PLANNER

2. While most strains of coliform bacteria do not cause
   disease, the fecal coliform test is a reliable way to indicate
   the likely presence of pathogens, or disease-causing
   agents, in water.


3. Over 25 percent of disease and injury worldwide is related to
   human-caused environmental changes. The environmental
   component of human health is sometimes direct, as when
   people drink unsanitary water and contract a waterborne
   disease. The health effects of other human activities are
   complex and indirect, as when climate change allows
   disease-causing agents to prosper.

3

Movement and Fate of Toxicants 81

1. Some toxicants exhibit persistence—they are extremely
   stable in the environment and may take many years to
   break down into less toxic forms. Bioaccumulation is
   the buildup of a persistent toxicant in an organism’s
   body. Biological magnification is the increase in toxicant
   concentration as a toxicant passes through successive
   levels of the food chain.


2. Persistent toxicants do not stay where they are applied but
   tend to move through the soil, water, and air, sometimes
   long distances. For example, pesticides applied to
   agricultural lands may wash into rivers and streams, harming
   fishes.


3. The Stockholm Convention on Persistent Organic Pollutants
   requires countries to eliminate the production and use of
   the 12 worst persistent organic pollutants (POPs). POPs
   are a group of persistent toxicants that bioaccumulate
   in organisms and travel thousands of kilometers through
   air and water, contaminating sites far removed from their
   source.

Bay Ismoyo/AFP/Getty Images, Inc.

2

Environmental Health Hazards 77

1. Toxicology is the study of toxicants, chemicals that have
   adverse effects on health. Epidemiology is the study of the
   effects of chemical, biological, and physical agents on the
   health of human populations.

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Klaus Nigge/NG Image Collection