• Table A.1: Concentration Comparisons Organized by Unit Categories
• Table A.2: Miscellaneous Concentration Comparisons
• Figure A.1: Air Emissions from Chemical Production: Tons per Year Projected through 1988 for the Dow Chemical Company, Midland Division

WARNING NOTES ON TABLES:

1. The data in the tables are designed to stress how small small really is. By minimizing magnitude, the comparisons tend to minimize risk.

2. When the data in the tables are used by those with an obvious interest in minimizing risk, they often lack credibility. They are also likely to provoke the same sort of backlash provoked by self-serving risk comparisons.

3. The data often lack relevance and meaning unless coupled with data on the toxic potency of a particular chemical.

4. Efforts to minimize small quantities through the comparisons given in the tables may backfire by making the quantity easier to visualize. While an image such as "a drop of vermouth in 500 barrels of gin" may be intended to convey smallness, for some in the audience it serves as an easily visualized and memorable metaphor.

Parts per million:

• One automobile in bumper-to-bumper traffic from Cleveland to San Francisco
• One drop of gasoline in a full-size car’s tankful of gas
• One facial tissue in a stack taller than the Empire State Building
• One pancake in a stack four miles high

Parts per billion:

• One silver dollar in a roll of silver dollars stretching from Detroit to Salt Lake City
• One kernel of corn in enough corn to fill a 45-foot silo, 16 feet in diameter
• One sheet in a roll of toilet paper stretching from New York to London

Parts per trillion:

• One square foot of floor tile on a kitchen floor the size of Indiana
• One drop of detergent in enough dish-water to fill a train of railroad tank cars ten miles long
• One mile on a two-month journey at the speed of light

Parts per quadrillion:

• One postage stamp on a letter the size of California and Oregon combined
• The palm of one’s hand resting on a table the size of the United States
• One human hair out of all the hair on all the heads of all the people in the world
• One mile on a journey of 170 light years

Source: Adapted from data supplied by Jim Callaghan, Hill and Knowlton, Inc., as reproduced in P. Sandman, D. Sachsman, and M. Greenberg, 1987, Risk Communication for Environmental News Sources. Industry/University Cooperative Center for Research in Hazardous and Toxic Substances: New Brunswick, New Jersey.

Figure A.1: Air Emissions From Chemical Production:
Tons per Year Projected through 1988 for
the Dow Chemical Company, Midland Division

Image not available

Source: Adapted from Midland Daily News, June 5, 1987.

Introduction and Index       I . Effectively Communicating Risk Information       II. Guidelines for Presenting and Explaining Risk-Related Numbers and Statistics       III. Guidelines for Providing and Explaining Risk Comparisons       IV. Concrete Examples of Risk Comparisons       V. Anticipating Objections to Explanations of Chemical Risks       Conclusion       Acknowledgements       Appendix A: Concentration and Quantity Comparisons       Appendix B: Risk Comparison Tables And Figures       Appendix C: Risk Perception Factors       Selected Bibiliography on Risk Communication

      

Peter M. Sandman 59 Ridgeview Rd. Princeton NJ 08540-7601	Phone: 1-609-683-4073 Fax: 1-609-683-0566 Email: peter@psandman.com
Website design and management provided by SnowTao Editing Services.