COMMENT BY: HARRY A. MILMAN, Ph.D.,
Consultant in Environmental Toxicology and Science Communication
SUBJECT: Need for revision of EPA's Cancer Risk Assessment Guidelines
DATE: August 24, 1999

EPA's Cancer Risk Assessment Guidelines are long overdue for a revision and we should commend the Agency for embarking on this important undertaking. EPA is expending much effort to ensure that all relevant scientific information is considered when conducting a risk assessment and that conclusions reached are within the limits of current scientific knowledge. What may be lacking, however, is a "user friendly" document (or summary) that nonscientists (i.e., media professionals) can use to express a message to the public at large.

Today, the public obtains much of what it knows about risks from exposure to environmental chemicals from the popular press and not from federal regulatory documents or scientific publications. Average Americans learn about environmental risks from their daily newspaper or magazine, or the television or radio news broadcast. Thus, communication practitioners who are not versed in the sciences nor experienced in the "art" of cancer risk assessment are delivering scientific information to the public. With the public believing that "everything causes cancer", the question is "does the public get the right message?"

For the communications expert to do a good job, risk assessors should provide understandable scientific information, perhaps in a "user friendly" summary. The average person may not understand the difference, nor perhaps even see a difference, between the terms "possible", "probable" or "likely" carcinogen, although EPA intends that these terms reflect significant differences. What would be useful in a "user friendly" risk assessment summary is an indication, with examples, of relative risk (i.e., more risky than driving a car, of crossing the street, of flying, etc.), to which the average individual can relate. As we all know, people make their own "risk-benefit" assessments and will continue to do so. Perhaps we should give them some guideposts in terms they understand and by which they could gauge their risks.

Relative risk terminologies (i.e., "more than", "less than", "the same as") provide the lay individual a degree of relevancy. They suggest a degree of harm in familiar and understandable terms. When coupled with specific examples (such as "more risky than flying"), relative risk allows individuals to both understand and visualize risks that, in turn, may increase the likelihood that they will act appropriately.

Scientists are meticulous in their conduct of experiments, interpretation and analysis of data, and communication of their findings to other scientists. They have not, however, made much effort to express the science to the "ultimate customer" -- the public. Largely, scientists let the media both shape and deliver the message. Instead, scientists should identify the message and provide it in a clear, understandable and readily communicable format. When properly prepared, the public will hear it correctly and as intended.