TO: Toxicology Newsgroup
FROM : Chris Schonwalder, Ph.D. (NIEHS)
SUBJECT: Report from the SOT Meeting in Anaheim
DATE: March 20, 1996
There were a number of interesting and important sessions: Some brief
highlights are below.
Epidemiology for Toxicologists: This was a continuing education course
held on Sunday. David Lilienfeld was the main presenter. The theme was
that, whereas toxicology is a prospective science which uses experimental
design and controlled exposures, very little can be actively controlled
even in prospective epidemiologic studies. Retrospectively, nothing can
be controlled. Problems, techniques and parameters used in environmental
epidemiology were described. The discussions at the end of the program
might have been the best part.
I pointed out the need for toxicologists to appreciate the problems of
environmental epidemiology in both exposure assessment and the power to
find an affect/association. American society is questioning the value of
biologic models for risk assessment. Every time we find a metabolic
differences between rodents and humans we raise the issue of relevance.
We need to instill confidence in our ability to relate our experiments to
the health consequences of human exposures. A big part of this is having
better human epidemiology. But without the biologic tools needed to
better define cause/effect, epidemiology is a poor way to learn of human
hazards. The fields of toxicology and epidemiology need to work together
to develop and use various biomarkers in human investigations. This point
was met with universal agreement from the presenters and the organizers of
Risk Communications in Toxicology: This session was presented by Peter
Sandman, who holds a Ph.D. in communications, and is well known for his
Risk = Hazard X Outrage formula. He says that most people are apathetic
to most things, but when they become upset, it is due to outrage which has
little to do with scientific fact. His theme is how to deal with the
outrage, which must be done first, and then get to the communication of
the factual hazard message. Often it is better to accept responsibility
no matter where the fault might lie, to avoid minimizing the concern, even
if the hazard is small, and to give away the credit for doing the right
thing. He is a very entertaining and effective speaker and is doing very
well as a consultant.
New Developments and Applications of Diverse Experimental Models Selected
for Specific Toxicologic Research Needs: A series of papers were
presented on how the proper choice of animal models will affect the
outcomes of toxicologic inquires. Toxicokinetic and mechanistic
considerations were the theme of these presentations. Primates, swine,
wildlife and transgenic rodents were all presented. Ray Tennants work on
transgenic rodents was well received.
Use of the Benchmark Dose vs. The Reference Dose in Risk Assessment: This
was a lively session in which a wide spectrum of opinions for and against
the use of the benchmark dose was aired. The benchmark dose is just
curve-fitting and has all the disadvantages of the mathematical models
used in cancer risk assessment was one side of the issue. The procedure
uses all available dose/ response data and does not require estimates of
NOELs or the use of default assumptions was on the other side. To me,
neither procedure removes the need for scientific understanding and
judgment and, this being the case, the arguments are constructive.
Research to understand mechanisms/modes of action will help in application
of either method.
Molecular Biomarkers in Environmental Toxicology: John Groopman chaired a
session of investigators who are working with biomarkers. It was the
regular group of investigators (Himself plus George Baily, G. Wogan, and
Martyn Smith) who presented their outstanding work and perspectives. This
area needs a push to help in human health risk assessment.
Risk Assessment and Risk Management of Workers Exposed to Pesticides:
This was an interesting session relating problems of risk assessment in
field workers to the wide variety of exposure estimates and measurement
procedures. The bottom line is that careful analysis of internal doses
shows wide differences in absorbed dose, which is greatly affected by
worker habits, protective barriers, and methods used to sample. Most
errors are large and in the direction of overestimates of exposures.
Trichloroethylene: Do the Animal Data Predict Human Cancer Risk?: This
was a short session demonstrating many of the quandaries in the field of
toxicology. Mechanisms at high dose vs. low dose, extrapolation,
classification of rodent carcinogens, effects on manufacturers of products
(Gillette had to take TCE out of White Out although the exposures to the
normal office user was extremely low), etc. all came up.
I am looking forward to reading others interpretation of these and other
issues from the SOT meeting. A good idea to have this. But how many
actively use this group? Is there any way to know?