November Discussion--Flaws in Risk Assessment
In the Oct. 13 editorial on p. 215 of the journal Science, Dr. P. Abelson writes
"Chemical risk assessment studies conducted with rodents have helped to
justify expenditures of more than a trillion dollars over the past 20
years. Large additional outlays are planned, although it has not been shown
that such studies have substantially benefited human health. In fact, it
has become increasingly clear that the main causes of untimely human death
are smoking and diet."
Dr. Abelson later goes on to cite data indicating that genetic drift in the
rodent strains used in carcinogenesis studies along with ad lib. feeding
contribute to irreproducible and unreliable results. He quotes studies
showing that tumor incidence in test strains has steadily increased while
the percentage of animals reaching 2 y or more in age has steadily
declined due to a variety of degenerative diseases.
For example, today the average weight of a rodent is 20-30% greater than it
was 25 y ago. About 60% of Sprague-Dawley rats survived to 2 y of age in
the '70s, while currently only 24% do so.
Question 1. Is it time for risk assessment to pack it up and move on to
Question 2. Does the fact that risk assessment can't show a "substantial
benefit to human heath" negate its value?
Question 3. Does the fact that toxicologists are currently performing
experiments on tumor-prone obese rodents with degenerative diseases make
for BETTER extrapolation to risk prediction in the modern human population?
Question 4. Have risk assessment people taken enough abuse or do they
Please direct your e-mail replies to the group at toxicol at net.bio.net.
Dr. Charles A. Miller, rellim at mailhost.tcs.tulane.edu
Dept. Environmental Health Sciences
Rm. 374, Center for Bioenvironmental Research
School of Public Health and Tropical Medicine
Tulane University Medical Center
1430 Tulane Ave. Box SL29
New Orleans, LA 70112
Ph. 504-585-6942, Fx. 504-585-6939