Relationship Between Laboratory and Human Studies

Our plain-English summary of Relationship Between Laboratory and Human Studies, by D.B. Clayson (1977).

The study

• Author: D.B. Clayson
• Published: 1977
• Type of article: Book excerpt
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This paper by D.B. Clayson was a review, not a new study, of how well cancer findings from laboratory work (animal experiments and short-term tests) carry over to people. A table of human carcinogens appears to list asbestos with the pleura as a tumor site; the rest of that entry and a second mention of asbestos in the text are unreadable. The author described three phases in how chemicals cause cancer: metabolic activation, binding to targets such as DNA with DNA repair, and tumor development. The author wrote that DNA was most probably the critical target, on inadequate evidence. The author questioned using rodents with a 2-3 year lifespan as models for human cancers that may take 40 or more years, but wrote that practical experience suggested such models, if correctly selected and used, were valid indicators for man. The author called the reported 80-90% agreement of the Ames bacterial test with human and animal results promising. The author concluded that extrapolations to low and very low doses were presently just guesswork, and that resources did not allow experiments below the 1% tumor response level.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review and commentary on the relationship between laboratory (animal and short-term test) studies and human studies of cancer caused by chemicals; no new data were collected
• Who was studied: No study population; the paper discussed laboratory animal experiments, short-term tests and human epidemiology in general terms
• Exposure: Chemical carcinogens in general. A table of human carcinogens appears to list asbestos with the pleura as a tumor site; the rest of that entry is unreadable. Asbestos is also mentioned in one badly damaged passage of the running text, and what the author said there cannot be read reliably
• Main results:
  • The author described the critical target of chemical carcinogens as most probably DNA, while noting that the evidence was inadequate
  • The author questioned using rodents with a 2-3 year lifespan as models for human cancer that may take 40 or more years to develop, but wrote that practical experience suggested such models, if correctly selected and used, were valid indicators for man
  • The author described the reported 80-90% correlation between Ames test results and the results of human and animal studies as promising
  • The author wrote that resources were not available to run experiments below the 1% tumor response level, and that even at that level costs were prohibitive
• The authors' conclusion: The author concluded that extrapolations from laboratory results to low and very low doses were presently just guesswork, and that there was a pressing need to fuse the available data into a coherent whole

Topics

Medical terms in this study, explained in our Lexicon: Pleura.

Browse return to medical research.