Animal carcinogen tests often fail to predict human cancer risk

Evidence

The Environmental Protection Agency, it was true, had listed TCE as a “probable” carcinogen. But it had done so on the basis of animal tests—lab experiments in which mice, rats, and hamsters were fed enormous quantities of TCE over long periods. In one experiment, white mice had developed cancers of the lymph system, which manufactures white blood cells. But that particular strain of laboratory mouse, Jandl pointed out, was known to have a high incidence of “spontaneous” lymphosarcoma, and even the authors of the study had discounted the results. Furthermore, both Harvard doctors told Cheeseman they had little faith in extrapolating the results of animal studies to human beings. The life spans of animals, their chromosomal structures, and their metabolism were just too different. — , Harr Jonathan - A Civil Action, 647

Categorization

• XREF: Connects to standing reading on regulatory science and untested industrial chemicals — the mechanism by which a ‘probable carcinogen’ listing rests on discounted rodent data. — connects to: The motivating example: a statute enacted several decades ago bans introduction of any color additive in food if that additive ‘causes cancer’ in human beings or animals; new technologies able to detect low-level carcinogens have shown that many potential additives cause cancer even though the statistical risk is often tiny.
• QUESTION: How much of EPA’s probable-carcinogen list is built on single strained animal studies later disavowed by their own authors?

Broader Connections

• The motivating example a statute enacted several decades ago bans introduction of any color additive in food if that additive ‘causes cancer’ in human beings or animals; new technologies able to… #qualifies (0.85)