related to human data are identified in Tables 3-1 through 3-5. An important concept in Chapter 4 that is not captured in the spectra of concern tables is that historical use information becomes less relevant as difference from traditional use increases. Changes in historical versus modern use may arise from new methods of preparation (e.g., plant part used or extraction process) or new patterns of use (e.g., higher intake level, route of administration, duration and frequency of consumption, indication for use).
Information about animal exposure to dietary supplement ingredients may be in the form of formal studies, such as traditional toxicity studies, safety pharmacology data, or observations from clinical veterinary medicine. Because dietary supplement ingredients are not required to undergo formal animal toxicity testing before marketing, extensive toxicity studies are uncommon, but limited amounts of animal data for a number of dietary supplement ingredients are available in the scientific literature. Despite the challenges of dealing with incomplete data, available animal data warrant attention when assessing risk of dietary supplement ingredients.
Animal studies are powerful because controlled studies can be conducted to predict effects that might not be detected from customary use by humans until they result in overt harmful effects. Animal studies are especially useful in detecting effects of chronic exposures and effects on reproductive and developmental processes because epidemiological methods of studying humans are especially problematic in these areas. The ability to administer agents to animals during their entire lifespan enables scientists to ascertain the potential toxic effects that may arise for long-term (chronic) exposure. Animal studies thus serve as important hypothesis generators and may be sufficient to indicate potentially unreasonable risk to human health, which justifies their use in evaluating the risks of dietary supplement ingredients to humans.
In general, adverse effects observed in well-designed and conducted animal studies should be treated as if they occur in at least some members of the human population, assuming humans receive a sufficiently high dose. With some notable and important exceptions, the biological factors affecting the capacity of chemical substances to cause toxicity are broadly similar across mammalian species. While discussed in detail in Chapter 5, the general spectrum of concern related to animal data is described in Table 3-6, based on the relative seriousness of adverse effects seen in animal studies (Box 3-4).