Basis for a Dose-Response Assessment

1 Basis for a Dose-Response Assessment. At a minimum, the results of the hazard identification process are available as a basis for dose-response assessment. Additional data obtained from known occupational exposures or studies conducted specifically for the purpose of dose-response assessment may also be available. 

If available, adequate human epidemiologic data are preferred over data from animal studies. If there are adequate data on doses received in a well-designed and well-conducted negative epidemiologic study, it may be possible to obtain an upper-bound estimate of the response probability from that study. Estimates of upper bounds obtained from negative studies on animals, if available, also should be presented as supporting evidence. 

In the absence of appropriate human studies, data from an animal species expected to respond most like humans should be used, if this 

Chemical agents are not expected to increase the incidence of cancer in all, or even many, organs or tissues. Rather, it is thought that certain agents can cause an increase in the incidence of cancer in a single organ or, in some cases, two or three related tissues. This 

Since responses at the low dose levels of concern in routine exposures of the public cannot be measured directly in animal or human epidemiologic studies, a number of approaches have been developed to extrapolate from high to low doses. Different extrapolation approaches may fit the observed data reasonably well but lead to large differences in the projected responses at low doses (see Section 3.2.1.5.2). 

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