Carcinogenic risk estimation various models

The fact is scientists do not know the dose—response relation at very low risks for any carcinogen. The various hypothesized relationships have different degrees of scientific support but none has been documented with anything like the degree of rigor usually sought by scientists. Moreover, different low dose extrapolation models can yield markedly different estimates of risk, with variations of 100- or 1000-fold not unusual. Here s another issue left to the unhappy risk assessor to resolve. 

---