Several precautions are taken to ensure that contamination of the main experiments by small amounts of benzpyrene or dibenzanthracene does not occur. The results of the calibration experiments to date are given in Table 12. The calibration experiments are, to date, running as might have been expected. For example, in Experiment BO, the 26 week treatment with the skin carcinogens is giving rise to more tumours than is the 13 week treatment whilst benzpyrene appears to lead to more tumours than does dibenzanthracene. Consider an imaginary mouse-painting experiment in which groups of identical mice continuously enter the population at small intervals of time.
Mice leave the experiment either because they die, or because they get tumours.
The average age of the mice which develop tumours. It is clearly not possible to carry out a steady state experiment in practice. However, it is suggested that it is possible to synthesise the steady state experiment from the results which are obtained from the usual bioassay experiment. At present, therefore, consider in more detail the imaginary steady state experiment. The total number of healthy mice is made up by mice of all age groups.