Exposure time is the period over which the test agent is administered; if administration was 5 times a week for 40 weeks, for example, the exposure time is 40 weeks. Experiment time is the total time on test; it is not the age of the animals. It is measured from the start of the experiment to the time of death of the last dosed animal. Both times are always reported in the same units. When both are less than 100 weeks, exposure and experiment time are reported as “w” for weeks; when greater than this, “m” for months is used. For tests in long-lived experimental animals like dogs and nonhuman primates, “y” for years may also be used. When exposure time and experiment time are equal, then the duration of dosing was for the entire experiment. Additional information about dosage in the units administered, the pattern of dosing, and survival for each experiment is reported in the Supplementary Dataset.