For chemicals for which estimates of short
t1/2
elim exist (e.g., extrapolated from animal
studies or derived from highly exposed individuals),
the CSTD half-life tool will provide
a good estimate of t1/2
elim based on CSTD
from the later stage of the transition period.
In contrast, for chemicals that may have
long t1/2
elim values, t1/2
elim can be derived only
with dynamic PPK models combined with
sequential sets of cross-sectional data. This
approach requires long-term planning since
cross-sectional data sets are