a nonlinear model that contains a linear model as a particular case) will always result in a BMDL at least as small as that resulting from a less flexible model (e.
81 1 Thyroid indicator BMD BMDL BMDL K (a) All data FTI 67 24 1.
Using the BMDL
or BMCL as the point of departure in the risk assessment of noncarcinogenic compounds rather than the BMD or BMC central estimate is generally characterized as a conservative assumption (in the health-protective sense).
The second is based on the asymptotic chi-square distribution of the likelihood ratio statistic, which Crump (12) recommends for computing the BMDL
because it is more robust than MLE.
However, BMDF and BMDL
T values of other 8 subjects which have regular menstrual period were respectively -1,7 and -1,5.
Researchers typically calculate a BMDL
by focusing on data sets for a single chemical at a time.
The final model and associated BMD and BMDL
for each dose-response set was selected according to the following criteria.
Potential advantages of the BMDL
relative to the NOAEL include the use of all available data in its determination and avoidance of the restriction that it be equal to one of the experimental doses.
is the one-sided lower 95% confidence limit, equivalent to a 90% two-sided confidence limit.
EPA calculated a 95% lower one-sided confidence limit on the BMD (BMDL
) of 2 [micro]g/kg/day, whereas the CalEPA derived a BMDL
was calculated using the profile likelihood method (Crump 1995; Filipsson et al.
In the risk assessment, we used the BMDL
as the point of departure because it takes into consideration the limited sample size of the study and the variability exhibited in the data.