Comments	Action/Response	2nd comments 	Action / Response 2	Page #

Analyses of fetal examination data should combine incidences of related
findings to better show trends that may be treatment related. Examples
of related findings that could be combined include: sternebral deficits
such as asymmetric, bifid, hypoplastic, and dumbbell shaped; rudimentary
and well-formed lumbar ribs; and ossification and cartilaginous
variations of thoracic centra su.ch as bifid, hypoplastic, and dumbbell
shaped.	Fetal examination data reanalyzed

	A number of combined endpoint analyses are shown in Appendix K.  There
can be multiple opinions as to which endpoints should be combined for
analysis.  Further into the program, perhaps at the juncture for risk
assessment or publication, API should re-assess what types of combined
endpoints appear to be most appropriate for interpretation of the
overall program.	See draft final report	3-9 – 3-11 and Appendix K

Page 3-4, Feed and Water:

Copies of the feed and water analyses should be included in the report
as appendices.	Feed and water analyses added

	OK, but this needs to be mentioned on p. 3-4 (p. 17) in the text	See
draft final report 	Appendix M



Page 4-6, Skeletal Observations:

Text, first paragraph: The statistically significant trend analysis for
rudimentary lumbar ribs must be addressed. Please also compare the data
to the laboratory historical control range for "dumbbell-shaped thoracic
vertebral centra anlage," for dismissal. Also, "dumbbell” is
misspelled.	New statistical analyses does not have linear trend
analyses.  Comparison to historical control added.

	OK- but why was this deleted?  If this was part of the original
procedures, isn’t it necessary to include the results?	See draft final
report	4-3













Maternal Toxicity







Reviewer Goldsworthy agreed with the authors that the NOAEL for maternal
and developmental toxicity is 20,000 mg/m3.   However, the report was
subsequently revised, and the conclusions regarding maternal toxicity
changed.  The final draft report now considers 20,000 mg/m3 to produce
maternal toxicity, and the NOAEL for maternal toxicity in the current
version of the report is 10,000 mg/m3.    

	See draft final report



	The final draft report reports a statistically significant decrease in
maternal body weight gain and food consumption on gestation days 8-11
(page 25 of 267) at 20,000 mg/m3.  The report also states, “there was
a statistically significant linear decrease in body weight change in the
treated groups for this interval.”  

	See draft final report



	The authors should be encouraged to re-examine the individual animal
data relative to maternal body weight gain and food consumption on
gestation days 5-8 and 8-11.  Specifically, at 20,000 mg/m3, two dams
had a very unusual pattern of weight loss and weight gain, and these
dams appear to be outliers.  Dams IGK333F and IGK350F lost 34 and 31
grams of body weight, respectively, on gestation days 0-5, before
exposure to the test material began on gestation day 5.  On gestation
days 5-8, which were the first days of exposure, these dams gained 53
and 54 grams, respectively.  Inexplicably, both of these animals had
relatively low food consumption on gestation days 0-5 and 5-8.  Similar
body weight gain values were found in two dams at 10,000 mg/m3, but
these values were considered “spurious” and excluded from the
statistical analyses.  In other words, the treatment of the
“outliers” differed at the two doses.  

	See draft final report

	









Fetal Skeletal Examination





On page 27, the final draft report indicates a statistically significant
increase in “dumbbell shaped vertebral centra” at 10,000 mg/m3. 
But, Appendix H (Individual Fetal Observations) does not indicate a
statistically significant increase.  Appendix K (Statistician’s
Report) describes a statistically significant increase in “dumbbell
shaped vertebral centra” but does not show a statistically significant
increase in the tables.  Appendix K (page 231) also says there was a
statistically significant increase in “dumbbell shaped vertebral
centra anlage” at 2000 mg/m3, but this is not identified in the tables
or the report text.  While this does not appear to be a
treatment-related effect since it was not observed at the highest
exposure level, it is important to report results consistently. 

	See draft final report	Page 27







211 (b) Research Group QA/QC Reviewer





The following items require further consideration:





Compliance Statement:

Since it was the sponsor’s responsibility to maintain the method of
synthesis, fabrication, or derivation of the test fuel, and this has not
been completed, it must be included in the sponsor’s compliance
statement.	This is not a compliance issue.  The Sponsor has provided the
location of the information and a statement has been added in the test
substance section

	It is a compliance issue as the study was non-compliant when it was
being conducted.  

	See draft final report	3-1

Page viii, Personnel:

Is a compound preparation supervisor an appropriate person to have
listed under personnel? Did this person actually work on this study?	No
change.  It is an SOP requirement.

	OK, Previous Lab Director and QA Director/auditor should be listed as
well.	See draft final report	Page viii

Appendix B, Page B-9:

Under Animal No. 441F, “Discharge” is mistyped.	Corrected   	  Still
mistyped.	See draft final report	B-9

Appendix H, Page H-33:

For animal 338F fetus 3, it appears that finding “b” should indicate
thoracic vertebrae T11, 12, not T8, 9. For fetus nos. 9 and 11, the
skeletal findings need to be verified. The reported findings do not
appear to agree with what is documented in the raw data.	Table corrected

	T11, 12 reported OK.  Virtually all other fetuses findings have changed
from original.	See draft final report	H-33

Appendix H, Page H-37:

For animal 364F fetus nos.5 and 11, the skeletal exam raw data show that
vertebral findings “d” and “e” involved T11, 12. Only T12 is
indicated in the report appendix.	Table corrected  	Only T12 is
indicated and virtually all other fetus findings have changed.	See draft
final report	H-37



Appendix H, Page H-38:

For animal 358F fetus 5, the skeletal exam raw data show that the
vertebral findings “b” and “c” involved T11, 12. Only T11 is
indicated in the report appendix.

	Table corrected  	The “c” finding for fetus 1 has been deleted and
additional findings for fetus 5 have been added.  	See draft final
report	H-38



The F/I, R/I, and D/I Transformations have been added to the report
without including their definitions on the Abbreviations Sheet (page
5-2).

	See draft final report	5-2



Appendix K, Stat Report values do not always coincide with the way
results are reported in Appendix H.  Head malformations, retinal fold,
malpositioned nasal septum, anophthalmia listed in Appendix K are listed
in Appendix H as Visceral malformations.  Consequently visceral
malformations in Appendix K do not include the head malformations
because they are summarized separately.  

	See draft final report	Appendix K



The finding of ‘dilated cerebral ventricle’ is listed in Appendix H
as a visceral variation while it is reported in Appendix K as Head
Malformation.  

	See draft final report	Appendix H & K



Hydrocephaly does not appear to have been included in Appendix K for
evaluation either alone or grouped for summary purposes. 

	See draft final report	Appendix K









211(b) Toxicology Research Group

MTBE Rat Developmental Toxicity Study Report 

Reviewer Checklist 2 – Additional Comments

				  PAGE  1 	                                                         
                                  DATE \@ "M/d/yyyy"  4/4/2008 

 

