[Federal Register Volume 64, Number 107 (Friday, June 4, 1999)]
[Rules and Regulations]
[Pages 29949-29958]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-14147]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 172
[Docket No. 91F-0228]
Food Additives Permitted for Direct Addition to Food for Human
Consumption; Sucrose Acetate Isobutyrate
AGENCY: Food and Drug Administration.
ACTION: Final rule.
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SUMMARY: The Food and Drug Administration (FDA) is amending the food
additive regulations to provide for the safe use of sucrose acetate
isobutyrate (SAIB) as a stabilizer of emulsions of flavoring oils used
in nonalcoholic beverages. This action is in response to a petition
filed by Eastman Chemical Co.
DATES: Effective June 4, 1999; written objections and requests for a
hearing by July 6, 1999. The Director of the Office of the Federal
Register approves the incorporation by reference in accordance with 5
U.S.C. 552(a) and 1 CFR part 51 of certain publications in
Sec. 172.833(b) (21 CFR 172.833(b)), effective June 4, 1999.
ADDRESS: Written objections may be sent to the Dockets Management
Branch (HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm.
1061, Rockville, MD 20852.
FOR FURTHER INFORMATION CONTACT: Blondell Anderson, Center for Food
Safety and Applied Nutrition (HFS-206), Food and Drug Administration,
200 C St. SW., Washington, DC 20204, 202-418-3106.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Introduction
II. Evaluation of Safety
A. Estimated Daily Intake for SAIB
B. Evaluation of Safety Studies on SAIB
1. Pharmacokinetics and Metabolism Studies
2. Genotoxicity Studies
3. Reproduction and Developmental Toxicity Studies
a. Three-generation reproduction with teratology phase in
rats (Appendix 86)
b. Teratology study in rabbits (Appendix 87)
c. Agency conclusions regarding reproduction and
developmental toxicity studies on SAIB
4. Two-Year Carcinogenicity Studies
a. Rat study (Appendix 95)
b. Mouse study (Appendix 96)
5. Concerns Regarding Altered Liver Function
a. Liver effects in the SAIB-treated animals
i. Short-term studies
ii. Subchronic oral toxicity studies on SAIB (Appendices
63, 64, 65, 67, 68, 69, and 700
iii. Specific liver function tests
b. Studies resolving the altered liver function issue
i. One-Year chronic toxicity studies
ii. Human clinical studies
c. Agency conclusions regarding the altered liver function
issue
C. Acceptable Daily Intake for SAIB
III. Conclusion
IV. Environmental Effects
V. Paperwork Reduction Act of 1995
VI. References
VII. Objections
I. Introduction
In a notice published in the Federal Register of September 5, 1991
(56 FR 43927), FDA announced that a food additive petition (FAP 1A4266)
had been filed by Eastman Chemical Co. (Eastman), P.O. Box 511,
Kingsport, TN 37662, proposing that the food additive regulations be
amended in part 172 (21 CFR part 172) to provide for the safe use of
SAIB as a stabilizer of emulsions of flavoring oils used in
nonalcoholic carbonated and noncarbonated beverages.
SAIB is the chemical alpha-D-glucopyranoside, O-acetyl-tris-O-(2-
methyl-1-oxopropyl)-beta-D-fructofuranosyl, acetate tris(2-methyl
propanoate). It is also referred to as sucrose diacetate
hexaisobutyrate, sugar esters of fatty acids, and sucrose esters of
fatty acids.
SAIB is a slightly yellow, clear, viscous liquid, practically
odorless, with a bitter taste (not apparent at the levels used in the
regulated application). The compound is produced by reaction of food
grade sucrose with acetic anhydride and isobutyric anhydride in the
presence of a catalyst. The product is purified by molecular
distillation.
In support of safety for the proposed use of SAIB, Eastman
submitted toxicity studies performed in a variety of species. Those
studies included: Absorption, metabolism, and elimination studies
(rats, dogs, rabbits, monkeys, and humans); short-term (7 to 56 days)
studies (rats, dogs, and monkeys); a palatability study (mice);
subchronic (90 days) studies (rats and dogs); chronic studies (rats and
monkeys); carcinogenicity studies (rats and mice); reproduction studies
(rats); teratology studies (rats and rabbits); genotoxicity tests;
liver function studies (rats, dogs, monkeys, and humans); and clinical
studies (humans).
The one concern raised by FDA's evaluation of the SAIB data base
was some liver effects, which were observed in the short-term and
subchronic studies. These effects were observed primarily in SAIB-
treated dogs; for example, decreased clearance rates for
bromosulfophthalein (BSP) and indocyanine green (ICG) from the blood,
and increased serum alkaline phosphatase. To further evaluate these
liver effects, the petitioner performed special liver function tests
(BSP and ICG clearance tests) in rats, dogs, monkeys, and humans. The
BSP clearance test was also performed in monkeys and rats after
exposure to SAIB for 1 year in order to demonstrate that the liver
effects were not observed in these SAIB-
[[Page 29950]]
treated animals after long-term repeated exposure. The results from
these studies and results from other studies that were pivotal to the
safety decision for the proposed use of SAIB in beverages are discussed
in section II.B of this document.
II. Evaluation of Safety
In order to establish, with reasonable certainty, that a new food
additive is not harmful under its intended conditions of use, FDA
considers the projected human dietary exposure to the additive, the
additive's toxicological data base, and other relevant information
(such as published literature) available to the agency.
A. Estimated Daily Intake for SAIB
In determining whether the proposed use of an additive is safe, FDA
typically compares an individual's estimated daily intake (EDI) of the
additive to the acceptable daily intake (ADI) established by the
toxicological database. The EDI is determined by projections based on
the amount of the additive proposed for use in particular foods and on
data regarding the consumption levels of these particular foods.
The proposed levels of use for SAIB in beverages (up to 300 parts
per million (ppm)) are supported by functionality and stability data
presented in the petition. The agency commonly uses the EDI for the
90th percentile consumer of a food additive as a measure of high
chronic exposure. For the requested food use of SAIB, the agency has
estimated the lifetime exposure for 90th percentile consumers, 2 years
old and older (all ages), to be 0.17 gram per person per day (g/p/d).
The corresponding mean intake is 0.082 g/p/d (Ref. 1).
B. Evaluation of Safety Studies on SAIB
The principal studies relevant to the safety evaluation of the
petitioned use of SAIB were performed in several animal species as
mentioned in section I of this document. The individual studies are
identified by an Appendix number in this document, as designated by
Eastman in the SAIB petition.
1. Pharmacokinetics and Metabolism Studies (Appendices 16, 17, 18, 19,
22, 23, 24, 25, 26, 27, 29, and 31)
The pharmacokinetics and metabolism studies on SAIB were performed
with rats, dogs, and humans in order to compare the absorption,
metabolism, and excretion of the food additive in animal models to that
seen in humans. Results from these studies showed the following
similarities and differences in the pharmacokinetics and metabolism of
SAIB in the test subjects:
(1) There were quantitative differences in the amounts of
administered SAIB that were absorbed by rats, dogs, and humans. Rats
and humans absorbed greater amounts of SAIB from the gastrointestinal
tract compared to dogs. In rats and humans, the majority of the orally
administered SAIB was eliminated in expired air, whereas in dogs, the
majority of SAIB was eliminated in the feces;
(2) Dogs excreted a greater proportion of the absorbed SAIB in the
bile compared to rats. The excreted materials in the bile of the dog
were identified as either unchanged SAIB or higher acylated sucrose
molecules. Lower acylated sucroses were identified in the bile of rats;
and
(3) The urinary metabolites of SAIB in rats and humans were more
similar qualitatively than those between dogs and humans. Higher
acylated sucroses were identified as the primary metabolite in the
urine of dogs. In the urine of rats and humans, only lower acylated
sucroses and free sucrose were identified. Free sucrose was not found
in the urine from dogs. These data show that more deacylation of SAIB
occurs in rats and humans than in dogs.
The patterns of absorption, metabolism, and elimination are more
similar for rats and humans than for dogs and humans. Therefore, the
agency concludes that the rat is more appropriate than the dog to model
the metabolic disposition and fate of SAIB in humans (Refs. 2, 3, 4,
and 5).
2. Genotoxicity Studies (Appendices 88, 89, 90, 91, 92, 93, and 94)
SAIB was subjected to the following battery of studies to evaluate
its genotoxic potential in prokaryotic and mammalian species: Ames
Test, Chinese Hamster Ovary Cells/HGPRT Forward Mutation Assay, In
Vitro Cytogenetic Chromosomal Aberration Assay, Unscheduled DNA Assay,
and Dominant Lethal Assay. In the absence of bioassay data, these tests
are often used to predict the carcinogenic potential of the test
compound. However, in the case of SAIB, carcinogenicity bioassays are
also available.
SAIB was shown to be nonmutagenic in the Ames test, with or without
metabolic activation (Appendices 88, 89, and 90) (Refs. 6 and 7). The
compound did not induce changes in mutation frequency in the Chinese
Hamster Ovary Cells/HGPRT Forward Mutation Assay (Appendix 91) (Ref.
8). Chromosomal aberrations were not induced in Chinese hamster ovary
cells (Appendix 92), thereby demonstrating that SAIB is not clastogenic
(Ref. 9).
Results from the Unscheduled DNA Assay (Appendix 93) were negative
regarding any significant increases in nuclear labeling or unscheduled
DNA synthesis in rat primary hepatocytes treated/incubated with SAIB
(Refs. 9, 10, 11, and 12). The Dominant Lethal Assay (Appendix 94) did
not show any significant effects on early fetal deaths per pregnancy in
rats.
Based upon the negative mutagenic and clastogenic findings in the
genotoxicity studies, the agency concludes that SAIB is not genotoxic
under the test conditions of these studies (Refs. 5, 6, 7, 8, 9, 10,
11, 12, 13, and 14).
3. Reproduction and Developmental Toxicity Studies (Appendices 86 and
87)
The objectives of the reproduction and developmental toxicity
studies were to evaluate the toxic potential of SAIB on the
reproductive system of mature rats (males and females) as well as
postnatal maturation of reproductive functions of offspring through
three successive generations. Assessment of the potential effects of
the food additive on the developing fetus was the objective of the
teratology studies.
a. Three-generation reproduction with teratology phase in rats
(Appendix 86). In this study, groups of Fischer F344 rats (three
generations: F0, F1, and F2 males and
females) were administered SAIB in the diet at dose levels of 0, 0.5,
1.0, or 2.0 g per kilogram body weight per d (g/kg bw/d). Parental
(F0) males were fed SAIB for 10 weeks prior to mating;
F0 females were fed SAIB for 2 weeks prior to mating, and
throughout mating, gestation, and lactation until the time of necropsy.
F1 and F2 males and females were exposed to SAIB
in utero; during their lactation and weaning periods as well as
throughout their mating, gestation, and lactation periods for
respective F2 and F3 litters. The F1
males and females were bred twice in succession to produce
F2a and F2b pups. For each generation, the
following reproductive parameters were examined: Mating indices,
fertility indices, gestation indices, gestation length, number of
corpora lutea, implantation efficiency, and number of early or late
resorptions. Litters from the F1 and F2
generations were examined for the number of dead pups (day 0), number
of live offspring per litter, sex ratios, pup survival percentages, pup
weights, and physical abnormalities. Macroscopic examinations of the
corpora lutea and implantations were performed on the F2
dams that were
[[Page 29951]]
sacrificed on day 14 of gestation period of the F3
generation. For the teratology phase of this study, macroscopic
examination of the number and distribution of fetuses in the uterine
horn and the number of resorptions and corpora lutea were performed on
F1 dams that were sacrificed on day 20 (during gestation) of
the F2b generation. The pups from these dams were examined
for any soft-tissue or skeletal malformations.
The agency observed no reproductive or developmental toxicities in
three successive generations of rats that were exposed to SAIB at
levels up to 2.0 g/kg bw/d. There was a trend towards decreased
fertility with increasing dose of SAIB in the females of the
F1 generation during the breeding for the F2a
litters. The agency does not consider this trend to be treatment-
related because there were no significant decreases in fertility
observed in the F0 females during the breeding for the
F1 litters or the F1 females during the breeding
for the F2b litters. The agency has determined that the no
observed effect level (NOEL) for this study is 2.0 g/kg bw/d, which was
the highest dose of SAIB tested in this study (Ref. 13).
b. Teratology study in rabbits (Appendix 87). New Zealand White
SPF female rabbits were divided into a control group (32 rabbits) and 3
SAIB treatment groups (16 rabbits per group). Control and treated
female groups were induced to superovulate by receiving injections of
human chorionic gonadotropin 3 weeks prior to insemination. SAIB was
administered by oral gavage, twice daily, to the treatment groups at
dose levels of 0.50, 0.85, or 1.20 g/kg bw/d on days 7 through 19 of
gestation. The control group received only the vehicle (corn oil) .
The agency concludes that in this study there were no developmental
toxicities observed in rabbits that were exposed to SAIB by gavage at
levels up to 1.20 g/kg bw/d during gestation (days 7 to 19). The agency
has determined that the NOEL for this study is 1.20 g/kg bw/d for this
study (Ref. 13).
c. Agency conclusions regarding reproduction and developmental
toxicity studies on SAIB. Based on the data obtained from these
reproduction and developmental toxicity studies on SAIB (Appendices 86
and 87), the agency concludes that the oral administration of SAIB does
not induce reproductive or developmental effects in rats when tested in
the diet at doses up to 2.0 g/kg bw/d or developmental effects in
rabbits when tested by gavage at doses up to 1.20 g/kg bw/d. Therefore,
a NOEL of 2.0 g/kg bw/d is established for SAIB based upon the highest
dose tested in the three-generation rat study (Refs. 5 and 13).
4. Two-Year Carcinogenicity Studies (Appendices 95 and 96)
The objective of the carcinogenicity studies was to study the
carcinogenic potential of SAIB when administered to rodents for 104
weeks.
a. Rat study (Appendix 95). Fischer F344 (CDF/CrlBR) rats were
randomly assigned to 5 groups that were fed a dietary mixture of SAIB
at dose levels of 0, 0.50, 1.0, or 2.0 g/kg bw/d for 104 weeks. Two
groups of rats served as duplicate controls and were fed an NIH07 diet
that had been treated with acetone only. BW data for all of the rats
were collected on day 1, at weekly intervals during the study, and on
the day of necropsy. Food consumption was recorded weekly. Hematology
measurements were performed on all rats prior to the initiation of
treatment and at the end of the study at week 104. During necropsy,
organ weight data were collected for heart, kidneys, liver, testes,
ovaries, and brain of the rats in the two control groups and in each of
the SAIB-treated groups. Macroscopic and microscopic examinations were
performed at sacrifice (week 104) on representative tissue from a
comprehensive selection of organs from all groups of rats.
Survival in the treated rats was not significantly affected by the
SAIB treatment for the 2-year exposure duration. The antemortem changes
seen in the SAIB-treated groups at termination were similar to those
seen in the concurrent control rats and represented typical changes
seen in aging rats.
Overall, SAIB did not significantly affect the final mean bw's or
food consumption of either the male or female rats during the 104 weeks
of the study. The organ weight data showed reduced brain (absolute)
weight in the 1.0 g/kg bw/d SAIB-treated females when compared to
females in group 1 controls and increased kidney-to-brain ratios in the
1.0 g/kg bw SAIB-treated males when compared to males in group 2
controls. FDA did not consider these weight differences to be
treatment-related or toxicologically significant because they occurred
sporadically among the treated groups, that is, at only one dose level
(1.0 g/kg bw/d dose) or in only one sex. There were tumors or
nonneoplastic lesions that occurred in the control and SAIB-treated
rats of this study that represented histopathological changes commonly
seen in aging rats or represented normal variation of spontaneous tumor
incidences (e.g., testicular interstitial cell tumors, mammary gland
fibroadenomas, endometrial stromal polyps, and pituitary hyperplasia).
Thus, the histopathology data showed no evidence of male or female
SAIB-treated rats with increased incidences of tumors or nonneoplastic
lesions at any organ site that were related to the feeding of SAIB
(Ref. 15).
From this study, the agency concludes that SAIB did not induce any
tumors in Fischer 344 rats that were fed diets containing up to 2.0 g/
kg bw/d of SAIB for 104 weeks. No SAIB-related histopathological
lesions were observed in the SAIB-fed rats. Thus, the NOEL for this
study is 2.0 g/kg bw/d (Refs. 5, 14, and 15).
b. Mouse Study (Appendix 96). In this study, groups of B6C3F1/Cr1BR
mice (50 per sex per group) were fed SAIB at concentrations of 1.25,
2.5, or 5.0 g/kg bw/d in an NIH07 diet for 104 weeks. Two groups of
mice served as controls and were fed an NIH07 diet that had been
treated with acetone only. BW data were collected on day 1, at weekly
intervals during the study, and on the day of necropsy. Food
consumption was recorded weekly. Hematology measurements were performed
on mice in the control and 5.0 g/kg bw group only; 10 mice per sex
prior to the initiation of treatment and 15 mice per sex during weeks
28, 53, 79, and 105. During necropsy, organ weight data were collected
for the kidneys, liver, gall bladder, and lungs of all mice.
Macroscopic and microscopic examinations were performed at sacrifice
(week 104) on representative tissue from a comprehensive selection of
organs from all groups of mice.
The study results revealed no treatment-related effects on the
survival of SAIB-treated mice in this study. All antemortem
observations seen in the SAIB-treated mice were comparable to those
seen in the concurrent controls.
Organ-to-bw ratios of the liver and lungs of the SAIB-treated mice
were not different from the respective weight ratios in the control
mice. There were some differences in the relative kidney weights in the
SAIB-treated mice compared to controls; however, these differences were
not associated with any treatment-related kidney histopathology.
The histopathology data showed an increased incidence of SAIB-
treated male mice with bronchiolar/alveolar adenomas and an increased
incidence of SAIB-treated male mice with (combined) bronchiolar/
alveolar adenomas or carcinomas when compared to control group males
(Refs. 14 and 15). The incidences of SAIB-
[[Page 29952]]
treated females with bronchiolar/alveolar adenomas or carcinomas were
comparable to incidences in control females. According to historical
control incidence data from the National Toxicology Program data base,
these incidences are within the range commonly seen in aged B6C3F1
mice. Therefore, FDA concludes that the increased incidences of SAIB-
treated mice with this tumor represent expected variations in
spontaneous incidences and were not related to the SAIB treatment
(Refs. 14 and 15). At the other organ sites, there was no evidence of
increased incidences of mice with tumors or nonneoplastic lesions that
were related to the feeding of SAIB (Refs. 14 and 15). From this study,
the agency concludes that SAIB did not induce tumors at any organ site
in B6C3F1 mice that were fed diets containing SAIB up to 5.0 g/kg bw /d
for 104 weeks. No SAIB-related nonneoplastic lesions were observed in
the SAIB-fed mice, nor was there other evidence of adverse effects in
the SAIB-fed mice at any of the tested doses. Thus, the NOEL for this
study is 5.0 g/kg bw/d (Refs. 5, 14, and 15).
5. Concerns Regarding Altered Liver Function
During the early reviews of the petition, the agency raised a
concern regarding liver effects that were observed in the SAIB-treated
animals in short-term toxicity studies (rats, dogs, and monkeys) and in
subchronic toxicity studies (rats and dogs), especially in the SAIB-
treated dogs. However, the agency could not easily determine whether
the liver effects observed in these SAIB-treated rats and monkeys were
treatment-related because of certain inadequacies in the studies, their
limited experimental designs, and the studies' short exposure
durations. These studies are discussed in section II.B.5.a of this
document. The agency also raised a concern that there were no chronic
(1 year or longer) toxicity studies on SAIB in dogs that further
examined the liver function effects.
To address these concerns, the petitioner performed BSP and ICG
clearance tests, which are specific liver function tests, with rats,
dogs, and monkeys. In addition, to address the concern regarding
possible altered liver function in chronically-exposed animals, the
petitioner performed a 1-year oral toxicity study on SAIB in monkeys;
this study included BSP clearance tests and measurements of clinical
chemistry parameters relevant to liver toxicity. The petitioner also
performed BSP clearance tests in humans that were administered doses of
SAIB up to 0.02 g/kg bw/d for 14 days to evaluate any potential effects
of SAIB on liver function in humans. These studies and the agency's
conclusions regarding them are discussed in sections II.B.5.b and
II.B.5.c of this document.
a. Liver Effects in the SAIB-treated Animals. i. Short-term Studies
(Appendices 60, 66, 71, 72, 73, 74, and 77). The following short-term
studies were designed to provide data on the short-term oral toxicity
of SAIB in rats, dogs, and monkeys with regard to potential target
organs of SAIB, as well as to determine appropriate doses for the
subchronic and chronic studies.
Rat Studies (Appendices 66 and 74). In a short-term study
(Appendix 66), SAIB was fed to groups of male and female rats at levels
of 1.0, 2.0, or 4.0 percent (equivalent to 1.0, 2.0, or 4.0 g/kg bw/d)
in the diet for 28 or 56 days. Levels of serum alkaline phosphatase
(SAP), glucose, ornithine carbamyl transferase, triglyceride,
cholesterol, and blood urea nitrogen were examined. Organ weight data
were collected only on the liver.
The limited clinical chemistry data from this study showed
decreases in blood glucose levels in female rats fed SAIB at levels of
2.0 and 4.0 percent in the diet for 56 days. The glucose levels in the
treated males were not different from comparable levels in controls for
the 56-day duration. SAP levels were not affected in the SAIB-treated
rats. There were no effects on bw or bw gain in the SAIB-treated rats.
Liver weights in these SAIB-treated rats were similar to control rats.
Also, the levels of glucose in the treated groups were not different
from controls (Ref. 16).
In another short-term study (Appendix 74), groups of rats (15 per
sex per group) were fed diets containing 0, 5,000, or 50,000 ppm
(equivalent to 0, 0.50, or 5.0 g/kg bw/d) SAIB for 3 weeks. Organ
weight data on livers from the male and female SAIB-treated rats (five
per sex per group) revealed no evidence of liver enlargement at either
of the doses of SAIB. In addition, SAIB did not affect bw gain or food
consumption in this study (Ref. 3).
Dog Study (Appendix 77). In this study (Appendix 77), six male
beagle dogs were initially fed a ground chow diet without SAIB (control
diet) daily for 3 weeks. For the next 3 to 4 weeks, the six male dogs
were fed a ground chow containing 5-percent (equivalent to 1.25 g/kg
bw/d) SAIB. ICG clearance tests were performed on four of the six dogs
at week 3 of this 5-percent SAIB feeding period. After the 3 or 4 weeks
feeding period of SAIB, the dogs were returned to control diet for an
additional 8 weeks (91st day). ICG clearance tests were performed on
week 3 and 6 of this 8-week control diet feeding period. On the 88th
day, 4 of the 6 dogs were returned to a diet containing 5-percent SAIB
for 1 day. After this 1-day SAIB feeding, SAP measurements and ICG
clearance tests were performed on the six dogs. This study did not have
a group of dogs that served as concurrent controls nor were pretest ICG
baseline values determined. Instead, the data from this study were
compared to previously reported laboratory data for ICG clearance in
normal beagle dogs.
The results of this study showed decreased clearance of serum ICG
(half-lives (t1/2)\1\ of 17.0 to 40.0 minutes) in dogs that
were fed 5-percent SAIB for 3 weeks compared to ICG clearance in normal
dogs (t1/2 of 4.2 to 8.1 minutes). ICG clearance in the
SAIB-treated dogs had returned to normal by day 84 after these dogs
were returned to control diets without SAIB. Five of six dogs had
increased SAP levels at the end of the 4-week SAIB feeding period that
were four to seven times greater than pretest values.
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\1\ Half-life(t1/2) is the time required for the
serum ICG concentrations to be reduced by one half.
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Blood glucose levels decreased (25- to 57-percent reductions) in
all of the dogs at the end of the 4-week SAIB treatment period compared
to pretest average values. However, blood glucose levels monitored at
the end of the recovery phase of the study were reversed and were
comparable to the pretest values. Ornithine carbamyl transferase and
blood cholesterol levels also increased during the SAIB exposure
period. Other blood parameters measured in these dogs (hemoglobin,
hematocrit, white blood cell counts (five out of six dogs), serum
protein, and blood urea nitrogen) were not affected by the 5-percent-
SAIB treatment. The 5-percent SAIB treatment had no effect on body
weight, food consumption, or organ weights (only liver and kidney were
measured) in the dogs for the 4-week period (Ref. 3).
Monkey Studies (Appendices 60, 71, 72, and 73). In a short-term
study (Appendix 60), SAIB was administered by oral intubation (in an
orange juice concentrate) to four monkeys (two per sex) as a single
dose that started at a dose of 1.25 g/kg bw, increased by increments of
2-fold (72-hour intervals between doses), and ended at a dose of 20 g/
kg bw over a dosing period of 14 days. All of the SAIB-dosed monkeys
survived the study. Slight to moderate watery, yellow stools were
observed in some of the monkeys administered SAIB at doses of 1.25 g/kg
bw (one male, two females), 2.5 g/kg bw (one male, one female), and 5.0
g/kg bw (one female).
[[Page 29953]]
Large amounts of watery yellow stools and emesis were observed in a
monkey that received a SAIB dose of 5.0 g/kg bw dose. Gross postmortem
examinations of the four monkeys after the last dosing of SAIB revealed
no effects that were attributable to the SAIB administration (Refs. 2
and 17).
In a two-part range-finding study (Appendices 71 and 72), SAIB was
administered by oral intubation to groups of monkeys (one per sex per
group) at dose levels of 0, 0.5, 1.0, 2.0, 5.0 or 10.0 g/kg bw/d for 15
days. Incidences of soft, loose stools were observed in the SAIB-dosed
groups (1.0, 2.0, and 10.0 g/kg bw/d doses), as well as in the control
male and female groups. At the termination of the study, SAP levels in
the males of the 10.0 g/kg bw/d dose group and the females of the 5.0
and 10.0 g/kg bw/d dose groups were increased compared to their
respective controls. Pretest alkaline phosphatase levels in the SAIB-
dosed groups were also higher than pretest levels of the controls.
Decreased BSP clearance was observed in 8 out of the 10 treated
monkeys. Electron microscopy was performed only on the livers of the
control group and the high-dose group in this study. Results from the
ultrastructural analyses of the livers from the SAIB-treated monkeys
revealed increased glycogen, large glycogen aggregations surrounded by
scant smooth endoplasmic reticulum, and decreases in the amounts of
smooth endoplasmic reticulum (Refs. 2, 3, and 17). While these effects
in the SAIB-dosed monkeys suggest suppressed liver function, the agency
could not determine the toxicological significance of these effects
because of the small group sizes (Refs. 2, 3, and 17).
In another exploratory study (Appendix 73), groups of monkeys (one
per sex per group) were administered SAIB (in corn oil) orally by
gavage at doses of 0.50, 1.45, or 2.40 g/kg bw/d for 4 weeks. Control
monkeys received only the vehicle (corn oil) by gavage. BW gains were
comparable in all of the groups except for the high-dose female monkey,
who lost weight (12-percent loss) over the 4-week study duration.
Reduced food consumption was reported for this high dose female monkey.
SAP levels were increased 8-to 78-percent in the treated groups for
both sexes except for the one male in the high-dose (10 g/kg bw dose)
group. Values reported for erythrocyte counts, hemoglobin, and
hematocrits were low for all of the females in both the treatment
groups and the control group. BSP clearance rates in these monkeys were
normal. Clinical biochemistry parameters related to liver and kidney
functions were also normal in the dosed monkeys (Refs. 3 and 17).
Agency conclusions regarding short-term studies on SAIB. The
agency's overall review of the data from the preceding short-term
studies (see section II.B.5.a.i of this document) established the
following: (1) Decreased glucose levels in rats that were fed SAIB at
levels of 2.0 and 4.0 g/kg bw/d for 56 days; (2) decreased ICG
clearance rates, increased SAP levels, and decreased blood glucose
levels in dogs that were fed 1.25 g/kg bw/d SAIB for 4 weeks; and (3)
increased BSP retention and increased SAP levels in monkeys that were
administered SAIB by gavage at dose levels of 5 and 10 g/kg bw/d for 15
days. Based on these observed effects, the agency concludes that the
liver is a target organ for the toxicity of SAIB. However, because of
the short exposure durations and limited experimental designs of these
studies, the agency concludes that these studies are inadequate to
resolve concerns regarding the observed liver effects (Refs. 3 and 5).
ii. Subchronic oral toxicity studies on SAIB (Appendices 63, 64,
65, 67, 68, 69, and 70). The following subchronic oral toxicity studies
were performed in rats and dogs to examine the general systemic
toxicity of SAIB and to investigate further the liver effects of SAIB
that were observed in the short-term SAIB studies.
Rat Studies (Appendices 63, 64, and 65). In a 90-day study
(Appendix 63), groups of rats (25 per sex per group) were fed SAIB in
the diet at 0, 1, or 5 percent (equivalent to 0, 1.0, or 5.0 g/kg bw/
d). This study showed an increase (7.4 percent) in the relative liver
weights of the 5-percent SAIB-treated female rats compared to the
control females; liver weights in SAIB-treated males were not affected.
Kidney weights in the SAIB-treated groups were not different from the
kidney weights of the control rats. Final bw's were slightly decreased
(3 to 4 percent) in only the males of the 5-percent dose group. No
differences were observed in the final bw's of the males in the 1-
percent dose group or the females in all of the dose groups when
compared to respective controls. BW gain in all of the female treatment
groups was comparable to the female control groups. Overall, feed
intakes and feed efficiencies appeared to be similar across treatment
and control groups for both sexes (Ref. 16).
In another 90-day study (Appendix 64), groups of rats (10 per sex
per group) were fed SAIB in the diet at levels of 0, 0.38, 1.88, or
9.38 percent (equivalent to 0, 0.38, 1.88, or 9.40 g/kg bw/d). A slight
increase in the mean hemoglobin values and a tendency toward
leukocytosis (increased white corpuscle counts) were observed in
treated rats relative to control rats. SAP levels and BSP clearance
rates were not evaluated in this study. BW gains in the SAIB-treated
males were slightly decreased (8 to 11 percent) compared to control
males; in treated females, bw gain was not affected. Liver, kidney,
lung, gonad, spleen, and heart weights (relative and absolute weights)
of the SAIB-treated rats were not significantly different from the
respective organ weights of the control rats.
Data from the limited histopathological analyses showed an
increased incidence of clear vacuoles (fat vacuoles) in the livers of
all of the SAIB-treated rats with the greatest increase being seen in
the 1.88-percent SAIB group (Ref. 16).
In a 12-week study (Appendix 65), groups of rats (20 per sex per
group) were fed SAIB at doses of 2.5, 5.0, or 10 percent (equivalent to
2.50, 5.0, or 10.0 g/kg bw/d) in the diet. SAIB-treated male rats in
this study showed decrements in weight gain at all dose levels compared
to controls; weight gains in the SAIB-treated female rats were not
affected. There was a significant decrease in SAP levels in females
treated with 10-percent SAIB. Urinary ascorbic acid levels were
substantially decreased (47 percent in males and 64 percent in females)
in the 10-percent SAIB group relative to controls. There were no
increases in carboxyl esterase levels in any of the SAIB-treated rats.
Neither liver weights nor the ultrastructure of the livers in the SAIB-
treated rats were affected during the study. Biochemical analyses
performed on the livers of rats in the control and 10-percent SAIB
groups showed increases in liver glycogen in the 10-percent SAIB group
(in both sexes) as well as significant increases in the water content
of the livers in the males of the 10-percent SAIB group (Ref. 16).
Because of inadequacies in data analyses and reporting (e.g.,
limited statistical analyses and incomplete histopathology data) in the
subchronic rat studies, the agency could not reach a conclusion as to
whether there were treatment-related liver effects in the SAIB-fed rats
of these studies. The results from these studies did show: (1)
Significantly increased (relative to controls) relative liver weights
in rats (females only) that were fed 5-percent SAIB, and (2) increased
glycogen content and increased water content (males only) in the livers
of rats (both sexes) fed 10-percent SAIB relative to controls (Ref. 5).
[[Page 29954]]
Dog Studies (Appendices 67, 68, 69, and 70). In a 12-week study
(Appendix 67), groups of dogs (four per sex per group) were fed diets
containing 0, 0.2, 0.6, or 2.0 percent (equivalent to 0, 0.05, 0.15, or
0.5 g/kg bw/d) SAIB. This study showed increases in SAP levels in the
SAIB-treated male dogs, with a two-fold increase in the 2.0-percent
dose group. At the end of the study, relative liver weights of male and
female dogs fed SAIB at the 0.6-percent and 2.0-percent dose levels
increased compared to the respective control groups. Relative weights
of the other organs that were examined in the study (kidney, spleen,
brain, gonads, adrenals, thyroids, and pituitary) did not differ
significantly from respective relative organ weights of controls.
Survival, hematology parameters, and urine parameters tested in the
SAIB-treated dogs were also not significantly different from controls
(Ref. 18).
In another subchronic study (Appendices 68 and 69), groups of dogs
(six per sex per group) were fed dog chow containing 0-, 0.5-, 1.0-,
2.0-, or 4.0-percent (equivalent to 0, 0.13, 0.25, 0.50, or 1.0 g/kg
bw/d) SAIB for 12 weeks followed by a 3-week recovery period, during
which the dogs were fed a chow diet that did not contain SAIB. During
the 12-week treatment period and the 3-week recovery period of the
study, the control group received a basal chow meal without SAIB.
During the 12-week exposure period, all of the dogs in this study that
were fed SAIB (all doses) exhibited significant increases (3- to 7-
fold) in serum BSP concentrations compared to control dogs. BSP
retention data collected during the 3-week recovery period without SAIB
showed a reduction in BSP plasma levels in the 4-percent SAIB-treated
dogs to levels that were similar to pretest values and those seen in
control dogs (Appendix 69).
Relative liver weights increased in the male dogs fed SAIB at
levels of 1.0 and 2.0 percent in the diet; relative liver weights in
the 0.5-percent SAIB-treated males were not different from controls.
Relative liver weights in the SAIB-treated female dogs (all groups)
were not significantly different from control females. Absolute liver
weights were significantly increased in SAIB-treated males at dose
levels of 0.5, 1.0, and 2.0 percent. Liver weights of the 4.0-percent
male dose group were not analyzed at the time that the 1.0 and 2.0-
percent male dose groups were analyzed; instead, this dose group was
held for 3 additional weeks for a recovery phase of the study. At the
end of the this 3-week period (recovery phase), absolute and relative
liver weights of the 4-percent male dose group were also significantly
increased when compared to control liver weight values measured at the
end of the 12-week treatment phase. This 3-week recovery phase of the
study did not include a comparable control group of dogs that was held
for the additional 3 weeks after the treatment phase.
Data from liver biochemistry analyses showed significantly
increased liver glycogen in all of the SAIB-treated groups,
significantly increased liver lipid content in all of the dogs fed 2.0-
percent SAIB, and significantly increased liver carboxyl esterase
levels in all of the dogs fed 4.0-percent SAIB. Total protein levels in
the liver were greatly reduced in all of the SAIB-treated groups
compared to controls. Alkaline phosphatase, adenosine triphosphatase,
and glucose-6-phosphatase levels in the bile canaliculi of the livers
in all of the dose groups increased relative to controls.
Results from the microscopic (light and electron) analysis of liver
tissue samples showed dilation of the bile canaliculi, liver
hypertrophy and enlargement (males only), increased bile pigment
granules, increases in the smooth endoplasmic reticula, and prominent
Golgi bodies in the dogs fed 2-percent SAIB in the diet (Appendix 69).
In addition, the distribution and arrangement of the smooth and rough
endoplasmic reticula were altered in the 2-percent SAIB-treated dogs
(Ref. 18).
In a 91-day study (Appendix 70), a group of five dogs were fed dog
chow containing 5-percent (equivalent to 1.25 g/kg bw/d) SAIB. A second
group of five dogs served as controls and was fed dog chow containing
5-percent corn oil for the study duration. This study demonstrated that
SAIB significantly affected liver function in the five SAIB-treated
dogs, causing moderate elevations in SAP levels, prolonged ICG
clearance, and increases in the absolute and relative liver weights.
Hematological or clinical chemistry parameters examined in this study,
other than SAP, were not affected by the SAIB treatment (Ref. 3).
Based upon the data in the subchronic studies in dogs, the agency
concludes that SAIB affected liver function in SAIB-treated dogs at all
of the tested dose levels. As noted, the liver effects observed in the
SAIB-treated dogs were: (1) Increased BSP retention at SAIB doses as
low as 0.13 g/kg bw/d and up to a dose of 1.0 g/kg bw/d, (2) increased
SAP levels at SAIB doses of 0.05 g/kg bw/d and higher, (3) increased
liver weights at doses of 0.13 g/kg bw/d and higher, and (4) liver
ultrastructural changes in the 0.5 g/kg bw/d dose group (liver
enlargement/hypertrophy, increased liver glycogen deposition, increased
liver carboxyl esterase activity, and proliferation of smooth
endoplasmic reticulum). Because effects were observed at the lowest
tested dose, the agency could not establish a NOEL for the observed
liver effects in the SAIB-treated dogs in the subchronic studies (Refs.
3, 5, and 18).
Agency Conclusions Regarding Subchronic Studies on SAIB. The agency
concludes from the subchronic studies that SAIB affected liver function
in dogs when fed SAIB at doses of 0.13 g/kg bw/d up to 1.0 g/kg bw/d.
The subchronic studies in rats also suggested apparent liver
effects in rats that were fed SAIB at dose levels of 5.0 g/kg bw/d and
higher. However, because of study limitations (e.g., incomplete
histopathology data and inadequate statistical analyses), the agency
could not determine from the subchronic rat studies whether the liver
effects seen in the SAIB-treated rats were caused by the treatment with
SAIB (Refs. 3, 5, 16, and 18).
In order to investigate further the effects of SAIB on liver
function in different species, the petitioner performed specific liver
function tests in rats, dogs, monkeys, and humans. The results from
these tests are discussed in sections II.B.5.a.iii. and II.B.5.b.ii of
this document.
iii. Specific liver function tests (Appendices 75, 76, 78, 80, and
81). BSP and ICG clearance tests were performed by the petitioner in
rats, dogs, and monkeys. In these tests, BSP or ICG is administered by
injection and the clearance of these dyes from the blood is analyzed
spectrophotometrically at various time intervals up to 48 hours. In
normal subjects, generally 95 percent of the injected dye is cleared
from the blood through the liver within 30 minutes. Retention of BSP in
the blood is indicative of some form of liver dysfunction such as
hepatic degeneration/inflammatory changes, hepatic fibrosis, hepatic
cholestasis, or depressed hepatic blood flow (Refs. 19, 20, 21, 22, 23,
and 24).
Rat Tests (Appendices 75 and 76). In a 36-day study (Appendix 75),
two groups of rats (17 males per group) were fed a chow diet containing
either 4.0-percent (equivalent to 4.0 g/kg bw) SAIB in 5.0-percent corn
oil or only 5.0-percent corn oil. On days 1, 3, 5, 8, 10, 22, 26, and
36, after the start of these diets, 2 rats from each group were
selected for ICG clearance testing. ICG clearance rates in SAIB-treated
rats were not significantly different from control rats at any of the
time intervals (Ref. 3).
In a 7-day study (Appendix 76), 15 rats (5 males per group) were
fed a rodent diet containing 4-percent
[[Page 29955]]
(equivalent to 4.0 g/kg bw/d) SAIB. BSP clearance was measured in these
rats at 0, 24, and 48 hours posttreatment with SAIB. SAIB had no effect
on BSP clearance from the liver in these rats when fed for 7 days (Ref.
3).
Dog Tests (Appendices 76 and 78). In an intermittent dosing study
(Appendix 76), two male and two female dogs were serially provided, on
one dose per week, laboratory dog chow ration containing SAIB at
increasing concentrations of 0.1, 0.3, and 0.5 percent (equivalent to
dose levels of 0.03, 0.08, or 0.13 g/kg bw). The animals were fed dog
chow without SAIB on days between each dosing. BSP clearance rates for
the 4 dogs were evaluated at 24 and 48 hours following each dosing. BSP
clearance rates were also measured in each of the dogs prior to the
start of the study to determine pretest baseline values. Results from
this study showed increased BSP retention at the 24-hour time interval
in the dogs at all treatment levels (Ref. 3).
Results from another study in dogs (Appendix 78) showed that BSP
retention increased (up to seven-fold) in both male and female dogs
administered SAIB as single (oral gavage) doses ranging from 0.005 g/kg
bw to 2.0 g/kg bw. Initial increases of BSP levels were observed within
4 to 6 hours posttreatment with SAIB (Refs. 2 and 3).
Monkey Tests (Appendices 80 and 81). In a study (Appendix 80), a
group of monkeys (three males) were administered 1.0 g/kg bw of SAIB in
cottonseed oil by gavage as a single dose. A second of group of monkeys
(three males) received no treatment and served as controls. After this
dosing of SAIB, BSP clearance tests were performed. The three SAIB-
treated monkeys were given a second 1.0-g dose of SAIB after a 7-day
rest period followed by additional BSP clearance testing. The first
SAIB dosings showed an increase in the BSP level in one of the three
treated monkeys, while the second SAIB dosing resulted in an increase
in the BSP levels in a different treated monkey (Ref. 3). FDA concluded
that these results are inconclusive because of the equivocal BSP
results and the small group sizes.
In another study (Appendix 81), a group of monkeys (four males) was
administered SAIB orally by gavage at a dose of 5 g/kg bw. Another
group of four males was gavaged with corn oil and served as a control
group. BSP clearance was tested in the control and SAIB-treated monkeys
5 hours after the SAIB dosing. The group mean BSP level in the treated
monkeys was comparable to that in the control group (Ref. 3). Based
upon the results from this study, which tested a higher dose of SAIB
and had a larger group size than the above 1.0 g/kg bw monkey study
(Appendix 80), FDA concludes that BSP clearance was not affected in
monkeys that were orally gavaged with SAIB as a single dose of 1 or 5
g/kg bw (Ref. 5).
Based upon FDA's reviews of these liver function tests, the agency
concludes that liver function in dogs was clearly affected by SAIB
regardless of the doses tested (0.005 to 2.0 g/kg bw). From these
studies the agency also concludes that liver function was not affected
in either rats or monkeys at SAIB doses up to 5 g/kg bw. However,
because of the short duration of these studies, the agency was unable
to determine whether liver function would be affected in rats or
monkeys upon chronic exposure to SAIB.
In response to this concern of FDA, the petitioner conducted two 1-
year feeding studies (rats and monkeys), in which test animals were
subjected to specific liver function tests following a continuous SAIB
exposure for 1 year. Results from these 1-year studies are discussed in
section II.B.5.b.i of this document. In addition to the 1-year studies
in rats and monkeys, the petitioner conducted three human clinical
studies to investigate whether the liver function effect that was
consistently demonstrated in SAIB-treated dogs could also occur in
humans upon oral ingestion of SAIB. Results from the three human
clinical studies are also discussed in section II.B.5.b.ii of this
document.
b. Studies resolving the altered liver function issue. The
petitioner performed two 1-year chronic toxicity studies (rats and
monkeys) and the human clinical studies in an effort to resolve the
concern regarding liver function. These investigations are discussed in
sections II.B.5.b.i. and II.B.5.b.ii. of this document.
i. One-Year Chronic Toxicity Studies (Appendices 83 and 84). The
1-year chronic toxicity studies were performed in rats and in monkeys
in order to evaluate any general toxicological effects of SAIB in these
animals and to investigate whether there were effects on liver function
in rats and monkeys chronically-exposed to SAIB.
Rat Study (Appendix 83). Groups of male and female Charles River
rats (20 per sex per group) were fed SAIB in the diet at dose levels of
0, 0.5, 1.0, or 2.0 g/kg bw/d for 52 weeks. The control group was fed
the diet minus SAIB for the same duration. BSP clearance tests were
performed during weeks 23 and 48 on all control and high-dose rats
after an overnight fast. Ophthalmic examinations were performed at
weeks 0, 26, and 52 of the study. Selected hematology and clinical
chemistry tests were performed on 10 animals prior to dosing and on all
animals at weeks 27 and 53. Histopathological examinations were
performed on tissue from liver, kidneys, lungs, and all lesions from
all dose groups. Liver sections were also processed for electron
microscopy.
A small bw gain decrement (10.3 percent) was observed in the high-
dose (2.0 g/kg bw/d) SAIB-treated females. The mean final bw in the
high-dose females was also significantly decreased by 6.4 percent,
compared to controls. The decreased bw gain in the high-dose females
was mostly accounted for by decreased food intake (4-percent
reduction). BW gains in the SAIB-treated females at the mid and low
doses were not different from control females. The decreases in bw gain
that were sporadically seen in the SAIB-treated males in the short-term
studies were not observed in the males during this 1-year chronic
study. Because the bw gain decrement observed in the high-dose females
was small, and because it was not observed in either the low- or mid-
dose females or in treated males, and was partially accounted for by
decreased food intake in females, the agency concludes that this effect
is not toxicologically significant.
No differences were observed in BSP clearance between the SAIB-
treated rats and the control rats at 23 or 48 weeks. Other clinical
chemistry parameters measured in the SAIB-treated rats at week 53 were
comparable to values in control rats.
An increased incidence of high-dose female rats with hepatocellular
adenomas (2 out of 19) was observed in this study but was not seen in
the longer-term (2-year) rat carcinogenicity study on SAIB, indicating
that this effect was not treatment related (see section II.B.4 of this
document). Therefore, the agency concludes that there are no
indications of liver toxicity or other toxicologically significant
effects seen in rats chronically exposed to SAIB for 1 year. The NOEL
for this study is 2.0 g/kg bw/d, the highest dose tested (Refs. 5, 16,
and 25).
Monkey Study (Appendix 84). In this study, groups of Cynomolgus
monkeys (four per sex per group; young adults, age unknown) were
administered SAIB in corn oil by gavage at doses of 0, 0.50, 1.45, or
2.40 g/kg bw/d for 1 year. The control group was administered only corn
oil in a similar manner for the same duration. Ophthalmic,
hematological, and clinical chemistry examinations were performed at
pretest and at months 3, 6, 9, and 12 of the study. BSP clearance tests
were performed to assess liver function in all
[[Page 29956]]
animals at pretest and at months 3, 6, 9, and 12 of the study. Organ
weight data (absolute and relative) were collected on brain, thyroid/
parathyroid, heart, kidney, liver, testis, spleen, ovary, pituitary,
and adrenals for all monkeys after week 52 of the study. Macroscopic
and microscopic examinations were performed at sacrifice (week 52) on
representative tissue from a comprehensive selection of organs. Liver
sections from the monkeys in the control and high-dose group were
processed for electron microscopy.
The survival, bw, ophthalmoscopic, and hematological data showed no
findings that were toxicologically significant or SAIB-related. There
were some differences noted between the SAIB-treated and control
monkeys for some of the clinical chemistry parameters, but these were
sporadically expressed and thus were not toxicologically significant.
Data from the clinical chemistry parameters that assessed
hepatobiliary function did not reveal any effects that could be
attributed to the administration of SAIB. The percentages of BSP
excretion seen 30 minutes after BSP dye injection in the SAIB-treated
monkeys at 3, 6, and 12 months, were similar to those seen in controls
at comparable time intervals. There were no differences between SAIB-
treated monkeys and control monkeys with respect to SAP levels,
cholesterol, bile acids, bilirubin, and gamma glutamyl transpeptidase.
Organ weight data for SAIB-treated monkeys were comparable to control
monkeys except for some occasional differences in the combined weights
of the thyroid and parathyroid glands (absolute and relative) in the
low- and mid-dose male monkeys and in the absolute and relative ovary
weights in high-dose female monkeys. The liver weights (absolute or
relative weights) of the dosed monkeys were not different from the
liver weights in control monkeys. The agency concludes that none of
these changes are toxicologically significant.
Electron micrographs of liver tissue from the SAIB-treated monkeys
(high-dose group, four per sex) showed no difference from controls in
the quantity of smooth endoplasmic reticulum in their livers. Compared
to the controls, there were no ultrastructural changes in either the
mitochondria or their associated rough and smooth endoplasmic reticula
or any evidence of peroxisomal proliferation in the liver of the SAIB-
treated monkeys. Based upon these findings, the agency concludes that
there was no evidence of abnormalities in the livers of the SAIB-
treated monkeys compared to livers from control monkeys that would
indicate an SAIB-induced effect on liver function.
Based upon FDA's review of the data in this 1-year chronic study,
the agency concludes that SAIB does not affect the function or
ultrastructure of the liver in monkeys when orally administered at
doses up to 2.40 g/kg bw/d for 1 year. No other SAIB-related
histopathological lesions were observed in the SAIB-treated monkeys,
nor was there other evidence of adverse effects in the SAIB-gavaged
monkeys at any of the administered doses. Therefore, the agency has
determined that the NOEL for this study is 2.40 g/kg bw/d (Refs. 5 and
17).
ii. Human clinical studies (Appendices 97, 98, and 99). The
primary objective of the human clinical studies was to evaluate any
potential effects of SAIB on liver function in humans when administered
as a single daily dose for 14 days.
In a 14-day study (Appendix 97), SAIB was administered to 20 human
subjects (10 per sex) daily as a single dose of 0.01 g/kg bw/d. In a
second 14-day study (Appendix 98), groups of human subjects (4 per sex)
were administered daily a carbonated beverage containing SAIB at either
a dose of 0.007 g/kg bw or 0.20 g/kg bw. A third group (four per sex)
served as a control and were administered daily a carbonated beverage
without SAIB. In a third 14-day study (Appendix 99), groups of 13 human
male and 14 human female human subjects were administered daily orange
juice containing SAIB at a dose of 0.02 g/kg bw/d . In each of these
clinical studies, hematology and clinical chemistry parameters were
measured prior to the SAIB dosing on day 0, during the study on day 7,
and at the end of the study on day 14 or 18. BSP clearance tests were
performed prior to the SAIB dosing and postdosing on day 15.
None of these studies showed any SAIB-related abnormalities in any
of the hematology or clinical chemistry parameters measured in these
studies, including those clinical chemistry parameters that assessed
hepatobiliary function (i.e., SAP levels, alanine amino transferase,
aspartate amino transferase, lactate dehydrogenase, gamma glutamyl
transferase, bile acids, and total bilirubin). BSP retention in all of
the SAIB-treated human subjects was normal compared to pretest values
or control values.
Based upon the data in these studies, the agency concludes that
SAIB is not toxic in humans and does not induce liver toxicity at doses
up to 0.02 g/kg bw/day for 14 days. The 0.02 g/kg bw SAIB dose is
equivalent to exposures resulting from drinking 4 liters per day of a
beverage containing SAIB at its assumed maximum allowable use level of
300 milligrams/liter (mg/L) (Refs. 5, 26, 27, and 28).
c. Agency conclusions regarding altered liver function issue.
During the initial safety review of SAIB, FDA raised a concern that,
regardless of the tested dose or study duration, treatment-related
liver effects were consistently noted in SAIB-treated dogs. In response
to this concern, the petitioner provided a significant amount of
pharmacokinetics and metabolism data on SAIB in various species,
including humans. Based on these data, FDA finds that there appear to
be greater quantitative differences in the absorption and metabolism of
SAIB between dogs and humans than between the other tested species and
humans. To evaluate further the significance of the liver effects to
the overall safety of SAIB for human consumption, the agency carefully
considered the test results with monkeys, a nonhuman primate species
that is phylogenetically closest to humans, as well as liver function
data collected directly from human subjects in the three clinical
studies.
Unlike the liver effects seen in SAIB-treated dogs, there was no
evidence of liver effects in the specific liver function tests with
monkeys that received acute oral doses of SAIB as high as 5 g/kg bw
(Appendix 84). Data also demonstrate a lack of treatment-related liver
effects in monkeys that were exposed continuously to SAIB at dose
levels up to 2.4 g/kg bw/d over a 1-year treatment period. Importantly,
this dose level of 2.4 g/kg bw/d is nearly one thousand fold the
anticipated 90th percentile human exposure of SAIB in the daily diet.
FDA's review of the human clinical studies (Appendices 97, 98, and
99) further support the agency's conclusion regarding the significance
of the liver effects. In all three clinical studies, no SAIB-induced
effects on liver function were observed in either male or female
subjects. While the duration of the human studies was relatively short
(14 days), the highest dose used (0.02 g/kg bw/d) provided reasonable
assurance, in conjunction with the chronic monkey study data (Appendix
84), that the liver effects seen in SAIB-treated dogs will not occur in
humans that ingest SAIB. The highest dose tested in the human clinical
studies is equivalent to an exposure resulting from the drinking 4 L/d
of a beverage containing SAIB at its proposed maximum allowable use
level of 300 mg/L.
[[Page 29957]]
Based upon FDA's reviews of the nonhuman primate data and the
direct human data provided in the SAIB data base, the agency concludes
that the liver function effect seen in SAIB-treated dogs is not
determinative of the overall safety evaluation of SAIB for human
consumption. The agency further concludes that there is reasonable
certainty that the adverse liver effects seen in the SAIB-treated dogs
will not occur in humans that consume SAIB at the anticipated levels of
dietary intake.
C. Acceptable Daily Intake for SAIB
As discussed in section II.B.5.c of this document, FDA has relied
on the monkey and human data to resolve questions concerning the
altered liver function observed in SAIB-treated dogs. To support the
overall safety of SAIB for human consumption and to establish an ADI,
FDA has relied on data from rat studies of SAIB because the most
complete toxicological profile of SAIB was established in this rodent
species. The rat studies in the SAIB data base assess both the
potential carcinogenicity and the reproductive/developmental toxicity
of SAIB. In addition, because of their duration and size, the chronic
rat studies had greater sensitivity and thus, were more likely to
manifest treatment-related chronic effects. Furthermore, the available
absorption and metabolism data demonstrated substantial similarities,
both qualitative and quantitative, between rats and humans in the
metabolic handling of SAIB following oral ingestion.
Based on the 1- and 2-year rat studies, FDA determined that the
highest dose tested in both studies (2.0 g/kg bw/d) was the NOEL for
SAIB. Based on this NOEL and the use of a safety factor of 100, FDA
calculated an ADI of 0.02 g/kg bw/d or 1.20 g/p/d for SAIB (Ref. 5).
The EDI exposure for SAIB is 0.17 g/p/d (90th percentile, all ages)
which is 14 percent of the ADI calculated for the additive.
III. Conclusion
Based on all the SAIB data reviewed by the agency, FDA concludes
that there is a reasonable certainty that no harm will result from the
use of SAIB as an emulsion stabilizer for flavoring oils in
nonalcoholic beverages, and thus, SAIB is safe for its proposed use.
Therefore, the agency concludes that the food additive regulations
should be amended as set forth in this document.
In accordance with Sec. 171.1(h) (21 CFR 171.1(h)), the petition
and the documents that FDA considered and relied upon in reaching its
decision to approve the petition are available for inspection at the
Center for Food Safety and Applied Nutrition by appointment with the
information contact person listed above. As provided in Sec. 171.1(h),
the agency will delete from the documents any materials that are not
available for public disclosure before making the documents available
for inspection.
IV. Environmental Effects
The agency has determined under 21 CFR 25.32(k) that this action is
of a type that does not individually or cumulatively have a significant
effect on the human environment. Therefore, neither an environmental
assessment nor an environmental impact statement is required.
V. Paperwork Reduction Act of 1995
This final rule contains no collection of information. Therefore,
clearance by the Office of Management and Budget under the Paperwork
Reduction Act of 1995 is not required.
VI. References
The following references have been placed on display in the Dockets
Management Branch (address above) and may be seen by interested persons
between 9 a.m. and 4 p.m., Monday through Friday. Note: References with
an asterisk are not on display; they are available generally because
they are published articles or books.
1. Memorandum, from DiNovi, Division of Product Manufacture and
Use, to Anderson, Direct Additives Branch, FDA, July 31, 1991.
2. Memorandum from Taylor, Additives Evaluation Branch, to
McLaughlin, Direct Additives Branch, FDA, November 4, 1985.
3. Memorandum from Pellicore, Additives Evaluation Branch, to
Anderson, Direct Additives Branch, FDA, September 29, 1992.
4. Memorandum from Pellicore, Additives Evaluation Branch, to
Anderson, Novel Ingredients Branch, FDA, February 5, 1993.
5. Memorandum from Whiteside, Division of Health Effects
Evaluation, to Anderson, Division of Product Policy, FDA, August 27,
1998.
6. Memorandum from Donnely, Genetic Toxicity Branch, to Dunkel,
Genetic Toxicity Branch, FDA, September 23, 1985.
7. Memorandum from Prival, Additives Evaluation Branch #1, to
Whiteside, Additives Evaluations Branch #2, FDA, March 14, 1996.
8. Memorandum from Moreland, Genetic Toxicity Branch, FDA,
August 12, 1985.
9. Memorandum from Lavappa, Genetic Toxicity Branch, to Chief,
Genetic Toxicity Branch, FDA, September 9, 1985.
10. Memorandum from Bradlaw, Genetic Toxicity Branch, to Dunkel,
Genetic Toxicity Branch, FDA, May 24, 1985.
11. Memorandum from Bradlaw, Genetic Toxicity Branch, to Dunkel,
Genetic Toxicity Branch, FDA, August 15, 1985.
12. Memorandum from Bradlaw, Genetic Toxicity Branch, to Lin,
Additives Evaluation Branch, FDA, September 6, 1989.
13. Memorandum from Welsh, Additives Evaluation Branch #2, to
Whiteside, Additives Evaluations Branch #2, FDA, August 28, 1995.
14. Memorandum from Whiteside, Division of Health Effects
Evaluation, to Lorentzen, Cancer Assessment Committee, FDA, March
18, 1997.
15. Memorandum of Conference, Cancer Assessment Committee
Meeting, FDA, October 28, 1996.
16. Memorandum from Raffaele, Additives Evaluations Branch #2,
to Whiteside, Additives Evaluations Branch #2, FDA, June 23, 1994.
17. Memorandum from Whiteside, Additives Evaluation Branch #2,
to Anderson, Direct Additives Branch, FDA, March 23, 1994.
18. Memorandum from Whiteside, Additives Evaluation Branch #2,
to Anderson, Direct Additives Branch, FDA, August 20, 1993.
*19. Cornelius, C. E., ``Liver Function,'' Clinical
Biochemistry of Domestic Animals, C. E. Cornelius and J. J. Kaneko,
eds. Academic Press, pp. 251-264, 1963.
*20. Cornelius, C. E., et al., ``An assessment of hepatic
function in rhesus and squirrel monkeys,'' Veterinary Medicine/Small
Animal Clinicals, 78: 1885-1888, 1983.
*21. Cornelius, C. E., ``Liver Function,'' Clinical Biochemistry
of Domestic Animals, 4th ed. Jiro J. Kaneko, Ed., Academic Press,
Inc., pp. 375-379, 391-397,1989.
*22. Poutsiaka, et al., ``Simultaneous Determination in Dogs of
Liver and Kidney Functions with Bromosulfalein and
Phenolsulfonephthalein,'' Toxicology and Applied Pharmacology, 4:55,
1962.
*23. Krasavage, et al., ``Indocyanine Green Testing,''
Proceedings Society for Experimental Biology of Medicine, 119: 215,
1965.
*24. Bonasch, H. and C. E. Cornelius, ``Indocyanine Green: A
Liver Function Test for the Dog,'' American Journal of Veterinary
Research, 25: 254-59, 1964.
25. Memorandum from Alam, Pathology Branch, to Anderson, Novel
Ingredients Branch, FDA, July 10, 1997.
26. Memorandum from Hotta, Clinical Nutrition Branch, to
Blendermann, Division of Nutrition, FDA, December 31, 1986.
27. Memorandum from Calvert, Clinical Nutrition Branch, to
Anderson, Novel Ingredients Branch, FDA, January 21, 1992.
28. Memorandum from Calvert, Clinical Nutrition Branch, to
Anderson, Novel Ingredients Branch, FDA, September 2, 1993.
VI. Objections
Any person who will be adversely affected by this regulation may at
any time on or before July 6, 1999, file with the Dockets Management
Branch (address above) written objections thereto. Each objection shall
be separately numbered, and each numbered objection shall specify with
particularity the provisions of the regulation to which objection is
made and the grounds for the objection. Each numbered objection on
which a hearing is requested shall specifically so state.
[[Page 29958]]
Failure to request a hearing for any particular objection shall
constitute a waiver of the right to a hearing on that objection. Each
numbered objection for which a hearing is requested shall include a
detailed description and analysis of the specific factual information
intended to be presented in support of the objection in the event that
a hearing is held. Failure to include such a description and analysis
for any particular objection shall constitute a waiver of the right to
a hearing on the objection. Three copies of all documents shall be
submitted and shall be identified with the docket number found in
brackets in the heading of this document. Any objections received in
response to the regulation may be seen in the Dockets Management Branch
between 9 a.m. and 4 p.m., Monday through Friday.
List of Subjects in 21 CFR Part 172
Food additives, Incorporation by reference, Reporting and
recordkeeping requirements.
Therefore, under the Federal Food, Drug, and Cosmetic Act and under
authority delegated to the Commissioner of Food and Drugs, 21 CFR part
172 is amended as follows:
PART 172--FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR
HUMAN CONSUMPTION
1. The authority citation for 21 CFR part 172 continues to read as
follows:
Authority: 21 U.S.C. 321, 341, 342, 348, 371, 379e.
2. Section 172.833 is added to subpart I to read as follows:
Sec. 172.833 Sucrose acetate isobutyrate (SAIB).
Sucrose acetate isobutyrate may be safely used in foods in
accordance with the following prescribed conditions:
(a) Sucrose acetate isobutyrate (CAS Reg. No. 27216-37-1), or SAIB,
is the chemical alpha-D-glucopyranoside, O-acetyl-tris-O-(2-methyl-1-
oxopropyl)-beta-D-fructofuranosyl, acetate tris(2-methyl propanoate).
(b) SAIB, a pale, straw-colored liquid, meets the following
specifications:
(1) Assay: Not less than 98.8 percent and not more than 101.9
percent, based on the following formula:
Assay = ((SV 0.10586) 56.1) x 100
Where SV = Saponification value
(2) Saponification value: 524-540 determined using 1 gram of sample
by the ``Guide to Specifications for General Notices, General
Analytical Techniques, Identification Tests, Test Solutions, and Other
Reference Materials,'' in the ``Compendium of Food Additive
Specifications, Addendum 4, Food and Agriculture Organization of the
United Nations (FAO), Food and Nutrition Paper 5, Revision 2'' (1991),
pp. 203 and 204, which is incorporated by reference, in accordance with
5 U.S.C. 552(a) and 1 CFR part 51. Copies are available from the Office
of Premarket Approval, Center for Food Safety and Applied Nutrition
(HFS-200), Food and Drug Administration, 200 C St. SW., Washington, DC
20204, or may be examined at the Center for Food Safety and Applied
Nutrition's Library, 200 C St. SW., rm. 3321, Washington, DC, or at the
Office of the Federal Register, 800 North Capitol St. NW., suite 700,
Washington, DC.
(3) Acid value: Not to exceed 0.20 determined using 50 grams of
sample by the ``Guide to Specifications for General Notices, General
Analytical Techniques, Identification Tests, Test Solutions, and Other
Reference Materials,'' in the ``Compendium of Food Additive
Specifications, Addendum 4, FAO Food and Nutrition Paper 5, Revision
2,'' p. 189 (1991), which is incorporated by reference; see paragraph
(b)(2) of this section for availability of the incorporation by
reference.
(4) Lead: Not to exceed 1.0 milligrams/kilogram determined by the
``Atomic Absorption Spectrophotometric Graphite Furnace Method, Method
I,'' in the ``Food Chemicals Codex,'' 4th ed. (1996), pp. 763 and 764,
with an attached modification to the sample digestion section in
Appendix III.B (July 1996), which is incorporated by reference. Copies
are available from the National Academy Press, 2101 Constitution Ave.
NW., Box 285, Washington, DC 20055 (Internet ``http://www.nap.edu''),
or may be examined at the Center for Food Safety and Applied
Nutrition's Library, 200 C St. SW., rm. 3321, Washington, DC, or at the
Office of the Federal Register, 800 North Capitol St. NW., suite 700,
Washington, DC.
(5) Triacetin: Not to exceed 0.10 percent determined by gas
chromatography as described in the ``Guide to Specifications for
General Notices, General Analytical Techniques, Identification Tests,
Test Solutions, and Other Reference Materials,'' in the ``Compendium of
Food Additive Specifications, Addendum 4, FAO Food and Nutrition Paper
5, Revision 2'' (1991), pp. 13-26, which is incorporated by reference;
see paragraph (b)(2) of this section for availability of the
incorporation by reference.
(c) The food additive is used as a stabilizer (as defined in
Sec. 170.3(o)(8) of this chapter) of emulsions of flavoring oils in
nonalcoholic beverages.
(d) The total SAIB content of a beverage containing the additive
does not exceed 300 milligrams/kilogram of the finished beverage.
Dated: May 27, 1999.
William K. Hubbard,
Associate Commissioner for Policy Coordination.
[FR Doc. 99-14147 Filed 6-3-99; 8:45 am]
BILLING CODE 4160-01-F
