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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Justification of read-across: Both chemicals are of comparable structures with minor deviations and can be characterized as an ester of sorbitan and a fatty acid. Justification of reliability of 2: Comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
analytical purity of test substance not reported
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
- Name of test material (as cited in study report): Sorbitan, monooctadecanoate (SMO)
- Physical state: yellow crystalline pellet
- Analytical purity: no data
- Stability under test conditions: verified
- Storage condition of test material: sealed and kept at room temperature

Method

Target gene:
his operon
Species / strainopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
SD rat liver S9 mix
Species / strain:
E. coli WP2 uvr A
Additional strain characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
SD rat liver S9 mix
Test concentrations with justification for top dose:
ge-finder: 0, 50, 150, 500, 1500, 5000 µg/plate
Main study: 0, 313, 625, 1250, 2500, 5000 µg/plate
Vehicle:
- Vehicle(s)/solvent(s) used: DMSO
Controls
Negative controls:
not specified
Solvent controls:
yes
True negative controls:
not specified
Positive control substance:
9-aminoacridine
sodium azide
other: (2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide), 2-Aminoanthracene
Details on test system and conditions:
METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 minutes
- Exposure duration: 48 hours

NUMBER OF REPLICATIONS: 3
two independent experiments were performed, each in triplicate

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth
Statistics:
If the average number of colonies on plates containing the test substance increased more than twice the negative control, the test is considered positive.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to precipitating concentrations
Vehicle controls valid:
yes
Negative controls valid:
not specified
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
no, but tested up to precipitating concentrations
Vehicle controls valid:
yes
Negative controls valid:
not specified
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: at concentration of 625 µg/plate (without S9) and at 1250 µg/plate (with S9) and higher concentrations in both experiments.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
Cytotoxicity was observed at precipitating concentrations

Any other information on results incl. tables

The analogue approach using sorbitan stearate as source chemical is justified:

Both chemicals are of comparable structures with minor deviations and can be characterized as an ester of sorbitan and a fatty acid. Compared to the source chemical, the target chemical has a shorter alkyl chains that affect its physicochemical properties. But based on the kinetic / metabolic investigations on both chemicals, the length of the alkyl chain is not considered to have significant impact on the metabolic pathway or toxicological mode of action. Oral gavage studies in rats administered C14 labeled sorbitan stearate in oil solutions have demonstrated that about 90% of the substance was absorbed and hydrolyzed to stearic acid and sorbitan. The metabolic fate of sorbitan caprylate was investigated using a lipase assay. The hydrolysis mediated by porcine pancreas lipase was quantitatively determined. The target chemical sorbitan caprylate is proved to be hydrolyzed and caprylic acid was formed . These findings suggest that metabolism of the sorbitan occur initially via enzymatic hydrolysis, leading to sorbitan and the corresponding natural acids.

Based on the above mentioned information, it is reasonable to consider that these two substances are comparable in their metabolic fate and thereby toxicological profiles. Hence, the source chemical is considered as “suitable with interpretation” analog.

According to the available toxicity studies, the findings are also comparable for target and source chemicals:

·        The findings in acute toxicity studies are comparable. Both chemicals are of no acute toxicity.

·        The findings in subacute dose toxicity studies are comparable. No treatment effects were observed in 28-day repeated toxicity studies in Wistar rats. The same NOEL of 1000 mg/kg bw/d was derived for both chemicals.

·        The findings in genetic toxicity are comparable. Both chemicals did not induce gene mutations in Ames tests, but induced structural chromosomal aberrations in cell lines of Chinese Hamster.

·        The findings in reproduction / developmental toxicity studies are comparable.

Table 1: Summary of Ames Test result (experiment 1)

Maximum number of revertants

solvent control

positive control

treatment

(at dose level [µg/plate])

Strain

With S9

Without S9

With S9

Without S9

With S9

Without S9

TA 100

161

139

818

512

166 (313)

135 (1250)

TA 1535

13

13

378

641

12 (1250)

13 (625)

WP2 uvrA

25

26

951

113

35 (313 and 5000)

27 (625)

TA 98

39

23

374

457

40 (625)

26 (1250)

TA 1537

18

7

152

321

19 (1250)

10 (1250)

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

It can be concluded that under the experimental conditions reported, the test item did not induce gene mutations in the genome of the strains used.
Executive summary:

The genetic toxicity of sorbitan caprylate was assessed based on the analogue approach using sorbitan monostearate as a read-across supporting substance.

The gene mutation potential of Sorbitan monostearate was investigated in the plate using the Salmonella typhimurium strains TA 1535, TA 1537, TA 98, and TA 100, and the Escherichia coli strain WP2 uvrA.

The assay was performed iboth with and without liver microsomal activation. The test item was tested at the following concentrations:

313; 625; 1250; 2500; and 5000 µg/plate.

No substantial increase in revertant colony numbers of any of the five tester strains was observed following treatment with sorbitan monostearate at any dose level, neither in the presence nor absence of metabolic activation (S9 mix).

It can be concluded that under the experimental conditions reported, the test item did not induce gene mutations in the genome of the strains used.