Hexamethylene diisocyanate, oligomerisation product, blocked with 2-butanone oxime

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well conducted guideline, GLP with some deviations

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

Only 4 strains tested instead of 5, no data available on analytical investigation of the compound, the signature who approved the protocol was undated.

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Desmodur BL 3175

IUPAC Name:

Desmodur BL 3175

Details on test material:

- Name of test material (as cited in study report): Desmodur BL 3175
- Physical state: viscous clear liquid
- Lot/batch No.: 0037
- Expiration date of the lot/batch:
- Stability under test conditions: A stability test did not reveal any significant change of the concentration of the active ingredient in the solvent over
the test period
- Storage condition of test material: refrigerator
- Other: the batch used was checked for identity prior to study initiation and approved for use during the test period.

Method

Target gene:

Not applicable

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Details on mammalian cell type (if applicable):

not applicable

Metabolic activation:

with and without

Metabolic activation system:

liver homogenate derived from Aroclor1254 induced rats (S9 mix)

Test concentrations with justification for top dose:

Doses per plate used for the first assay: 0, 8, 40, 200, 1000 and 5000 µg/plate.
Doses per plate used for the repeat assay: 0, 8, 40, 200, 1000 and 3000 µg/plate.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used:
The solvent employed for the DESMODUR BL 3175 is acetone.The solvent used for the positive control is DMSO.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Sodium azide, Nitrofurantoin, 4-nitro-1,2-phenylene diamine, 2-aminoanthracene,

Remarks:

No remarks

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

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

NUMBER OF REPLICATIONS: 4 tubes were plated by strain for each concentration and control. 3 tests have been performed. In the first assay, tubes
were plated immediately after addition of the last component whereas in the 2 repeat tests, all tubes were preincubated at 37°C for 30 min before
plating. Because of cytotoxicity in the first repeat dose, this assay has not been interpretable.

DETERMINATION OF CYTOTOXICITY

The total bacteria counts consistently produced results in the range of the negative controls, or differed only insignificantly.
No growth inhibition was observed.
Higher doses revealed a weak, strain-specific bacteriotoxic effect. Nevertheless, doses up to 5000 µg/plate could still be used for assessment.
In the first preincubation test, bacteriotoxic effects most likely due to the solvent acetone were observed for all plates including the solvent control
plates. The result of this first preincubation test was not interpretable. Therefore a second preincubation test was performed in which only 0.06 ml of acetone was used as a solvent. No solvent-induced bacteriotoxic effects were observed in this repeat experiment.

The substance precipitated at a dose of 5000 µg/plate. As a result the corresponding plates could not be evaluated.

Evaluation criteria:

A test is defined as being positive if a reproductible and dose-related increase of mutany colony numbers becomes apparent for at least one strain.
For TA 1535, TA 100 and TA 98 mutant colony numbers should increase by a factor of two or more over the negative control numbers, while at least a three-fold increase should be apparent for TA 1537. Otherwise, the result is judged as negative.
However, these guidelines may be overruled bu good scientific judgement.

Statistics:

No data

Results and discussion

Test results

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

None of the four test strains showed a dose-related and biologically relevant increase of revertant colony numbers after exposure to the test
substance over negative control levels. This applied to the tests with and without S9 mix and was confirmed by the results of the repeat test.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

Table 7.6.1/1: Number of revertants per plate (mean of quadruplicates) in the absence of metabolic activation (First test)

Test substance concentration (µg/plate)	TA 1535	TA 100	TA 1537	TA 98
	Mean	Mean	Mean	Mean
0	13	75	8	22
8	12	79	7	28
40	17	86	8	23
200	13	87	8	22
1000	14	72	7	21
5000	10	72	9	17
Na-azide	636
NF		271
4-NPDA			42	92

Table 7.6.1/2: Number of revertants per plate (mean of triplicates) in the absence of metabolic activation (Second test)

Test substance concentration (µg/plate)	TA 1535	TA 100	TA 1537	TA 98
	Mean	Mean	Mean	Mean
0	16	100	11	26
8	14	96	11	29
40	17	97	13	30
200	16	104	10	27
1000	15	105	8	26
5000	14	110	8	19
Na-azide	522
NF		499
4-NPDA			51	85

 

Table 7.6.1/3 Number of revertants per plate (mean of triplicates) in the presence of metabolic activation (First test)

Test substance concentration (µg/plate)	TA 1535	TA 100	TA 1537	TA 98
	Mean	Mean	Mean	Mean
0	16	119	10	45
8	13	108	8	43
40	13	108	8	40
200	13	108	11	26
1000	13	114	5	31
5000	15	105	6	22
2-AA	152	917	205	693

 

Table 7.6.1/4 Number of revertants per plate (mean of triplicates) in the presence of metabolic activation (Second test)

Test substance concentration (µg/plate)	TA 1535	TA 100	TA 1537	TA 98
	Mean	Mean	Mean	Mean
0	18	147	11	32
8	15	138	14	42
40	18	152	14	45
200	18	160	16	40
1000	14	154	12	41
5000	15	125	10	35
2-AA	180	1317	302	1113

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative with and without metabolic activation

Under the test conditions, DESMODUR BL 3175 was not mutagenic in bacteria.

Executive summary:

In a reverse gene mutation assay in bacteria performed according to OECD guideline 471 and in compliance with GLP, DESMODUR BL 3175 was tested in S. typhimurium TA 1535, TA 1537, TA 100, TA 98.

Two independent mutation tests were performed in the presence and the absence metabolic activation. The first test was a standard plate incorporation assay conducted at 0, 8, 40, 200, 1000 and 5000 µg/plate for DESMODUR BL 3175. The second assay involved a 30-minute pre-incubation at 37°C using 0, 8, 40, 200, 1000 and 3000 µg/plate for DESMODUR BL3175.

The substance precipitated at a dose of 5000 µg/plate.

The positive controls induced the appropriate responses in the corresponding strains.

Increase in the revertants was not observed in any tested strains following exposure to DESMODUR BL3175 at any concentrations in the absence and the presence of S9 -mix activation system.

Under the test conditions, DESMODUR BL3175 is not mutagenic in bacteria in the absence and the presence of activation sytem.

This study is considered as acceptable and satisfies the requirement for the bacterial reverse gene mutation endpoint.