Sodium 4-propoxycarbonylphenoxide

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In the absence of data on genetic toxicity on target substance sodium propyl 4-hydroxybenzoate an analogue read-across approach was conducted on source substances propyl 4-hydroxybenzoate for following endponits:

- Ames test (OECD 471): negative with and without metabolic activation in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

- Gene mutation in mammalian cells (OECD 476): negative in Chinese hamster lung fibroblasts (V79) cells with and without metabolic activation.

- In vitro Mammalian Cell Micronucleus Test (OECD 487): non clastogenic and/or non aneugenic with and without metabolic activation

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 July 2018 TO 24 October 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

see read-acorss justification attached in chapter 13.refer to analogue justification provided in IUCLID section 13

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

Adopted on 21st July 1997

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and batch No.of test material: Clariant India Limited and BP16102712
- Expiration date of the batch:27.10.2019
- Purity test date:99,7%

STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient (21 to 29°C)
- Solubility of the test substance in the solvent/vehicle:Dimethyl sulphoxide

OTHER SPECIFICS:
- CAS No. :94-13-3
- Physical Appearance (with colour) : White powder

Target gene:

Histidine Locus

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Metabolic activation:

with and without

Metabolic activation system:

1 mL of S9 homogenate was mixed with 9 mL co factor

Test concentrations with justification for top dose:

Based on the results of solubility, precipition and initial cytotoxicity test, concentrations of 0.01, 0.03, 0.10, 0.32 and 1 mg/plate were selected for testing in the mutation test by plate incorporation and pre incubation method.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle:The test item was soluble in dimethyl sulphoxide at 50 mg/mL

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

mitomycin C

other: 2-aminoantracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: In agar (plate incorporation); preincubation;

DURATION
- Preincubation period: 30 minutes
- Exposure duration:The plates were incubated at 37±1ºC for 71 hours and 15 minutes for initial cytoyoxicity
Plate incorporation method - Plates were incubated at 37±1°C for 48 hours and 5 minutes.
Preincubation method - Plates were incubated at 37±1°C for 64 hours and 30 minutes.

NUMBER OF REPLICATIONS: Triplicates

Rationale for test conditions:

Not applicable

Evaluation criteria:

The test will be judged positive if the increase in mean revertants at the peak of the dose response is equal to or greater than 2 times the mean vehicle control value in Salmonella typhimurium strains TA98, TA100 and TA102 or equal to or greater than 3 times the mean vehicle control value in tester strains TA1535 and TA1537

Statistics:

Not applicable

Key result

Species / strain:

S. typhimurium TA 1535

Remarks:

TA1537,TA102,TA100,TA98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Water solubility: Insoluble in water
- Precipitation:The test item resulted in minimal precipitation at 5 mg/plate and no precipitation at and up to 4 mg/plate tested concentration


HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Vehicle historical control data:
Plate incorporation method:
TA 98 TA100 TA1535 TA1537 TA102 (With S9)
Mean 20.6 101.8 22.2 8.2 260.3
SD 1.6 1.7 1.6 1.1 5.2
Min 18 98 19 6 251
Max 25 106 26 13 272

TA 98 TA100 TA1535 TA1537 TA102 (Without S9)
Mean 20.9 101.7 22.2 8.6 261.8
SD 1.5 2.0 1.8 1.1 5.2
Min 19 94 18 7 254
Max 26 105 27 13 274

Pre incubation method:
TA 98 TA100 TA1535 TA1537 TA102 (With S9)
Mean 20.6 102.3 22.1 8.4 262.3
SD 1.5 1.9 2.0 1.0 4.6
Min 19 99 19 7 256
Max 25 108 28 11 275

TA 98 TA100 TA1535 TA1537 TA102 (Without S9)
Mean 20.8 101.8 22.4 8.4 263.8
SD 1.6 2.0 2.0 1.1 5.5
Min 18 99 20 7 251
Max 24 106 28 11 275

- Positive historical control data:

Plate incorporation method:

TA 98 TA100 TA1535 TA1537 TA102 (With S9)
Mean 412.0 385.5 143.2 118.2 606.2
SD 21.7 20.9 9.6 8.7 27.6
Min 280 306 117 100 510
Max 440 419 292 149 670

TA 98 TA100 TA1535 TA1537 TA102 (Without S9)
Mean 399.7 378.3 145.0 120.2 613.48
SD 36.2 23.9 12.6 8.5 22.6
Min 310 311 112 103 589
Max 428 446 190 158 694

Pre incubation method:
TA 98 TA100 TA1535 TA1537 TA102 (With S9)
Mean 410.1 386.0 144.2 117.1 606.5
SD 18.2 22.0 11.3 6.5 26.7
Min 290 298 103 102 508
Max 428 425 187 128 670

TA 98 TA100 TA1535 TA1537 TA102 (Without S9)
Mean 404.0 379.1 146.5 118.7 616.0
SD 29.0 23.7 14.5 5.5 25.9
Min 314 317 110 105 590
Max 428 450 200 134 699

Historical Data

Time Period: 2009 to 2017

Total No. of studies: 50 studies

Plate Incorporation Method

Metabolic Activation		With Metabolic Activation						Without Metabolic Activation
Tester strain		Salmonella typhimurium						Salmonella typhimurium
		TA 98	TA 100	TA 1535	TA 1537	TA 102		TA 98	TA 100	TA 1535	TA 1537	TA 102
Vehicle Control (DMSO)	Mean	20.6	101.8	22.2	8.2	260.3		20.9	101.7	22.2	8.6	261.8
	±SD	1.6	1.7	1.6	1.1	5.2		1.5	2.0	1.8	1.1	5.2
	Min	18	98	19	6	251		19	94	18	7	254
	Max	25	106	26	13	272		26	105	27	13	274
Positive Control	Mean	412.0	385.5	143.2	118.2	606.2		399.7	378.3	145.0	120.2	613.4
	±SD	21.7	20.9	9.6	8.7	27.6		36.2	23.9	12.6	8.5	22.6
	Min	280	306	117	100	510		310	311	112	103	589
	Max	440	419	292	149	670		428	446	190	158	694
Preincubation Method
Metabolic Activation		With Metabolic Activation						Without Metabolic Activation
Tester strain		Salmonella typhimurium						Salmonella typhimurium
		TA 98	TA 100	TA 1535	TA 1537	TA 102		TA 98	TA 100	TA 1535	TA 1537	TA 102
Vehicle Control (DMSO)	Mean	20.6	102.3	22.1	8.4	262.3		20.8	101.8	22.4	8.4	263.8
	±SD	1.5	1.9	2.0	1.0	4.6		1.6	2.0	2.0	1.1	5.5
	Min	19	99	19	7	256		18	99	20	7	251
	Max	25	108	28	11	275		24	106	28	11	275
Positive Control	Mean	410.1	386.0	144.2	117.1	606.5		404.0	379.1	146.5	118.7	616.0
	±SD	18.2	22.0	11.3	6.5	26.7		29.0	23.7	14.5	5.5	25.9
	Min	290	298	103	102	508		314	317	110	105	590
	Max	428	425	187	128	670		428	450	200	134	699

Min: Minimum no. of colonies, Max: Maximum no. of colonies SD: Standard deviation           

Conclusions:

The test item, Propyl 4-hydroxybenzoate was evaluated for mutagenicity in Bacterial Reverse Mutation Test using Salmonella typhimurium TA98, TA100, TA102, TA1535 and TA1537 as per the OECD guideline for testing of chemicals No. 471. Based on initial cytotoxicity test the test item was tested at concentrations of 0.01, 0.03, 0.10, 0.32 and 1 mg/plate for mutagenecity in plate incorporation and preincubation method.
In both tests Propyl 4-hydroxybenzoate resulted in no appreciable increase in the number of revertant colonies in all five tester strains and in all tested concenrtrations over the vehicle control,while the positive controls tested simultaneously, resulted in 2.2 to 18.8 fold increasein the number of revertant colonies/plate under identical conditions. Based on the results obtained from the study, it is concluded that the test item, Propyl 4-hydroxybenzoate, is “non-mutagenic” in the Bacterial Reverse Mutation Test up to the highest tested concentration of 1 mg/plate under the test conditions.

Executive summary:

The test item was evaluated for mutagenicity in Bacterial Reverse Mutation Test using Salmonella typhimurium TA98, TA100, TA102, TA1535 and TA1537 according to OECD guideline 471 “Bacterial Reverse Mutation Test”. The test item was found to be soluble in dimethyl sulphoxide at a concentration of 50 mg/mL. The test item resulted in minimal precipitation at 5 mg/plate. Based on these results the highest concentration selected for initial cytotoxicity test was 5 mg/plate. Salmonella typhimurium TA100 tester strain was exposed to vehicle control, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4 and 5 mg/plate in the presence and absence of metabolic activation. This treatment resulted in cytotoxicity and those concentrations are graded as 0 (Absent lawn) for 5 mg/plate, 1+ (extremely reduced lawn) for 3 and 4 mg/plate, 2+(moderately reduced lawn) for 2 mg/plate and 3 + (Slightly reduced lawn) for 1 mg/platewhen compared to vehicle control. On the basis of cytotoxicity results, solubility and precipitation 1 mg/plate was considered as the highest test concentration for mutation assay. In mutation assay the test item was tested at the concentrations of 0.01, 0.03, 0.10, 0.32 and 1mg/plate. Two independent trials (trial 1 and 2) were conducted by plate incorporation method and pre incubation method in the presence and absence of metabolic activation system. Vehicle control (dimethyl sulphoxide) and appropriate positive controls (2-nitrofluorene, sodium azide and 9-Aminoacridine, Mitomycin C for trials “without metabolic activation” and 2-Aminoanthracene for trials “with metabolic activation”) were tested simultaneously. Based on the experimental results obtained, the mean numbers of revertant colonies at the tested concentrations were comparable to those of the vehicle control, in both the trials, in the presence and absence of metabolic activation. There was no appreciable increase in number of revertant colonies at any of the tested concentrations in both the trials. The number of revertant colonies in the positive controls resulted in 2.3 to 18.8 fold increase under identical conditions. Based on the results obtained from the study, it is concluded that the test item, Propyl 4-hydroxybenzoate, is “non-mutagenic” in the Bacterial Reverse Mutation Test up to the highest tested concentration of 1 mg/plate under the test conditions.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-02-16 to 2012-06-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Deviations:

no

Principles of method if other than guideline:

first experiment 4 hours treatment with and without metabolic activation
second experiment 24 hours treatment without metabolic activation, 4 hours treatment with metabolic activation

GLP compliance:

yes (incl. QA statement)

Type of assay:

other: in vitro mammalian cell gene mutation test using the Hprt and xprt genes (migrated information)

Target gene:

HPRT

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media: MEM
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: yes
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

Phenobarbital/Beta-Naphtoflavone induced Rat liver S9

Test concentrations with justification for top dose:

Experiment I / without metabolic activation / 4 hours treatment:
7.0, 14.0, 28.0, 56.0, 93.0, 112.0 µg/mL

Experiment I / with metabolic activation / 4 hours treatment:
28.0, 56.0, 112.0, 224.0, 336.0, 448.0 µg/mL

Experiment II / without metabolic activation / 24 hours treatement:
14.0, 28.0, 56.0, 112.0, 168.0, 224.0 µg/mL

Experiment II / with metabolic activation / 4 hours treatment:
28.0, 56.0, 112.0, 224.0, 336.0, 448.0 µg/mL

In experiment I with and without metabolic activation and in experiment II with metabolic activation the cultures at the maximum concentration were not continued due to exceed-ingly severe cytotoxicity. In the second experiment without metabolic activation the cultures at the two highest concentrations were not continued for the same reason.

Vehicle / solvent:

DMSO

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

7,12-dimethylbenzanthracene

ethylmethanesulphonate

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium


DURATION
- Exposure duration: Experiment I: 4 hours with and without metabolic activation, Experiment II: 24 hours without metabolic activation, 4 hours with metabolic activation
- Expression time (cells in growth medium): 72 hours
- Selection time (if incubation with a selection agent): 10 days

SELECTION AGENT (mutation assays): 6-Thioguanine


NUMBER OF REPLICATIONS: 2


NUMBER OF CELLS EVALUATED: >1,5x10exp. 6


DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency

Evaluation criteria:

A test item producing neither a concentration-related increase of the mutant frequency nor a reproducible positive response at any of the test points is considered to be non-mutagenic in this system.
A mutagenic response is described as follows:
The test item is classified as mutagenic if it induces reproducibly with one of the concentrations a mutation frequency that is three times higher than the spontaneous mutation frequency in the experiment.
The test item is classified as mutagenic if there is a reproducible concentration-related increase of the mutation frequency. Such evaluation may be considered also in the case that a threefold increase of the mutant frequency is not observed.
In a case by case evaluation this decision depends on the level of the corresponding solvent control data.

Statistics:

A linear regression (least squares) was performed to assess a possible dose dependent increase of mutant frequencies.The number of mutant colonies obtained for the groups treated with the test item was compared to the solvent control groups. A trend is judged as significant whenever the p-value (probability value) is below 0.05. However, both, biological relevance and statistical significance were considered together.

Key result

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: Not effected (pH 7.35 measured in the solvent control versus pH 7.34 measured at 1800 µg test item/mL
- Effects of osmolality: Not increased (383 in the solvent control versus 362 measured at 1800 µg test item/mL
- Evaporation from medium: Not examined
- Water solubility: --
- Precipitation: In the main experiments I and II no precipitation occurred.

- Other confounding effects: None


RANGE-FINDING/SCREENING STUDIES:
In the range finding pre-experiment test item concentrations between 14.1 and 1800 µg/mL (≈ 10 mM) were used to evaluate toxicity in the presence (4 hours treatment) and absence (4 hours and 24 hours treatment) of metabolic activation.
Relevant cytotoxic effects indicated by a relative suspension growth below 50% were noted at 112.5 µg/mL and above without metabolic activation following 4 hours treatment. In the presence of metabolic activation cytotoxic effects were observed at 450 µg/mL and above. After 24 hours treatment the cell growth was completely inhibited at 225 µg/mL and above.
The test medium was checked for precipitation or phase separation at the end of each treat-ment period prior to removal to the test item. Precipitation occurred at 900 µg/mL in the pres-ence and absence of metabolic activation following 4 and 24 hours treatment.
Based on the results of the pre-experiment, the individual concentrations of the main experiments were selected. The individual concentrations were generally spaced by a factor of 2. Narrower spacing was used at high concentrations to cover the cytotoxic range more closely.


COMPARISON WITH HISTORICAL CONTROL DATA: Complies


ADDITIONAL INFORMATION ON CYTOTOXICITY:
The recommended cytotoxic range of approximately 10-20% relative cloning efficiency I or relative cell density was covered with and without metabolic activation.

Summary Table

			relative	relative	relative	mutant		relative	relative	relative	mutant
	conc.	S9	cloning	cell	cloning	colonies/	induction	cloning	cell	cloning	colonies/	induction
	µg/mL	mix	efficiency I	density	efficiency II	10^6cells	factor	efficiency I	density	efficiency II	10^6cells	factor
			%	%	%			%	%	%
Column	1	2	3	4	5	6	7	8	9	10	11	12
Experiment I / 4 h treatment			culture I					culture II
Solvent control with DMSO		-	100.0	100.0	100.0	10.1	1.0	100.0	100.0	100.0	20.7	1.0
Positive control (EMS)	150.0	-	99.2	90.3	80.1	145.3	14.4	95.1	101.2	94.4	179.5	8.7
Test item	7.0	-	108.9	107.0	106.0	9.5	0.9	98.8	87.3	107.9	24.0	1.2
Test item	14.0	-	100.2	94.0	113.4	11.5	1.1	102.5	86.5	120.5	6.2	0.3
Test item	28.0	-	101.7	108.1	96.6	27.3	2.7	97.5	83.4	114.1	10.5	0.5
Test item	56.0	-	77.9	82.9	113.9	6.3	0.6	74.0	71.6	106.8	2.5	0.1
Test item	93.0	-	18.1	26.7	116.6	6.0	0.6	20.4	22.3	101.8	2.2	0.1
Test item	112.0	-	0.0	culture was not continued^#				0.0	culture was not continued^#
Solvent control with DMSO		+	100.0	100.0	100.0	14.0	1.0	100.0	100.0	100.0	11.8	1.0
Positive control (DMBA)	1.1	+	24.1	93.3	87.7	1105.5	79.2	25.7	74.5	85.4	751.9	63.6
Test item	28.0	+	82.5	133.1	90.6	12.4	0.9	89.5	118.4	107.2	9.3	0.8
Test item	56.0	+	95.2	125.9	98.5	14.2	1.0	100.8	103.9	106.9	11.2	0.9
Test item	112.0	+	86.9	130.6	95.8	13.2	0.9	94.4	103.4	94.8	7.3	0.6
Test item	224.0	+	79.3	118.9	100.8	4.9	0.4	97.1	90.8	93.4	4.2	0.4
Test item	336.0	+	14.3	117.8	95.7	7.8	0.6	13.0	95.1	100.7	6.8	0.6
Test item	448.0	+	0.2	culture was not continued^#				0.3	culture was not continued^#
Experiment II / 24 h treatment			culture I					culture II
Solvent control with DMSO		-	100.0	100.0	100.0	15.8	1.0	100.0	100.0	100.0	9.5	1.0
Positive control (EMS)	150.0	-	107.9	86.8	89.2	315.0	19.9	98.1	87.3	85.6	309.2	32.5
Test item	14.0	-	88.3	89.9	102.5	15.3	1.0	90.8	107.2	95.5	16.6	1.7
Test item	28.0	-	86.8	78.0	98.5	0.0	0.0	98.2	90.5	102.9	13.7	1.4
Test item	56.0	-	90.7	77.5	92.9	9.0	0.6	78.8	76.1	91.9	16.8	1.8
Test item	112.0	-	75.0	51.9	88.2	18.1	1.1	67.1	50.4	93.7	21.3	2.2
Test item	168.0	-	0.0	culture was not continued^#				0.0	culture was not continued^#
Test item	224.0	-	0.0	culture was not continued^#				0.0	culture was not continued^#
Experiment II / 4 h treatment
Solvent control with DMSO		+	100.0	100.0	100.0	18.5	1.0	100.0	100.0	100.0	22.0	1.0
Positive control (DMBA)	1.1	+	29.6	65.4	68.4	987.0	53.4	39.5	56.9	74.3	1056.5	48.1
Test item	28.0	+	102.3	115.9	89.9	6.5	0.4	92.2	92.0	75.5	16.7	0.8
Test item	56.0	+	103.2	115.5	78.1	15.6	0.8	101.7	101.3	121.6	10.9	0.5
Test item	112.0	+	101.8	126.2	90.8	23.4	1.3	98.2	96.8	127.8	11.0	0.5
Test item	224.0	+	100.5	103.0	99.5	17.5	0.9	96.8	91.0	93.5	14.8	0.7
Test item	336.0	+	24.6	66.3	97.8	21.7	1.2	17.3	35.9	99.1	3.2	0.1
Test item	448.0	+	0.0	culture was not continued^#				0.0	culture was not continued^#

^# culture was not continued due to exceedingly severe cytotoxic effects

Conclusions:

In conclusion it can be stated that under the experimental conditions reported the test item did not induce gene mutations at the HPRT locus in V79 cells. Therefore, the test substance propyl 4-hydroxybenzoate is considered to be non-mutagenic in this HPRT assay.

Executive summary:

The study was performed in two independent experiments, using identical experimental procedures. In the first experiment the treatment period was 4 hours with and without metabolic activation. The experimental part without metabolic activation was prematurely terminated due to microbial contamination. This part of the experiment was repeated as experiment IA. The data of experiment IA are reported as experiment I without metabolic activation. The second experiment was performed with a treatment time of 4 hours with and 24 hours without metabolic activation.

Relevant cytotoxic effects defined as a reduction of the relative cloning efficiency I and/or relative cell density to values below 50% in both parallel cultures were noted in the first experiment at 336.0 µg/mL with and at 93.0 µg/mL without metabolic activation. In the second experiment cytotoxic effects as described above occurred at 336.0 µg/mL with metabolic activation. In the experimental part of the second experiment without metabolic activation a very steep cytotoxic gradient was observed. Borderline cytotoxicity was noted at 112.0 µg/mL (relative cell density of 51.9 and 50.4%). Evaluation of any data on mutagenicity was impossible at the next higher concentration of 168.0 µg/mL as exceedingly severe cytotoxic effects completely inhibited the cell growth. The recommended cytotoxic range of approximately 10- 20% relative cloning efficiency I or relative cell density was covered with and without metabolic activation.

No relevant and reproducible increase in mutant colony numbers/10E06 cells was observed in the main experiments up to the maximum concentration. The mutation frequency remained within the historical range of solvent controls. The induction factor did not reach or exceed the threshold of 3 time the mutation frequency of the corresponding solvent control. A linear regression analysis (least squares) was performed to assess a possible dose dependent increase of mutant frequencies. A significant dose dependent trend of the mutation frequency indicated by a probability value of <0.05 was solely detected in the first culture of the first experiment with metabolic activation. This trend however, was judged as irrelevant since it actually was reciprocal, going down versus increasing concentrations.In both experiments of this study (with and without S9 mix) the range of the solvent controls was from 9.5 up to 22.0 mutants per 10E06 cells; the range of the groups treated with the test item was from 0.0 up to 27.3 mutant colonies per 10E06cells. EMS (150 µg/mL) and DMBA (1.1 µg/mL) were used as positive controls and showed a distinct increase in induced mutant colonies.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

other information

Reason / purpose for cross-reference:

read-across source

Reference 4

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 August 2018 to 07 December 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 487 (In vitro Mammalian Cell Micronucleus Test)

Version / remarks:

adopted on 29 July 2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian cell micronucleus test

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: external sample from China
- Expiration date of the batch: 27.10.2019
- Purity test date:99,7%

STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:Ambient (21 to 29°C)
- Solubility of the test substance in the solvent/vehicle:Dimethyl sulphoxide

Target gene:

Human lymphocytes

Species / strain / cell type:

lymphocytes:

Details on mammalian cell type (if applicable):

CELLS USED
- Source of cells: Human
- Cell cycle length, doubling time or proliferation index: 44 to 48 hours
- Sex, age and number of blood donors if applicable: male and female donors (21 and 33 years of age)
- Whether whole blood or separated lymphocytes were used if applicable: whole blood
- Modal number of chromosomes:46±2

MEDIA USED
- Type and identity of media including CO2 concentration if applicable: RPMI 1640, 5 PERCENT
- Properly maintained: yes

Cytokinesis block (if used):

cytochalasin B

Metabolic activation:

with and without

Metabolic activation system:

1 mL of S9 homogenate was mixed with 9 mL co factor

Test concentrations with justification for top dose:

As no cytotoxicity or precipitation observed, the highest test concentration correspond to 2 mg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: Test item was found soluble in dimethyl sulphoxide at 200 mg/mL

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

cyclophosphamide

mitomycin C

other: Colchicine

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: 3 to 6 hours and 20 to 22 hours


STAIN (for cytogenetic assays): Acridine orange

NUMBER OF REPLICATIONS: duplicates

METHODS OF SLIDE PREPARATION AND STAINING TECHNIQUE USED: Pellet were mixed with 3 mL of freshly prepared 0.56% Potassium chloride. Cell suspension was incubated for 10 minutes at room temperature and later it was centrifuged at 1800 rpm for 10 minutes. Supernatant was discarded and cell pellet was mixed with 3 mL of freshly prepared cold acetic acid:methanol fixative (1:3). Cells were incubated for 10 minutes at room temperature and later suspension was centrifuged at 2000 rpm for 10 minutes. The procedure was repeated twice by adding 3 mL of cold acetic acid: methanol fixative (1:3) and slides were prepared.
Clean slides were stored in a container with distilled and kept in the refrigerator for 1 hour before use. The cell suspension was mixed using a pipette and few drops of the suspension was aspirated and dropped onto the chilled slide pre labeled with study number, with (+S9) or without metabolic activation(-S9), treatment/group and slide number. The slides were air dried. Smear was stained using Acridine Orange stain by allowing the stain to retain for 5 minutes

NUMBER OF CELLS EVALUATED: 1000 per replicate


CRITERIA FOR MICRONUCLEUS IDENTIFICATION: Micronucleus in binucleates

DETERMINATION OF CYTOTOXICITY
- Method: Measurement of the relative frequencies of mononucleate, binucleate and multi-nucleate cells in the culture was made to determine cell proliferation and the cytostatic activity

Evaluation criteria:

Concurrent measures of cytotoxicity and/or cytostasis for all treated and vehicle control cultures was determined from each treatment.
The CBPI was calculated for all treated and control cultures as measurement of cell cycle delay.
Slides was evaluated for the presence of Micronucleus in at least 2000 Binucleates (at least 1000 per culture).

Statistics:

Data was analyzed using SPSS software version 22 for differences among vehicle control, positive control and test item groups using ANOVA following Dunnett’s test at a 95% level of confidence (p≤0.05) and the statistical significance was designated by the superscripts thoughout the study report as stated below.
*: Statistically significant (p≤0.05).

Key result

Species / strain:

lymphocytes:

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- pH: no change
- Water solubility: insolublle
- Precipitation: no


RANGE-FINDING/SCREENING STUDIES:

CYTOKINESIS BLOCK (if used) : Cytochalasin B
- Distribution of mono-, bi- and multi-nucleated cells: yes

NUMBER OF CELLS WITH MICRONUCLEI
- Number of cells for each treated and control culture: 1000 per culture
- Indication whether binucleate or mononucleate where appropriate: yes

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Measurement of cytotoxicity used:CBPI

Remarks on result:

other: .

Remarks:

Results are summerized in the next part

TABLE 1.      SUMMARY OF MICRONUCLEI INCIDENCE WITH METABOLIC ACTIVATION FOR 3 TO 6 HOURS

Treatment	Concentration mg/mL	Replicate No.	Average CBPI	Average % of Cytotoxicity	Total No. of Binucleates	Total No. of Micronucleus	Average Percentage of Micronucleus
Vehicle Control	0	1	1.62	0.0	2039	3	0.15
		2
Propylparaben	0.5	1	1.58	6.45	2099	4	0.19
		2
	1	1	1.56	9.68	2030	3	0.15
		2
	2	1	1.54	12.90	2035	5	0.25
		2
Cyclophosphamide Monohydrate	10 µg/mL	1	1.61	1.61	2007	26	1.30*
		2

TABLE 2.      SUMMARY OF MICRONUCLEI INCIDENCE WITHOUT METABOLIC ACTIVATION FOR 3 TO 6 HOURS

Treatment	Concentration      mg/mL	Replicate No.	Average CBPI	Average % of Cytotoxicity	Total No. of Binucleates	Total No. of Micronucleus	Average Percentage of Micronucleus
Vehicle Control	0	1	1.63	0.0	2016	3	0.15
		2
Propylparaben	0.5	1	1.61	3.17	2015	3	0.15
		2
	1	1	1.57	9.52	2071	3	0.15
		2
	2	1	1.54	14.29	2020	2	0.10
		2
Colchicine	0.03 µg/mL	1	1.61	3.17	2053	26	1.27*
		2

Table 3 SUMMARY OF MICRONUCLEI INCIDENCE WITHOUT METABOLIC ACTIVATION FOR 20 TO 24 HOURS

Treatment	Concentration      mg/mL	Replicate No.	Average CBPI	Average % of Cytotoxicity	Total No. of Binucleates	Total No. of Micronucleus	Average Percentage of Micronucleus
Vehicle Control	0	1	1.63	0.0	2031	3	0.15
		2
Propylparaben	0.5	1	1.59	6.35	2031	3	0.15
		2
	1	1	1.54	14.29	2018	3	0.15
		2
	2	1	1.44	30.16	2060	4	0.19
		2
Mitomycin C	0.075 µg/mL	1	1.60	4.76	2077	26	1.25*
		2

Conclusions:

Based on the results obtained in this study, it is concluded that the test item Propylparaben is non clastogenic and/or non aneugenic in cultured human lymphocytes at and up to 2 mg/mL both in short term and long term treatment, both in presence and absence of metabolic activation as it showed no evidence of increase in the induction of micronuclei under the test conditions.

Executive summary:

The test item was evaluated for the formation of micronuclei in the cytoplasm of interphase cells according to OECD TG 487  “In vitro Mammalian Cell Micronucleus Test” .Test item was found soluble in dimethyl sulphoxide at 200 mg/mL. Moderate and mild precipitation was observed at 2 and 1 mg/mL respectively. No precipitation was observed in any other concentration tested. No change in pH was observed in any of the concentrations tested. Hence, 2 mg/mL was selected as highest concentration for initial cytotoxicity test and other concentrations tested were 0.125, 0.25, 0.5, 1 and 2 mg/mL using DMSO as a vehicle. The experiment was conducted with and without metabolic activation. The test item was assessed in proliferated lymphocytes in duplicates by exposing for a short term (3 to 6 hours, with and without metabolic activation) and a long term (20 to 24 hours, without metabolic activation).

Cytokinesis was blocked using Cytochalasin B, the cells were harvested and slides were prepared. In order to assess the cytotoxicity of the test item, the Cytokinesis-Block Proliferation Index (CBPI) was calculated for cultures treated with the test item and vehicle control.  

In initial cytotoxicity test, the test item at the concentrations of 0.125, 0.25, 0.50, 1 and 2 mg/mL resulted in a percentage reduction of average Cytokinesis-Block Proliferation Index (CBPI) was in the range of 1.67 to 30.00 at the tested concentrations in both short term and long term treatment. The percentage reduction of average Cytokinesis-Block Proliferation Index (CBPI) was not greater than 45±5% at 2 mg/mL. Hence 2 mg/mL was selected as highest concentration for the micronucleus test. Other concentrations tested were 0.5 and 1 mg/mL.

In micronucleus test, the test item was tested at the concentrations of 0.5, 1 and 2 mg/mL for short term in presence and absence of metabolic activation and long term treatment in the absence of metabolic activation system. The test item did not induced cytotoxicity up to 2 mg/mL when compared to vehicle control. No statistical significant increase in the percentage of micronuclei in binucleated cells observed in any of the tested concentration when compared to the vehicle control. The positive controls resulted increase in the micronuclei frequency with statistical significance at 95% level of confidence (p<0.05) under identical conditions, when compared with the vehicle control. This demonstrated the sensitivity of test system towards positive control and confirmed that the test conditions were adequate and within the range of historical control.

Conclusion

Based on the results obtained, it is concluded that the test item Propylparaben is non clastogenic and/or non aneugenic in cultured human lymphocytes at and up to 2 mg/mL both in short term and long term treatment, both in presence and absence of metabolic activation as it showed no evidence of increase in the induction of micronuclei under the test conditions.

Reference 5

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

other information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Reference 6

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Documentation is insufficient for assessment. No data on positive and negative controls.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

his, trp

Species / strain / cell type:

S. typhimurium, other: TA 100, TA 98

Species / strain / cell type:

E. coli WP2

Metabolic activation:

with and without

Metabolic activation system:

Cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of Sprague-Dawley rats treated with polychlorinated biphenyl (KC-500) or phenobarbital.

Test concentrations with justification for top dose:

no data

Untreated negative controls:

not specified

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

not specified

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 min
- Exposure duration:48 h

Key result

Species / strain:

S. typhimurium, other: TA 100, TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Key result

Species / strain:

E. coli WP2

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Conclusions:

In conclusion, it can be stated that during the described mutagenicity test in bacteria and under the experimental conditions reported, propyl 4-hydroxybenzoate did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, propyl 4-hydroxybenzoate is considered to be non-mutagenic in this bacterial reverse mutation assay.

Executive summary:

A bacterial gene mutation assay with propyl 4-hydroxybenzoate was performed according to a protocol similar to OECD Guideline 471 (Sugimura, 1976). Using the pre-incubation method, the Salmonella typhimurium strains TA 100, TA 98 were exposed to the test substance for 48 h with and without metabolic activation and E. coli strain WP2 was exposed to the test substance for 48 h without metabolic activation. No concentration range was given. The test substance did not induce a significant increase in the mutation frequency of the tester strains in the presence and absence of metabolic activation. Therefore, the test substance is considered to be non-mutagenic in this bacterial reverse mutation assay.

Reference 7

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Only two standard S. typhimurium strains (TA 1535, TA 1537) were used at one test substance concentration and the incubation period for the plate incorporation assay was 96 h instead of 48 - 72 h

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

only two standard S. typhimurium strains (TA 1535, TA 1537) were used at one test substance concentration, the incubation period for the plate incorporation assay was 96 h instead of 48 - 72 h

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

his

Species / strain / cell type:

S. typhimurium, other: TA 1535, TA 1537, TA 1538

Metabolic activation:

with and without

Metabolic activation system:

Cofactor supplemented post-mitochondrial fraction (S9 mix), prepared from the livers of Sprague-Dawley rats, ICR mice and Macaca mulatta primates.

Test concentrations with justification for top dose:

0.075%

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: dimethylsulfoxide (DMSO)

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: with S9: Dimethylnitrosamine (TA 1535), 2-Acetylaminofluorene (TA 1537, TA 1538); without S9: Ethyl methanesulfonate (TA 1535), 2-Nitrofluorene (TA 1538), Quinacrine mustard (TA 1537)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 1 h
- Exposure duration: 96 h (plate incorporation); 48 h (preincubation)

NUMBER OF REPLICATIONS: duplicates in two independent assays

DETERMINATION OF CYTOTOXICITY
- Method: relative total growth

Key result

Species / strain:

S. typhimurium, other: TA 1535, TA 1537, TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES: The solubility, toxicity and appropriate doses for all chemical were determined prior to the main study at concentrations of 0.0005 to 5%.

ADDITIONAL INFORMATION ON CYTOTOXICITY: In the range-finding test, the cytotoxicity was determined at different concentrations. A survival of 50% of the bacteria was found at 0.15%.

Table 1: Bacterial Reverse Mutation Assay, plate incorporation assay

Bacterial Reverse Mutation Assay, mean revertants colonies/plate
EXPERIMENT 1 (plate incorporation assay)
S9-Mix	Without
Test item (%)	TA1535		TA1537		TA 1538
DMSO	11	20	4	5	15	11
0.075	5	4	1	5	5	11
EMS	> 10^5	> 10^5	---		---
QM	---		193	207	---
NF	---		---		145	134
S9-Mix	With
Test item (%)	TA1535		TA1537		TA 1538
DMSO	20	24	5	9	15	14
0.075 (mouse)	2	5	1	5	9	12
0.075 (rat)	2	4	7	9	4	4
0.075 (primate)	2	3	3	5	3	7
DMNA (mouse)	> 1000	> 1000	---		---
DMNA (rat)	> 1000	> 1000	---		---
DMNA (primate)	273	356	---		---
AAF (mouse)	---		39	34	343	357
AAF (rat)	---		89	88	347	341
AAF (primate)	---		30	33	123	119
EMS: Ethyl methanesulfonate QM: Quinacrine mustard NF: 2-Nitrofluorene DMNA: Dimethylnitrosamine AAF: 2-Acetylaminofluorene

Table 2: Bacterial Reverse Mutation Assay, preincubation assay

Bacterial Reverse Mutation Assay, mean revertants colonies/plate
EXPERIMENT 2 (preincubation assay)
S9-Mix	Without
Test item (%)	TA1535				TA1537				TA 1538
DMSO	10.15				2.10				9.02
0.075	21.19		18.20		4.20		2.73		10.66		9.11
EMS	273.70				---				---
QM	---				225.89				---
NF	---				---				145.97
S9-Mix	With
Test item (%)	TA1535				TA1537				TA 1538
DMSO	6.7’	11.6’’		7.0’’’	2.9’	0.6’’		7.0’’’	10.5’	5.4’’		5.6’’’
0.075 (mouse)	9.17		9.71		2.67		2.58		23.02		19.05
0.075 (rat)	15.62		11.32		0.56		0.52		15.03		11.64
0.075 (primate)	15.38		6.53		4.19		7.82		1.71		3.30
DMNA (mouse)	1168.86				---				---
DMNA (rat)	1500				---				---
DMNA (primate)	1352.79				---				---
AAF (mouse)	---				10.07				37.43
AAF (rat)	---				7.28				59.37
AAF (primate)	---				19.31				24.13
EMS: Ethyl methanesulfonate QM: Quinacrine mustard NF: 2-Nitrofluorene DMNA: Dimethylnitrosamine AAF: 2-Acetylaminofluorene ’ mouse S9-Mix ’’ rat S9-Mix ’’’ primate S9-Mix

Conclusions:

In conclusion, it can be stated that during the described mutagenicity test in bacteria and under the experimental conditions reported, propyl 4-hydroxybenzoate did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, propyl 4-hydroxybenzoate is considered to be non-mutagenic in this bacterial reverse mutation assay.

Executive summary:

A bacterial gene mutation assay with propyl 4-hydroxybenzoate was performed similar to OECD Guideline 471 and in compliance with GLP (Brusick, 1975) is available and used as supporting study. In two independent experiments, the Salmonella typhimurium strains TA 1535, TA 1537 and TA 1538 were exposed to the test substance for 96 and 48 h in the plate incorporation (Exp.1) and pre-incubation method (Exp.2), respectively. Based on the results of a pre-experiment, a survival of 50% of the bacteria was found at 0.15%, test substance concentrations of 0.075% were selected for the incubation with and without metabolic activation in both main experiments. No cytotoxicity was observed in the main experiments with and without metabolic activation. In the concentration range investigated, the test substance did not induce a significant increase in the mutation frequency of the tester strains in the presence and absence of metabolic activation. Therefore, the test substance is considered to be non-mutagenic in this bacterial reverse mutation assay.

Reference 8

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Original reference not translated (Japanese).

GLP compliance:

no

Type of assay:

other: in vitro mammalian chromosome aberration test (migrated information)

Species / strain / cell type:

other: Chinese Hamster firbrobalst cells

Metabolic activation:

not specified

Test concentrations with justification for top dose:

up to 0.125 mg/mL (maximum tolerated concentration on cells)

Vehicle / solvent:

- Vehicle/solvent used: Ethanol

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

not specified

Key result

Species / strain:

other: Chinese Hamster fibrobalst cells

Metabolic activation:

not specified

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

not specified

Additional information on results:

After 48 h, in 3% of the cells chromosome aberration was noticed. The aberration types observed were breaks.

Conclusions:

The results of available in vitro cytogenicity studies performed with test substance propyl 4-hydroxybenzoate in mammalian cells was negative.

Executive summary:

An in vitro mammalian chromosome aberration test in Chinese Hamster fibroblasts was performed with propyl 4-hydroxybenzoate (Ishidate, 1978). Treatment with the test substance at concentrations of up to 0.125 mg/mL in ethanol (maximum tolerated concentration on cells) for 48 h induces chromosome aberration (breaks) in 3% of the cells. Therefore, the test substance is considered to be non-clastogenic in this in vitro chromosome aberration assay. Since no results are available for the negative control and the original study report is not translated (Japanese), reliability was not assignable.

Reference 9

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

See attached read-cross justification (chapter 13)

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

other: Chinese Hamster fibroblast cells

Metabolic activation:

not specified

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

not specified

Additional information on results:

After 48 h, in 3% of the cells chromosome aberration was noticed. The aberration types observed were breaks.

Conclusions:

The result of an available in vitro cytogenicity study performed with source substance propyl 4-hydroxybenzoate in Chinese Hamster fibroblastswas negative. Therefore, as explained in the analogue justification the target substance is not expected to show clastogenic properties in vitro.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Justification for classification or non-classification

Based on the analogue read-across approach, the available data on genetic toxicity do not meet the classification criteria according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification.