1,4-dimethoxybenzene

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: No GLP conditions

Data source

Reference

Reference Type:

publication

Title:

Salmonella mutagenicity test results for 250 chemicals

Author:

HAWORTH S, LAWLOR T, MORTELMANS K, SPECK W, ZEIGER E

Year:

1983

Bibliographic source:

Environ. Mutagenesis Supplement vol. 5, sup. 1, p : 3-142

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: NTP protocols

Deviations:

no

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

1,4-dimethoxybenzene

EC Number:

205-771-9

EC Name:

1,4-dimethoxybenzene

Cas Number:

150-78-7

Molecular formula:

C8H10O2

IUPAC Name:

1,4-dimethoxybenzene

Details on test material:

Test material identity: From Aldrich
lot/batch No: MC 022287.
Analytical purity: 98%

Method

Species / strain

Species / strain / cell type:

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

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Induced S9 mix with Aroclor 1254, from rat or hamster liver cells.

Test concentrations with justification for top dose:

0; 10; 33; 100; 333; 666; 750; 900; 1000; 2000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: solubility of the test material

Controls

Untreated negative controls:

yes

Remarks:

choline chloride, glycerol, glycine, mannitol and sodium phosphate.

Negative solvent / vehicle controls:

yes

Remarks:

culture medium

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene on all strains with rat (1.5 µg/plate) and hamster (0.75 µg/plate) S9; 4-Nitro-o-phenylenediamine on TA98 without S9 (12µg/plate); sodium azide on TA100 and TA1535 without S9 (2.5 µg/plate); 9-aminoacridine on TA1537 (80 µg/plate)

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation with S9 mix or buffer
DURATION
- pre-incubation period: 20 min at 37°C
- Exposure duration of incubation: 48 h at 37°C

Evaluation criteria:

Although procedures for the statistical analysis of Salmonella plate test data have been developed [Margolin et al, 1981], they were not incorporated
into the initial data evaluations. The data were evaluated in an ad hoc manner by each testing laboratory and by NTP personnel. Prior to statistical
analysis no formal rules were used; however, a positive response was indicated by a reproducible, dose-related increase, whether it be twofold over
background or not. The matrix of test strains and activation systems used allowed the investigators to detect trends or patterns that might not be
as evident if only one strain and activation system were examined. In addition to the standard "positive" and "negative" categories, there is also
"questionable" (or "inconclusive"). This applied to low-level responses that were not reproducible within the laboratory or to results that showed a
definite trend but with which the investigator did not feel comfortable in making a " +" or " -" decision. It also included tests in which an elevated
revertant colony yield occurred at only a single dose level. After a decision on the mutagenicity of a sample was made, a request to decode the
sample was sent to the repository, and the code was broken.

Statistics:

The data were subsequently evaluated using an analysis based on the models presented by Margolin et al [1981]. As a result of these statistical
analyses, a number of calls were changed from the original "negative" to "equivocal." The statistical analysis did not result in any "positive" or
"equivocal" calls being called "negative".
Because the criteria for "positive" or "questionable" decisions have evolved during the course of the study and because the recent use of statistical
analysis, some of the results differ from the initial evaluations published in the NTP Technical Bulletins (1980 to 1983).

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:

cytotoxicity

Remarks:

yes, slight to toxic for all strains at high concentrations

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

 Strain: TA1535

Dose	No Activation (Negative)		No Activation (Positive)		No Activation (Negative)		No Activation (Negative)		10% HLI (Negative)		10% HLI (Negative)		10% RLI (Negative)		10% RLI (Negative)
Dose units	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM
0	23	2	13	1.8	26	1.2	11	2.6	9	1.8	7	1.2	11	0.9	11	0.9
10			20	1.7							6	0.9			6	0.6
33	33	1.7	21	2.6	21	4.2	17	1	13	1.3	7	2	10	1	9	2.5
100	27	2	23	0.7	18	3.8	10	0.7	11	0.6	7	1.2	14	3.5	9	2.7
333	24	6.4	41	1.5	21	1.8	15	1.8	9	2	8	1.5	10	1.8	6	1.2
666			106	3	23s	0.6	14s	1			7	1.2			7	1.2
750					18s	1.5	13s	1.9
900					14s	5.8	8s	4.1
1000	T								11s	0.5			5s	1
2000	T								T				T
Positive Control	1408	20.8	1446	11.7	2002	67.1	1413	91.8	148	6.8	85	5.9	77	1	53	8.

Strain: TA100

Dose	No Activation (Equivocal)		No Activation (Weak Positive)		No Activation (Negative)		No Activation (Negative)		10% HLI (Negative)		10% HLI (Negative)		10% RLI (Negative)		10% RLI (Negative)
Dose units	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM
0	97	2.1	82	5	103	11.9	108	6.7	85	6.9	82	6.1	92	13.2	81	6.2
10			88	12.9							83	8.6			70	8.1
33	108	9.8	91	4.3	99	4.5	103	15.9	91	3.8	75	2.2	98	6.2	74	2.9
100	124	2	99	9.5	105	8.5	107	7.6	84	6.5	106	8.4	98	4.3	82	8.4
333	109	5.4	141	2.3	96	4.7	94	8.7	92	5.2	83	0.9	99	9	81	8.9
666			246	17.2	101	3.8	114s	12.7			75	5			84	3.5
750					105s	8.1	116s	10.1
900					74s	33.5	62s	27
1000	T								69s	9.5			T
2000	T								T				T
Positive Control	1919	39.3	2152	99.5	2173	58.7	1590	94.7	1634	59.6	861	16.2	1303	116.4	457	35.9

Strain: TA98

Dose	No Activation (Negative)		No Activation (Negative)		10% HLI (Negative)		10% HLI (Negative)		10% RLI (Negative)		10% RLI (Negative)
Dose units	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM
0	19	2.5	18	5.1	29	3.3	23	0.9	20	3.8	22	2.9
10			16	3.6			16	1.7			21	2.4
33	14	0.9	17	3.8	27	2.3	22	3.2	22	1.2	24	0.7
100	17	2.3	20	4.1	29	2.4	22	3	19	4.1	22	3.1
333	16	1.5	15	3.3	23	0.9	15	1.9	33	1.7	21	1.2
666			14	3.3			21	1.5			20	1.2
1000	T				27s	6.5			T
2000	T				T				T
Positive Control	1174	17.5	1352	55.2	983	53.9	808	31.9	529	73.4	532	18.2

  Strain: TA1537

Dose	No Activation (Negative)		No Activation (Negative)		10% HLI (Negative)		10% HLI (Negative)		10% RLI (Negative)		10% RLI (Negative)
Dose units	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM	Mean	± SEM
0	8	1.9	3	0.6	10	1.7	5	0.7	10	1	6	2.6
10			5	1.2			6	0.3			5	0.6
33	6	0.7	4	1.2	9	0.3	4	1.2	7	1.5	3	0.3
100	6	0.9	3	0.9	7	0.7	3	0.7	10	3.7	4	0.6
333	8	1.3	4	1.2	10	2.3	5	0.7	9	0.9	8	2.5
666			5	0.7			5	1.2			7	3.7
1000	T				8s	1			9s	2.6
2000	T				T				T
Positive Control	383	200.3	518	52.7	206	29.5	105	14.5	73	4.7	58	3.5

Applicant's summary and conclusion

Conclusions:

Negative with and without metabolic acivation.

Executive summary:

In a reverse gene mutation assay in bacteria (Haworth, 1983), strains TA98, TA100, TA1535 and TA1537 of S. typhimurium were exposed to paradimethoxybenzene at concentrations of 0 to 2000 µg/plate in the presence and absence of mammalian metabolic activation (rat or hamster liver cells).

 

Paradimethoxybenzene was tested up to cytotoxic concentrations.

The positive controls induced the appropriate responses in the corresponding strains.   There was no evidence of induced mutant colonies over background.

 

This study is classified as acceptable.  This study satisfies the requirement for Test Guideline  OECD 471 for in vitro mutagenicity bacterial reverse gene mutation data.