Benzenesulfonic acid, 4-C15-16-sec-alkyl derivs.

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

with and without activation

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TA 1538 also tested negative. During the pre-incubation test, signs of toxicity were noted at concentrations as low as 125 ug/plate. No precipitation of the product was observed at any concentration tested.

Conclusions:

LAS is not mutagenic in the Ames test.

Executive summary:

A bacterial mutagenicity study (Ames test) was conducted on LAS and was found to be negative for mutagenicity.

Reference 2

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

preliminary test showed cytotoxicity at >= 50 ug/ml without S9, and >= 100 ug/ml with S9.

Vehicle controls validity:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

COMPARISON WITH HISTORICAL CONTROL DATA: In both the studies with and without S9, the mutant frequencies in the treated groups were statistically significantly higher than in the concurrent negative controls. However, the mutant frequencies in the treated groups were not significantly increased when compared to historical negative controls. There was also no dose-response relationship. The increased mutant frequency in treated groups was therefore not considered to be biologically significant.

Results of Test 1 - Without S9 Mix            

Concentration (ug/ml)	Absolute cloning efficiency (%)	Mutant frequency ( x 10^6)
0	82	3 ± 2
0.6	86	7 ± 1
1	85	3 ± 2
1.8	78	5 ± 2
3	86	1 ± 1
6	83	0 ± 1
EMS	83	277 ± 17

Results of Test 1 - With S9 Mix     

Concentration (ug/ml)	Absolute cloning efficiency (%)	Mutant frequency ( x 10^6)
0	90	2 ± 1
6	88	1 ± 1
10	84	9 ± 4
18	78	5 ± 3
30	89	3 ± 2
60	89	7 ± 2
MCA	81	91 ± 9

Results of Test 2 - Without S9 Mix

Concentration (ug/ml)	Absolute cloning efficiency (%)	Mutant frequency ( x 10^6)
0	96	1 ± 1
0.6	92	2 ± 3
1	95	1 ± 1
1.8	93	5 ± 2
3	90	2 ± 1
6	91	6 ± 6
EMS	90	309 ± 20

Results of Test 2 - With S9 Mix     

Concentration (ug/ml)	Absolute cloning efficiency (%)	Mutant frequency ( x 10^6)
0	90	2 ± 1
6	92	7 ± 3
10	88	9 ± 2
18	94	2 ± 1
30	93	2 ± 2
60	90	5 ± 1
MCA	95	89 ± 6

Conclusions:

Interpretation of results (migrated information):
negative

The test substance is not mutagenic in either the presence or absence of metabolic activation.

Executive summary:

This study examined the potential of the test substance to cause mutations in mammalian cells. Chinese Hamster Ovary (CHO) cells were exposed to concentrations of 0, 0.6, 1, 1.8, 3, and 6 ug/ml without S9, and 0, 6, 10, 18, 30, and 60 ug/ml with S9. The cells were then examined for cytogenicity and mutation frequency. Ethyl methane sulfonate and 3-(20-)methylcholanthrene were used as positive control substances. The test substance was cytogenic at concentrations of 50 ug/ml or greater with metabolic activation, and 100 ug/ml or above without metabolic activation. There was no biologically significant increase in mutation frequency in the treated groups. The test substance is considered not mutagenic to CHO cells both in the presence and absence of S9.

Reference 3

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

Chinese hamster Ovary (CHO)

Metabolic activation:

with and without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

>= 15 microgram/ml with S9, >=58 microgram/ml without S9

Vehicle controls validity:

not examined

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

In the absence of S9, only one culture (Test 2, 24 hr harvest, 20 ug/ml) showed a suspicious result. This single result was considered sporadic, as other cultures at this concentration, or at higher concentrations did not show a positive response. In Test 1, in the absence of S9, cytoxicity was seen at 78 micrograms/ml and above. In Test 2, in the absence of S9, cytoxicity was seen at concentrations of 58 micrograms/ml and above.

In Test 1, in the presence of S9, no positive results were seen at concentrations of up to 20 micrograms/ml. Metaphases could not be analyzed due to severe cytotoxicity at the 39 and 78 microgram/ml concentrations. In Test 2, in the presence of S9, one of the cultures at the 5 microgram/ml concentration gave a suspicious result, and both cultures at the 10 microgram/ml concentrations gave positive responses. Mild cytotoxity was also seen at the 10 microgram/ml concentration. At concentrations at and above 20 micrograms/ml, metaphases could not be analyzed due to severe cytotoxicity. No positive results were seen in the Test 2, 48 hr harvest cultures grown in the presence of S9, though moderate cytotoxicity was seen in one of the 20 microgram/ml cultures, and severe cytotoxicity was seen in all cultures above this concentration.

A third test was done in the presence of S9, which showed positive results at the 15 micrograms/ml concentration. However, this concentration was also moderately cytotoxic with only 26% of cells survival. However, due to the low survival of cells, these results are not definitive for determining clastogenicity. Higher concentrations were completely cytotoxic. An additional assessment was then performed at 10 micrograms/ml in the presence of S9, with negative results.

Abbreviations used in tables:

T - Toxicity evident from morphological changes

TT- Toxicity evident from reduced cell count (<60% of vehicle)

TTT- Too toxic for metaphase assessment

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham's F10 medium	0.01	1	0	Nil
Ham's F10 medium	0.02	1	1	Nil
0.32	-	-	-	Nil
0.32	-	-	-	Nil
0.63	-	-	-	Nil
0.63	-	-	-	Nil
1.25	-	-	-	Nil
1.25	-	-	-	Nil
2.5	0.01	1	0	Nil
2.5	0.00	0	0	Nil
5	0.00	0	0	Nil
5	0.05	5	0	Nil
10	0.01	1	0	Nil
10	0.01	1	0	Nil
20	0.00	0	0	Nil
20	0.00	0	0	Nil
39	-	-	-	TTT
39	-	-	-	TTT
78	-	-	-	TTT
78	-	-	-	TTT
Cyclophosphamide (20 micrograms/ml)	0.14	8	4	-
Cyclophosphamide (30 micrograms/ml)	0.06	4	4	-
Cyclophosphamide (40 micrograms/ml)	0.33	20	19	-

Test 1 - Without S9 Mix, 24 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham's F10 medium	0.00	0	0	Nil
Ham's F10 medium	0.00	0	0	Nil
1.25	-	-	-	Nil
1.25	-	-	-	Nil
2.5	-	-	-	Nil
2.5	-	-	-	Nil
5	-	-	-	Nil
5	-	-	-	Nil
10	-	-	-	Nil
10	-	-	-	Nil
20	-	-	-	Nil
20	-	-	-	Nil
39	0.01	1	0	Nil
39	0.00	0	0	Nil
58	0.01	1	0	Nil
58	0.00	0	0	Nil
78	0.00	0	0	T
78	0.00	0	0	T
156	-	-	-	TTT
156	-	-	-	TTT
Methyl methane-sulphonate (10 micrograms/ml)	0.03	3	1	-
Cyclophosphamide (20 micrograms/ml)	0.16	14	10	-

Test 2 - With S9 Mix, 24 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham's F-10 medium	0.01	1	0	Nil
Ham's F-10 medium	0.02	2	1	Nil
2.5	0.07	2	1	Nil
2.5	0.04	3	1	Nil
5	0.04	3	2	Nil
5	0.06	6	4	Nil
10	0.12	8	6	T
10	0.19	13	5	T
20	-	-	-	TTT
20	-	-	-	TTT
26	-	-	-	TTT
26	-	-	-	TTT
33	-	-	-	TTT
33	-	-	-	TTT
39	-	-	-	TTT
39	-	-	-	TTT
Cyclophosphamide (40 micrograms/ml)	0.38	20	17	-
Cyclophosphamide (50 micrograms/ml)	0.31	18	11	-

Test 2 - With S9 Mix, 48 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham's F-10 medium	0.00	0	0	Nil
Ham's F-10 medium	0.00	0	0	Nil
2.5	0.01	1	0	Nil
2.5	0.01	1	1	Nil
5	0.00	0	0	Nil
5	0.02	2	2	Nil
10	0.03	2	1	Nil
10	0.02	2	1	TT
20	-	-	-	TTT
20	-	-	-	TTT
26	-	-	-	TTT
26	-	-	-	TTT
33	-	-	-	TTT
33	-	-	-	TTT
39	-	-	-	TTT
39	-	-	-	TTT
Cyclophosphamide (40 micrograms/ml)	0.03	3	2	-
Cyclophosphamide (50 micrograms/ml)	0.10	8	7	-

Test 2 ¿ Without S9 Mix, 24 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham¿s F-10 medium	0.02	2	2	Nil
Ham¿s F-10 medium	0.03	3	0	Nil
20	0.02	2	0	Nil
20	0.05	5	3	Nil
39	0.02	2	1	Nil
39	0.04	4	0	Nil
58	0.01	1	1	Nil
58	0.06	6	1	Nil
78	-	-	-	TTT
78	-	-	-	TTT
104	-	-	-	TTT
104	-	-	-	TTT
130	-	-	-	TTT
130	-	-	-	TTT
156	-	-	-	TTT
156	-	-	-	TTT
Methyl methane-sulphonate (10 micrograms/ml)	0.30	21	14	-
Methyl methane-sulphonate (20 micrograms/ml)	0.71	33	28	-

Test 2 - Without S9 Mix, 48 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytotoxicity
Ham's F-10 medium	0.01	1	1	Nil
Ham's F-10 medium	0.00	0	0	Nil
20	0.00	0	0	Nil
20	0.00	0	0	Nil
39	0.01	1	1	Nil
39	0.00	0	0	Nil
58	0.00	0	0	T
58	0.01	1	0	T
78	-	-	-	TTT
78	-	-	-	TTT
104	-	-	-	TTT
104	-	-	-	TTT
130	-	-	-	TTT
130	-	-	-	TTT
156	-	-	-	TTT
156	-	-	-	TTT
Methyl methane-sulphonate (20 micrograms/ml)	0.21	11	8	-
Methyl methane- sulphonate (40 micrograms/ml)	3.20	60	60	-

Test 3 - With S9 Mix, 24 hr Harvest

Concentration (micrograms/ml)	Aberration Frequency (lesions/cell)	Aberrant Cell Frequency (% Including Gaps)	Aberrant Cell Frequency (% Excluding Gaps)	Cytoxicity
Ham's F-10 medium	0.04	4	0	Nil
Ham's F-10 medium	0.04	4	0	Nil
2.5	-	-	-	Nil
2.5	-	-	-	Nil
5	-	-	-	Nil
5	-	-	-	Nil
7.5	-	-	-	Nil
7.5	-	-	-	Nil
10	-	-	-	Nil
10	-	-	-	Nil
15	0.20	12	8	TT
15	0.18	12	6	TT
20	-	-	-	TTT
20	-	-	-	TTT
25	-	-	-	TTT
25	-	-	-	TTT
30	-	-	-	TTT
30	-	-	-	TTT
Cyclophosphamide (30 micrograms/ml)	0.24	14	12	-
Cyclophosphamide (40 micrograms/ml)	0.32	17	11	-

Test 3 - see tables below

Conclusions:

Interpretation of results (migrated information):
negative without metabolic activation
positive with metabolic activation at cytotoxic concentrations or above

The test substance is not clastogenic in the absence of metabolic activation. The test substance is also not clastogenic in the presence of metabolic activation at non-cytotoxic concentrations. At cytotoxic concentrations, the test substance is weakly clastogenic.

Executive summary:

This study examined the potential of the test substance Marlon A 350 to cause chromosomal aberrations in mammalian cells. Chinese hamster ovary cells were exposed to concentrations of 0.32 to 78 ug/ml with S9, and 1.25 to 156 ug/ml without S9. Methyl methanesuflphonate and cyclophosphamide were used as positive controls. No biologically significant results were seen in treated cultures in the absence of metabolic activation. Positive responses were seen at cytotoxic concentrations in the presence of S9. Concentrations below the level of cytotoxicty with S9 did not show positive results. The test substance is not clastogenic in the absence of metabolic activation, or with metabolic activation below cytotoxic concentrations. These results indicate that LAS is weakly clastogenic at cytotoxic concentrations but negative at concentrations below cytotoxic concentrations

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

In vivo genotoxicity data indicate that the read-across source substance LAB Sulfonic Acids are not clastogenic. Additional data is available on LAS which provides suitable read across for LAB Sulfonic Acids as both form the identical chemical species in aqueous solutions at neutral (physiological) pH, namely, the LAS ion (C10-13 linear alkyl benzene-SO3-) and would be expected to have similar toxicological properties. LAS (read across) was consistently found not to cause induction of gene mutations in the Ames bacterial reverse mutation assay as well as in the OECD 476 in vitro mammalian cell gene mutation test. LAS (read across) was found to be weakly positive at cytotoxic concentrations, but negative at concentrations below cytotoxic concentrations, when tested in an in vitro chromosome aberration assay in CHO cells. When tested in a series of in vivo genotoxicity studies, LAS (read across) was consistently found to not cause any clastogenic or mutagenic responses. The positive result in the in vitro chromosome aberration study using a rodent cell line (CHO cells) derived from cancer tissues that is lacking proper cell cycle control has to be seen in the context of the extensive in vivo data. In vivo studies do assess genotoxicity under more realistic conditions, including exposure, and therefore the negative results in the in vivo studies together with the negative results in the Ames test do strongly indicate that LAS (read-across) and the read-across source substance LAB Sulfonic Acids do not have mutagenic or clastogenic potential in vivo.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

No significant increases in the number of polychromatic erythrocytes with micronuclei were observed.

Conclusions:

Interpretation of results (migrated information): negative

Executive summary:

No significant increases in the number of polychromatic erythrocytes with micronuclei were observed.

Reference 2

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

not examined

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

No significant differences in the incidence of chromosomal aberrations were observed in any test substance treatment group relative to the controls.

Chromosome Aberrations

	Total number of cells having aberrations and occurrence (%)
	6 hrs	24 hrs	48 hrs	5 days
200 mg/kg	0 (0)	0 (0)	0 (0)	1 (0.7)
400 mg/kg	1 (0.7)	0 (0)	0 (0)	0 (0)
800 mg/kg	0 (0)	0 (0)	0 (0)	0 (0)
800 mg/kg of 17.1% detergent	0 (0)	0 (0)	0 (0)	-
1600 mg/kg of 17.1% detergent	0 (0)	1 (0.7)	0 (0)	-
3200 mg/kg of 17.1% detergent	2 (1.3)	2 (1.3)	0 (0)	-
1000 mg/kg of 19% detergent	-	0 (0)	-	-
2000 mg/kg of 19% detergent	-	0 (0)	-	-
4000 mg/kg of 19% detergent	-	0 (0)	-	-
Mitomycin C	16 (10.7)	53 (353)	13 (8.7)	112 (74.7)
Distilled water	0 (0)	0 (0)	0 (0)	0 (0)
untreated	0 (0)	0 (0)	1 (0.7)	0 (0)

Conclusions:

Interpretation of results (migrated information): negative
The test substance is not clastogenic.

Executive summary:

Groups of male mice were given doses of 200, 400, or 800 mg/kg of Benzenesulfonic acid, C10-14-alkyl derivs., sodium salts. At 6, 24, and 48 hrs, 3 of the mice from each dosage group were sacrificed. The bone marrow cells from the femurs were collected and examined for chromosome aberrations. In addition, one group of mice was exposed daily for 5 consecutive days. Additional groups of mice were exposed to commerical detergents containing 19% or 17.1% of the test substance. Mitomycin C was used as a positive control. None of the treatment groups showed any significant increase in chromosome aberrations as compared to negative controls. The test substance in not clastogenic.

Reference 3

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male

Genotoxicity:

negative

Negative controls validity:

valid

Additional information on results:

No increase in chromosome aberrations was noted.

Chromosome Aberrations

	0.9% in Diet	Control
No. of cells with chromatid breaks	1	2
No. of cells with isochromatid breaks	1	0
No. of cells with chromatid gaps	4	5
No. of cells with isochromatid gaps	0	0
No. of cells with other aberrations	0	0

Conclusions:

Interpretation of results (migrated information): negative
The test substance is not clastogenic.

Executive summary:

A group of 5 male mice was fed a diet containing 0.9% test substance for 9 months. At the end of this period, the animals were sacrificed, and the bone marrow cells examined for chromosome aberrations. No increase in chromosome aberrations was seen as compared to controls. The test substance is not clastogenic.

Reference 4

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male

Genotoxicity:

negative

Negative controls validity:

valid

Additional information on results:

No increase in chromosome aberrations was noted.

Chromosome Aberrations

	0.9% in Diet - Wister Rats	0.9% in Diet - SD Rats	Control	Control
No. of cells with chromatid breaks	0	0	1	0
No. of cells with isochromatid breaks	0	0	0	0
No. of cells with chromatid gaps	3	4	3	4
No. of cells with isochromatid gaps	0	0	0	0
No. of cells with other aberrations	0	0	0	0

Conclusions:

Interpretation of results (migrated information): negative
The test substance is not clastogenic.

Executive summary:

Groups of 5 male rats were fed a diet containing 0.9% test substance for 9 months. At the end of this period, the animals were sacrificed, and the bone marrow cells examined for chromosome aberrations. No increase in chromosome aberrations was seen as compared to controls. The test substance is not clastogenic.

Reference 5

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see read-across document

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male

Genotoxicity:

negative

Negative controls validity:

valid

Additional information on results:

There were no significant differences in fertility, the mortality of ova and embryos, the number of surviving fetuses, or the index of dominant lethal induction between the experimental groups and the control group.

Dominant Lethal Assay Results

	0.6% in Diet	Control
Number of mating females	14	18
Number pregnant	11	12
No. with dead embryos	6	10
Dead embryos per pregnant female	54.6%	83.3%
No. of corpora lutea	156	161
Corpora lutea per pregnant female	14.2	13.4
No. of implants	148	156
Implants per pregnant female	13.5	13.0
Implants per corpora lutea	94.9	96.9
No. of live fetuses	142	143
Live fetuses per pregnant female	12.9	11.9
Live fetuses per corpora lutea	91.0	88.8
Live fetuses per total implants	96.0	91.7
No. of early dead fetuses	4	12
No. of late dead fetuses	2	1
% of dominant lethals	-4.67	-
% of dominant lethals	-8.33	-

Conclusions:

Interpretation of results (migrated information): negative
The test substance did not cause genetic disorders in mice.

Executive summary:

A group of 7 male mice was fed a diet containing 0.6% test substance for 9 months. At the end of this period, the animals were each mated with two untreated females. On day 13 of pregnancy, the females were sacrificed, and the ovaries and uteri were examined. No increase in dominant lethal induction was seen as compared to controls. The test substance does not cause genetic disorders.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vivo:

A series of in vivo mutagenicity studies are available. In the first study, 40 male and 40 female mice were given a single oral dose by gavage of 1122 mg/kg of the read-across substance LAB Sulfonic Acid and evaluated for chromosome aberrations. Only a single dose has been evaluated which was in the range of the acute oral LD50 value for LAB Sulfonic Acid in rats (LD50 = 1470 mg/kg). Furthermore, slight cytotoxicity has been observed after 48 hours. No statistically significant or biologically relevant increases in the number of polychromatic erythrocytes with micronuclei were observed; therefore the test material is considered negative for cytogenicity.

In an in vivo mammalian chromosome aberration study on LAS (read across) by Inoue et al. 1976, groups of male mice were given doses of 200, 400, or 800 mg LAS/kg. This is about half the acute oral LD50 of 1655 mg/kg, as cited by the authors of the study. Mice were sacrificed at 6, 24, and 48 hrs, three of the mice from each dosage group were sacrificed, and bone marrow cells from the femurs collected and examined for chromosome aberrations. In addition, one group of mice was exposed daily for 5 consecutive days. Additional groups of mice were exposed to commercial detergents containing 19% or 17.1% of LAS. None of the treatment groups showed any significant increase in chromosome aberrations as compared to negative controls while the positive control, Mitomycin C, clearly showed an increase in chromosomal aberration frequency. Therefore, the read-across substance was not considered clastogenic in this assay.

A second chromosomal aberration study on LAS (read across) was conducted by Masubuchi et al. 1976. In this study, groups of five male mice or five male rats were fed diets containing 0.9% LAS for 9 months (1125 mg/kg bw/d for mice, 405 mg/kg bw/d for rats). At the end of this period, the animals were sacrificed, and the bone marrow cells examined for chromosome aberrations. No increase in chromosome aberrations was seen as compared to negative controls in either species but no positive controls have been included in this assay. The read-across substance LAS was not clastogenic in this assay.

These same authors (Masubuchi et al. 1976) also conducted a dominant lethal study in mice. A group of seven male mice were fed a diet containing 0.6% of the read-across substance LAS for 9 months (750 mg/kg bw/d). At the end of this period they were each mated with two untreated females. Females were sacrificed on day 13 of gestation for examination of ovaries and uteri. No evidence of dominant lethal mutations was observed as compared to the controls.