1-chloro-2,3-epoxypropane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Epichlorohydrin has been reported to be positive in a number of in vitro and in vivo mutagenicity assays.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was conducted prior to GLP and test guidelines, but sufficient data is available for interpretation of results

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

Only two doses were conducted and test was not conducted with metabolic activation.

GLP compliance:

no

Type of assay:

mammalian cell gene mutation assay

Target gene:

HPRT gene

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

No addtional information provided.

Additional strain / cell type characteristics:

not specified

Metabolic activation:

without

Test concentrations with justification for top dose:

0.0, 0.5 and 1mM

Vehicle / solvent:

no data

Details on test system and experimental conditions:

Mouse lymphoma ceIls
The cells were cultured in a humidified CO, incubator (5% CO,) at 37C in standard medium, Ham's F10 modified by the omission of hypoxanthine and
thymidine, and supplemented with 15% newborn calf serum (Gibco), penicillin G (100 U/ml) and streptomycin (0.1 mg/ml). For cloning, the standard medium was supplemented with 0.4% Noble agar. To select for cells with the HGPRT-deficient phenotype, the agar medium was supplemented with the purine analog 6-thioguanine (TG, 5 ug/ml) (Knaap and Simons, 1975).

In the mutagenesis assays, cells were exposed to the compound at the appropriate concentrations, for 2 h at 37C. After treatment, cells were washed and (a) seeded for survival, 150 cells per 15 ml of agar medium per P94 petri dish (5 dishes per group), and (b) propagated in Roux bottles for several days in standard medium to allow expression of the induced mutants that had resulted from the treatment (about 10(7) cells per group). During the expression time, cell counts were made daily (coulter counter) to keep record of cell growth, and according to these, cultures were diluted. At the end of the expression time, i.e. 7 days after treatment, cells were seeded for (a) cloning efficiency, 150 cells per 15 ml of agar medium per P94 petri dish (5 dishes per group), and (b) selection of mutants, 7.5 X 10(5) cells per 15 ml of selective medium per P94 petri dish (10 dishes per group). The
mutant frequency was calculated according to the following formula:

mutant frequency = (100/cloning efficiency) x (number of mutants/number of cells seeded)

Test was conducted in duplicate.

Evaluation criteria:

No additional information provided.

Statistics:

No data.

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

not specified

Untreated negative controls validity:

valid

Positive controls validity:

not examined

Additional information on results:

At 0.5 mM, approximately 63.6% of the cells survived on day 0 while 18.1% of the cells exposed to 1.0 mM ECH survived on day 0. The induced mutant frequency was 2.0 and 4.0 x 10(5) at 0.5 and 1.0 mM, respectively. There was considerable variation is response at a specific concentration, i.e., at 0.5 mM, the induced mutant frequency was 2.8 and 1.2 x 10(5).

Epichlorohydrin was positive in L5178 mouse lymphoma cells without metabolic activation.

Conclusions:

Interpretation of results (migrated information):
positive without metabolic activation

Epichlorohydrin was positive in L5178 mouse lymphoma cells without metabolic activation.

Executive summary:

Epichlorohydrin was positive in L5178 mouse lymphoma cells without metabolic activation.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was conducted prior to GLP and test guidelines, but sufficient data is available for interpretation of results

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

results from only two strains reported. No mention of other strains being tested.

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

his operon in Salmonella typhimurium

Test concentrations with justification for top dose:

0.254, 0.635 and 2.54 umol/plate without S9 and 2.54, 6.34 and 25.4 umol/plate with S9.

Vehicle / solvent:

DMSO

Details on test system and experimental conditions:

Three aromatic epoxy resins were tested by the plate incorporatian assay with bstidine-requiring mutants of S. typhimurium. The test was carried our as described by Ames et al. The S9 mix was prepared from rat liver activated with sodium phenobarbital and containing NADP.

Epichlorohydrin (ECH) was included as positive control. Only results from epichlorhydrin are included here.

Evaluation criteria:

Not stated.

Statistics:

No information provided.

Species / strain:

S. typhimurium, other: TA100 and TA1535

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

positive with and without metabolic activation

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

Without S9, the response was elevated at the lowest dose examined, 0.254 umol/plate. With S9, the response was slightly elevated from control values at 2.54 umol/plate. At higher doses, a greater response was observed.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Without S9, the response was elevated at the lowest dose examined, 0.254 umol/plate. With S9, the response was slightly elevated from control values at 2.54 umol/plate. At higher doses, a greater response was observed.

Conclusions:

Interpretation of results (migrated information):
positive

Epichlorohydrin is a direct acting mutagen.

Executive summary:

Epichlorohydrin (ECH) is a direct acting mutagen with a positive response noted at the lowest dose tested, 0.254 umol/plate.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study was conducted prior to GLP and guidelines but sufficient data is available for the interpretation of results.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

only tested one dose level and only tested each strain without metabolic activation

GLP compliance:

no

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidene gene for all S. typhimurium strains

Test concentrations with justification for top dose:

material was tested at 1 ul/plate in strains TA98, TA100, TA1535, TA1537 and TA1538

Vehicle / solvent:

no vehicle used

Untreated negative controls:

yes

Negative solvent / vehicle controls:

no

True negative controls:

yes

Positive controls:

not specified

Remarks:

test material was not tested with a solvent or vehicle.

Details on test system and experimental conditions:

Petri plates containing minimal-glucose agar and 2.0 ml top agar mixed with 0.1 ml of histidine-requiring mutant cultures and 0.2 ml samples of the urine specimens or 1 ul epichlorohydrin were incubated at 37C for 48 hours. Results were expressed as the ratio of the number of bacterial colonies (revertants to histidine prototrophy) on the plates treated with epichlorohydrin to the number of colonies (spontaneous revertants) counted on untreated plates.

Evaluation criteria:

Results were considered to be negative if the difference in the number of induced revertants compared to the number of spontaneous revertants was less than two-fold.

Statistics:

No data.

Species / strain:

S. typhimurium, other: TA100 and TA1535

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

not applicable

Untreated negative controls validity:

valid

Positive controls validity:

not specified

Additional information on results:

Revertants (treated)/Revertants (control) were >150 for strains TA100 and TA1500 without metabolic activation. All other strains were less than 2 times greater than control values.

Remarks on result:

other: strain/cell type: TA100 and TA1535

Remarks:

Migrated from field 'Test system'.

Response in TA100 and TA1535 was >150 fold greater than control values while response in the three other strains tested, TA98, TA1537 and TA1538, was less than 2 fold greater than respective control values.

Conclusions:

Interpretation of results (migrated information):
positive without metabolic activation

Epichlorohydrin was found to be highly in in vitro tests with strains TA 1535 and TA 100, but not mutagenic in Strains TA 1537, TA 1538, and TA 98.
urine samples from workers exposed to TWA concentrations of 4 ppm or less did not show significant difference fro the negative results but the samples obtained from a group exposed to 25 ppm showed a greater than two fold increase in TA 1535.

Executive summary:

A sample of epichlorohydrin was also tested, directly, against the five S. typhimurium strains. Epichlorohydrin was found to be highly mutagenic in in vitro tests with strains TA 1535 and TA 100, but not mutagenic in strains TA 1537, TA 1538, and TA 98.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Genetic toxicity in vivo

Description of key information

Epichlorohydrin has been reported to be positive in a number of in vitro and in vivo mutagenicity assays.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study was conducted prior to GLP and test guidelines, but sufficient data is available for interpretation of results

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Principles of method if other than guideline:

Study was conducted prior to OECD guidelines but essentially followed guideline

GLP compliance:

no

Type of assay:

chromosome aberration assay

Species:

mouse

Strain:

ICR

Sex:

female

Details on test animals or test system and environmental conditions:

Female ICR mice, 8-10 weeks of age, weighing approximately 32-35 g were used.

Route of administration:

oral: gavage

Vehicle:

DMSO obtained from Merck.

Details on exposure:

Test material was administered via oral gavage to mice for a single application (5, 20, 40 and 100 mg/kg) or for 5 repeated doses over 5 days or for 5 repeated doses over 7 days (test material was administered on days 1, 2, 5, 6 and 7) (20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

In addition, the test material was administered intraperitoneally to mice for a single dose (1, 3, 5, 10, 20 and 40 mg/kg) or for 5 repeated doses over 5 days (10 mg/kg) or for 5 repeated doses over 7 days (test material administered on days 1, 2, 5, 6 and 7) (5, 10 or 20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

Duration of treatment / exposure:

Test material was administered via oral gavage to mice for a single application (5, 20, 40 and 100 mg/kg) or for 5 repeated doses over 5 days or for 5 repeated doses over 7 days (test material was administered on days 1, 2, 5, 6 and 7) (20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

In addition, the test material was administered intraperitoneally to mice for a single dose (1, 3, 5, 10, 20 and 40 mg/kg) or for 5 repeated doses over 5 days (10 mg/kg) or for 5 repeated doses over 7 days (test material administered on days 1, 2, 5, 6 and 7) (5, 10 or 20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

Frequency of treatment:

Test material was administered via oral gavage to mice for a single application (5, 20, 40 and 100 mg/kg) or for 5 repeated doses over 5 days or for 5 repeated doses over 7 days (test material was administered on days 1, 2, 5, 6 and 7) (20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

In addition, the test material was administered intraperitoneally to mice for a single dose (1, 3, 5, 10, 20 and 40 mg/kg) or for 5 repeated doses over 5 days (10 mg/kg) or for 5 repeated doses over 7 days (test material administered on days 1, 2, 5, 6 and 7) (5, 10 or 20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

Post exposure period:

Test material was administered via oral gavage to mice for a single application (5, 20, 40 and 100 mg/kg) or for 5 repeated doses over 5 days or for 5 repeated doses over 7 days (test material was administered on days 1, 2, 5, 6 and 7) (20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

In addition, the test material was administered intraperitoneally to mice for a single dose (1, 3, 5, 10, 20 and 40 mg/kg) or for 5 repeated doses over 5 days (10 mg/kg) or for 5 repeated doses over 7 days (test material administered on days 1, 2, 5, 6 and 7) (5, 10 or 20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

Remarks:

Doses / Concentrations:
Oral gavage: 5, 20, 40 or 100 mg/kg (single application), 20 mg/kg for 5 applications over 5 or 7 days. IP: 1, 3, 5, 10, 20 or 40 mg/kg (single application), 20 mg/kg (5 applications over 5 days) or 5, 10 or 20 mg/kg (5 applications over 7 days).
Basis:
no data

No. of animals per sex per dose:

no data

Control animals:

yes, concurrent vehicle

Positive control(s):

no data

Tissues and cell types examined:

The mouse bone marrow was prepared according to the modification of Tjino and Whang's method (Goetz et al., 1975). 250 metaphases were analyzed in each group. Gaps, breaks and exchanges were evaluated. Cells bearing some of these changes were considered abnormal. Cells with more than 10 aberrations were counted separately (Adler et al., 1971, Nichols et al., 1972).

Adler, I.D., Ramarao, G., and Epstein, S.S. (1971). In vivo cytogenetic effects of trimethylphosphate and of TEPA on bone marrow cells of male rats. Mutation Research 13:263-273.

Goetz, P., Sram, R.J., and Dohnalova, J. (1975). Relationship between experimental results in mammals and man. I. Cytogenetic analysis of bone marrow injury induced by a single dose of cyclophosphamide. Mutation Research 31:247-254.

Nichols, W.W., Moorhead, P. and Brewen, G. (1972)., Chromosome methodologies in mutation testing. Toxicol. Appl. Pharmacol. 22:269-275.

Details of tissue and slide preparation:

No additional information available.

Evaluation criteria:

Gaps, breaks and exchanges were evaluated. Cells bearing some of these changes were considered abnormal.

Statistics:

Statistical evaluation was apparently not conducted.

Sex:

female

Genotoxicity:

positive

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not specified

Positive controls validity:

not specified

Additional information on results:

The time-effect relationship was evaluated after applying an i.p. injection of 50 mg ECHH/kg and after application of p.0.100mg ECHH/kg. Since no difference was found in the frequency of abnormal cells after i.p. application in the 6 and 24 h groups and in all the groups after p.o. application, the dose-effect relationship and the routes of applications were compared always 24 h after the administration of ECHH.

Dose-effect relationship expressed in the frequency changes of abnormal cells was found after a single ip. application of a dose ranging from 1-20 mg ECHH/kg and after p.0. application especially in, a range of 5-20 mg ECHH/kg. Dose-effect relationship was found also after repeated i.p. application of 5 doses ranging between 5-20 mg ECHH/kg. The comparative evaluation of thc effect of the total dose applied in a single or repeated scheme, showed that the same total dose - if applied in repeated doses - induced both a higher frequency of abnormal cells and a higher frequency of breaks per cell. As to the comparison of the routes of administration at the same dose, the intraperitoneally applied ECHH induced approx. twice as many chromasomal abnormalities than ECBH applied perorally.

ECHH induced mostly breaks and exchanges. The cells bearing more than 10 aberrations were found quite exceptionally.

Dose-effect relationship expressed in the frequency changes of abnormal cells was found after a single ip. application of a dose ranging from 1-20 mg ECHH/kg and after p.o. application especially in, a range of 5-20 mg ECHH/kg.

Conclusions:

Interpretation of results (migrated information): positive
This cytogenetic study showed a positive response following oral or ip administration of epichlorohydrin.

Executive summary:

Epichlorohydrin (ECH) is one of the more commercially important aliphatic epoxides used extensively as an industrial intermediate, a laboratory reagent, and as an insecticide. It is a volatile, colourless liquid with an ethereal odour. This cytogenetic study showed a positive response following oral or ip administration of epichlorohydrin.

Reference 2

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study was conducted prior to GLP and guidelines but sufficient data is available for the interpretation of results.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

GLP compliance:

no

Type of assay:

chromosome aberration assay

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

Groups of 10 male and 10 female Fischer 344 rats were exposed. by inhalation to 0, 5, 25 or 50 ppm of epichlorohydrin in the air for 6 hours/day, 5 days/week for 4 weeks. There were 26 and 27 days of exposure for males and females, respectively, during this interval. The animals were individually caged and kept in the exposure chamber during both the exposure and nonexposure intervals. Food was removed during the exposure periods, but was otherwise freely available. Water, via an automatic water system, remained available at all times. These animals were exposed simultaneously
with those in the 90-day subchronic study. Therefore, additional details of the exposure generation and monitoring are presented in that report.

Route of administration:

inhalation: vapour

Vehicle:

not applicable

Details on exposure:

These animals were exposed simultaneously with those in the 90-day subchronic study. Therefore, additional details of the exposure generation and monitoring are presented in that report.

Duration of treatment / exposure:

Groups of 10 male and 10 female Fischer 344 rats were exposed. by inhalation to 0, 5, 25 or 50 ppm of epichlorohydrin in the air for 6 hours/day, 5 days/week for 4 weeks. There were 26 and 27 days of exposure for males and females, respectively, during this interval. These animals were exposed simultaneously with those in the 90-day subchronic study. Therefore, additional details of the exposure generation and monitoring are presented in that report.

Frequency of treatment:

Groups of 10 male and 10 female Fischer 344 rats were exposed. by inhalation to 0, 5, 25 or 50 ppm of epichlorohydrin in the air for 6 hours/day, 5 days/week for 4 weeks. There were 26 and 27 days of exposure for males and females, respectively, during this interval.

Post exposure period:

On the day following the last exposure (approximately 18 hours), the rats were injected intraperitoneally with colchicine four hours prior to sacrifice, and the bone marrow cells were processed.

No. of animals per sex per dose:

10 male and 10 female Fischer 344 rats/dose level

Positive control(s):

no positive control

Tissues and cell types examined:

Bone marrow cells were processed. Slides were coded, randomized, and evaluated by three accredited medical technologists. The methods used for the scoring and analysis followed the criteria set by Buckton and Evans (1973). The mitotic index was determined as the percentage of cells in metaphase, based on the observation of 500 cells.

Buckton, K. E. and H. J. Evans. Methods for the Analysis of human chromosome aberrations. World Health Organization, Geneva (1973).

Details of tissue and slide preparation:

Bone marrow cells were processed. Slides were coded, randomized, and evaluated by three accredited medical technologists. The methods used for the scoring and analysis followed the criteria set by Buckton and Evans (1973). The mitotic index was determined as the percentage of cells in metaphase, based on the observation of 500 cells.

Buckton, K. E. and H. J. Evans. Methods for the Analysis of human chromosome aberrations. World Health Organization, Geneva (1973).

Evaluation criteria:

Authors followed the criteria set by Buckton and Evans (1973).

Buckton, K. E. and H. J. Evans. Methods for the Analysis of human chromosome aberrations. World Health Organization, Geneva (1973).

Statistics:

The results of the abnormal cells were analyzed using Fisher's exact probability test (Siegel, 1956) with the animal as the unit. The data were further analyzed using the Wilcoxon test as modified by Haseman and Hoe1 (1974) to take into account the multiple abnormalities in some animals. Mitotic index was analyzed (Steel and Torrie ) using a one-way analysis of variance.

Haseman, J. K. and D. G. Hoel. (1974). Tables of Gehan's generalized Wilcoxon test with fixed point sensoring. J. Stat. Comp. and Simulation 3: 117-135.

Seigel, S. (1956). Nonparamentric Statistics for the Behavioral Sciences. McGraw-Hill Book Company, Inc., New York, New York, pp. 96-104.

Steel, R. G. and H. H. Torrie. (1960). Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc. New York.

Sex:

male/female

Genotoxicity:

ambiguous

Toxicity:

not specified

Vehicle controls validity:

not applicable

Negative controls validity:

not specified

Positive controls validity:

other: No positve control

Additional information on results:

Two groups of samples--from the female animals exposed to 5 and 25 ppm--were inadvertantly destroyed during centrifugation of the cell preparations and were not available for evaluation. Slides of sufficient quality to score 200 cells per animal were obtained from 36 of the 40 male rats and from 14 of the 20 females. Slides from the remaining animals were not scorable. Mitotic indices on 500 cells from the females were not significantly different by analysis of variance between the control and exposed groups (p=0.645). The clustering of unscorable slides from the exposed females was thus probably not a manifestation of cytotoxicity. The frequencies of chromosomal aberrations overall were quite low. For the 5 ppm group of males the percentage of abnormal cells was less than half that of the unexposed males. While the group findings for males at 25 and 50 ppm were twofold higher than the controls, there was no consistent dose-response effect. There was fewer than one abnormal cell per animal for all groups, with no chromosome breaks or markers in any group of the males. The overall rarity of chromosomal aberrations makes it difficult to determine if the observations in the 25 and 50 ppm male groups were associated with exposure, or were rather inherent fluctuations, as seen in the results from the 5 ppm group when compared with the unexposed controls. Results of statistical analyses of the data from the males were as follows. The number of animals with aberrations was 4/18 for the pooled control and 5 ppm exposed groups, and 8/18 for the pooled 25 ppm and 50 ppm groups. These proportions were not significantly different by Fisher's test (p>0.10). Haseman's test, the most appropriate way to test multiple events in animals, had a calculated p value between 0.05 and 0.1. If the data are analyzed with each dosage group considered separately, there are no significant differences by any method. Thus all of the statistical tests confirmed that the differences in the males were not significant at the 5% level. However, there was a trend toward a higher total number of abnormal cells in the 25 and 50 ppm exposure groups of males. In contrast to the results of the males, there was no difference between the frequency of abnormal cells in the 50 ppm exposed females compared to the unexposed control group.

Results of statistical analyses of the data from the males were as follows. The number of animals with aberrations was 4/18 for the pooled control and 5 ppm exposed groups, and 8/18 for the pooled 25 ppm and 50 ppm groups. These proportions were not significantly different by Fisher's test (p>0.10). Haseman's test, the most appropriate way to test multiple events in animals, had a calculated p value between 0.05 and 0.1. If the data are analyzed with each dosage group considered separately, there are no significant differences by any method. Thus all of the statistical tests confirmed that the differences in the males were not significant at the 5% level. However, there was a trend toward a higher total number of abnormal cells in the 25 and 50 ppm exposure groups of males. In contrast to the results of the males, there was no difference between the frequency of abnormal cells in the 50 ppm exposed females compared to the unexposed control group.

Conclusions:

Interpretation of results (migrated information): ambiguous
There was no ovserved increase in the frequency of chromosomal abberations in females and no significant difference in the frequency of chromosomal abberations in males.

Executive summary:

Groups of 10 male and 10 female Fischer 344 rats each were exposed to 0, 5, 25, or 50 ppm of epichlorohydrin in air for 6 hours/day, 5 days/week for 4 weeks. This was part of a larger subchronic study. In most cases, 200 cells were scored per animal for various chromosomal aberrations. The frequency of aberrations found for all groups was quite low. While the 25 and 50 ppm male groups showed a doubling over controls, there was no consistent dose-response effect observed in these males. In addition, the number of chromosomal aberrations observed in the 5 ppm exposed males was decreased to a greater extent than were the increases observed in either 25 or 50 ppm males as compared to their controls. Statistical analysis by Fisher's exact probability test, a modified Wilcoxon test, and analysis of variance indicated that the differences in the males were not significant at the 5% level. There was no observed increase in the frequency of chromosomal aberrations found in the female rats exposed to 50 ppm epichlorohydrin as compared to their controls.

The results of this study indicate that exposure of rats to epichlorohydrin by the inhalation route does not produce chromosomal aberrations at the same rate as reported for comparable doses administered orally or intraperitoneally to mice.

The bone marrow cytogenetic study in Fischer 344 male and female rats following 30 days of inhalation exposure to epichlorohydrin (HET-K-001710-(13)) was a supplement to a 90- day subchronic study (HET-K-001710-(11)). These studies were sponsored by the Manufacturing Chemists Association.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (positive)

Additional information

Epichlorohydrin has been reported to be positive in the following in vitro assays: Ames test without metabolic activation, in rat hepatocytes (UDS) and mouse lymphoma cells (HGPRT) and in the following in vivo assay in Drosophila (SRL). In other tests, including Drosophila (SRL), mouse dominant lethal assay and human lymphocyte DNA adduct assay, the results were negative with epichlorohydrin.

Bacterial reverse mutation assay

In an Ames test conducted with Salmonella typhimurium strains TA100 and TA1535, Epichlorohydrin (ECH) is a direct acting mutagen with a positive response noted at the lowest dose tested, 0.254 µmol/plate.

 

Epichlorohydrin was found to be highly mutagenic in in vitro tests with strains TA 1535 and TA 100, but not mutagenic in Strains TA 1537, TA 1538, and TA 98. The response in TA100 and TA1535 was >150 fold greater than control values, the while response in the three other strains tested, TA98, TA1537 and TA1538, was less than 2fold greater than respective control values.

 

in vitro gene mutation study in mammalian cells

A gene mutation study in mammalian cells was conducted with mouse lymphoma L5178Y cells. Cells were exposed to 0.0 (control), 0.5 and 1 mM Epichlorohydrin without metabolic activation.

At 0.5 mM, approximately 63.6% of the cells survived on day 0 while 18.1% of the cells exposed to 1.0 mM ECH survived on day 0. The induced mutant frequency was 2.0 and 4.0E05 at 0.5 and 1.0 mM, respectively. There was considerable variation is response at a specific concentration, i.e., at 0.5 mM, the induced mutant frequency was 2.8 and 1.2E05.

Epichlorohydrin was positive in L5178 mouse lymphoma cells without metabolic activation.

 

in vivo mammalian bone marrow chromosome aberration studies

Epichlorohydrin was administered via oral gavage to female ICR mice for a single application (5, 20, 40 and 100 mg/kg) or for 5 repeated doses over 5 days or for 5 repeated doses over 7 days (test material was administered on days 1, 2, 5, 6 and 7) (20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

In addition, the test material was administered intraperitoneally to mice for a single dose (1, 3, 5, 10, 20 and 40 mg/kg) or for 5 repeated doses over 5 days (10 mg/kg) or for 5 repeated doses over 7 days (test material administered on days 1, 2, 5, 6 and 7) (5, 10 or 20 mg/kg). Mice were sacrificed 6, 24 or 48 hr after a single dose or 6 hrs after the administration of the final dose in the scheme of repeated applications.

Dose-effect relationship expressed in the frequency changes of abnormal cells was found after a single i.p. application of a dose ranging from 1-20 mg/kg and after p.0. application especially in, a range of 5-20 mg/kg. Dose-effect relationship was found also after repeated i.p. application of 5 doses ranging between 5-20 mg/kg. The comparative evaluation of the effect of the total dose applied in a single or repeated scheme, showed that the same total dose - if applied in repeated doses - induced both a higher frequency of abnormal cells and a higher frequency of breaks per cell. As to the comparison of the routes of administration at the same dose, the intraperitoneally applied Epichlorohydrin induced approx. twice as many chromosomal abnormalities than Epichlorohydrin applied perorally. Epichlorohydrin induced mostly breaks and exchanges. The cells bearing more than 10 aberrations were found quite exceptionally.

Administration of epichlorohydrin via oral or ip routes for a single or multiple exposure resulted in an increase in the number of breaks/abnormal cell or number of gaps/abnormal cell.

 

Groups of 10 male and 10 female Fischer 344 rats each were exposed to 0, 5, 25, or 50 ppm of epichlorohydrin in air for 6 hours/day, 5 days/week for 4 weeks. This was part of a larger subchronic study. In most cases, 200 cells were scored per animal for various chromosomal aberrations. The frequency of aberrations found for all groups was quite low. While the 25 and 50 ppm male groups showed a doubling over controls, there was no consistent dose-response effect observed in these males. In addition, the number of chromosomal aberrations observed in the 5 ppm exposed males was decreased to a greater extent than were the increases observed in either 25 or 50 ppm males as compared to their controls. Statistical analysis by Fisher's exact probability test, a modified Wilcoxon test, and analysis of variance indicated that the differences in the males were not significant at the 5% level. There was no observed increase in the frequency of chromosomal aberrations found in the female rats exposed to 50 ppm epichlorohydrin as compared to their controls.

The results of this study indicate that exposure of rats to epichlorohydrin by the inhalation route does not produce chromosomal aberrations at the same rate as reported for comparable doses administered orally or intraperitoneally to mice.

Justification for classification or non-classification

Because epichlorohydrin has not shown evidence of germ cell mutagenicity, no classification was considered.