N,N-dimethylformamide

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

chromosome aberration

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable well-documented study which meets basic scientific principles.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

2 animals/sex were used instead of 5.

GLP compliance:

no

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

no data

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: the test material was applied to abraded skin of animals.

Duration of exposure:

24 hours

Doses:

3160 mg/kg bw

No. of animals per sex per dose:

2

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: Day 2, 4, 8, 11 and 15 observation of exposure sites and scoring; 2 and 4 hours post-dosing and daily thereafter observation for mortality and toxic effects
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, mortality, exposure sites (scored for erythema and edema)

Statistics:

no data

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 3 160 mg/kg bw

Based on:

test mat.

Mortality:

1 male animal died on day 4 of the study.

Clinical signs:

other: No substance-related clinical findings were reported.

Gross pathology:

Gross necropsy revealed no substance-related effect.

Other findings:

No signs of systemic toxicity or percutaneous absorption were observed.

Interpretation of results:

other:

Remarks:

EU GHS criteria not met

Conclusions:

No substance-related findings were reported in the study.
LD50for both sexes is higher than 3160 mg/kg bw/day.

Executive summary:

Study design

This non-GLP study was performed according to OECD TG No. 402 Acute Dermal Toxicity. In the study, 2 male and 2 female Sprague-Dawley rats were treated with the undiluted test substance at a dose level of 3160 mg/kg under occlusive conditions on abraded skin for 24h. On days 2, 4, 8, 11 and 15 exposure sites were examined and scored for erythema and edema on a graded scale of 0 to 4.
Each animal was observed for mortality and toxic effects 2 and 4 hours post-dosing and daily thereafter.

Results

In the 14 -days post-observation period, 1/4 animals died (one male animal) on day 4 of the study, however, gross necropsy revealed no substance related effect. Among the remaining animals, no signs of systemic toxicity or percutaneous absorption were observed.

Conclusion

No substance-related findings were reported in the study. LD₅₀for both sexes is higher than 3160 mg/kg bw/day.

Cross-reference 2

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

No data on a OECD compliance

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Principles of method if other than guideline:

- Short description of test conditions: Instillation of 0.1 mL of neat test substance into one eye of 6 New Zealand rabbits without rinsing. The untreated eye served as control. Readings were done 1, 4, 24, 48, 72 hours and 4, 7, 10, and 13 days after application.
- Parameters analysed / observed: Scoring of ocular lesions was done according to Draize et.al. (1944).

GLP compliance:

no

Remarks:

The study was performed prior to the adoption of GLP compliance.

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

No information given

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated eye

Amount / concentration applied:

undiluted

Duration of treatment / exposure:

single dose

Observation period (in vivo):

13 days

Number of animals or in vitro replicates:

6

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Eyes were not rinsed after treatment.

SCORING SYSTEM: according to Draize et.al. (1944)

Irritation parameter:

other: primary irritation index

Basis:

mean

Time point:

other: 1h

Score:

50.8

Max. score:

110

Reversibility:

fully reversible within: 48 h

Irritation parameter:

other: primary irritation index

Basis:

mean

Time point:

72 h

Score:

35.8

Max. score:

110

Reversibility:

fully reversible within: 48 h

Irritation parameter:

other: primary irritation index

Basis:

mean

Time point:

other: day 4

Score:

35

Max. score:

110

Reversibility:

fully reversible within: 48 h

Irritation parameter:

other: primary irritation index

Basis:

mean

Time point:

other: day 13

Score:

3.3

Max. score:

110

Reversibility:

fully reversible within: 48 h

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: no details given

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: no details given

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: no details given

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: no details given

Other effects:

Other observations: Primary irritation index was 50.8 after 1 h decreasing to 35.8 after 72 h and 35.0 on day 4 decreasing to 3.3 on day 13 (max. = 110). All animals in the present study showed large blisters on the inside of upper and lower lids at the 1 and 4 hour readings. Blisters decreased in size at the 24 hour reading and they were gone at 48 hours. According to the authors, the test substance was classified as severely irritating to the rabbit eyes when applied without rinsing.

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

Classification: irritating

Executive summary:

Study design

This non-GLP in vivo study was conducted comparable to OECD TG 405. In the present study neat DMF of 0.1 mL was instilled into one eye of 6 New Zealand white rabbits without rinsing. The untreated eye served as control. Readings were performed 1 h, 4 h, 24 h, 48 h, 72 h, 4 d, 7 d, 10 d and 13 d after application. Scoring of ocular lesions was done according to the method of Draize et al. (1944).

Results

Primary irritation index was 50.8 after 1 h decreasing to 35.8 after 72 h and 35.0 on day 4 decreasing to 3.3 on day 13 (max. = 110). All animals in the present study showed large blisters on the inside of upper and lower lids at the 1 and 4 hour readings. Blisters decreased in size at the 24 hour reading and they were gone at 48 hours. According to the authors, the test substance was classified as severely irritating to the rabbit eyes when applied without rinsing.

Conclusion

Classification: irritating to eyes

Cross-reference 3

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: no data on GLP compliance

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

According to FDA: "Guidelines for Reproduction Studies for Safety Evaluation of Drugs for Human Use", Segment II

GLP compliance:

not specified

Species:

rat

Strain:

Sprague-Dawley

Route of administration:

inhalation

Duration of treatment / exposure:

on days 6-15 of gestation

Frequency of treatment:

6 h/day

Dose / conc.:

30 ppm

Remarks:

ca. 0.09 mg/L

Dose / conc.:

300 ppm

Remarks:

ca. 0.91 mg/L

Control animals:

yes

Details on study design:

Sex: female
Duration of test: until day 21 of gestation

Clinical signs:

no effects observed

Description (incidence and severity):

There were no substance-related effects on the dams of the 30 ppm group. In the 300 ppm group the dams showed a significantly lower weight gain during the treatment period (gestation day 6 - 15) when compared to the control group (39 g in comparison to 50 g). From day 15 through 21 of gestation the animals recovered and weight gain was comparable to that of the concurrent negative control group.

Mortality:

no mortality observed

Description (incidence):

All 21 female rats each of the negative and the two DMF-treated groups survived the testing period.
In the positive control group two animals died, one on day 11 and one on day 6 of gestation. According to the authors, these deaths were not related to ASA administration but assumed to be due to dosing accidents because of the lung lesions observed in these animals.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There were no substance-related effects on the dams of the 30 ppm group.
In the 300 ppm group the dams showed a significantly lower weight gain during the treatment period (gestation day 6 - 15) when compared to the control group (39 g in comparison to 50 g).
From day 15 through 21 of gestation the animals recovered and weight gain was comparable to that of the concurrent negative control group.

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Gross pathological findings:

no effects observed

Description (incidence and severity):

At necropsy, there were no substance-related findings.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Number of abortions:

not specified

Pre- and post-implantation loss:

effects observed, treatment-related

Description (incidence and severity):

In the 30 ppm group a significantly lower mean number of implantations and fetuses was seen in comparison to the negative control group (12.7 versus 14.2 mean implantations/female and 12.0 versus 13.7 live fetuses/female, respectively). The number of corpora lutea/female was slightly lower in the 30 ppm group than that of the negative controls (14.6 versus 15.3). These findings were not seen in the 300 ppm females.

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Description (incidence and severity):

The mean number of resorptions was unaltered by DMF exposure (0.5, 0.8 and 0.5 in the negative control, the 30 and the 300 ppm DMF group, respectively), but the number of dams with 2 or more resorptions (early and late) was highest in the 30 ppm group (1/21 in the negative control, 4/21 in the 30 ppm DMF and 2/21 in the 300 ppm DMF group, respectively). According to the authors the reduction in the number of fetuses at 30 ppm is regarded as an unexplainable, but not DMF-related decrease in ovulation and implantation rates. The number of females with one or more resorptions was within the ranges seen in control females. The statistically significantly decrease in implantation efficiency in the 30 ppm group in comparison to the negative control (87.3 % versus 92.5 %) was, according to the authors, in part attributable to a single female in this group that had an unusually low number of implants and high number of corpora lutea.

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

With respect to reproductive effects, there was no effect on pregnancy rates (100 %, 94.7 %, 100 % and 100 % in the negative control, the positive control and the 30 ppm and 300 ppm DMF group, respectively).

Other effects:

no effects observed

Dose descriptor:

NOAEL

Effect level:

ca. 0.09 mg/L air

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Remarks on result:

other: = 30 ppm

Remarks:

Maternal and fetal toxicity were seen at 300 ppm.

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

A reduction in mean fetal weight, but not length was observed in fetuses from dams of the 300 ppm groups (5.3 g versus 5.5 g in the negative control). This was not seen at 30 ppm.

Reduction in number of live offspring:

effects observed, treatment-related

Description (incidence and severity):

In the 30 ppm group a significantly lower mean number of fetuses was seen in comparison to the negative control group (12.0 versus 13.7 live fetuses/female, respectively).

Changes in sex ratio:

not specified

Changes in litter size and weights:

effects observed, treatment-related

Description (incidence and severity):

In the 30 ppm group a significantly lower mean number of fetuses was seen in comparison to the negative control group (12.0 versus 13.7 live fetuses/female, respectively).

Changes in postnatal survival:

not specified

External malformations:

not specified

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

The incidence of fetuses with ossification variations was significantly higher in the 300 ppm DMF group when compared to the negative control (75.0 % versus 60.2 %), however the incidence of litters containing fetuses with ossification variations was comparable to the negative control group. Soft tissue and skeletal malformations were comparable between the negative control and the DMF-treated groups.

Visceral malformations:

no effects observed

Description (incidence and severity):

Soft tissue and skeletal malformations were comparable between the negative control and the DMF-treated groups.
Isolated and not dose-related findings of soft tissue malformations were seen in one fetus of the 30 ppm group (diaphragmatic hernia) and in two fetuses out of one litter in the 300 ppm group (vacuoles in the lens of the eye).

Other effects:

no effects observed

Dose descriptor:

NOAEL

Effect level:

ca. 0.91 mg/L air

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Remarks on result:

other: = 30 ppm

Remarks:

Materal and fetal toxicity was observed at 300 ppm

Abnormalities:

not specified

Developmental effects observed:

not specified

All 21 female rats each of the negative and the two DMF-treated groups survived the testing period. In the positive control group two animals died, one on day 11 and one on day 6 of gestation. According to the authors, these deaths were not related to ASA administration but assumed to be due to dosing accidents because of the lung lesions observed in these animals. There were no substance-related effects on the dams of the 30 ppm group. In the 300 ppm group the dams showed a significantly lower weight gain during the treatment period (gestation day 6 - 15) when compared to the control group (39 g in comparison to 50 g). From day 15 through 21 of gestation the animals recovered and weight gain was comparable to that of the concurrent negative control group.

At necropsy, there were no substance-related findings. With respect to reproductive effects, there was no effect on pregnancy rates (100 %, 94.7 %, 100 % and 100 % in the negative control, the positive control and the 30 ppm and 300 ppm DMF group, respectively) but in the 30 ppm group a significantly lower mean number of implantations and fetuses was seen in comparison to the negative control group (12.7 versus 14.2 mean implantations/female and 12.0 versus 13.7 live fetuses/female, respectively). The number of corpora lutea/female was slightly lower in the 30 ppm group than that of the negative controls (14.6 versus 15.3). These findings were not seen in the 300 ppm females. The mean number of resorptions was unaltered by DMF exposure (0.5, 0.8 and 0.5 in the negative control, the 30 and the 300 ppm DMF group, respectively), but the number of dams with 2 or more resorptions (early and late) was highest in the 30 ppm group (1/21 in the negative control, 4/21 in the 30 ppm DMF and 2/21 in the 300 ppm DMF group, respectively). According to the authors the reduction in the number of fetuses at 30 ppm is regarded as an unexplainable, but not DMF-related decrease in ovulation and implantation rates. The number of females with one or more resorptions was within the ranges seen in control females. The statistically significantly decrease in implantation efficiency in the 30 ppm group in comparison to the negative control (87.3 % versus 92.5 %) was, according to the authors, in part attributable to a single female in this group that had an unusually low number of implants and high number of corpora lutea.
A reduction in mean fetal weight, but not length was observed in fetuses from dams of the 300 ppm groups (5.3 g versus 5.5 g in the negative control). This was not seen at 30 ppm.
The incidence of fetuses with ossification variations was significantly higher in the 300 ppm DMF group when compared to the negative control (75.0 % versus 60.2 %), however the incidence of litters containing fetuses with ossification variations was comparable to the negative control group. Soft tissue and skeletal malformations were comparable between the negative control and the DMF-treated groups.

Isolated and not dose-related findings of soft tissue malformations were seen in one fetus of the 30 ppm group (diaphragmatic hernia) and in two fetuses out of one litter in the 300 ppm group (vacuoles in the lens of the eye).

Positive control females gained less body weight during the dosing and post-treatment period when compared to negative control values and had fewer fetuses and higher incidence of resorptions. The fetuses were smaller, had a higher number of ossification variations and an increased incidence of external, soft tissue and skeletal malformations. A dose of 250 mg/kg/d of ASA was considered to be embryotoxic and teratogenic.

Thus, in the present study maternal and fetal toxicity were seen at 300 ppm.
The NOAEC for maternal toxicity and fetotoxicity was determined to be 30 ppm.
According to the authors, these findings suggested that the test substance was not embryotoxic or teratogenic at 30 ppm and non-teratogenic even at a maternal toxic dose level of 300 ppm DMF.

Conclusions:

The NOAEC for maternal toxicity and fetotoxicity was determined to be 30 ppm.

Executive summary:

The test substance was administered to groups of 21 pregnant rats. The female rats were 12 to 14 weeks of age at the beginning of the study. Overnight mating (1:1) was done and vaginal smears were prepared. When sperm and/or vaginal plug were observed the day was defined as day 0 of gestation. Two control groups were used: one chamber-air exposed (negative control) and one group given 250 mg/kg/d of acetylsalicylic acid (ASA) suspended in 0.5 % Methocel by gavage (positive control) on gestation days 6-15. Females were sacrificed on gestation day 21. Fetuses were evaluated for external, soft tissue and skeletal malformations.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1978

Report date:

1978

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: Evaluation of mutagenicity in test system after premating DMF-exposure.
- Short description of test conditions: Male rats were exposed to DMF-vapour. At least 2 h after the last exposure, two untreated virgin females were placed into each male's cage for 7 days. This mating procedure continued for six consecutive weeks. Females were sacrificed after a gestation period of 11-18 days. At completion of the study the males were sacrificed and necropsy was performed.
- Parameters analysed / observed: During the mating intervals: clinical signs, mortality, body weight. At completion of the study: Pregnancy rates and implantation,iImplantation efficiency, fetal death, uterine implants, histopathology of reproductive organs

GLP compliance:

no

Type of assay:

rodent dominant lethal assay

Test material

Test material information

Constituent 1

Reference substance name:

N,N-dimethylformamide

EC Number:

200-679-5

EC Name:

N,N-dimethylformamide

Cas Number:

68-12-2

Molecular formula:

C3H7NO

IUPAC Name:

N,N-dimethylformamide

Details on test material:

N,N-dimethylformamide; no data on purity of the compound

Test animals

Species:

rat

Strain:

other: Sprague-Dawley (CRCD)

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Males used were about 8 weeks and females about 6 weeks of age

Administration / exposure

Route of administration:

inhalation

Details on exposure:

no details given

Duration of treatment / exposure:

5 d

Frequency of treatment:

6 h/d

Post exposure period:

six week post-treatment period

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

30 ppm

Remarks:

ca. 0.09 mg/L

Doses / concentrations 2

Dose / conc.:

300 ppm

Remarks:

ca. 0.91 mg/L

No. of animals per sex per dose:

Each group (two DMF-exposed) and the control groups contained 10 proven fertile male rats. Number of female animals not specified.

Control animals:

yes, concurrent no treatment

Positive control(s):

triethylenemelamine saline solution
- Justification for choice of positive control(s):
- Route of administration: i.p.
- Doses / concentrations: 0.5 mg/kg and a volume of 1 mL/kg administered once two hours prior to mating

Examinations

Tissues and cell types examined:

At completion of the study the males were sacrificed and necropsy was performed. The following tissues of 5 males/group were preserved: seminal vesicles, epididymides, testes, prostate and from all males any abnormal lesions or tissue masses. Histopathological examination was carried out on seminal vesicles, epididymides, testes and prostate.
Regarding in-life observations, please see 'Any other information on materials and methods'

Details of tissue and slide preparation:

10 fertile male rats/dose group or control group

Evaluation criteria:

no details given

Statistics:

no details given

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Additional information on results:

For more details see: 'Any other information'

Any other information on results incl. tables

All male animals survived until termination of the study. During treatment and during the six week post-treatment mating period all animals were unremarkable. Mean body weights for males exposed to 30 and 300 ppm DMF were slightly lower than the negative control already during pre-treatment. This trend persisted during treatment and post-treatment. Body weight gain during the post-treatment mating period was slightly lower than negative control for the males exposed to 300 ppm DMF.

Pregnancy rates and implantation efficiency values of females mated to males exposed to DMF were considered comparable to the negative control throughout the post-treatment period. In contrast, pregnancy rates for the females mated to males of the positive control were lower than the negative control at mating weeks 2, 3 and 4, only at week 4 this difference was statistically significant.

Implantation efficiency values were significantly lower at weeks 2-6. Early fetal death data were significantly increased during the entire post-treatment mating period. Fetal death data for the DMF-treated groups were slightly higher than negative control at week 2 for both treated groups and week 5 for the 30 ppm and week 6 for the 300 ppm group.

According to the authors, at each interval the increase in fetal deaths was, in part, attributable to a single female that had uterine implants comprised entirely of early fetal deaths. These increases were not considered indicative of a dominant lethal mutagenic response since the second female of the pair mated with the DMF-treated male had high numbers of uterine implants which in most cases were all viable fetal swellings. Histopathology of male reproductive organs revealed no alterations to treatment.
Thus, premating DMF-exposure of the rats for 5 consecutive days did not result in mutagenic effects in the test system.

Applicant's summary and conclusion

Conclusions:

Premating DMF-exposure of the rats for 5 consecutive days did not result in mutagenic effects in the test system.

Executive summary:

Study design

The present study was carried out on the basis of basic scientific principles and was well documented.

In the study male rats were exposed to DMF-vapour (30 und 300 ppm). At least 2 h after the last exposure, two untreated virgin females were placed into each male's cage for 7 days. This mating procedure continued for six consecutive weeks. Females were sacrificed after a gestation period of 11-18 days. At completion of the study the males were sacrificed and necropsy was performed.

Results

All male animals survived until termination of the study. During treatment and during the six week post-treatment mating period all animals were unremarkable. Mean body weights for males exposed to 30 and 300 ppm DMF were slightly lower than the negative control already during pre-treatment. This trend persisted during treatment and post-treatment. Body weight gain during the post-treatment mating period was slightly lower than negative control for the males exposed to 300 ppm DMF. Pregnancy rates and implantation efficiency values of females mated to males exposed to DMF were considered comparable to the negative control throughout the post-treatment period. In contrast, pregnancy rates for the females mated to males of the positive control were lower than the negative control at mating weeks 2, 3 and 4, only at week 4 this difference was statistically significant. Implantation efficiency values were significantly lower at weeks 2-6. Early fetal death data were significantly increased during the entire post-treatment mating period.
Fetal death data for the DMF-treated groups were slightly higher than negative control at week 2 for both treated groups and week 5 for the 30 ppm and week 6 for the 300 ppm group.

According to the authors, at each interval the increase in fetal deaths was, in part, attributable to a single female that had uterine implants comprised entirely of early fetal deaths. These increases were not considered indicative of a dominant lethal mutagenic response since the second female of the pair mated with the DMF-treated male had high numbers of uterine implants which in most cases were all viable fetal swellings. Histopathology of male reproductive organs revealed no alterations to treatment.

Conclusion

Premating DMF-exposure of the rats for 5 consecutive days did not result in mutagenic effects in the test system.