2-dimethylaminoethanol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not reported, published in 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: no data on GLP or OECD compliance. Acceptable, well documented publication which meets basic scientific principles.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

not reported, published 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: no data on GLP or OECD compliance. Acceptable, well ducumented publication which meets basic scientific principles.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague-Dawley, Inc., Indianapolis, IN.
- Age at study initiation: 67-79 days old on arrival
- Weight at study initiation: not reported
- Fasting period before study: no
- Housing: in stainless-steel wire-meshcages
- Diet (e.g. ad libitum): ad libitum except during exposure
- Water (e.g. ad libitum): ad libitum except during exposure
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): not reported
- Humidity (%): not reported
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light):12/12

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Liquid DMEA was metered from a piston pump into a heated glass maintained at the lowest temperature to vaporize the liquid. The resultant vapor was carried into the exposure chamber by a countercurrent flow of conditioned air through the evaporator. Exposure was conducted in 4320-litre stainless-steel and glass chambers at an airflow of 1000 L/min.

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: no data
- Proof of pregnancy: [vaginal plug ] referred to as [day 0] of pregnancy
- After successful mating each pregnant female was caged (how): singly

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber atmosphere was analyzed for DMEA concentrations once every 32 min during each 6-h exposure, using a Perkin-Elmer 3920B gas chromatograph equipped with a flame ionization detector. Nominal concentrations weere calculated daily based on the amount of DMAE used and the chamber tube air flow during the exposure period.

Duration of treatment / exposure:

6 hours

Frequency of treatment:

on gestational days 6-15

Dose / conc.:

0 ppm (nominal)

Dose / conc.:

10 ppm (nominal)

Dose / conc.:

30 ppm (nominal)

Dose / conc.:

100 ppm (nominal)

No. of animals per sex per dose:

In a range-finding study, eight plug-positive females each were assigned to four DMEA-exposed groups (target DMEA concentrations 8, 25, 75 and 100 ppm) and an air-exposed control group.
In the definitive study, 25 plug-positive females each were assigned to three DMEA-exposed groups (10, 30 and 100 ppm) and a control group.

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Based on the results of the range-finding study.
The highest exposure concentration in the range-finding study, 100 ppm, was retained in the definitive study since it produced maternal toxicity (reduced body weights and weight gain, and clinical signs) and possible embryotoxicity (increased preimplantation loss) but no apparent fetotoxicity. The middle exposure concentration of 30 ppm chosen for the definitive study was slightly above the 25 ppm in the range-finding study which produced maternal toxicity (transient weight gain depression and clinical signs limited to the eyes) and possible embryotoxicity (reduced implantations, increased preimplantation loss and reduced number of viable fetuses per litter). The lowest exposure concentration, 10 ppm, was chosen as essentially the same as the 8 ppm in the range-finding study which produced no effects on maternal weights and only transient ocular changes and no evidence of embryofetal toxicity.
- Rationale for animal assignment (if not random): randomized

Positive control:

no

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: Maternal body weights were measured on gd 0, 6, 12, 15, 18 and 21.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: The gravid uterus, ovaries (including corpora lutea), cervix, vagina and peritoneal and thoracic cavities were examined grossly. Ovarian corpora lutea of pregnancy were counted. Maternal liver and uterine weights were measured.

Oestrous cyclicity (parental animals):

no

Sperm parameters (parental animals):

no

Litter observations:

STANDARDISATION OF LITTERS
- Performed ongestation day 21
- If yes, maximum of [..all ] pups/litter

PARAMETERS EXAMINED
The following parameters were examined in [F1 ] offspring: [number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities, other:]

GROSS EXAMINATION OF DEAD PUPS:
[no / yes, for external and internal abnormalities; possible cause of death was/was not determined for pups born or found dead.]

Postmortem examinations (parental animals):

SACRIFICE
- Maternal animals: All surviving animals [on gd 21]

GROSS NECROPSY
- Gross necropsy consisted of [external and internal examinations including the cervical, thoracic, and abdominal viscera.]

HISTOPATHOLOGY /
The tissues indicated in Table [#] were prepared for microscopic examination and weighed, respectively.

OTHER:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Uteri were examined externally for signs of hemorrhage. All live and dead fetuses were recorded

Postmortem examinations (offspring):

- External examinations: Yes: [all per litter] including cleft palate
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [half per litter]
- Head examinations: Yes: [half per litter]

Statistics:

The unit of comparison was the pregnant female or the litter. Continuous quantitative data were compared between the DMEA-exposed groups and air-exposed control group by the use of Levene's test for equal variances analysis of variance (ANOVA) and t-tests with Bonferroni probabilities. The t-tests were used when the F value from the ANOVA was significant. When Levene's test indicated homogeneous variances, and the ANOVA was significant, the pooled t-test was used. When Levene's test indicated heterogeneous variances, all groups were compared by an ANOVA for unequal variances," followed by the separate variance t-test when necessary. Non-parametric data obtained following laparohysterectomy were statistically treated using the Kruskal- Wallis test followed by the Mann-Whitney U test when appropriate. Incidence data were compared using Fisher's exact test. For all statistical tests, the fiducial limit of 0.05 (two-tailed) was used as the criterion for significance.

Reproductive indices:

listed in the tables 1 and 3 in "Remarks on results"

Offspring viability indices:

listed in the table 3 in "Remarks on results"

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

not examined

Other effects:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, treatment-related

Table 1 (in "Remarks on results") shows the pregnancy and litter data of all plug-positive females on study. There were no maternal deaths or abortions. Pregnancy rate ranged from 88 to 96% and all pregnant females had one or more live fetuses at scheduled sacrifice, except one dam at 100 ppm, which had a totally resorbed litter. Reduced body weight and reduced body weight gain were observed at 100 ppm (Table 2). Body weight reduced on gd 12 and 15 (during the exposure period) and on gd 15 and 21 (postexposure period). Body weight gain was reduced for all intervals except gd 6- 9 (pre-exposure) and gd 15-21 (post-exposure). There were no effects on body weight or body weight gain for the 10 or 30 ppm groups. Clinical examination showed that dams at 100 ppm only exhibited perinasal fur discoloration, presumably from chromodacryorrhea. At 30 and 100 ppm there were darkened (maroon), cloudy and hazy eyes, slight corneal vascularization and pupils dilated and fixed. Cloudy and hazy eyes were observed only during the exposure period. Darkened eyes were also observed at 10 ppm during the exposure period. There were no statistically significant differences in gravid uterine weight and absolute or relative liver weights between the DMEA-exposed groups and the controls.

Dose descriptor:

NOAEC

Effect level:

10 ppm (nominal)

Sex:

female

Basis for effect level:

other: ocular effects, reduced body weight. In dams, no effects related to treatment.

Clinical signs:

effects observed, treatment-related

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, treatment-related

Histopathological findings:

no effects observed

The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed. Fetal body weights were elevated at 100 ppm relative to those in controls (Table 3), and only one skeletal district, the cervical centra, exhibited evidence of reduced ossification at 100 ppm (Table 4), an exposure concentration which also produced maternal toxicity. This finding is the only one which could be consistent with indicating possible minimal fetotoxicity; however, there were no other indications of fetotoxicity, such as reduced fetal body weight. No other skeletal districts, of the number identified as sensitive indicators of delayed development in rat fetuses,” exhibited a delay in ossification. No increases in malformations were observed at any concentration of DMEA employed, including those which produced maternal toxicity.

Reproductive effects observed:

not specified

Table 1. Pregnancy and litter data for Fischer 344 rats exposed whole body to N,N-dimethylethanolamine vapor
Exposure concentration (ppm)	0	10	30	100
Number in study	25	25	25	25
Number of early delivery	1	0	0	0
Number aborted	0	0	0	0
Number (%) pregnant at scheduled	22	23	22	24
sacrifice	(91.7)	(92.0)	(88.0)	(96.0)
Number of litters examined	22	23	22	23^a
^aOne dam carried a totally resorbed litter.

Table 2. Maternal body weights and weight gains in Fischer 344 rats exposed whole body to N,N-dimethyIethanoIamine vapor
Exposure conc. (ppm)	0	10	30	100
Number of dams	22	23	22	24
Maternal body weight^3
gd 0	166.0 ± 8.1	165.0 ± 6.3	166.3 ± 7.6	166.6 ± 6.7
gd 6	178.1 ± 9.0	177.5 ± 5.9	178.8 ± 6.9	179.0 ± 7.4
gd 9	183.3 ± 9.9	181.8 ± 5.8	184.0 ± 6.7	179.8 ± 7.7
gd 12	193.1 ± 10.2	191.2 ± 6.0	193.4 ± 7.8	183.0 ± 8.2**
gd 15	203.3 ± 10.8	200.0 ± 7.2	203.6 ± 8.9	187.4 ± 8.7***
gd 18	223.7 ± 12.5	218.1 ± 9.2	221.9 ± 11.4	207.9 ± 12.5***
gd 21	246.6 ± 15.6	238.2 ± 15.2	243.5 ± 17.6	233.1 ± 18.1*
Body weight change^3
gd 0-6 (pre-exposure)	12.1 ± 4.6	12.5 ± 3.2	12.5 ± 3.5	12.4 ± 3.1
gd 6-9	5.2 ± 3.3	4.3 ± 1.9	5.2 ± 2.8	0.7 ± 2.5***
gd 6-12	15.0 ± 3.4	13.8 ± 2.4	14.6 ± 3.4	4.0 ± 5.1***
gd 6-15 (exposure)	25.2 ± 5.1	22.6 ± 3.2	24.8 ± 5.3	8.4 ± 5.7***
gd 6-18	45.6 ± 7.4	40.6 ± 5.7	43.1 ± 9.3	28.9 ± 10.3***
gd 6-21	68.5 ± 9.9	60.7 ± 12.2	64.7 ± 16.2	54.1 ± 16.6**
gd 15-21 (postexposure)	43.3 ± 6.7	38.2 ± 9.9	39.9 ±11.9	45.7 ± 13.0
^aln grams, mean ± SD. *p < 0.05; **p < 0.01 and ***p < 0.001 versus control.

Table 3. Gestational parameters and fetal body weights in Fischer 344 rats exposed whole body toN,N-dimethylethanolamine vapor*
Exposure conc. (ppm)	0	10	30	100
Number of dams	22	23	22	24
Corpora lutea/dam	11.4 ± 1.2	11.1 ± 1.2^b	11.3 ± 1.1	11.8 ± 1.2
Total implants/litter	9.6 ± 1.7	7.9 ± 3.0	8.6 ± 3.3	8.5 ± 3.0
Preimplantation loss (%)	15.5 ± 14.6	26.9 ± 25.4^b	25.9 ± 26.8	28.1 ± 24.3
Viable implants/litter	9.5 ± 1.7	7.6 ± 3.1*	8.5 ± 3.4	8.0 ± 3.3
Non-viable implants/litter	0.0 ± 0.2	0.3 ± 0.6	0.1 ± 0.4	0.5 ± 1.5
Early resorptions	0.0 ± 0.0	0.2 ± 0.5	0.0 ± 0.2	0.4 ± 1.4
Late resorptions	0.0 ± 0.2	0.1 ± 0.3	0.1 ± 0.3	0.0 ± 0.0
Dead fetuses	0.0 ± 0.0	0.0 ± 0.2	0.0 ± 0.0	0.0 ± 0.2
Live fetuses/litter (%/litter)	99.5 ± 2.4	95.6 ± 9.0*	97.9 ± 6.1	94.4 ± 20.6
Sex ratio (% males)	56.0 ± 16.0	60.0 ± 21.0	41.6 ± 18.4*	49.0 ± 16.9^c
Live litter size	9.5 ± 1.7	7.6 ± 3.1*	8.5 ± 3.4	8.4 ± 2.9^c
Fetal body weight/litter (g)
All fetuses	4.47 ± 0.15	4.56 ± 0.26	4.53 ± 0.24	4.66 ± 0.27^c
Male fetuses	4.63 ± 0.16	4.67 ± 0.24	4.61 ± 0.26^d	4.82 ± 0.26*^c
Female fetuses	4.28 ± 0.13	4.38 ± 0.26^e	4.43 ± 0.26	4.52 ± 0.30**^c
^aValues presented as mean ± standard deviations; *p < 0.05 and **p < 0.01 versus control. ^bn = 22 because the corpora lutea count from one dam was inadvertently not recorded. ^cn = 23 because one dam carried a totally resorbed litter. ^dn = 20 because two litters consisted of only female fetuses. ^en = 22 because one litter consisted of only male fetuses.

Table 4. Skeletal variations in the fetuses of Fischer 344 rats exposed whole body toN,N-dimethylethanolamine vapor
	Fetuses				Litters
Exposure concentration (ppm)	0	10	30	100	0	10	30	100
Number examined skeletally	102	82	89	91	22	23	20	23
Cervical centrum 6 poorly ossified	43	46	48	33	22	21	18	15**
Cervical centra 1, 2, 3 and/or 4 split	3	2	6	13	3	2	5	12*
Thoracic centrum 1 bilobed	8	14	15	11	6	14*	12	10
Thoracic centrum 9 bilobed	14	5	6	6	12	5*	6	6
Some proximal phalanges (forelimb) unossified	7	0	5	5	6	0*	5	5
Sternebra 5 bilobed	16	10	6	14	12	5*	5	11
*p < 0.05 and **p < 0.01 versus control.

Conclusions:

In summary, whole-body exposure to DMEA vapor of timed-pregnant Fischer 344 rats during organogenesis at 0, 10, 30 or 100 ppm resulted in maternal toxicity at 30 and 100 ppm (with transient minor ocular changes at 10 ppm). There was no evidence of embryonic or fetal toxicity, including teratogenicity, at any exposure concentration employed. Therefore, the no-observed-adverse-effect level is around 10 ppm for maternal toxicity and ≥ 100 ppm for embryofetal toxicity and teratogenicity in this study.

Executive summary:

Timed-pregnant Fischer 344 rats were exposed whole body to N,N-dimethylethanolamine vapor for 6 h per day on gestational days 6-15 at mean (±SD) analytically measured concentrations of 10.4 ± 0.86, 29.8 ± 2.14 and 100 ± 4.9 ppm. Dams were sacrificed on gestational day 21. There was no maternal mortality in any exposed groups. Maternal toxicity observed in the 100 ppm group included reduced body weight during and after exposures, reduced weight gain during exposure and ocular changes (darkened, cloudy and hazy eyes, slight corneal vascularization and fixed, dilated pupils). Ocular effects were also noted in the other two exposure groups; the effects were quite marked at 30ppm but only minimal and transient at 10 ppm. There were no effects of treatment on any gestational parameters, including pre- and postimplantation loss or sex ratio. Fetal body weights per litter were statistically significantly increased at 100 ppm relative to controls. There were no increases in the incidences of total malformations by category (external, visceral or skeletal) or individually. The incidence of six skeletal variations out of 120 noted differed in exposed groups relative to that of control. Four of these variations were decreases in incidence; only one fetal variation, the split (bipartite) cervical centrum, was elevated at 100 ppm relative to controls. In the absence of any other indications of delayed ossification or fetal body weights, the observed fetal variation does not suggest a consistent pattern of fetal toxicity. Hence, the no-observed-adverse-effect level is around 10 ppm for maternal toxicity and at or above 100 ppm for embryofetal toxicity and teratogenicity.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1996

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-dimethylaminoethanol

EC Number:

203-542-8

EC Name:

2-dimethylaminoethanol

Cas Number:

108-01-0

Molecular formula:

C4H11NO

IUPAC Name:

2-(dimethylamino)ethanol

Details on test material:

- Name of test material (as cited in study report): N,N-Dimethylethanolamine (DMEA) supplied by Union Carbide Corporation, South Charleston, WV.
- Substance type: organic
- Physical state: liquid
- Analytical purity: the test material remained at least 99.7% pure throughout the study
- Impurities (identity and concentrations): no
- Composition of test material, percentage of components: No significant compositional changes occurred
The purity and stability were verified before onset of exposures and after the exposures were completed.

Test animals

Species:

rat

Strain:

Fischer 344

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague-Dawley, Inc., Indianapolis, IN.
- Age at study initiation: 67-79 days old on arrival
- Weight at study initiation: not reported
- Fasting period before study: no
- Housing: in stainless-steel wire-meshcages
- Diet (e.g. ad libitum): ad libitum except during exposure
- Water (e.g. ad libitum): ad libitum except during exposure
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): not reported
- Humidity (%): not reported
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light):12/12

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

unchanged (no vehicle)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Liquid DMEA was metered from a piston pump into a heated glass maintained at the lowest temperature to vaporize the liquid. The resultant vapor was carried into the exposure chamber by a countercurrent flow of conditioned air through the evaporator. Exposure was conducted in 4320-litre stainless-steel and glass chambers at an airflow of 1000 L/min.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chamber atmosphere was analyzed for DMEA concentrations once every 32 min during each 6-h exposure, using a Perkin-Elmer 3920B gas chromatograph equipped with a flame ionization detector. Nominal concentrations were calculated daily based on the amount of DMEA used and the chamber tube air flow during the exposure period.

Details on mating procedure:

- Impregnation procedure:[cohoused]
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: not reported

- Further matings after two unsuccessful attempts: [no]
- Verification of same strain and source of both sexes: [yes / no (explain)]
- Proof of pregnancy: [vaginal plug] referred to as [day 0] of pregnancy
- Any other deviations from standard protocol:

Duration of treatment / exposure:

6 h per day

Frequency of treatment:

each day

Duration of test:

on gestational days 6-15

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 ppm (nominal)

Doses / concentrations 2

Dose / conc.:

10 ppm (nominal)

Doses / concentrations 3

Dose / conc.:

30 ppm (nominal)

Doses / concentrations 4

Dose / conc.:

100 ppm (nominal)

No. of animals per sex per dose:

In a range-finding study, eight plug-positive females each were assigned to four DMEA-exposed groups (target DMEA concentrations 8, 25, 75 and 100 ppm) and an air-exposed control group.
In the definitive study, 25 plug-positive females each were assigned to three DMEA-exposed groups (10, 30 and 100 ppm) and a control group.

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Based on the results of the range-finding study.
The highest exposure concentration in the range-finding study, 100 ppm, was retained in the definitive study since it produced maternal toxicity (reduced body weights and weight gain, and clinical signs) and possible embryotoxicity (increased preimplantation loss) but no apparent fetotoxicity. The middle exposure concentration of 30 ppm chosen for the definitive study was slightly above the 25 ppm in the range-finding study which produced maternal toxicity (transient weight gain depression and clinical signs limited to the eyes) and possible embryotoxicity (reduced implantations, increased preimplantation loss and reduced number of viable fetuses per litter). The lowest exposure concentration, 10 ppm, was chosen as essentially the same as the 8 ppm in the range-finding study which produced no effects on maternal weights and only transient ocular changes and no evidence of embryofetal toxicity.
- Rationale for animal assignment (if not random): randomized

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes - Time schedule: daily
DETAILED CLINICAL OBSERVATIONS: Yes - Time schedule: daily
BODY WEIGHT: Yes - Time schedule for examinations:Maternal body weights were measured on gd 0, 6, 12, 15, 18 and 21.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: The gravid uterus, ovaries (including corpora lutea), cervix, vagina and peritoneal and thoracic cavities were examined grossly. Ovarian corpora lutea of pregnancy were counted. Maternal liver and uterine weights were measured.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: Uteri were examined externally for signs of hemorrhage. All live and dead fetuses were recorded-

Fetal examinations:

- External examinations: Yes: [all per litter] including cleft palate
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [half per litter]
- Head examinations: Yes: [half per litter]

Statistics:

The unit of comparison was the pregnant female or the litter. Continuous quantitative data were compared between the DMEA-exposed groups and air-exposed control group by the use of Levene's test for equal variances analysis of variance (ANOVA) and t-tests with Bonferroni probabilities. The t-tests were used when the F value from the ANOVA was significant. When Levene's test indicated homogeneous variances, and the ANOVA was significant, the pooled t-test was used. When Levene's test indicated heterogeneous variances, all groups were compared by an ANOVA for unequal variances," followed by the separate variance t-test when necessary. Non-parametric data obtained following laparohysterectomy were statistically treated using the Kruskal- Wallis test followed by the Mann-Whitney U test when appropriate. Incidence data were compared using Fisher's exact test. For all statistical tests, the fiducial limit of 0.05 (two-tailed) was used as the criterion for significance.

Indices:

listed in the table 4 in "Remarks on results"

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical examination showed that dams at 100 ppm only exhibited perinasal fur discoloration, presumably from chromodacryorrhea. At 30 and 100 ppm there were darkened (maroon), cloudy and hazy eyes, slight corneal vascularization and pupils dilated and fixed. Cloudy and hazy eyes were observed only during the exposure period. Darkened eyes were also observed at 10 ppm during the exposure period.

Mortality:

no mortality observed

Description (incidence):

There were no maternal deaths or abortions.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Reduced body weight and reduced body weight gain were observed at 100 ppm. Body weight reduced on gd 12 and 15 (during the exposure period) and on gd 15 and 21 (postexposure period). Body weight gain was reduced for all intervals except gd 6- 9 (pre-exposure) and gd 15-21 (post-exposure). There were no effects on body weight or body weight gain for the 10 or 30 ppm groups.

Ophthalmological findings:

effects observed, treatment-related

Description (incidence and severity):

At 30 and 100 ppm there were darkened (maroon), cloudy and hazy eyes, slight corneal vascularization and pupils dilated and fixed. Cloudy and hazy eyes were observed only during the exposure period. Darkened eyes were also observed at 10 ppm during the exposure period.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no statistically significant differences in gravid uterine weight and absolute or relative liver weights between the DMEA-exposed groups and the controls.

Description (incidence and severity):

There were no effects of treatment on gonads.

Maternal developmental toxicity

Number of abortions:

no effects observed

Description (incidence and severity):

There were no maternal deaths or abortions.

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

There were no effects of treatment on pre- and post implantation loss.

Description (incidence and severity):

Pregnancy rate ranged from 88 to 96% and all pregnant females had one or more live fetuses at scheduled sacrifice, except one dam at 100 ppm, which had a totally resorbed litter.

Description (incidence and severity):

Pregnancy rate ranged from 88 to 96% and all pregnant females had one or more live fetuses at scheduled sacrifice, except one dam at 100 ppm, which had a totally resorbed litter.

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

There were no effects of treatment on any gestational parameters.

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

Pregnancy rate ranged from 88 to 96% and all pregnant females had one or more live fetuses at scheduled sacrifice, except one dam at 100 ppm, which had a totally resorbed litter.

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Table 2 (in "Remarks on results") shows the pregnancy and litter data of all plug-positive females on study. There were no maternal deaths or abortions. Pregnancy rate ranged from 88 to 96% and all pregnant females had one or more live fetuses at scheduled sacrifice, except one dam at 100 ppm, which had a totally resorbed litter. Reduced body weight and reduced body weight gain were observed at 100 ppm. Body weight reduced on gd 12 and 15 (during the exposure period) and on gd 15 and 21 (postexposure period). Body weight gain was reduced for all intervals except gd 6- 9 (pre-exposure) and gd 15-2 1 (post-exposure). There were no effects on body weight or body weight gain for the 10 or 30 ppm groups. Clinical examination showed that dams at 100 ppm only exhibited perinasal fur discoloration, presumably from chromodacryorrhea. At 30 and 100 ppm there were darkened (maroon), cloudy and hazy eyes, slight corneal vascularization and pupils dilated and fixed. Cloudy and hazy eyes were observed only during the exposure period. Darkened eyes were also observed at 10ppm during the exposure period. There were no statistically significant differences in gravid uterine weight and absolute or relative liver weights between the DMEA-exposed groups and the controls.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

10 ppm (nominal)

Basis for effect level:

body weight and weight gain

clinical signs

ophthalmological examination

other: maternal toxicity

Results (fetuses)

Fetal body weight changes:

no effects observed

Description (incidence and severity):

Fetal body weights were elevated at 100 ppm relative to those in controls.

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed.

Changes in sex ratio:

no effects observed

Description (incidence and severity):

The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed. There were no effects of treatment on sex ratio.

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed.

Changes in postnatal survival:

no effects observed

Description (incidence and severity):

The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed.

External malformations:

no effects observed

Description (incidence and severity):

No increases in malformations were observed at any concentration of DMEA employed, including those which produced maternal toxicity.

Skeletal malformations:

no effects observed

Description (incidence and severity):

One skeletal district, the cervical centra, exhibited evidence of reduced ossification at 100 ppm, an exposure concentration which also produced maternal toxicity. This finding is the only one which could be consistent with indicating possible minimal fetotoxicity; however, there were no other indications of fetotoxicity, such as reduced fetal body weight. No other skeletal districts, of the number identified as sensitive indicators of delayed development in rat fetuses,” exhibited a delay in ossification. No increases in malformations were observed at any concentration of DMEA employed, including those which produced maternal toxicity.

Visceral malformations:

no effects observed

Description (incidence and severity):

No increases in malformations were observed at any concentration of DMEA employed, including those which produced maternal toxicity.

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The present developmental toxicity evaluation revealed no treatment-related embryotoxicity at any exposure concentration employed. No consistent pattern of fetotoxicity was observed. Fetal body weights were elevated at 100 ppm relative to those in controls (Table 3), and only one skeletal district, the cervical centra, exhibited evidence of reduced ossification at 100 ppm (Table 4), an exposure concentration which also produced maternal toxicity. This finding is the only one which could be consistent with indicating possible minimal fetotoxicity; however, there were no other indications of fetotoxicity, such as reduced fetal body weight. No other skeletal districts, of the number identified as sensitive indicators of delayed development in rat fetuses,” exhibited a delay in ossification. No increases in malformations were observed at any concentration of DMEA employed, including those which produced maternal toxicity.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

>= 100 ppm (nominal)

Basis for effect level:

other: see "Remarks"

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Table 2. Pregnancy and litter data for Fischer 344 rats exposed whole body to N,N-dimethylethanolamine vapor
Exposure concentration (ppm)	0	10	30	100
Number in study	25	25	25	25
Number of early delivery	1	0	0	0
Number aborted	0	0	0	0
Number (%) pregnant at scheduled	22	23	22	24
sacrifice	(91.7)	(92.0)	(88.0)	(96.0)
Number of litters examined	22	23	22	23^a
^aOne dam carried a totally resorbed litter.

Table 3. Gestational parameters and fetal body weights in Fischer 344 rats exposed whole body to N,N-dimethylethanolamine vapor*
Exposure conc. (ppm)	0	10	30	100
Number of dams	22	23	22	24
Corpora lutea/dam	11.4 ± 1.2	11.1 ± 1.2^b	11.3 ± 1.1	11.8 ± 1.2
Total implants/litter	9.6 ± 1.7	7.9 ± 3.0	8.6 ± 3.3	8.5 ± 3.0
Preimplantation loss (%)	15.5 ± 14.6	26.9 ± 25.4^b	25.9 ± 26.8	28.1 ± 24.3
Viable implants/litter	9.5 ± 1.7	7.6 ± 3.1*	8.5 ± 3.4	8.0 ± 3.3
Non-viable implants/litter	0.0 ± 0.2	0.3 ± 0.6	0.1 ± 0.4	0.5 ± 1.5
Early resorptions	0.0 ± 0.0	0.2 ± 0.5	0.0 ± 0.2	0.4 ± 1.4
Late resorptions	0.0 ± 0.2	0.1 ± 0.3	0.1 ± 0.3	0.0 ± 0.0
Dead fetuses	0.0 ± 0.0	0.0 ± 0.2	0.0 ± 0.0	0.0 ± 0.2
Live fetuses/litter (%/litter)	99.5 ± 2.4	95.6 ± 9.0*	97.9 ± 6.1	94.4 ± 20.6
Sex ratio (% males)	56.0 ± 16.0	60.0 ± 21.0	41.6 ± 18.4*	49.0 ± 16.9^c
Live litter size	9.5 ± 1.7	7.6 ± 3.1*	8.5 ± 3.4	8.4 ± 2.9^c
Fetal body weight/litter (g)
All fetuses	4.47 ± 0.15	4.56 ± 0.26	4.53 ± 0.24	4.66 ± 0.27^c
Male fetuses	4.63 ± 0.16	4.67 ± 0.24	4.61 ± 0.26^d	4.82 ± 0.26*^c
Female fetuses	4.28 ± 0.13	4.38 ± 0.26^e	4.43 ± 0.26	4.52 ± 0.30**^c
^aValues presented as mean ± standard deviations; *p < 0.05 and **p < 0.01 versus control. ^bn = 22 because the corpora lutea count from one dam was inadvertently not recorded. ^cn = 23 because one dam carried a totally resorbed litter. ^dn = 20 because two litters consisted of only female fetuses. ^en = 22 because one litter consisted of only male fetuses.

Table 4. Skeletal variations in the fetuses of Fischer 344 rats exposed whole body to N,N-dimethylethanolamine vapor
	Fetuses				Litters
Exposure concentration (ppm)	0	10	30	100	0	10	30	100
Number examined skeletally	102	82	89	91	22	23	20	23
Cervical centrum 6 poorly ossified	43	46	48	33	22	21	18	15**
Cervical centra 1, 2, 3 and/or 4 split	3	2	6	13	3	2	5	12*
Thoracic centrum 1 bilobed	8	14	15	11	6	14*	12	10
Thoracic centrum 9 bilobed	14	5	6	6	12	5*	6	6
Some proximal phalanges (forelimb) unossified	7	0	5	5	6	0*	5	5
Sternebra 5 bilobed	16	10	6	14	12	5*	5	11
*p < 0.05 and **p < 0.01 versus control.

Applicant's summary and conclusion

Conclusions:

In summary, whole-body exposure to DMEA vapor of timed-pregnant Fischer 344 rats during organogenesis at 0, 10, 30 or 100 ppm resulted in maternal toxicity at 30 and 100 ppm (with transient minor ocular changes at 10 ppm). There was no evidence of embryonic or fetal toxicity, including teratogenicity, at any exposure concentration employed. Therefore, the no-observed-adverse-effect level (NOAEL) is around 10 ppm for maternal toxicity and ≥ 100 ppm for embryofetal toxicity and teratogenicity in this study.

Executive summary:

Timed-pregnant Fischer 344 rats were exposed whole body to N,N-dimethylethanolamine vapor for 6 h per day on gestational days 6-15 at mean (± SD) analytically measured concentrations of 10.4 ± 0.86, 29.8 ± 2.14 and 100 ± 4.9 ppm. Dams were sacrificed on gestational day 21. There was no maternal mortality in any exposed groups. Maternal toxicity observed in the 100 ppm group included reduced body weight during and after exposures, reduced weight gain during exposure and ocular changes (darkened, cloudy and hazy eyes, slight corneal vascularization and fixed, dilated pupils). Ocular effects were also noted in the other two exposure groups; the effects were quite marked at 30 ppm but only minimal and transient at 10 ppm. There were no effects of treatment on any gestational parameters, including pre- and postimplantation loss or sex ratio. Fetal body weights per litter were statistically significantly increased at 100 ppm relative to controls. There were no increases in the incidences of total malformations by category (external, visceral or skeletal) or individually. The incidence of six skeletal variations out of 120 noted differed in exposed groups relative to that of control. Four of these variations were decreases in incidence; only one fetal variation, the split (bipartite) cervical centrum, was elevated at 100 ppm relative to controls. In the absence of any other indications of delayed ossification or fetal body weights, the observed fetal variation does not suggest a consistent pattern of fetal toxicity. Hence, the no-observed-adverse-effect level (NOAEL) is around 10 ppm for maternal toxicity and at or above 100 ppm for embryofetal toxicity and teratogenicity.