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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
Year of publication: 1991
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991
Reference Type:
other: abstract
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- microencapsulated 2-EH
- Analytical purity: 99%
- Storage condition of test material: mixed feed was stored under refrigerated temperatures in light-protected containers
- 2-EH analysis in feed prior to use: yes; concentrations were found to be 99-108% of the theoretical concentrations

Test animals

Species:
mouse
Strain:
CD-1
Details on test animals and environmental conditions:
- CD-1 Swiss mice
TEST ANIMALS
- Source: Charles River Laboratories Inc., Raleigh, NC, USA
- Weight at study initiation: range 23.52-31.59 g
- Housing: individually in solid-bottom polycarbonate cage swith stainless steel wire lids
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature: 72°F
- Humidity (%): 48
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: microencapsulation
Details on exposure:
DIET PREPARATION
- Rate of preparation of diet (frequency): fed was prepared once. Fresh supplies of dosed feed were obtained from refrigerated stock every 3 days.
- Mixing appropriate amounts with (Type of food): Ground Purina Certified Rodnet Chow
- Storage temperature of food: refrigerated


Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Concentration of 2-EH in the feed was analyzed by gas chromatography (GC) prior to use.
Details on mating procedure:
- Impregnation procedure: purchased timed pregnant
Duration of treatment / exposure:
Gestational days 0 to 17
Frequency of treatment:
7/week
Duration of test:
17 days
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 17, 59, 191 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
28
Control animals:
yes, plain diet
Details on study design:
Microencapsulated 2-EH (0%, 0.009%, 0.03%, or 0.09% in feed) was provided on gestational days (gd) 0 to 17 ad libitum to timed-mated CD-1® mice
(28/group).

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked in table [Appendis I-11] were included.


BODY WEIGHT: Yes
- Time schedule for examinations: gestational day 0, 3, 6. 9. 12, 15, 17


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 17
- Organs examined: liver and uterus


Ovaries and uterine content:
At sacrifice (gd 17), the number of ovarian corpora lutea and uterine implantation sites, including resorptions, and dead or live fetuses, were recorded.
Fetal examinations:
Live and dead fetuses were weighed. Live fetuses were sexed and examined for external, visceral and skeletal malformations and variations.
Statistics:
General Linear Models (GLM) procedures were applied for the analysis of variance (ANOVA) of maternal and fetal parameters. Bartlett's test for homogeneity of variance was performed an all data to be analyzed by ANOVA. When ANOVA revealed a significant (p<0.05) dose effect, Dunnett’s Multiple Comparison Test was used to compare each of the treated groups with the control groups. Other analyses comprised chi square test and Fisher’s exact probability test.
Indices:
none
Historical control data:
not required

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
No dams died, delivered early or were removed from study. Pregnancy rate was high (93-96%) and equivalent across all groups. One litter at 0%
was fully resorbed; all other pregnant animals had live litters at scheduled necropsy. The numbers of live litters evaluated were 27 at 0.009 and
0.03% and 26 at 0 and 0.09% 2-EH.
There was no treatment-related maternal toxicity observed in this study. Maternal body weights, weight gains (absolute or corrected for gravid
uterine weight), gravid uterine weight and liver weight (absolute or relative to body weight) were unaffected. Food consumption (g/kg/day and g/day) was significantly increased for gd 0-3 at 0.09% and unaffected for all other time points evaluated. The calculated consumption of 2-EH, based on gestational food consumption was 0 (0 mmol/kg), 17 (0.13 mmol/kg), 59 (0.46 mmol/kg) and 191 mg/kg/day (1.49 mmol/kg), for the 0, 0.009, 0.03 and 0.090% groups, respectively.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
191 mg/kg bw/day (actual dose received)
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
191 mg/kg bw/day (actual dose received)
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There were no effects of exposure to dietary 2-EH on any gestational parameters. The number of corpora lutea, uterine implantation sites (live, dead, resorbed), pre- and postimplantation loss, sex ratio (%, males) and live fetal body weight per litter (all fetuses or separately by sex) were all equivalent across all groups. There were also no treatment-related changes in the incidence of individual, external, visceral, skeletal or total malformations or variations.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
191 mg/kg bw/day (actual dose received)
Basis for effect level:
other: teratogenicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

No dams died, delivered early or were removed from study. Pregnancy rate was high (93-96%) and equivalent across all groups. One litter at 0% was fully resorbed; all other pregnant animals had live litters at scheduled necropsy. The numbers of live litters evaluated were 27 at 0.009 and 0.03% and 26 at 0 and 0.09% 2-EH. There was no treatment-related maternal toxicity observed in this study. Maternal body weights, weight gains (absolute or corrected for gravid uterine weight), gravid uterine weight and liver weight (absolute or relative to body weight) were unaffected. Food consumption (g/kg/day and g/day) was significantly increased for gestational das 0-3 at 0.09% and unaffected for all other time points evaluated. The calculated consumption of 2-EH, based on gestational food consumption was 0 (0 mmol/kg), 17 (0.13 mmol/kg), 59 (0.46 mmol/kg) and 191 mg/kg/day (1.49 mmol/kg), for the 0, 0.009, 0.03 and 0.090% groups, respectively.

There were no effects of exposure to dietary 2-EH on any gestational parameter. The number of corpora lutea, uterine implantation sites (live, dead, resorbed), pre- and postimplantation loss, sex ratio (%, males) and live fetal body weight per litter (all fetuses or separately by sex) were all equivalent across all groups. There were also no treatment-related changes in the incidence of individual, external, visceral, skeletal or total malformations or variations.

Applicant's summary and conclusion

Conclusions:
No maternal or developmental toxicity was observed in a mouse oral feed study at (equivalent to OECD TG 414, dosing during gestation day 0-17) at any dose up to and including 191 mg/kg bw/day, the highest tested dose.
At equimolar doses, DEHP and and MEHP caused both maternal and developmental toxicity. It was therefore concluded that 2-EH does not play a in DEHP- or MEHP toxicity.
Executive summary:

2-EH was examined in a mouse feed study for its potential for developmental toxicity equivalent to OECD TG 414 and under GLP conditions. Timed pregnant female CD-1 Swiss mice (28 animals/group, body weight range 32.5 to 31.6 g) received 2-EH in the diet at nominal concentrations of 0, 0.009, 0.03, and 0.09% during gestation days 0-17. The animals were housed singly and observations for clinical signs were made daily. Body weights were recorded on gestational day 0, 3, 6, 9, 12, 15, 17. Food consumption and test compound intake were calculated individually. Test substance purity and concentration in thediets wasverified using gas chromatography. Test substance purity was >99%. Concentration in the diets was within 99-108% of the nominal concentration.

 

Maternal effects:

Food intake and hence dose levels were higher than expected. Average intakes were 0, 17, 59, and 191 mg/kg bw/day, respectively. No dams died, delivered early or were removed from study. Pregnancy rates were high (93-96%) and equivalent across all groups. One litter at 0% was fully resorbed; all other pregnant animals had live litters at scheduled necropsy. The numbers of live litters evaluated were 27 at 0.009 and 0.03% and 26 at 0 and 0.09% 2-EH.

There was no treatment-related maternal toxicity observed in this study. Maternal body weights, weight gains (absolute or corrected for gravid uterine weight), gravid uterine weight and liver weight (absolute or relative to body weight) were unaffected. Food consumption (g/kg/day and g/day) was significantly increased for GD 0-3 at 0.09% and unaffected for all other time points evaluated. The calculated consumption of 2-EH, based on gestational food consumption was 0 (0mmol/kg), 17 (0.13mmol/kg), 59 (0.46mmol/kg) and 191 mg/kg/day (1.49mmol/kg), for the 0, 0.009, 0.03 and 0.090% groups, respectively.

 

Fetal effects

There were no effects of exposure to dietary 2-EH on any gestational parameters.The number of corpora lutea, uterine implantation sites (live, dead, resorbed), pre- and postimplantation loss, sex ratio and live fetal body weight per litter (all fetuses or separately by sex) were all equivalent across all groups. There were also no treatment-related changes in the incidence of individual, external, visceral, skeletal or total malformations or variations.

 

In conclusion, there were no maternal or developmental toxic effects of 2-EH dietary exposure throughout gestation at any concentration tested, in contrast to the qualitatively similar maternal and developmental toxicity previously reported for DEHP (Tyl et al., 1988) and MEHP (NTP, 1990) at approximately equimolar doses administered under comparable experimental conditions. The present study therefore indicates that 2-EH plays essentially no role in the expression of DEHP-induced maternal and developmental toxicity. The NOAEL for maternal toxicity and for developmental toxicity and teratogenicity was therefore 191 mg/kg bw/day, the highest dose level tested.

 

This study was conducted equivalent to OECD TG 414 and under GLP conditions, and it is considered to be valid without restriction (Tyl et al., 1991).