2-ethylhexane-1,3-diol

Toxicity to reproduction

Administrative data

Endpoint:

toxicity to reproduction

Remarks:

other: Teratology study with information on fertility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Published in a peer-reviewed journal

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1994

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 414

Principles of method if other than guideline:

GLP teratology study with information on fertility

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexane-1,3-diol

EC Number:

202-377-9

EC Name:

2-ethylhexane-1,3-diol

Cas Number:

94-96-2

Molecular formula:

C8H18O2

IUPAC Name:

2-ethylhexane-1,3-diol

Test material form:

liquid: viscous

Details on test material:

Purity 99%.
Analysis by NMR and GC/MS

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc. Portage, MI, USA
- Age at study initiation:
- Weight at study initiation: 250-300 g (males) and 175-200 g (females)
- Housing: two per cage, in stainless steel wire mesh cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad liitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68-75 F.
- Humidity (%): 42-65
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

dermal

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: 1.5 x 1.5 inches
- % coverage:
- Type of wrap if used: occlusive, polyvinyl film over sterilized gauze square. A Lycra-Spandex jacket with Velcro closure covered the dosing site.
- Time intervals for shavings or clipplings: no data, but skin was clipped

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes, warm water-dampened gauze
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):1.0-4.0 ml/day
- Concentration (if solution): 100%
- Constant volume or concentration used: no

USE OF RESTRAINERS FOR PREVENTING INGESTION: no; applied to dorsal trunk not accessible to mouth

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Proof of mating: The presence of a dropped copulation plug was considered evidence of successful mating, and designated as gestation day (gd) 0

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

not required for undiluted material

Duration of treatment / exposure:

10 days during gestation

Frequency of treatment:

once daily

Details on study schedule:

Days 6-15 (inclusive) during gestation

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
4.0 ml/kg bw/d
Basis:
other: undiluted test article based on maternal body weight on GD 6. Equivalent to 3768 mg/kg bw/d.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
2.0 ml/kg bw/d
Basis:
other: undiluted test article based on maternal body weight on GD 6. Equivalent to 1884 mg/kg bw/d.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
1.0 ml/kg bw/d
Basis:
other: undiluted test article based on maternal body weight on GD 6. Equivalent to 942 mg/kg bw/d.

No. of animals per sex per dose:

25 successfully-mated females per dose group

Control animals:

yes

Details on study design:

Controls were animals where 4.0 ml of water was applied under identical occlusive patches
- Dose selection rationale: Doses were those found to include the NOAEL for repeated dose exposure (see Section 7.5.2, Van Miller, 1994)
- Rationale for animal assignment (if not random): randomly assigned by computer-generated procedure.

Positive control:

none

Examinations

Parental animals: Observations and examinations:

Assessments made on females only.
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily, twice daily during the treatment period

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily, twice daily during the treatment period for clinical signs of toxicity or pharmacologic effects and local skin irritation

BODY WEIGHT: Yes
- Time schedule for examinations: on days 0, 6, 9, 12, 15, 18 and 21

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, over 3-day intervals from GD 0 to 21.
- Compound intake was calculated as time-weighted averages from the consumption and body weight gain data: No data

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #21 by CO2 asphyxiation
- Organs examined: gravid uterus, ovaries and other pelvic and abdominal visceral were inspected for signs of gross pathology

Oestrous cyclicity (parental animals):

not examined

Sperm parameters (parental animals):

not examined

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: no, on GD 21.

PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 / F3] offspring:
[number of corpora lutea, total implants per litter, % preimplantation loss, early and late resorptions, number and sex of pups, sex ratios, stillbirths and dead fetuses, live births, postnatal mortality at GD 21, presence of gross anomalies]

GROSS EXAMINATION OF DEAD PUPS:
[yes, for external and internal abnormalities]

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: no
- Maternal animals: All survival animals [sacrificed on GD21]

GROSS NECROPSY
- Gross necropsy consisted of [the gravid uterus, ovaries, and other pelvic and abdominal viscera. Ovarian corpora lutea were counted. Maternal and gravid uterine weights were measured. Uteri were dissected longitudinally, and live and dead fetuses and resorption sites counted.

HISTOPATHOLOGY / ORGAN WEIGHTS: yes

Postmortem examinations (offspring):

GROSS NECROPSY
- Gross necropsy consisted of [external and internal examinations including the cervical and abdominal viscera. One-half of each litter was examined for thoracoabdominal visceral abnormalities. These fetuses were decapitated and the heads fixed in Bouin's fluid for subsequent examination of craniofacial abnormalities using sectioning methods. The remaining fetuses in each litter were eviscerated, fixed in ethanol, processed for staining with alizarin red S, and examined for skeletal malformations and variations.]

Statistics:

The unit of comparison was the pregnant female or the litter. Quantitative continuous variables were intercompared using Levene's test for equal variances, ANOVA and t-tests with Bonferroni probablilities for pairwise comparisons. When Levene's test indicated heterogeneous variances, all groups were compared by an analysis of variance for unequal variances followed, if necessary, by the separate variance t-test.
Nonparametric data were analyzed statistically by the Kruskal-Wallis test followed by a Mann-Whitney U-test, if appropriate. Incidence data were compared using Fisher's exact test. For all statistical tests, a probability value of p < 0.05 (two-tailed) was used as the criterion for significance.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Decreased body weight gain, mild skin irritation and increased liver weights

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weights were decreased at the high dose

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Body weights were decreased at the high dose

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not examined

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

not examined

Details on results (P0)

No erythema or edema was seen at the dosing site. Exfoliation and crusting, possibly related to drying, were seen in a few animals of the mid and high dose groups.

One moribund female of the high dose group was sacrificed on GD11. Necropsy showed hydronephrosis and urinary bladder calculi and therefore death was considered not to be related to treatment. Corrected body weight change was slightly but not statistically significantly reduced at the high dose. Although not significant, maternal body weight gains were lower than for controls for the high dose group over the whole treatment period, particularly during the first 3 days of treatment. There were no significant or dose-related trends for changes in food consumption. There were no treatment-related differences from controls in terminal body weight or gravid uterine weights. Necropsies showed no treatment-related gross pathology in any animal.

There were statistically-significant increases in absolute liver weight at 4.0 ml/kg bw/d, and relative liver weight was increased at all dosages, with mean increases of 15.5% at the high dose, 7.8% at the middle dose, and 7.8% at the low dose.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

> 3 768 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Equivalent to 4.0 ml/kg bw/d

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Increased incidence of visceral malformations and variations

Histopathological findings:

no effects observed

Details on results (F1)

Although statistically there was an increase in the incidence of total skeletal malformations on a "per litter" basis, this was considered not biologically significant because of an absence of a dose-response relationship.

There was no statistically significant increase in the incidence of total visceral malformations, but a statistically significant increase in the incidence of unilateral hydroureter, compared with the concurrent controls, was present at the high dose. There was no apparent predominance associated with the side affected. Three visceral variations were statistically significantly increased at high dose: fetal atelectasis or partial fetal atelectasis, bilateral dilated lateral cerebral ventricle, and bilateral dilated ureters. The incidences of dilated lateral ventricle and of bilateral dilated ureter were also significantly increased at the middle dose.

Thirteen skeletal variations indicating reduced ossification were statistically increased for several skeletal districts at the high dose. A reduced number of caudal segments was observed at both the high and low doses.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

There were no differences in the number of pregnancies resulting from mating as a result of treatment during gestation. There were no differences in reproductive factors or fetal body weights. This included the number of corpora lutea, % preimplantation loss, implantations, implantations per litter, viable implantations, resorptions, % live fetuses per litter, or sex ratio.

Applicant's summary and conclusion

Conclusions:

EHD, when applied dermally to the skin of rats, for a duration of 6 h/day during gestation, resulted in minor maternal toxicity but no effects on female reproductive performance or fertility. The NOEL is > 4.0 ml/kg bw/day or 3768 mg/kg bw/day.