Distillation residue, butyl alcohols production, rectification

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Repeated-dose dermal toxicity, similar to that of OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test), studies performed with the only identified and quantified constituent of the registered substance, 2-ethylhexanol. Studies performed with pregnant Fischer F344 rats and they study the developmental toxicity of 2-ethylhexanol. In the absence of the registered substance these studies serve as a good surrogate studies: a) it represents the effects of the only identified and quantified consituent of the substance, since the consituents of this registered UVCB-substance cannot be recognized and its composition varies to the degree that composition cannot be fixed. b) studies have been performed with good quality and data is published in a peer-reviewed journal. c) they provide adequate information on effect levels of 2-ethylhexanol when administered via dermal route.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Principles of method if other than guideline:

Pregnant Fischer 344 rats were studied in two studies with an occluded dermal application:
1. Range-finding study
2. Main study

GLP compliance:

yes

Remarks:

U.S EPA Health effects guidelines and Good Laboratory Practice regulations.

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexan-1-ol

EC Number:

203-234-3

EC Name:

2-ethylhexan-1-ol

Cas Number:

104-76-7

Molecular formula:

C8H18O

Details on test material:

Surrogate material: 2-ethylhexanol.
Test substance - 2-ethylhexanol: 99,72% purity, gas chromatographic verification by the contract laboratory. (sample provided by the Shell developmental company, Houston, TX, USA).
Control substances: 2-methoxyethanol (dermal reference) and valproic acid (cavage reference) had purities of 99,9% and 98,0%, respectively.

Test animals

Species:

rat

Strain:

Fischer 344

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Virgin F344 rats (CDF(R) F344 Crl./Br.)
- Source: Charles River Breeding Laboratories (Kingston, NY)
- Age at study initiation: 70 days / 63 days
- Weight at study initiation: males 175-200g / females 130-150g
- Gestational day 0: appearance of copulatory plug
- Housing: singly
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 2-week quarantine period

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 42-65
- Air changes (per hr): not disclosed
- Photoperiod (hrs dark / hrs light): 12 hour

Administration / exposure

Route of administration:

dermal

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: clipped and shaved dorsal skin of 9,7 cm2 (in the report ca. 1,5 cupic inches)
- Type of wrap if used:2 cupic inch gauze square, occluded with a Lycra-Spandex with Velcro closures. A 1.5x2.5 in. polyethylene patch was attached at the application site under the jacket.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): wiped gently with moist gauze and blotted dry.
- Time after start of exposure: 6-hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):
1.Rangefinding study: 0.5, 1, 2, 3 (ml/kg/day) equivalent to 420, 840, 1680, 2520 (mg/kg/day). Positive control: 2-methoxyethanol: 0.5 and 1.5 (ml/kg/day) equivalent to 420 and 1260 (mg/kg/day). Oral cavage reference compound: Valproic acid 400 mg/kg bw/day.
2. Main study: 0.3, 1, 3 (ml/kg/day) equivalent to 252, 840, 2520 (mg/kg/day).Positive control: 2-methoxyethanol 1 (ml/kg/day) equivalent to 840 (mg/kg/day)
- Concentration (if solution): 100%
- Constant volume or concentration used: no


VEHICLE
- No vehicle

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Gas chromatographic: at the beginning of the studies and in the end of the studies. Test material was verified to be stable over the treatment periods.

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: not disclosed
- Proof of pregnancy:[vaginal plug referred to as day 0 of pregnancy: "Gestational day 0: appearance of copulatory plug"

Duration of treatment / exposure:

6-hours per day

Frequency of treatment:

daily

Duration of test:

21 days, exposure to test substance between gestational days 6 to 15.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
252 mg/kg bw/day
Basis:
other: analytical per unit bodyweight

Doses / concentrations 2

Remarks:

Doses / Concentrations:
420 mg/kg bw/day
Basis:
other: analytical per unit bodyweight

Doses / concentrations 3

Remarks:

Doses / Concentrations:
840 mg/kg bw/day
Basis:
other: analytical per unit bodyweight

Doses / concentrations 4

Remarks:

Doses / Concentrations:
1680 mg/kg bw/day
Basis:
other: analytical per unit bodyweight

Doses / concentrations 5

Remarks:

Doses / Concentrations:
2520 mg/kg bw/day
Basis:
other: analytical per unit bodyweight

No. of animals per sex per dose:

Pregnant Fischer 344 rats were studied in two studies with an occluded dermal application:
1. Range-finding study: 8 animals per group
2. Main study: 25 animals per group

Litters: number examined Sham (110), 252 mg/kg (124), 840 mg/kg (185), 2520 (147), and 2-methoxyethanol (68).

Control animals:

yes, sham-exposed

other: Positive control, dermal route: 2-methoxyethanol... (see attached file)

Details on study design:

- Dose selection rationale: range-finding study performed
- Rationale for animal assignment (if not random): random

Examinations

Maternal examinations:

Pregnant females were sacrificed on gestational day 21 by euthanization with CO2 asphyxiation. Maternal body cavities were opened by midline thoracolaporotomy. Maternal uterine weights and liver weights (both studies) and spleen, adrenals, kidneys, and thymus weighs (main study) were recorded. CAGE SIDE OBSERVATIONS: Yes, time schedule: daily, before and after treatment. Draize-score represented.
Estrous cyclicity not disclosed, animals were deemed suitable after fecal sampling, histological testing of selected organs, and serum viral antibody testing examination. After a 2-week quarantine period animals were mated 1:1.

Ovaries and uterine content:

Corpora lutea and uterine implantation sites were counted, and ovaries cervices, vaginas, and abdominal and thoracic cavities were examined grossly. Uteri were examined externally, removed, and dissected longitudinally to expose the contents. All live and dead fetuses and resorption sites were noted,; uteri from nongravid females were tested for early resorptions with ammonium sulfide solution.

Fetal examinations:

All live fetuses were sexed, weighed, and examined for external malformations and for variations. After external examination approximately 50% of the live fetuses per litter from the main study were examined for visceral (thoracic and abdominal) and craniofacial abnormalities. The remainder were examined for skeletal malformations and variations after evisceration, fixation in ethanol, and staining with alizarin red S.

Statistics:

The units of comparison were pregnant rat or the litter. Quantitative continuous variables such as maternal body and organ weights were compared to 2-ethylhexanol and sham control groups, between dermal reference (2-methoxyethanol) and sham control groups, and between cavage reference and naive control group. Levene's test for equal variances, ANOVA, and t-tests with Bonferroni probabilities for pairwise comparisons were used. The pooled t-test was used when Levene's test indicated homogeneous variances, all groups were compared by an ANOVA for unequal variances followed when necessary by the separate variance t-test.

Historical control data:

Not disclosed, but similar studies and results with Wistar and Sprague-Dawley rats referred. 2-methoxyethanol and Valproic acid were therefore used as reference material. Strain sensitivity was esteablished by the maternal toxicity, post-implantation loss, and reduced fetal body weights produced by daily cavage doses of valproic acid 400 mg/kg bw/day, as well as external and visceral fetal malformations.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes. Remark: NOAEL 840 mg/kg bw/day

Details on maternal toxic effects:
Reduced weight gain with doses 1680 (range-finding study) and 2520 (main study) mg/kg bw/day. Skin irritation at 252 mg/kg bw/day.

DERMAL IRRITATION
Treatment -related effects attributable to 2-ethylhexanol at the application site were exfoliation, encrustation and erythema. There was no edema. Exfoliation and encrustation occurred in both range-finding and main studies at all treatment levels of 2-ethylhexanol. There was no erythema or edema in sham controls. Erythema occurred during treatment with 2-ethylhexanol at levels of 830 mg/kg bw/day and above. Draize scores revealed that irritation was essentially mild. Maximum mean treatment scores occurred on gd10 at 1680 mg/kg bw/day (draize-score 0.4, range-finding study), on gd 11 at 2520 mg/kg bw/day (draize-score 1.1, range-finding study), and on gd 14 at 1680 mg/kg bw/day (draize-score 0.3, main study).

There was no exacerbation by continuent treatment. Erythema subsided immediately after cessation of treatment. There was no exfoliation, encrustation, erythema or edema at the application of positive control, 2-methoxyethanol.

Nasal encrustation and ocula encrustation and discharge were seen mostly in the main study with 2-ethylhexanol and 2-methoxyethanol and in sham controls. Since these effects occurred in controls and mostly disappeared after treatment ceased they are attributed to handling stress.

NOAEL was set at 252 mg/kg bw/day based on skin irritation property, described by draize score on parental animals.

CLINICAL SIGNS
Reduced body weight with 1680 mg/kg bw/day (range-finding study) and 2520 mg/kg bw/day (main study), NOAEL was determined to be 840 mg/kg bw/day.

Other effects were not found: gravid uterine weight, early deliveries, pregnancies, fetus viability , early resorptions, and late resorptions.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

>= 252 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: other:

2

Dose descriptor:

NOAEL

Effect level:

> 2 520 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
Gestational parameters: In both studies, all treatment levels 2-ethylhexanol was without any adverse effect, compared with controls, on total and non-viable implants, early and late resorptions. Fetal malformations and variations: there were no external, visceral or skeletal malformations associated with any treatment level of 2-ethylhexanol.

There were no effects found external examination of the live fetuses per litter from the main study, which were examined for visceral (thoracic and abdominal) and craniofacial abnormalities. Also, skeletal malformations and variations after evisceration, sex ratio, fetal body weight were unchanged between the controls and different treatment groups.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Developmental and teratogenic toxicity was determined in this dermal screening test with 2-ethylhexanol, besides reduction of body weight in highest doses and mild skin irritation in all doses, 2-ethylhexanol did not exhibit toxicity to fetuses and risk to pregnancy. Both effects (reduced body weight, skin irritation) occurred during treatment and were transient or ameliorated after treatment ceased. This study includes approriate sham controls and reference compound via oral cavage. There were no effects on gestational parameters and no significant differences from controls in the incidence of fetal malformations and soft tissue or skeletal variations.