Distillation residue, butyl alcohols production, rectification

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

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

Adequacy of study:

key study

Study period:

1992-03-05

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 studies conducted for registered substance these studies serve as a good surrogate studies.

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:

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

Sex:

female

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

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"

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.

Duration of treatment / exposure:

6-hours per day

Frequency of treatment:

daily

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:

Range-finding study: 8 animals per study group
Main study: 25 animals per study group

Control animals:

yes, sham-exposed

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

Details on study design:

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

Positive control:

Dermal route, positive control: 2-methoxyethanol, oral reference (cavage): Valproic acid

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily, before and after treatment. Draize-score represented.

CLINICAL SIGNS
- Time schedule: daily and skin irritation (scored based on FHSA, 1985).

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights on gestational days 0, 6,9, 12, 15 and 21.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, 3-day intervals, through destational days 0-21.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data

Oestrous cyclicity (parental animals):

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.

Sperm parameters (parental animals):

Not disclosed.

Litter observations:

All live fetuses were sexed, weighed, and examined for external malformations and for variations.

Postmortem examinations (parental animals):

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. 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.

Postmortem examinations (offspring):

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.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

skin irritation >252 mg/kg bw/day

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

body weight reduction >840 mg/kg bw/day

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

body weight reduction >840 mg/kg bw/day

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

not examined

Details on results (P0)

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 (P0)

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

female

Basis for effect level:

other: see 'Remark'

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

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:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

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.

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Overall reproductive toxicity

Reproductive 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 (reduction of 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.