Distillation residue, butyl alcohols production, rectification

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

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 target UVCB-substance, 2-ethylhexanol. Studies performed with pregnant Fischer F344 rats and they study the developmental toxicity of 2-ethylhexanol. In the absence of data on the target UVCB-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 target 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. d) This target substance is classified as skin irritant, based on its use and exposure scenarios a repeated exposure via dermal route cannot be expected since first contact to skin will exert irritating effects. e) no further vertebrate testing should not be commenced since based on the expected exposure based on the uses of this UVCB-substance to human, dermal route exposure is not expected to be continuous therefore chronic effect levels are sufficient to meet the safe handling of this substance and adopted risk management measures based on its irritant properties are enough (chapter 9 and 10 of CSR).

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

Remarks:

does not follow guidelines but represents similar type of approach.

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

Type of coverage:

occlusive

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.

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:
analytical per unit body weight

Doses / concentrations 2

Remarks:

Doses / Concentrations:
420 mg/kg bw day
Basis:
analytical per unit body weight

Doses / concentrations 3

Remarks:

Doses / Concentrations:
840 mg/kg bw day
Basis:
analytical per unit body weight

Doses / concentrations 4

Remarks:

Doses / Concentrations:
1680 mg/kg bw day
Basis:
analytical per unit body weight

Doses / concentrations 5

Remarks:

Doses / Concentrations:
2520 mg/kg bw day
Basis:
analytical per unit body weight

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: 2-methoxyethanol, positive control... (see attached file)

Details on study design:

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

Positive control:

2-methoxyethanol (undiluted, dermal route) and valproic acid (2ml cavage).

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: daily, after each 6-hour treatment period. Irritation was scored according to FHSA standard.

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

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, 3-day interval from GDS 0 thorugh 21.

FOOD EFFICIENCY: No data

WATER CONSUMPTION: No data

Sacrifice and pathology:

MATERNAL AND FETAL OBSERVATIONS AT NECROPSY
- females which delivered early were terminated, examined grossly, and removed from the study. Surviving females from both studies were euthanized with CO2 asphyxiation on day 21. Maternal body cavities were opened by midline thoracolaporotomy. Maternal uterine and liver weights (both studies) and spleen, adrenals, kidneys, and thymus weights (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 contents. All live and dead fetuses and resorption sites were noted; uteri from nongravid females were tested for early resorptions with ammonium sulfide solution.

MALFORMATIONS AND VARIATIONS

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 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 of examinations

Clinical signs:

no effects observed

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Observed daily, measured before and after 6-h treatment period. 252 mg/kg bw/day, suitable as DNEL.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

1680 and 2520 mg/kg bw/day groups reduced weight gain.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

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.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

female

Basis for effect level:

other: clinical signs: skin irritation

2

Dose descriptor:

NOAEL

Effect level:

> 840 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: Reduced weight gain with doses 1680 (range-finding study) and 2520 (main study) mg/kg bw/day

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Repeated dermal exposure of 2-ethylhexanol lead with high doses (1680 and 2520 mg/kg bw/day) to slight reduction in body weight. otherwise It did not indicate properties which would lead to a concern for toxicity via dermal route. Tthere was no exacerbation by continuent treatment. Erythema subsided immediately after cessation of treatment. The only effect was mild skin irritation.