Alcohols, C16-18

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

2-ethylhexan-1-ol is a substance supporting the category Long Chain aliphatic Alcohols within a carbon chain length range of C6-C22 and it is considered that read-across is valid.
Alcohols, C16-18 is a member and is from Long Chain Alcohols (C6-22 primary aliphatic alcohols) category.
The Long Chain Alcohols (C6-22 primary aliphatic alcohols) category is considered suitable as a source of data for Alcohols, C16-18.
Considered valid for read-across for purposes of classification.
No further vertebrate testing can be justified.

Long Chain Alcohols (C6-22 primary aliphatic alcohols) category covers a family of 30 primary aliphatic alcohols within a carbon chain length range of C6-C22. Commercial products generally include several aliphatic alcohol components, with a range of carbon chain lengths present. The family consists of alcohols with varying compositions and structures. Composition depends on the route to manufacture and the related feedstocks. Most of the alcohols have linear carbon chains but certain manufacturing processes create branched structures. Data are also available for eleven other similar substances, which support the category. Non-sponsored alcohols may not be HPV or may not be produced by members of the consortium, but have structures similar to sponsored linear alcohols.

Key points are that the members share:
• The same structural features
• Similar metabolic pathways
• Common mode of ecotoxicological action
• Common levels and mode of human health related effects.

Data source

Reference

Reference 1

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2022

Reference 2

Reference Type:

publication

Title:

The developmental toxicity of 2-ethylhexanol applied dermally to pregnant Fischer 344 rats

Author:

Tyl RW, et al.

Year:

1992

Bibliographic source:

Fund Appl Toxicol 19, 176-185.

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Remarks:

Pre-dates widespread introduction of GLP

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

IUPAC Name:

2-ethylhexan-1-ol

Details on test material:

Purity >99.7%

Test animals

Species:

rat

Strain:

Fischer 344

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kinston, NY
- Age at study initiation: 84 (m) and 67 days (f)
- Weight at study initiation: 175-200 g (m) and 130-150 g (f) on arrival
- Fasting period before study: no data
- Housing: pregnant females were housed singly
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-23
- Humidity (%): 42-65
- Air changes (per hr): no data
- 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: clipped dorsal skin, 1.5 x 1.5 inch, i.e. 9.7 cm²
- % coverage: no data
- Type of wrap if used: gauze patch, covered by a polyethylene patch. The application site was occluded with a Lycra-Spandex jacket
with Velcro closures.
- Time intervals for shavings or clipplings: no data


REMOVAL OF TEST SUBSTANCE
- Washing: no; th application site was gently wiped with moist gauze and blotted dry
- Time after start of exposure: 6 hours
TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.3, 1, and 3 ml/kg bw/day
- Concentration (if solution): undiluted
- Constant volume or concentration used: yes; based on body weight on gestational day 6
- For solids, paste formed: n.a.



USE OF RESTRAINERS FOR PREVENTING INGESTION: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The purit of the test material was examined by gas chromatography. The test material was dispensed from a 1.0 mL syringe

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: no data
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug

Duration of treatment / exposure:

gestation day (GD) 6 through 15

Frequency of treatment:

daily; 6 hours/day

Duration of test:

21 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

2 520 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

840 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

252 mg/kg bw/day

Doses / concentrations 4

Dose / conc.:

0 mg/kg bw/day

No. of animals per sex per dose:

25 females per dose group in the main test;
8 females per dose group in the preliminary test

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: based on the results of the preliminary test

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily



DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:


BODY WEIGHT: Yes / No / No data
- Time schedule for examinations:
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes / No / No data
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes / No / No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes / No / No data
- Time schedule for examinations:


POST-MORTEM EXAMINATIONS: Yes / No / No data
- Sacrifice on gestation day #
- Organs examined:

OTHER:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily



DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: before study initiation


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


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): n.a.


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): n.a.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: weights of uterus, liver, spleen, adrenals, kidneys, and thymus were recorded. Ovaries, cervices, vaginas, and thoracic and abdominal cavities were examined grossly.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes / No / No data
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other:

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: cranofacial half per litter

Statistics:

Levene's test for equal variances, ANOVA, and t-tests with Bonferroni probabilities for pairwise comparaison were used. Nonparametrid data were evaluated using the Kruskal-Wallis test followed by Mann-Whitney test when appropriate. Incidences wre compared using Fisher's exact test

Historical control data:

Not required

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Administration of 2-ethylhexanol by occluded cutaneous application to time-pregnant Fischer 344 rats during organogenesis at 0, 0.3, 1.0, or 3.0 ml/kg bw/day (25 animals per dose) resulted in maternal toxicity at 1.0 and 3.0 ml/kg/day (clinical signs of toxicity at the dosing site for both doses and reduced weight gain in the treatment period at 3.0 ml/kg/day).

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

840 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

2 520 mg/kg bw/day

Based on:

test mat.

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 was no developmental toxicity at any test dose. There was no treatment-related increased incidence of malformations

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

2 520 mg/kg bw/day

Based on:

test mat.

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

Maternal data Fate: No females died, aborted or were removed from the study. Two sham control and two low dose rats delivered early, and their data were omitted (table 1). Of the treated rats thge pregnancy rates ranged between 88 to 92%; the viability was 100% at all dose levels (table 1):

	Dose (mg/kg bw/d)
	0 (sham)	252	840	2520
Females in study	25	25	25	25
Delivered	2	2	0	0
Necropsied
- nonpregnant	3	4	2	5
- pregnant	20	19	23	20
- with only nonviable implants	2	0	0	0
- with viable fetuses	18	19	23	20
% pregnant

Clinical findings for 2 -EH treated rats were limited to lower body weight changes at the beginning of the treatment (GD 6 -9; p<0.05 in the high dose group), skin irriation (exfoliation, encrustation, and erythema, but no edema). Erythema were seen at 840 mg/kg bw/day and above. Skin irritation was generally mild, max. Draize score was 0.3 on GD14 at 1680 mg/kg bw/day in the main study. Nasal and ocular effects (encrustation and discharge) were seen with 2 -EH and sham controls. This effect was therefore not regarded to be treatment-related. Necropsy findings: Residual exfoliation and crusting at the application site in mid- and high-dose 2 -EH groups were the only treatment-related findings; i.e. body weight, gravid uterus weight, and organ weights were all comparable to the controls. Gestational parameters: 2 -EH was without adverse effect, at any treatment level, compared with controls (table 2):

 

	Dose levels (mg/kg bw/day)
	0 (sham)	252	840	2520
No. pregnant dams	11.6(a)	10.4	11.3	10.8
Corpora lutea /dam	16.0	15.4	15.7	15.3
Total implants	5.9	6.7	8.3	7.4
Viable implants	4.24	4.36	3.96	3.2
Nonviable implants	0.4	0.2	0.1	0.1
Early resorptions	0.4	0.2	0.1	0.1
Late resorptions	0	0	0	0
Dead fetuses	0	0	0.1	0
Percentage of live fetuses	86	96.8	97.8	99
Sex ratio (% males)	62.8	41.8	43.7	53.4
Fetal body weight (g)	4.59	4.51	4.4	4.5

(a)n = 18 Fetal data Fetal body weight was not affected at any dose level (table 2).

The incidence and the pattern of malformations or variations was not changed in treated rats compared to controls (table 3):

	Dose levels (mg/kg bw/day)
	0 (sham)	252	840	2520
External malformationsNumber with malformations/Number examined	0/110	0/124	0/185	0/147
%	0	0	0	0
Soft tissue malformationsNumber with malformations /Number examined	0/110	0/124	0/185	0/147
%	0	0	0	0
Skeletal malformationsNumber with malformations /Number examined	0/110	0/124	0/185	0/147
%	0	0	0	0
External variationsNumber with variations/Number examined	13/110	19/124	37/185	21/147
%	11.8	15.3	20	14.3
Soft tissue variationsNumber with variations/Number examined	30/63	36/66	57/97	42/79
%	47.6	54.5	58.8	53.2
Skeletal variationsNumber with variations/Number examined	53/53	88/88	68/68	31/31
%	100	100	100	100

Applicant's summary and conclusion

Conclusions:

No developmental toxicity by dermal route noted at and below dose levels producing maternal toxicity.
2-ethylhexan-1-ol is a substance supporting the category Long Chain aliphatic Alcohols within a carbon chain length range of C6-C22 and it is considered that read-across is valid.

Executive summary:

The developmental toxicity of 2 -EH following dermal absorption was examined in a OECD TG 414 rat study that was conducted under GLP. 2 -EH was applied to the skin of 25 females at 252, 840, and 2520 mg/kg bw/day under an occlusive dressing during gestational days 6 -15 for 6 hours per day. The dose levels were selected based on the results of a preliminary study (Tyl et al., 1992).

The maternal toxicity was mild. There were no deaths or severe clinical signs of toxicity. A reduced body weight gain in high-dose rats was noted, and local skin irritation in rats at the intermediate and the high dose level.

2 -EH had no adverse effect on the maternal gestational parameters, or maternal organ weights, or on the fetal weight, sex ratio, viability, or the incidence of malformations and variations.

Therefore, the NOAEL for maternal systemic toxicity was 840 mg/kg bw/day, based on the effects on body weight gain; the NOAEL for skin irritation was 252 mg/kg bw/day. The NOAEL for developmental toxicity and teratogenicity was 2520 mg/kg bw/day.

2-ethylhexan-1-ol is a substance supporting the category Long Chain aliphatic Alcohols within a carbon chain length range of C6-C22 and it is considered that read-across is valid.