Bis(ethyl acetoacetato-O1',O3)bis(2-methylpropan-1-olato)titanium

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:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was performed according to the OECD guideline (1981) , prenatal toxicity study. Read-across justification: The substance is hydrolytically unstable. When it comes in contact with water or moisture complete hydrolysis will take place with no significant reaction products other than alcohols, ethyl acetoacetate and hydrated titanium dioxide. The half-life of hydrolysis is < 10 minutes @ 25 ˚C. This rapid hydrolysis is the driving force for the toxicokinetics of target substance. Because of the rapid hydrolysis, the influence of the mode of administration through inhalation, dermal and oral is related to the most hazardous degradation products released from the target substance. In addition, because of rapid hydrolysis the dermal effects of the target substance are similar to the irritating properties of the degradation products. The identification of degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the mixture of particular alcohol and ethyl acetoacetate which might change the hazardous properties of the target substance compared to the properties of the pure alcohol and ethyl acetoacetate. As there is a mechanistic reasoning to the read-across, the unnecessary animal testing is avoided by using the read-across from the most hazardous degradation products (alcohols) to evaluate irritation, sensitization and the short-term and long-term toxicological effects of the target substance.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1995

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Principles of method if other than guideline:

Pregnant rats (25/group) were exposed to 2-methylpropanol by whole body inhalation from gestation day 6 thru 15. Body weights, feed consumption, and clinical sign data were collected throughout the study.

Pregnant rabbits (15/group) were exposed to 2-methylpropanol by whole body inhalation from gestation day 7 thru 19. Body weights, feed consumption, and clinical sign data were collected throughout the study.

GLP compliance:

yes

Remarks:

The testing laboratory was not mentioned in the publication.

Test material

Test material information

Constituent 1

Reference substance name:

2-methylpropan-1-ol

EC Number:

201-148-0

EC Name:

2-methylpropan-1-ol

Cas Number:

78-83-1

Molecular formula:

C4H10O

IUPAC Name:

2-methylpropan-1-ol

Test material form:

other: vapor

Details on test material:

- Name of test material (as cited in study report): 2-methyl 1-propanol
- Physical state:
- Analytical purity: 99.8%
- Storage condition of test material: Test material have been proved to be stable atleast 6 months

Test animals

Species:

other: Rats and Rabbit

Strain:

other: Wistar rats and Himalayan rabbits

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr. K. Thomae GmbH, Biberach/Riss, Germany
- Age at study initiation:10-11 weeks for rat and 24-29 weeks for rabbit
- Weight at study initiation: 216 g for rat, 2.5-2.7 kg for rabbit
- Fasting period before study:
- Housing: housed individually in wire cages in air conditioned room
- Diet (e.g. ad libitum): laboratory diet 24-343-4, 10 mm pallates, (Klingentalmuhle AG, Kaiseraugst Switzerland)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

air

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Glass inhalation exposure chamber


- Temperature, humidity, in air chamber: 21-24 ̊C and 49-64% respectively
- Air change rate: 15 air per changes

TEST ATMOSPHERE
- Brief description of analytical method used: Samples from inhalation atmoshphere were analyzed hourly by gas chromatography (Hewlett -Packard gas chromatograph model 5840 A with automated sampler model 7671 A, FID)
- Samples taken from breathing zone: yes/no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The analysis of daily inhalation chamber concentration resulted in chamber value (mean±SD) detected by gas chromatography. (see picture below)

Details on mating procedure:

- Impregnation procedure: artificial insemination for rabbit, cohoused for rats
- If cohoused: vaginal smear method for rats
- M/F ratio per cage: 1/4
- Proof of pregnancy:for rats sperm in vaginal smear referred to as day 0 and following days defined as Day 1 post coitum and for rabbits the day of insemination defined as day 0 and folllowing days as postinsemination of pregnancy

Duration of treatment / exposure:

6 hrs/day

Frequency of treatment:

rats were exposed on day 6-15 post coitum and rabbits were exposed to day 6-15 post-insemination.

No. of animals per sex per dose:

25 female rats and 15 female rabbits/ group

Control animals:

yes, concurrent no treatment

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:daily

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

BODY WEIGHT: Yes
- Time schedule for examinations: for rat weighted on day0, 3, and 6 and rabbits weighted on day 0,3, and 7 and from then on 3 day intervals until day 20 postcoitum and day 29 postinsemination respectively .

- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

:

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # day 20 postcoitum for rats and day 29 postinsemination for rabbits.
- Organs examined: uterine weight, number of corpora lutea, number of implants, pre and post implantation losses were calculated

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

Fetal examinations:

- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes

Statistics:

Dunnett test was used to statistically compare body weight, body weight changes, corrected body weight, intact uterine weight, the number of corpora leutea, implants, resorptions, live fetuses and pre or post implantation losses. The fisher exact test was used for evaluating the conception rate, maternal mortality and all fetal findings.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes. Remark: A slight (nonsignificant) retardation in body weight was observed in rabbits of the highdose group throughout the exposure period. Otherwise, no compoundrelated effects indicative of maternal toxicity were found.

Details on maternal toxic effects:
There was no influence of inhalation on body weight changes in both rats and rabbits at 0.5 and 2.5 mg/liter, but in rabbits exposed to higher level (10 mg/liter) a slight retardation in body weight increase, through out the whole exposure (See in picture below) . Analysis of reproduction data for all groups of rabbit and rats neither show compound related toxic effects for conception rate, mean number of corpora lutea, and implantation sites nor in values calculated for the pre and postimplantation loss and the number of resorptions as well as viable fetuses.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEC

Remarks:

(rabbits)

Effect level:

2 510 mg/m³ air

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEC

Remarks:

(rabbits)

Effect level:

10 000 mg/m³ air

Basis for effect level:

other: developmental toxicity

3

Dose descriptor:

NOAEC

Remarks:

(rats)

Effect level:

10 000 mg/m³ air

Basis for effect level:

other: maternal toxicity

4

Dose descriptor:

NOAEC

Remarks:

(rats)

Effect level:

10 000 mg/m³ air

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The mean placental and fetal weights ant also sex distribution were not affected by treatment of dams of either sexes. Examination of fetuses for external malformations, soft tissue changes and skeletal examination revealed various malformation but difference was not in concentration related manner and was not statistically significant. .

Effect levels (fetuses)

1

Dose descriptor:

NOAEC

Remarks:

(rabbits)

Effect level:

10 000 mg/m³ air

Basis for effect level:

other: teratogenicity

2

Dose descriptor:

NOAEC

Remarks:

(rats)

Effect level:

10 000 mg/m³ air

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

Read-across justifications and data matrices are presented in IUCLID section 13.

Applicant's summary and conclusion

Conclusions:

Developmental toxicity / teratogenicity of 2-methylpropanol was investigated in rats and rabbits. For rats, NOAEL maternal toxicity and NOAEL developmental toxicity was 10 mg/l. For rabbits, NOAEL maternal toxicity was 2.51 mg/l and NOAEL developmental toxicity was 10 mg/l.

Executive summary:

Rats:

No treatment related effects on either the dams or the offspring were observed. Therefore, compound-induced embryo- or fetotoxic effects could not be detected under the conditions of this study, including the highest concentration of 10 mg/l 2-methylpropanol. Furthermore, teratogenic effects were also not induced by this substance.

Rabbits:

Each control and study group contained 15 pregnant females. A slight (non significant) retardation in body weight was observed in rabbits of the high dose group throughout the exposure period. Otherwise, no compound related effects indicative of maternal toxicity were found. Significantly increased incidences of intraventricular foramen/septum membranaceum (variations in cardiac septal development) were found for the high-dose group. This is a very common variation in rabbits. The litter incidence in this study was 13.3 %, 7.1 %, 0 %, and 38.5 % in the control, low, mid and high exposure groups, respectively. This finding was not considered to be of biological significance, because with the litter historical control range for this variation was from 0 to 47 %. Therefore, the incidence in the high exposure group was found to be within the normal range of biological variation for this strain of rabbit. Substance related effects on the offspring, indicative of embryo-/fetotoxicity or teratogenicity, were not observed. The differences evident were considered to be incidental and within range of variation known for these strains and ages of both animal species when compared with historical control.