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

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

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 conducted in compliance with GLP but guideline followed was not mentioned. 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:

Neurotoxicity evaluation of rats after subchronic inhalation exposure to isobutanol

Author:

Li, A.A., Thake, D.C., Kaempfe, T.A., Branch, D.K., O’Donnell, P., Speck, F.L., Tyler, T.R., Faber, W.D., Jasti, S.L., Ouellette, R., and M.I. Banton

Year:

1999

Bibliographic source:

Neurotoxicology, vol 20(6) PN. 889-900

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

No details are provided in the reference concerning the method employed.

GLP compliance:

no

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: liquid

Details on test material:

- Name of test material (as cited in study report): Isobutanol
- Analytical purity: 99%

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:Charles river laboratories, Inc.;raleigh,NC
- Age at study initiation:8 weeks
- Weight at study initiation:285-365 g males, 170-242 g females
- Fasting period before study:

- Diet (e.g. ad libitum): purina mills rodent chow #5002
- Water (e.g. ad libitum):ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C):18-26
- Humidity (%):30-70%
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):12 hrs

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

other: glass hazelton H-2000 chamber

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:glass hazelton H-2000 chamber
- Temperature, humidity,in air chamber: 23-24 ̊C, 48-53 % respectively
- Air flow rate: 500 liter/min
- Air change rate: 15 air changes /min



TEST ATMOSPHERE
- Brief description of analytical method used: isobutanol vapor were determined by drawing test atmosphere samples from animals breathing zoneat evenly spaced interval (18 sample per exposure) through Fourier transform infrared analyzer (FVB/analect, Irvine, CA)

- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The mean (±SD) isobutanol chamber concentration were 258 (±8), 1044(±34), and 2548 (±58) ppm for the duration of the subchronic neurotoxicity study. The respective nominal to analytical ratio were .97, .95 and .97. For SCOB ( Schedule controlled operant behavior ) study isobutanol chamber concentration were 258 (±9), 1045(±35), and 2557 (±60) ppm and the nominal to analytical ratio were .97,.96 and .97 respectively.

Duration of treatment / exposure:

14 weeks with the exception that the animals were not exposed one day during 4th, 8th and 13th week of exposure when animals were subjected to neuro behavioral study. Each rats received at least 70 exposures.

Frequency of treatment:

6hrs/day

Doses / concentrations

Remarks:

Doses / Concentrations:
0,250,1000,2500 ppm
Basis:
no data

No. of animals per sex per dose:

15 animals per group per sex (both male and female) for neurotoxicity study (Total 120 animals)
10 male SD rats per group for SCOB (Schedule controlled operant behavior) study (total 40 rats)

Control animals:

yes

Positive control:

Positive control group study (with amphetamine SO4 and chlorlpromazine) was conducted with separate groups of rats (4 group of 10 male SD rats each) prior to this study to demonstrate 4FR20/2FI120 multiple schedule of reinforcement generates response rate.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:Twice a day

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: during 14th exposure week in neurotoxicity study
- Dose groups that were examined: control and highest dose group(2500 ppm)

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the termination of study
- Anaesthetic used for blood collection: Yes (CO2)
- Animals fasted: Yes (overnight)
- How many animals: 5 rats/sex/exposure group
.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood:at the termination of study
- Animals fasted: Yes
- How many animals:5 rats/sex/exposure group

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: prior to exposure and then on 4th, 8th, 13th weeks of exposure
- Dose groups that were examined: all groups
- Battery of functions tested: Functional observation battery (FOB) and motor activity

OTHER:

Sacrifice and pathology:

HISTOPATHOLOGY: Yes

Other examinations:

Behavioral test consist of Functional observation battery (FOB) and an automated test for motor activity. FOB test include observation to degree of lacrimation, salivation, presence of exopthalmia, degree of palpebral opening, presence or absence of piloerection and any general descriptive clinical effects were noted. Motor activity was measured by automated photo cell recording apparatus designed to measure activity in the novel enviroment.

Statistics:

Total motor activity and SCOB(Schedule controlled operant behavior) dependent variables were analyzed as mean weekly percent of protest values at each time point using Dunnetts 2 sided comparision of treatment and control and Levene's test for homogencity of variance. In addition two factor repeated measure analysis of co-variance (REPANCOVA) used for motor and SCOB dependent variable.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

There were no treatment related abnormal clinical sign seen after exposure to any concentration

Mortality:

mortality observed, treatment-related

Description (incidence):

There were no treatment related abnormal clinical sign seen after exposure to any concentration

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There were no treatment related significant changes in body weight and cumulative body weight were seen after exposure to any concentration

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

There were no treatment related significant food consumption changes were seen at any dose

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

effects observed, treatment-related

Description (incidence and severity):

No occular abnormalities noted at 2500 ppm and control exposure levels.

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

There were slight increases in RBC, heamatocrit value and heamoglobin parameters in 2500 ppm females that were statistically significant.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

There were increase in serum calcium level in the males at 100 ppm significantly but that was not in dose related fashion, so can not be considered as a consequence of isobutanol exposure.

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

There were no significant concentration time interaction in any behavioral parameters as determined by repeated measures analysis of covariance

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

there were no significant difference in terminal absolute organ weight, organ to body weight ratio, or organ to brain weight ratio for any group or for any tisssue.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

There were no treatment related gross or microscopic abnormalities noted in any of the tissue

Details on results:

Ther were no significant effects of isobutanol exposure to all concentration were observed for clinical signs and mortality, body weight and weight gain, organ weights, food consumption, food efficiency, water consumption, ophthalmoscopic examination.
HAEMATOLOGY: There were slight increases in RBC, heamatocrit value and heamoglobin parameters in 2500 ppm females that were statistically significant.(see picture below)
NEUROBEHAVIOUR : During SCOB (Schedule controlled operant behavior) analysis FR post-reinforcement pause (PSAP), FR running rate, FI response rate, FI Index of curvature (IOC) were determined. There were no statistically significant effects between treated and control groups for any SCOB parameters. (see picutre below)

Effect levels

Dose descriptor:

NOAEC

Effect level:

3 030 mg/m³ air

Based on:

test mat.

Sex:

female

Basis for effect level:

other: There were slight increases in RBC, heamatocrit value and heamoglobin parameters in 2500 ppm females that were statistically significant. Thus, the NOAEC of this substance is 1000 ppm (3030 mg/m3)

Target system / organ toxicity

Critical 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:

The study consisted of male and female ad libitum-fed Sprague-Dawley(SD) rats designated for functional observational battery, motor activity, and
neuropathology endpoints. Groups consisted of 20, 10, 10, and 20 rats/sex for the 0, 250, 1000, and 2500 ppm groups, respectively. Based on the study results the NOAEL of 1000 ppm (3030 mg/m3) was established.

Executive summary:

There were no morphological of behavioural effects indicative of a persistent or progressive effect of 2 -methylproanol on the nervous system at exposure concentrations of up to 2500 ppm. A slight reduction in responsiveness to external stimuli occurred in all treated groups during exposure. However, there was no difference from the control animals with respect to responsiveness during nonexposure periods. No effects were noted during the FOB examinations. Therefore, the slight decrease in responsiveness are likely transient effects from acute exposure to 2 -methylpropanol. There was a slight (but statistically significant) increase in red blood cell counts, hematocrit, and hemoglobin parameters in the 2500 ppm female rats when compared to the control female rats. Although these effects were considered related to treatment and considered for the derivation of the NOAEL, they were of questionable biological significance

due to the slight nature of the effects. There were no changes in ophthalmology, serum chemistry, organ weights, or gross or microscopic

pathology that were attributed to 2 -methylpropanol exposure.