Tetra-n-butyl titanate, polymer with water

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Link to relevant study records

Reference

Endpoint:

extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)

Type of 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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Meets generally accepted scientific standards, well documented and acceptable for assessment. 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 alcohol and hydrated titanium dioxide. This rapid hydrolysis (hydrolysis half-life < 3 minutes to < 2 hours) 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 hazardous degradation product (alcohol) released from the target substance. The identification of degradation products from the hydrolysis study conducted for the target substance verifies that there are no impurities in the alcohol released from the target substance, which might change the hazardous properties of the target substance compared to the properties of the pure alcohol. As there is a mechanistic reasoning to the read-across, the unnecessary animal testing is avoided by using the read-across data from the degradation product (relevant alcohol) to evaluate irritation, sensitization and the short term and long-term toxicological effects and mutagenicity of the target substance.

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

Two concentrations of butan-1-ol (3000 and 6000 ppm) were administered by inhalation to separate groups of 15 pregnant Sprague-Dawley rats for 7 hr per day throughout gestation ; 18 male rats were similarly exposed for 7 hr per day for 6 weeks, and mated to unexposed females.

GLP compliance:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: (P) Males: mean: 429-512 g; Females: mean: no data


ENVIRONMENTAL CONDITIONS
no data

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

not specified

Vehicle:

air

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations measured in the exposure chambers approximated the target concentrations of 3000 and 6000 ppm. Mean (±s.d.) 1-butanol concentrations were 3010 (±50) and 6000 (±80) ppm, and results of periodic confirmatory charcoal tube samples were 3000 (± 90) and 5960 (± 110) ppm, respectively .

Duration of treatment / exposure:

females: Exposure period: day 1 - 20 of gestation
males: 6 weeks before mating

Frequency of treatment:

7 h/d

Remarks:

Doses / Concentrations:
0, 3 000, 6 000 ppm
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
0, 9 250, 18 500 mg/m3 air
Basis:
nominal conc.

No. of animals per sex per dose:

15 females per dose
18 males per dose

Control animals:

yes

Statistics:

Data were analyzed using multivariate analysis of variance (MANOVA) on tests with multiple dependent measures, followed by analysis of variance (ANOVA) on each dependent variable if a significant MANOVA was observed. If only one dependent variable was obtained, ANOVA was used, followed by the Tukey Range Test to determine which cell means differed from one another.

Dose descriptor:

NOAEC

Effect level:

18 500 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Pregnancy rate

Dose descriptor:

NOAEC

Generation:

F1

Effect level:

18 500 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Developmental neurotoxicity

Reproductive effects observed:

not specified

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

Conclusions:

Female rats exposed to 6 000 ppm (18 500 mg/m3) n-butanol throughout gestation and male rats exposed to 6 000 ppm (18 500 mg/m3) n-butanol for six weeks prior to mating showed no effects on fertility or pregnancy rate.

Executive summary:

In a reliable developmental neurotoxicity study groups of 18 male Sprague-Dawley rats were exposed to concentrations of 0, 3000, or 6 000 ppm n-butanol for 7 hours/day for 6 weeks. These males were then mated to non-exposed female rats of the same strain. In a separate experiment, groups of 15 pregnant female rats were exposed to concentrations of 0, 3 000, or 6 000 ppm for 7 hours/day from gestation Day 1-20. These females were then allowed to deliver. The offspring from these two groups were then observed for signs of developmental neurotoxic effects. Offspring were examined from postnatal days 10-90 for the following measures: ascent on a wire mesh screen, rotorod, open-field and photoelectrically-monitored activity, running wheel, avoidance conditioning, operant conditioning. Acetylcholine, dopamine, norepinephrine, serotonin, met-enkephalin, beta-endorphin and substance P neurotransmitter levels were measured from the cerebrum, cerebellum, brainstem, and midbrain.

No detectable effect on pregnancy rate was found after either maternal or paternal exposure. In the 6 000 ppm (18 500 mg/m3) group, 4 of the 78 (5%) behavioral measures, and 4 of the 64 (6%) neurochemical measures differed from those of controls. However, no dose-response correlation was observed. Thus, the NOAEL for the P and F1 generation is 18 500 mg/m3.

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

18 500 mg/m³

Study duration:

subacute

Species:

rat

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

There is no reproductive toxicity study available for the substance itself. Instead, relevant data from the degradation products is used to assess the reproductive toxicity of tetra-n-butyl titanate, polymer with water. Read-across data from n-butanol and titanium dioxide (TiO2) is used for assessment, because the target substance is hydrolytically unstable having the half-life less than 2 hours (Brekelmans, M. J. C., 2013). Based on the rapid hydrolysis, the intrinsic properties are most likely related to these two decomposition products, n-butanol being the most relevant decomposition product for CSA. Since n-butanol is a volatile substance, the most relevant route for human exposure is inhalation.

In a reliable developmental neurotoxicity study groups of 18 male Sprague-Dawley rats were exposed to concentrations of 0, 3000, or 6000 ppm n-butanol for 7 hours/day for 6 weeks. These males were then mated to non-exposed female rats of the same strain. In a separate experiment, groups of 15 pregnant female rats were exposed to concentrations of 0, 3000, or 6000 ppm for 7 hours/day from gestation Day 1-20. These females were then allowed to deliver. The offspring from these two groups were then observed for signs of developmental neurotoxic effects. Offspring were examined from postnatal days 10-90 for the following measures: ascent on a wire mesh screen, rotarod, open-field and photoelectrically-monitored activity, running wheel, avoidance conditioning, operant conditioning. Acetylcholine, dopamine, norepinephrine, serotonin, met-enkephalin, beta-endorphin and substance P neurotransmitter levels were measured from the cerebrum, cerebellum, brainstem, and midbrain.

No detectable effect on pregnancy rate was found after either maternal or paternal exposure. In the 6 000 ppm (18 500 mg/m3) group, 4 of the 78 (5%) behavioral measures, and 4 of the 64 (6%) neurochemical measures differed from those of controls. However, no dose-response correlation was observed. Thus, the NOAEC for the P and F1 generation is 18 500 mg/m3.

Most of the available studies suggest that TiO2 is biologically inert. TiO2 is insoluble in water and most ingested titanium is eliminated unabsorbed (Friberg, L. et al. 1986). Thus, TiO2 is not expected to cause any hazard on sexual function and fertility.

Short description of key information:
The weight of evidence on decomposition of tetra-n-butyl titanate, polymer with water and information from hydrolysis products indicates that this substance has no effects on fertility.

Justification for selection of Effect on fertility via oral route:
Oral route is not relevant exposure route. Inhalation is the most relevant exposure route since the target substance decomposes rapidly releasing volatile substance, n-butanol.

Justification for selection of Effect on fertility via inhalation route:
No study available for the substance itself. Based on the read-across data from the main decomposition product as the target substance is hydrolytically unstable with half-life of < 2 hours (Brekelmans, M. J. C, 2013).

Justification for selection of Effect on fertility via dermal route:
Dermal route is not considered to be relevant exposure route since skin contact in use and production of the test substance is not likely.

Effects on developmental toxicity

Description of key information

Following information is from n-butanol, the degradation product of the target substance. The most relevant exposure route of human exposure is inhalation since n-butanol is a volatile compound (vapor pressure 10 hPa at 20 degrees C). In a rat developmental toxicity study, NOAEC for maternal toxicity was 10 800 mg/m3 and NOAEC for offspring toxicity was 10 800 mg/m3.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

10 800 mg/m³

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

There is no developmental toxicity study available for the substance itself. Instead, relevant data from the degradation products is used to assess the developmental toxicity of tetra-n-butyl titanate, polymer with water. Read-across data from n-butanol and titanium dioxide (TiO2) is used for assessment, because the target substance is hydrolytically unstable having the half-life less than 2 hours (Brekelmans, M. J. C., 2013). Based on the rapid hydrolysis, the intrinsic properties are most likely related to these two decomposition products, n-butanol being the most relevant decomposition product for CSA.

There is available the developmental toxicity study for n-butanol. Groups of approximately 15 pregnant Sprague-Dawley rats were exposed via inhalation to 0, 3 500, 6 000 or 8 000 ppm (0, 10 800, 18 500, 24 700 mg/m3) of n-butanol for 7 hours/ day from gestation Day 1 - 19. On gestation day 20, the fetuses were collected and examined for both skeletal and visceral malformations.

n-Butanol concentration of 24 700 mg/m3 produced narcosis in approximately one-half of the dams. No behavioral effects were noted at 18 500 mg/m3 n-butanol. Reduction in fetal weights at 18 500 mg/m3 and 24 700 mg/m3 and a slight increase in skeletal malformations at 24 700 mg/m3 were observed in offspring. The high dose (24 700 mg/m3) was also toxic to the dams (reduced weight gain; two deaths). Feed consumption was decreased in the 18 500 mg/m3 and 24 700 mg/m3 n-butanol exposed dams. No such effect was observed following similar exposures at 10 800 mg/m3 n-butanol. The NOAEL for maternal animals was 10 800 mg/m3 and the NOAEL for offspring was 10 800 mg/m3 (based on slight decrease in fetal weight at 18 500 mg/m3).

The other decomposition product of tetra-n-butyl titanate, polymer with water is non-hazardous TiO2. Thus, it is concluded that there is no relevance to further evaluate TiO2 in the chemical safety assessment.

Justification for selection of Effect on developmental toxicity: via oral route:
Oral route is not relevant exposure route. Inhalation is the most relevant exposure route since the target substance decomposes rapidly releasing volatile substance, n-butanol.

Justification for selection of Effect on developmental toxicity: via inhalation route:
No study available for the substance itself. Based on the read-across data from the main decomposition product as the target substance is hydrolytically unstable with half-life of < 2 hours (Brekelmans, M. J. C, 2013).

Justification for selection of Effect on developmental toxicity: via dermal route:
Dermal route is not considered to be relevant exposure route since skin contact in use and production of the test substance is not likely.

Justification for classification or non-classification

The weight of evidence on decomposition of the target substance and the studies available from the hazardous degradation product, n-butanol, indicate that there is currently no need for classification of tetra-n-butyl titanate, polymer with water concerning toxicity to reproduction or teratogenicity according to the CLP Regulation (EC) 1272/2008 and EU Directive 67/548/EEC.