Aluminium triisopropanolate

Endpoint summary

Description of key information

Aluminium tri-isopropylate hydrolyses immediately to isopropanol and aluminium hydroxide / oxyhydroxide. Therefore, systemic oral toxicity and inhalation toxicity can be assessed by assessing the toxicity of aluminium 3+ cationic compounds and isopropanol.

Oral

Male Sprague-Dawley rats were exposed to aluminium hydroxide with diet at 302 mg Al/kg body weight for 28 days. During the entire experimental period, no mortality was reported and no treatment-related clinical signs were observed. There were no significant differences in body weight, food and water consumption and haematological parameters compared to controls that received basal diet. There were no other significant group differences in organ weights and microscopic changes. Aluminium concentrations in femur samples were <1 ppm (quantifiable in all 5 samples from animals treated with Al (OH)3 and in 2 samples from the control animals).The results of this study provide no evidence for significant deposition of Al in the bone and for toxicity of Al hydroxide during 28-day dietary administration at daily doses up to ≈300 mg Al/kg body weight. (Hicks 1987)

Sodium aluminium phosphate was administered to beagle dogs with diet at concentrations 0% (control), 0.3%, 1.0% and 3.0% for 6 months. There were no significant group differences in body weight throughout the experiment. Reductions in mean body weight occurred in all groups during week 27, which the authors attributed to “pre-termination tests and increased handling by technicians.” No treatment-related clinical signs and no ocular changes in any of the animals were observed. In most weeks, treated male and female dogs consumed less food than control dogs. In male animals, none of the differences in mean food consumption values were statistically significant. In females, significant reductions occurred “sporadically”. The authors did not consider these differences in food consumption as “toxicologically significant”, a conclusion that was supported by the absence of corresponding reduction in body weights. The treatment did not have any effect on haematological and blood biochemistry parameters, urinalysis results and results of analysis for occult blood in faeces. There were no significant differences in mean organ weights between the treated groups and the control group. Gross pathology and histopathology findings were in the “normal range of variations for dogs of this strain and age”; no treatment-related lesions were observed. The results of this study provide no evidence for toxicity of acidic form of sodium aluminium phosphate during 6-month administration at concentrations up to 3% in the diet (30 mg/kg bw as Al) (Katz 1984).

In a poorly documented study Aluminium (as Aluminium citrate) in drinking water was shown to affect erythropoiesis in rats with normal renal function (Vittori 1999).

The oral toxicity of isopropanol has not been investigated but can be derived form available inhalation subchronic and chronic studies, showing no systemic toxicity at the highest concentration tested. Therefore, it can be concluded that Aluminium tri-isopropylate is not expected to be of toxicological concern upon repeated dose exposure upon oral route.

  

Inhalation

Repeated exposure of rats to isopropanol for 98 days produced toxic effects only at the highest concentration (5000 ppm) and a kidney change of unknown biological significance. Clinical signs of toxicity on the central nervous system (including ataxia, narcosis, lack of a startle reflex, and/or hypoactivity) are acute effects and not relevant for limit value determination for repeated dose systemic effects. Decreases in absolute body weight and body weight gain, and changes in haematology parameters in animals exposed to 1500 and 5000 ppm of isopropanol, increased relative liver weight in male and female rats exposed to 5000 ppm, as well as increased motor activity for female rats in the 5000 ppm group have been observed (Bushi Run Research Centre 1991).

In mice clinical signs of toxicity on the central nervous system (including ataxia, narcosis, lack of a startle reflex, and/or hypoactivity) during exposures to 1500 ppm in some mice are acute effects and not relevant for limit value determination for repeated dose systemic effects. In mice exposed to 1500 and 5000 ppm of isopropanol, increased body weight and body weight gain and in female mice of the 5000 ppm group are observed. Various changes in hematologic and serum clinical chemistry parameters are observed in female mice of the 5000 ppm group, and increased relative liver weight in female mice of the 5000 ppm group (Bushi Run Research Centre 1991).

A GLP study was conducted according to OECD test guideline 451 (Burleigh-Flayer and Benson, 1994).  Isopropanol was administered by whole-body inhalation to groups of male and female Fischer 344 rats (75 rats/sex) for 6 hours/day 5 days/week for at least 104 weeks at nominal concentrations of 0 (control), 500, 2500, or 5000 ppm (measure concentrations of 0, 504, 2509, or 5031 ppm, respectively).  Ten rats/sex/group were assigned to interim sacrifice at Week 73. Isopropanol vapour produced clinical signs of toxicity (including hypoactivity, lack of startle reflex, and/or narcosis), changes in body weight, and urinalysis and urine chemistry indicative of kidney changes (decrease in osmolality and increase in total volume and/or protein) in the 2500 and 5000 ppm groups. At terminal sacrifice, increased absolute and relative kidney weights were noted in males at 2500 ppm and females at 5000 ppm. Macroscopic changes such as granular kidney were noted in males and females of 2500 and 5000 ppm groups. A number of non-neoplastic histopathological changes were observed, with the most significant being in the kidney. The only neoplastic change observed was in male rats and was an increase in interstitial cell adenomas of the testis considered to represent marked hyperplasia and not autonomous growth. The increased incidence was considered related to the unusually low frequency of testicular tumors in the control group. No increases in the incidence of neoplastic lesions were noted for female rats. In summary, the report allows the conclusion that there no adverse exposure related effects. Therefore, from the present report, a NOAEL of 5000 ppm IPA can be derived.

 

Inhalation toxicity studies on aluminium/aluminium oxide dust are of limited relevance, as aluminium tri-isopropylate upon contact with moist air would hydrolyse and hardly any aluminium dust may be formed this way but can be considered as a worst case. In an inhalation carcinogenesis study with aluminium fibres no evidence of fibrosis was seen when these fibres were administered at levels between 2 and 3 mg/m³ for 86 weeks. The respirable fraction of the particulates was 30 - 40% and the median diameter ca. 3.0μm). The only pulmonary response observed was the occurrence of pigmented alveolar macrophages. There were no lung tumors in the aluminium fibre treated animals, and no significant difference with controls in the frequency of extrapulmonary tumors was observed.

 

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1987

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

not applicable

Principles of method if other than guideline:

Male Sprague-Dawley rats were exposed to aluminium-compounds with diet. The animals were randomly assigned to five groups, 25 animals in each. The groups were receiving 1) basal diet (control), 2) aluminium hydroxide (302 mg Al/kg body weight/day), 3) KASAL -the basic form of sodium aluminium phosphate containing ≈6% of Al (141 mg Al/kg body weight/day), 4) KASAL II - the basic form of sodium aluminium phosphate containing ≈13% of Al (67 mg Al/kg body weight/day) and 5) KASAL II (288 mg Al/kg body weight/day). The treatment continued for 28 days, during which the animals were observed twice daily for their behaviour, signs of toxicity, and mortality. General physical examinations, body weight and food consumption measurements were performed weekly. After 28 days of treatment, 15 animals from each group were killed. Blood was collected from 5 rats of each group for blood cell counts, haemoglobin concentration, hematocrit and serum chemistry measurements. These rats were subjected to gross necropsy and histopathological examination. Femurs from 10 rats were taken for possible aluminium analysis; femurs from 5 rats were analyzed for Al concentrations. Five rats were allowed to recover for 2 months and five rats – for 5 months after termination of the treatment. During these recovery periods, the rats received the basal diet and were observed daily; body weight and food consumption were measured monthly. Femurs were collected at autopsy from these rats for aluminium analysis.

GLP compliance:

not specified

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

- Supplier: Charles River Breeding Laboratories, Inc.
- Number of Animals in the Study: 125
- Age at Initiation of Treatment: 48 days.
- Weight: no information
- Acclimation: 3 weeks
The animals were individually identified.

Environmental conditions
The animal room environment was maintained with the following conditions:
- Temperature: 19-24 °C;
- Relative Humidity: 40-60%;
There is no information on light/dark cycle

Dust concentration in the air of the animal room was <0.02 µg/L.

Housing & Caging
The animals were housed individually in 22.5 x 20 x 17.5 stainless steel wire-mesh cages on racks

Diet and Water
The basal diet was Purina Certified Rodent Chow no. 5002 (Ralston Purina, St Lois, MO). Aluminium concentration in the basal diet was 66 ppm. The animals had free access to water. Aluminium was detected and quantified in one of four samples of the water ( 0.017 ppm)

The contribution of Al from the room air and drinking water was estimated as <20 µg/rat during the 28 days of treatment.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The basal diet was blended with the appropriate amount of the test chemical and a small amount (0.5% wt) of Mazola corn oil “to suppress dust”.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test material concentrations “in each of the blended diets” were verified by atomic absorption spectrometry analysis. The actual concentrations were within 5% of the nominal concentrations.

Duration of treatment / exposure:

28 days

Frequency of treatment:

Daily, 7 days per week.

Dose / conc.:

14 470 ppm

Remarks:

Measured concentrations:
Al(OH)3: 302 mg Al/kg bw;
Basis:
nominal in diet

No. of animals per sex per dose:

25

Control animals:

yes, plain diet

Details on study design:

After 28 days of treatment, 15 animals from each group were killed. Blood was collected from 5 rats of each group for blood cell counts, haemoglobin concentration, hematocrit and serum chemistry measurements. These rats were subjected to gross necropsy and histopathological examination. Femurs from 10 rats were taken for possible aluminium analysis; femurs from 5 rats were analyzed for Al concentrations. Five rats were allowed to recover for 2 months and five rats – for 5 months after termination of the treatment. They were fed the basal diet during the recovery periods.

Positive control:

No data.

Observations and examinations performed and frequency:

Observations and clinical examination:
- Morbidity, signs of toxicity and mortality: twice daily
- “General physical examination”: weekly
- Food consumption: weekly for 10 animals per group
- Body weights: weekly for 10 animals per group
- Water consumption: weekly for 5 animals per group

Haematology:
Blood was collected from the abdominal aorta of 5 rats in each group at sacrifice after 28 days of treatment. Hematocrit, haemoglobin concentration, red blood cell count, white blood cell count (total and differential) and platelet count were determined.

Blood chemistry:
Blood was collected from the abdominal aorta of 5 rats in each group at sacrifice after 28 days of treatment. Alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, creatinine, phosphorus, sodium, chloride and potassium were analysed in serum.

Sacrifice and pathology:

Animals sacrificed after 28 days of treatment

Fifteen rats from each group were killed after 28 days of treatment.
Five rats were subjected to gross necropsy and histopathological examination. The brain, liver, kidneys and testes were weighted. Tissues of the heart, liver, kidney and testes were fixed in 10% neutral buffered formalin or 2.5 buffered glutaraldehyde and processed for subsequent light microscopic examination.
Femur was collected from 10 rats in each group for Al analysis; the femur of 5 rats per group was analyzed for Al concentration

Animals sacrificed after recovery periods
Five animals were killed 2 months and five animals- 5 months after termination of the treatment. Femurs were collected at autopsy for analysis of aluminium. Autopsy examination and histopathology were not performed on these animals.

Other examinations:

Bone aluminium analysis
Analyses were performed using a Perkin-Elmer 5000 (Norwalk, CT) atomic absorption spectrophotometer with a graphite furnace and Zeeman background correction system. Procedural blanks were used to correct for background Al levels and to estimate limits of detection and quantification as suggested by the American Chemical Society Committee on Environmental Improvement (1980). Values between the limit of detection and the limit of quantification could not be determined precisely and were reported as a range. Numerical values were assigned only to measurements exceeding the limit of quantification.

Measures to minimize contamination of samples by Al
Bone specimens were collected in a clean room. Personnel took shower before entering the room and wore Al-free disposable cloths. Autopsy instruments were washed with 20% nitric acid between autopsies and rinsed with distilled-deionised water. All tissues were collected in acid-washed polypropylene tubes.
Rinses of autopsy instruments and surfaces were analyzed and found to be free of Al.

Statistics:

Mean values (body and organ weights, food consumption, hematology and biochemistry parameters) from the treatment groups were compared with those from the control group using Dunnett’s Test (Dunnett, 1964. Biometrics, 22:482). Non-parametrical comparison of treated and control values was conducted using the Mann-Whitney U-test (Sokal and Rohlf, 1969). Frequencies were compared using Mantel-Haenzel trend analysis (Mantel, 1963. J. Am. Statist. Ass. 58:690) and Chi-square analysis (Sokal and Rohlf, 1969) or Fisher Exact test (Ingelfinger et al, 1983).

Clinical signs:

no effects observed

Description (incidence and severity):

Observations included abrasions, scabs, sporadic cases of chromorhinorrhoea, chromodacryorrhoea, hair loss and dehydration. All the observations were characteristic of the Sprague-Dawley rats; no unusual findings were noted.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No significant group differences throughout the treatment and recovery periods.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No significant group differences throughout the treatment and recovery periods.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

All haematological indices in the treated groups were similar to those in the control group.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

No “toxicologically significant” differences between the treated groups and the control group were observed. A mild (2-4%) but significant increase in serum sodium level was observed in all treated group compared to the control group. However, all the increased sodium levels were within the range of historical control for rats of the same age in the laboratory.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

A significant 16% increase in absolute kidney weight was observed in the group of rats receiving KASAL II at the dose of 67 mg Al/kg b.w. This increase appeared to be not treatment-related because no such increase was seen in the group of animals treated with KASAL II at the dose of 288 mg Al/kg b.w. There were no other significant group differences in organ weights.

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

All lesions seen at microscopic examination were “those normally expected for young adult male Sprague-Dawley rats.” No lesions suggestive of a treatment-related effect were seen.

Histopathological findings: neoplastic:

no effects observed

Details on results:

Mortality:
No mortality was reported.

Body weight:
No significant group differences throughout the treatment and recovery periods.

Clinical Observations:
Observations included abrasions, scabs, sporadic cases of chromorhinorrhoea, chromodacryorrhoea, hair loss and dehydration. All the observations were characteristic of the Sprague-Dawley rats; no unusual findings were noted.

Food and Water Consumption:
No significant group differences throughout the treatment and recovery periods.

Haematology:
All haematological indices in the treated groups were similar to those in the control group.

Clinical Chemistry:
No “toxicologically significant” differences between the treated groups and the control group were observed. A mild (2-4%) but significant increase in serum sodium level was observed in all treated group compared to the control group. However, all the increased sodium levels were within the range of historical control for rats of the same age in the laboratory.

Organ Weight:
A significant 16% increase in absolute kidney weight was observed in the group of rats receiving KASAL II at the dose of 67 mg Al/kg b.w. This increase appeared to be not treatment-related because no such increase was seen in the group of animals treated with KASAL II at the dose of 288 mg Al/kg b.w. There were no other significant group differences in organ weights.

Histology:
All lesions seen at microscopic examination were “those normally expected for young adult male Sprague-Dawley rats.” No lesions suggestive of a treatment-related effect were seen.

Dose descriptor:

NOAEL

Effect level:

302 mg/kg diet

Based on:

test mat.

Sex:

male

Basis for effect level:

other: absence of effects

Critical effects observed:

not specified

Tissue Metal Levels:

Aluminium levels in the femur

All the concentrations were <1 ppm and most were below the limit of detection or quantification. The distribution of samples in which Al was not detectable, was detectable but not quantifiable or was quantifiable was similar in all the groups (the comparison using Chi-square analysis). It should be noted that this comparison was based on small numbers of samples from each group (5). Al was quantifiable in all 5 samples from animals treated with Al (OH)₃ and in 2 samples from the control animals.

Conclusions:

The results of this study provide no evidence for significant deposition of Al in the bone and for toxicity of Al hydroxide during 28-day dietary administration at daily doses up to ≈300 mg Al/kg body weight.

Executive summary:

Male Sprague-Dawley rats were exposed to aluminium-compounds with diet. The animals were randomly assigned to five groups, 25 animals in each. The groups were receiving 1) basal diet (control), 2) aluminium hydroxide (302 mg Al/kg body weight), 3) KASAL -the basic form of sodium aluminium phosphate containing ≈6% of Al (141 mg Al/kg body weight), 4) KASAL II - the basic form of sodium aluminium phosphate containing ≈13% of Al (67 mg Al/kg body weight) and 5) KASAL II (288 mg Al/kg body weight). The treatment continued for 28 days, during which the animals were observed twice daily for their behaviour, signs of toxicity, and mortality. General physical examinations, body weight and food consumption measurements were performed weekly. After 28 days of treatment, 15 animals from each group were killed. Blood was collected from 5 rats of each group for blood cell counts, haemoglobin concentration, hematocrit and serum chemistry measurements. These rats were subjected to gross necropsy and histopathological examination. Femurs from 10 rats were taken for possible aluminium analysis; femurs from 5 rats were analyzed for Al concentrations. Five rats were allowed to recover for 2 months and five rats – for 5 months after termination of the treatment. During these recovery periods, the rats received the basal diet and were observed daily; body weight and food consumption were measured monthly. Femurs were collected at autopsy from these rats for aluminium analysis. During the entire experimental period, no mortality was reported and no treatment-related clinical signs were observed. All clinical observations were characteristic of male Sprague-Dawley rats of relevant age. There were no significant group differences in body weight, food and water consumption and haematological parameters. A mild (2-4%) but significant increase in serum sodium level was observed in all treated group compared to the control group. However, all the increased sodium levels were within the range of historical control for rats of the same age in the laboratory. A significant 16% increase in absolute kidney weight was reported in the group of rats receiving KASAL II at 67 mg Al/kg b.w. This increase appeared to be not treatment-related because no such increase was seen in the group of animals treated with this substance at 288 mg Al/kg b.w. There were no other significant group differences in organ weights. All lesions seen at microscopic examination were “those normally expected for young adult male Sprague-Dawley rats.” No lesions suggestive of a treatment-related effect were seen. Aluminiumconcentrations in all femur samples from all groups were <1 ppm and most were below the limit of detection or quantification. The distribution of samples in which Al was not detectable, was detectable but not quantifiable or was quantifiable, was similar in all the groups. It should be noted that this comparison was based on small numbers of samples from each group (5). Al was quantifiable in all 5 samples from animals treated with Al (OH)₃, in 2 samples from the control animals and in none of the samples from animals treated with KASAL or KASAL II.The results of this study provide no evidence for significant deposition of Al in the bone and for toxicity of Al hydroxide or basic food grade sodium aluminium phosphate (KASAL and KASAL II) during 28-day dietary administration at daily doses up to ≈300 mg Al/kg body weight. 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

For the other hydrolysis product isoproanol no repeated dose study via the oral route was available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: inhalation

Remarks:

combined repeated dose and carcinogenicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented, according to accepted guidelines

Qualifier:

according to guideline

Guideline:

other: OECD 451

Deviations:

yes

Remarks:

Not monitoring food consumption

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley Inc. Indianapolis, IN
- Age at study initiation: 28-30 days old
- Weight at study initiation: 121.2-165 g (males) and 93.6 - 124.3 g (females) on the first day of exposure
- Fasting period before study: None
- Housing: 2 per cage in stainless steel, wire mesh cages
- Diet (e.g. ad libitum): Pelleted, certified AGWAY PROLAB animal diet rat 3000 ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature : 17 - 26 °C
- Humidity (%): 40-70
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12-12

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: Not reported

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation chamber (Wahmann Manufacting company, Timonium, MD)
- System of generating particulates/aerosols: liquid isopropanol was metered from a container by piston pump
- Temperature in air chamber: 22 +/- 4 degrees
- Air flow rate: 1000 l/min for first month and 900 l/min thereafter
- Air change rate: 14 air changes/hr for first month and 12.5 air changes/hr thereafter
- Method of particle size determination: not reported
- Treatment of exhaust air: not reported


TEST ATMOSPHERE
- Brief description of analytical method used: liquid isopropanol was metered from a container by piston pump into a heated glass evaporator and the temperature of the evaporators was maintained at the lowest level to sufficiently vaporize the test substance.
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Each exposure chamber was analyzed for isopropanol twice each hour by flame ionization gas chromatography.

Duration of treatment / exposure:

at least 104 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Remarks:

Doses / Concentrations:
0, 500, 2500, 5000 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

65 sex/dose for the core group and 10 sex/dose for the interm sacrifice

Control animals:

yes, sham-exposed

Details on study design:

- Rationale for animal assignment (if not random): animals were assigned to 3 exposure groups and a control group using a sacrificed randomization procedure based on body weight
- Rationale for selecting satellite groups: 10 sex/group were sacrified in the middle of the study

Positive control:

None

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 for the first 14 weeks and then every other week after

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No data

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: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: prior to experiment, and during weeks 71, 80, 104, and 107
- Dose groups that were examined: all rats


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 13 months, 19 months, and 25 months
- Anaesthetic used for blood collection: Yes (identity) methoxyflurane
- Animals fasted: No
- How many animals: 10 sex/dose level

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: week 57
- Animals fasted: No
- How many animals: 10 sex/dose group

URINALYSIS: Yes
- Time schedule for collection of urine: week 57, 59, 74, and 104
- Metabolism cages used for collection of urine: No
- Animals fasted: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Other examinations:

None

Statistics:

The data for the 3 treatment groups and the control group were compared with Levene's test for equality of variances, analysis of variance (ANOVA), and t-tests. The nonparmetric data were statistically evaluated with the Kruskal-Wallis test followed by the Mann-Whitney U-test. Mortality was analysed by life-table analyses. Incidence data were compared using Fishers exact test.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY
- Mortality rates for males in the 0, 500, 2500, and 5000 ppm groups were 82, 83, 91, and 100%, respectively. For females, 54, 48, 55, and 69%. No significant differences were noted for male rats from 500 or 2500 groups or any female rats.
-In males and females exposed to 5000 ppm; hypoactivity, lack of a startle reflex, and narcosis were identified. In males and females exposed to 2500 ppm; hypoactivity, and a lack of a startle reflex were observed. No effects in 500 ppm group. During non-exposure periods in males 5000 ppm group emaciation and dehydration was observed. In males and females in 5000 ppm there was greater numbers of rats with urine stains and swollen periocular tissue (females only). Females in the 2500 ppm group also had increased incidence of urine stains.

BODY WEIGHT AND WEIGHT GAIN
-Decreased body weights were observed for male rats from the 5000 ppm group in the first and second weeks of exposure, and then increased and at the end of week 6 body weights were increased significantly over the control group. Increased body weights were also noted for male rats from the 2500 ppm group.
-Decreased body weights were observed for female rats from the 5000 ppm group in the first and second weeks of exposure, and then increased and at the end of week 5 body weights were increased significantly over the control group. Increased body weights were also noted for female rats from the 500 ppm group. At week 72, all female body weights were significantly increased when compared to the control group.

URINALYSIS
-In males in the 5000 ppm group, in weeks 57, 59, 74, and 104 decrease in osmolality and increase in total protein and total volume were reported.
-In females rats in the 5000 ppm group, a decrease in osmolality and an increase in total volume was reported. At week 74, total glucose excreted in the urine was increased for females in the 5000 ppm group.


ORGAN WEIGHTS
- At the interim sacrifice, absolute and relative kidney weights were increased for male rats in the 5000 ppm group. Relative liver weights were increased for male rats in the 2500 ppm group. Concentration-related increases in absolute and relative testes weight was reported for male rats in 5000 ppm group. In females, increases in absolute and relative lung weight for rats in the 5000 ppm was reported.
-At the terminal sacrifice, increase in relative liver weight was noted for male rats in 2500 ppm group. In females, an increase in absolute and relative liver and kidney weights were noted for the 5000 ppm group.


GROSS PATHOLOGY
- At the interim sacrifice, an increase in granular kidneys in male rats from the 2500 and 5000 ppm groups were noted
- At the terminal sacrifice, an increase in granular kidneys in male rats from the 2500 ppm group was noted. Increased frequencies of gross lesions for male rats that died included increase incidence of thickened stomachs, granular kidneys, and color change of the kidneys for animals in 2500 and 5000 ppm groups.
- For females that died before the end of the study, an increased incidence of thickened stomachs was noted for animals from the 5000 ppm group and granular kidneys were noted for animals from the 2500 and 5000 ppm groups.


HISTOPATHOLOGY: NON-NEOPLASTIC
- At the interim sacrifice, male rats from the 5000 ppm group had an increased frequency of testicular seminiferous tubule atrophy.
-Increased frequencies of kidney lesions were observed in male rats in the 2500 and 5000 dose groups that died during the study. Increased in the frequency of mineralization in the heart, aorta, vasculature, stomach, larynx, trachea, lungs, kidney, cornea, and testes was noted for male rats in the 2500 and 5000 ppm dose groups that died during the study. Additionally, basophilic cell foci in the liver, splenic hemosiderosis, rhinitis, and squamous metaplasisa of the respiratory epithelium in the nasal cavity were reported for male rats in the 5000 ppm group that died during the study.
-Increased severity of glomerulosclerosis was observered in female rats in the 5000 ppm group. Renal disease was also increased in female rats in the 5000 ppm group.
- For female rats that died during the study, increased frequencies of mineralization in the heart, aorta, vasculature, stomach, larynx, trachea, lungs and kidney. Increase in myocardial degeneration, atrial thrombosis, splenic hemosiderosis, ocular keratitis, inflammatory and metaplastic changes in the nasal cavity, squamous metaplasia of the respiratory epithelium and glandular ectasia in the gastric mucosa was also evident in females in the 5000 ppm group that died during the study.


HISTOPATHOLOGY: NEOPLASTIC (if applicable)
-Dose-related increase in interstitial cell adenomas of the testis in male rats at interim sacrifice, at the terminal sacrifice, and in male rats that died during the study.

Dose descriptor:

NOEC

Effect level:

500 ppm

Sex:

male/female

Basis for effect level:

other: for species specific toxic effects

Dose descriptor:

NOAEC

Effect level:

5 000 ppm

Basis for effect level:

other: The report allows the conclusion that there are no substance specific adverse exposure related effects. A NOAEL of 5000 ppm can be derived.

Dose descriptor:

NOEC

Effect level:

5 000 ppm

Sex:

male/female

Basis for effect level:

other: for oncogenicity effects

Critical effects observed:

not specified

Executive summary:

The inhalation toxicity of IPA has been assessed in a 104-week oncogenicity study in rats (Burleigh-Flayer and Benson, 1994). This GLP study was conducted according to OECD test guideline 451.  IPA was administered by whole-body inhalation to groups of male and female Fischer 344 rats (75 rats/sex) for6 hours/day 5 days/weekfor at least 104 weeks at nominal concentrations of 0 (control), 500, 2500, or 5000 ppm (measure concentrations of0, 504, 2509, or 5031 ppm, respectively).  Ten rats/sex/group were assigned to interim sacrifice at Week 73. Animals were monitored for clinical observations, body and organ weights, ophthalmology examinations, hematology, urinalysis and urine chemistry examinations, gross pathology and microscopic examinations.

Exposure of rats to IPA vapour for 104 weeks produced clinical signs of toxicity (including hypoactivity, lack of startle reflex, and/or narcosis), changes in body weight, and urinalysis and urine chemistry indicative of kidney changes (decrease in osmolality and increase in total volume and/or protein) in the 2500 and 5000 ppm groups. At terminal sacrifice, increased absolute and relative kidney weights were noted in males at 2500 ppm and females at 5000 ppm. Macroscopic changes such as granular kidney were noted in males and females of 2500 and 5000 ppm groups. A number of non-neoplastic histopathological changes were observed, with the most significant being in the kidney. The only neoplastic change observed was in male rats and was an increase in interstitial cell adenomas of the testis considered to represent marked hyperplasia and not autonomous growth. The increased incidence was considered related to the unusually low frequency of testicular tumors in the control group. No increases in the incidence of neoplastic lesions were noted for female rats. In summary, the report allows the conclusion that there no adverse exposure related effects. Therefore, from the present report, a NOAEL of 5000 ppm IPA can be derived.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

12 270 mg/m³

Study duration:

chronic

Species:

rat

Quality of whole database:

Based on exposure during 6 hours/day 5 days/week. As isopropanol is the most volatile hydrolysis product, data on aluminium will not be taken into account for toxicity via inhalation.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Mode of Action Analysis / Human Relevance Framework

Although inhalation exposure may not be too relevant for aluminium tri-isopropylate, hydrolysis forms isopropanol having a rather high vapour pressure and exposure to isopropanol, when handling aluminium tri-isopropylate, is considered relevant. Isopropanol has been investigated in a subchronic inhalation study as well in a chronic carcinogenicity study, both using rats as test animals and both resulting in a NOAEC of 5000 ppm (highest tested dose in both studies). Hence, it can be concluded, that no systemic or local effects from isopropanol inhalation exposure is to be expected. In conclusion of a weight of evidence approach it can be summarized, that neither aluminium hydroxide nor isopropanol caused significant effect in subacute, subchronic and chronic studies, neither by oral nor inhalation exposure. The results are sufficient for deciding upon repeated exposure classification and systemic toxicity of aluminium tri-isopropylate can be considered not being relevant. Also no significant local effects were noted in the inhalation studies.

Additional information

For risk assessment purposes the lowest derived occupational exposure limit for isopropanol (500 mg/m3) will be used as starting point for inhalation exposure, as absorption of isopropanol is expected to be significantly higher than that of aluminium hydroxide. For dermal toxicity a NOAEL based on route-to-route extrapolation from the occupational exposure limit on isopropanol will be used as starting point, also based on the relatively large difference in absorption to be expected between isopropanol and aluminium (III) compounds.

Justification for classification or non-classification

Based on a weight of evidence approach building on subacute, subchronic and chronic studies performed with Isopropanol and different Al3+ compounds it can be concluded that aluminium tri-isopropylate does not require classification for Systemic Target Organ Toxicity, Repeat Exposure (STOT RE) according to CLP (Regulation EC No 1282/2008)