Aluminium tri-sec-butanolate

Endpoint summary

Description of key information

Upon contact with water or moisture (e.g. within mucous membranes) aluminium tri-sec-butanolate hydrolyses immediately to butan-2-ol and aluminium 3+ cations (as hydroxide and oxyhydroxide). Hence, toxicity is determined by the toxicity of these two species

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).

Although inhalation exposure may not be too relevant for aluminium tri-sec-butylate, hydrolysis forms 2-butanol having a high vapour pressure and exposure to 2-butanol, when handling aluminium tri-sec-butylate, is considered relevant. 2-butanol itself has not been investigated in a subchronic inhalation study but its primary metabolite methyl ethyl ketone using rats as test animals and resulting in a NOAEC of 2518 ppm, 7425 mg/m3 (mid dose tested). Main effects at the high dose in this study were reduced body weight and reduced organ weight with liver and kidneys being target organs. Hence, it can be concluded, that only limited systemic or local effects at elevated concentrations from 2-butanol inhalation exposure is to be expected.
Inhalation toxicity studies on aluminium/aluminium oxide dust are of limited relevance, as aluminium tri-sec-butylate 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 sub-chronic studies performed with rats (6 month) guinea pigs (12 month) and hamsters (6 month) by Gross et al. (1973) NOAEC values of 70 mg/m3, 30 mg/m3 and 70 mg/m3 air respectively were found.

In conclusion of a weight of evidence approach it can be summarized, that neither aluminium³⁺ nor 2-butanol caused significant effect in subacute and subchronic studies.

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:

adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

subacute study in rats with Al(OH)3
No data on oral toxicity for the other hydrolysis product butan-2-ol

System:

other: no treatment related effects

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well documented, according to accepted guidelines, for read-across substance.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Deviations:

no

GLP compliance:

yes

Remarks:

However, GLP statement was not signed

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, MI
- Age at study initiation: 6 weeks old
- Weight at study initiation: 117-119 g (males) and 93-94 g (females)
- Housing: Individual housing in 8 cubic meter stainless steel and glass chambers
- Diet (e.g. ad libitum): Purina Certified Rodent Chow ad libitum, except during exposure
- Water (e.g. ad libitum): Filtered tap water ad libitum, except during exposure
- Acclimation period: 14-day quarantine period


ENVIRONMENTAL CONDITIONS
- Temperature (°F): approximately 70 ºF
- Humidity (%): approximately 50%
- Photoperiod (hrs dark / hrs light): 12 hours:12 hours

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

The test article was vaporized in a 3-neck, round bottom flask. The test article was metered to the vaporization flask using a FMI Lab Pump. The vapors were swept from the flask by a continuous supply of conditioned, compressed air and entered the chamber through a turret located at the top of the chamber. In the turret, the vapors were mixed with chamber supply air. The metered flow of test article into the vaporization flask and total air through the chamber were adjusted to maintain the target concentration within the chamber. The test article delivery rate and total airflow through the chamber were used in calculating the nominal concentration within the chamber.

Airflow was monitored continuously throughout the exposure by reading the pressure differential from a minihelic pressure gauge and recording the corresponding airflow from a prepared calibration graph showing airflow versus differential pressure. The graph was prepared by plotting various airflow readings from an Autotronic Controls Turbine Flow Meter at different differential pressure readings and drawing a-curve. The negative pressure of each test chamber was maintained at 0.1 inches of water. The control chamber was maintained at a positive pressure of 0.02 inches of water. Negative and positive pressures were measured with minihelic pressure gauges.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

A gas chromatographic chamber monitoring system was employed throughout the study to analyze chamber air samples obtained by both manual and automatic sampling methods. Precision sampling gas syringes were used to obtain the manual samples of the test atmosphere by piercing a self-sealing rubber septum inserted in the two sampling ports on the chamber doors. Samples obtained were injected into the gas chromatograph to determine chamber concentration. Automated chamber monitoring was achieved using a Valco Instruments custom designed, pneumatically operated sampling system. The system operated using a continuous flow through a 16-port multiple stream complex in conjunction with a 10-port gas sampling valve. The 10-port valve was plumbed into the gas chromatograph via the carrier inlet and analytical column. A calibrated sample loop was used to control the injection volume. A digital valve controller determined the frequency of injections and started the analog to digital converter which transferred the gas chromatographic results to the data system. The data system read the position of the sampling valve for sample identification and computed the concentration based on peak areas. Results of all injections were stored in data files and the time-weighted average (TWA) computed for each exposure day. The chamber air monitoring instruments were located in a space physically separated from the inhalation laboratory.

Each test chamber was sampled approximately once/hour. Control chamber and room atmospheres were sampled from one to five times/day. All samples were monitored for hexane and methyl ethyl ketone. A Miran IA infrared analyzer was used as a continuous monitor in all test chamber on a selected basis for distribution studies. A stainless steel bellows pump pulled chamber air through the gas cell and exhausted it back into the chamber. A chart recorder was used to obtain a continuous readout of absorbance. The concentration was determined using a calibration graph.

Duration of treatment / exposure:

89 or 90 consecutive days.

Frequency of treatment:

6 hours/day, 5 days/week (use of non-standard dosing regime was used to simulate the conditions encountered in the workplace).

Remarks:

Doses / Concentrations:
1254 ppm
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
2518 ppm
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
5041 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

15 rats/sex/dose

Control animals:

yes, concurrent no treatment

Positive control:

None used.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice-daily.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Twice-daily.

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

OPHTHALMOSCOPIC EXAMINATION: Yes

HAEMATOLOGY: Yes

CLINICAL CHEMISTRY: Yes

URINALYSIS: Yes
- Time schedule for collection of urine: prior to necropsy
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes

OTHER: Five males and five females (Dedicated animals) from each exposure group and the control group were used exclusively for the following special study. The thoracic aorta was cannulated via the left ventricle. Vascular perfusion with lactated Ringer’s solution was immediately followed with 2% glutaraldehyde. Following perfusion, the brain, spinal cord, and right and left sciatic and tibial nerves were removed and placed in glutaraldehyde overnight. The next day they were washed in phosphate buffer. Sections of medulla and the tibial nerve were osmicated and dehydrated. The medulla and sciatic nerve were embedded in Epon, sectioned at 1 micrometer and stained with toluidine blue. The tibial nerve was osmicated, placed in an Epon mixture and then teased on a glass slide to isolate individual nerve fibers. A minimum of fifty nerve fibers/animal were evaluated by light microscopy for evidence of neuropathy. Other tissues were stored in 10% neutral buffered formalin. Specimens from all groups were examined.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

Parametric data such as body weight or food consumption were analyzed using an analysis of variance (ANOVA). Statistically significant differences that were noted were further studied by either Tukey’s (equal populations) or Scheffe’s (unequal populations) Test of Multiple Comparison. Non-Parametric data such as organ weight ratios were analyzed using a Kruskal-Wallis ANOVA and a Test of Multiple Comparison.

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):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

effects observed, treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY: None of the animals died; however, clinical signs observed included irritation, swelling, or crustiness associated with the animal’s ear tag. Crusty eye was observed in both control (6) and test (4) animals. Crusty muzzle was observed in one test animal as was crusty nose in another. None of the observations noted were considered to be related to test article administration.

BODY WEIGHT AND WEIGHT GAIN: Significant difference between control and test group mean body weight gains was observed in male and female rats of the high-dose group. The high-dose male and female body weights were transiently depressed early in the study, starting at week one, while the low-dose male and mid-dose male and female body weights were elevated as the study progressed.

OPHTHALMOSCOPIC EXAMINATION: None of the abnormalities observed were considered significant since they were distributed in both control and test animals and because these abnormalities are common in Fischer 344 rats of this age.

HAEMATOLOGY: The mean corpuscular hemoglobin in high-dose male and female rats was significantly higher than that of controls. In high-dose female rats, the mean corpuscular hemoglobin concentration was also elevated. This increase in hemoglobin corresponds to a slight but not significant decrease in the number red blood cells. No additional significant differences between test and control animals were observed.

CLINICAL CHEMISTRY: No significant differences between test and control animals were observed in male rats. Glutamic pyruvic transaminase was elevated in mid-dose females. Alkaline phosphatase and glucose were significantly increased in high-dose female rats. The trend, although not statistically significant, was also seen in male rats. The increase in alkaline phosphatase is probably associated with the significant increase in liver weight. The elevation is considered mild. It should be noted that the sodium and potassium values are high for all groups. This was possibly due to a delay (10 days) in running these chemistries because of instrumentation down-time. It is most probable that evaporation occurred in all samples resulting in the high values in all samples. Potassium levels in high-dose females were statistically higher than control values.

URINALYSIS: No statistical differences between test and control animals were observed except for the volume of the urine in male rats which was elevated; however, all values were within the normal range for rats, and the differences were not considered to be related to test article administration.

ORGAN WEIGHTS: In high-dose male rats, the liver weight, liver/body weight ratio, and liver/brain weight ratio were significantly elevated. The kidney/body weight ratio was significantly elevated in the same animals. In female rats a significant dose response was observed in increased liver weight. In high-dose female rats, significantly depressed spleen and brain weights were also observed. The liver/body weight ratio was significantly elevated and the brain/body weight ratio was significantly depressed in high-dose female rats. Also in high-dose female rats, the liver/brain and kidney/brain weight ratios were significantly elevated.

GROSS PATHOLOGY: Most lesions were minor in nature and limited in their frequency of occurrence. None were interpreted as related to the administration of the test article. Only one tissue mass (neoplasm) was observed, and it occurred in a control male. The mesenteric tissue masses seen in 3 animals proved to be accessory spleens. A reddish discoloration of the mandibular lymph nodes was observed in 22 rats and was noted at least in one rat from all four groups. Likewise, 10 to 20 percent of the animals in all four groups exhibited insignificant exudation around the site of the ear tags. A relatively high percentage (20 to 40 percent) of the females (other than in high-dose animals) had cysts of the ovaries. These cysts were one centimeter or less in diameter, thin-walled, and contained clear to reddish fluid. Other lesions were minor and occurred randomly in all groups.

HISTOPATHOLOGY: NEOPLASTIC (if applicable): Histopathologic lesions attributable to the test article administration were not present in any of the rats. A wide variety of histopathologic lesions were observed; however, they were considered to be spontaneous in origin, occurring randomly in a small percentage of the animals from all four groups.

Dose descriptor:

NOAEC

Effect level:

2 518 ppm

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Critical effects observed:

not specified

No changes in neurological function was observed.

Conclusions:

NOAEC (rat, 90d, inhal.): 2518 ppm

Executive summary:

No NOAEC value was reported by the study author. Review of the study data suggests that a NOAEC of 2,518 ppm can be considered for subchronic inhalation exposure, based on effects noted in both sexes at 5,041 ppm including decreased body weight and increased absolute and relative liver weights and liver to brain weight ratios.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

7 425 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

Data on the metabolite of butan-2-ol methyl ethyl ketone (metabolic conversion from 2-butanol to MEK was shown to be 97%, see toxicokinetic section)

Based on exposure during 6 hours/day 5 days/week. As butan-2-ol is the most volatile hydrolysis product. Data on aluminium oxide will not be taken into account for toxicity via inhalation.

System:

other: body weight, effects on liver and kidney weight

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

Upon contact with water or moisture (e.g. within mucous membranes) aluminium tri-sec-butanolate hydrolyses immediately to butan-2-ol and aluminium 3+ cations (as hydroxide and oxyhydroxide). Hence, toxicity is determined by the toxicity of these two species. Further details on the appraoch are provided in the attachment to section 13.

Additional information

Taking into consideration that the absorption of butan-2-ol is expected to be >100 times higher than that of aluminium hydroxide, the following starting points for risk assessment were defined.

The 90-day study with methyl ethyl ketone, the primary metabolite of buran-2-ol, will be considered as starting point for inhalation exposure. In a worst case approach the DNEL will be calculated using the inhalation developmental toxicity study (Nelson 1989) as depicted in section 7.8.2.

For dermal toxicity the NOAEL from the oral the oral two-generation study (EPA 2003) will be used as starting point, also based on the large difference in dermal absorption to be expected between butan-2-ol and aluminium (III) compounds.

Justification for classification or non-classification

Based on a weight of evidence approach building on subacute and subchronic studies performed with butan-1-ol and different Al3+ compounds it can be concluded that aluminium tributanolate does not require classification for Systemic Target Organ Toxicity, Repeat Exposure (STOT RE) according to CLP (Regulation EC No 1282/2008).