Aluminium oxide

Endpoint summary

Description of key information

Oral: LD50 (rat) > 2000 mg/kg bw
Inhalation: LC50(rat) > 2.3 mg/L

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

: lack of details on test substance, no data available about the control group, no details available on the preparation of dosing solution and physical form of the administered compound.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (no further information)
- Age at study initiation: No data available.
- Weight at study initiation: 183-299 grams (males) and 158-204 grams (females).
- Fasting period before study: Animals were fasted overnight prior to treatment.

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

No details available.

Doses:

1000, 1590, 2510, 3980, 6310, 10000, and 15900 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

not specified

Details on study design:

Duration of observation period following administration: 14 days.
Frequency of observation in all animals: immediately after dosing, 1, 4 and 24 hours after dosing, and one daily during the total of 14 days observation period.
At the end of study, gross necroscopy was performed on all animals (animals which died during the study and on those sacrificed by chloroform overdose).

Statistics:

No data available.

Preliminary study:

Not performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 15 900 mg/kg bw

Based on:

test mat.

Mortality:

The fumed alumina did not cause mortality in males and females Sprague-Dawley rats after an acute oral exposure (gavage) to 1000, 1590, 2510, 3980, 6310, 10000 and 15900 mg/kg bw.

Clinical signs:

other: No toxic effects were noted in aluminium treated animals at doses from 1000 mg/kg to 10000 mg/kg. At dose 15900 mg/kg, clinical signs of depression, laboured respiration, and piloerection (males) were noted immediately after administration of the compou

Gross pathology:

No changes in gross pathology were noted at sacrifice.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for acute oral toxicity, no classification is required.

Executive summary:

An acute oral toxicity study comparable to OECD 401 was performed with fumed alumina in female and male rats. This study has been performed at the Hazelton Laboratories, Inc.. Fumed alumina was administered by a single oral gavage to seven groups of five males and five females per group at dose levels of 1000, 1590, 2510, 3980, 6310, 10000 and 15900 mg/kg bw after an overnight food withdrawal.

Parameters monitored during this study included mortality and clinical signs of possible intoxication.Clinical observations were performed on all animals immediately after dosing, at 1, 4 and 24 hours after dosing and daily for 14 days thereafter.

During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose range from 1000 mg/kg to 10000 mg/kg bw. 

Clinical signs of depression, laboured respiration, and piloerection (males) were noted immediately and hunched appearance was noted at 24 hours post-administration of the highest dose 15900 mg/kg. 

No significant sex differences were noted among animals in the sensitivity to the administered compound or during the recovery period. Animals appeared normal by day 7 (females) and day 8 (males).

Macroscopic examination at the end of the observation period did not reveal any aluminium-related changes of the internal organs of the aluminium treated animals compared to the control group.

Under the conditions of this study, the acute oral median lethal dose (LD50) of the fumed alumina is above 15900 mg/kg bw in both females and males rats.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

: lack of details on test substance; No details available on the preparation of dosing solution and physical form of the administered Al hydroxide

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Institute colony
- Age at study initiation: no data
- Weight at study initiation: 135 to 188 grams (males) and 93-116 grams (females).
- Fasting period before study: animals were fasted overnight prior to treatment.
- Housing: the rats were housed in groups of 5 in screen-bottom stainless-steel cages.
- Diet: animals were fed with stock diet, ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±1 °C
- Air changes (per hr): Well ventilated room (no other data available)

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Al oxide was prepared as 33% (w/v) aqueous suspension and administered by a single oral dose.
Treatment volume applied: 3 mL/100 g body weight.
Administered dose was equivalent to 10000 mg test substance per kg body weight.

Doses:

10000 mg/kg bw

No. of animals per sex per dose:

10

Control animals:

not specified

Details on study design:

Before dosing the rats were fasted overnight.
After treatment animals received stock diet and water ad libitum.
Duration of observation period for possible signs of intoxication: 14 days.
At the end of study (after 14 days of observations), autopsy was performed on all animals.

Statistics:

No data available.

Preliminary study:

Not performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 10 000 mg/kg bw

Based on:

test mat.

Mortality:

Aluminium oxide did not cause mortality in males and females (Wistar) rats after an acute oral exposure (gavage) to 10000 mg/kg bw.

Clinical signs:

other: No death occurred after the treatment. At dose 10000 mg/kg, no clinical signs of intoxication were observed during the post-administration observation period. Animals appeared healthy through the observation period.

Gross pathology:

Macroscopic examination of the exposed animals did not reveal any treatment–related gross alterations.

Other findings:

None.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for acute oral toxicity, no classification is required.

Executive summary:

An acute oral toxicity study was performed with aluminium oxide (granulated solid product, TBH) in both female and male rats.

This study has been performed at the Central Institute for Nutrition and Food Research, Germany.

Al₂O₃was administered by a single oral gavage to ten males and ten females per group at dose level of 10000 mg/kg bw after an overnight food withdrawal.

Parameters monitored during this study included mortality, clinical signs of possible intoxication, and changes in gross pathology.Clinical observations were performed on all animals during 14 days there the Al₂O₃administration.

During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose 10000 mg/kg bw. 

No significant sex differences were noted among animals in the sensitivity to the administered compound. 

Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

: lack of details on test substance

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Institute colony.
- Age at study initiation: no data
- Weight at study initiation: 285-360 grams (males) and 165-212 grams (females).
- Fasting period before study: yes, overnight prior to treatment.
- Housing: The rats were housed in groups of 5 in screen-bottom stainless-steel cages.
- Diet: Animals were fed with stock diet, ad libitum.
- Water: ad libitum
- Acclimation period: Not required.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±1 °C
- Air changes (per hr): Well ventilated room (no other data available)

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Al oxide was prepared as 33% (w/v) aqueous suspension and administered as single oral dose.
Treatment volume applied: 3 mL/100 g body weight.
Administered dose was equivalent to 10000 mg test substance per kg body weight by gavage as a highest tolerable dose in one single oral dose.

Doses:

10000 mg/kg bw

No. of animals per sex per dose:

10

Control animals:

not specified

Details on study design:

Before dosing the rats were fasted overnight.
After treatment animals received stock diet and water ad libitum.
Duration of observation period for possible signs of intoxication: 14 days.
At the end of study (after 14 days of observations), gross necroscopy was performed on all animals.

Statistics:

No data available.

Preliminary study:

Not performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 10 000 mg/kg bw

Based on:

test mat.

Mortality:

Aluminium oxide did not cause mortality in males and females (Wistar) rats after an acute oral exposure (gavage) to 10000 mg/kg bw.

Clinical signs:

other: No death occurred after the treatment. At dose 10000 mg/kg, no clinical signs of intoxication were observed during the post-administration observation period. Animals appeared healthy through the observation period.

Gross pathology:

Macroscopic examination of the exposed animals did not reveal any treatment–related gross alterations.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for acute oral toxicity, no classification is required.

Executive summary:

An acute oral toxicity study comparable to OECD 401 with acceptable restrictions was performed with aluminium oxide (granulated solid product, TOF) in both female and male rats.

This study has been performed at the Central Institute for Nutrition and Food Research,.

Al₂O₃was administered by a single oral gavage to ten males and ten females per group at dose level of 10000 mg/kg bw after an overnight food withdrawal.

Parameters monitored during this study included mortality, clinical signs of possible intoxication, and changes in gross pathology. Clinical observations were performed on all animals during 14 days there the Al₂O₃administration.

During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose 10000 mg/kg bw. 

No significant sex differences were noted among animals in the sensitivity to the administered compound. 

 

Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

Reference 4

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

: lack of details on test substance

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Institute colony.
- Age at study initiation: no data available.
- Weight at study initiation: 116 - 328 grams (males) and 78-160 grams (females).
- Fasting period before study: animals were not fasted before the study.
- Housing: The rats were housed in groups of 5 in screen-bottom stainless-steel cages. At the end of the pre-treatment diet period, the rats were hosed individually.
- Diet: animals were fed with diet, ad libitum.
- Water: ad libitum
- Acclimation period: No data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±1 °C
- Air changes (per hr): Well ventilated room (no other data available)

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

Al oxid C was mixed with stock diet at a ratio of 1:4 in an amount of 10000 mg /kg body weight ratio of 1:4 (not clear).
Administered dose was equivalent to 10000 mg test substance per kg body weight (bw).

Doses:

10000 mg/kg bw

No. of animals per sex per dose:

10

Control animals:

not specified

Details on study design:

Before administration of the Aluminium oxid C, animals were trained to eat the normal daily amount of food by providing food only during 4 hours on each day during 1 week. At this time, the stock diet was mixed with cellulose powder (ratio 4:1, w/w). At the end of the pre-treatment period, animals were housed individually. At the day of treatment, animals received Al oxid C mixed with diet at ratio 1:4. After rats finished their ration in 24 hours, they were again group- caged. After treatment animals received stock diet and water ad libitum.

Duration of observation period for possible signs of intoxication: 14 days.
At the end of study (after 14 days of observations), gross necroscopy was performed on all animals.

Statistics:

No data available.

Preliminary study:

Not performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 10 000 mg/kg bw

Based on:

test mat.

Mortality:

Aluminium oxid C did not cause mortality in males and females (Wistar) rats after dietary exposure to 10000 mg/kg bw.

Clinical signs:

other: No death occurred after the treatment. At dose 10000 mg/kg, no clinical signs of intoxication were observed during the post-administration observation period. Animals appeared healthy through the observation period. No changes in behaviour were noted.

Gross pathology:

Macroscopic examination of the exposed animals did not reveal any treatment–related gross alterations.

Other findings:

Water consumption
No changes in water consumption were observed due to visual inspection of the water bottle.

Stool characteristics
No signs of diarrhea were observed. Faecal pellets were bigger and had light grey colour in tested group.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for acute oral toxicity, no classification is required.

Executive summary:

An acute oral toxicity study comparable to OECD 401 with acceptable restrictions was performed with Aluminium oxid C (white voluminous powder) in both female and male rats.

This study has been performed at the Central Institute for Nutrition and Food Research,.

Al₂O₃(as Aluminium oxid C) was administered with diet at a ratio of 1: 4 during 24 hours to each male and female (n=10) at dose level of 10000 mg/kg bw .

Parameters monitored during this study included mortality, clinical signs of possible intoxication, behavioural changes, water consumption, stool characteristics, and changes in gross pathology.Clinical observations were performed on all animals during 14 days there the Al₂O₃administration.

During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to Aluminium oxid C administration at dose 10000 mg/kg bw. 

Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

Reference 5

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

yes

Remarks:

Limited reporting on study design and results.

GLP compliance:

not specified

Test type:

other: An acute oral toxicity study based on OECD TG 420 (2001) was performed for aluminium oxide bulk material (50-200 µm) as a dose-range finding study

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: National Institute of Nutrition, Hyderabad, India
- Age at study initiation: 4 - 5 weeks
- Weight at study initiation: 90 - 100 g
- Housing: Rats were kept in polypropylene cages under controlled conditions
- Diet: Animals received a standard laboratory feed (wheat flour 2.5%; roasted Bengal gram flour 60%; skimmed milk powder 5%; casein 4%; refined ground oil 4%; salt mixture 4%; vitamin mixture 0.5%), ad libitum.
- Water: Animals received a standard laboratory water, ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 60 ± 10
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

other: 1% Tween 80 in double distilled water (DDW).

Details on oral exposure:

Al oxide was prepared for administration as suspended solutions in 1% Tween 80 and dispersed by ultrasonic vibration for 10 minutes. The suspensions were mixed thoroughly prior to dosing.

Animals were treated with 1 mL of dosing solution per 100 g body weight (in Balasubramamyam et al., 2009a ).

Doses:

Sighting study (5, 50, 300 and 2000 mg/kg bw)
A single rat was dosed with Al2O3 first with 5 mg/kg body weight (bw), if no mortality occurs, the second rat received 50 mg/kg bw, then 300 mg/kg bw and 2000 mg/kg bw.

Main acute oral toxicity study (2000 mg/kg bw)
As no mortality was observed in the treated single animals with doses 5, 50, 300 and 2000 mg/kg bw, three groups of rats (n=5/group) received a single administration of Al2O3 bulk material at dose 2000 mg/kg bw.

No. of animals per sex per dose:

Sighting study (5, 50, 300 and 2000 mg/kg bw)
1 female per dose.

Main acute oral toxicity study (2000 mg/kg bw)
5 females per group.

Control animals:

no

Details on study design:

Sighting study (5, 50, 300 and 2000 mg/kg bw)
Frequency of clinical observation in animals: not reported.
Gross necroscopy: not performed.

Main acute oral toxicity study (2000 mg/kg bw)
Frequency of clinical observation in animals: not reported.
Gross necroscopy: not performed.

Statistics:

Analysis of Variance (ANOVA) and multiple pair-wise comparisons were done using the Tukey’s test. Group mean values of each experiment were also compared by single-sided Student‘s test. P<0.05 was considered as the level of significance (in Balasubramamyam et al., 2009a).

Preliminary study:

Sighting study
No mortality and /or clinical signs of intoxication were observed in single rats received 5, 50, 300 and 2000 mg Al2O3/kg bw.

Main acute oral toxicity study
No mortality was observed in rats received 2000 mg Al2O3/kg bw.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

Sighting study
No mortality and /or clinical signs of intoxication were observed in single rats received 5, 50, 300 and 2000 mg Al2O3/kg bw.

Main acute oral toxicity study
No mortality was observed in rats received 2000 mg Al2O3/kg bw.

Clinical signs:

other: No data.

Gross pathology:

No data.

Other findings:

MN and CA study
No changes in gross pathology were noted at sacrifice.

Al2O3 distribution
Al2O3 –Bulk (50-200 µm): levels of Al oxide increased with increased dose (500, 1000 and 2000 mg/kg) but did not reach statistical significance.

Comment: 14 days after oral exposure, observed levels of Al oxide in all studied internal organs including brain were similar between all groups and comparable with the level of Al oxide in the whole blood. Based on reported findings and lack of reported measures to prevent external Al contamination, the possibility that samples were contaminated by Al from external sources could not be excluded.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

According to CLP (1272/2008/EC) classification criteria for acute oral toxicity, no classification is required.

Executive summary:

An acute oral toxicity study was performed with an aluminium oxide bulk sample (50-200 µm) in female Wistar rats in a study similar with OECD Test Guideline 420.

Aluminium oxide bulk sample with particle size 50-200 µm were administered by a single oral gavage to female rats at doses 5, 50, 300 and 2000 mg Al₂O₃/kg bw.

Parameters monitored during this study included mortality and clinical signs of intoxication. There was no mortality related to aluminium oxide oral exposure at any used dose. 

Under the conditions of this study, acute oral LD₅₀(rat) of the Al₂O₃ bulk sample with particle sizes 50-200 μm is above 2000 mg/kg bw.

Reference 6

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

supporting study

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: supporting, source, RA-A, 21645 -51 -2, Spanjers, 2009

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

In the acute oral toxicity study on the source substance (CAS 21645-51-2) in rats a LD50 value of > 2000 mg/kg bw was determined. Applying the read-across approach, the target substance (CAS 1344-28-1) is expected to be of similar acute oral toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies, and is thus sufficient to fulfil the standard information requirements set out in Annex VII, 8.5, of Regulation (EC) No 1907/2006.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

First exposure to test substance 19 Apr, 1996 to 3 May, 1996.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

other: EPA 40 CFR 158 Guideline Reference #81-3

Deviations:

yes

Remarks:

: Only one concentration was used; no justification was provided for the choice of concentration used.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

: Only one concentration was used; no justification was provided for the choice of concentration used.

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Ace Animals, Boyertown, PA
- Age at study initiation: ca. 8 – 11 weeks (born between 7 Feb and 29 Feb, 1996; received at facility 9 Apr, 1996; start date of experiment 19 Apr, 1996)
- Weight at study initiation: 219-276 g for males, 222-273 g for females
- Housing: The rats were identified using cage notation and tail marks and housed one animal per cage in suspended cages. Bedding was beneath cages and was changed at least 3x per week.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 10 day acclimation period.

ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

other: Not relevant.

Mass median aerodynamic diameter (MMAD):

>= 2.31 - <= 2.85 µm

Geometric standard deviation (GSD):

>= 2.97 - <= 3.22

Remark on MMAD/GSD:

During the experiment, the MMAD was 2.31 µm and the GSD 2.97 in the first 30 second sampling period and 2.85 µm and 3.22 in a second sampling period.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber volume: 57 liter dynamic glass chambers divided into ten non-restraining cubicles with wire screening
- Source and rate of air: The airflow exchanged the chamber volume 10 to 15 times per hour and was also recorded at 30 minute intervals during the exposure period. Chamber air flow was 30 L/min initially and at all times points during exposure except at 100 minutes when a value of 20 L/min is reported in the results.
- System of generating particulates/aerosols: To produce the test concentration, the fumed alumina was fed into a Venturi Dust Generator (Intox). Air flow was adjusted to ensure a uniform concentration of the test compound in the chamber.
- Temperature, humidity, pressure in air chamber: Chamber temperature and humidity were monitored at 30 minutes intervals during the exposure. The temperature ranged from 20.7 to 23.3 ºC and the humidity from 60 to 61% during the exposure period.


TEST ATMOSPHERE (if not tabulated)
Details on analytical verification of doses or concentrations:
A nominal concentration was calculated by dividing the amount of test substance dispensed from the dust generator during the 4 hour exposure period by the total volume of air that passed through the chamber. The amount of test material was determined gravimetrically using pre-weighed filters that sampled for 2 minutes at 3 litres per minute air flow.

Particle size MMAD (mass median aerodynamic diameter)/GSD (geometric standard deviation):
The particle size distribution was measured twice during exposure using an 8-stage Andersen cascade impactor. The mass mean aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were determined graphically using log-probit paper. During a pre-test evaluation, an MMAD of ≤4µm was required to meet the definition of “respirable” sized particles.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Single dose: 2.3 mg/L
The average gravimetrically determined concentration of test substance in the chamber air was 2.3 mg/L (sd. 0.041, n=6).

No. of animals per sex per dose:

Ten animals (5 male and 5 female) were treated.

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
Animals were observed for signs of toxicity at approximately one hour intervals during exposure, one hour post exposure and daily during the 14 day post-exposure observation period. Observations were twice daily for mortality. Body weights were recorded pre-test, weekly and at termination
- Other examinations performed:
Animals were observed for signs of toxicity, mortality and pharmacological effects.
Body weights were also recorded. Gross pathology was examined post-mortem.

Sacrifice and Pathology (methods):
BeuthanasiaR was used to sacrifice the animals.

Statistics:

No methods were used.

Preliminary study:

Not relevant.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.3 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Slope: could not be calculated.

Mortality:

There were no deaths during the exposure or 14 day post-exposure observation period.

Clinical signs:

other: All animals had closed eyes, a wet nose/mouth area and fur coated with the test material at 45 minutes, 93 minutes, 155 minutes and 215 minutes during the exposure period. At 1 hour post-exposure, only coated fur was noted, again for all animals. All an

Body weight:

The authors report normal weight gain in all males but in only 1 of the 5 females. Weight loss was observed in two females on day 7 of the post-exposure period and in another two females on day 14.

Gross pathology:

Lungs were darker than normal (score of 2) with slight or scattered red areas in one female. No other abnormalities were observed.

Body Weight (g)

Animal	Pre-test	Day 7	Day 14
1-M	265	321	349
2-M	276	319	349
3-M	266	313	342
4-M	219	271	296
5-M	274	339	387
Mean	260	313	345
sd	23.4	25.2	32.4
6-F	264	254	277
7-F	226	238	241
8-F	273	250	269
9-F	230	246	238
10-F	222	252	236
Mean	243	248	252
sd	23.7	6.3	19.3

 

The authors report normal weight gain in all males but in only 1 of the 5 females. Weight loss was observed in two females on day 7 of the post-exposure period and in another two females on day 14.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

No mortality was observed during this study, clinical signs were minor and only one animal showed lung abnormalities on necropsy. A detrimental effect on weight gain was observed in females only. The LC50 for fumed alumina is greater than 2.3 mg/L.

Executive summary:

The study by Cabot (1996) was conducted according to EPA Guidelines for Test Procedures Subdivision F, Series 81-3 and TSCA 40 CFR 798.1150. Five healthy male and five healthy female Wistar Albino rats were exposed to fumed alumina in an inhalation chamber for 4 hours. The number of animals used and the exposure duration were adequate according to the guidelines. The air concentration in the chamber, determined gravimetrically, was 2.3 mg/L.  Only one concentration was tested. The average mass median diameter was 2.58µm with a geometric standard deviation of 3.10 µm (2.31 µm, GSD 2.97 in the first 30 second sampling period and 2.85 µm, GSD 3.22 in a second sampling period). Chamber airflow, temperature (20.7 – 23.3 ºC) and humidity (60 to 61%) were monitored throughout the exposure period. Animals were observed for signs of toxicity at approximately one hour intervals during exposure, at one hour post exposure and then daily during a 14 day exposure period. Body weights were recorded pre-test, weekly and at termination.  No deaths were observed during exposure or during the 14 day post-exposure period. All animals had closed eyes, wet nose/mouth areas and fur coated with the test materials during the exposure. Observations were normal during the 14-day post-exposure period. Weight gain was normal in all the male animals. Weight loss was observed in two females on day 7 of the post-exposure period and in another two females on day 14. Lungs that were darker than normal with red areas were observed in only one female on necropsy. Based on the results of this study, the LC₅₀is greater than 2.3 mg/L. The main limitations of this study were the lack of description of the test materials and the use of only one concentration with no rationale provided for the level chosen. 

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1969, otherwise unclear.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

: only 1 hour exposure

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

other: Charles River

Sex:

male

Details on test animals or test system and environmental conditions:

Details on test animals and environmental conditions:
- Source of animals: Not reported
- Age: Not reported.
- Weights at start of exposure: The mean weight of each experimental group was reported (201g for the negative control group and 203g, 195g, 200g, and 200g for treatment groups ordered with increasing dose). Individual weights were not provided.
- Housing and environment: Not reported
- Diet and water: Not reported
- Acclimation and monitoring animal health: Not reported

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

other: Not relevant.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Limited detail was provided on the production of the test atmosphere. Briefly, the compound was aerosolized and delivered into a 100 litre exposure chamber.

The method of allocation to groups was not specified.
Particle size MMAD (mass median aerodynamic diameter)/GSD (geometric standard deviation): Not reported.

Further detail on particle characteristics (e.g. shape):
Predominantly gamma-alumina formed by hydrolysis of aluminium chloride in a flame process. (Bailey RR, Wightman JP. Interaction of gaseous hydrogen chloride and water with oxide surfaces. J Colloid Interface Sci 1979 70: 112-123.)

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Known volumes of chamber atmosphere were drawn across weighed filters, the filters were re-weighed and the air concentration of the test compound was calculated on the basis of the volume and the gravimetric measurement.

Duration of exposure:

1 h

Concentrations:

The concentrations were 0, 5.06, 5.88, 6.28 and 8.22 mg of product per litre of chamber air. The authors state that 8.22 mg/L was the highest concentration obtainable under the experimental conditions.

No. of animals per sex per dose:

10 animals were in each treated group. The control group consisted of 5 animals.

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: After the one hour exposure period, the animals were removed from the chamber and observed for 14 days. After this time, they were killed and necropsy was performed. Mortality and clinical signs appear to have been monitored daily post-exposure. During the one-hour exposure period, observation appears to have been continuous.
- Other examinations performed: Mortality, clinical sign, and gross pathology were examined. The trachea, lungs, liver and kidneys were examined for pathological changes. Body weights were determined at the start and termination of the experiment.

Statistics:

LC50, 95% CI and slope (S) were estimated from the data using the graphical log-probit method of Litchfield and Wilcoxon (1949) ( J Pharmacol Exp Ther 96: 99)

Preliminary study:

Not relevant.

Sex:

male

Dose descriptor:

LC50

Effect level:

7.6 mg/L air

Based on:

test mat.

95% CL:

6.45 - 8.95

Exp. duration:

1 h

Remarks on result:

other: Slope: 1.30

Mortality:

Mortality was observed at the highest three dose levels, reaching 50% in the group exposed to the highest levels (8.22 mg/L). Deaths occurred either during or shortly after exposure.

Clinical signs:

other: The clinical symptoms observed were consistent with respiratory distress. The surviving animals were described as showing only “slight” toxic effects and good recovery by the end of the 14 day observation period.

Body weight:

The authors report only a slight effect on weight gain. The statistical or biological significance of the difference was not mentioned.

Gross pathology:

A greater amount of discolouration was observed on the surface of lungs of treated animals compared with control animals. A “slight” increase in the number of lesions on the lungs of the test animals was also reported – although individual data or further detailed was not provided. Animals that died were found to have a white gel in their trachea and stomachs. Their stomachs were also gas-filled and enlarged. The liver and kidney showed no difference between the treated and control animals on macroscopic examination.

Mortality

Analytical concn.	Air flow (l.min)	Mortality	Time
0	-	0/5	-
5.06	10	0/10	-
5.88	18	1/10	At 45 minutes of exposure
6.28	18	3/10	3 deaths at 35 mins, 50 mins, 60 mins of exposure.
8.22	15	5/10	3 deaths at 10 minutes into the post-exposure period; 2 deaths at 20 minutes after cessation of exposure

 Mortality was observed at the highest three dose levels, reaching 50% in the group exposed to the highest levels (8.22 mg/L). Deaths occurred either during or shortly after exposure. 

Clinical Signs

Analy-tical concn.	Time (min)	During exposure	Time	Post-exposure
0	-	None	-	None
5.06	5	Preening, mastication type movements.	1-2 days	Loss of hair
	7	Partially closed eyes
	8	Inactive and sneezing
	23	Gasping
	26	Piloerection
	35	Brown discharge around nose
	37	Slow and deep respiration
5.88	1	Preening	2 days	Loss of hair
	4	Slow and deep respiration and partially closed eyes
	6	Mastication-like movements
	8	Gasping
	12	Piloerection
	19	Nasal discharge
	45	Death (n=1)
6.28	1	Preening	1 day	Brown crust around nose
	3	Inactive
	4	Rapid and deep respiration
	11	Slow and deep respiration
	13	Brown nasal discharge
	14	Gasping and piloerection
	35	Death (n=1)
	50	Death (n=1)
	60	Death (n=1)
8.22	1	Active preening	8 min	Convulsive-like movement
	3	Sneezing	10 min	Death (n=3)
	5	Partially closed eyes	14 min	Convulsive-like movements
	7	Gasping	20 min	Death (n=2)
	10	Slow and deep respiration	2 days	Loss of hair
	12	Nasal discharge
	19	Piloerection
	28	Edema of face
	33	ataxia

 

The clinical symptoms observed were consistent with respiratory distress. The surviving animals were described as showing only “slight” toxic effects and good recovery by the end of the 14 day observation period.

Body Weight

Analy-tical concn.	Avg. body wt (t=0)	Avg. body wt (t=end)	Change in body wt
0	201	319	118
5.06	203	287	84
5.88	195	299	104
6.28	200	300	100
8.22	200	292	92

 

The authors report only a slight effect on weight gain. The statistical or biological significance of the difference was not mentioned.

Details on Results:

The authors of the study suggest that the deaths were likely due to suffocation from blockage of air passages by gel formed from the test substance in the high humidity of the air passages.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

Mortality occurred either during or shortly after exposure and the clinical symptoms observed were consistent with respiratory distress. A slight (otherwise unspecified) effect on weight gain was reported. The surviving animals were described as showing only “slight” toxic effects and good recovery by the end of the 14 day observation period. A greater amount of discolouration was observed on the surface of lungs of treated animals compared with control animals. A “slight” increase in the number of lesions on the lungs of the test animals was also reported – although individual data or further detailed was not provided. The LC50 estimated from this study based on only one hour of exposure was 7.6 mg/L (95% CI: 6.45 – 8.95 mg/L). This study report lacked detail on the descriptions of the test compound (critically on the particle size, and also the shape and purity), the chamber conditions and animal husbandry, and the results from the examination of the gross pathology of the trachea, lungs, kidney and liver.

Executive summary:

The objective of the pre-guideline acute inhalation toxicity study conducted by Laboratories (Cabot, 1969) was “to determine the acute inhalation toxicity and calculate the LC50, the confidence limits and slope function of the test material.”  Malerats (age unspecified) were exposed for one hour to concentrations of 0, 5.06, 5.88, 6.28 and 8.22 mg of aluminium oxide (fumed alumina) per litre of air in inhalation chambers. The authors state that 8.22 mg/L was the highest concentration obtainable under the experimental conditions.The mean weight of each experimental group was reported (201g for the negative control and 203g, 195g, 200 g and 200 g for the treatment groups, ordered with increasing dose). Individual weights were not provided. Limited detail was provided on the production of the test atmosphere. Briefly, the compound was aerosolized and delivered into a 100 litre exposure chamber. The concentrations of test material were analytically verified by drawing known volumes of chamber atmosphere across weighed filters. The filters were then re-weighed and the average concentration of the test compound calculated on the basis of the volume and the gravimetric measurement. After the one hour exposure period, the animals were removed from the chamber and observed for 14 days. After this time, they were killed and necropsy was performed. Mortality and clinical signs appear to have been monitored daily post-exposure. During the one-hour exposure period, observation appears to have been continuous. The trachea, lungs, liver and kidneys were examined for gross pathological changes. Body weights were determined at the start and termination of the experiment. The LC50, 95%CI and slope (S) were estimated from the data using the graphical log-probit method of Litchfield and Wilcoxon (1949) ( J Pharmacol Exp Ther 96: 99). Mortality was observed at the highest three dose levels, reaching 50% in the group exposed to the highest levels (8.22 mg/L). Deaths occurred either during or shortly after exposure. The clinical symptoms observed were consistent with respiratory distress. The surviving animals were described as showing only “slight” toxic effects and good recovery by the end of the 14 day observation period. The authors report only a slight effect on weight gain. The statistical or biological significance of the difference was not mentioned. A greater amount of discolouration was observed on the surface of lungs of treated animals compared with control animals. A “slight” increase in the number of lesions on the lungs of the test animals was also reported – although individual data or further detailed was not provided. Animals that died were found to have a white gel in their trachea and stomachs. Their stomachs were also gas-filled and enlarged. The liver and kidney showed no difference between the treated and control animals on macroscopic examination. The authors of the study suggest that the deaths were likely due to suffocation from blockage of air passages by gel formed from the test substance in the high humidity of the air passages. The LC50 estimated from this study based on one hour of exposure was 7.6 mg/L (95% CI: 6.45 – 8.95 mg/L). This study report lacked some detail on the test substance (information obtained from sponsor), the chamber conditions and animal husbandry, and also the results from the examination of the gross pathology of the trachea, lungs, kidney and liver. The duration of exposure was only one hour. The number of animals and the reporting of the results that were included were adequate. 

Reference 3

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

26. - 29. Feb. 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. (No justification given for concentration tested, study was terminated shortly after exposure (3 days), observation period should have lasted for 14 days.)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

short period of post exposure observations and no justification for test concentration given

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Deviations:

yes

Remarks:

short period of post exposure observations and no justification for test concentration given

GLP compliance:

yes

Test type:

standard acute method

Species:

rat

Strain:

other: naive albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc., Houston, Texas
- Age at study initiation: young adult
- Weight at study initiation: males (272 - 337 g), females (204 - 264 g)
- Fasting period before study:
- Housing: 1 - 3 per cage (males separated from females) in suspended, wire bottom, stainless steel cages, during exposure animals were kept one per cage
- Diet: Purina Formulab Chow #5008, ad libitum except during exposure period
- Water: tap water, ad libitum from automatic water system, except during exposure period
- Acclimation period: at least one week

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel dynamic flow inhalation chamber
- Exposure chamber volume: 500 L
- Method of holding animals in test chamber: in cages, with one animal per cage
- Source and rate of air: filtered air
- Method of conditioning air: concentrated aerosol was diluted with filtered air and drawn into exposure chamber
- System of generating particulates/aerosols: The aerosol was generated using a Gem T Trost Air Mill coupled with a motor driven revolving disc delivery system and then combined with filtered air and drawn into the exposure chamber. Air flow in the chamber was maintained through the use of a calibrated critical orifice.
- Method of particle size determination: was done using an Andersen cascade impactor
- Temperature, humidity in air chamber: control group - temp.: 21 - 22°C; humidity: 77 - 86 %, treatment group - temp.: 19.5 - 20.5°C; humidity: 67-76 %

TEST ATMOSPHERE
- Brief description of analytical method used: The concentration of test material in the exposure atmosphere was determined gravimetrically twice per hour and nominally at the end of the exposure period. The gravimetric concentration was determined by passing a known volume of exposure air through a pre-weighed filter and the dividing the amount of test material deposited on the filter by the volume of air which passed through the filter. The nominal concentration was determined by dividing the loss in the weight of the test material after the exposure by the total volume of air which passed through the chamber.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: see table1 under any other informations on materials and methods including tables
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): at 2,75 hours - 5.423 µm/3.038 µm; at 4 hours - 4.645 µm/3.162 µm

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: not given

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetricalls

Duration of exposure:

4 h

Concentrations:

5.09 mg/L

No. of animals per sex per dose:

10 males and 10 females

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 72 hours post exposure
- Frequency of observations and weighing: weighing - before and during the post-exposure period, general observations, toxic signs and mortality were recorded at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 24 hours and 2 and 3 days post exposure
- Necropsy of survivors performed: yes (at 24 and 72 hours after exposure)
- Other examinations performed: clinical signs, body weight, histopathology of nasal turbinates, lung and trachea

Statistics:

Particle size distribution was calculated by using Probit analysis, Finney, D.J.: Probit analysis, 3rd Edition, Chapter 3 and 4, 1971, Cambridge University Press; Statistical analysis were conducted using 48 K APPLE II PLUS computers

Preliminary study:

Not available

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.09 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No deaths were observed in Al-exposed male and female rats at any observation time.

Clinical signs:

other: control animals did not show any clinical signs during the study. Treated animals showed piloerection, decreased activity and ptosis (see summary table3). Piloerection and decreased activity were slightly more prominent in females than in males. All signs

Body weight:

No changes in body weight were observed following inhalation exposure for 4 hours to high concentration of Catapal Alumina Fines at 24 and 72 hours post exposure.

Gross pathology:

No observable abnormalities were recorded during gross necropsy examination after 24 and 72 hours of post exposure in both males and females.

Other findings:

- Organ weights: not reported
- Histopathology: No histopathological abnormalities were observed in nasal turbinate, lungs and trachea during microscopic histological examination in any of the treated animals.

Table3: Clinical signs observed

Reactionand severity	Time after exposure period started
	Hours*
	0.5	1.0	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	24	48	72
Males
Piloerection (s-e)	5	5	5	5	5	5	**	**	10	10	10	0	0	0	0
Acitivty decreased (s)	0	5	5	5	5	5	**	**	10	10	0	0	0	0	0
Ptosis (s)	0	5	5	5	5	5	**	**	0	0	0	0	0	0	0
Females
Piloerection (s-e)	5	5	5	5	5	5	**	**	10	10	10	10	0	0	0
Activity decreased (s)	0	5	5	5	5	5	**	**	10	10	10	0	0	0	0
Ptosis (s)	0	5	5	5	5	5	**	**	0	0	0	0	0	0	0

Severity signs: v-very slight, s-slight, m-moderate, e-extreme (no details provided regarding severity ranking in the exposed animals)

*- Due to chamber design only ten animals (5 males, 5 females) could be observed during exposure period.

**- Unable to observe animals at this point due to excessive collection of test material of the chamber window.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

No differences in susceptibility between sexes were observed in body weight, clinical and histopathological findings in an inhalation acute toxicity study for Catapal Alumina Fines under conducted experimental conditions. Some caution is required in interpreting results, due to a short period of post exposure observation (3 days instead of 14).

Reference 4

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Sex:

male

Dose descriptor:

LC50

Effect level:

> 0.888 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: key, source, RA-A, 7429-90-5, Thomson et al., 1986

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

In the acute inhalation toxicity studies on the source substance (CAS 1334-28-1) in rats a LD50 value of >0.888 mg/L air was determined. Applying the read-across approach, the target substance (CAS 1344-28-1) is expected to be of similar acute inhalation toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies, and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.5.2, of Regulation (EC) No 1907/2006.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance does not meet the criteria for classification as acute toxicity or STOT SE by the oral route and no systemic effects have been observed in in vivo studies with dermal exposure (e.g. skin irritation, skin sensitisation)

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral route:

The available data are adequate to meet the REACH information requirements for aluminium oxide with respect to acute toxicity. According to the reported results (acute oral toxicity study, Hazleton Laboratories, USA 1969; Central Institute for Nutrition and Food Research, Germany 1979a; Central Institute for Nutrition and Food Research, Germany 1979b, Central Institute for Nutrition and Food Research, Germany 1979c; IUCLID, Aluminium Oxide Dataset, 2000; and Balasubramanyam et al., 2009b and Balasubramanyam et al., 2009a), the oral LD₅₀ for aluminium oxide is above 2000 mg/kg bw in both female and male rats.

The results were supported by an OECD 423 study with aluminium hydroxide. A detailed rationale and justification for the analogue read-across approach is provided in the technical dossier (see IUCLID section 13.2).

 

An acute oral toxicity study comparable to OECD 401 was performed with fumed alumina in female and male rats. This study has been performed at the Hazelton Laboratories, Inc..Fumed alumina was administered by a single oral gavage to seven groups of five males and five females per group at dose levels of 1000, 1590, 2510, 3980, 6310, 10000 and 15900 mg/kg bw after an overnight food withdrawal (Butter, 1969). Parameters monitored during this study included mortality and clinical signs of possible intoxication. Clinical observations were performed on all animals immediately after dosing, at 1, 4 and 24 hours after dosing and daily for 14 days thereafter. During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose range from 1000 mg/kg to 10000 mg/kg bw. Clinical signs of depression, laboured respiration, and piloerection (males) were noted immediately and hunched appearance was noted at 24 hours post-administration of the highest dose 15900 mg/kg. No significant sex differences were noted among animals in the sensitivity to the administered compound or during the recovery period. Animals appeared normal by day 7 (females) and day 8 (males). Macroscopic examination at the end of the observation period did not reveal any aluminium-related changes of the internal organs of the aluminium treated animals compared to the control group. Under the conditions of this study, the acute oral median lethal dose (LD50) of the fumed alumina is above 15900 mg/kg bw in both females and males rats.

 

A study for acute oral toxicity was performed with various aluminium oxide nanoscale samples with particle sizes 30 and 40 nm and bulk sample (50 - 200 µm) in female Wistar rats in a study similar with OECD Test Guideline 420 (Balasubramanyam, 2009).Aluminium oxide nanoparticles with particle size 30 nm and 40 nm and bulk sample with particle size 50 - 200 µm were administered by a single oral gavage to female rats at doses 5, 50, 300 and 2000 mg Al2O3/kg bw. Parameters monitored during this study included mortality and clinical signs of intoxication. There was no mortality related to aluminium oxide oral exposure at any used dose. Under the conditions of this study, acute oral LD50 (rat) of the all type of Al2O3 bulk sample with particle sizes 50 -200 μm and all Al2O3 nano-particles is above 2000 mg/kg bw. 

 

Aluminium oxide (granulated solid product) was tested for acute oral toxicity in female and male rats equivalent to OECD Guideline 401(Nagy, 1979).This study has been performed at the Central Institute for Nutrition and Food Research, Germany. Al2O3 was administered by a single oral gavage to ten males and ten females per group at dose level of 10,000 mg/kg bw after an overnight food withdrawal. Parameters monitored during this study included mortality, clinical signs of possible intoxication, and changes in gross pathology. Clinical observations were performed on all animals during 14 days there the Al2O3 administration. During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose 10000 mg/kg bw. No significant sex differences were noted among animals in the sensitivity to the administered compound. Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

An acute oral toxicity study comparable to OECD 401 with acceptable restrictions was performed with aluminium oxide (granulated solid product) in both female and male rats (Spanjers, 1979). This study has been performed at the Central Institute for Nutrition and Food Research. Al2O3 was administered by a single oral gavage to ten males and ten females per group at dose level of 10000 mg/kg bw after an overnight food withdrawal. Parameters monitored during this study included mortality, clinical signs of possible intoxication, and changes in gross pathology. Clinical observations were performed on all animals during 14 days there the Al2O3administration. During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium oxide administration at dose 10000 mg/kg bw. No significant sex differences were noted among animals in the sensitivity to the administered compound. Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

In addition, an acute oral toxicity study comparable to OECD 401 with acceptable restrictions was performed with Aluminium oxid C (white voluminous powder) in both female and male rats (Spanjers, 1979). This study has been performed at the Central Institute for Nutrition and Food Research. Al2O3 (as Aluminium oxid C) was administered with diet at a ratio of 1: 4 during 24 hours to each male and female (n = 10) at dose level of 10000 mg/kg bw. Parameters monitored during this study included mortality, clinical signs of possible intoxication, behavioural changes, water consumption, stool characteristics, and changes in gross pathology. Clinical observations were performed on all animals during 14 days there the Al2O3 administration. During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to Aluminium oxid C administration at dose 10000 mg/kg bw. Macroscopic examination at the end of the observation period did not reveal any changes of the internal organs associated with the aluminium treatment.

The acute oral toxicity study (limit test) of aluminium hydroxide (SH-20 Muster) in female CRL (WI)BR rats was assessed in a study performed equivalent to OECD 423 (Spanjers, 2009).This study has been performed in accordance with the OECD 423 (17thDecember 2001), Commission Regulation (EC) No 440/2008, B.1 tris (L 142, 30 May 2008), OPPTS 870.1100 (EPA 712-C-98-190, August 1998) and the Principles of Good Laboratory Practice (Hungarian GLP Regulations: 9/2001.III. 30). Aluminium hydroxide was administered by a single oral gavage to animals after an overnight food withdrawal at a concentration of 2000 mg/mL in vehicle (PEG 400) with a treatment volume of 10 mL/kg bw. Parameters monitored during this study included mortality, clinical signs, body weight and body weight gain. Clinical observations were performed on all animals at 30 minutes, 1, 2, 3, 4 and 6 hours after dosing and daily for 14 days thereafter. Body weight was measured on days 1, 0 and 7 and before necropsy. Necropsy was performed on all animals on Day 14. During the 14 days of the observation period, there was no mortality or clinical signs of intoxication related to aluminium hydroxide administration at 2000 mg/kg bw. Soft faeces were recorded in all treated animals at first day of administration. It was no differences in body weight gains between aluminium treated and control animals. Macroscopic examination at the end of the observation period did not reveal any aluminium-related changes of the internal organs of the aluminium treated animals compared to the control group. Under the conditions of this study, the acute oral median lethal dose (LD50) of the aluminium hydroxide/SH-20 Muster was above 2000 mg/kg bw in female CRL:(WI)BR rats.

Prabhakar et al. (2011) investigated the acute oral toxicity of bulk Al oxide powder (purity 90% and 50 - 200 µm, as reported by Balasubramanyam et al., 2009) and two nanoscale aluminium oxide samples (Al2O 330 nm and Al2O 340 nm, purity > 90%) in fasted female Wistar rats (8 - 10 weeks old, 10 animals per group) given a single dose of 500, 1000 and 2000 mg Al2O3/kg bw by gavage. Control groups (10 animals per group) received the equal volume of 1% Tween-80. The samples for administration were prepared as suspended solutions in 1% aqueous Tween 80 and dispersed by ultrasonic vibration for 10 min. Animals were treated with 1 mL of dosing solution per 100 g body weight (as described in Balasubramanyam et al., 2009). All of the animals were kept under controlled housing and environmental conditions and were fed a commercial pellet diet and drinking water ad libitum. All procedures were conducted in accordance with Institutional (National) Animal Care guidelines.

No clinical signs of intoxication or deaths were observed during 14 days of the observation period and no statistically significant changes in body weight, food intake or organ weight were found (data not shown). On day 3 after exposure, bulk Al oxide powder-treated rats showed a statistically significant decrease in the reduced gluthatione (GSH) content in the brain, liver and kidney compared to the 1% Tween 80-treated controls. In the liver, acute oral exposure to bulk Al oxide powder was associated with statistically significant reductions in superoxide dismutase (SOD) (1000 and 2000 mg/kg) and glutathione reductase (GR) activity (1000 and 2000 mg/kg) and increased catalase (500, 1000 and 2000 mg/kg) and gluthatione S-transferase (GST) activity (2000 mg/kg); in the kidney there was a statistically significant increase in malondialdehyde (MDA) levels, decreased glutathione reductase activity (2000 mg/kg, respectively) and increased catalase and GST activities (2000 mg/kg, respectively ) compared to the controls. No statistically significant changes in these parameters in the bulk Al oxide powder-treated rats were found on day 14 after exposure. No changes in the oxidative stress biomarkers were observed in the heart of the bulk Al oxide powder-treated animals at either time interval. On day 14, the brain, liver, kidney and heart of the bulk Al oxide powder-treated and control animals were subjected to histopathological examination; no histological changes in the liver, brain, heart or kidney were observed. Treatment of animals with nanoscale Al oxide particles induced a more pronounced response in the studied biochemical outcomes compared to the bulk Al oxide powder-treated animals. Both nanoscale samples changed oxidative stress biomarkers in a dose-dependent manner, in comparison to no response after oral dosing with the bulk Al oxide powder. Significant hepatic changes were observed in rats treated with 2000 mg Al2O3 (30 and 40 nm)/kg bw and these included dilated central vein, hepatic artery, hepatic portal vein and bile tract. The lack of mortality precluded estimation of an oral LD50 value. The authors suggested that, under the conducted experimental conditions, the acute oral median lethal dose (LD50) of a bulk Al oxide powder and the nanoscale Al2O3 samples (30 and 40 nm) was greater than 2000 mg Al2O3/kg bw in female rats. There were no evident clinical signs of intoxication related to oral exposure to aluminium at 500, 1000 or 2000 mg/kg bw. Only limited details were available on physical and chemical characteristics of the Al oxide bulk form and nanoparticles, lack of a control group (treated with drinking water), few details regarding preparation of dosing solutions and analytical verification of administered dose and the terms of the conducted observations and examinations were not provided. Relatively limited numbers of animals (n = 5) were used in the biochemical assays and histopathological examinations, no control group available for a second time interval (at 14 days of the study) and only a limited number of toxicological endpoints were studied. The results contribute to the evidence of low acute oral toxicity (e.g., mortality) of Al oxide independent of the particle size. However, methodological deficiencies and insufficient description of purities and particle sizes decrease the confidence in the reported results and reduce the utility of the findings for risk assessment. Based on the overall study design and noted limitations, a Klimisch Score of 3 is considered appropriate.

 

Rawy et al. (2012) reported on the acute oral toxicity and toxicokinetic parameters [e.g., the maximum concentration (Cmax), maximum time to peak concentration (Tmax, days), the elimination rate constant (Lz, day 1), the elimination half-life time (t1/2,day), mean residence time (MRT, day) and clearance (Cl, L/day)] of Al in the liver, kidney, brain, intestine (µg/g wet wt.) and serum (µg/ml)] after a single oral dose of Al chloride hexahydrate (AlCl3•6H2O) in adult albino rats (120 ± 20 g., 5 animals per group). To estimate an oral LD50, the rats received a single dose of 0.5, 1.25, 2.5, 3.5 or 4 g AlCl3/kg bw by gavage. Mortality in each group was recorded through 24 hr post-exposure. The LD50 was calculated as 3.5 g AlCl3/kg bw (no other details available). This study has a number of the limitations: no details were available on type of vehicle used to prepare the AlCl3 solutions. The LD50 was estimated based on a 24 hr post-exposure observation instead of the standard 14 days. The authors expressed the LD50 value in mg AlCl3 and did not convert the value to mg Al/kg bw to facilitate comparison to the acute oral LD50 in rats (370 mg Al/kg bw) for AlCl3•6H2O reported by Llobet et al. (1987). Comparing the Llobet et al. (1987) oral LD50 as elemental Al to that reported by Rawy et al. (2012) (707 mg Al/kg bw) shows that the more recent value is about one-half as potent as that reported previously. As such, it is not clear whether this marked difference is due to the abbreviated post-exposure observation period used by Rawy et al. (2012) or to other factors. Due to these limitations, the reported results should be interpreted with caution and a Klimisch Score of 3 was assigned. The results are of only limited utility for human health risk assessment.

 

Based on the available data, it is proposed that aluminium oxide need not be classified for acute oral toxicity.

 

Dermal route:

In a human dermal absorption study, Flarend et al. (2001) showed minimal absorption of aluminium into the systemic circulation on single application with occlusion of aluminium chlorohydrate to underarms. Based on urine measurements, 0.01% of the applied aluminium was absorbed showing that aluminium does not cross the dermal barrier effectively.

A dermal study is not necessary in accordance with Column 2 of Annex VIII, Section 8.5, of Regulation (EC) No 1907/2006.

 

Inhalation route:

Human Studies

No epidemiological studies were identified that examined acute irritative effects, for example cross-shift lung function changes or respiratory symptoms, on inhalation exposure to aluminium metal dust or powder.  

 

Animal Studies

Stillmeadow Inc. (1990) conducted a GLP-compliant acute toxicity inhalation study in rats for Vista Chemical Company using Vista Catapal Alumina. The objective of this study was to determine the acute inhalation irritation potential of the Catapal Alumina Fines (fine powder, MMAD: 4.64 microns (geometric standard deviation - 3.16 microns)) (LOT 2169 V3612B). Ten male and ten female rats were exposed for 4 h to an aerosol generated from the undiluted test material (fine powder) at a concentration of 5.09 mg/L (equivalent to 5,090 mg/m³). During exposure Al- treated and control groups were placed in individual, stainless steel cages within a 500 L stainless steel, New York University design, dynamic flow inhalation chamber. Twenty rats (negative control group) were housed in the same manner in an identical inhalation chamber for 4 h without exposure to the test material. All animals were returned to their laboratory cages within 24 h after termination of exposure. The aerosol was generated by using a Gem T Trost Air Mill coupled with a motor driven revolving disc delivery system and then combined with filtered air and drawn into the exposure chamber. Air flow into the chamber was maintained through the use of a calibrated critical orifice. Air flow was monitored at 30 min intervals during exposure and it was sufficient to keep adequate oxygen content of the exposure atmosphere. Temperature and humidity were monitored at 30 min intervals during exposure using a Taylor wet bulb/dry bulb hydrometer located in the exposure chamber. The actual exposure concentration of test material at the breathing zone of the animals was determined gravimetrically 2 times per hour. The nominal concentration was determined by dividing the loss in weight of the test material after the exposure by the total volume of air passed through the chamber. Particle size determinations were performed using an Andersen cascade impactor. The exposure concentration determined gravimetrically was confirmed as 5.09 mg/L. The mass median aerodynamic diameter (MMAD) of the Catapal Alumina fine powder particles (administered undiluted as an aerosol) was 4.64 microns (geometric standard deviation - 3.16 microns) (4 hr distribution data). Clinical observations were performed on all animals daily, before and after exposure. The animals were weighed before study and at 24, 48 and 72 h post-exposure. The general appearance of Al-treated and control animals, clinical signs and time of death (if occurred) were recorded at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 24 h and at 2 and 3 days post-exposure. To evaluate pulmonary changes over time, some animals were sacrificed at one or at 3 days after the termination of exposure. The gross necropsy examination was conducted on each of the Al-treated and control animals (5/5 males and 5/5 females were randomly selected from Al treated and control groups) at 24 and 72 h after exposure, respectively. Nasal turbinates, lungs and trachea from all Al-exposed and control animals were removed and fixed in 10% neutral buffered formalin for microscopic examination.

No mortality was observed in male or female rats following acute inhalation exposure to undiluted test material as an aerosol at 5.09 mg/L for 4 h during 3 days of the post-exposure observation period. Clinical signs (piloerection) were noted in male and female rats during exposure and in all males and females at 1.5 and 2.0 h post-exposure, respectively. Decreased physical activity was observed in the treated male and female rats during exposure and at 1.0 and 1.5 h post- administration, respectively. Ptosis was observed in the treated male and female rats during the exposure period only. All animals appeared to be normal and no abnormal signs were observed at 24, 48 and 72 h post-administration and no changes in body weights were noted during the post-exposure observation period. Macroscopic examination at the end of the 24 and 72 h observation periods did not reveal any treatment -related changes of the internal organs compared to the control. There were no histopathological changes in the nasal turbinates, trachea and lungs of the Catapal Alumina exposed animals. The use of both sexes revealed no significant differences in gender sensitivity. Because no mortality was observed in either Al-treated male or female rats, the results do not allow estimating the LC50. The authors suggested that the acute inhalation LC50 for Catapal Alumina Fines is greater than 5.09 mg/L (5,090 mg/m³).

Overall, this GLP compliant study was well-reported and it was well-conducted. The main goal of the study was to determine the acute inhalation irritation potential of the Catapal Alumina Fines. Although no regulatory guideline was mentioned explicitly, the study appears to have been conducted to conform generally to guidance criteria on acute inhalation toxicity testing (OECD TG 39, OECD TG 436 and OECD TG 403). The 4 h exposure period conforms to acute inhalation toxicity guidelines and sufficient numbers of animals of both sexes were used. Chamber atmosphere samples were taken from the vicinity of the animals’ breathing zone. The airflow was monitored at regular intervals to detect possible changes in the exposure concentrations. Deviation of the individual chamber concentration samples from the mean chamber concentration did not exceed 20%. In addition, the mass concentration obtained by particle size analysis was within reasonable limits of the mass concentration obtained by filter analyses which suggests that were no considerable sampling errors. Concentrations were gravimetrically verified. Clinical signs observed in all male and female rats during exposure period were short-term and reversible and included decreased activity, piloerection and ptosis. These clinical signs were not observed in Al -exposed male and female rats at 24, 48 or 72 h after the termination of the exposure. No signs of respiratory irritation were observed in male or female rats following an acute inhalation of Catapal Alumina Fines at 5.09 mg/L (5090 mg/m³). The authors suggested that the acute inhalation LC50 for Catapal Alumina Fines was greater than 5.09 mg/L when administered undiluted as aerosol to albino rats. However, some caution is required in interpreting results given the short post-exposure observation (3 days instead of 14 days) period. Based on the overall study design and limitations, a Klimisch Score of 2 (reliable with restrictions) is appropriate for this study.

 

The objective of the pre-guideline acute inhalation toxicity study conducted by Laboratories (Cabot, 1969) was “to determine the acute inhalation toxicity and calculate the LC50, the confidence limits and slope function of the test material.”  Male rats (age unspecified) were exposed for one hour to concentrations of 0, 5.06, 5.88, 6.28 and 8.22 mg of aluminium oxide (fumed alumina) per litre of air in inhalation chambers. The authors state that 8.22 mg/L was the highest concentration obtainable under the experimental conditions. The mean weight of each experimental group was reported (201 g for the negative control and 203 g, 195 g, 200 g and 200 g for the treatment groups, ordered with increasing dose). Individual weights were not provided. Limited detail was provided on the production of the test atmosphere. Briefly, the compound was aerosolized and delivered into a 100 litre exposure chamber. The concentrations of test material were analytically verified by drawing known volumes of chamber atmosphere across weighed filters. The filters were then re-weighed and the average concentration of the test compound calculated on the basis of the volume and the gravimetric measurement. After the one hour exposure period, the animals were removed from the chamber and observed for 14 days. After this time, they were killed and necropsy was performed. Mortality and clinical signs appear to have been monitored daily post-exposure. During the one-hour exposure period, observation appears to have been continuous. The trachea, lungs, liver and kidneys were examined for gross pathological changes. Body weights were determined at the start and termination of the experiment. The LC50, 95% CI and slope (S) were estimated from the data using the graphical log-probit method of Litchfield and Wilcoxon (1949) (J Pharmacol Exp Ther 96: 99). Mortality was observed at the highest three dose levels, reaching 50% in the group exposed to the highest levels (8.22 mg/L). Deaths occurred either during or shortly after exposure.  The clinical symptoms observed were consistent with respiratory distress. The surviving animals were described as showing only “slight” toxic effects and good recovery by the end of the 14 day observation period. The authors report only a slight effect on weight gain. The statistical or biological significance of the difference was not mentioned. A greater amount of discolouration was observed on the surface of lungs of treated animals compared with control animals. A “slight” increase in the number of lesions on the lungs of the test animals was also reported – although individual data or further detailed was not provided. Animals that died were found to have a white gel in their trachea and stomachs. Their stomachs were also gas-filled and enlarged. The liver and kidney showed no difference between the treated and control animals on macroscopic examination. The authors of the study suggest that the deaths were likely due to suffocation from blockage of air passages by gel formed from the test substance in the high humidity of the air passages.  The LC50 estimated from this study based on one hour of exposure was 7.6 mg/L (95% CI: 6.45 – 8.95 mg/L). This study report lacked some detail on the test substance (information obtained from sponsor), the chamber conditions and animal husbandry, and also the results from the examination of the gross pathology of the trachea, lungs, kidney and liver. The duration of exposure was only one hour. The number of animals and the reporting of the results that were included were adequate. 

 

The study by Cabot (1996) was conducted according to EPA Guidelines for Test Procedures Subdivision F, Series 81-3 and TSCA 40 CFR 798.1150. Five healthy male and five healthy female Wistar Albino rats were exposed to fumed alumina in an inhalation chamber for 4 hours. The number of animals used and the exposure duration were adequate according to the guidelines. The air concentration in the chamber, determined gravimetrically, was 2.3 mg/L.  Only one concentration was tested. The average mass median diameter was 2.58µm with a geometric standard deviation of 3.10 µm (2.31 µm, GSD 2.97 in the first 30 second sampling period and 2.85 µm, GSD 3.22 in a second sampling period). Chamber airflow, temperature (20.7 – 23.3 °C) and humidity (60 to 61%) were monitored throughout the exposure period. Animals were observed for signs of toxicity at approximately one hour intervals during exposure, at one hour post exposure and then daily during a 14 day exposure period. Body weights were recorded pre-test, weekly and at termination.  No deaths were observed during exposure or during the 14 day post-exposure period. All animals had closed eyes, wet nose/mouth areas and fur coated with the test materials during the exposure. Observations were normal during the 14-day post-exposure period. Weight gain was normal in all the male animals. Weight loss was observed in two females on day 7 of the post-exposure period and in another two females on day 14. Lungs that were darker than normal with red areas were observed in only one female on necropsy. Based on the results of this study, the LC50 is greater than 2.3 mg/L. The main limitations of this study were the lack of description of the test materials and the use of only one concentration with no rationale provided for the level chosen. A Klimisch Score of 2 (reliable with restrictions) is considered appropriate.

Further studies on acute inhalation toxicity with aluminium metal are available and used for read-across. A detailed rationale and justification for the analogue read-across approach is provided in the technical dossier (see IUCLID section 13.2).

Thomson et al. (1986) conducted a study in male Fischer 344 rats (10 - 12 weeks old) to investigate and compare the acute inhalation toxicity of aluminium flake and brass flake dusts. Both were irregularly shaped flake dusts coated with <2% palmitic and stearic acids to facilitate the milling process in manufacture. Two experiments were conducted: one with observations at 24 hours and 14 days post-exposure, the other with additional groups observed at 3 and 6 months post-exposure, in order to examine longer term effects of the acute exposure. The animals were exposed to the dust for 4 hours. During the exposure period, the animals were placed in compartmentalized wire cages without food, water or bedding in temperature - (22 ºC ± 2 ºC) and humidity - (30 to 70%) controlled chambers. The test atmospheres were produced using a Metronics Model #3 aerosol generator. Nominal concentrations for the aluminium powder were 10, 50, 100, 200 and 1000 mg/m³. The corresponding concentrations determined gravimetrically were 9.16, 47.3, 111, 206 and 888 mg/m³. The MMAD for the aluminium powder was 1.58 µm (geometric mean diameter from microscopic analysis = 2.82 ± 0.26 µm). All animals were examined for toxic signs before and after exposure and daily during the post-exposure period. The animals were weighed at weekly intervals during the experimental and post-exposure periods. Pulmonary function measurements were conducted at 24 hours, 14 days, 3 months and 6 months post-exposure. Bronchopulmonary lavage was conducted and the BALF analysed for total cell counts, differential cell counts, and biochemical parameters (total protein and levels of glucose-6-phosphate dehydrogenase (G-6-PD), lactate dehydrogenase (LDH), and alkaline phosphatase (ALKP)). Blood samples were also collected by cardiac puncture at each timepoint post-exposure for the analysis of copper, zinc, and aluminium.  After blood collection, rats were necropsied and the following examinations performed: total body weight, organ weight (heart, lung, kidneys, gonads), gross and microscopic pathology of nasal air passages, trachea, lungs and hilar lymph nodes. No mortality was observed even at the highest aluminium flake concentration. No toxic signs were observed and there were no changes in measurements of lung function even at the highest dose (1000 mg/m³).  At concentrations greater than 10 mg/m³, an increase in polymorphonuclear neutrophils in the bronchoalveolar lavage was observed at 24 hours, typical of a mild acute inflammatory response. Increases in lactate dehydrogenase, alkaline phosphatase and total protein that persisted to 3 months provide evidence for a chronic irritant response in the presence of insoluble aluminium flakes retained in the lungs. These changes were not observed at the lowest dose level, 10 mg/m³. Multifocal microgranulomas were observed in terminal airways and alveolar septae in the 200 and 1000 mg/m³ dose groups at 14 days, 3 months and 6 months. Black particulate material was observed in the hilar lymph nodes at 14 days and also later timepoints suggesting clearance by alveolar macrophages. The acute inflammatory response to aluminium flakes was less dramatic than those for more soluble brass dust. The brass dust, however, did not exhibit evidence of a chronic irritant response, effects were resolved by 14 days post-exposure with the exception of larger numbers of alveolar macrophages around terminal airways which had resolved by 3 months. Brass particulate matter was not found in the lavage fluid or in histopathological examinations. The 4 hour exposure period conforms with acute inhalation toxicity guidelines. The use of only one sex of animals and the dose levels were adequately justified. Concentrations were analytically verified and sufficient numbers of animals were used. The results from lung function measurements were not provided in the publication and the highest dose was not intended to allow estimation of the LC50. Therefore, the LC50 is greater than 888 mg/m³.

 

Based on the available data, it is proposed that aluminium oxide need not be classified for acute inhalation toxicity.

Justification for classification or non-classification

According to DSD (67/548/EEC) or CLP (1272/2008/EC) classification criteria for acute toxicity, no classification is warranted.