Dialuminium zinc tetraoxide

Endpoint summary

Description of key information

Oral, rat: LD50 cut-off value: unclassified (Colas, 2011a)
Inhalation, rat: WoE LC50: > 5 mg/m³ (RA CAS 1314-13-2, maximal attainable concentration under experimental conditions)
Dermal, rat: LD50: > 2000 mg/kg bw (Colas, 2011b)

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Sep - 05 Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

GLP compliance:

yes (incl. QA statement)

Remarks:

GROUPE INTERMINISTERIEL DES PRODUITS CHIMIQUES

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

other: Sprague Dawley (SPF Caw)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Elevage JANVIER, Le Genest St Isle, France
- Age at study initiation: 8 weeks
- Weight at study initiation: 178 - 208 g
- Fasting period before study: animals were fasted one day prior to substance administration until 4 hrs after substance administration (diet only).
- Housing: 3 animals per cage in solid-bottomed clear polycarbonate cages with stainless steel mesh lids
- Diet: M20 (pelleted), Specific Diet Services, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25
- Humidity (%): 30 - 70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

oral: gavage

Vehicle:

DMSO

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 200 mg/mL
- Amount of vehicle (if gavage): 10 mL/kg bw


MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg bw

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

3 (controls), 6 (test substance group; 3 animals per step in a two-step testing procedure)

Control animals:

other: as control group, 3 animals received 10 mL/kg bw DMSO via gavage in an additional study performed from 28 Jun - 12 Jul 2011.

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: animals were observed 0.5, 1, 3 and 4 h after substance administration and daily thereafter and individual body weights were determined periodically on day 0 (prior to substance administration), 2, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, other: macroscopical examination of oesophagus, stomach, duodenum, jejunum, ileon, caecum, colon, rectum, spleen, liver, thymus, trachea, lungs, heart, kidneys, urinary bladder, ovaries, uterus, adrenals and pancreas

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occured during the study period.

Clinical signs:

other: No clinical signs of toxicity were observed up to the end of the 14-day observation period.

Gross pathology:

Macroscopical examinations revealed no substance-related findings.

Interpretation of results:

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

Conclusions:

CLP: not classified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate and reliable study (Klimisch score 1), 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

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from reference substances. Read-across is based on the basic assumption that the ionic species of the target substance are not released at physiological pH due to the insolubilty of the test substance. The selected studies are thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.5, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Sep - 04 Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

GLP compliance:

yes (incl. QA statement)

Remarks:

GROUPE INTERMINISTERIEL DES PRODUITS CHIMIQUES

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

other: Sprague Dawley (SPF Caw)

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source: Elevage JANVIER, Le Genest St Isle, France
- Age at study initiation: 7 and 8 weeks for male and female rats, respectively
- Weight at study initiation: 229 - 255 g (males), 194 - 229 g (females)
- Housing: individual during treatment, 5 animals per cage thereafter in solid-bottomed clear polycarbonate cages with stainless steel mesh lids
- Diet: M20 (pelleted), Specific Diet Services, ad libitum
- Water: tap water, ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25
- Humidity (%): 30 - 70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 / 12

Type of coverage:

other: porous gauze dressing

Vehicle:

DMSO

Details on dermal exposure:

TEST SITE
- Area of exposure: clipped skin of the dorsal area of the trunk
- % coverage: 10%

REMOVAL OF TEST SUBSTANCE
- Washing: residual test material was removed with distilled water
- Time after start of exposure: 24 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 mL/kg bw
- Concentration (if solution): 200 mg/mL
- Constant volume or concentration used: yes


VEHICLE
- Amount(s) applied (volume or weight with unit): 10 mL/kg bw

Duration of exposure:

24 h

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

other: as control group, 5 male and female animals received 10 mL/kg bw DMSO by topical administration in an additional study performed from 28 Jun - 12 Jul 2011

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: animals were observed 1, 3 and 5 h after substance administration and daily thereafter and individual body weights were determined periodically on days 0 (prior to substance application), 2, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, other: macroscopical examination of oesophagus, stomach, duodenum, jejunum, ileon, caecum, colon, rectum, spleen, liver, thymus, trachea, lungs, heart, kidneys, urinary bladder, testicles, treatment area, adrenals and pancreas

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occured during the study period.

Clinical signs:

other: No clinical signs of toxicity were observed up to the end of the 14-day observation period. Erythema were noted on the treated areas of all test animals 24 h after substance application and they were totally reversible on day 2.

Gross pathology:

Macroscopical examinations revealed no substance-related findings.

Interpretation of results:

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

Conclusions:

CLP: not classified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate and reliable study (Klimisch score 1), and is thus sufficient to fulfil the standard information requirements set out in Annex VII, 8.5, of Regulation (EC) No 1907/2006.

Additional information

Acute toxicity

Justification for read-across

There are no data available on acute toxicity of Zinc aluminium oxide following inhalation. In accordance with Regulation (EC) No 1907/2006, Annex XI, 1.5 read-across from appropriate substances is conducted to fulfill the standard information requirements set out in Regulation (EC) No 1907/2006, Annex VII, 8.5.

According to Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met”. In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across) “to avoid the need to test every substance for every endpoint”.

Zinc aluminium oxide is an inorganic metal composed of zinc oxide and aluminium oxide [ZnO*[Al2O3)8-9), which is insoluble in water. Therefore, it is probable to assume that the target substance has a low degree of solubility at the physiological pH of 7.4. Considering that toxicity of solids/dusts and aerosols of insoluble substances following inhalation is attributed not only to intrinsic properties of the test substance but also to physical properties of particles, reliable data on the insoluble read-across source substances zinc oxide (CAS 1314-13-2) and aluminium oxide (CAS 1344-28-1) were considered to evaluate hazardous properties of the insoluble target substance zinc aluminium oxide by inhalation.

Acute toxicity: oral

The acute toxicity of Zinc aluminium oxide was determined in a recent GLP-Guideline study according to the acute toxic class method (OECD 423) in which two groups of Sprague Dawley rats were exposed to 2000 mg Zinc aluminium oxide/kg bw in a single oral application of 10 mL/kg bw via gavage (Colas, S. 2011a). No mortality occurred during the study and no alterations in clinical signs or on body weight gain were determined until the end of the study period. Further, pathological examinations did not reveal any specific findings.In conclusion, the LD50 cut-off value of Zinc aluminium oxide after oral exposure is unclassified.

Acute toxicity: inhalation

Zinc compounds:

Only limited data on acute toxicity following inhalation of zinc oxide are available. One study describes the effects of zinc oxide following inhalation in rats with special emphasis on cellular and biochemical changes in the broncho-alveolar lavage fluid (Gordon et al., 1992). Male Fischer 344 rats were exposed to aerosols with 2.5 or 5µg zinc oxide/L for 3 h in a nose-only exposure chamber. Following this exposure, animals were anesthetized and pulmonary lavage samples were prepared and analysed for biochemical and cellular parameters including protein content, lactate dehydrogenase (LDH), β-glucuronidase level and cell counts. In addition, lung burden levels of Zn were determined in animals exposed to 4.3 µg/L test material for 3 h. No mortality was reported. Dose-dependent, significant increases in total cell counts, protein content, LDH and β-glucuronidase occurred which indicates induction of inflammation under the conditions of the test. Similar results were observed in guinea pigs whereas no effects were reported in rabbits. Moreover, no significant effects on lung function were observed in humans (Gordon et al., 1992 (as cited in US EPA, 2005)). Zinc retention in lungs was found to be 11.5 %. Interpretation of the data in regard to risk assessment is difficult as it remains unclear if the inflammation in the lungs was caused by substance-specific effects due to intrinsic properties of zinc oxide or to a general effect based on deposition of particles in the lung. However, considering a general occupational limit concentration of 3 mg/m³ for dusts reaching the alveolar region (TRGS 900), no hazard under normal conditions of use is considered for zinc oxide as the determined effect level exceeded this limit concentration.

Aluminium compounds:

Two acute inhalation studies are available on aluminium oxide (Hazleton Laboratories, 1969; Cerven, 1996). First, toxicity of aluminium oxide was tested after acute inhalation in a study performed similar to OECD guideline 403 with the deviation that exposure duration accounted 1 instead of 4 hours (Hazleton Laboratories, 1069). 10 male Charles River rats were exposed to aerosols of 5.06, 5.88, 6.28 and 8.22 mg/L in a whole-body exposure system. Mortality was observed at the 3 highest dose levels either during or shortly after exposure: exposure to 5.88, 6.28 and 8.22 mg/mL resulted in mortality of 1/10, 3/10 and 5/10 test animals, respectively. Observed clinical symptoms like piloerection, brown discharge around the nose and slow/deep respiration indicated respiratory distress, which was reversible within the 14-day observation period in surviving animals. Only slight effects on body weight were reported in test animals. Gross necropsy of non-surviving animals revealed discoloration of the lungs. Moreover, a white gel formed by the test item at high humidity was detected in the stomach and trachea, which indicates suffocation due to blockage of air passages as reason for mortality. Moreover, stomachs appeared enlarged and gas-filled. Based on mortality, a LC50 of 7.6 mg/L was derived in the conducted study. Therefore, aluminium oxide is not classified as acute toxic following inhalation.

In the second study, Cerven exposed 5 male and female Wistar Albino rats to 2.3 mg/L aluminium oxide (fumed alumina) in an inhalation chamber for 4 hours (whole body) similar to OECD guideline 403 (Cerven, 1996). The average mass median diameter was 2.58 µm 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. Weight gain appeared normal in all male animals whereas 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 available data on acute toxicity following inhalation do not clearly indicate hazardous properties of the read-across substances zinc oxide and aluminium oxide. However, zinc oxide induced inflammatory reactions in the lungs which might be caused by a general, particle-induced mode of action due to deposition of particles in the lung. Considering the results of the acute toxicity studies after oral and dermal exposure, where no hazard was identified up to the limit dose, hazardous potency due to intrinsic properties of zinc aluminium oxide remains unlikely which might result in toxicity following inhalation. Furthermore, zinc aluminium oxide is not irritating to skin or eyes or sensitising, which supports the assumption that zinc aluminium oxide does not exhibit toxicity following inhalation due to local effects in the lungs. The estimated LC50 values for aluminium oxide are above the limit dose of 5 mg/mL. Therefore, zinc aluminium oxide is not expected to be hazardous after inhalation.

Acute toxicity: dermal

A GLP-conducted acute dermal toxicity study was performed according to OECD 402 (Colas, 2011b). 24 h after test substance application, erythema was observed in all test animals on the treated skin areas. Neither mortality nor clinical signs of toxicity were observed. In addition, body weight gain was not altered in test animals. Further, macroscopical examinations did not reveal any treatment-related changes. Thus, the dermal LD50 is > 2000 mg/kg bw.

In conclusion, Zinc aluminium oxide is not expected to induce acute toxicity following oral, inhalation or dermal routes.

References not included in IUCLID:

US EPA, 2005. Toxicological Review of Zinc and Compounds (EPA/635/R-05/002)

Justification for classification or non-classification

Based on the available data on acute toxicity, Zinc aluminium oxide does not meet the criteria for classification according to Regulation (EC) 1272/2008.