Dodecaaluminium trimolybdenum dodecaoxide

Endpoint summary

Description of key information

Oral (OECD 423), rat: LD50 = 5000 mg/kg bw (cut-off value)
Dermal (OECD 402), rat: LD50 > 2000 mg/kg bw (limit test)
Read across with molybdenum compounds:
Inhalation (OECD 403 ), rat: LC50 > 5 mg/L
Read across with fumed alumina:
Inhalation (OECD 403 ), rat: LC50 > 2.3 mg/L

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

The acute oral toxicity study has been performed according to OECD 423 (Colas, 2011). Two groups of 3 female rats each received a single oral dose of 2000 mg/kg bw aluminium molybdenum oxide. No mortality occurred during the 14-day observation period and no clinical signs of toxicity were observed. Body weight and body weight gain was within the normal range and no abnormalities were detected during necropsy. Therefore, the LD50 cut-off was determined to be 5000 mg/kg bw aluminium molybdenum oxide according to OECD 423.

The acute dermal toxicity study has been performed according to OECD 402 (Colas, 2011). 5 rats per sex were treated dermally with a dose of 2000 mg/kg bw aluminium molybdenum oxide under semi-occlusive conditions for 24 h. Parrafin oil was used as vehicle. In a control study, 10 rats were treated with vehicle only under the same conditions. No mortality occurred during the 14-day observation period and no clinical signs of toxicity were observed. Body weight and body weight gain was within the normal range and no abnormalities were detected during necropsy. Therefore, the LD50 was determined to be > 2000 mg/kg bw aluminium molybdenum oxide.

There are no data available on acute inhalation toxicity for aluminium molybdenum oxide. However, there are reliable data for aluminium and molybdenum compounds considered suitable for read-across using the analogue approach. For identifying hazardous properties of aluminium molybdenum oxide concerning human health effects, the existing forms of the target substance at very acidic and physiological pH conditions are relevant for the risk assessment. As aluminium molybdenum oxide is an inorganic metallic compound, the tendency to hydrolyze is based on its solubility which is highly pH-dependent. At the physiological pH of 7.4, the availability of aluminium is decreased due to the formation of insoluble Al(OH)₃; molybdenum species exist as molybdate anion (MoO₄^2-). At acidic pH conditions (pH < 4), aluminium is predominantly present as Al³⁺, whereas molybdenum species are primarily available in the acidic forms HMoO₄^-or H₂MoO₄. Since the release of aluminium and molybdate species is affected by the biological and pH conditions, the use of data on soluble aluminium and molybdenum compounds is justified for toxicological endpoints representing a worst case scenario. For further details, please refer to the analogue justification attached in section 13 of the technical dossier.

Molybdenum substances

In acute inhalation toxicity studies covering the soluble molybdenum substances disodium molybdate, diammonium dimolybdate, molybdenum trioxide, there was a complete absence of mortalities in all studies carried out according to OECD 403 (Leuschner, 2010; Jackson et al., 1991). Correspondingly, the LC50 (4h) for all tested substances was either above the maximum attainable test concentration or above the limit test concentration (> 5 mg/L air).

Aluminium compounds

The study by Cabott (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 2.58 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. 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. 

 

No data are available on the acute inhalation toxicity of aluminium molybdenum oxide. However, since aluminium molybdenum oxide is only imported as already included into the matrix and the matrix particles are greater than 100 µm, a risk potential is not expected at all. Please refer also to section 4.5.

Justification for classification or non-classification

The available data on the acute oral and dermal toxicity of aluminium molybdenum oxide do not meet the criteria for classification according to Regulation (EC) 1272/2008 (CLP) or Directive 67/548/EEC (DSD), and are therefore conclusive but not sufficient for classification.

Based on the read-across within an analogue approach, the available data on acute inhalation toxcity do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.