Diiron titanium pentaoxide

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Description of key information

In accordance with REACH Annex XI, section 1 the study does not need to be conducted as the substance is highly insoluble in water and unlikely to cross biological membranes, hence indicating that aquatic toxicity is unlikely to occur. This conclusion is supported by assessments for the structural analogues diiron trioxide (CAS 1309-37-1) and titanium dioxide (CAS 13463-67-7) demonstrating that long-term toxicity to fish is not to be expected. Therefore, generating additional data is scientifically not justified.

Additional information

Non-submission justification

No data on long-term toxicity of diiron titanium pentaoxide to fish are available. Generating new data is considered scientifically unjustified because of the following: diiron titanium pentaoxide was assessed in three guideline studies to be sparingly soluble in water (references 4.8-2,  4.8-3 and 4.8-1). In a worst case approach the water solubility of the test item was determined to be 2.715 µg/L at a temperature of 20 °C (please refer to the endpoint summary in IUCLID section 4.8). The substance is inorganic and a partition coefficient octanol/water (log Kow) did thus not need to be derived (please see IUCLID section 4.7). Furthermore, the maximum of the mono-modal particle size distribution was observed at approximately between 10 µm and 20 µm. The D10, D50 and D90 percentile were determined as L10 = 7.07 µm, L50 = 13.1 µm and L90 = 22.9 µm, respectively. Considering these physicochemical properties, diiron titanium pentaoxide is unlikely to cross biological membranes (please also refer to IUCLID section 7.1). Therefore, this endpoint was waived in compliance with Annex XI, section 1 to Regulation (EC) No 1907/2006 (REACH).

Nevertheless, information available for the read across source substances titanium dioxide (CAS 13463-67-7) and diiron trioxide (CAS 1309-37-1) is summarized below.

Key information on long-term toxicity to fish provided in public ECHA REACH dossiers for the read across substances titanium dioxide and diiron trioxide

Titanium dioxide

According to the public ECHA REACH dossier for the read across substance titanium dioxide (last accessed on: 18 March 2020) several studies on toxicity to early life-stages of different fish species demonstrated that dispersed microsized titanium dioxide is not chronically toxic to freshwater fish up to at least 500 mg/L (NOEC ≥ 500- 1000 mg/L). For dispersed nanosized titanium dioxide a NOEC of ≥ 100 - < 1000 mg/L was derived. Taking into account its low water-solubility, microsized titanium dioxide is not considered to be chronically toxic up to its solubility limit.

Likewise titanium dioxide was assessed to be not acutely toxic to fish (please refer to IUCLID section 6.1.1).

Diiron trioxide

In the public ECHA REACH dossier for the read across substance diiron trioxide (last accessed on: 18 March 2020) it is concluded that in accordance with section 1 of REACH Annex XI, the study on long-term toxicity to fish is scientifically not necessary since the natural baseline iron concentrations in the aquatic environment are much higher than the saturation concentrations of iron oxides reported for the environment. It would thus be unlikely that iron ions released from iron oxides are toxic to fish.

Additionally, diirion trioxide was not found to be acutely toxic to fish (please refer to endpoint summary in IUCLID section 6.1.1).  

Conclusion

Based on the physicochemical properties of diiron(III) titanium pentaoxide and its uses, a test on long-term toxicity to fish is scientifically not justified. Moreover, the source substances titanium dioxide (CAS 13463-67-7) and diiron trioxide (CAS 1309-37-1) are found to be non-toxic to fish both in short-term and long-term. Both structural analogues are neither classified for short-term (acute) nor long-term (chronic) aquatic toxicity according to Regulation (EC) No 1272/2008 (CLP).

Target and source substances are metal-containing inorganic oxides. The target substance diiron titanium pentaoxide is a mixed oxide of titanium dioxide and diiron trioxide. The source substances share the common atoms Ti, O and Fe with the target substance and have very similar physico-chemical properties. Therefore, based on an analogue approach, diiron titanium pentaoxide is also not considered chronically toxic to fish. Additional data on long-term toxicity of diiron titanium pentaoxide to fish are thus scientifically not necessary.