Titanium tetrachloride

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no data available: testing technically not feasible

Marine water

Hazard assessment conclusion:

no data available: testing technically not feasible

STP

Hazard assessment conclusion:

no data available: testing technically not feasible

Sediment (freshwater)

Hazard assessment conclusion:

no data available: testing technically not feasible

Sediment (marine water)

Hazard assessment conclusion:

no data available: testing technically not feasible

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no data available: testing technically not feasible

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Titanium tetrachloride effects were assessed on the basis on its hydrolysis products as they are formed quickly in all relevant environmental media. During hydrolysis a bimolar quantity of hydrochloric acid is formed and thus pH effects may occur. But this is not regarded as true toxicity and is excluded from assessment, which is in accordance with the endpoint related test protocols. Solely the guidance on activated sludge respiration inhibition testing (OECD TGD 209) does not exclude the observation without pH adjustment. Thus read across to hydrochloric acid and to the other transformation product, titanium dioxide was made in order to assess the potential effects to activated sludge caused by pH. As pH effects are more than three orders of magnitude higher than the one of the other transformation product it was concluded that acidity dominates rather than modifies the combined effect. Accordingly the assessment bases on read across from titanium dioxide.

The titanium dioxide formed during hydrolysis is eventually present in the rutile modification (Fisk et al 2010), which is insoluble in water (< 1 µg/L). In order to assess effects of the formed microdisperse particles the experiments with this test item used generally Water Accommodated Fractions (WAFs) together with the insoluble material in excess. This bears the risk of test artifacts due to fouling. On the other hand titanium dioxide is photocatalytically active and exposure to the undissolved test item was intentionally made for catching such effects. According to the CRC Handbook of Chemistry and Physics (2007, Lide DR Ed, CRC Press) the relative density of titanium dioxide is about 4 (anatase = 3.9, brookite = 4.17, rutile = 4.26). In consequence fast sedimentation was observed in experiments except if the aqueous medium was stirred, moved by a large number of test animals and/ or a vertical flow was maintained, e.g. by aeration. It is noteworthy that separation of the pelagic test organisms is likely to occur in the environment, particularly with regard to algae due to the large difference in density (density of algae = about 1). Photocatalytic toxicity is reported in the literature and was observable after artificial experimental exposure of algae (Hund-Rinke & Simon 2006), where separation due to the difference of the sink rates was hampered. This does not reflect a relevant environmental scenario. Photocatalytic toxicity in crystalline particles was absent at 100 nm diameter and present only at 25 nm. However it can not be fully excluded that titanium dioxide particles of relevant size may be formed in the environment it is assessed that they sink quickly and get bound firmly to sediment or suspended matter particles as evidenced by the high Koc reported from environmental samples (Roychoudhury & Starke 2006, Veselý et al 2001). Thus photocatalytic toxicity is considered not a relevant mode of action for the environmental risk assessment of the titanium tetrachloride transformation products.

 

Conclusion on classification

Albeit testing of titanium tetrachloride self is technically not feasible due to its hydrolytical instability the hazard assessment could be accomplished on the basis of read across to the transformation products. The relevant transformation product for the effects on algae, daphnids or crustacea, and fish is titanium dioxide in the rutil modification. As evidenced experimentally by studies conform to guidelines titanium dioxide is

not acute toxic

to algae, daphnids and fish in so far as no 50% effect level is reached up to the water solubility level, which was determined according to OECD Environmental Health and Safety Publications Series on testing and assessment no. 29 (Guidance document on transformation/dissolution of metals and metal compounds in aqueous media). Brouwers (2009) found the solubility below the level of detection of the analytical method, i.e. < 1 µg/L at pH 6, 7, and 8.

DSD

In accordance with the Commission Directive 2001/59/EC of 6 August 2001, chapter 5.2.1.1, p. L 225/293, titanium tetrachloride was checked on the basis of titanium dioxide effects for the applicability of R53: “May cause long-term adverse effects in the aquatic environment”, where the criteria are: “Substances not falling under the criteria listed above in this chapter, but which, on the basis of the available evidence concerning their persistence, potential to accumulate, and predicted or observed environmental fate and behaviour may nevertheless present a long-term and/or delayed danger to the structure and/or functioning of aquatic ecosystems”

The water solubility of titanium dioxide is below than 1 mg/L. Readily biodegradability and the log Kow are not applicable but the BCF is > 100 however the BCF concept may be considered not applicable as well. Nonetheless additional scientific evidence concerning the absence of toxicity at the solubility limit is proven in prolonged studies to daphnia and fish. This is considered sufficient to provide an adequate assurance that neither the substance nor its degradation products will constitute a potential long-term and/or delayed danger to the aquatic environment.

Thus according to EU standards titanium tetrachloride shall be not classified as “dangerous for the environment” and

no risk phrase applies.

CLP/GHS

In accordance with the Guidance to Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of substances and mixtures of 14 May 2009 (IHCP, DG Joint Research Centre, European Commission), Table 4.1.0, p. 427, titanium tetrachloride was checked on the basis of titanium dioxide effects for the applicability “Chronic category 4”.

According to Note 3 “no acute toxicity” is assigned because “the L(E)C50s are above the water solubility.” No evidence for potential biomagnification exists as the aquatic BCFs for all tested fish tissues is lower than 500 and since the NOECs for chronic toxicity to algae, daphnia and fish > the solubility limit and > 1 mg/L.

Thus according to Regulation (EC) no 1272/2008 of the European parliament and of the council of 16 December 2008 on classification, Labelling and packaging of substances, p. L 353/139,

no classification applies.

[1] IHCP, DG Joint Research Centre, European Commission

[2] Brouwers T (2009). 24h screening transformation/dissolution test of Chloride reactor discharge at a 100 mg/L loading in a standard aqueous medium at pH 6, 7 and 8. testing laboratory: ECTX consult bvba, Bergstraat 73, B3500 Hasselt/ analytical phase: Servaco nv, tramstraat 2, B8560 wevelgem. Owner company: TDMA (titanium dioxide manufacturers association). Study no. X09-01-014).