Lead titanium trioxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

6.5 µg/L

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

3.4 µg/L

Assessment factor:

3

Extrapolation method:

sensitivity distribution

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

174 mg/kg sediment dw

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

164 mg/kg sediment dw

Assessment factor:

3

Extrapolation method:

sensitivity distribution

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

147 mg/kg soil dw

Assessment factor:

2

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

10.9 mg/kg food

Assessment factor:

6

Additional information

In assessing the ecotoxicity of metals in the various environmental compartments (aquatic, terrestrial and sediment), it is assumed that toxicity is not controlled by the total concentration of a metal, but by the bioavailable form. For metals, this bioavailable form is generally accepted to be the free metal-ion in solution. In the absence of speciation data and as a conservative approximation, it can also be assumed that the total soluble lead pool is bioavailable. All reliable data on ecotoxicity and environmental fate and behaviour of lead and lead substances were therefore selected based on soluble Pb salts or measured (dissolved) Pb concentration.

 

The reliable ecotoxicity data selected for effects assessment of Pb in the various environmental compartments are derived from tests with soluble Pb salts (lead dinitrate and lead dichloride). Since lead is the toxic component and the anions do not contribute significantly to toxicity, all reliable data are grouped together in a read-across approach and the PNEC’s are expressed asμg Pb/L (measured dissolved concentration) or mg Pb/kg. These results can be used for all other Pb compounds without concern on toxicity of the anions.

 

When Lead titanium trioxide is exposed to water, the dissolution of the lead ion is relatively low compared to the more soluble lead salts used for testing. Based on the water solubility test lead concentrations up to 0.08 mg/l can be reached. Theoretically, this means that release of Lead titanium trioxide in fresh and marine waters may result to possible concentrations above the PNEC. However, as lead is captured within the matrix of LTO, only a very small percentage of the lead present will be available. This means that the dissolved fraction of lead is a function of much higher amounts of insoluble Lead titanium trioxide present. In other words, the predicted environmental concentration (PEC) of lead is directly related with the loading of insoluble Lead titanium trioxide. 

 

Conclusion on classification

A TDp 24 h screening test is available for Lead oxide although limited to pH8 information. Given the lower acute toxicity reference values at pH6 (79,4 µg/l) and pH7 (56,1 µg/l) and the expected higher solubility at this pH (> 100 µg/l), it can be deduced/concluded that with the information available, PbO would fail the 24h screening test and should therefore be classified as the soluble Pb ion, corrected for molecular weight, being :

· Under DSD : R50/53, with an M factor of 10

· Under CLP : Acute 1 – Chronic 1, with an M factor of 10

Given the solubility of Lead titanium trioxide at this pH (78 µg/L at 20 °C), it can be deduced/concluded that with the information available, Lead titanium trioxide can be classified as the soluble Pb ion, corrected for molecular weight, being:

· Under DSD: R50/53, with an M factor of 1

· Under CLP: Acute 1 – Chronic 1, with an M factor of 1

In line with annex 4 chapter IV.5.3 of the CLP, Metal compounds must be classified by comparing Transformation Dissolution data with toxicity date for the soluble metal ion. The availability of toxicity information on the soluble ion (developed under the Lead metal registration file) makes the requirement for aquatic ecotoxicity tests on Lead oxide redundant.

Transformation Dissolution data in accordance to the OECD protocol are available for Lead oxide but to a limited extend (24h screening test at pH 8 only). There is therefore no absolute need for further developing Transformation Dissolution data on Lead-oxide given a default classification of R50-53 or Acute 1-Chronic 1, could be derived

It is however noted that due to the default nature of this assessment that further Transformation Dissolution testing on the compound has the potential to alter the classification to a lower classification category.