Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Read-across approach for lead containing glass, oxide, chemicals:

The test item is covered under the definition "glass". In this context, “glass" is defined as an amorphous, inorganic, transparent, translucent or opaque substance formed by variouspowdery substances (mostly oxides) which are not present as such in the final glass: they are fully integrated into the glass matrix through the melting process and they lose their original characteristics. Thus, the available analytical information is only of quantitative nature without any indication as to elemental composition or structural purposes. Based on the definition under Regulation (EC) No 1907/2006, the test item fulfils the criteria for UVCB substances.

Substance-specific information for the test item glass, oxide, chemicals (water solubility < 100 mg/L) are not available. For this reason, read-across is anticipated to lead monoxide as a moderately soluble lead substance.

This read-across is considered justified and also conservative since lead monoxide (water solubility approx. 700 mg/L at 20°C) is one of the major starting materials (content ranging from approx. 30-80%) for the test item manufacture, and also represents the component of major toxicological concern.

For the substantiation of read-across, solubility tests (T/D and bioaccessibility) were performed with the test item in order to determine the release of lead from the “glass” matrix for a comparison to the solubility of the selected read-across substance.

The following lead concentrations were measured in two T/D tests with the test item with variable lead monoxide concentrations (starting material concentration):

Test material with a PbO content of 38.4%:

After 7 days, the dissolution of Pb ranged from 17.0 ± 1.99 µg/L (pH 8) to 18.7 ± 2.08 µg/L (pH 6).

After 28 days, the dissolution of Pb ranged from 37.8 ± 3.64 µg/L (pH 8) to 60.1 ± 17.2 µg/L (pH 6).

Based on the nominal test item amount, the maximum dissolution of Pb at pH 6 from the test item corresponded to 6.01% (w/w); based on contained lead 5.95% (w/w).

At pH 8, the maximum dissolution of Pb after 24 h based on contained Pb was 3.68 µg/L (1.03% (w/w)).

Test material with a PbO content of 78.0%:

After 7 days, the dissolution of Pb ranged from 53.8 ± 8.53 µg/L (pH 8) to 562 ± 86.1 µg/L (pH 6).

After 28 days, the dissolution of Pb ranged from 110 ± 8.28 µg/L (pH 8) to 684 ± 22.8 µg/L (pH 6).

At pH 6, the maximum dissolution of Pb from the test item was 68.4% (w/w) based on nominal test item loading. Based on contained Pb, the dissolution corresponded to 94.3 % (w/w).

At pH 8, the maximum dissolution of Pb after 24 h based on contained Pb was 29.4 µg/L (4.06 % (w/w)).

In comparison, a water solubility of lead monoxide (saturation solubility, OECD 105; Heintze 2005) of is given with 70.2 mg/L in the REACH registration dossier and in the "Voluntary Risk Assessment for Lead and Lead Compounds"; a T/D screening test at pH = 8 with a 100 mg/L loading revealed an average (+- SD) dissolved Pb concentration after 24 hours of 101 (+-0.003) µg/L.

Based on the above data, the release of Pb fromthe test item glass, oxide, chemicals is substantial, but eithersimilar or lower compared to pure PbO. Thus, read-across to lead monoxide can be considered scientifically justified and sufficiently conservative.

Discussion:

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 data selected for the environmental fate and behaviour of lead are all based on either monitoring data of prevailing lead concentrations in water, soil, sediment, suspended matter and organisms or on experimental resultswithlead (di)nitrate and lead chloride. All reliable data are expressed based on elemental Pb concentrations and grouped together in a read-across approach and will be used for all lead substances because upon dissolution of lead substances, the Pb-ion is the controlling adsorption and bioaccumulation.