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Endpoint summary

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:

- Toxicity to freshwater organisms

Acute freshwater data:

For fish, 47 individual reliable acute toxicity data points for two different species were put forward for hazard assessment purposes. The acute toxicity values (96h-LC50) for Pimephales promelas varied between of 40.8 µg dissolved Pb/L (at pH 5.67 and hardness of 15.9 mg/L) and 3597.9 µg dissolved Pb/L (at pH 7.1 and hardness of 26 mg/L).The acute toxicity values (96h-LC50) for Oncorhynchus mykiss varied between of 107.0 µg dissolved Pb/L (at pH 8.8 and hardness of 290 mg/L) and 1170.0 µg dissolved Pb/L (at pH 6.9 and hardness of 32 mg/L).

For invertebrates, 43 individual reliable acute toxicity data points for two different species were put forward for hazard assessment purposes. The acute toxicity values (48h-LC50) for Ceriodaphnia dubia varied between of 26.4 µg dissolved Pb/L (at pH 8.1 and hardness of 25 mg/L) and 3115.8 µg dissolved Pb/L (at pH 8.15 and hardness of 103.2 mg/L).The acute toxicity values (48h-LC50) for Daphnia magna varied between of 107.0 µg dissolved Pb/L (at pH 8.3 and hardness of 152 mg/L) and 108.8 µg dissolved Pb/L (at pH 7.6 and hardness of 54 mg/L).

For algae, 7 individual reliable acute toxicity data points for one species were put forward for hazard assessment purposes. The acute toxicity values (48h-LC50) for Pseudokirchneriella subcapitata varied between of 21.7 µg dissolved Pb/L (at pH 7.5 and hardness of 24.2 mg/L) and 322.9 µg dissolved Pb/L (at pH 7.3 and hardness of 174.4 mg/L).

Chronic freshwater data:

A Species Sensitivity Distribution (SSD) has been developed for the assessment of lead in the freshwater compartment, using the reliable species-specific chronic toxicity effect levels that have been identified in the previous section of this report. In total, 98 individual high quality NOEC/L(E)C10 values and 18 different species NOEC/L(E)C10 values were compiled from the database. Chronic NOEC/L(E)C10 values are available for 1 unicellular algal species (Pseudokirchneriella subcapitata), 1 higher plant (Lemna minor), 2 rotifer species (Philodina rapida; Brachionus calyciflorus), 1 insect (Chironomus tentans), 2 mollusc species (Lymnaea palustris; Lymnaea stagnalis), 5 crustacean species (Hyalella azteca, Daphnia magna, Ceriodaphnia dubia, Diaphanosoma birgei, Alona rectangula) and 6 fish species (Oncorhynchus mykiss, Salvelinus fontinalis, Pimephales promelas, Lepomis macrochirus, Salvelinus namaycush, Ictalurus punctatus, Salmo salar). No-effect levels for dissolved lead for fish were situated between 18.9 µg Pb/L (Oncorhynchus mykiss; endpoint: scoliosis) and 1558.6 µg Pb/L (Pimephales promelas; endpoint: dry weight). No-effect levels for dissolved lead for invertebrates were situated between 1.7 µg Pb/L (Lymnaea stagnalis; endpoint: growth) and 495.7 µg Pb/L (Ceriodaphnia dubia; endpoint: mortality). No-effect levels for dissolved lead for algae/higher plants were situated between 29.5 µg Pb/L (Lemna minor; endpoint: root length) and 1558.6 µg Pb/L (Lemna minor; endpoint: root length).

All high quality chronic data retained for PNEC derivation were normalised for bioavailability. Indeed, reports/publications reporting toxicity data as total Pb concenrations were in first instance converted to dissolved Pb concentrations using the equation generated by Blust (2010). An additional step in the bioavailability correction was introduced to normalize the chronic freshwater toxicity data towards the dissolved organic carbon (DOC) using the Minteq 2.61 software.

As mentioned before, the normalised Pb toxicity data have been used for the construction of a Species Sensitivity Distribution (SSD) from which the median 5th percentile, i. e. the HC5-50 with 5%-95%-confidence interval, has been derived. Using the software package BestFit, a Log-Uniform Distribution was defined as the best fitting distribution. The HC5-50 for dissolved Pb associated with the reasonable worst case DOC concentrations of 2.6 mg/L was 19.6 µg/L for dissolved lead.

Application of an assessment factor between 1 and 5 on this HC5-50 will result in the final PNEC for lead in the freshwater environment. Based on the available data, the following points have to be considered when determining the size of the assessment factor:

- The chronic Pb database covers only ecologically relevant endpoints. The selected endpoints were mortality, growth, hatching, reproduction and abnormalities,

- The NOEC/L(E)C10 data were extracted from tests performed in a variety of natural/artificial freshwaters, covering a considerable part of the wide range of the freshwater characteristics (pH value and hardness) that are normally found in European freshwaters.

- The chronic Pb database covers sensitive life stages and ‘chronic’ exposure times for all trophic levels.

- The eight different trophic levels that were defined in the London workshop (2001) are represented in the database

- From the extracted data, it seems that the Pb database do fulfill the requirement of 10-15 different NOEC values from the London Workshop. Indeed, 98 individual high quality NOEC/EC10 values and 18 different species NOEC values (fish, invertebrates and algae) were compiled from the database.

- The use of the best fitting Uniform distribution minimizes the statistical uncertainties around the HC5-50 value.

- Comparison between field and mesocosm studies and the HC5-50 suggest that the HC5 -50 is sufficiently protective. However, only a limited number of data are available.

- The high sensitivity of Lymnaea sp. is not expected as the occurrence of Lymnaea sp. in European freshwaters is very common. Therefore it has been decided not to retain the low NOEC value of 1.7 µg dissolved Pb/L in the database for PNEC derivation.

However in conclusion on the subject on the choice of the assessment factor and considering all arguments above including the particular cautious approach taken for derivation of HC5-50 it is felt that the most appropriate AF would be 3. Therefore, hence the reasonable worst case freshwater PNEC is proposed to be 6.5 µg dissolved Pb/L, which will be carried over to the risk characterization.

- Toxicity to marine organisms

A Species Sensitivity Distribution (SSD) has been developed for the assessment of lead in the marine compartment, using the reliable species-specific chronic toxicity effect levels that have been identified in the previous section of this report. In total, 24 individual high quality NOEC/L(E)C10 values and 9 different species NOEC/L(E)C10 values were compiled from the database. Chronic NOEC/L(E)C10 values are available for 2 unicellular algal species (Skeletonema costatum, Dunaliella tertiolecta), 2 echinoderms (Strongylocentrotus purpuratus, Dendraster excentricus), 3 bivalve molluscs (Mytilus galloprovincialis, Mytilus trossolus, Crassostrea gigas), 1 annelid (Neanthes arenaceodentata) and 1 fish (Cyprinodon variegatus). The selected no-effect levels for dissolved lead for fish was 229.6 µg Pb/L (Cyprinodon variegatus; endpoint: dry weight. No-effect levels for dissolved lead for invertebrates were situated between 9.2 µg Pb/L (Mytilus trossolus; endpoint: abnormalities) and 1409.6 µg Pb/L (Mytilus galloprovincialis; endpoint: mortality). No-effect levels for dissolved lead for algae/higher plants were situated between 52.9 µg Pb/L (Skeletonema costatum; endpoint: yield) and 1231.8 µg Pb/L (Dunaliella tertiolecta; endpoint: growth rate).

As mentioned before, the high quality dissolved Pb toxicity data have been used for the construction of a Species Sensitivity Distribution (SSD) from which the median 5th percentile, i. e. the HC5-50 with 5%-95%-confidence interval, has been derived. Using the software package BestFit, a Log-Normal Distribution was defined as the best fitting distribution. The HC5-50 for dissolved Pb was 10.2 µg/L.

Application of an assessment factor between 1 and 5 on this HC5-50 will result in the final PNEC for lead in the marine environment. Based on the available data, the following points have to be considered when determining the size of the assessment factor:

- The chronic Pb database covers only ecologically relevant endpoints. The selected endpoints were mortality, growth, emergence, reproduction and abnormalities,

- The NOEC/L(E)C10 data were extracted from tests performed in a variety of natural/artificial marine waters, covering a considerable part of the wide range of the marine water characteristics (pH value and salinity) that are normally found in European coastal waters.

- The chronic Pb database covers sensitive life stages and ‘chronic’ exposure times for all trophic levels.

- The eight different trophic levels that were defined in the London workshop (2001) are represented in the database

- The database includes a broad representation of temperate marine organisms, including unicellular algae, invertebrates, and fish. However, no crustaceans are included in the database. Indeed, 24 individual high quality NOEC/EC10 values and 9 different species NOEC values were compiled from the database.

- All tests were performed in artificial test media which are considered to promote metal bioavailability (i. e., worst-case conditions) due to the absence of natural compounds in the water that can form metal complexes and, hence, reduce metal bioavailability and toxicity (e. g., dissolved organic matter);

- The use of the best fitting Log-Normal distribution minimizes the statistical uncertainties around the HC5-50 value.

- No data allowed the comparison between field and mesocosm studies and the HC5-50.

However in conclusion on the subject on the choice of the assessment factor and considering all arguments above including the particular cautious approach taken for derivation of HC5-50 it is felt that the most appropriate AF would be 3. Therefore, hence the reasonable worst case marine PNEC is proposed to be 3.4 µg dissolved Pb/L, which will be carried over to the risk characterization.

- Toxicity to micro-organisms in sewage treatment systems

The bacterial studies including single-species tests and mixed-population tests (e.g. activated sludge, respiration inhibition tests), resulted in toxicity values for microbial degradation in STP, e.g. sludge with inhibition of respiration and nitrification as endpoints, ranging from 1.06 mg/L to 9.59 mg/L Pb.The protozoan tests resulted in L(E)C50 values ranging from <1.5 mg/L (LC50 for different ciliate species) to >250 mg/L (LC50 for Tetrahymena pyriformis).

The lowest observed NOEC value for inhibition of nitrification using activated sludge was 2.79 mg/L dissolved Pb. The lowest observed NOEC value for inhibition of respiration was 1.06 mg/L dissolved Pb. The lowest observed bounded EC50 value from tests with other ciliated protozoa tested in activated sludge mixed liquor medium is 2.29 mg Pb/L (for ciliate Vorticella convallaria). On the other hand, a (visually) derived LC10 for the sludge protozoan community in the activated sludge mixed liquor of 1 mg/L dissolved Pb is estimated. Preference was given to this community endpoint because it is more relevant.

Based on the above reported results and discussion at TCNES II 07 a preference was expressed for application of an assessment factor of 10. In this case, a PNEC for micro-organisms of 0.1 mg/L for dissolved lead in effluent is calculated and, at the request of TCNES, this is the value forwarded to risk characterisation. Note that there are insufficient useful data for aquatic micro-organisms to apply statistical extrapolation.

- Toxicity to freshwater sediment organisms

Toxicity data for Pb to sediment organisms are summarized in the voluntary risk assessment of lead (LDAI, 2008). For lead a complete set of freshwater sediment effects data is available for the sediment compartment with 7 NOEC values for 7 different species (Tubifex tubifex, Ephoron virgo, Hyalella azteca, Gammarus pulex, Lumbriculus variegatus, Hexagenia limbata and Chironomus tentans). The chronic no-effect toxicity values for the freshwater sediment-dwelling organisms varied between 577 and 3390 mg/kg dw.

Therefore, similar to what has been agreed for the nickel and copper risk assessments it is appropriate to evaluate the benefits of estimating the PNEC for sediment by using the available toxicity sediment toxicity tests and applying the statistical extrapolation methodology, the median fifth percentile (HC5 -50) of the best fitting species sensitivity distribution has been calculated. Using the software package ETx, the Log-Normal Distribution was selected. The HC5-50 for total Pb in freshwater sediment was 522 mg/kg dw.

Application of an assessment factor between 1 and 5 on this HC5-50 will result in the final PNEC for lead in the freshwater sediment. Based on the available data, the following points have to be considered when determining the size of the assessment factor:

- The chronic Pb database covers only ecologically relevant endpoints. The selected endpoints were mortality, growth, emergence, reproduction and biomass,

- The chronic Pb database covers sensitive life stages and ‘chronic’ exposure times for all trophic levels.

- High quality chronic L(E)C10/NOEC values are available for 7 different sediment-dwelling invertebrates, belonging to 3 different families (i.e. oligochaetes, crustaceans and insects) with different feeding habits and ecological niches,

- The use of the best fitting Log-Normal distribution minimizes the statistical uncertainties around the HC5-50 value.

- No data allowed the comparison between field and mesocosm studies and the HC5-50.

However in conclusion on the subject on the choice of the assessment factor and considering all arguments above including the particular cautious approach taken for derivation of HC5-50 it is felt that the most appropriate AF would be 3. Therefore, hence afreshwater sediment PNECis proposed to be174 mg Pb/kg dw, which will be carried over to the risk characterization.

In addition, a freshwater sediment PNEC corrected for bioavailability has been calculated. Since AVS is a determining factor in controlling lead toxicity in sediments a bioavailable PNEC (corrected for AVS) has also been derived. In the VRAR of lead (2008) the statistical distribution method has been used to derive a PNEC bioavailable of 81 mg/kg dry wt. However, since some datapoints included in the SSD were derived from actual LOEC values SCHER recommended the use of the classical AF factor approach applying a factor of 10 to the lowest unbounded bioavailable NOEC. In this case the lowest NOEC was 2.0 µmol excess Pb/g dw, resulting in abioavailable freshwater sediment PNECof 0.2 µmol excess Pb/g dry wt or41 mg Pb/kg dw

- Toxicity to marine sediment organisms

EC10/NOEC values (total Pb) for lead are available for two marine sediment-dwelling organisms. These NOEC/L(E)C10 values cover different habitats and feeding behaviors and varied between 680 and 1281 mg/kg dw.To calculate the PNEC for the marine sediment compartment, the long term marine and freshwater sediments effect data are pooled in a common dataset resulting in 9 EC10/NOEC values for 9 different sediment-dwelling species. Therefore the PNEC for marine sediment was estimated by using the available freshwater and marine toxicity sediment toxicity tests and applying the statistical extrapolation methodology.

Using the software package ETx, the Log-Normal Distribution was selected. The HC5-50 for total Pb in marine sediment was 492.5 mg/kg dw.

Application of an assessment factor between 1 and 5 on this HC5-50 will result in the final PNEC for lead in the marine sediment. Based on the available data, the following points have to be considered when determining the size of the assessment factor:

- The pooled chronic Pb database covers only ecologically relevant endpoints. The selected endpoints were mortality, growth, emergence, reproduction and biomass,

- The chronic Pb database covers sensitive life stages and ‘chronic’ exposure times for all trophic levels.

- High quality chronic L(E)C10/NOEC values are available for 9 different sediment-dwelling invertebrates, belonging to 3 different families (i.e. oligochaetes, crustaceans and insects) with different feeding habits and ecological niches,

- The use of the best fitting Log-Normal distribution minimizes the statistical uncertainties around the HC5-50 value.

- No data allowed the comparison between field and mesocosm studies and the HC5-50.

However in conclusion on the subject on the choice of the assessment factor and considering all arguments above including the particular cautious approach taken for derivation of HC5-50 it is felt that the most appropriate AF would be 3. Therefore, hence amarine sediment PNECis proposed to be164.2 mg Pb/kg dw, which will be carried over to the risk characterization.