Registration Dossier

Diss Factsheets

Administrative data

Endpoint:
toxicity to terrestrial arthropods: long-term
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
According to Column 2 of Information Requirement 9.4., Annex X, Commission Regulation (EU) 1907/2006 ”Long-term toxicity testing shall be proposed by the registrant if the results of the chemical safety assessment according to Annex I indicates the need to investigate further the effects of the substance and/or degradation products on terrestrial organisms. The choice of the appropriate test(s) depends on the outcome of the chemical safety assessment. These studies do not need to be conducted if direct and indirect exposure of the soil compartment is unlikely.”

According to Section 8.4.2 of ECHA Guidance on IR & CSA, Part B: Hazard assessment (Version 2.1; ECHA, 2011), “For substances which are classified as harmful, toxic or very toxic to aquatic life (i.e. H412, H411, H410 and H400), an aquatic PNEC can be derived. In these circumstances there are unclassified hazards to the sediment and soil compartments because toxicity to aquatic organisms is used as an indicator of concern for sediment and soil organisms, and a screening risk characterisation is undertaken using the equilibration partitioning method (EPM) to derive PNECs for sediment and soil. Hence quantitative exposure assessment, i.e. derivation of PECs, is mandatory for the water, sediment and soil environmental compartments.

Substances with the only environmental classification as ‘May cause long lasting harmful effects to aquatic life’ (i.e. H413) have been established as persistent in the aquatic environment and potentially bioaccumulative on the basis of test or other data. There are also potential hazards for these substances for the sediment and soil compartments, because these substances are potentially bioaccumulative in all organisms and are also potentially persistent in sediment and soil. Hence exposure assessment is mandatory for the water, sediment and soil environmental compartments, which may be quantitative or qualitative as appropriate. PBT and vPvB substances have been established as persistent and bioaccumulative (and the former also as toxic) in the environment as a whole. Hence qualitative exposure assessment is mandatory for the water, sediment and soil environmental compartments…

If there are ecotoxicity data showing effects in aquatic organisms, but the substance is not classified as dangerous for the aquatic environment, an aquatic PNEC can nevertheless be derived thus indicating a hazard to the aquatic environment. In these circumstances there are also unclassified hazards to the sediment and soil compartments because toxicity to aquatic organisms is used as an indicator of concern for sediment and soil organisms and a screening risk characterisation is undertaken using the equilibration partitioning method (EPM) to derive PNECs for sediment and soil. Hence quantitative exposure assessment, i.e. derivation of PECs, is mandatory for the water, sediment and soil environmental compartments.”

Zirconium praseodymium yellow zircon can be considered environmentally and biologically inert due to the characteristics of the synthetic process (calcination at a high temperature of approximately 1000°C), rendering the substance to be of a unique, stable crystalline structure in which all atoms are tightly bound and not prone to dissolution in environmental and physiological media. This assumption is supported by available transformation/dissolution data (Grane, 2010) that indicate a very low release of pigment components. Transformation/dissolution of zirconium praseodymium yellow zircon (24-screening test according to OECD Series 29, loading of 100 mg/L) resulted in mean dissolved praseodymium concentrations of 3.05 µg/L Pr and 21.66 µg/L Pr, silicon concentrations of 0.13 µg/L Si and 0.02 µg/L Si at pH 6 and 8, respectively, whereas dissolved zirconium concentrations remained below the LOD (< 0.08 µg/L Zr). Since silicon does not have an ecotoxic potential, as confirmed by the absence of respective ecotoxicity reference values in the Metals classification tool (MeClas) database, and the dissolution of praseodymium is highest at pH 6, pH 6 is considered as pH that maximised metal release. Metal release at the 1 mg/L loading and pH 6 resulted in dissolved concentrations of 2.10 µg/L Pr and 0.17 µg/L Zr after 7 days and 0.79 µg/L Pr and < 0.08 µg/L Zr (< LOD) after 28 days whereas silicon concentrations remained below the LOD (< 0.07 µg/L Si) during the test. Thus, the rate and extent to which zirconium praseodymium yellow zircon produces soluble (bio)available ionic and other praseodymium-, silicon- or zirconium-bearing species in environmental media is limited. Hence, the pigment can be considered as environmentally and biologically inert during short- and long-term exposure. The poor solubility of zirconium praseodymium yellow zircon is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Reliable proprietary studies are not available for zirconium praseodymium yellow zircon. The potential for acute aquatic toxicity of the poorly soluble substance zirconium praseodymium yellow zircon is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 7 days at a loading rate of 1 mg/L with the lowest acute ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest EC50/LC50 values for algae, invertebrates and fish. Acute ERVs were obtained from the Metals classification tool (MeClas) database as follows: Hazard information for praseodymium is not included in the MeClas database. Nevertheless, soluble praseodymium salts (Praseodymium trichloride, EC 233-794-4, CAS 10361-79-2; Praseodymium trinitrate, EC 233-796-5, CAS 10361-80-5) are self-classified as Aquatic Acute 1 (M-factor 1) indicative of an L(E)C50 of > 0.1 ≤ 1 mg/L (https://echa.europa.eu/information-on-chemicals/cl-inventory-database, accessed on 12.03.2021), which is applied to evaluate the aquatic hazard potential of zirconium praseodymium yellow zircon. An acute ERV for silicon has not been derived since a concern for short-term (acute) toxicity of silicon ions was not identified (see also OECD, 2004). The acute ERV for zirconium in the MeClas database amounts to 74 mg Zr/L. According to ECHA’s Guidance on the Application of the CLP Criteria (Version 5.0, July 2017), “Where the acute ERV for the metal ions of concern is greater than 1 mg/L the metals need not be considered further in the classification scheme for acute hazard.” Metal release in the T/D test at the 1 mg/L loading and pH 6 resulted in dissolved concentrations of 2.10 µg/L Pr and 0.17 µg/L Zr after 7 days, whereas silicon concentrations remained below the LOD (< 0.07 µg/L Si). Due to the lack of an aquatic hazard potential for silicon and zirconium ions and the fact that dissolved praseodymium concentrations were well below the respective L(E)C50 estimate of > 0.1 ≤ 1 mg/L, it can be concluded that the substance zirconium praseodymium yellow zircon is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).

Regarding the long-term toxicity, the poorly soluble substance zirconium praseodymium yellow zircon is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 28 days at a loading rate of 1 mg/L with the lowest chronic ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The ERVs are based on the lowest NOEC/EC10 values for algae, invertebrates and fish. Chronic ERVs were obtained from the Metals classification tool (MeClas) database as follows: Hazard information for praseodymium is not included in the MeClas database. Nevertheless, soluble praseodymium salts (Praseodymium trichloride, EC 233-794-4, CAS 10361-79-2; Praseodymium trinitrate, EC 233-796-5, CAS 10361-80-5) are self-classified as Aquatic Chronic 1 (M-factor 1) indicative of a NOEC/EC10 of > 0.01 ≤ 0.1 mg/L (https://echa.europa.eu/information-on-chemicals/cl-inventory-database, accessed on 12.03.2021), which is applied to evaluate the aquatic hazard potential of zirconium praseodymium yellow zircon. A chronic ERV for silicon has not been derived since a concern for long-term (chronic) toxicity of silicon ions was not identified (see also OECD, 2004). A chronic ERV has also not been derived for zirconium. Metal release in the T/D test at the 1 mg/L loading and pH 6 resulted in dissolved concentrations of 0.79 µg/L Pr and < 0.08 µg/L Zr (< LOD) after 28 days, whereas silicon concentrations remained also below the LOD (< 0.07 µg/L Si). Due to the lack of an aquatic hazard potential for silicon and zirconium ions and the fact that dissolved praseodymium concentrations were well below the respective NOEC/EC10 estimate of > 0.01 ≤ 0.1 mg/L, it can be concluded that the substance zirconium praseodymium yellow zircon is not sufficiently soluble to cause long-term toxicity at the level of the chronic ERVs (expressed as NOEC/EC10).

In accordance with Figure IV.4 “Classification strategy for determining acute aquatic hazard for metal compounds” and Figure IV.5 „Classification strategy for determining long-term aquatic hazard for metal compounds “of ECHA Guidance on the Application of the CLP Criteria (Version 5.0, July 2017) and section 4.1.2.10.2. of Regulation (EC) No 1272/2008, the substance zirconium praseodymium yellow zircon is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Zirconium praseodymium yellow zircon is not classified as dangerous for the aquatic environment, an aquatic PNEC cannot be derived, thus not indicating a hazard to the aquatic environment. In these circumstances there are also not unclassified hazards to the soil compartment because toxicity to aquatic organisms is used as an indicator of concern for soil organisms and a screening risk characterisation (using the equilibration partitioning method to derive a PNEC for soil) cannot be undertaken. Thus, zirconium praseodymium yellow zircon does not have a “non-classified hazard” potential.

Praseodymium (Pr) is a lithophile rare earth element with two main oxidation states (Pr+3 and Pr+4) and an upper continental crust abundance of 7.1 mg/kg. Praseodymium forms several minerals and displays a very low mobility under naturally conditions (Reimann and de Caritat 1998).

Silicon, at about 28%, is the second most abundant element in the Earth’s crust after oxygen, and is mainly found in silica or silicate forms. It is a major constituent of nearly all rocks. Quartz, SiO2, is the most resistant mineral in soil. Quartz, because of its very low aqueous solubility, may be considered unreactive, and it is one of the residual minerals remaining in soil after other minerals have altered or dissolved.

Zirconium with an average crustal abundance of 162 mg/kg is a lithophile metallic element, forms several minerals, including zircon ZrSiO4 and also displays very low mobility under most environmental conditions, mainly due to the stability of the principal host mineral zircon and the low solubility of the hydroxide Zr(OH)4 (Salminen et al. 2005).

Monitoring data for elemental praseodymium, silicon and zirconium background concentrations in soil are provided by the FOREGS Geochemical Baseline Mapping Programme that offers high quality, multi-purpose homogeneous environmental geochemical baseline data for Europe (Salminen et al. 2005).

The FOREGS dataset for EU-27 countries plus UK and Norway reports metal concentrations for 830 (Pr) and 833 (Si and Zr) topsoil samples. Baseline praseodymium levels in topsoil range from 0.3 to 31.6 mg/kg with 5th, 50th and 95th percentiles of 1.5, 5.6 and 11.7 mg/kg, respectively. Baseline silicon levels in topsoil range from 6,874.4 to 452,307.1 mg/kg with 5th, 50th and 95th percentiles of 159,055.5, 317,531.2 and 415,680.6 mg/kg, respectively. Baseline zirconium levels in topsoil range from 5.0 to 1,060.0 mg/kg with 5th, 50th and 95th percentiles of 91.0, 231.0 and 466.6 mg/kg, respectively. Taking into account the high quality and representativeness of the data set, the 95th percentiles of 11.7 mg/kg Pr, 415,680.6 mg/kg Si and 466.6 mg/kg Zr can be regarded as representative background concentrations of praseodymium, silicon and zirconium in topsoil of EU countries.

Additionally, praseodymium, silicon and zirconium concentrations in soils were determined in the GEMAS project (Geochemical Mapping of Agricultural and Grazing land Soil), that offers high quality harmonized, freely and interoperable geochemical data for the top layer of agricultural and grazing land soil (Reimann et al. 2014). For the EU-27, UK and Norway, 1,867 and 1,781 samples of agricultural and grazing land soil were analysed. Praseodymium levels (only available as mobile metal ion fraction and agricultural soil) range from < 0.001 (< LOQ) to 3.0 mg/kg with 5th, 50th and 95th percentiles of < 0.001 (< LOQ), 0.02 and 0.2 mg/kg, respectively. Silicon levels of agricultural soil range from 11,499.0 to 448,274.0 mg/kg with 5th, 50th and 95th percentiles of 156,447.5, 311,829.0 and 417,708.0 mg/kg, respectively. In grazing land, soil concentrations of silicon range from 7,058.0 to 450,293.0 mg/kg with 5th, 50th and 95th percentiles of 133,489.0, 299,650.0 and 409,396.0 mg/kg, respectively. Zirconium levels of agricultural soil range from < 0.1 (< LOQ) to 165.2 mg/kg with 5th, 50th and 95th percentiles of 0.2, 1.7 and 9.0 mg/kg, respectively. In grazing land, soil concentrations of zirconium range from < 0.1 (< LOQ) to 375.9 mg/kg with 5th, 50th and 95th percentiles of 0.2, 1.5 and 9.1 mg/kg, respectively. Representative ambient silicon and zirconium concentrations (95th percentiles) of agricultural soil amount to 417,708.0 mg/kg Si and 9.0 mg/kg Zr and for grazing land soil to 409,396.0 mg/kg Si and 9.1 mg/kg Zr according to the GEMAS dataset. For praseodymium, only the mobile metal ion fraction was measured in agricultural soil and the representative ambient concentration (95th percentile) amounts to 0.2 mg/kg.

Regarding essentiality, whereas praseodymium and zirconium are non-essential elements, having no known biological roles, silicon is considered necessary for various functions in some species, including diatom algae, gastropods and mammals. Silicon deficiency in animals may lead to delays in growth, bone deformations and abnormal skeletal development, and one of the symptoms of silicon deficiency is aberrant connective and bone tissue metabolism (Pérez-Granados and Vaquero, 2002).

Considering abundance and/or bioavailability, the potential of praseodymium, silicon and zirconium ions for toxicity to terrestrial organisms can be expected to be low.

Zirconium praseodymium yellow zircon is not classified as harmful, toxic or very toxic to aquatic life or may cause long lasting harmful effects to aquatic life. Zirconium praseodymium yellow zircon is also not an unclassified hazard to the aquatic environment. Based on the poor solubility, bioavailability, lack of a potential for bioaccumulation and toxicity to aquatic organisms and considering ubiquitousness and/or bioavailability of praseodymium, silicon and zirconium in soil, zirconium praseodymium yellow zircon is also not considered an unclassified hazard to the soil compartment. Results of the chemical safety assessment do not indicate the need to investigate further the effects of zirconium praseodymium yellow zircon on soil organisms. Therefore, the study on the long-term toxicity to soil invertebrates does not need to be conducted in accordance with Column 2 of Information Requirement 9.4.4., Annex X, Commission Regulation (EU) 1907/2006.

References

OECD (2004) SIDS Initial Assessment Profile Silicon dioxide, Silicic acid, aluminum sodium salt, Silicic acid, calcium salt. SIAM 19, 19-22 October 2004.

Pérez-Granados and Vaquero (2002) Silicon, aluminium, arsenic and lithium: Essentiality and human health implications. The Journal of Nutrition Health and Aging 6/2:154-62.

Reimann et al. (2014) Chemistry of Europe’s agricultural soils - Part A: Methodology and interpretation of the GEMAS data set.

Reimann and de Caritat (1998) Chemical elements in the environment – Factsheets for geochemist and environmental scientist. Springer-Verlag, Berlin-Heidelberg, 398 pp.

Salminen et al. (2005) Geochemical Atlas of Europe - Part 1: Background information, Methodology and Maps. EuroGeoSurveys.
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
data waiving: supporting information
Reference
Endpoint:
monitoring data
Type of information:
other: report
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
no guideline required
Principles of method if other than guideline:
Evaluation and summary of high quality environmental geochemical data for Europe, which is provided by the Forum of European Geological Surveys (FOREGS) and the European Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS), with respect to silicon concentrations in stream water, stream sediment and topsoil, as well as in agricultural soil and grazing land.
GLP compliance:
no
Type of measurement:
other: Geochemical background and ambient silicon concentrations in different environmental compartments across Europe
Media:
other: Natural stream water, stream sediment and topsoil, as well as agricultural and grazing land soils
Details on sampling:
FOREGS and GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania, Bosnia and Switzerland were excluded from further analysis.

FOREGS:
- The FOREGS sampling grid was based on GTN grid cells developed for Global Geochemical Baseline mapping. This grid divides the entire land surface into 160 km x 160 km cells covering an area of 4,500,000 km2.
- Sampling methodology, preparation and analysis are described by Salminen et al. (2005).
- FOREGS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania and Switzerland were excluded from further analysis.
- A total of 795 stream water samples of silicon dioxide and 839 sediment samples of silicon dioxide were processed in the FOREGS-program, including 743 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment.
- The FOREGS dataset reports silicon/silicon dioxide concentrations for 833 topsoil samples sampled on a grid across Europe. A topsoil sample was taken at each site from 0-25 cm (excluding material from the organic layer where present).
- Reported silicon dioxide concentrations were converted into silicon concentrations.
- High quality and consistency of the obtained data were ensured by using standardised sampling methods and by treating and analysing all samples in the same laboratory of each country.

GEMAS:
- Samples from 33 out of 38 European countries were analysed to develop a suitable harmonised geochemical data base for soils. The sampling started in the spring 2008 and the first four months of 2009.
- The whole GEMAS project area of 5,600,000 km2 was divided into a grid with 50 km x 50 km cells.
- To generate harmonised data sets, all project samples were processed by a central sample preparation facility in Slovakia.
- GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Bosnia and Switzerland were excluded from further analysis.
- The GEMAS dataset reports silicon concentrations of 1,867 samples from the regularly ploughed layer (Ap-horizon) of agricultural land (arable land; 0 - 20 cm) and of 1,781 samples from the top layer of grazing land (soil under permanent grass cover; 0 - 10 cm) sampled on a grid across Europe.

FOREGS DATABASE STREAM WATER/SEDIMENT:

- Sampled stream water and sediments cover a wide range of environmental conditions. Water parameters such as pH, hardness and organic carbon concentrations extend over several magnitudes. Silicon water levels range from 0.05 to 33.7 mg/L with 5th, 50th and 95th percentiles of 0.8, 3.7 and 8.7 mg/L, respectively.

- In the sediment, silicon concentrations range from 11,691.1 to 439,586.6 mg/kg with 5th, 50th and 95th percentiles of 161,384.4, 290,875.4 and 385,246.2 mg/kg, respectively (Table 1).

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 8.7 mg/L can be regarded as representative background concentration for dissolved silicon in European surface waters and the 95th percentile of 385,246.2 mg/kg as representative background concentration of silicon in European stream sediments.

- Regarding the partitioning of silicon in the water column, stream water/sediment partition coefficients range from 7,056 to 5,290,000 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log Kp value of 4.87 is derived.

Table 1: Water parameters and silicon/silicon dioxide concentrations of stream sediment and stream water and respective partitioning.

Parameter

#

Unit

Min.

Max.

5th P

50th P

water

pH 1

735 2

-

9.80

4.50

8.50

7.70

water

Ca

743

mg/L

0.23

592.00

1.64

42.70

water

Cl

743

mg/L

0.14

4,560.00

0.49

9.32

water

HCO3

741 3

mg/L

0.69

1,804.42

5.36

131.67

water

K

743

mg/L

< 0.01

182.00

0.15

1.64

water

Mg

743

mg/L

0.05

230.00

0.46

6.22

water

Na

743

mg/L

0.23

4,030.00

1.00

6.76

water

NO3

743

mg/L

< 0.04

107.00

< 0.04

3.10

water

DOC

741 4

mg/L

< 0.50

57.94

0.60

4.79

water

SO42-

743

mg/L

< 0.30

2,420.00

1.18

17.10

water

SiO2

743

mg/L

0.10

72.00

1.66

8.00

water

Si 5

743

mg/L

0.05

33.67

0.78

3.74

sediment

SiO2

743

%

2.50

94.00

34.51

62.20

sediment

Si 5

743

mg/kg

11,691.13

439,586.58

161,384.39

290,875.37

Partitioning (Kp)

Si (sed/water)

743

L/kg

7,056

5,290,000

26,762

73,789

Log Kp

Si (sed/water)

743

-

3.85

6.72

4.43

4.87

Statistics are based on H+ concentrations rather than pH.

Removal of 2 outliers < pH 4.3 and 6 negative values.

Removal of 2 outliers < 0.01.

Removal of 1 outlier > 70 mg/L and 1 negative values.

5 Values converted from SiO2.

FOREGS DATABASE Background soil concentrations

- Sampled soils cover a wide range of environmental conditions. Soil parameters, including pH and TOC, cover several magnitudes.

- Baseline silicon levels in topsoil range from 6,874.4 to 452,306.5 mg/kg with 5th, 50th and 95th percentiles of 159,055.5, 317,531.2 and 415,680.6 mg/kg, respectively (see Table 2)

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 415,680.6 mg/kg can be regarded as representative background concentration of silicon in topsoil of EU countries.

Table 2: Concentrations of silicon/silicon dioxide in topsoil samples.

Parameter

Unit

#

Min.

Max.

5th P

50th P

95th P

pH 1

-

802

7.55

3.38

7.31

5.49

4.28

TOC

%

799

0.07

46.61

0.56

1.72

5.86

SiO2

%

833

1.47

96.72

34.01

67.90

88.89

Si 2

mg/kg

833

6,874.4

452,306.5

159,055.5

317,531.2

415,680.6

1 Statistics are based on H+ concentrations rather than pH.

2 Values converted from SiO2.

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Silicon levels of agricultural soil range from 11,499.0 to 448,274.0 mg/kg with 5th, 50th and 95th percentiles of 156,447.5, 311,829.0 and 417,708.0 mg/kg, respectively (see Table 3). In grazing land, soil concentrations of silicon range from 7,058.0 to 450,293.0 mg/kg with 5th, 50th and 95th percentiles of 133,489.0, 299,650.0 and 409,396.0 mg/kg, respectively (see Table 4)

Table 3: Agricultural soil concentrations.

Parameter

Unit

Method

#

Min.

Max.

5th P

50th P

95th P

CEC

meq/100g

AAS

1,867

1.80

48.30

6.10

15.80

33.30

pH (CaCl2)

pH

pH-meter

1,867

3.32

7.98

4.14

5.71

7.45

TOC

%

IR

1,854

0.40

46.00

0.70

1.70

5.67

Silicon

mg/kg

XRF

1,867

11,499.00

448,274.00

156,447.50

311,829.00

417,708.00

Table 4: Grazing land soil concentrations.

Parameter

Unit

Method

#

Min.

Max.

5th P

50th P

95th P

CEC

meq/100g

AAS

1,781

2.54

49.88

8.27

17.96

37.74

pH (CaCl2)

pH

pH-meter

1,780

3.26

8.06

4.03

5.38

7.45

TOC

%

IR

1,780

0.41

49.00

0.94

2.80

11.05

Silicon

mg/kg

XRF

1,781

7,058.00

450,293.00

133,489.00

299,650.00

409,396.00

Conclusions:
Representative background or ambient concentrations of silicon/silicion dioxide in environmental compartments are tabulated below.

compartment, unit, concentration (50th P), concentration (95th P)
background stream water, mg/L SiO2, 8.0, 18.6
background stream water, mg/L Si, 3.7*, 8.7*
background stream water sediment, % SiO2, 62.2, 82.4
background stream water sediment, mg/kg Si, 290,875.4*, 385,246.2*
background topsoil, % SiO2, 67.9, 88.9
background topsoil, mg/kg Si, 317,531.2*, 415,680.6*
agricultural soil, mg/kg Si, 311,829.0, 417,708.0
grazing land soil, mg/kg Si, 299,650.0, 409,396.0
* based on measured SiO2.

Based on the FOREGS dataset, the 95th percentile of 8.7 mg/L can be regarded as representative background concentration of dissolved silicon in European surface waters and the 95th percentile of 385,246.2 mg/kg as representative background concentration of European stream sediments. Regarding the respective partitioning between sediment and water, a European median log Kp value of 4.87 is derived.

Based on the FOREGS dataset, the 95th percentile of 415,680.6 mg/kg can be regarded as representative background concentration of silicon in topsoil of EU countries. Representative silicon concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 417,708.0 and 409,396.0 mg/kg, respectively, according to the GEMAS dataset.
Reason / purpose for cross-reference:
data waiving: supporting information
Reference
Endpoint:
monitoring data
Type of information:
other: report
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
no guideline required
Principles of method if other than guideline:
Evaluation and summary of high quality environmental geochemical data for Europe, which is provided by the Forum of European Geological Surveys (FOREGS) and the European Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS), with respect to zirconium concentrations in stream water, stream sediment and topsoil, as well as in agricultural soil and grazing land.
GLP compliance:
no
Type of measurement:
other: Geochemical background and ambient zirconium concentrations in different environmental compartments across Europe
Media:
other: Natural stream water, stream sediment and topsoil, as well as agricultural and grazing land soils
Details on sampling:
FOREGS and GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania, Bosnia and Switzerland were excluded from further analysis.

FOREGS:
- The FOREGS sampling grid was based on GTN grid cells developed for Global Geochemical Baseline mapping. This grid divides the entire land surface into 160 km x 160 km cells covering an area of 4,500,000 km2.
- Sampling methodology, preparation and analysis are described by Salminen et al. (2005).
- FOREGS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania and Switzerland were excluded from further analysis.
- A total of 795 stream water samples and 839 sediment samples were processed in the FOREGS-program, including 744 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment.
- The FOREGS dataset reports zirconium concentrations for 833 topsoil samples. A topsoil sample was taken at each site from 0-25 cm (excluding material from the organic layer where present).
- High quality and consistency of the obtained data were ensured by using standardised sampling methods and by treating and analysing all samples in the same laboratory of each country.

GEMAS:
- Samples from 33 out of 38 European countries were analysed to develop a suitable harmonised geochemical data base for soils. The sampling started in the spring 2008 and the first four months of 2009.
- The whole GEMAS project area of 5,600,000 km2 was divided into a grid with 50 km x 50 km cells.
- To generate harmonised data sets, all project samples were processed by a central sample preparation facility in Slovakia.
- GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Bosnia and Switzerland were excluded from further analysis.
- The GEMAS dataset reports zirconium concentrations of 1,867 samples from the regularly ploughed layer (Ap-horizon) of agricultural land (arable land; 0-20 cm) and of 1,781 samples from the top layer of grazing land (soil under permanent grass cover; 0-10 cm) sampled on a grid across Europe.

FOREGS DATABASE STREAM WATER/SEDIMENT:

- Sampled stream water and sediments cover a wide range of environmental conditions. Water parameters such as pH, hardness and organic carbon concentrations extend over several magnitudes. Zirconium water levels range from < 0.002 (< LOQ) to 2.4 µg/L with 5th, 50th and 95th percentiles of 0.003, 0.05 and 0.5 µg/L, respectively.

- In the sediment, zirconium concentrations range from 1.0 to 9,942.0 mg/kg with 5th, 50th and 95th percentiles of 118.5, 404.5 and 1,312.6 mg/kg, respectively (see Table 1).

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 0.5 µg/L can be regarded as representative background concentration for dissolved zirconium in European surface waters and the 95th percentile of 1,312.6 mg/kg as representative background concentration of zirconium in European stream sediments.

- Regarding the partitioning of zirconium in the water column, stream water/sediment partition coefficients range from 125,000 to 1,060,000,000 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log Kp value of 6.94 is derived.

Table 1: Water parameters and zirconium concentrations of stream sediment and stream water and respective partitioning.

Parameter

#

Unit

Min.

Max.

5th P

50th P

95th P

water

pH 1

736 2

-

9.80

4.50

8.50

7.70

6.10

water

Ca

744

mg/L

0.23

592.00

1.64

42.63

148.05

water

Cl

744

mg/L

0.14

4,560.00

0.49

9.36

71.43

water

HCO3

742 3

mg/L

0.69

1,804.42

5.37

129.69

373.80

water

K

744

mg/L

< 0.01

182.00

0.15

1.64

9.85

water

Mg

744

mg/L

0.05

230.00

0.46

6.23

38.67

water

Na

744

mg/L

0.23

4,030.00

1.00

6.76

48.35

water

NO3

744

mg/L

< 0.04

107.00

< 0.04

3.10

39.87

water

DOC

742 4

mg/L

< 0.50

57.94

0.60

4.80

23.05

water

SO42-

744

mg/L

< 0.30

2,420.00

1.18

17.03

166.99

water

Zr

744

µg/L

< 0.002

2.41

0.003

0.05

0.48

sediment

Zr

744

mg/kg

1.00

9,942.00

118.45

404.50

1,312.55

Partitioning (Kp)

Zr (sed/water)

744

L/kg

125,000

1,060,000,000

724,684

8,804,023

160,216,667

Log Kp

Zr (sed/water)

744

-

5.10

9.03

5.86

6.94

8.20

Statistics are based on H+ concentrations rather than pH.

Removal of 2 outliers < pH 4.3 and 6 negative values.

Removal of 2 outliers < 0.01.

Removal of 1 outlier > 70 mg/L and 1 negative values.

FOREGS DATABASE Background soil concentrations

- Sampled soils cover a wide range of environmental conditions. Soil parameters, including pH and TOC, cover several magnitudes.

- Baseline zirconium levels in topsoil range from 5.0 to 1,060.0 mg/kg with 5th, 50th and 95th percentiles of 91.0, 231.0 and 466.6 mg/kg, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 466.6 mg/kg can be regarded as representative background concentration of zirconium in topsoil of EU countries.

Table 2: Concentrations of zirconium in topsoil samples.

Parameter

Unit

#

Min.

Max.

5th P

50th P

95th P

pH 1

-

802

7.55

3.38

7.31

5.49

4.28

TOC

%

799

0.07

46.61

0.56

1.72

5.86

Zr

mg/kg

833

5.00

1,060.00

91.00

231.00

466.60

1 Statistics are based on H+ concentrations rather than pH.

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Zirconium levels of agricultural soil range from < 0.1 (< LOQ) to 165.2 mg/kg with 5th, 50th and 95th percentiles of 0.2, 1.7 and 9.0 mg/kg, respectively (see Table 3). In grazing land, soil concentrations of zirconium range from < 0.1 (< LOQ) to 375.9 mg/kg with 5th, 50th and 95th percentiles of 0.2, 1.5 and 9.1 mg/kg, respectively (see Table 4).

Table 3: Agricultural soil concentrations.

Parameter

Unit

Method

#

Min.

Max.

5th P

50th P

95th P

CEC

meq/100g

AAS

1,867

1.80

48.30

6.10

15.80

33.30

pH (CaCl2)

pH

pH-meter

1,867

3.32

7.98

4.14

5.71

7.45

TOC

%

IR

1,854

0.40

46.00

0.70

1.70

5.67

Zirconium

mg/kg

AR

1,867

< 0.10

165.22

0.15

1.65

8.99

Zirconium

mg/kg

XRF

1,867

4.00

963.00

98.30

255.00

506.4

Zirconium

mg/kg

MMI

1,867

< 0.005

1.85

0.01

0.05

0.31

Table 4: Grazing land soil concentrations.

Parameter

Unit

Method

#

Min.

Max.

5th P

50th P

95th P

CEC

meq/100g

AAS

1,781

2.54

49.88

8.27

17.96

37.74

pH (CaCl2)

pH

pH-meter

1,780

3.26

8.06

4.03

5.38

7.45

TOC

%

IR

1,780

0.41

49.00

0.94

2.80

11.05

Zirconium

mg/kg

AR

1,781

< 0.10

375.89

0.16

1.54

9.12

Zirconium

mg/kg

XRF

1,781

4.00

871.00

90.00

241.00

477.00

Conclusions:
Representative background or ambient concentrations of zirconium in environmental compartments are tabulated below.

compartment, unit, concentration (50th P), concentration (95th P)
background stream water, µg/L Zr, 0.05, 0.5
background stream water sediment, mg/kg Zr, 404.5, 1,312.6
background topsoil, mg/kg Zr, 231.0, 466.6
agricultural soil, mg/kg Zr, 1.7, 9.0
grazing land soil, mg/kg Zr, 1.5, 9.1

Based on the FOREGS dataset, the 95th percentile of 0.5 µg/L can be regarded as representative background concentration of dissolved zirconium in European surface waters and the 95th percentile of 1,312.6 mg/kg as representative background concentration of European stream sediments. Regarding the respective partitioning between sediment and water, a European median log Kp value of 6.94 is derived.

Based on the FOREGS dataset, the 95th percentile of 466.6 mg/kg can be regarded as representative background concentration of zirconium in topsoil of EU countries. Representative zirconium concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 9.0 and 9.1 mg/kg, respectively, according to the GEMAS dataset.
Reason / purpose for cross-reference:
data waiving: supporting information
Reference
Endpoint:
monitoring data
Type of information:
other: report
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
no guideline required
Principles of method if other than guideline:
Evaluation and summary of high quality environmental geochemical data for Europe, which is provided by the Forum of European Geological Surveys (FOREGS) and the European Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS), with respect to praseodymium concentrations in stream water, stream sediment and topsoil, as well as in agricultural soil and grazing land.
GLP compliance:
no
Type of measurement:
other: Geochemical background and ambient praseodymium concentrations in different environmental compartments across Europe
Media:
other: Natural stream water, stream sediment and topsoil, as well as agricultural and grazing land soils
Details on sampling:
FOREGS and GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania, Bosnia and Switzerland were excluded from further analysis.

FOREGS:
- The FOREGS sampling grid was based on GTN grid cells developed for Global Geochemical Baseline mapping. This grid divides the entire land surface into 160 km x 160 km cells covering an area of 4,500,000 km2.
- Sampling methodology, preparation and analysis are described by Salminen et al. (2005).
- FOREGS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Albania and Switzerland were excluded from further analysis.
- A total of 795 stream water samples and 835 sediment samples were processed in the FOREGS-program, including 741 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment.
- The FOREGS dataset reports praseodymium concentrations for 830 topsoil samples sampled on a grid across Europe. A topsoil sample was taken at each site from 0-25 cm (excluding material from the organic layer where present).
- High quality and consistency of the obtained data were ensured by using standardised sampling methods and by treating and analysing all samples in the same laboratory of each country.

GEMAS:
- Samples from 33 out of 38 European countries were analysed to develop a suitable harmonised geochemical data base for soils. The sampling started in the spring 2008 and the first four months of 2009.
- The whole GEMAS project area of 5,600,000 km2 was divided into a grid with 50 km x 50 km cells.
- To generate harmonised data sets, all project samples were processed by a central sample preparation facility in Slovakia.
- GEMAS data for EU-27 countries plus UK and Norway were considered, i.e. data from non-EEA countries such as Bosnia and Switzerland were excluded from further analysis.
- The GEMAS dataset reports praseodymium concentrations for 1,867 samples from the regularly ploughed layer (Ap-horizon) of agricultural land (arable land; 0 - 20 cm) and for 1,781 samples from the top layer of grazing land (soil under permanent grass cover; 0 – 10 cm) sampled on a grid across Europe.

FOREGS DATABASE STREAM WATER/SEDIMENT:

- Sampled stream water and sediments cover a wide range of environmental conditions. Water parameters such as pH, hardness and organic carbon concentrations extend over several magnitudes. Praseodymium water levels range from < 0.002 µg/L (< LOQ) to 4.7 µg/L with 5th, 50th and 95th percentiles of < 0.002 µg/L (< LOQ), 0.01 and 0.2 µg/L, respectively.

- In the sediment, praseodymium concentrations range from 0.3 to125.0 mg/kg with 5th, 50th and 95th percentiles of 2.4, 7.4 and 24.3 mg/kg, respectively (Table 1).

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 0.2 µg/L can be regarded as representative background concentration for dissolved praseodymium in European surface waters and the 95th percentile of 24.3 mg/kg as representative background concentration of praseodymium in European stream sediments.

- Regarding the partitioning of praseodymium in the water column, stream water/sediment partition coefficients range from 1,957 to 43,700,000 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log Kp value of 5.92 is derived.

Table 1: Water parameters and praseodymium concentrations of stream sediment and stream water and respective partitioning.

 

Parameter

#

Unit

Min.

Max.

5th P

50th P

95th P

water

pH 1

733 2

-

9.80

4.50

8.50

7.70

6.10

water

Ca

741

mg/L

0.23

592.00

1.63

42.70

147.20

water

Cl

741

mg/L

0.14

4,560.00

0.49

9.05

67.43

water

HCO3

739 3

mg/L

0.69

1,804.42

5.36

131.37

374.27

water

K

741

mg/L

< 0.01

182.00

0.15

1.64

9.80

water

Mg

741

mg/L

0.05

230.00

0.46

6.18

37.94

water

Na

741

mg/L

0.23

4,030.00

1.00

6.76

48.26

water

NO3

741

mg/L

< 0.04

107.00

< 0.04

3.10

39.90

water

DOC

739 4

mg/L

< 0.50

57.94

0.60

4.79

23.07

water

SO42-

737

mg/L

< 0.30

2,420.00

1.18

17.10

166.93

water

Pr

741

µg/L

< 0.002

4.70

< 0.002

0.01

0.20

sediment

Pr

741

mg/kg

0.30

125.00

2.40

7.40

24.30

Partitioning (Kp)

Pr (sed/water)

741

L/kg

1,957

43,700,000

34,884

833,333

6,100,000

Log Kp

Pr (sed/water)

741

-

3.29

7.64

4.54

5.92

6.79

Statistics are based on H+ concentrations rather than pH.

Removal of 2 outliers < pH 4.3 and 6 negative values.

Removal of 2 outliers < 0.01.

Removal of 1 outlier > 70 mg/L and 1 negative values.

FOREGS DATABASE Background soil concentrations

- Sampled soils cover a wide range of environmental conditions. Soil parameters, including pH and TOC, cover several magnitudes.

- Baseline praseodymium levels in topsoil range from 0.3 to 31.6 mg/kg with 5th, 50th and 95th percentiles of 1.5, 5.6 and 11.7 mg/kg, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 95th percentile of 11.7 mg/kg can be regarded as representative background concentration of praseodymium in topsoil of EU countries.

Table 2: Concentrations of praseodymium in topsoil samples.

Parameter

Unit

#

Min.

Max.

5th P

50th P

95th P

pH 1

-

804

7.55

3.38

7.31

5.49

4.28

TOC

%

803

0.07

46.61

0.56

1.72

5.86

Pr

mg/kg

830

0.29

31.60

1.46

5.61

11.70

1 Statistics are based on H+ concentrations rather than pH.

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Praseodymium levels of agricultural soil (by MMI) range from < 0.001 (< LOQ) to 3.0 mg/kg with 5th, 50th and 95th percentiles of < 0.001 (< LOQ), 0.02 and 0.2 mg/kg, respectively (see Table 3).

Table 3: Agricultural soil concentrations.

Parameter

Unit

Method

#

Min.

Max.

5th P

50th P

95th P

CEC

meq/100g

AAS

1,867

1.80

48.30

6.10

15.80

33.30

pH (CaCl2)

pH

pH-meter

1,867

3.32

7.98

4.14

5.71

7.45

TOC

%

IR

1,854

0.40

46.00

0.70

1.70

5.67

Praseodymium

mg/kg

MMI

1,867

< 0.001

2.98

< 0.001

0.02

0.19

Conclusions:
Representative background or ambient concentrations of praseodymium in environmental compartments are tabulated below.

compartment, unit, concentration (50th P), concentration (95th P)
background stream water, µg/L Pr, 0.01, 0.2
background stream water sediment, mg/kg Pr, 7.4, 24.3
background topsoil, mg/kg Pr, 5.6, 11.7
agricultural soil (by MMI), mg/kg Pr, 0.02, 0.2

Based on the FOREGS dataset, the 95th percentile of 0.2 µg/L can be regarded as representative background concentration for dissolved praseodymium in European surface waters and the 95th percentile of 24.3 mg/kg as representative background concentration of European stream sediments. Regarding the respective partitioning between sediment and water, a European median log Kp value of 5.92 is derived

Based on the FOREGS dataset, the 95th percentile of 11.7 mg/kg can be regarded as representative background concentration of praseodymium in topsoil of EU countries. Representative praseodymium concentrations (95th percentile) of agricultural soil (i.e. ambient levels) amount to 0.2 mg/kg (for MMI extracts), according to the GEMAS dataset.

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion

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