Chromium tin calcium silicon sphene

Toxicity to terrestrial plants

Administrative data

Endpoint:

toxicity to terrestrial plants: 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 IX, Commission Regulation (EU) 1907/2006, ”These studies do not need to be conducted if direct and indirect exposure of the soil compartment is unlikely. In the absence of toxicity data for soil organisms, the equilibrium partitioning method may be applied to assess the hazard to soil organisms. Where the equilibrium partitioning method is applied to nanoforms, this shall be scientifically justified. The choice of the appropriate tests depends on the outcome of the chemical safety assessment. In particular for substances that have a high potential to adsorb to soil or that are very persistent, the registrant shall consider long-term toxicity testing instead of short-term.”

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.”

Chromium tin calcium silicon sphene 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 (Pardo Martinez, 2013) that indicate a very low release of pigment components at pH 8. Transformation/dissolution of chromium tin calcium silicon sphene (24-screening test according to OECD Series 29) at a loading of 100 mg/L and pH 6 and 8 resulted in chromium concentrations below the LOD (< 0.5 µg/L) while tin concentrations of 5.4 and 11.5 µg Sn/L were measured, respectively. Thus, metal release from the pigment is maximised at pH 8. The dissolved chromium concentrations remained also below the LOD (< 0.5 µg/L) after 7 and 28 days in the T/D test with 1 mg/L loading at pH 8 while dissolved tin concentrations amount to 2.2 and 3.8 µg Sn/L, respectively. Calcium and silicon were not considered in the T/D assessment since they do not have an ecotoxic potential as confirmed by the absence of respective ecotoxicity reference values in the Metals classification tool (MeClas) database (see also OECD 2002 and 2004). Thus, the rate and extent to which chromium tin calcium silicon sphene produces soluble (bio)available ionic and other calcium-, chromium-, silicon- and tin-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 chromium tin calcium silicon sphene is expected to determine its behaviour and fate in the environment, and subsequently its potential for ecotoxicity.

Proprietary studies are not available for chromium tin calcium silicon sphene. The poorly soluble substance chromium tin calcium silicon sphene is evaluated by comparing the dissolved metal ion levels resulting from the transformation/dissolution test after 7 and 28 days at a loading rate of 1 mg/L with the lowest acute and chronic ecotoxicity reference values (ERVs) as determined for the (soluble) metal ions. The acute and chronic ERVs are based on the lowest EC50/LC50 or NOEC/EC10 values for algae, invertebrates and fish, respectively, and were obtained from the Metals classification tool (MeClas) database as follows:

Acute ERVs for calcium and silicon are not available since a concern for short-term toxicity was not identified, respectively (see also OECD, 2002 and 2004). For trivalent chromium and tin ions, the acute ERVs are above 1 mg/L (>100 mg Cr3+/L; 9.8 mg Sn/L) and a concern for short-term (acute) toxicity was also not identified (no classification). According to ECHA 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.” Due to the lack of an acute aquatic hazard potential for calcium, chromium, silicon and tin ions and the fact that (after 7 days T/D at pH 8 and a loading of 1 mg/L) dissolved concentrations of chromium remained below the LOD (< 0.5 µg/L) and the tin concentration amounts to 2.2 µg Sn/L and is well below the lowest acute ERV of 9.8 mg Sn/L, it can be concluded that the substance chromium tin calcium silicon sphene is not sufficiently soluble to cause short-term toxicity at the level of the acute ERVs (expressed as EC50/LC50).

Regarding long-term toxicity, chronic ERVs for calcium and silicon are not available since a concern for long-term toxicity of calcium and silicon ions was not identified (see also OECD, 2002 and 2004). For trivalent chromium and tin ions, the chronic ERVs are above 1 mg/L, and a concern for long-term (chronic) toxicity was also not identified (no classification). According to ECHA Guidance on the Application of the CLP Criteria (Version 5.0, July 2017), ”Where the chronic ERV for the metal ions of concern corrected for the molecular weight of the compound (further called as chronic ERV compound) is greater than 1 mg/L, the metal compounds need not to be considered further in the classification scheme for long-term hazard.” Due to the lack of a chronic aquatic hazard potential for calcium, chromium, silicon and tin ions and the fact that (after 28 days T/D at pH 8 and a loading of 1 mg/L) dissolved concentrations of chromium remained below the LOD (< 0.5 µg/L) and tin concentration amount to 3.8 µg Sn/L whereas the respective chronic ERV is above 1 mg/L, it can be concluded that the substance chromium tin calcium silicon sphene 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 chromium tin calcium silicon sphene is poorly soluble and does not meet classification criteria for acute (short-term) and chronic (long-term) aquatic hazard.

Chromium tin calcium silicon sphene 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, chromium tin calcium silicon sphene does not have a “non-classified hazard” potential.

Calcium is a widespread refractory lithophile element and is the 5th most abundant element, constituting approximately 3% of the upper continental crust. Solutions of most soil types contain an excess of calcium, which constitutes more than 90% of the total cation concentration. Calcium is the most important cation governing the solubility of trace elements in soil. Divalent calcium (Ca2+) ions are held more strongly than monovalent ions on the negatively charged surfaces of clay minerals and organic matter (Salminen et al. 2005 and references therein).

Chromium is ubiquitous in soil and a constituent of several rock forming minerals. According to the EU RAR on chromates (ECB, 2005), “Chromium (III) has generally been shown to be less toxic than chromium (VI) to soil organisms…Since chromium (III) adsorbs more strongly onto soil than chromium (VI), it would again be expected that in soils, chromium (III) would be less toxic than chromium (VI)”.

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 (Salminen et al. 2005 and references therein).

Tin is a siderophile metallic element and relatively rare metal with an average crustal abundance of 2.1 mg Sn/kg. During weathering, the mobility of tin is highly pH dependent and, tin ions are strongly reducing and only present in acid and reducing environments. Soluble tin follows the behaviour of iron and aluminium and remains in the weathered residue along with hydroxides of these metals (Salminen et al. 2005 and references therein).

Monitoring data for elemental calcium, chromium, silicon and tin 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, UK and Norway reports metal concentrations of 833 (Ca, Si, Sn) and 825 (Cr) topsoil samples.

Baseline calcium levels in topsoil range from 185.8 to 340,693.1 mg Ca/kg with 5th, 50th and 95th percentiles of 891.9, 6,518.0 and 161,391.5 mg Ca/kg, respectively. Baseline chromium levels in topsoil range from 1.0 to 2,340.0 mg Cr/kg with 5th, 50th and 95th percentiles of 5.0, 22.0 and 69.8 mg Cr/kg, respectively. Baseline silicon levels (derived from silicon dioxide data) in topsoil range from 6,874 to 452,307 mg Si/kg with 5th, 50th and 95th percentiles of 159,056, 317,531 and 415,681 mg Si/kg, respectively. Baseline tin levels in topsoil range from < 1.0 (< LOQ) to 106.0 mg Sn/kg with 5th, 50th and 95th percentiles of 1.0 (< LOQ), 3.0 and 10.0 mg Sn/kg, respectively.

Based on the FOREGS dataset, the 95th percentiles of 161,391.5 mg Ca/kg, 69.8 mg Cr/kg, 415,681 mg Si/kg and 10.0 mg Sn/kg can be regarded as representative background concentrations of calcium, chromium, silicon and tin in topsoil of EU countries.

Additionally, calcium, chromium, silicon and tin 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. For the EU-27 plus UK and Norway, 1,867 samples of agricultural land soil and 1,781 samples of grazing land soil were analysed (Reimann et al. 2014).

Calcium levels of agricultural soil range from < 100.0 (< LOQ) to 347,847.3 mg Ca/kg with 5th, 50th and 95th percentiles of 558.7, 2,865.3 and 136,110.6 mg Ca/kg, respectively. In grazing land, soil concentrations of calcium range from < 100.0 (< LOQ) to 328,124.3 mg Ca/kg with 5th, 50th and 95th percentiles of 555.1, 3,019.7 and 137,576.2 mg Ca/kg, respectively. Chromium levels of agricultural soil range from 0.40 to 696.02 mg Cr/kg with 5th, 50th and 95th percentiles of 4.16, 19.87 and 67.16 mg Cr/kg, respectively. In grazing land, soil concentrations of chromium range from 0.78 to 576.74 mg Cr/kg with 5th, 50th and 95th percentiles of 3.87, 19.75 and 67.82 mg Cr/kg, respectively. Silicon levels of agricultural soil range from 11,499 to 448,274 mg Si/kg with 5th, 50th and 95th percentiles of 156,448, 311,829 and 417,708 mg Si/kg, respectively. In grazing land, soil concentrations of silicon range from 7,058 to 450,293 mg Si/kg with 5th, 50th and 95th percentiles of 133,489, 299,650 and 409,396 mg Si/kg, respectively. Tin levels of agricultural soil range from < 0.1 (< LOQ) to 30.4 mg Sn/kg with 5th, 50th and 95th percentiles of 0.2, 0.8 and 2.5 mg Sn/kg, respectively. In grazing land, soil concentrations of tin range from < 0.1 (< LOQ) to 158.3 mg Sn/kg with 5th, 50th and 95th percentiles of 0.3, 0.9 and 2.8 mg Sn/kg, respectively.

Representative calcium, chromium, silicon and tin concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 136,110.6 and 137,576.2 mg Ca/kg, 67.16 and 67.82 mg Cr/kg, 417,708 and 409,396 mg Si/kg, and 2.5 and 2.8 mg Sn/kg, respectively, according to the GEMAS dataset.

The potential essentiality of the pigment components calcium, chromium, silicon and tin can be summarized as follows:

According to OECD (2002), calcium is an essential constituent of the body of all animal species. “Calcium is essential for the formation of skeletons and the regulation of neural transmission, muscle contraction and coagulation of the blood… Calcium is known as an essential nutrient for higher plants and one of the basic inorganic elements of algae. Calcium plays crucial roles in strengthening cell walls and plant tissues, reducing the toxicity of soluble organic acids, elongating roots, and so on.”

“Chromium (III) is required by only some microorganisms for specific metabolic processes, such as glucose metabolism and enzyme stimulation. Chromium (III), in trace amounts, has been reported to be an essential component of animal nutrition and is most notably associated with glucose and fat metabolism (WHO, 2009).”

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).

According to the WHO (2005) and references therein, “tin is ubiquitous in animal tissues. There is evidence that tin is essential for growth in rats, but no essential function has been shown in other mammals, including humans.”

Chromium tin calcium silicon sphene is not classified as harmful, toxic or very toxic to aquatic life or may cause long lasting harmful effects to aquatic life. Chromium tin calcium silicon sphene is also not an unclassified hazard to the aquatic environment. Based on the poor solubility, bioavailability, and/or lack of a potential for bioaccumulation and toxicity to aquatic organisms and considering ubiquitousness and low potential for toxicity of calcium, chromium, silicon and tin in soil, chromium tin calcium silicon sphene 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 chromium tin calcium silicon sphene on soil organisms. Results of the chemical safety assessment do not indicate the need to investigate further the effects of chromium tin calcium silicon sphene on soil organisms. Therefore, the study on the short-term toxicity to terrestrial plants does not need to be conducted in accordance with Column 2 of Information Requirement 9.4.3., Annex IX, Commission Regulation (EU) 1907/2006.

References:

ECB (2005) European Union Risk Assessment Report: Chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate and potassium dichromate. EUR 21508 EN.

OECD (2002) SIDS Initial Assessment Report Calcium Chloride CAS N°:10043-52-4. SIAM 15, 22-25 October 2002.

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.

Salminen et al. (2005) Geochemical Atlas of Europe - Part 1: Background information, Methodology and Maps. EuroGeoSurveys.

WHO (2005) Concise International Chemical Assessment Document 65 (CICAD). Tin and inorganic tin compounds. International Programme of Chemical Safety (IPCS), WHO, Geneva.

WHO (2009) Concise International Chemical Assessment Document 76 (CICAD). Inorganic chromium (III) compounds. International Programme of Chemical Safety (IPCS), WHO, Geneva.

Cross-reference

Cross-reference 1

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 chromium 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 chromium 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 832 sediment samples were processed in the FOREGS-program, including 734 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment.
- The FOREGS dataset reports chromium concentrations for 825 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 chromium 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. Chromium water levels range from < 0.01 (< LOQ) to 43.0 µg/L with 5^th, 50^th and 95^th percentiles of 0.06, 0.4 and 1.8 µg/L, respectively.

- In the sediment, chromium concentrations range from 2.0 to 1,748.0 mg/kg with 5^th, 50^th and 95^th percentiles of 6.0, 21.0 and 63.0 mg/kg, respectively (Table 1).

-Taking into account the high quality and representativeness of the data set, the 95^th percentile of 1.8 µg/L can be regarded as representative background concentration for dissolved chromium in European surface waters and the 95^th percentile of 63.0 mg/kg as representative background concentration of chromium in European stream sediments.

-Regarding the partitioning of chromium in the water column, stream water/sediment partition coefficients range from 1,080 to 4,800,000 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe,a European median log Kp value of 4.75 is derived.

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

	Parameter	#	Unit	Min.	Max.	5^thP	50^thP	95^thP
water	pH ^1	726 ^2	-	9.80	4.50	8.50	7.70	6.10
water	Ca	734	mg/L	0.23	592.00	1.60	42.28	144.21
water	Cl	734	mg/L	0.14	4,560.00	0.49	8.95	69.08
water	HCO3	732^3	mg/L	0.69	1,804.42	5.34	128.01	370.00
water	K	734	mg/L	< 0.01	182.00	0.14	1.62	9.80
water	Mg	734	mg/L	0.05	230.00	0.46	6.15	36.81
water	Na	734	mg/L	0.23	4,030.00	1.00	6.66	48.30
water	NO3	734	mg/L	< 0.04	107.00	< 0.04	3.05	39.91
water	DOC	732 ^4	mg/L	< 0.50	57.94	0.60	4.84	23.11
water	SO4^2-	734	mg/L	< 0.30	2,420.00	1.18	16.79	164.56
water	Cr	734	µg/L	< 0.01	43.03	0.06	0.38	1.81
sediment	Cr	734	mg/kg	2.00	1,748.00	6.00	21.00	63.00
Partitioning (Kp)	Cr (sed/water)	734	L/kg	1,080	4,800,000	8,570	56,119	390,841
Log Kp	Cr (sed/water)	734	-	3.03	6.68	3.93	4.75	5.59

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

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

³ Removal of 2 outliers < 0.01.

⁴ 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 chromium levels in topsoil range from 1.0 to 2,340.0 mg/kg with5^th, 50^th and 95^th percentiles of 5.0, 22.0 and 69.8 mg/kg, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 95^th percentile of 69.8 mg/kg can be regarded as representative background concentration of chromium in topsoil of EU countries.

Table 2: Concentrations of chromium in topsoil samples.

Parameter	Unit	#	Min.	Max.	5^thP	50^thP	95^thP
pH ^1	-	798	7.55	3.38	7.31	5.49	4.29
TOC	%	805	0.07	46.61	0.55	1.72	5.87
Cr	mg/kg	825	1.00	2,340.00	5.00	22.00	69.80

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

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Chromium levels of agricultural soil range from 0.40 to 696.02 mg/kg with 5^th, 50^th and 95^th percentiles of 4.2, 19.9 and 67.2 mg/kg, respectively (see Table 3). In grazing land, soil concentrations of chromium range from 0.8 to 576.7 mg/kg with 5^th, 50^th and 95^th percentiles of 3.9, 19.8 and 67.8 mg/kg, respectively (see Table 4).

Table 3: Agricultural soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^thP	50^thP	95^thP
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
Chromium	mg/kg	AR	1,867	0.40	696.02	4.16	19.87	67.16
Chromium	mg/kg	XRF	1,867	2.00	6,133.00	14.00	58.00	191.00
Chromium	mg/kg	MMI	1,867	< 0.001	1.30	0.01	0.07	0.26

Table 4: Grazing land soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^thP	50^thP	95^thP
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
Chromium	mg/kg	AR	1,781	0.78	576.74	3.87	19.75	67.82
Chromium	mg/kg	XRF	1,781	2.00	6,594.00	13.00	59.00	187.00

Conclusions:

Representative background or ambient concentrations of chromium in environmental compartments are tabulated below:

compartment, unit, concentration (50th P), concentration (95th P)
background stream water, µg/L Cr, 0.4, 1.8
background stream water sediment, mg/kg Cr, 21.0, 63.0
background topsoil, mg/kg Cr, 22.0, 69.8
agricultural soil, mg/kg Cr, 19.9, 67.2
grazing land soil, mg/kg Cr, 19.8, 67.8

Based on the FOREGS dataset, the 95th percentile of 1.8 µg/L can be regarded as representative background concentration for dissolved chromium in European surface waters and the 95th percentile of 63.0 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 4.75 is derived.

Based on the FOREGS dataset, the 95th percentile of 69.8 mg/kg can be regarded as representative background concentration of chromium in topsoil of EU countries. Representative chromium concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 67.2 and 67.8 mg/kg, respectively, according to the GEMAS dataset.

Cross-reference 2

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 calcium 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 calcium 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 calcium and 839 sediment samples of calcium oxide were processed in the FOREGS-program, including 745 paired samples, i.e. samples with the same coordinates for the sampling location of stream water and sediment.
- The FOREGS dataset reports calcium/calcium oxide 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 calcium oxide concentrations were converted into calcium 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 calcium 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. Calcium water levels range from 0.2 to 592.0 mg/L with 5^th, 50^th and 95^th percentiles of 1.6, 42.7 and 148.0 mg/L, respectively.

- In the sediment, calcium concentrations range from 571.8 to 397,796.9 mg/kg with 5^th, 50^th and 95^th percentiles of 2,215.5, 16,009.1 and 185,633.8 mg/kg, respectively (Table 1).

- Taking into account the high quality and representativeness of the data set, the 95^th percentile of 148.0 mg/L can be regarded as representative background concentration for dissolved calcium in European surface waters and the 95^th percentile of 185,633.8 mg/kg as representative background concentration of calcium in European stream sediments.

- Regarding the partitioning of calcium in the water column, stream water/sediment partition coefficients range from 18 to 209,845 L/kg. Since FOREGS sampled on a grid aiming to equally represent geochemical baseline concentrations across Europe, a European median log K_p value of 2.73 is derived.

Table 1: Water parameters and calcium/calcium oxide concentrations of stream sediment and stream water and respective partitioning.

	Parameter	#	Unit	Min.	Max.	5^thP	50^thP	95^thP
water	pH ^1	737 ^2	-	9.80	4.50	8.50	7.70	6.10
water	Cl	745	mg/L	0.14	4,560.00	0.49	9.40	71.19
water	HCO3	743 ^3	mg/L	0.69	1,804.42	5.38	131.37	373.60
water	K	745	mg/L	< 0.01	182.00	0.15	1.65	9.85
water	Mg	745	mg/L	0.05	230.00	0.46	6.24	38.63
water	Na	745	mg/L	0.23	4,030.00	1.00	6.76	48.34
water	NO3	745	mg/L	< 0.04	107.00	< 0.04	3.10	39.86
water	DOC	743 ^4	mg/L	< 0.50	57.94	0.60	4.79	23.04
water	SO4^2-	745	mg/L	< 0.30	2,420.00	1.18	17.10	166.99
water	Ca	745	mg/L	0.23	592.00	1.64	42.70	148.00
sediment	CaO	745	%	0.08	55.66	0.31	2.24	25.97
sediment	Ca ^5	745	mg/kg	571.75	397,796.88	2,215.54	16,009.07	185,633.78
Partitioning (Kp)	Ca (sed/water)	745	L/kg	18	209,845	67	532	8,356
Log Kp	Ca (sed/water)	745	-	1.25	5.32	1.83	2.73	3.92

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

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

³ Removal of 2 outliers < 0.01.

⁴ Removal of 1 outlier > 70 mg/L and 1 negative values.

⁵ Values converted from CaO.

FOREGS DATABASE Background soil concentrations

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

- Baseline calcium levels in topsoil range from 185.8 to 340,693.1 mg/kg with 5^th, 50^th and 95^th percentiles of 891.9, 6,518.0 and 161,391.5 mg/kg, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 95^th percentile of 161,391.5 mg/kg can be regarded as representative background concentration of calcium in topsoil of EU countries

Table 2: Concentrations of calcium/calcium oxide in topsoil samples.

Parameter	Unit	#	Min.	Max.	5^thP	50^thP	95^thP
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
CaO	%	833	0.03	47.67	0.12	0.91	22.58
Ca ^2	mg/kg	833	185.8	340,693.1	891.9	6,518.0	161,391.5

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

² Values converted from CaO.

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Calcium levels of agricultural soil range from < 100.0 (< LOQ) to 347,847.3 mg/kgwith 5^th, 50^th and 95^th percentiles of 558.7, 2,865.3 and 136,110.6 mg/kg, respectively (see Table 3). In grazing land, soil concentrations of calcium range from < 100.0 (< LOQ) to 328,124.3 mg/kg with 5^th, 50^th and 95^th percentiles of 555.1, 3,019.7 and 137,576.2 mg/kg, respectively (seeTable 4).

Table 3: Agricultural soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^th P	50^th P	95^th 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
Calcium	mg/kg	AR	1,867	< 100.00	347,847.34	558.73	2,865.32	136,110.58
Calcium	mg/kg	XRF	1,867	86.00	378,148.00	1,310.10	8,862.00	144,976.90
Calcium	mg/kg	MMI	1,867	< 10.00	2,490.00	90.00	550.00	1,314.00

Table 4: Grazing land soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^thP	50^thP	95^thP
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
Calcium	mg/kg	AR	1,781	< 100.00	328,124.30	555.09	3,019.67	137,576.24
Calcium	mg/kg	XRF	1,781	50.00	362,803.00	1,265.00	7,847.00	147,035.00

Conclusions:

Representative background or ambient concentrations of calcium/calcium oxide in environmental compartments are tabulated below.

compartment, unit, concentration (50th P), concentration (95th P)
background stream water, mg/L Ca, 42.7, 148.0
background stream water sediment, % CaO, 2.2, 26.0
, mg/kg Ca, 16,009.1*, 185,633.8*
background topsoil, % CaO, 0.9, 22.6
, mg/kg Ca, 6,518.0*, 161,391.5*
agricultural soil, mg/kg Ca, 2,865.3, 136,110.6
grazing land soil, mg/kg Ca, 3,019.7, 137,576.2
* based on measured CaO.

Based on the FOREGS dataset, the 95th percentile of 148.0 mg/L can be regarded as representative background concentration for dissolved calcium in European surface waters and the 95th percentile of 185,633.8 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 2.73 is derived.

Based on the FOREGS dataset, the 95th percentile of 161,391.5 mg/kg can be regarded as representative background concentration of calcium in topsoil of EU countries. Representative calcium concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 136,110.6 and 137,576.2 mg/kg, respectively, according to the GEMAS dataset.

Cross-reference 3

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 5^th, 50^th and 95^th 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 5^th, 50^th and 95^th 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 95^th percentile of 8.7 mg/L can be regarded as representative background concentration for dissolved silicon in European surface waters and the 95^th 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 K_p 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.	5^thP	50^thP
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	SO4^2-	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

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

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

³ Removal of 2 outliers < 0.01.

⁴ 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 5^th, 50^th and 95^th 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 95^th 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.	5^thP	50^thP	95^thP
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 5^th, 50^th and 95^th 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 5^th, 50^th and 95^th 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.	5^th P	50^th P	95^th 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.	5^thP	50^thP	95^thP
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.

Cross-reference 4

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), information on ambient water levels was retrieved from the monitoring-based exercise under the EU Water Framework Directive as reported by Carvalho et al. (2016) and the European Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS), with respect to tin 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 tin 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. Since a significant number of the FOREGS stream water samples of tin were contaminated prior to analysis, stream water data for tin have been rejected and are not available from the FOREGS dataset.

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.
- The FOREGS team rejected the stream water data for tin since a significant number of samples were contaminated during sampling and storage. Nevertheless, other water parameters (including pH, hardness and organic carbon concentrations) were measured.
- A total of 795 stream water samples and 839 sediment samples were processed in the FOREGS-program, including 745 paired samples, i.e. samples with the same coordinates for the sampling location of stream sediment and corresponding stream water parameters..
- The FOREGS dataset reports tin 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).
- 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.

Monitoring-based exercise under the EU Water Framework Directive (Carvalho et al. 2016):
- Monitoring data were collected from different databases for the whole-water and/or dissolved fraction of twenty five metals in inland waters, including data for the whole-water fraction of tin.
- The following data sources were used: SoE - Database containing monitoring data reported by European countries under the State of the Environment (SoE) WISE (Water Information System for Europe) managed by the European Environment Agency; MSDAT - Data directly submitted to the JRC by EU member states following a request of DG ENV to the EU Water Directors (on 21.03.2014). In addition, some monitoring data have been submitted on behalf of European drinking water companies.; EMPODAT - Database of geo-referenced monitoring data managed by NORMAN (Network of reference laboratories, research centres and related organisations for monitoring of emerging environmental substances); JDS - Monitoring data from the third Joint Danube Survey from 2013; IPCheM - Information Platform for Chemical Monitoring data, managed by JRC downloaded in 01/2015.
- Monitoring data for tin in inland waters consisted of measured total (not dissolved) concentrations of 12,807 samples from 1,132 different sites in 9 countries, including non-quantified concentrations set to ½ LOD/Q.

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 tin 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.

- Since a significant number of tin samples were contaminated prior to analysis, stream water data for tin have been rejected and are not available. Nevertheless, a global average concentration of less than 0.01 µg/L was reported for stream water. In United Kingdom river water, concentration of tin is typically less than 0.5 µg/L (Salminen et al. 2005 and references therein).

- This seems to be in agreement with information collected by Carvalho et al. 2016 for the monitoring-based exercise under the EU Water Framework Directive. Total tin concentrations of inland waters from 1,132 different sites in 9 countries range from 0.01 to 224.0 µg/L with 50^th and 95^th percentiles of 0.5 and 25.0 µg/L, respectively.

- In the FOREGS dataset, tin concentrations in the sediment range from < 1.0 (< LOQ) to 188.0 mg/kg with 5^th, 50^th and 95^th percentiles of < 1.0 (< LOQ), 2.2 and 14.0 mg/kg, respectively (Table 1).

- Taking into account the high quality and representativeness of the FOREGS data set, the 95^th percentile of 14.0 mg/kg can be regarded as representative background concentration of tin in European stream sediments. The 95^th percentile of 25.0 µg/L reported by Carvalho et al. 2016 can be regarded as estimate for a representative ambient concentration of measured total (not dissolved) tin in European surface waters.

Table 1: Water parameters and tin concentrations of stream sediment.

	Parameter	#	Unit	Min.	Max.	5^thP	50^thP	95^thP
water	pH ^1	737 ^2	-	9.80	4.50	8.50	7.70	6.10
water	Ca	745	mg/L	0.23	592.00	1.64	42.70	148.00
water	Cl	745	mg/L	0.14	4,560.00	0.49	9.40	71.19
water	HCO3	743 ^3	mg/L	0.69	1,804.42	5.38	131.37	373.60
water	K	745	mg/L	< 0.01	182.00	0.15	1.65	9.85
water	Mg	745	mg/L	0.05	230.00	0.46	6.24	38.63
water	Na	745	mg/L	0.23	4,030.00	1.00	6.76	48.34
water	NO3	745	mg/L	< 0.04	107.00	< 0.04	3.10	39.86
water	DOC	743 ^4	mg/L	< 0.50	57.94	0.60	4.79	23.04
water	SO4^2-	745	mg/L	< 0.30	2,420.00	1.18	17.10	166.99
sediment	Sn	745	mg/kg	< 1.00	188.00	< 1.00	2.20	14.00

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

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

³ Removal of 2 outliers < 0.01.

⁴ 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 tin levels in topsoil range from < 1.0 (< LOQ) to 106.0 mg/kg with 5^th, 50^th and 95^th percentiles of 1.0 (< LOQ), 3.0 and 10.0 mg/kg, respectively (see Table 2).

- Taking into account the high quality and representativeness of the data set, the 95^th percentile of 10.0 mg/kg can be regarded as representative background concentration of tin in topsoil of EU countries.

Table 2: Concentrations of tin in topsoil samples.

Parameter	Unit	#	Min.	Max.	5^thP	50^thP	95^thP
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
Sn	mg/kg	833	< 2.00	106.00	< 2.00	3.00	10.00

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

GEMAS DATABASE AGRICULTURAL AND GRAZING LAND SOIL CONCENTRATIONS:

- Tin levels of agricultural soil range from < 0.1 (< LOQ) to 30.4 mg/kg with 5^th, 50^th and 95^th percentiles of 0.2, 0.8 and 2.5 mg/kg, respectively (see Table 3). In grazing land, soil concentrations of tin range from < 0.1 (< LOQ) to 158.3 mg/kg with 5^th, 50^th and 95^th percentiles of 0.3, 0.9 and 2.8 mg/kg, respectively (see Table 4).

Table 3: Agricultural soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^th P	50^th P	95^th 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
Tin	mg/kg	AR	1,867	< 0.10	30.43	0.24	0.75	2.51
Tin	mg/kg	XRF	1,867	< 4.00	129.00	< 4.00	< 4.00	6.00
Tin	mg/kg	MMI	1,867	< 0.001	0.03	< 0.001	< 0.001	0.005

Table 4: Grazing land soil concentrations.

Parameter	Unit	Method	#	Min.	Max.	5^thP	50^thP	95^thP
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
Tin	mg/kg	AR	1,781	0.05	158.27	0.27	0.85	2.78
Tin	mg/kg	XRF	1,781	2.00	809.00	2.00	2.00	6.00

Conclusions:

Representative background or ambient concentrations of tin in environmental compartments are tabulated below.

compartment, unit, concentration (50th P), concentration (95th P)
background water *, µg/L Sn, 0.5, 25.0
background stream water sediment, mg/kg Sn, 2.2, 14.0
background topsoil, mg/kg Sn, 3.0, 10.0
agricultural soil, mg/kg Sn, 0.8, 2.5
grazing land soil, mg/kg Sn, 0.9, 2.8
* based on Carvalho et al. 2016.

Based on Carvalho et al. 2016, the 95th percentile of 25.0 µg/L can be regarded as estimate for a representative ambient total tin concentration of European inland waters whereas based on the FOREGS dataset, the 95th percentile of 14.0 mg/kg can be regarded as representative background concentration of European stream sediments.

Based on the FOREGS dataset, the 95th percentile of 10.0 mg/kg can be regarded as representative background concentration of tin in topsoil of EU countries. Representative tin concentrations (95th percentile) of agricultural and grazing land soil (i.e. ambient levels) amount to 2.5 and 2.8 mg/kg, respectively, according to the GEMAS dataset.