Zirconium vanadium blue zircon

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Objective of study:

bioaccessibility (or bioavailability)

Principles of method if other than guideline:

An internationally agreed guideline does not exist for this test (e.g. OECD). However, similar tests have been conducted with several metal compounds, including steels, in previous risk assessments (completed under Regulation (EEC) No 793/93) and in recent preparation for REACH regulation (EC) No 1907/2006.
The test was performed on the basis of the guidance for OECD-Series on testing and assessment Number 29 and according to the bioaccessibility test protocol provided by the study monitor.

GLP compliance:

yes (incl. QA statement)

Remarks:

2011-02-07

Test material

Test material information

Constituent 1

Reference substance name:

Zirconium vanadium blue zircon

EC Number:

269-057-9

EC Name:

Zirconium vanadium blue zircon

Cas Number:

68186-95-8

Molecular formula:

(Zr, V)SiO4

IUPAC Name:

silicon(4+) vanadium(4+) zirconium(4+) hexaoxidandiide

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Substance name: Zirconium vanadium blue zircon
Appearance: solid, light blue powder, odourless

Test animals

Species:

other: in vitro (simulated human body fluids)

Details on test animals or test system and environmental conditions:

For the experimental setup the test item was weighed into flasks, put to volume with the respective artificial physiological medium (loading of approx. 100 mg/L) and agitated at 100 rpm at 37°C ± 2°C. Samples were taken after 2h and 24h. The total dissolved zirconium and vanadium concentrations in samples were determined after filtration (0.2 µm, Supor membrane) by ICP-MS.

Administration / exposure

Details on dosing and sampling:

For the experimental setup the test item was weighed into flasks, put to volume with the respective artificial physiological medium (loading of approx. 100 mg/L) and agitated at 100 rpm at 37°C ± 2°C. Samples were taken after 2h and 24h. The total dissolved zirconium and vanadium concentrations in samples were determined after filtration (0.2 µm, Supor membrane) by ICP-MS.

Five different artificial physiological media, single loading of test substance of 100 mg/L, measurement of dissolved zirconium and vanadium concentrations after 2 and 24 hours agitation (100 rpm) at 37 ± 2°C, two additional method blanks per medium. The study was performed in duplicates.

Two additional control blanks (same procedure) were also prepared. Two replicates and two method blanks per artificial media were tested; solutions were sampled after 2 and 24h, to measure total dissolved zirconium and vanadium concentrations (by ICP-MS), temperature and pH.

Solutions were sampled for measuring total dissolved zirconium and vanadium by ICP-MS. All samples were filtered through 0.2 µm filter (Syringe Filter w / 0.2 µm, polyethersulfon membrane, DIA Nielsen, Dueren, Germany) prior to further treatment.

Aqueous samples of approx. 20 mL taken for Zr and V analysis were transferred into disposable scintillation vials (20 mL scintillation tubes, Sarstedt, Nuembrecht, Germany), acidified (target conc. 3% HNO3) and stored at approx. 4°C until analysis.

The maximum storage time until measurement of the samples was less than four months. According to DIN EN ISO 5667-3: 2003 dissolved metals in aqueous samples (waste-, ground- and surface-water) are at least stable for six months. Furthermore, the analysed CRMs are stable under these conditions for at least one year from the date of shipment. Acidification is the stabilization method that is recommended in standard methods for metal analysis (e.g. ISO 11885, DIN).
Solution pH was measured directly in the test vessel.

Analysis of mass balance by ICP-OES:
Zirconium and vanadium concentrations of aqueous mass balance samples were measured using an IRIS Intrepid II ICP-OES (Thermo Electron, Dreieich, Germany). Zirconium was detected at the wavelength 339.198 nm. Vanadium was detected at the wavelengths 290.882 nm, 292.402 nm and 292.464 nm. Depending on concentrations of the samples, the following zirconium solutions were used to calibrate the instrument: blank, 5 µg/L, 10 µg/L, 25 µg/L, 50 µg/L, 100 µg/L, 200 µg/L, 300 µg/L and 400 µg/L. For the calibration, the following vanadium concentrations were used: blank, 5 µg/L, 10 µg/L, 25 µg/L, 50 µg/L, 100 µg/L, 200 µg/L, 300 µg/L and 400 µg/L. Calibrations were performed before each measurement. The calibration formula was calculated using the linear regression algorithm of the ICP-OES instrument software. The respective wavelength data with the best correlation for the calibration in the measurements were used for calculating concentrations (i.e. 292.464 nm for vanadium). Correlation coefficients (r) were at least 0.9997. For each sample, at least three internal measurements were performed and the mean was calculated and printed by the instrument software.
Instrumental and analytical set-up for the ICP-OES instrument:
Thermo IRIS Intrepid II from Thermo Electron Corporation, Germany
Nebulizer: Concentric glass nebulizer, from Thermo
Spray chamber: Glass cyclonic spray chamber, from Thermo
Nebulizer gas flow: 0.68 L/min
Make-up gas flow: 0.5 L/min
RF power: 1150 W

Wavelengths: Zr: 339.198 nm; V 290.882 nm, 292.402 nm and 292.464 nm

Two measurements were performed for the determination of zirconium and vanadium concentrations in the mass balance samples and filter samples.
The applied LOD/LOQ calculations are:

LOD: 3 * method standard deviation from calibration line;
LOQ: 10 * method standard deviation from calibration line.
These data were read directly from the Thermo IRIS Intrepid II ICP-OES instrument output (data calculated by internal algorithms of the instrument software). A representative calibration line is shown in the raw data.

Analysis of total dissolved Zr and V concentrations by ICP-MS:
The analysis of total dissolved zirconium and vanadium in medium samples was performed using an Agilent 7700 ICP-MS with collision cell (Agilent, Waldbronn, Germany). Zirconium was quantified by measuring the isotopes 90Zr and 91Zr and vanadium by measuring 51V. Depending on the concentration range of the samples, the following standard solutions were used for the calibrations: blank, 0.1 µg/L, 0.25 µg/L, 0.5 µg/L, 0.75 µg/L, 1.0 µg/L, 2.5 µg/L, 5.0 µg/L, 7.5 µg/L, 10.0 µg/L, 25.0 µg/L, 50.0 µg/L, 75.0 µg/L, 100 µg/L, 250 µg/L and 500 µg/L. A respective concentration range was selected for calibration to obtain a working range that covers zirconium and vanadium concentrations in samples.
The calibration formula was calculated using the linear regression algorithm of the ICP-MS instrument software. The respective isotope and measurement mode (noGas, Helium or HiHelium mode) for interference free measurement with the best recoveries for certified reference materials were used for calculating the respective test concentrations. Correlation factors (r) were at least 0.9974 in all measurement series. For each sample, at least three internal measurements were performed and the mean was calculated and printed by the instrument software.

Instrumental and analytical set-up for the ICP-MS instrument:
Agilent 7700 ICP-MS, Agilent Technologies, Waldbronn, Germany
Nebulizer: Concentric glass nebulizer, from GlassExpansion
Spray chamber: Scott Type spray chamber, from Agilent
Carrier gas flow: 0.91 L/min
Dilution/Make-up gas flow: 0.13 L/min
RF power: 1500 W
Isotopes: 51V, 90Zr, 91Zr, 103Rh (internal standard)

In sum, five series of measurements were performed for the determination of total dissolved zirconium and vanadium concentrations in samples including the test vessels as well as blanks to determine background levels of elements and fortified samples.
The LOD and LOQ for zirconium and vanadium were calculated using the internal instrument algorithm. This calculation is according to DIN 32645. For this the standard deviation of calibration blanks is multiplied by 3 and divided by the slope of the calibration line.

Results and discussion

Any other information on results incl. tables

Measured pH in method blank and test vessels inALF medium

sample name	target pH	pH prior to the test	temp. [°C] prior to the test	pH after 2h	temp.[°C]	pH after 24h	temp.[°C]
ALF vessel A	4.5	4.5	34.2	4.5	32.4	4.5	31.7
ALF vessel B	4.5	4.5	34.3	4.5	32.4	4.5	31.5
ALF blank vessel A	4.5	4.5	34.5	4.5	34.1	4.5	33.8
ALF blank vessel B	4.5	4.5	34.5	4.5	34.2	4.5	33.8

 

 

Measured pH in method blank and test vessels in ASW medium:

sample name	target pH	pH prior to the test	temp. [°C] prior to the test	pH after 2h	temp.[°C]	pH after 24h	temp.[°C]
ASW vessel A	6.5	6.5	35.0	6.5	34.2	7.6	33.9
ASW vessel B	6.5	6.5	34.7	6.5	33.7	7.6	33.6
ASW blank vessel A	6.5	6.5	35.0	6.5	35.4	6.4	35.4
ASW blank vessel B	6.5	6.5	35.2	6.5	35.4	6.4	35.6

 

Measured pH in method blank and test vessels in GMB medium:

sample name	target pH	pH prior to the test	temp. [°C] prior to the test	pH after 2h	temp.[°C]	pH after 24h	temp.[°C]
GMB vessel A	7.4	7.4	34.7	7.5	33.7	7.6	33.0
GMB vessel B	7.4	7.4	34.5	7.5	33.3	7.6	32.8
GMB blank vessel A	7.4	7.4	35.2	7.5	35.0	7.6	34.9
GMB blank vessel B	7.4	7.4	34.7	7.5	35.1	7.6	35.0

 

 

Measured pH in method blank and test vessels in GST medium:

sample name	target pH	pH prior to the test	temp. [°C] prior to the test	pH after 2h	temp.[°C]	pH after 24h	temp.[°C]
GST vessel A	1.5 – 1.6	1.6	36.0	1.6	34.0	1.6	34.0
GST vessel B	1.5 – 1.6	1.5	35.8	1.6	33.8	1.6	33.8
GST blank vessel A	1.5 – 1.6	1.6	36.3	1.6	35.8	1.6	35.8
GST blank vessel B	1.5 – 1.6	1.6	36.1	1.5	35.8	1.5	36.1

 

 Measured pH in method blank and test vessels in PBS medium:

sample name	target pH	pH prior to the test	temp. [°C] prior to the test	pH after 2h	temp.[°C]	pH after 24h	temp.[°C]
PBS vessel A	7.2 - 7.4	7.3	35.9	7.3	33.9	7.3	34.2
PBS vessel B	7.2 - 7.4	7.3	35.8	7.3	33.8	7.3	34.0
PBS blank vessel A	7.2 - 7.4	7.3	36.0	7.3	35.8	7.3	35.8
PBS blank vessel B	7.2 - 7.4	7.3	35.9	7.3	35.7	7.3	36.1

Concentration of zirconium in artificial media, calculated nominal zirconium concentration and dissolved amount of zirconium:

media and sample	total Zr ± SD in method blanks [µg/L]	total Zr ±SD in sample vessels [µg/L]	Zr ± SD in sample vessels with blank subtraction [µg/L]	calculated nominal Zr concentration in [µg/L]#	dissolved amount Zr in artificial media [%] normalizedfor measured background in method blank
ALF 2h	<LOD	49.1 ± 3.81	49.1 ± 3.81	47329	0.10 ± 0.01
ALF 24h	<LOD	53.0 ± 3.60	53.0 ± 3.60	47329	0.11 ± 0.01
ASW 2h	0.15 ± 0.05	0.87 ± 0.75	0.72 ± 0.75	47943	0.001 ± 0.002
ASW 24h	0.10 ± <0.01	2.10 ± 1.32	1.99 ± 1.32	47943	0.004 ± 0.003
GMB 2h	<LOD/LOQ	<LOD/LOQ	<LOD/LOQ	47661	-
GMB 24h	0.18 ± 0.01	0.25 ± 0.04	0.07 ± 0.04	47661	0.0002 ± 0.0001
GST 2h	0.11 ± <0.01	59.6 ± 2.75	59.5 ± 2.75	47449	0.13 ± 0.01
GST 24h	0.11 ± <0.01	61.7 ± 5.12	61.6 ± 5.12	47449	0.13 ± 0.01
PBS 2h	<LOD	<LOD	<LOD	47984	-
PBS 24h	<LOD	0.19	0.19	47984	0.0004

#(initial weight (e.g. 50mg)*47.16§ (percentage zirconium in test item)/100)*2 (multiplication to calculate zirconium amount in one litre --> 100 mg/L) = nominal zirconium concentration in [mg/L]/1000 = nominal zirconium concentration in [µg/L]

§according to CoA 63.70% Zr as ZrO₂==> 74.03% zirconium in ZrO₂==> (63.70% * 74.03%)/100% = 47.16% Zr in test item

In five different artificial physiological media, between 0.10 and 0.13% of zirconium was dissolved from the test item IPC-2013-002 Zirconium vanadium blue zircon depending on solution parameters and test duration.

Concentration of vanadium in artificial media, calculated nominal vanadium concentration and dissolved amount of vanadium:

media and sample	total V ± SD in method blanks [µg/L]	total V ±SD in sample vessels [µg/L]	V ± SD in sample vessels with blank subtraction [µg/L]	calculated nominal V concentration in [µg/L]#	dissolved amount V in artificial media [%] normalizedfor measured background in method blank
ALF 2h	<LOD	73.8 ± 2.01	73.8 ± 2.01	1244	5.93 ± 0.16
ALF 24h	<LOD	78.8 ± 2.06	78.8 ± 2.06	1244	6.33 ± 0.17
ASW 2h	<LOD	12.3 ± 7.56	12.3 ± 7.56	1261	0.98 ± 0.60
ASW 24h	<LOD	45.0 ± 21.6	45.0 ± 21.6	1261	3.57 ± 1.71
GMB 2h	<LOD	3.98 ± 0.42	3.98 ± 0.42	1253	0.32 ± 0.03
GMB 24h	0.07 ± 0.02	10.7 ± 0.84	10.6 ± 0.84	1253	0.85 ± 0.07
GST 2h	<LOD	102 ± 2.32	102 ± 2.32	1248	8.21 ± 0.19
GST 24h	<LOD	109 ± 4.86	109 ± 4.86	1248	8.77 ± 0.39
PBS 2h	<LOD	5.51 ± 1.93	5.51 ± 1.93	1262	0.44 ± 0.15
PBS 24h	<LOD	11.9 ± 3.88	11.9 ± 3.88	1262	0.94 ± 0.31

#(initial weight (e.g. 50mg)*1.24§ (percentage vanadium in test item)/100)*2 (multiplication to get vanadium amount in one litre --> 100 mg/L) = nominal vanadium concentration in [mg/L]/1000 = nominal vanadium concentration in [µg/L]

§according to CoA 2.22% V as V₂O₅==> 56.0166% vanadium in V₂O₅==> (2.22% * 56.0166%)/100% = 1.24% V in test item

In five different artificial physiological media, between 0.32 and 8.77% of vanadium was dissolved from the test item IPC-2013-002 Zirconium vanadium blue zircon depending on solution parameters and test duration.

Applicant's summary and conclusion

Conclusions:

As dissolved Zr and V concentrations were below 61.6 µg/L and 109 µg/L respectively, even at the highest loading of 0.1g/L, referring to a solubility of 0.062 % and 0.11 %, the pigment is considered biologically inert.

Executive summary:

The bioaccessibility of zirconium vanadium blue zircon has been investigated experimentally in vitro by simulating dissolution under physiological conditions considered to mimic the most relevant exposure routes (oral, dermal and inhalation), as follows:

-Gamble’s solution (GMB, pH 7.4) which mimics the interstitial fluid within the deep lung under normal health conditions,

-phosphate-buffered saline (PBS, pH 7.2), which is a standard physiological solution that mimics the ionic strength of human blood serum,

- artificial sweat (ASW, pH 6.5) which simulates the hypoosmolar fluid, linked to hyponatraemia (loss of Na+ from blood), which is excreted from the body upon sweating,

-artificial lysosomal fluid (ALF, pH 4.5), which simulates intracellular conditions in lung cells occurring in conjunction with phagocytosis and represents relatively harsh conditions and

-artificial gastric fluid (GST, pH 1.5), which mimics the very harsh digestion milieu of high acidity in the stomach.

In five different artificial physiological media dissolved zirconium concentrations were between < LoD and 0.13 %, dissolved vanadium concentrations were between 0.32 and 8.77 % based on respective element contained in 100 mg pigment.

Therefore, zirconium vanadium blue zircon may reasonably be considered not bioaccessible.