Spinels, cobalt tin grey

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics, other

Remarks:

Bioaccessibility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-04-17 to 2015-07-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Objective of study:

bioaccessibility (or bioavailability)

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

yes

Remarks:

Bioaccessibility testing: loading of 100 mg/L; five artificial physiological media agitated at 100 rpm, at 37 °C ± 2 °C; sampling after 2 h and 24 h; determination of Co and Sn concentrations after filtration by ICP-OES and ICP-MS.

Principles of method if other than guideline:

The test was performed on the basis of OECD Series on Testing and Assessment No. 29 as well as according to the bioaccessibility test protocol provided by the monitor. The bioaccessibility protocol has been developed on the basis of relevant published methods ([1], [2], [3], [4] and [5]).

The aim of this test was to assess the dissolution of the pigment IPC-2018-009 (cobalt magnesium tin spinel) in the artificial physiological media GST, GMB, ALF, ASW and PBS. The test media were selected to simulate relevant human-chemical interactions (as far as practical), i.e. a substance entering the human body by ingestion or by inhalation.

Five different artificial physiological media with a single loading of test substance of 100 mg/Lwere used. The measurement of dissolved cobalt and tin concentrations after filtration were performed by ICP-OES and ICP-MS. Samples were taken after 2 and 24 hours agitation (100 rpm) at 37 ± 2 °C. The study was performed in triplicate with two additional method blanks per medium.

[1] Hanawa T. 2004. Metal ion release from metal implants. Materials Science and Engineering C 24: 745-752.
[2] Stopford W., Turner J., Cappelini D., Brock T. 2004. Bioaccessibility testing of cobalt compounds. Journal of Environmental Monitoring 5: 675-680.
[3] Midander K., et al. 2007. In vitro studies of copper release from powder particles in synthetic biological media. Environmental Pollution 145: 51-59.
[4] European standard 1998. Test method for release of nickel from products intended to come into direct and prolonged contact with the skin (EN 1811)
[5] ASTM 2003. Standard test method for determining extractability of metals from art materials. ASTM D5517-03.

GLP compliance:

yes (incl. QA statement)

Remarks:

, signed 2016-05-31

Test material

Test material information

Constituent 1

Reference substance name:

Cobalt magnesium tin spinel

Cas Number:

68187-05-3

Molecular formula:

Mg(2-x)Co(x)SnO4 0,2≤x≤0,75

IUPAC Name:

Cobalt magnesium tin spinel

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material: Cobalt tin grey spinel
- new EC name: Cobalt magnesium tin spinel
- Physical state: odourless, blue powder
- Structure: spinel
- Storage condition of test material: Kept dry in closed containers

Test animals

Species:

other: in vitro (simulated human body fluids)

Details on test animals or test system and environmental conditions:

Test principle in brief:
- five different artificial physiological media,
- single loading of test substance of 100 mg/L,
- samples taken after 2 and 24 hours agitation (100 rpm) at 37 ± 2 °C,
- two method blanks per artificial media were tested; measurement (by ICP-OES and IPC-MS) of dissolved cobalt and tin concentrations after filtration
- the study was performed in triplicate

The aim of this test was to assess the dissolution of IPC-2018-009 (cobalt magnesium tin spinel) in five artificial physiological media: Artificial lysosomal fluid (ALF, pH = 4.5), Artificial sweat solution (ASW, pH = 6.5), Gamble´s solution (GMB, pH = 7.4), Artificial gastric fluid (GST, pH = 1.5), Phosphate buffered saline (PBS, pH = 7.4). The test media were selected to simulate relevant human-chemical interactions (as far as practical), i.e. a substance entering the human body by ingestion into the gastrointestinal tract and by inhalation.

Administration / exposure

Duration and frequency of treatment / exposure:

Samples were taken after 2 h and 24h.

Doses / concentrations

Dose / conc.:

100 other: mg of the test item /L artifical media

Details on study design:

Reagents
The water (resistivity >18 MΩ·cm.) used for this test was purified with a Pure Lab Ultra water purification system from ELGA LabWater, Celle, Germany.
- Nitric acid - “Supra” quality (ROTIPURAN® supplied by Roth, Karlsruhe, Germany).
- Hydrochloric acid – “instra-analyzed plus” quality (J.T. Baker, Griesheim, Germany).
- Sodiumhydroxide – pro Analysis quality (Chemsolute, Th. Geyer, Renningen, Germany)

Metal analysis
- Standards: Merck Certipur Cobalt ICP standard 1000 mg/L lot no. HC41722713; Merck Certipur Tin ICP standard 1000 mg/L lot no. HC375770; Darmstadt, Germany).
- Certified reference materials: quality control standards TM-25.4 (lot no. 0914) and TMDA-53.3 (lot no. 0914) obtained from Environment Canada and multielement standards (Merck XVII, lot no. HC382226 – only tin; Merck XXI, lot no. HC42984673 – only cobalt , Darmstadt, Germany) were analyzed for total dissolved tin and cobalt by ICP-MS and ICP-OES along with the samples to determine the accuracy of the applied analytical method. Furthermore the calibration solutions were measured along with the ICP-MS and ICP-OES measurements as recalibration standards.

Instrumental and analytical set-up for the ICP-OES instrument:
Agilent 720, Agilent Technologies, Waldbronn, Germany
Nebulizer: Sea spray nebulizer from Agilent
Spray chamber: Glass cyclonic spray chamber from Agilent
Carrier gas flow: 0.75 L/min
RF power: 1200W
Wavelengths: Co: 201.151 nm, 230.786 nm, 231.406 nm, 235.341 nm, 237.863 nm, 238.345 nm, 238.636 nm, 238.892 nm and 258.033 nm;
Sn: 183.113 nm, 189.925 nm, 215.152 nm, 224.606 nm, 242.170 nm, 242.950 nm and 326.233 nm

The applied LOD/LOQ calculations for the Agilent 720 ICP-OES are (according to DIN 32645):
LOD: 3 x standard deviation of calibration blank/slope of the calibration
LOQ: 3 x LOD

Calibration: blank, 1 µg/L, 2.5 µg/l, 5 µg/L, 7.5 µg/L, 10 µg/L, 25 µg/L, 50 µg/L, 75 µg/L, 100 µg/L, 250 µg/L, 500 µg/L, 750 µg/L and 1000 µg/L.
Correlation coefficients (r): at least 0.999832

Determination of mass balance
To the residual, undissolved test item in the vessels, 80 mL aqua regia (3 : 1 mixture of concentrated hydrochloric and nitric acid) were added to the flasks after the test. The filters used for sampling were extensively rinsed with aqua regia. Solutions were sampled after at least 24h, chromium, cobalt and zinc concentration were measured in at least one mass balance sample (vessel and filter/syringes) for each medium by ICP-OES, and the mass balance was calculated.

Instrumental and analytical set-up for the ICP-MS instrument:
Agilent 7700ce ICP-MS, Agilent Technologies, Waldbronn Germany
Nebulizer: Conical nebulizer, from Glass Expansion
Spray chamber: Scott Type spray chamber, from Agilent
Carrier gas flow: 0.93 L/min
Dilution Gas flow: 0.1 – 0.16 L/min
RF power: 1500 W
Isotopes: 59Co, 118Sn, 119Sn, 120Sn and 103Rh (internal standard)

The applied LOD/LOQs were calculated as follows:
LOD: 3 x standard deviation of calibration blank divided by the slope of calibration line;
LOQ: 3 x LOD.
The data for the LODs were read directly from the Agilent 7700 ICP-MS instrument output (data calculated by internal algorithms of the instrument software).

Calibration:blank, 0.1 µg/L, 0.25 µg/l, 0.5 µg/L, 0.75 µg/L, 1 µg/L, 2.5 µg/L, 5.0 µg/L, 7.5 µg/L, 10 µg/L, 12.5 µg/L, 15 µg/L, 17.5 µg/L, 20 µg/L, 22.5 µg/L, 25 µg/L, 50 µg/L, 75 µg/l and 100 µg/L
Correlation factors (r): at least 0.999830

Details on dosing and sampling:

Loading:
Detailed loadings of the test vessels are given in "Any other information on materials and methods incl. tables".

Results and discussion

Toxicokinetic / pharmacokinetic studies

Toxicokinetic parameters

Toxicokinetic parameters:

other: bioaccessibility

Remarks:

Dissolution of Co at a loading of 0.1 g/L: ALF 24h: 6235 ± 71.3 μg/L. Dissolution of Sn at a loading of 0.1 g/L: ALF 24h: 45205 ± 278 μg/L

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:

Concentration of dissolved cobalt in artificial physiological media
Total Co ± SD in sample vessels
- GST 2h: 151 ± 16.5 μg/L
- GST 24h: 3979 ± 38.4 μg/L
- GMB 2h: 0.485 ± 0.047 μg/L
- GMB 24h: 1.06 ± 0.03 μg/L
- ALF 2h: 501 ± 79.7 μg/L
- ALF 24h: 6235 ± 71.3 μg/L
- ASW 2h: 6.43 ± 0.11 µg/L
- ASW 24h: 123 ± 2.45 µg/L
- PBS 2h: 0.509 ± 0.143 μg/L
- PBS 24h: 6.90 ± 0.73 μg/L

Concentration of dissolved tin in artificial physiological media
Total tin ± SD in sample vessels
- GST 2h: 208 ± 32.6 μg/L
- GST 24h: 10.5 ± 3.61 μg/L
- GMB 2h: 1.42 ± 0.47 μg/L
- GMB 24h: All samples below LOD
- ALF 2h: 3560 ± 567 μg/L
- ALF 24h: 45205 ± 278 μg/L
- ASW 2h: 54.5 ± 5.40 μg/L
- ASW 24h: 626 ± 11.8 μg/L
- PBS 2h*: 3.89 ± 1.21 μg/L
- PBS 24h*: 29.3 ± 7.11 μg/L

Any other information on results incl. tables

Method validation summary ICP-MS

validation parameter	results	Comment
Selectivity	similar data with two different gas modes or two different Isotopes and same gas mode	-
Linearity	applied calibration functions were linear	correlation coefficient at least 0.999830
Limit of detection	Co: 0.001 – 0.023 µg/L Sn: 0.004 – 0.223 µg/L
Limit of quantification	Co: 0.004 – 0.070 µg/L Sn: 0.012 – 0.669 µg/L
Accuracy measurement / Reproducibility	Mean recovery for CRM TM-25.4 (dilution factor 5): Co: 101 ± 3.6 % (n = 14) Sn: 104 ± 2.9 % (n = 19)	Low concentration range (certified with 27.5 µg Co/L - diluted 5.50 µg Co/L; 23.8 µg Sn/L – diluted 4.76 µg/L)
Trueness test samples	Quality control standard Merck XVII: Sn: 93.6 ± 6.4 % (n = 17)	Mid concentration range (20 µg/L)
Trueness test samples	Quality control standard Merck XXI: Co: 97.7 ± 3.9 % (n = 14)	High concentration range (20 µg/L)
Trueness test samples	Recalibration standard: Co: 96.9 ± 5.6 % (n = 14) Sn: 100 ± 3.0 % (n = 16)	Low concentration range (5 µg/L)
Trueness test samples	Recalibration standard: Sn: 101 ± 1.2 % (n = 3)	Mid concentration range (10 µg/L)
Trueness test samples	Recalibration standard: Sn: 101 ± 1.2 % (n = 3)	High concentration range (50 µg/L)
Trueness test samples/mass balance samples	Fortification of samples: Co: 90.2 – 98.4 % Sn: 91.1 – 101 %

Cobalt and tin concentration in method blanks

Artificial media	Co	Sn
GST	All method blanks below LOD	All method blanks below LOD
GMB	All method blanks below LOD/LOQ	All method blanks below LOD
PBS	Two method blanks 2h below LOD, one method blank below LOQ, one method blank above LOQ: 2hà0.004 ± 0.002 µg/L; 2h method blanks at least 147 fold lower than samples; 24h all method blanks below LOD	All method blanks below LOD/LOQ

Fortification

For fortified test samples, recoveries were in the range of 90.2 – 98.4 % for Co and 91.1 – 101 % for Sn.

Fortification of Co in test samples

sample	measured concentration [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
GMB vessel 1 sample a 2h	0.520	0.430	0.423 / 98.3
GMB vessel 2 sample a 24h	1.12	2.41	2.37 / 98.4
PBS vessel a sample a 2h	0.603	0.368	0.332 / 90.2
PBS vessel a sample a 24h	7.61	3.20	2.95 / 92.1

Fortification of Sn in test samples

sample	measured concentration [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
GST vessel 1 sample a 2h (dilution factor 20)	11.1	12.4	12.3 / 98.9
GST vessel 1 sample a 24h (dilution factor 2)	3.88	5.08	5.03 / 98.9
GMB vessel 1 sample a 2h	1.78	1.27	1.21 / 95.6
GMB vessel 2 sample a 24h	<LOD^#	1.67	1.52 / 91.1
PBS vessel a sample a 2h	5.02	1.84	1.85 / 101
PBS vessel 1 sample b 24h	37.7	50.1	50.8 / 101

^#Solutions with concentrations below the LOD/LOQ were also fortified. However, a recovery of ± 15 % may not be realistic as concentrations in the original (unfortified) sample below the LOD may be lower than the noise ratio and concentrations below the LOQ are between the noise ratio and a real (quantifiable) signal. For solutions with concentrations below the LOD/LOQ, a recovery of ± 25 % - 30 % is more realistic.

Method validation summary ICP-OES

validation parameter	results	Comment
Selectivity	similar data with different wavelengths for ICP-OES method	-
Linearity	applied calibration functions were linear	coefficient at least 0.999832
Limit of detection	Co: 0.088 – 0.532 µg/L Sn: 2.23 – 3.93 µg/L
Limit of quantification	Co: 0.265 – 1.59 µg/L Sn: 6.69 – 11.8 µg/L
Method blanks	Co: in all samples below LOD in ASW and ALF Sn: in all samples below LOD in ASW and ALF	-
Accuracy measurement / Reproducibility testsamples	Mean recovery for CRM TM-25.4 (dilution factor 2): Co: 101 ± 1.8 % (n = 2)	Mid concentration range (certified with 27.5 µg Co/L, diluted 13.75 µg Co/L)
Accuracy measurement / Reproducibility testand mass balance measurements	Mean recovery for CRM TM-25.4 (dilution factor 5): Co: 106 ± 3.8 % (n = 10) Sn: 97.1 ± 10 % (n = 7)	Low concentration range (certified with 27.5 µg Co/L, diluted 5.50 µg Co/L; 23.8 µg Sn/L, diluted 4.76 µg Sn/L)
Accuracy measurement / Reproducibility testsamples	Mean recovery for CRM TMDA-53.3 (dilution factor 10): Co: 102 ± 2.1 % (n = 2)	Mid concentration range (certified with 252µg Co/L, diluted 25.2 µg Co/L)
Truenesstest sample measurements	Quality control standard (Merck XXI): Co: 101 ± 1.4 % (n = 2)	Mid concentration range (50 µg/L)
Truenesstestand mass balance measurements	Quality control standard (Merck XVII): Sn: 96.2 ± 2.5 % (n = 11)	Mid concentration range (100 µg/L)
Truenesstestand mass balance measurements	Quality control standard (Merck XVII): Sn: 101 ± 3.6 % (n = 11)	High concentration range (500 µg/L)
Truenesstestand mass balance measurements	Quality control standard (Merck XXI): Co: 99.0 ± 1.9 % (n = 11)	Mid concentration range (100 µg/L)
Truenesstestand mass balance measurements	Quality control standard (Merck XXI): Co: 97.6 ± 1.3 % (n = 10)	High concentration range (500 µg/L)
Truenesstest sample measurements	Recalibration standard Co: 98.1 ± 0.1 % (n = 2)	Low concentration range (10 µg/L)
Truenesstestsample and mass balance measurements	Recalibration standard Co: 98.5 ± 1.7 % (n = 11) Sn: 96.8 ± 3.3 % (n = 11)	Mid concentration range (50 µg/L)
Truenesstestsample and mass balance measurements	Recalibration standard Co: 99.9 ± 1.6 % (n = 10) Sn: 98.7 ± 2.4 % (n = 10)	High concentration range (250 µg/L)
Truenesstest sample measurements	Recalibration standard Co: 99.3 % (n = 1) Sn: 98.9 % (n = 1)	High concentration range (500 µg/L)
Trueness test samples and mass balancesample measurements	Fortification of samples: Co: 96.5 - 101 % Sn: 97.2 – 101 %

Fortification

From selected artificial physiological media, samples were fortified with a known amount of cobalt and tin (by standard addition of commercial standards) to determine the standard recovery.

For fortified test samples, recoveries were in the range of 96.5 – 101 % for Co and the recoveries of Sn were in the range of 97.2 – 101 % in test samples.

Fortification of test samples with cobalt

sample	measured concentration of Co [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
GST vessel 1 sample a 2h (dilution factor 10)	16.6	29.9	30.3 / 101
GST vessel 1 sample a 24h (dilution factor 100)	40.7	54.4	54.7 / 101
ASW vessel 1 sample b 2h	6.49	33.9	33.5 / 98.7
ASW vessel 1 sample b 24h (dilution factor 2)	62.7	238	235 / 98.7
ALF vessel 1 sample a 2h (dilution factor 10)	41.1	54.7	53.1 / 97.2
ALF vessel 1 sample a 24h (dilution factor 100)	63.9	68.3	65.9 / 96.5
ALF vessel 1 mass balance (dilution factor 100)	55.7	63.4	62.0 / 97.8
ASW vessel 3 mass balance (dilution factor 100)	63.1	77.8	76.6 / 98.4
GMB vessel 3 mass balance (dilution factor 100)	61.6	137	133 / 97.3
GST vessel 1 mass balance (dilution factor 100)	57.1	74.3	73.8 / 99.4
PBS vessel 1 mass balance (dilution factor 100)	33.2	39.9	39.0 / 97.6

Fortification of test samples with tin

sample	measured concentration of Sn [µg/L]	calculated level after addition [µg/L]	recovery [µg/L] / [%]
ASW vessel 1 sample b 2h	57.1	64.2	63.8 / 99.3
ASW vessel 1 sample b 24h (dilution factor 2)	323	394	385 / 97.9
ALF vessel 2 sample a 2h (dilution factor 10)	408	445	439 / 98.6
ALF vessel 1 sample a 24h (dilution factor 100)	460	306	298 / 97.2
ALF vessel 1 mass balance (dilution factor 100)	380	258	259 / 100
ASW vessel 3 mass balance (dilution factor 100)	429	297	296 / 99.4
GMB vessel 3 mass balance (dilution factor 100)	422	353	349 / 98.9
GST vessel 1 mass balance (dilution factor 100)	148	129	130 / 101
PBS vessel 1 mass balance (dilution factor 100)	228	157	155 / 98.5

Solution pH values

During the study, the pH of GST, ALF and PBS media remained stable in the method blank vessels and the test vessels. A low increase of the pH for GST was measurable but this was measurable for the method blanks, too. Therefore, a possible effect of the test substance can be excluded.

In GMB medium, the pH in all vessels (including method blanks) increased during the time of the test from 7.40 to 8.87, 8.88 and 8.96 (test vessels) and 7.40 to 8.88 and 8.94 (method blank vessels). Therefore, an effect of the test substance can be excluded. In fact, the pH of the GMB media does not seem to be stable under the conditions of the test.

In ASW medium, the pH in all vessels (including method blanks) decreased during the time of the test from 6.50 to 6.15 and 6.16 (test vessels) and 6.50 to 5.93 and 5.95 (method blank vessels). Therefore, an effect of the test substance can be excluded.

Temperature control

The temperature was adjusted to 37.5 in a thermostatically controlled shaking cabinet to reach a temperature of 37 ± 2 °C in the media. The temperature in thermostatically controlled shaking cabinet was confirmed by a certified thermometer and a thermo data logger. In all test vessels, the temperature was constant at 37 ± 2 °C.

Mass balance calculation

For the mass balance dissolved cobalt and tin concentrations in vessels and filters as measured by ICP-OES indicate mainly a complete dissolution of IPC-2018-009 in the physiological media after addition of aqua regia to the sample vessels. Due to the observations during the mass balance less amount of test item was still visible which could be a result of insoluble parts of the test item.

Amount of cobalt in mass balance samples (vessels, filter/syringes and taken samples) for each media for one vessel each

media	value for dissolved Co after addition of aqua regia		In samples [mg]	Calculated value Co [mg]*	nominal amount [mg]#	recovery [%]
	Vessels [mg]	Filters/syringes [mg]
GST vessel 1	2.86	0.002	0.168	3.03	3.28	92.4
GMB vessel 3	3.08	0.00004	0.0001	3.08	3.29	93.5
ALF vessel 1	2.79	0.001	0.270	3.06	3.27	93.6
ASW vessel 2	3.22	0.00004	0.005	3.23	3.31	97.3
PBS vessel 3	1.63	0.0003	0.00001	1.63	3.28	49.7

* Measured dissolved Co includes the amount of tin in test solutions after addition of aqua regia, the amount of tin rinsed of used filters and syringe and the amount of tin removed with samples during the study.

Example ALF: 2.79 mg (amount Co in vessel) + 0.001 mg (amount Co in syringe/filters) + 0.270 mg (Co in samples) = 3.06 mg

# nominal amount Co = 6.50 % in test item (according to CoA) -> 3.25 mg Co in 50 mg test item -> nominal amount 3.25 mg * initial weight mg / 50 mg

Example: 3.25 mg Co * 50.264 mg test item / 50 mg = 3.27 mg Co

Applicant's summary and conclusion

Conclusions:

On the basis of OECD Series on Testing and Assessment No. 29 as well as according to a bioaccessibility test protocol, which has been developed on the basis of relevant published methods, the dissolution of the pigment cobalt magnesium tin spinel in artificial physiological media with a single loading of 100 mg/L at 37 °C ± 2 °C was determined.

Concentration of dissolved cobalt in artificial physiological media
Total Co ± SD in sample vessels
- GST 2h: 151 ± 16.5 µg/L
- GMB 2h: 0.485 ± 0.047 µg/L
- ALF 2h: 501 ± 79.7 µg/L
- ASW 2h: 6.43 ± 0.11 µg/L
- PBS 2h: 0.512 ± 0.143 µg/

- GST 24h: 3979 ± 38.4 μg/L
- GMB 24h: 1.06 ± 0.03 μg/L
- ALF 24h: 6235 ± 71.3 μg/L
- ASW 24h: 123 ± 2.45 µg/L
- PBS 24h: 6.90 ± 0.73 μg/L

Concentration of dissolved tin in artificial physiological media
Total tin ± SD in sample vessels (corrected concentrations, corresponding to a loading of exactly 100 mg/L) without method blank subtraction (all method blanks below LOD(*/LOQ))
- GST 2h: 208 ± 32.6 µg/L
- GMB 2h: 1.42 ± 0.47 µg/L
- ALF 2h: 3560 ± 567 µg/L
- ASW 2h: 54.5 ± 5.40 µg/L
- PBS 2h: 3.89 ± 1.21 µg/L

- GST 24h: 10.5 ± 3.61 μg/L
- GMB 24h: All samples below LOD
- ALF 24h: 45205 ± 278 μg/L
- ASW 24h: 626 ± 11.8 μg/L
- PBS 24h: 29.3 ± 7.11 μg/L