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Administrative data

Endpoint:
additional toxicological information
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 June 2016 to 06 July 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Type of study / information:
dissolution and bioaccessibility of test item bismuth silicate
Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
other: Stopford W, Turner J, Cappelini D, Brock T 2003. Bioaccessibility testing of Cobalt compounds. Journal of Environmental Monitoring 5:675-680.
Deviations:
not applicable
Qualifier:
according to guideline
Guideline:
other: “Guidance for generating and reporting methods of analysis in support of residue data requirements for Annex II (part A, Section 4) and Annex III (part A, Section 5)
Version / remarks:
EEC guideline SANCO/3029/99 rev. 4 dated 11/07/00
Deviations:
not applicable
Principles of method if other than guideline:
The dissolution and bioaccessibility of test item bismuth silicate was conducted in five physiological media: phosphate-buffered saline (PBS) (pH 7.2), artificial interstitial fluid or Gamble’s solution (pH 7.4), artificial sweat solution (pH 6.5), artificial lysosomal fluid (pH 4.5) and artificial gastric fluid (pH 1.5), selected to simulate relevant human-chemical interactions. The dissolved amount of the test item was quantified by the mass concentration of bismuth.
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrabismuth triorthosilicate
Cas Number:
14708-87-3
Molecular formula:
Bi . 3/4H4O4Si
IUPAC Name:
Tetrabismuth triorthosilicate
Test material form:
solid

Results and discussion

Any other information on results incl. tables

Based on the release of bismuth in five artificial physiological test media, bismuth silicate is considered essentially insoluble in artificial interstitial fluid, sweat solution and PBS, and slightly soluble in gastric fluid (1.00 % bismuth released after 24 hours). Bismuth silicate is more soluble in artificial lysosomal fluid (51.71% of bismuth was released after 72 hours). 

The analytical results of the dissolution and bioaccessibility of test item bismuth silicate are summarized in the following Tables from 1a to 1e.

The % of dissolution was calculated considering an initial bismuth silicate load of 100 mg and a maximum possible bismuth release of 74769 µg/L (calculated from the test item composition).

TABLE 1a Bismuth Silicate:209Bi concentrations and % of dissolution in Artificial gastric fluid (pH 1.5)

 

Artificial gastric fluid

(pH 1.5)

209Bi

(µg/L)

Bismuth Silicate

(% of dissolution)

T0

(*)

Mean

n.d.

-

S.D.

-

RSD%

-

T2h

(**)

Mean

738

0.99

S.D.

29.42

RSD%

3.99

T8h

(**)

Mean

744

1.00

S.D.

22.71

RSD%

3.05

T24h

(**)

Mean

749

1.00

S.D.

20.71

RSD%

2.77

n.d.: lower than the Limit of Detection (L.O.D. = 0.50µg/L for Bi).

(*) This value is considered the contribution of the test medium.

(**) This value was calculated subtracting the relevant Control sample value, in order to consider the contribution of the test medium.

The between-vessel variation was less than 20 % in accordance with OECD Series No. 29(ENV/JM/MONO(2001)9).[SK1] 


TABLE 1b Bismuth Silicate:209Bi concentrations and % of dissolution in Phosphate buffered saline (PBS) (pH 7.2)

Phosphate buffered saline (PBS)

(pH 7.2)

209Bi

(µg/L)

Bismuth Silicate

(% of dissolution)

T0

(*)

Mean

n.d.

-

S.D.

-

RSD%

-

T2h

(**)

Mean

2.06

0.003

S.D.

0.09

RSD%

4.35

T24h

(**)

Mean

2.79

0.004

S.D.

0.05

RSD%

1.75

n.d.: lower than the Limit of Detection (L.O.D. = 0.50µg/L for Bi).

(*) This value is considered the contribution of the test medium.

(**) This value was calculated subtracting the relevant Control sample value, in order to consider the contribution of the test medium.

The between-vessel variation was less than 20 % in accordance with OECD Series No. 29 (ENV/JM/MONO(2001)9).

 

TABLE 1c Bismuth Silicate:209Bi concentrations and % of dissolution in Artificial lysosomal fluid (pH 4.5

Artificial lysosomal fluid

(pH 4.5)

209Bi

(µg/L)

Bismuth Silicate

(% of dissolution)

T0

(*)

Mean

n.d.

-

S.D.

-

RSD%

-

T2h(**)

Mean

7371

9.86

S.D.

608.67

RSD%

8.26

T24h

(**)

Mean

35606

47.62

S.D.

1230.32

RSD%

3.46

T72h

(**)

Mean

38663

51.71

S.D.

1450.85

RSD%

3.75

n.d.: lower than the Limit of Detection (L.O.D. = 0.50µg/L for Bi).

(*) This value is considered the contribution of the test medium.

(**) This value was calculated subtracting the relevant Control sample value, in order to consider the contribution of the test medium.

The between-vessel variation was less than 20 % in accordance with OECD Series No. 29 (ENV/JM/MONO(2001)9).

TABLE 1d Bismuth Silicate:209Bi concentrations and % of dissolution in Artificial sweat solution pH 6.5

Artificial sweat solution

(pH 6.5)

209Bi

(µg/L)

Bismuth Silicate

(% of dissolution)

T0

(*)

Mean

n.d.

-

S.D.

-

RSD%

-

T2h(**)

Mean

4.02

0.01

S.D.

0.30

RSD%

7.41

T24h

(**)

Mean

4.14

0.01

S.D.

0.38

RSD%

9.11

T72h

(**)

Mean

6.35

0.01

S.D.

0.30

RSD%

4.68

T168h

(**)

Mean

6.39

0.01

S.D.

0.16

RSD%

2.58

n.d.: lower than the Limit of Detection (L.O.D. = 0.50µg/L for Bi).

(*) This value is considered the contribution of the test medium.

(**) This value was calculated subtracting the relevant Control sample value, in order to consider the contribution of the test medium.

 The between-vessel variation was less than 20 % in accordance with OECD Series No. 29 (ENV/JM/MONO(2001)9).

TABLE 1e Bismuth Silicate:209Bi concentrations and % of dissolution in Artificial interstitial fluid (pH 7.4)

Artificial interstitial fluid

(pH 7.4)

209Bi

(µg/L)

Bismuth Silicate

(% of dissolution)

T0

(*)

Mean

n.d.

-

S.D.

-

RSD%

-

T2h(**)

Mean

n.d.

0.00

S.D.

-

RSD%

-

T24h

(**)

Mean

n.d.

0.00

S.D.

-

RSD%

-

T72h

(**)

Mean

n.d.

0.00

S.D.

-

RSD%

-

T168h

(**)

Mean

n.d.

0.00

S.D.

-

RSD%

-

n.d.: lower than the Limit of Detection (L.O.D. = 0.50µg/L for Bi).

(*) This value is considered the contribution of the test medium.

(**) This value was calculated subtracting the relevant Control sample value, in order to consider the contribution of the test medium.

The between-vessel variation was less than 20 % in accordance with OECD Series No. 29 (ENV/JM/MONO(2001)9).

Applicant's summary and conclusion

Conclusions:
Based on the release of bismuth in five artificial physiological test media, bismuth silicate is considered essentially insoluble in artificial interstitial fluid, sweat solution and PBS, and slightly soluble in gastric fluid (1.00 % bismuth released after 24 hours). Bismuth silicate is soluble in artificial lysosomal fluid (51.71% of bismuth was released after 72 hours). 
Executive summary:

The dissolution and bioaccessibility of test item bismuth silicate was conducted in five physiological media: phosphate-buffered saline (PBS) (pH 7.2), artificial interstitial fluid or Gamble’s solution (pH 7.4), artificial sweat solution (pH 6.5), artificial lysosomal fluid (pH 4.5) and artificial gastric fluid (pH 1.5)), selected  to simulate relevant human-chemical interactions. The dissolved amount of the test item was quantified by the mass concentration of bismuth using ICP-MS.

Based on the release of bismuth in five artificial physiological test media, bismuth silicate is considered essentially insoluble in artificial interstitial fluid, sweat solution and PBS. It is slightly soluble in gastric fluid and soluble in artificial lysosomal fluid. In gastric fluid 1.00 % bismuth was released after 24 hours and 51.71% of bismuth was released after incubation for 72 hours in lysosomal fluid. 

The study was conducted according to the standard methods and is GLP-compliant and therefore is considered reliable without restrictions.