Silicic acid, calcium salt

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Basic data given, meets generally accepted scientific standards, acceptable for assessment

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1966

Report date:

1966

Reference 2

Reference Type:

publication

Title:

No information

Author:

Langendorf H, Lang K

Year:

1967

Bibliographic source:

Zeitschrift fuer Ernaehrungswissenschaft, 8, 27-32

Materials and methods

Objective of study:

excretion

Principles of method if other than guideline:

Study in volunteers: Oral ingestion of an SAS amount in a drink, determination of Si in urine prior and after to administration.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Silicon dioxide

EC Number:

231-545-4

EC Name:

Silicon dioxide

Cas Number:

7631-86-9

Molecular formula:

O2Si

IUPAC Name:

dioxosilane

Details on test material:

Aerosil, CAS-Name: Silica, amorphous, fumed, cryst.-free; CAS-No. 112945-52-5

FK 700, Silica, amorphous, precipitated, crystalline-free, CAS No. 112926-00-8

Radiolabelling:

no

Test animals

Species:

human

Sex:

male/female

Administration / exposure

Route of administration:

other: oral in juice

Vehicle:

other: apple juice, 0.5% suspension

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Mixing appropriate amounts with (Type of food): 2.5 g of test substance in 0.5 L (apple juice)

VEHICLE
- Concentration in vehicle: 0.5 %
- Amount of vehicle (if gavage): 0.5 L


HOMOGENEITY:
Suspension

Duration and frequency of treatment / exposure:

1x/day, given in two portions (see below)

Doses / concentrations

Remarks:

Doses / Concentrations:
Males: 2x 1250 mg (morning and midday) Females: 2x 1250 mg (morning and midday)

No. of animals per sex per dose / concentration:

Males: 10; Females: 2 (age 22 - 28 years)
(for each test article: 5 m+ 1 f )

Control animals:

other: untreated control = each volunteer before silica intake

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine
- Time and frequency of sampling: for 3 days pre-application and for 4 days post-application, total daily urine

- Method type(s) for identification: SiO2 determination according to Baumann (after alkaline hydrolysis with molybdate)
- Limits of detection and quantification: no data

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:

no data

Details on distribution in tissues:

no data

Details on excretion:

see below "Remarks on results.."

Toxicokinetic parameters

Toxicokinetic parameters 1

Test no.:

#1

Toxicokinetic parameters:

other: Aerosil - urinary excretion: <0.5 % of the dose applied within 4 days p.a.

Toxicokinetic parameters 2

Test no.:

#2

Toxicokinetic parameters:

other: FK 700 - urinary excretion: <0.5 % of the dose applied within 4 days p.a.

Metabolite characterisation studies

Details on metabolites:

not applicable

Any other information on results incl. tables

Daily urinary excretion of SiO₂ in volunteers before and after ingestion of synthetic amorphous silica 

Aerosil (pyrogene)
Test person	1	2	3	10	11	12
Sum SiO2 day 1 – 3 [mg/d] (control)	34.5	86.9	62.8	40.4	25.3	36.2
Sum SiO2 day 4 – 7 [mg/d] (test phase)	32.3	64.5	61.3	60.8	44.5	52.9

FK 700 (precipitated)
Test person	4	5	6	7	8	9
Sum SiO2 day 1 – 3 [mg/d] (control)	42.4	36.8	71.4	16.1	39.9	27.4
Sum SiO2 day 4 – 7 [mg/d] (test phase)	52.2	57.0	81.4	20.4	58.3	21.8

During the four days post-treatment, significant changes of the renal SiO2 excretion were not seen.

Daily SiO2 increments in urine after ingestion ranged between individually 7 and 23 mg, but were barely distiguishable

from the baseline level.

Aerosil:
The individual baseline values of the pretest phase were very variable and individually different, mean excretion rates ranging from 

25 to 87 mg/d. In the post-treatment phase, individual mean excretion rates ranged from 32 to 61 mg/d. 

FK 700: 
The individual baseline values of the pretest phase were very variable and individually different, mean excretion rates ranging 

from 16 to 71  mg/d. 

In the post-treatment phase, individual mean excretion rates ranged from 20 to 81 mg/d. 
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Overall, increases in excretion of SiO2 after oral ingestion were not unequivocally detectable. 

The small apparent increases on the average of less than 0.5 % of the total dose were in marked contrast to the high dose of 2500 mg SiO2 applied.  

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