Silicon dioxide

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CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name

Silicon dioxide

Synonyms

Silica, Quartz, Silicic oxide, Silicon(IV) oxide, Crystalline silica, silica gel precipitated, crystalline-free*

IUPAC name

Silicon dioxide

CAS No

7631-86-9, 112926-00-8*

REACH registration number

 

EC No

231-545-4

Molecular formula

O2Si

Substance group/chemical family

mono-constituent substance/inorganic
 

Appearance

Physical state

Odour

Form

Colour

 

powder

odourless

crystalline and non-crystalline

white

USES AND HANDLING ISSUES

Relevant identified uses

It is used as filler in rubber products, paints, animal feeds, pedticides, insulation materials, and cosmetics. Silica nanoparticle applications include lukema cell biomarkers, cancer therapy, drug delivery, mechanical polishing, and additives to drugs, cosmetics, printing inks, varnishes, and food. Polycrystalline silicon and silicon dioxide materials are etched in semiconductor manufacturing. [3]

Handling considerations

Use safety glasses, lab coat, dust respirator, gloves.

PHYSICO-CHEMICAL PROPERTIES

Molecular weight

60,08 g/mol

Bulk density/Specific gravity

0,03-1 g/cm3 (20 °C) [5] /2,2 [8]

pH

3,5-9 (25 °C and 40-50 g/l) [5]

EC

 

Melting point

1713 °C [5]

Boiling point

2950 °C

Flash point

 

Flammability

 

Vapour density

 

Vapour pressure

13,3 hPa (1732 °C) [7]

Solubility in water

15-439,52 mg/l (20-37 °C, pH=5,5-7,4) [5]

Solubility in organic solvents

 

Hydrolysis

 

Ionicity in water

ion exchange processes possible [7]

Surface tension

 

Dispersion properties

 

Specific surface (BET)

 50 to 400 m2/g (Synthetic amorphous silica, pyrogenic) [5]

Stability and reactivity

Chemical stability

high stability [6]

Reactivity hazards

 

Corrosivity

 

Polimerization

 

Incompatibility with various substances

 

Special remarks on reactivity

 

Physical, chemical and biological coefficients

Koc

 21.73 (The log of the adsorption coefficient (KOC) of Silica was estimated to be log KOC = 1.3370 which is equal to a KOC value of 21.73 using the KOCWIN v2.00 QSAR method) [5]

Kow(log Pow)

0.53 (25 °C, pH: 7) (QSAR method) [5]

pKa

 

Henry-constant

 9.652E-012 atm-m3/mole (9.780E-007 Pa-m3/mole)(at 25 °C) (QSAR method) [5]

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

 

General terrestrial fate

 

General aquatic fate

 

General atmospheric fate

 

General persistence and degradability

 

Abiotic degradation and metabolites

 

Biodegradation and metabolites

not applicable [6]

Bioconcentration

not bioaccumulating due to inherent substance properties [7]

Volatilization

 

Photolysis

stable

Hydrolysis

stable The level of maximum solubility: 2.7 mmol SiO2/litre, constant in a broad range of pH (1.1 < pH < 8.9). The surface of silica may be covered by a partial hydrolysed gel layer when in contact with water. [5]

Soil adsorption and mobility

The log of the adsorption coefficient (KOC) of Silica was estimated to be log KOC = 1.3370 which is equal to a KOC value of 21.73 using the KOCWIN v2.00 QSAR method.

ENVIRONMENTAL CONCENTRATIONS

Measured data

 

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem          

Acute toxicity (LC50, EC50)                                               

Aquatic invertebrates

 

 

 

 

Aquatic algae and cyanobacteria

 

 

Sediment toxicity

Terrestrial systems

LC50 (4 days) 2.594 g/L [5]

LC50 (48 h) 512.078 mg/L [5]

EL50 (24 h) 1 g/L [5]

EL0 (24 h) 1 g/L [5]

 

EC50 (4 days) 217.576 mg/L [5]

EL50 (72 h) 10 g/L [5]

 

LC50 (14 days) 148.41 mg/kg sediment dw [5]

Chronic toxicity (NOEC, LOEC)

 

Aquatic invertebrates

 

Aquatic algae and cyanobacteria

 

Terrestrial systems

NOEC (30 days) 34.223 - 346.737 mg/L  [5]

 

NOEC (30 days) 42.11 mg/L [5]

NOELR (72 h) 10 g/L [5]

HUMAN HEALTH EFFECTS and PROTECTION

Routes of human exposures

oral, dermal, inhalation

General effects

Silicosis (i.e., nodular pulmonary fibrosis) caused by the inhalation and deposition of respirable crystalline silica particles [4]

Pulmonary tuberculosis and other infections [4]

Lung cancer[4]
Autoimmune-related disease[4]
Renal disease[4]

Chronic obstructive pulmonary disease[4]

Endocrine disruption

 

Mutagenicity

male rat alveolar cells, in vivo, inhalation, 3 mg/m3 aerosol (crystalline silica) 6hr/day, 5day/week for 13 week, positive [1

Carcinogenicity

male, female rat – inhalation: 0; 50 mg/m3 6 hr/day, 5 day/week for up to 24 month (study duration 24month),

lung: carcinoma or aenoma

female rat – inhalation: 0; 1 mg/m3 6hr/day, 5day/week 24 month (study duration: 25,5 month), lung: tumor

female rat – intratracheal: 3 mg of 0,09-0,2 μm particles given as 10 instillations before week 26, study duration 112 week or no treatment

lung: Bronchiolo-alveolar adenoma (22/7 experimental animals vs 0/46 control animals), low incidence of begign tumors [1]

Reprotoxicity


 

Teratogenicity

 

Skin, eye and respiratory irritations

 

Metabolism:

absorption, distribution & excretion

It is not irritating to skin and eyes.  [6]

 

SAS forms [CAS No 7631-86-9] are rapidly eliminated from the lung tissue during and after prolonged inhalation exposure of experimental animals with no disproportionate disposition occurring in the mediastinal lymph nodes, whereas crystalline forms exhibit a marked tendency to accumulate and persist in the lung and lymph nodes. Intestinal absorption of SAS appears to be insignificant in animals and humans. There is evidence of ready renal elimination of bioavailable fractions. [6]

Exposure limits

NIOSH REL: TWA 6 mg/m3 [8]

IDHL: 3000 mg/m3 [8]

OSHA PEL: TWA 20 mppcf (80 mg/m3/ %SiO2)

Drinking water MAC

 

Other information

fibrogenic [3]

Animal toxicity data

Acute toxicity (LD50)

oral: LD50 5 000 mg/kg bw (rat) [5]

inhalation: LC50 (4 h) 140 - 58 800 mg/m³ air (rat) [5]

dermal: LD50 2 000 - 5 000 mg/kg bw (rabbit) [5]

Chronic toxicity (NOEL, LOEL)

oral: NOAEL (rat): 2 500 mg/kg bw/day [5]

NOEL (rat): 4 000 - 8 980 mg/kg bw/day [5]

inhalation: NOAEC (rat): 1.3 - 10 mg/m³ air [5]

NOEC (rat): 1.3 mg/m³ air [5]

LOAEC (rat): 5.9 mg/m³ air [5]

ENVIRONMENTAL STANDARDS AND REGULATIONS

EINECS regulation

 

OSHA regulations etc.

 

OTHER INFORMATION, SPECIAL REMARKS

 CREATED, LAST UPDATE

Created:

Last update:

10th April, 2018

29th May, 2018

REFERENCES

[1] TOXNET – Toxicology Data Network.

https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/f?./temp/~7yHgsY:4

[2] TOXNET – Toxicology Data Network.

https://chem.nlm.nih.gov/chemidplus/rn/7631-86-9

[3] Haz-Map.

https://hazmap.nlm.nih.gov/category-details?table=copytblagents&id=620

[4] Chemical Safety Information from Intergovernmental Organizations.

http://www.inchem.org/documents/cicads/cicads/cicad24.htm

[5] European Chemicals Agency (ECHA).

https://echa.europa.eu/brief-profile/-/briefprofile/100.028.678

https://echa.europa.eu/hu/registration-dossier/-/registered-dossier/15556

[6] OECD Existing Chemicals Database. https://hpvchemicals.oecd.org/UI/handler.axd?id=49b7307e-56d7-44d5-a15c-4e6d1ed25359

[7] OECD Existing Chemicals Database.

https://hpvchemicals.oecd.org/UI/handler.axd?id=81d3694a-a582-4fa8-a8f2-f771459b67ed

[8] OSHA – Occupal Safety and Health Administration, Occupational Chemical Database.

https://www.osha.gov/chemicaldata/chemResult.html?recNo=613