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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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Diss Factsheets

Classification & Labelling & PBT assessment

PBT assessment

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Administrative data

PBT assessment: overall result

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Name:
zinc oxide standard
Type of composition:
boundary composition of the substance
State / form:
solid: particulate/powder
Reference substance:
zinc oxide standard
Name:
zinc oxide lower grade
Type of composition:
boundary composition of the substance
State / form:
solid: particulate/powder
>= 95 - < 99.7 % (w/w)
Reference substance:
zinc oxide lower grade
Reference substance:
zinc oxide lower grade
This impurity is considered relevant for the classification and labelling of the substance
Name:
Zinc oxide nano - hydrophobic surface treatment
Type of composition:
boundary composition of the substance
State / form:
solid: nanoform
Reference substance:
Zinc oxide nano - hydrophobic surface treatment
Type of information reported:
set of nanoforms
Name of set of nanoforms:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano - hydrophobic surface treatment
Shape category:
spheroidal
Shape:
spherical
Pure shape:
yes
Shape category:
spheroidal
Percentile:
D10
Range:
>= 5.8 - <= 34.2 nm
Percentile:
D50
Range:
>= 12.9 - <= 70.8 nm
Percentile:
D90
Range:
>= 27 - <= 117.4 nm
Additional information:
All materials in this group are identified as nanomaterials by the REACH definition, and are all in the spheroidal category.
Fraction of constituent particles in the size range 1-100 nm:
>= 90 - <= 100 %
Structure:
crystalline
Name:
wurtzite
Pure structure:
yes
Crystal system:
hexagonal
Description:
The zinc oxide nanos in this group have a hexagonal crystal system and a P6(3)mc (nr = 186) space group.
Range of specific surface area:
>= 10 - <= 51 m²/g
Surface treatment applied:
yes
Does the set contain both treated and non-surface treated nanoforms?:
no
Surface treatment name:
Silanes
Order:
#1
Surface treatment agent:
Zinc oxide nano - hydrophobic surface treatment
External layer:
hydrophobic
Description:
DESCRIPTION
All of the nanos have a hydrophobic coating, to include: triethoxycaprylylsilane, dimethicone, dimethoxydiphenylsilanetriethoxycaprylylsilane polymer or triethoxyoctylsilane.

DESCRIBE THE PROCESS BEHIND THE SURFACE FUNCTIONALISATION / TREATMENT:
- Main features of the surface treatment/functionalisation process: ZnO-nano is produced by pyrometallurgical (or high temperature) processes:
• Solid zinc bearing material is fed continuously into a plasma furnace at very high temperature
• Zinc is vaporized in the furnace, and is oxidised in the gasphase forming nano-ZnO
• After cooling, the nano-ZnO is caught in a closed chamber, from where it is transferred to specialized packaging units.
From the entrance of the zinc bearing material (e.g.: zinc metal, Zn powder, ZnO powder…) into the system until the collection (in specialized installation) of the nano-powder at the end of the manufacturing line, the process is entirely enclosed.
ZnO-nano can also be produced by wet chemical process
A hydrophobic coating is then applied to facilitate the integration/mixing of the substance in the final application.
Percentage of coverage of particle surface, %:
>= 20 - <= 100
Name:
Zinc oxide nano with and without hydrophilic surface treatment
Type of composition:
boundary composition of the substance
State / form:
solid: nanoform
Reference substance:
Zinc oxide nano with and without hydrophilic surface treatment
Type of information reported:
set of nanoforms
Name of set of nanoforms:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Reason / purpose:
justification for reporting set of similar nanoforms
Related information:
Zinc oxide nano with and without hydrophilic surface treatment
Shape category:
spheroidal
Shape:
spherical
Pure shape:
yes
Shape category:
spheroidal
Percentile:
D10
Range:
>= 4.7 - <= 38 nm
Percentile:
D50
Range:
>= 8.9 - <= 96.6 nm
Percentile:
D90
Range:
>= 16.1 - <= 175.7 nm
Additional information:
All materials in this group are identified as nanomaterials by the REACH definition, and are all in the spheroidal category.
Fraction of constituent particles in the size range 1-100 nm:
>= 90 - <= 100 %
Structure:
crystalline
Name:
wurtzite
Pure structure:
yes
Crystal system:
hexagonal
Description:
The zinc oxide nanos in this group have a hexagonal crystal system and a P6(3)mc (nr = 186) space group.
Range of specific surface area:
>= 10 - <= 100 m²/g
Surface treatment applied:
yes
Does the set contain both treated and non-surface treated nanoforms?:
yes
Surface treatment name:
hydrophilic coating
Order:
#1
Surface treatment agent:
Zinc oxide nano with and without hydrophilic surface treatment
External layer:
hydrophilic
Description:
Only three of the nanos have a hydrophilic coating. The hydrophilic coatings which were used were hydrated silica for one of the nanos and aminosilanes for two of the nanos.
The rest of the nanos in this group are uncoated and do not have any additional surface treatment.

DESCRIBE THE PROCESS BEHIND THE SURFACE FUNCTIONALISATION / TREATMENT:

- Main features of the surface treatment/functionalisation process: ZnO-nano is produced by pyrometallurgical (or high temperature) processes:
• Solid zinc bearing material is fed continuously into a plasma furnace at very high temperature
• Zinc is vaporized in the furnace, and is oxidised in the gasphase forming nano-ZnO
• After cooling, the nano-ZnO is caught in a closed chamber, from where it is transferred to specialized packaging units.
From the entrance of the zinc bearing material (e.g.: zinc metal, Zn powder, ZnO powder…) into the system until the collection (in specialized installation) of the nano-powder at the end of the manufacturing line, the process is entirely enclosed.
ZnO-nano can also be produced by wet chemical process

For the nanos with a surface treatment, a hydrophilic coating is then applied to facilitate the integration/mixing of the substance in the final application.
Percentage of coverage of particle surface, %:
>= 20 - < 100
PBT status:
PBT assessment does not apply
Justification:

According to regulation (EC) 1907/2006 (REACH) a PBT and vPvB assessment shall usually be conducted as foreseen in Article 14 (3) (d) in conjunction with Annex I Section 4 and according to the criteria laid down in Annex XIII. However, according to Annex XIII a PBT and vPvB assessment shall not be conducted for inorganic substances. ZnO is an inorganic substance, thus a PBT and vPvB assessment is not required.

Still, the points below are raised:

Zinc is a natural, essential element, which is needed for the optimal growth and development of all living organisms, including man. All living organisms have homeostasis mechanisms that actively regulate zinc uptake and absorption/excretion from the body; due to this regulation, zinc and zinc compounds do not bioaccumulate or biomagnify.

Zinc is an element, and as such the criterion “persistence” is not relevant for the metal and its inorganic compounds in a way as it is applied to organic substances. The removal of inorganic substances from the water column has been discussed as a surrogate for persistence. In section 4.6 (of the CSR), the rapid removal of zinc from the water column is documented. So, zinc does not meet this criterion, neither.

Considering the above, zinc and zinc compounds (including nano forms) are not PBT or vPvB.