Nanomaterials

A nanomaterial can be natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the nanoscale range 1 nm - 100 nm. Engineered nanomaterials (ENM) are materials between 1 nm and 100 nm manufactured to have specific properties or composition. Nanomaterial used at the university may include metal oxides such as zinc oxide and cerium oxide, gold, silver, Carbon Nano Tubes.

Nanomaterial exist in nature (for example milk contains nanoscale droplets of fat) but can also be manufactured or produced as a by-product. Overall there is consensus that nanomaterials cannot be considered either intrinsically safe or harmful. Generally, the types of hazards nanomaterials may present include:

• Physiological effects due to exposure through inhalation, ingestion, and/or skin penetration. Effects will depend on size, dose and reactivity of the material. Potential will depend on structure and form of the material.
• Explosion and fire. The potentially higher surface area and reactivity of nanomaterials within a dust cloud must be considered.  
• Adverse chemical reactions with incompatible material(s).
• Environmental contamination.

1.1.     Nanomaterial properties

Numerous types of nanomaterials are commercially available or able to be synthesised in the research environment. When identifying the hazard associated with a nanomaterial several attributes of the nanomaterial must be considered to help determine its toxicological affect:

• Particle size, shape, aspect ratio and degree of agglomeration: these aspects may determine if particulate nanomaterial(s) can become easily airborne/carried by air currents or how a nanomaterial may physically enter the body or form mixtures which can become explosive.
• Chemical properties, solubility, surface area and charge: such factors may provide an understanding on whether a nanomaterial may be toxic or react with other materials to result in inadvertent chemical reactions.

• Whether the material is classified as a carcinogen, mutagen, teratogen, reproductive toxicant or sensitizer. If the parent material is classified as such then it is possible the nanomaterial form may have the same toxic potential.
• Whether the nanomaterials are combustible: consider whether the handling processes can generate a risk from fires and explosions.
• Whether nanomaterials with highly reactive metal components are photo-reactive or have highly charged surfaces:

-         such nanomaterials when exposed to light, can release free radicals which could result in adverse physiological effects

-         charged nanomaterials may be problematic due to increased uptake by interaction with charged biological molecules

-         manufacturer guidance (such as the Safety Data Sheet) could advise further on this.

• Whether the nanomaterial is highly basic or acidic:

-         nanomaterials which have a highly acidic or basic pH may cause physiological problems at point of contact.

• Whether the nanomaterials are soluble:

-         nanomaterials which are soluble (especially in an aqua environment) can lead to adverse toxic effects to humans and the environment.

• Whether the nanomaterial is fibrous:

-         A nanofiber is a nanomaterial with two similar external dimensions in the nanoscale and the third dimension significantly larger. The aspect ratio is usually greater than 3:1. This is considered a High Aspect Ratio (fibrous) nanomaterial (HARN).

-         Some HARNs presents a risk of exposure through inhalation and may be retained in the pleural cavity of the lungs for long periods. Some Carbon nanotubes (CNT) are an example of HARN.

Given the limited hazard information available for nanomaterials it can be difficult to determine the toxicological effects. It may be necessary to refer to information already available for similar materials however it’s not always clear which properties can be assumed to apply to the nanomaterial. The greater the differences between the physical and chemical characteristics of your material and those of another material (even with the same chemical composition) the greater the uncertainty.

The Work Health and Safety Regulations 2017 (NSW) has specific requirements for workplace hazardous chemicals, this covers nanomaterials in the same way as other hazardous chemicals.

Prior to work with nanomaterials at UNSW, the hazards must be identified and appropriate control measures determined. The nature of the nanomaterial, the potential sources of exposure and the work processes must be detailed. Special attention should be given to the following work activities:

• Handling powder containing particulate nanomaterials
• Manufacturing particulate nanomaterials (especially those in the gas phase)
• Machining of materials containing nanomaterials (e.g. grinding, sawing)
• Spraying of liquids containing particulate nanomaterials
• Processing particulate nanomaterials in a liquid where a high energy output is involved
• Recycling and waste disposal of nanomaterials.

The risk management process should be documented using SafeSys or HS017 Risk Management Form. This guideline offers assistance in the types of control measures that may be implemented when working with nanomaterials. It is important to note that these controls are not exhaustive, and additional controls may be required based on industry best practice, manufacturer advice or advice obtained from other legitimate sources.

HS933a Nanomaterial Risk Control Banding can be used to assist in the determination of controls.  However, risk control banding makes assumptions and has limitations so should be used only to inform the assessment. Where there is uncertainty a precautionary approach should be taken to the risk management.

The manufacturer’s Safety Data Sheet (SDS) should first be consulted to identify what hazards may exist with the nanomaterial itself. The SDS will also cover hazards associated with any chemicals or stabilisers the nanomaterial may be part of or stored in. In some cases, a SDS may not be available (e.g. a nanomaterial has been fabricated on site or in another organisation such as another university for use here). In such cases, a methodical risk management approach should be taken to address known risks and reduce these to as low as reasonably practicable. This may be achieved by seeking guidance from a competent person(s), reviewing industry best practice or implementing controls such as those for other nanomaterials with similar properties, where the hazards and controls are known.

2.1.     Eliminate

In most cases, elimination may not be practicable. However, consideration should be given as to whether the use of nanomaterials can be eliminated from the proposed work.

2.2.     Substitute

Substitution of a known hazardous nanomaterial to one which is less hazardous, but is still suitable for the task, should be considered. Other substitution methods may include:

2.2.1.     Dry to wet: substitute dry powder with wet paste, slurries, solid state or even pelleted nanomaterials to minimise generation of uncontrolled particles. This may also include purchasing nanomaterials in liquid medium rather than as a dry powder.

2.2.2.     Machining: substitute high energy machining processes (e.g. electrical disc saw) for low energy machining (e.g. manual grinding or cutting), as this emits significantly lower levels of dust.

2.2.3.     Quantity: substitute the need for large quantities of nanomaterials to smaller amounts.

2.3.     Isolate

2.3.1.     Facility isolation: consider the use of a dedicated lab only for nanomaterial work. This may be a fully isolated area with remote control operations.

2.3.2.     Nanomaterial work zones: where an existing lab may be used for nanomaterial as well as other work, nanomaterial areas should be separated where possible. This may be achieved through physical barriers, curtains which seal, or similar. Physical barriers will also act to reduce the impact of an incident on other lab users.

2.3.3.     Local Isolation: isolate nanomaterial work using systems such as an enclosed glove box with HEPA filtration. This offers a high level of protection but may not be reasonably practicable, in which case partial enclosures can be used such as a fume cupboard.

2.4.     Engineering controls

2.4.1.     Extraction:

• The small size and low inertia of particulate nanomaterials means they can move in the air more like a gas than normal particles. Therefore, correctly designed and well maintained fume cupboards and Local Exhaust Ventilation (LEV) systems can offer good protection.
• Where reasonably practicable the exhaust air should be filtered through a High Efficiency Particulate Air (HEPA), preferably H14 (or ISO 45 H), to remove particulate nanomaterials before venting to outside the building.  This is particularly important when handling HARNs, such as carbon nanotubes or other fibrous/rod-like nanomaterials. Using double HEPA filtered cabinets increased the level of protection and allows a safer means of changing filters.
• Ducted fume hoods can be used. If handling HARNs then a HEPA filter is needed to prevent build-up of nanomaterial in ducting and dispersal into the environment. Vented air should never be recirculated unless it has passed through a HEPA filter.
• Ducted Biosafety Cabinets (BSC’s) can be used to handle particulate nanomaterials, they exhaust through a HEPA H14 (or ISO 45 H) filter. Class II BSCs are not suitable for handling HARNs and are only suitable for handling small (<1g) quantities because they re-circulate up to 70% of their air inside the cabinet.
• Ductless recirculating cabinets should not be used. If a ductless BSC is the only reasonably practicable option it must have HEPA filter and only be used for small quantities (<1g) and without any hazardous vapours or gases.
• Always check the manufacturer’s guidance or technical specifications.
• Cabinets/LEV must be installed in accordance with Australian Standards; operators carry out regular visual inspections; and be subject to regular thorough maintenance, including a filter integrity test, ideally every 6 months.

2.4.2.     Room air flow: a negative pressure work area may be required.

2.4.3.     Intrinsically safe equipment: use of intrinsically safe electrical equipment will prevent exposure of nanomaterial powder to ignition sources which can cause short circuit, sparks, fire or explosion.

2.4.4.     Capture systems: research grade sticky mats may be used to capture fallen nanomaterial, these would usually be located in higher risk areas such as:

• in glove boxes
• base of benches where work is being carried out
• under weigh balances
• lab entrance and exits (to collect any material from shoes)
• high use areas / thoroughfares.

2.4.5.     Containment vessels: handling of dry powdered nanomaterials should only be weighed inside a containment vessel (e.g. enclosed weigh balance, glove boxes).

2.4.6.     Wet cutting should be used wherever possible.

2.5.     Administrative

2.5.1.     Storage:

• Nanomaterials must be stored in accordance with their SDS.
• Store double contained, where practical.
• Powders should only be kept in sturdy sealed containers made from a compatible material to avoid inadvertent chemical reactions or accidental dispersion of materials if the container breaks.
• Nanomaterials must not be stored with incompatible chemicals (where known).
• Aliquoted nanomaterial substances / solutions which are used immediately need not be labelled (reference: UNSW HS429 Labelling of Hazardous Chemicals Guideline).

2.5.2.     Material handling:

• Keep the material wet or damp.
• Use instruments/tools to handle the nanomaterial to prevent contact.

2.5.3.     Avoid energetic processes that might generate airborne dusts.

2.5.4.     Work area and storage area should be away from ignition sources if there is a risk of a dust cloud.

2.5.5.     Use damp benchcote (absorbent paper) to capture any spills.

2.5.6.     Exposure time: minimise the number of people working with the nanomaterial and in the space. In addition, minimise the length of time working with the nanomaterial.

2.5.7.     Layout: carry out the work away from ignition sources, such as naked flames and non- intrinsically safe electrical equipment.

2.5.8.     Minimise sharps: sharps are objects that can break the skin and should be avoided, for example needles, blades, Pasteur pipettes etc. This will help to prevent accidental injection of nanomaterials into the body.

2.5.9.     Routine cleaning process: to prevent accumulation of nanomaterials on work area surfaces, a routine cleaning program should be implemented. Bench surfaces and other work areas should be routinely cleaned with wet disposable materials (e.g. damp paper towel) and discarded. Care should be taken not to raise dust. Where necessary use a HEPA filtered vacuum. Frequency of cleaning depends on activity, but it is advised that surfaces are cleaned each time work occurs.

2.5.10.  Training and supervision: workers should be trained on how to safely work with nanomaterials in accordance with the RMF/SWP, as well as any other training identified by the local area. The competency and supervision should be indicated in the RMF/SWP.

2.5.11.  Labelling and signage:

Under the globally harmonised system (GHS) for labelling, there is currently no specific pictogram for nanomaterials. If the nanomaterial is classified under the GHS then it must have the relevant GHS label. In addition, it may have a supplementary label to identify it as a nanomaterial. UNSW uses the label in image 1 to identify nanomaterial.

The UNSW Safety Hazards Poster placed on laboratory entrance doors should be used to advise of nanomaterial usage in the area. Labelling and signage should be used on all containers, vessels and pipework that contain nanomaterials. This is to alert people of the content of the container, vessel, or pipework and the need for caution. 

2.6.     Personal Protective Equipment (PPE)

Evidence on the ability of nanomaterials to penetrate the skin is still limited, and for this reason measures should be taken to prevent any skin contact. Light-coloured gloves, lab coats and work benches are recommended to facilitate observation of contamination by dark nanomaterials. The following offers some guidance on the types of PPE that may be used:

2.6.1.     Body protection: evidence suggests air-tight fabrics made of nonwoven textile may be more efficient than fabrics of woven cotton or polyester, at protecting against nanomaterials. If dust exposure could be significant, non-woven disposable lab coats or full body suits should be used that are made from a low dust-retention or low dust-release fabric such as polyethylene textiles (e.g. Tyvek/Tychem). If re-usable laboratory coats or overalls are used, provision should be made for their regular laundering and the prevention of secondary exposure. Where there has been a spill (i.e. “one-off” gross contamination), consideration should be given to the disposal of any such items as hazardous waste. When working with nanomaterial wear long trousers, with no cuffs.

2.6.2.     Hand protection: manufacturer guidance should be sought to determine the effectiveness of gloves for use with a given nanomaterial. Determination of the suitability of a glove for nanomaterial work should focus around glove thickness, pore size and resistance to other chemicals that may be associated with nanomaterial (dependent on solvent or dispersing agent). Nitrile or PVC gloves may offer better protection against dry powders and double gloving can also increase protection against exposure. If latex gloves are the safest choice, then only low protein, powder-free gloves should be used.

2.6.3.     Eye protection: close fitting safety glasses or goggles may be required depending on application (contact lenses may pose an increased risk and their use should be avoided).

2.6.4.     Respiratory protection: disposable P2 or P3 masks can be used as a secondary precautionary measure, not as a first line of defence. If there is an atmosphere containing airborne nanomaterials then a full-face P3 particulate respirator that protects the eyes and lungs is required. In this case a face fit test must be completed. Filters providing protection at the ultra-fine particle level should be considered for nanomaterial work (Refer to AS/NZS 1715 & 1716).

There are no legal workplace exposure limits or health monitoring requirements for nanomaterial in Australia. The physicochemical characteristics of nanomaterial present significant challenges in understanding the absorption, distribution, metabolism, and excretion. Monitoring is limited due to lack of instrumentation sensitive to nanomaterials and the presence of natural background level of nanomaterials in the air (including from urban pollution). Safe Work Australia have made some suggested workplace exposure limits for single-walled and multi-walled carbon nanotubes (0.001mg/m³ time weighted average) and titanium dioxide (0.3mg/m³).  The preferred option at UNSW is to prevent potential exposure with rigorous control measures rather than a monitoring regime.

As a precautionary measure UNSW advises the completion of a HS933b Nanomaterial Work Record for all persons working with nanomaterials with unknown toxicological properties. This record is to be kept for 40 years in their Personnel File.

4.1.     Spills

The management of spills will vary in accordance with the type of material spilt. In the event of a spill, a systematic approach needs to be taken that includes recommendations listed under the manufacturer’s SDS or any other relevant guidance. General controls for spill management should consider the following:

• Dry material should not be brushed or swept; instead damp wet methods should be used.
• Compressed air must not be used for cleaning.
• HEPA filter respirator(s) must be used for large spills (where considerable dust and airborne particles are released in much of the room).
• Standard vacuum cleaners are not to be used for cleaning. If a vacuum cleaner is required, it must be HEPA-filtered and dedicated only for nanomaterial material work. It should be designed to minimise risk of ignition of a combustible nanomaterial. The filter needs to be regularly changed under controlled conditions as this will contain particulate nanomaterial dust. The vacuum itself will also need to be treated as hazardous waste at the end of its life.
• Use mops with disposable heads.
• Use light-coloured wet-wipes.
• Use mist/fog generating equipment.

Nanomaterial waste is to be treated like chemical waste and discarded in accordance with the parent material waste category in UNSW HS321 Laboratory Hazardous Waste Disposal Guideline.

This Guideline supports the University’s compliance with the following legislation:

Work Health and Safety Act 2011 (NSW)

Work Health and Safety Regulations 2017 (NSW), (Regulations 328 – 391)

HS933a Nanomaterial Risk Control Banding

HS933b Nanomaterial Work Record

• Working Safely with Nanomaterials in Research & Development, The UK NanoSafety Group (UKNSG), May 2016
• Safety Hazards of Engineering Nanomaterials Information Sheet, Safe Work Australia, May 2013.
• Safe Handling and Use of Carbon Nanotubes, Safe Work Australia, March 2012.
• Engineering Nanomaterials: An Update on the Toxicology and Work Health Hazards, Safe Work Australia, January 2015.
• Emissions of Nanomaterials During Machining Processes Information Sheet, Safe Work Australia, May 2013
• Nanotechnologies – Occupational risk management applied to engineered nanomaterials – Principles and approaches, ISO/TS 12901-1:2012
• Nanotechnologies – Occupational risk management applied to engineered nanomaterials – Use of the control banding approach, ISO/TS 12901-2:2014
• An evaluation of MSDS and Labels associated with the use of Engineering Nanomaterials, Safe Work Australia, June 2010.
• The use of Nanomaterials in UK Universities: an overview of occupational health and safety, Health and Safety Executive, January 2013.
• Using nanomaterials at work, HSG272 Health and Safety Executive, March 2013
• ISO 29463 High Efficiency filters and filter media for removing particles in air, 2017. (Procedures and classification schemes prescribed in ISO 29463 is valid for filters used for nanomterials.)
• http://www.safenano.org
• https://www.nanosafetycluster.eu/