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Posted: August 5, 2010
New Safe Work Australia report investigates feasibility of exposure standards for nanomaterials
(Nanowerk News) The focus of the new report "Engineered Nanomaterials: Feasibility of establishing exposure standards and using control banding in Australia" is to investigate the feasibility of:
– establishing group-based Australian National Exposure Standards for engineered
– using control banding for engineered nanomaterials in Australia.
In December 2007, the British Standards Institution (BSI) published: "Nanotechnologies –
Part 2: Guide to safe handling and disposal of manufactured nanomaterials" (the BSI Guide).
The BSI Guide defines four hazard type groups for engineered nanomaterials, includes
information on benchmark exposure levels (BELs) which are guidance on control levels for
nanomaterials in those groups, and provides control guidance for those groups based on
control banding. Investigating the feasibility of establishing group-based Australian National
Exposure Standards and using control banding for engineered nanomaterials involved a
detailed assessment of the groups, the BELs and the guidance based on control banding.
While there are some issues associated with the hazard type groups suggested in the BSI
Guide, they appear to be practical groupings of nanomaterials. In relation to each of the
BELs proposed in the BSI Guide for each of the hazard type groups, this report finds:
– The BEL for insoluble fibrous nanomaterials should be modified to 0.1 fibre/ml,
rather than the 0.01 fibre/ml recommended in the BSI Guide, as there is no
evidence that these nanomaterials are more toxic on a fibre-by-fibre basis than
asbestos, and also, a higher number of fibres will be counted by electron
microscopy which is needed to resolve fine fibres, e.g. carbon nanotubes. This
BEL may also be applied to poorly soluble fibrous nanomaterials.
– There is currently limited scientific evidence to support a quantitative BEL for
nanomaterials which are already classified in their larger form as carcinogenic, a
reproductive toxin, asthmagenic or mutagenic (CMAR) of 0.1xWEL, as proposed
in the BSI Guide. This was a recommendation based on prudence and a rule of
thumb, and should be supported by following a precautionary approach until
knowledge is enhanced.
– In regard to insoluble nanomaterials, there is toxicological evidence to support the
BSI Guide recommendation of a quantitative BEL of 0.066xWEL for
nanomaterials similar to TiO2, but there is a lack of quantitative evidence for most
insoluble nanomaterials. Combining the use of mass-based BELs and the particle
number concentration BEL of 20 000 particles/ml may be the optimum approach.
The particle size range over which a particle number concentration BEL should
be measured needs to be defined.
– Although there is currently insufficient evidence to support the BSI
recommendation of a quantitative BEL of 0.5xWEL for soluble nanomaterials, this
may be prudent due to the possibility that the size, shape and surface chemistry
of soluble nanoparticles may lead to increased dose rates, or doses to parts of
the body not usually exposed to such materials. However, a number of soluble
nanomaterials do not have bulk forms for which exposure limits are set.
If quantitative exposure limits or benchmark exposure levels are adopted, then one approach
is to adopt them as BELs (guidance) initially, and convert to National Exposure Standards as
further hazard, risk and measurement data become available.
There are a number of initiatives internationally to consider the control banding methodology
as a means to effectively control nanomaterials in the workplace. Two control banding
approaches examined in this report look promising:
– the Control Banding Nanotool, which has been specifically designed for control of
– use of the control banding guidance in the BSI Guide should enable organisations
to reduce exposures below the BELs. Exposures below the BELs should be
achievable using conventional engineering controls.
Control banding for the nanomaterial industry is likely to be a suitable risk control approach
for managing nanoparticle exposure in many situations. Control banding is particularly
favourable to the control of chemical hazards where there is limited toxicological information
and workplace exposure limits are absent as is currently the case with engineered
However, in general, Australian workplaces do not have wide experience of using the control
banding approach for other hazards and this situation is likely to remain so until there is
impetus nationally to accept the control banding approach in support of State, Territory and
Commonwealth regulations. Therefore, if control banding is to be used, it should be used in
combination with the conventional approach towards the assessment and control undertaken
in the current jurisdictional regulations, including those existing for human carcinogens.
The use of both benchmark exposure levels and control banding, as proposed in the BSI
Guide, are consistent with a precautionary approach to handling nanomaterials, as
recommended by Safe Work Australia where limited information about hazards and risks is
There is a need to develop further capability of measuring nanomaterial exposures, which
will also enable assessment of control against Benchmark Exposure Levels. The OECD
Working Party for Manufactured Nanomaterials (WPMN) guidance for emissions
measurement of nanomaterials appears to be a practical way to measure nanomaterial
exposures in workplace settings. This is currently being validated by Queensland University
of Technology and Workplace Health and Safety Queensland in a project commissioned by
Safe Work Australia. Following completion of the validation, focus should be placed on
dissemination of the methodology to occupational hygienists in Australia. The methodology
can be used to assess performance against BELs.
Recent literature reviews and industry surveys (overseas) suggest that there is a need for
guidance on the safe handling, control and disposal of nanomaterials in the industry.
Currently, there are no Australian guides for safe handling and control of specific engineered
nanoparticles that can be incorporated into the current legislation framework used within
Australia. CSIRO is currently developing guidance for safe handling and disposal of carbon
nanotubes for Safe Work Australia.