Nanomaterials

Groso et al.: Management of nanomaterials safety in research environment. Particle and Fibre Toxicology 2010 7:40.

Definition of nanomaterials

In October 2011, the European Commission adopted the following definition of a ‘Nanomaterial’:

A 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 size range 1 nm – 100 nm. By derogation from the above, fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm should be considered as nanomaterials.

 

Here we take into consideration only engineered nanomaterials (ENMs), nanolayers with one dimension of less than 1nm, and multiwall carbon nanotubes.

Occupational health and safety concerns

Exposure to ENMs may occur via inhalation, dermal contact and ingestion. The most critical route of exposure is via inhalation.

Initial experimental studies with ENMs in cell cultures and laboratory animals have shown that the biological response to certain ENMs can be greater compared to larger particles with the same chemical composition (for the same mass dose).

In addition to the particle number and surface area, other particle characteristics may influence the biological response to ENM. These include solubility, shape, charge and surface chemistry, catalytic properties, adsorbed pollutants (and other intentional and unintentional surface changes), as well as the degree of agglomeration.

Work with Nanomaterials

Precautionary approach in controlling exposure

Without complete scientific evidence, the potential threat of newly developed materials on human health and environment is assumed to be such that precautionary measures should be taken until the material is known to be harmless.

In order to minimize potential exposure to engineered nanomaterials (ENMs), a combination of strategic, technical, organizational and personal protective measures is implemented.

The 4 main strategic measures are:

  1. Replace highly toxic raw materials/products with less toxic ones.
  2. Change the physical form of the product or material: use dispersions, pastes, granules or composites instead of powders or aerosols.
  3. Replace dry processes with wet processes.
  4. Enclose the process (restrict human contact)

 

Internal EPFL directive on work with ENMs

Once strategic measures are applied to the extent possible, technical, organizational and personal protection measures have to be applied as well to ensure you work with ENMs in the safest way. These measures are specified in the internal EPFL directive that regulates the safety aspects of the activities with ENMs.

If you are concerned by ENM production or use: you have to classify your laboratory into one of the three Nano hazard levels (1, 2 or 3) according to the internal directive.

If the obtained classification is Nano 1: the laboratory must follow the safety measures given in Appendix 5 and 6 of the directive.

If the obtained classification is Nano 2 or Nano 3: the laboratory responsible has to contact us (preferably by email).

The SCC will analyze the activities in detail, evaluate the possibility of reducing the Nano class and/or of regrouping the activities. As a result of this more detailed analysis, a definitive Nano class of the laboratory is defined and corresponding measures have to be followed.

Enclosure strategies

Under the assumption that even hazardous substances pose no risk when confined, the best option when working with engineered nanomaterials is to confine the entire process, if feasible. Examples of such confined systems are glove boxes or sealed chambers.

Health check registration

A preventive medical examination (with a five year interval) is mandatory for all those who:

  • Work in areas classified Nano 2 and Nano 3;
  • Have an annual duration of exposure of more than 30 days or 200 hours.

If you satisfy these two criteria, please send us an email, specifying the type and class of nanomaterial and the duration of exposure.

Exposure standards for nanomaterials

Workplace exposure standards refer to the airborne concentrations of a particular chemical or substance present in the workers’ breathing zone that should not cause adverse health effects or undue discomfort to nearly all workers.

Exposure standards for ENMs have not yet been established in Switzerland or internationally. The only exceptions are:

  • nanoparticles of TiO2 with an indicative exposure limit of 0.3 mg/m3 (alveolar fraction)
  • carbon nanotubes and nanofibers (with length more than 5 μm, diameter less than 3 μm and ratio of length over diameter more than 3:1) whose limit is set to 0.01 fibre/ml.