Effective December 31, 2007, BSI British Standards issued "Public Document" PD 6694-2:2007, "Nanotechnologies — Part 2: Guide to safe handling and disposal of manufactured nanomaterials." A short summary of this important standardization document follows.
BSI drafted this safe-handling document to provide "guidance on assessing risks and recognizing uncertainties in the development, manufacture and use of nanomaterials and on developing and implementing an effective strategy to address and control the risks." As with BSI’s other recent nano-related documents, it is inapplicable to natural and incidental nanoparticles.
Inhalation Risks: The document analyzes 30 major reviews and position papers on the possible health risks of exposure to certain nanomaterials. The core EHS issue for BSI is whether, "due to their small size, nanoparticles can reach parts of biological systems which are not normally accessible by larger particles." BSI also notes possible translocation risks and poses that if surface area is a driver of toxicity, then increased toxic effects should be expected from nanoparticles. Additionally, BSI notes that a reduction in particle size sometimes causes increased particle solubility, which might in turn lead to increased bioavailability.
Dermal Exposure or Ingestion Risks: BSI notes that there are very few studies on dermal exposure nanoparticles "and these have not demonstrated skin penetration by nanoparticles to any extent." However, BSI notes that future studies should consider the effect of nanoparticle exposure on damaged skin, and "until consensus emerges, a prudent approach would be to limit exposure to the skin." Regarding ingestion exposure routes, BSI postulates that there may be nanoparticle transfer across gastro-intestinal walls in certain circumstances. However, BSI clearly explains that there is "[p]resently no direct evidence that any occupational ill health is caused by this effect, but it would be prudent to minimize exposure by this route."
Nanoparticle as Hazardous Materials: BSI notes that "given lack of current knowledge about the toxicity of nanomaterials and the concern that current MSDs do not adequately reflect the hazardous nature of nanomaterials, it is recommended that all nanomaterials are considered potentially hazardous unless sufficient information to the contrary is obtained." This conclusion should resonate with many advocates’ reliance on the precautionary principle.
Risk management approaches: BSI borrows heavily from general EC principles set forth in Control of Substances Hazardous to Health (COSHH) m 2002. That document identifies six basic risk management steps: (1) Identify the hazards and assess the risks; (2) Decide what precautions are needed; (3) Prevent or adequately control exposure; (4) Carry out appropriate health surveillance; (5) Prepare accident/emergency plans; and (6) Inform, train and supervise employees.
Information collection: Regarding information collection for nanomaterials, BSI suggests collecting: the commercial and technical names of material; the material’s MSDS; chemical composition information; and nanomaterial presence and proportion data. BSI also encourages companies to consider the following questions: are the particles long and thin?; how dusty is material?; does the material contain dust suppressants?; are the nanoparticles bound into another material?; is the substance water soluble?; and finally, "how hazardous or toxic is the material?"
Risk Evaluation: Regarding risk evaluation, BSI believes the first consideration should be inhalation risks followed by dermal exposure and ingestion. BSI breaks down nanoparticles into four groups for categorization of nanomaterials for risk evaluation purposes: (1) fibrous; (2) CMAR (carcinogenic, mutagenic, asthmagenic, reproductive toxin in bulk form); (3) insoluble; and (4) soluble. (See below).
Assessing Exposure: BSI Suggests manufacturers gather nano-exposure information including estimates of exposure and dose by pathway, both for individuals and for concerned populations. To help compile this information, BSI encourages companies to answer the following questions: What are the tasks where people can be exposed to nanoparticles?; Who can be exposed during each task?; What are the potential routes of human exposure?; What are the chances of exposure occurring?; What are the levels of potential exposure?; Can the nanomaterials be present in ambient air or on surface or other potential exposure locations?; and Which control measures can be successfully applied to each task? BSI indicates it is likely that existing exposure information will be insufficient; and accordingly, as EHS uncertainty increases, caution should also increase.
Control of Exposure: BSI advocates the following hierarchy of exposure controls: (1) eliminate exposure; (2) substitute materials to reduce/prevent exposure; (3) enclose manufacturing process; (4) use engineering controls; (5) implement procedural controls; and (6) have workers use personal protective equipment (BSI notes this should be the last option). Again, this hierarchy is not unique to nanomaterial exposure control.
Suggested Benchmark Exposure Levels: Importantly, BSI recommends the following extrapolated nanomaterial exposure levels:
- Fibrous nanomaterials = 0.01 fibres/ml (where a fibre = 3:1 aspect ratio; length greater than 500 nm ).
- CMAR nanomaterials = 0.1 x existing material workplace exposure limit for bulk counterpart.
- Insoluble nanomaterials = 0.666 x existing material workplace exposure limit for bulk counterpart.
- Soluble nanomaterials = 0.5 x existing material workplace exposure limit for bulk counterpart.
Health Surveillance: In keeping with recent statements by NIOSH, BSI also appatently believes that "currently, no specific measurable health effects have been uniquely associated with exposure to nanomaterials . . . This would suggest that medical surveillance is not appropriate at this point in time."
Accidental releases: BSI believes it is essential that all employers have documented policies and procedures in place for accidental releases of nanomaterials. These procedures should be consistent with the level of hazard and quantity of nanomaterial involved in the spill. BSI also believes manufacturers should cleanup spills in a manner that produces the least amount of potential exposure for workers, and recommends thorough dissemination of information; instruction; training; PPEs to be worn by workers; and written guidance on safe disposal of waste. In the event of an accidental spill of nanomaterials, BSI suggests roping off the effected area, reducing likely spread from effected area, wet wiping the spill or using HEPA vacuums, avoiding dry sweeping;; and implementation of evacuation procedures if necessary. Again, none of these are unique to nanomaterials.
Disposal procedures: BSI believes specific disposal plans for nanomaterials should be developed based on both U.S. Department of Energy (DOE 2007) and UK Environmental Agency Guidance (HWROI) existing documents. Any plan for storage and disposal of nanowastes should be developed taking into account of the hazardous nature of materials and quantities. Nanowaste should be separated and disposed of separately from regular waste.
Storage prior to disposal:
BSI recommends the storage of nanowaste itself in containers adequate to prevent escape and the proper labeling of such containers, and further calls for the storage of nano-contaminated items in sealed plastic bags.
Disposal: Regarding disposal of nanowastes, BSI believes "[i]t is a reasonable worst case assumption to consider all nanomaterial waste as potentially hazardous. It can therefore be disposed of as chemical waste." To this end, BSI believes manufacturers should follow UK’s List of 2005 Waster Regulations regarding disposal of chemical wastes.