Monday, June 28, 2010

British Report Laments Lack of Exposure Data on Carbon NanoTubes

The UK Department for Environment, Food and Rural Affairs (DEFRA) has issued a report arguing that there is an almost total lack of exposure data for carbon nanotubes (CNT) present in consumer products. The report "A Lifecycle Assessment Study of the Route and Extent of Human Exposure via Inhalation for Commercially Available Products and Applications Containing Carbon Nanotubes," was conducted by the Safety of nanomaterial Interdisciplinary Research Centre (SnIRC), with participation of other Academic and Industrial Experts.

As part of the study, "a review of all available CNT-containing products was carried out, and a representative subset of the products was identified for exposure analysis." The selected CNT-containing products were lithium-ion batteries, epoxy adhesive resins, and textiles. The study "assessed the suitability of current lifecycle assessment (LCA) protocols for assessing inhalation exposure from CNT and other nano-products."

The findings of the study indicate that:

* LCA is not a tool for exposure assessment. On the contrary, exposure assessments can provide information to LCA that is relevant for impact assessment of CNT releases. LCA is, however, useful in identifying the stages in the lifecycle during which exposure may be relevant.

* There is an almost complete lack of data to enable both a full-scale LCA, or a quantitative exposure assessment. Due to unavailability of the required data, a simplified LCA approach was adopted in this study, focusing on the potential inhalation exposure during the lifecycle of the selected CNT-containing products. Also, the exposure assessment was limited to qualitative analysis because of the lack
of data necessary for a quantitative assessment.

Furthermore, "both LCA and exposure analysis have shown that the material synthesis stage is prone to giving rise to inhalation exposure to CNTs. However, the few studies carried out so far have generally shown that nanoparticle emissions during synthesis can be effectively controlled through appropriate engineering measures. Significant inhalation exposure to CNT material at this stage should be preventable provided such processes are carried out under appropriate emission control and waste management procedures."

Therefore, the study concludes that "the main emphasis from the exposure point of view...needs to be on other stages/processes in the lifecycle of products, where any sophisticated emission control measures are not likely to exist." They specifically suggest as examples "postproduction handling, transportation, accidental release, and use and disposal of the relevant materials and products."

No comments: