This study aimed at analysing the likely route and extent of human exposure to carbon nanotubes (CNTs) via inhalation for a set of representative CNT-containing products in a lifecycle perspective.
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 three CNT-containing products selected for the study included lithium-ion batteries, epoxy adhesive resins, and textiles.
In the course of the study, the authors assessed the suitability of current lifecycle assessment (LCA) protocols for assessing inhalation exposure from CNT and other nano-products. The relevance and adequacy of the relevant ISO protocols was assessed in relation to nanotechnology products (especially CNT-containing products), and any inadequacies have been highlighted; possibility of exposure to CNTs arising via inhalation during all stages of the life cycles of the selected study products were also analysed.
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.
- Both LCA and exposure analysis have shown that the material synthesis stage (both for CNT materials, and CNT-containing products) 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. The main emphasis from the exposure point of view, therefore, needs to be on other stages/ processes in the lifecycle of products, where any sophisticated emission control measures are not likely to exist, e.g. post-production handling, transportation, accidental release, and use and disposal of the relevant materials and products.
- A brief summary of different lifecycle stages of CNT-containing batteries, textiles, and epoxy adhesive resin is shown in Table 1. Using the currently available level of scientific evidence, those stages in the lifecycle of each study product have been highlighted where inhalation exposure to CNT is possible.
Follow this link to download the full report: 'A Lifecycle Assessment Study Of The Route And Extent Of Human Exposure Via Inhalation For Commercially Available Products And Applications Containing Carbon Nanotubes'.