Influence of realistic wearing on the morphology and release of silver nanomaterials from textiles†
The recent commercialisation of antimicrobial textiles has resulted in concern regarding the incidental release of silver nanomaterials (Ag-NMs) to the environment. To date, studies have measured Ag-NMs released from unworn textiles under simulated conditions, but little is known of Ag-NMs released under actual wearing conditions. Our experiments were conducted for three cycles of wearing and washing, where the textiles (socks) were worn for a similar distance under walking or running scenarios. The effect of wearing was assessed through characterization of both the fibres and the Ag-NMs released into the wash water. Ag released into the wash water was ∼2–3× higher for the running and walking trial respectively compared to the unworn control during the 1st cycle. Silver releases in the 2nd and 3rd cycles were similar for the walking trial and the unworn control, but lower for the running trial. A 29% decrease in silver content was observed on the socks used for walking after the 3rd cycle. Silver in the wash water was mainly particulates (≥92%; particles >1–2 nm) and wearing created a higher number of smaller sized particles (∼50 to 100 nm). Imaging of the Ag-NMs revealed that 54% of the particles surveyed were micrometer size silver sheet-like structures, but with an estimated thickness of only 67 ± 56 nm. This data set can serve as a reference for the development of artificial wearing methodologies into the future. The Ag-NM sheet-like structures identified here require further study as their fate, transport and toxicological properties will be different to those of their pristine and/or spherical counterparts.