Significance Silver nanowires are a type of novel fiber that are likely to have wide application in consumer electronics but that can also carry risk for cell internalization and toxicity. Here, we show that silver nanowire toxicity can be greatly diminished by reducing nanowire diameter without affecting device performance. X-ray microscopy and supporting studies revealed that endolysosome membranes can mechanically crumple thin silver nanowires, the likely mechanism for diminishing toxicity.