Bamboo toothbrush Extra Soft   The 'Bamboo' bamboo toothbrush has natural, extra soft, straight-trimmed bamboo based bristles for the efficient cleaning of extra sensitive teeth and gums.  MATERIALS The bristles are made from bamboo dust mixed with nylon 4 - approximately 90% bamboo, 10% nylon. Nylon 4 is a BPA and phthalate free, naturally biodegradable polyamide and is widely considered as one of the most tolerable plastics from a health point of view.