The bamboo is heat treated to carbonise the surface of the bamboo, giving it a quality finish and good service life. The carbonisation finishing process provides water resistance and prevents the growth of microbes (bacteria and moulds) during normal use. The bristles are made from a BPA Free polymer resistant to microbial growth during normal use, to ensure safety and durability.Made from bamboo, a natural cellulose fibre, the handles are biodegradable, environmentally sustainable, and they do not pollute the environment. The amazing growth and self-renewing ability of bamboo means that deforestation is not necessary either. Even the packaging is bio-degradable. The bamboo handle will biodegrade into soil without pollution, we suggest that you remove the bristles and place them into the bin or recycling.Rinse and dry after use.