A wooden cutting board is often used to cut meat, fish, vegetables, fruit, cheese and a million and one other things. Sharp knives are used that cut grooves into the wood, creating an ideal breeding ground for all sorts of different bacteria.
Mere washing in the sink with soap and hot water is usually not sufficient to keep cutting boards clean. Not only do they have to be washed in between preparing different foodstuffs on them, but they need to be given a sound bleaching every few days. After bleaching it (one part bleach to five parts water), it must be properly scrubbed using hot water and then left to airdry. Wooden boards can also be sterilised by putting them into the microwave oven for ten minutes on high, but this does not work for plastic, as the surfaces do not get hot enough to kill the germs.