“disease bacteria … were not recoverable from wooden surfaces in a short time after they were applied, unless very large numbers were used. Wooden boards that had been used and had many knife cuts acted almost the same as new wood, whereas plastic surfaces that were knife-scarred were impossible to clean and disinfect manually …” read the report here
Interestingly Professor Cliver cites an unconnected study in California of sporadic salmonellosis which included cutting boards among many risk factors by Professor Philip Class. It revealed that those using wooden cutting boards in their home kitchens were less than half as likely as average to contract salmonellosis, those using synthetic (plastic or glass) cutting boards were about twice as likely as average to contract salmonellosis.
This is as far as I can find the only academic research comparing wood and other materials, the results clearly say a new plastic board works well as does a new or old wooden board, the real dangerous one is a plastic board with cuts in it, which of course they all have once you have used them. So if you inevitably have cuts in the board sensible advice would be to use wood? well no current advice is as soon as your board has cuts throw it ways and get a new one.
UK Food Standards Agency link
“True or false? Plastic chopping boards are more hygienic than wooden ones.
False – it’s a myth
There isn’t any strong evidence that one type of chopping
board is more or less hygienic than another, whether plastic,
wooden, glass or even marble. What is important is that
the board gets cleaned properly after every use and is
replaced if it gets damaged, for example from deep cuts or
scoring. You could also use separate chopping boards for
raw and ready-to-eat foods.“
Food safety authority of Ireland link
“Wooden chopping boards can be used for food preparation once they are kept in a clean and hygienic condition. Generally, all surfaces which come in contact with food must be of sound condition and be easy to clean and where necessary disinfect. They must be made of smooth, washable, corrosion resistant and non-toxic material. Chopping boards must be constructed in a way that will minimize the risk of contamination. They must be kept in a good state of repair.
Whether wooden or plastic chopping boards are used it is essential that they are in good condition. Deeply scored chopping boards are more difficult to clean and can harbour harmful microorganisms which can contaminate food. They should be re-planed or if this is not an option they should be thrown away and replaced by new boards.”