According to Rodale News, expert Dean O. Cliver, PhD from University of California, Davis, conducted research on the subject and found that wood cutting boards contained less salmonella bacteria than plastic. On wood cutting boards, the bacteria sank “down beneath the surface of the cutting board, where they didn’t multiply and eventually died off.” On plastic boards, however, bacteria got caught in knife grooves that were near impossible to clean out, whether the board was washed by hand or dishwasher. So while sparkling new plastic cutting boards might be easy to disinfect, any weathered plastic board will hold onto bacteria.