I wondered so I sought out input from three experts and this is what they had to say:
“Once your cutting board becomes excessively worn or develops hard-to-clean grooves, replace them. These grooves can harbor harmful bacteria that even careful washing will not eliminate. So when you see those grooves, it’s probably time to purchase a new cutting board.” Diane Van, manager of the USDA Meat and Poultry Hotline
“Once cutting boards start to look grungy, it’s probably time to replace them. Of course, “grungy” is relative, so go with your instinct.” Marion Nestle, food safety expert
“Discard boards once they sustain cracks and cuts that can form a hiding place for raw food and bacteria, making them harder to clean completely.” Mariette Mifflin, houseware/appliance expert
Looks like I'll be replacing my cutting board soon. I've heard lots of good things about the OXO brand cutting boards so will be on the lookout for an OXO.
In 2003, Laura Bruzas founded Healthy Dining Chicago to offer practical information and valuable resources to help time-pressed consumers make informed choices that are kind to Mother Earth and all of her inhabitants. Follow on Twitter @HealthyDiningIL to get a free tip a day.