The Macquarie Dictionary defines a risk as "exposure to the chance of injury or loss". 

In a kitchen, when a knife is properly used, for the purpose for which it has been designed, by someone who knows how to use it, there is very little chance of injury. The risk is low. 

On the other hand, if the knife is carelessly or improperly used by an untrained person, the risk of injury is high. 

If a cutting board is kept clean and in good condition, the risk of infection from salmonella and other bacteria is low.   

If  kitchen hygiene is poor, the risk of infection is high. 

The level of risk depends on the way the situation is managed. 

You should know about the hazards in your workplace.   

Some will pose a real threat to health and safety; others will be relatively low risk. 

If necessary, you must do your part  to reduce the exposure of everyone in your workplace to the chance of injury; i.e. you must help control the risk, either by eliminating it, or reducing it to an acceptable level.