I am surprised to hear as well that instructions for use (IFU) and labels are deemed as the least effective way to solve residual risk since the amount of effort that is taken to ensure the content on the packaging and labeling meets regulatory requirements. Regulatory and quality are heavily involved in the artwork approval process for packaging and labeling content- which can go into several rounds of review and approval to meet all market regulatory and quality requirements. Aside from the IFU, another method for resolving residual risk can be done through reviewing the risk assessment and setting up sufficient customer service and preventative actions for anticipated customer complaints such as customer misuse. For example with the IFU, certain labeling on the product can help identify the market, product type, and product model to help customer service properly address any customer complaints and prevent or resolve risk associated situations. There will also be customer service training in place for the customer service representatives and there will be customer service bulletins created for any anticipated customer complaints to ensure they are handled effectively and with the most care. Unfortunately, as mentioned by sin3, some of the residual risk is indirectly associated with the company and directly with the misuse of the user, even if all preventions are taken to ensure proper use.