I believe the concept of as far as possible is meant to be vague. It isn’t defined as a certain level of safety or risk mitigation. Because by defining the point at which risk is “adequately” mitigated would lead to the requirement being met, but just barely. I believe the concept of as far as possible is meant to be a challenge and a charge to any company to do everything they can within their power to create a device with as low a possibility of risk or harm to its users as possible.