ISO 14001 is about an environmental management system (EMS). So, risk assessment in ISO 14001 is related with desired or undesired results about the EMS.
In a laboratory you can start by determining environmental aspects and impacts generated by laboratory operation. Then, you can determine if there are any risks and opportunities around those environmental aspects and impacts. For example, I worked in a laboratory that generated hazardous wastes. Risks could be about giving the right treatment for those wastes, working with the authorized waste operators, using practices to minimize waste generation, minimizing wastes mixture.