Final answer:
The first concern for a first aid provider when a coworker has amputated his thumb is to assess the patient for any life-threatening conditions. Controlling bleeding and stabilizing the patient take precedence over finding the amputated part or applying a tourniquet, which is only used if bleeding is severe.
Step-by-step explanation:
If a coworker just amputated his thumb in a cutting press, my first concern as a first aid provider would be B) Assessing the patient for life-threatening conditions. Before addressing the amputation directly, it is critical to ensure that the patient is not facing any other more immediate risks such as severe bleeding that could lead to shock, or other injuries. Once life-threatening conditions are ruled out or managed, you can then proceed to control bleeding with direct pressure. While finding the amputated part is important, it is secondary to ensuring the patient's overall stability. A tourniquet might be necessary if there is heavy bleeding that cannot be controlled with direct pressure. However, getting others to help you immediately can be beneficial in managing the situation effectively and quickly. Ideally, you would direct someone to call emergency services while you attend to the patient.