Final answer:
The statement highlights the health hazards of hat-making due to the use of mercury, which is a poisonous substance. Workers in various industries during the Industrial Revolution faced numerous health risks and safety hazards.
Step-by-step explanation:
The statement that making hats was once a dangerous enterprise because of the use of mercury highlights the health hazards of hat-making. Hatters who worked with mercury in the process of making felt would breathe in mercury fumes, which is a poisonous substance. This posed a significant risk to their health and safety.
The use of mercury in hat-making is just one example of the hazardous working conditions that prevailed in factories during the Industrial Revolution. Workers in various industries faced numerous health risks and safety hazards, leading to injuries, disabilities, and even death.