"The Jungle" by Upton Sinclair
Was the inspiration and motivation
President Theodore Roosevelt needed to create the food reforms after seeing the damage in the food and drug industry. He brought in Sinclair to tell him more about the problem.
Sinclair went into a factory and saw the process first hand as one of the workers and explained it all to Roosevelt who was disgusted by what he heard.
Most medicines and drugs were mostly made of poisonous products at the time and there was no "warning label" to tell people what exactly what they are taking. They only know a doctor prescribed it so they have to take it, which led to some very deadly outcomes.
Was inspected to make sure it was 100% the meat the label said it was since most of the meat was NOT an animal meant for slaughter or there would be body parts since some of the workers got injured or had their fingers cut off. The pieces of fingers were tossed into the processed meat and passed as "an animal" that was slaughtered.