Upton Sinclair's The Jungle
Upton Sinclair's expose of the American meatpacking industry is largely to thank for the massive drop in cases of gastroenteritis (and rise of vegetarianism) around the dawn of the 20th century. When the book was published, the public, pretty keen on taking solid shits, was outraged by the novel's accurate depictions of the unsanitary conditions in slaughterhouses and lack of regulations forbidding the practice of shoveling week-old entrails off the floor along with the cow shit and calling it sausage.
President Teddy Roosevelt took action as a result, leading to the Pure Food and Drug Act, the Meat Inspection Act and eventually the FDA, despite getting his meat primarily from large game he beat to death with a club (probably).
What it's really about:
It wasn't about sanitation or meat safety. Sinclair was actually trying to expose the exploitation of American factory workers and convert Americans to socialism.
He went undercover for several weeks as a meat packer and not only saw that working conditions in meat-packing factories at the time were horribly unsafe, but that there was massive corruption within the upper levels of management. The stockyards exploited not only the common man, but also the common women and children, who worked the same lengthy shifts and lost the same useful appendages to machinery without proper safeguards. At one point in the book, an employee accidentally falls inside a giant meat grinder and is later sold as lard.
A pinch of Mitch in every bite.
But much to Sinclair's frustration, the public's reaction was less "that poor exploited worker!" and more "HOLY SHIT THERE MIGHT BE PEOPLE IN MY LARD." They read right past the hardship of the workers and focused entirely on how gross the meat-packing process was.