The evidence came from experiments—and from a wider food-safety crisis
The federal case against some food preservatives did not rest on a single dramatic discovery. At the Department of Agriculture, chemist Harvey Wiley organized controlled feeding trials known as the Poison Squad. Volunteers ate ordinary meals containing measured amounts of additives such as borax, while researchers monitored their health. The trials gave officials evidence to argue that chemicals used to keep food looking fresh or lasting longer could harm people at certain doses.
That evidence mattered because preservatives were part of a larger problem: consumers often could not tell what was in processed food, and some products were adulterated or misleadingly labeled. Wiley and other reformers pushed for national rules that would let the government challenge harmful ingredients and false claims.
What the 1906 law actually did
Public outrage over food production helped build support for action. Upton Sinclair’s The Jungle drew attention to filthy conditions in meatpacking plants, although the book was not primarily about preservatives. In 1906, Congress passed both the Pure Food and Drugs Act and a separate meat-inspection law.
The Pure Food and Drugs Act barred interstate commerce in foods and medicines that were adulterated or misbranded. It did not declare every preservative dangerous, nor did it create today’s FDA under that name. Instead, it gave the Agriculture Department’s Bureau of Chemistry a role in enforcing federal food and drug standards; that agency later developed into the FDA.
The important shift was from relying on buyers to detect hidden ingredients to giving the government authority to investigate and act. Wiley’s experiments helped make the risks tangible, while the law addressed the broader failure that made those risks hard for the public to see: a food could look wholesome even when its contents or label were not.
