More than a century ago, enterprising manufacturers added brand-new chemical preservatives into food to keep it fresh as it traveled from the farm into rapidly growing American cities. Milk no longer went rancid! Meat no longer spoiled! But some scientists wondered: Could all these preservatives be doing more harm than good? It took a crusading chemist named Harvey Washington Wiley to take this fight all the way to Washington, D.C., where he recruited a “poison squad” to test their health effects—and, in the process, created the nation’s first law to protect against poisons in our food supply. But did he succeed? Are the preservatives we eat today safe? Listen to this episode to hear Wiley’s story—and learn why some of the chemicals he tested are still in our food today.

In the late 1800s, America was changing rapidly, and so were its food systems. The country was industrializing, and as people moved into cities in search of jobs, they no longer picked their own tomatoes or churned their own butter from the milk of local cows. Food had to travel farther to reach these city dwellers, and, in an era before artificial refrigeration, it spoiled quickly. But there was a solution, and it came from scientists working in the exciting new field of chemistry: preservatives that promised to keep food fresh for days, even weeks. By the 1880s and ’90s, Americans were consuming preservatives such as formaldehyde, borax, and salicylic acid for breakfast, lunch, and dinner.