In major US cities in the late 19th century, dairy producers looking to cut costs would dilute milk using pond water.

The resulting greyish tinge would be corrected with a dose of plaster dust, and some yellow lead to give a golden hue.

Replacing the cream, which had been skimmed off, was nothing less than pureed calf brains.

Once the manufacturer was satisfied with the aesthetic of the product, the toxic chemical formaldehyde could be added to give the so-called "embalmed milk" a longer shelf life.

A depiction of Death making candy tainted with arsenic and plaster of Paris. ( Getty: Harper's Weekly )

Milk was only one of a long list of commonly adulterated foods that included lead in cheese, brick dust in cinnamon, sawdust in ground coffee, and brown sugar spiked with crushed insects.

In the zenith of industrial capitalism, poor workers migrating to urban centres became golden geese for profit-hungry food manufacturers.

That was until a preacher's son, Harvey Washington Wiley, dedicated his life to taming the seemingly untameable industry.

Wiley — with his 'poison squad' and a very peculiar experiment — gained international recognition for his role in the creation of legal food standards.

The 'unregulated Wild West' of food production

As the industrial revolution was applied to food processing, manufacturers rushed to embrace the rise of industrial chemistry and were knowingly selling harmful products.

Unchecked by government regulation, basic safety or even labelling requirements, they put profit before the health of their customers.

The target market for these adulterated products was the blue-collar workers, who were migrating to cities from rural areas and farm towns — and were desperately trying to stretch a dollar.

"There were no labels, and so there was no public pressure," said Pulitzer Prize-winning science journalist Deborah Blum, who has written a book on Wiley.

"It was just a pre-regulatory Wild West of food that permitted bad actors to do what they will, and so they did."

Sorry, this audio has expired Listen to the interview with Deborah Blum

Wiley was the son of a southern Indianan famer who worked on the Underground Railroad that helped escaped slaves seek refuge in the north.

After briefly serving in the Civil War, Wiley became a chemistry professor, and in 1883 was named the Department of Agriculture's chief chemist.

The department, traditionally concerned with agribusiness, became the vehicle for his 30-year campaign for safe food and proper labelling.

Wiley's crusade was part of a larger Progressive movement which fought against the monopolies and government corruption that had accumulated throughout the 19th century.

The Progressive Era The Progressive Era was a period of widespread social activism and political reform across the United States

The Progressive Era was a period of widespread social activism and political reform across the United States The main objectives of the Progressive movement were eliminating problems caused by industrialisation, urbanisation, immigration, and corruption in government

The main objectives of the Progressive movement were eliminating problems caused by industrialisation, urbanisation, immigration, and corruption in government It spanned from the 1890s to the 1920s, led by social activists and 'muckraker' journalists

Already alarmed at food adulteration, he delivered speeches and wrote popular articles, working closely with 'muckraking' journalists and the burgeoning pure food movement.

"He came in with this kind of moral crusade, Holy Roller attitude. He was determined to make a difference," Blum said.

The poison squad and an unusual experiment

In response to Wiley's growing public profile, the Food Manufacturers Association was set up to represent the interests of industry.

Misleading articles by non-existent journalists were circulated to harm his reputation while sympathetic allies were planted within the US government.

President Theodore Roosevelt, the progressive crusader famous for reigning in the octopus-like monopolies of the era, was not as forward thinking when it came to food regulation.

According to Blum, Roosevelt was often working with food businesses to make sure that his anti-monopoly regulations didn't affect their income streams too drastically.

"Roosevelt would create secret boards to countermand some of his ideas and rulings as they try to get the law in place, and literally working with people who weaken the regulations," she said.

Theodore Roosevelt is remembered as a crusader of the Progressive Era ( Getty: Hulton Archive )

Despite his capacity as a writer and orator, it would not be Wiley's advocacy that would cause the government to change its mind.

Rather, it was a particularly unusual experiment.

At the dawn of the 20th century, Wiley invited young clerks at the Department of Agriculture to eat three free meals a day cooked by a professional chef using farm-fresh ingredients.

The group, soon to be known as the 'poison squad', were asked to fine dine in the basement below the department's offices every day for a year, their diet strictly limited to these meals.

The members of Wiley's 'Poison Squad' were assessed for their health and respectability before being invited to join. ( Flickr: US Food and Drug Administration )

There was a catch.

Half of the perfectly prepared dishes in this makeshift kitchen were deliberately spiked with doses of suspected food additives — industrial chemicals like borax or salicylic acid.

In an act of bravery, the volunteers knowingly subjected themselves to poisoning in the name of science.

Not surprisingly, these various additives caused a host of health woes for the unlucky half including nausea, diarrhoea, vomiting, liver damage, kidney damage, and jaundice.

While lobbyists could suppress Wiley's findings, they couldn't control newspapers, which zealously relayed information about the group to a public that slowly elevated Wiley to a hero status.

These idealistic volunteers embraced this motto on a sign in their special dining room — "none but the brave can eat the fare." ( Flickr: US Food and Drug Administration )

As awareness about food contents spread, an explosive novel called The Jungle was published by socialist writer Upton Sinclair in 1906.

It documented the life of immigrant meatpacking workers in the packing houses of Chicago, where "rats, poisoned bread, and meat" would end up mixed in the same food processor. The book sparked consumer fury.

The government's hand was forced, and the Meat Inspection Act was passed with Roosevelt's full support, followed a week later by the Pure Food and Drug Act.

Commonly known as 'the Wiley Act', it required that a drug's active ingredients be written on its packaging, and meant unsafe products could be outlawed.

"The Pure Food and Drug Act meant now for the first time in American history you have the entry of consumer protection in law," Blum said.

Gradually food safety standards were expanded and exported internationally and by mid-century became the rule rather than the exception throughout the developed world.

Consumers today, who value their breakfast free of borax, have Wiley to thank.