In 1820, chemist Friedrich Accum published "A Treatise on Adulterations of Food and Culinary Poisons" revealed the extent of toxic food colourings, especially in sweets and confectionery. His treatise describes how manufacturers routinely used mercury-containing vermilion, red and white lead, copper-containing blue vitriol or verdigris and Scheele’s green which contains arsenic and copper.
According to Burrows, it was widely known at the time that these food colours were toxic, and there were often dangerous consequences. In 1851, 17 people died in Britain after eating coloured lozenges.
With foods increasingly put under the microscope, the first modern regulations were passed to protect consumers. Denmark listed colours permitted for food colouring in 1836, the UK saw the Food Adulteration Act writ into law in 1860 while Germany banned harmful additives with its Colour Act of 1887.