1900 English beer poisoning
In 1900, more than 6,000 people in England were poisoned by arsenic-tainted beer, with more than 70 of the affected dying as a result. The food safety crisis was caused by arsenic entering the supply chain through impure sugar which had been made with contaminated sulphuric acid.
Source: Wikipedia — 1900 English beer poisoning (CC BY-SA 4.0)