Milk
The early Victorians consumed milk in its raw state, meaning it was not pasteurized, a process introduced by Louis Pasteur to help lengthen the shelf life of beer. Refrigeration was iffy, there was no way to ensure milk was kept cool from dairy to home, and shelf life was very short. Another issue, largely unknown to the Victorians, was that milk is an excellent choice as a microbial growth medium.
Victorians did know when the milk they had at home was beginning to slide past its best use date. It smelled and tasted sour. A leading home management authority of the day, Isabella Beeton, advised the addition of boric acid to slightly off milk, to both remove the sour taste and smell. Her readers were assured that the addition of small amounts of boric acid would do no harm and encourage consumption of the milk. Mrs. Beeton was twice wrong.
Boric acid when consumed even in small amounts caused (and causes) digestive issues including diarrhea, vomiting, severe cramps, and abdominal pain. While none of those is usually regarded as a fatal symptom, except in children who were the leading consumers of milk, it was that the boric acid concealed the fact that the milk was bad that made it poisonous.
Raw milk can contain tuberculosis, diphtheria, brucellosis and scarlet fever. It also contains or can contain staphylococcus, listeria, e-coli, salmonella, and many other bacteria. As mentioned, milk is an excellent medium for the growing of microbes, and masking the fact that unpasteurized milk was no longer fit for consumption was deadly – particularly for children.
Controlled use of alum is allowed today in some prepared foods, such as commercially prepared pickles. Chalk is used in many grocery store white breads for the reason that it helps make the bread a brighter white. It’s found in the ingredients as magnesium carbonate or calcium carbonate. But it won’t be found at levels which lead to malnutrition.