eli5: There are labels on certain products saying “x product was produced in the same factory as y product” where y product contains an allergen. Why does it matter that both products were made in the same factory?

Question

eli5: There are labels on certain products saying “x product was produced in the same factory as y product” where y product contains an allergen. Why does it matter that both products were made in the same factory?

In: 0

Answer 1

Certain ingredients might cause enough dust in the air that it could affect somebody with severe allergies… like the dust from opening a 100 pound sack of peanuts and dumping it into a hopper to make Snickers might waft over to the vat of chocolate being poured over Milky Ways and even tiny amounts of dust might affect somebody. Or Snickers and Milky Ways might get run through the same packaging line. Even microscopic amounts of cross-contamination can affect some people.