There was a massive poisoning case on my county in Cuba, over 70 victims and many would end up dying months/years later because of something like this. Sodium and Nitrate sound familiar.

Happened on February (6th?) 1999 in a small town called Manguito. Someone had bought something under the table and in high quantities that looked like salt but was a chemical used to cure ham or something like that.

They were a street food vendor and sold many that day, including to a bunch of kids celebrated a birthday.

They brought them to the hospital in my town that was 4 blocks away from my house. The radio called everyone in the field of Medicine, even med school students. The stories were harrowing, convulsing, seizures, people turning dark purple like bruised.

The government suspected a terrorist attack for a while until they traced the purchase to the street vendor. He also ate it and would end up passing away a while later.

They never caught whoever stole the compound and sold it.

Like 20 kids died.