Surströmming is the fish equivilent of wine  but not risking to be "2nd" went the extra mile resulting in being indiscriminatly and indefenitly branded as the first large scale deployed biological weapon.
Ever since the Medieval period this has been the veapon of choice for egocentrik sociofobic and/or hillbillys living in Sweden who evidently lost the ability to smell through backwards evolution. Early deployment in what is now called "Norrland" resulted in catastrophic contamination of the entire "state" (ofsort) where now only lives 4 people per square mile. 
Estamations are around 1-2 people per square mile in the disaster zones leaving scientists who has studied the potential weapon capabilitys of this substance deciding the "red zone" or "area of total annihilation for any normal homosapiens" is a 0,5 mile wide, 1 mile long rectangular area starting from the point of first opening of can to 1 mile downwind. Currently more extensive research is being conducted and early results are promising.
The initial impact on the population (around 20 people per square mile) was devastating with most people taking suicide before even trying to figure out what it was when the first cans were opened by curious buyers, none wich survived the first encounter with the new product. Goverment was slow in recognizing this new public threat but unluckily someone did. Its unclear when the accidents of curious consumers evolved into terrorist attacks by inhumane backward evolved "monkey-men" that lost the ability of there nostrils possibly due to them being dipped either in schnapps and/or other substances then quickly dipped in snow  this can in rare cases result in the nose immigrateing and serious medical issues.
By the year 1450 the rebelious group de bruterhood  had managed to establish a first few "Permanent Red zones" nearly wiping out entire comunitys before they could escape. Deaths were piling up in the millions and Norway rejected Swedish rule in fear that the "Surströmming" would carry over to Norwegian soil.
States were erased from the face of the map and left was a void of hillbillys casually munching "Surströmming". Debaters up to this day argues about whether or not they were even aware of what they did but the damage is obvious, thousands of miles of land is now abandoned with millions of lives clamied and most of Norrland has turned into a hazzardous zones.
- Stored away until old as hell and wait till its unrecongisable so you won't realise it's actually rotten fish and not something ells.
- Not takin into account the "pure" zones where small villages of much denser populations has survived by banning all fish untill further notice and thereby sevearly affected the real numbers.
- Cause usually traced to person in question slipping and falling into the snow.
- The brotherhood, but they had problems pronauncing it with the genetic defects from incest and the fact that they ARE hillbillys without much education.