Of course biological weapons have been around for years. Sometimes accidents happen. Here's one from Spain. There was also something similar in Mexico.

"An alternative theory blames an accident involving biological weapons at the US air base at Torrejon, just outside Madrid. It has been suggested that the doctored rapeseed oil was a convenient myth to protect Spain’s burgeoning agro-industry or military interests."

https:// www.cdc.gov/mmwr/preview/mmwrhtml/00000211.htm

http:// pubmedcentralcanada.ca/pmcc/articles/PMC1506574/pdf/bmjcred00671-0032.pdf

https:// devastatingdisasters.com/spanish-toxic-oil-syndrome-1981/