I made a diluted solution of hydrogen cyanide at home and threw it out my backyard.
Why did you throw it outside?
To have a good reason to kill a mouse
Getting rid of pests is sometimes necessary but throwing the poison outside is not good. You could have hurt a person or somebody's pet if they got into the poison.
I designed the poison to be harmless unless you ingest it or you rub it in your eyes. I can't help it if an innocent being comes along and tries it.
Poison is still poison, no matter what you can help. You actually can help by not throwing it outside randomly regardless of the mouse population. Be more mindful of other creatures coming into contact with it, it happens too often.