peril-n; 2 Senses

Sense Number 1: a cause or agent of danger, a hazard

Commentary: PERIL[+cause][+effective][+danger] [+relation][+role][+agent][+danger]
NOTE: 'peril' occurs as object/subject, not in a prepositional phrase
NOTE: refers to something that is the source, cause of danger

Many studies have concluded that smoking is a peril to your health.
She first experienced the perils of stardom a decade ago.
The recent assassination poses a peril to future negotiations.

WordNet 3.0 Sense Numbers: 1, 3

Sense Number 2: being in a state of exposure to danger

Commentary: PERIL[+state][+exposure][+danger]
NOTE: 'peril' occurs with preposition, 'at peril' 'in peril'
NOTE: refers to a potential dangerous state of something/someone

Swim on that beach at your own peril.
This political movement is in peril of dying.
The weak dam has put the city in peril of a flood.

WordNet 3.0 Sense Numbers: 2