dangerousIt's dangerous to walk alone in the woods at night.
unsafeDon't play in the street - it's unsafe.
hazardousHeavy rain is causing hazardous driving conditions.
treacherousIce had made the roads treacherous.
harmfulPlease be aware that these chemicals are harmful to human health.
lethalThese medications can be lethal if they get into the wrong hands.
deadlyBelladonna can be made into a deadly poison.
riskySurgery at his age would be too risky.