The site was used for the disposal of toxic waste.
noxious [usually before noun] formalnoxious substances and gases are poisonous
Vehicles pollute the air with noxious fumes
The soil may be contaminated with noxious substances.
hazardous [usually before noun]hazardous substances are likely to harm people, animals, or the environment if they are not dealt with or got rid of carefully
Lead is one of the most hazardous substances known, causing cancer and nerve damage.
The building is now unoccupied, and all radioactive or hazardous materials have been removed.
hazardous nuclear waste
deadly extremely poisonous and likely to kill you – used especially about poisons and snakes
poisonous snake• By the way, I don't keep any poisonous snakes.• The KingCobra, or Hamadryad, is the largest of all poisonous snakes.• While on a mission, Paul was bitten by a poisonous snake.• Many of the animals are hostile to humans: for example, poisonous snakes and fiercemountain cats.• In popularmythologypoisonous snakes are always ready and waiting for the chance to strike out and kill their attackers.• RubyWax found some realwackos in West Virginia-loons who use poisonous snakes in religiousceremonies.• The poisonous snakesinvite a certaindeference, and the rattlesnake is even canned occasionally for human consumption.• The air is filled with a dingo's howl, the footpaths alive with the poisonous snakes on their slithering nocturnal hunt.