Water Contamination

noun a highly toxic metallic element that is used in various industrial processes and is a common cause of poisoning

• Arsenic is a highly toxic chemical element often used in pesticides.
• I heard that arsenic was found in the water supply.
• Don't eat that fish, it's probably full of arsenic!
• His words were like arsenic, poisoning the atmosphere of the room.

adjective not processed or dealt with in any way; not treated with a particular substance or process

• Untreated mental health issues can have serious consequences.
• If you leave your cut untreated, it could get infected.
• I can't believe you're leaving that toothache untreated, dude.
• His untreated anger festered and eventually led to an explosive outburst.