The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

It's TOXIC in small doses.
Breaking Bad Season 2, Episode 1

-It's just water.
-Yes, TOXIC water.
Money Heist Season 3, Episode 4

Now it is.
Finally, hot water.
No more TOXIC waste.
Breaking Bad Season 2, Episode 10

I think our relationship
has become TOXIC.
The Big Bang Theory Season 11, Episode 11

All right. The EPA can cite him
under the Toxic Substances...
Breaking Bad Season 4, Episode 3