When they began losing, it proved toxic for an older team with little to play for.

All subjects died, including those given the berkatit, which proved toxic.

A few cancer experts say the treatment has proved too toxic and too ineffective to use.

Hate to think we stopped trying to figure out ways to clean up the water because cleaner water proved toxic to one kind of fish.

Some antibiotics proved too toxic to be useful as drugs.

The presence of ammonia or nitrite can prove toxic to them.

Long-term exposure has proven toxic to a very wide range of animals including humans.

The combinations proved highly toxic at first, and many patients died or suffered lasting side effects.

The large amounts of ouabain used by the Indians proved toxic to their prey.

Each of the three researchers abandoned the first drug he or she developed because it proved too toxic for humans.