Did some kind of toxic substance get into his system?

"It is the single most toxic substance known to man."

White blood cells also help to fight other toxic substances.

The latter two are on the government's "red list" of particularly toxic substances.

The product could be a flame or a toxic substance.

Otherwise, the storage site for this toxic substance will be the human body itself.

It's one of the most toxic substances known to man.

This could cause exposure to lead paint or other toxic substances.

He said there were no indications that toxic substances had been found.

About as much concern was also shown for workers exposed to toxic substances.