21.   Mercury levels in the US environment have tripled over the last century, largely from the burning of coal and trash that contain traces of mercury.

22.   Nonalcoholic beer made its way onto store shelves recently, but officials considered banning it when they found it contained a trace of alcohol.

23.   None was found to contain traces of flammable liquids.

24.   Nothing in her home or mail or place of work at the Manhattan Eye, Ear and Throat Hospital contained any trace of anthrax spores, investigators say.

25.   One body exhumed in July contained traces of Pavulon.

26.   Pieces of a leg bone, considered more likely sites of bone marrow containing DNA traces, were ground to a powder.

27.   Remember the Martian meteorite that captured so much attention last year because it may have contained traces of cells?

28.   Rice straw contains traces of minerals such as silica.

29.   Supporters argue that hemp contains only traces of THC, not enough to provide a buzz.

30.   The crushed rock contains traces of gold, which will bond with liquid mercury dumped into the vat by villagers.