The constrictor did this by flicking its tongue over the man-made substances.

The distinction overlooks both the benign nature of some man-made substances and the deadly nature of some natural chemicals.

Synthetic surfaces contain, in addition to any natural materials, man-made substances such as metal alloys or polymers.

Carcinogens come from both natural and man-made substances.

Some valves are made of man-made substances.

And it did-the hardest man-made substance, and it couldn't stand up to the souls of human beings.

Plutonium, a man-made substance, is extremely expensive to produce.

Artificial oxygen carriers are man-made substances that can do the work of hemoglobin, the oxygen-carrying protein in your blood.

IN the war against chemicals that cause cancer, most of the attention has been on man-made substances like pesticides and preservatives.