A range of synthetic and natural substances have been identified that also possess estrogenic activity.

The Mayor has said he wants to end government's role in providing the drug, a synthetic substance used to curb the craving for heroin.

The raw materials for many of these synthetic substances come from crude oil.

The term is also used for synthetic substances of similar properties.

It is a synthetic substance based on plants such as the chrysanthemum.

Fortunately, the can had been made of some kind of synthetic substance.

He said a "synthetic substance, similar to a lubricant," had been found on the tracks and was being analyzed.

These were entirely novel synthetic substances and no species (including man) had acquired any previous experience of them.

"They're not really quartz, but a synthetic substance the Alfings can make," he explained.

And it would allow the agriculture secretary to approve synthetic substances if no organic substitute was commercially available.