The blood tests are used to look for the amount of certain substances in your blood.

The amount of such dangerous substances in the air could increase substantially during the next few months.

This checks the amount of substances in the urine.

The enthalpy changes also depend on the amount of substances involved in the process.

For example, could you reduce the amount of hazardous substances you buy and use every day?

Sea water contains about 3.5% salt on average, plus smaller amounts of other substances.

Such tests generally use a large amount of hazardous substances and energy.

Birds can land on its surface and take small amounts of radioactive substances with them.

It works by changing the amounts of certain natural substances in the brain.

The deal reflected the fact that a small of amount of banned substances and money were involved, she said.