The plants grew well in growing media that contained toxic levels of mercury.

Those with slow metabolism could take a lower dose to prevent toxic levels of a drug from building up in their body.

Do you realize all it takes to reach toxic levels?

Mercury can build up to toxic levels in the human body and cause neurological damage.

This means they're more likely to build up toxic levels of some common drugs.

But if we put a lot more in, then there'd be the possibility that people could reach toxic levels of it.

When the enzyme is not working, those other drugs can build to toxic levels.

Medical advice suggests that they are not yet at toxic levels, which would pose a threat to human health.

The amount of fluorine added to the water supply is not at the toxic level.

Pollution in major cities throughout the world has reached such toxic levels that hundreds of people die from it every year.