Chemicals and Hazards

Chemicals that occur naturally or are created from industrial processes can have adverse health effects if you are exposed for a short time or over a long period of time.

Chemical List

Topics of Interest

What's ppm? ppt?

Chemical concentrations such as parts per million (ppm), parts per billion (ppb), or parts per trillion (ppt) are ways of expressing very dilute concentrations of substances. It usually describes the concentration of something in water or soil.

  • 1 part per million (ppm)
    = 1 in 1,000,000 or 1 x 10-6 or 0.000001
  • 1 part per billion (ppb)
    = 1/1,000 times 1 ppm or 1 X10-9 or 0.000000001
  • 1 part per trillion (ppt)
    = 1/1,000 times 1 ppb or 1 x 10-12 or 0.000000000001

How much is a part per billion or trillion?

One part per billion = 1 µg/L (microgram per liter)
This amount is equal to:

  • One drop of ink in a backyard swimming pool.
  • One grain of sand in a child's sandbox.
  • One second in 32 years.

One part per trillion = 1 ng/L (nanogram per liter)
This amount is equal to:

  • One drop of detergent in enough dishwater to fill a string of railroad tank cars 10 miles long.
  • One square inch in 250 square miles.
  • One second in 32,000 years.
Last Revised: March 13, 2018

Questions? Can't find what you're looking for? Contact us!