The lowering of the reference dose for perchlorate is significant and could result in drinking water regulatory levels far below existing action levels in many states. As stated in the EPA Perchlorate Frequently Asked Questions:

"The assessment provides a hypothetical conversion of the draft RfD to a drinking water equivalent level (DWEL), assuming factors of 70 kilogram (kg) body weight and 2 liter (L) of water consumption per day.  The converted draft estimate would be 1 microgram per liter (ug/L) or 1 part per billion (ppb) (emphasis added).  If the Agency were to make a determination to regulate perchlorate, the RfD along with other considerations would factor into the final value."

Also today, the California Department of Health Services took immediate action upon release of the EPA document and has posted on their web site a reduction in the Action Level for perchlorate from 18 ppb to 4 ppb.

Utilities that could be impacted by a lower regulatory level for perchlorate include the users of the Colorado River as well as users of groundwater with this contaminant present.

Perchlorate should not be confused with chlorate.  Chlorate is a compound that is produced as a breakdown product of sodium hypochlorite and as an inorganic disinfection byproduct from the use of chlorine dioxide.  We issued a news alert regarding the posting of the chlorate action level on the California DHS website yesterday, January 17, 2002.