By David Chang, Ph.D., P.E., Chair, SDWA Committee, CA-NV AWWA, Golden State Water Company
It is certainly a busy time on the California
state front since the last issue. During the
• The California Department of Public
Health (CDPH) lowered the Notification
Level (NL) for 1,4-Dioxane to 1 part per
• The Office of Environmental Health
and Hazards Assessment (OEHHA)
proposed revised Public Health Goals
(PHG) for perchlorate at 1 ppb;
• The OEHHA re-proposed chromium
(VI) PHG at 0.02 ppb; and
• The Federal Department of Health and
Human Services proposed a change
in optimal fluoridation dosage from a
range to a set quantity.
Recently, CDPH lowered the Detection
Limit for Reporting Purpose (DLR) for
1,4-Dioxane from 3 ppb to 1 ppb. Since
the NL for 1,4-Dioxane is based on the
DLR, CDPH also lowered the NL to 1 ppb.
Because the new NL, CDPH has requested
some utilities to collect samples from wells
that are considered vulnerable and have not
being monitored for 1,4-Dioxane for several
years. If 1,4-Dioxane is detected (above 1
ppb), water utilities are required to notify
governing bodies within 60 days. Water
utilities also need to report this data in their
Consumer Confidence Reports.
The OEHHA proposed a revised Public
Health Goal (PHG) for perchlorate in
drinking water. The original perchlorate
PHG was established in 2004. However,
new data on environmental exposures and
possible effects of perchlorate, in addition to
further consideration of infants as a susceptible
20 SOURCE spring 2011
population, have resulted in the present
proposal to decrease the perchlorate PHG
from 6 ppb to 1 ppb.
As we all know, the PHG is the level of
drinking water contaminant at which adverse
health effects are not expected to occur from
a lifetime of exposure. The California Safe
Drinking Water Act of 1996 requires OEHHA
to develop PHGs based exclusively on public
health considerations. PHGs published by
OEHHA are considered by the California
Department of Public Health (CDPH) in
setting drinking water standards (Maximum
Contaminant Levels, or MCLs).
The new MCL may hinge on what CDPH
considers to be the reasonable DLR.
Currently, the DLR for perchlorate is at 4 ppb.
Some laboratories have developed capabilities
to report levels as low as 1 ppb. The new
MCL could be between 1 to 4 ppb. The main
concern of water utilities in Southern California
is whether the new MCL will be at a
level that is lower than the perchlorate levels
existing in the Colorado River Water. If the
Colorado River Water requires treatment for
perchlorate, the cost will be astronomical.
Currently, only two states—California and
Massachusetts—adopted MCLs for perchlorate.
The perchlorate MCL for Massachusetts
is 2 ppb. Several other states, including
Arizona, Maryland, Nevada, New Mexico,
New York, and Texas have established nonenforceable,
advisory levels for perchlorate.
USEPA is considering whether to set a
Federal MCL for perchlorate
In the last issue, I mentioned that, at the
request of stakeholders, the OEHHA
commissioned a peer review of the proposed
PHG for hexavalent chromium. According to
OEHHA, the peer review concluded that the
proposed PHG is based on good science and
is now re-proposing the 0.02 ppb PHG.
However, one of the five reviewers raised
concerns about the proposed PHG. Dr.
Toby Rossman, of the New York University
Langone School of Medicine, expressed his
concerns that a “threshold” for hexavalent
chromium is not considered even though
evidence and research indicates that a
threshold exists. He also said that the using
of LED10 is overly conservative and coupled
with a lack of threshold, an uncertainty
factor of 3000 and an upper 95-percentile
estimate of water intake, the results indicating
0.02 ppb for PHG is “unrealistically”
The main concern of water utilities in Southern
California is whether the new MCL will be
at a level that is lower than the perchlorate
levels existing in the Colorado River Water.