CHEMICALS IN THE NEWS

Arsenic

Arsenic is a naturally occurring substance that is sometimes found at very low levels in drinking water, primarily groundwater.

Studies from Taiwan suggest that exposure to drinking water containing more than 100 micrograms per Liter (mg/L) of arsenic – more than twice the amount allowed by U.S. law – may be linked to greater incidence of some forms of cancer. While there has been research indicating that low levels of arsenic in drinking water poses a risk to human health, scientists agreed that there are significant gaps in the data and that additional research is needed to formulate an appropriate level for a primary drinking water standard.

The EPA is required by the Safe Drinking Water Act Amendments of 1996 to finalize a new drinking water standard for arsenic based on good scientific information and data by January 2001. The current maximum contaminant level (MCL) is 50 mg/L. In May 2000, the EPA proposed an arsenic standard of 5 ug/L but is considering standards of 3 mg/L and 10 mg/L as well.

A recent memo from the Office of Congressional and Intergovernmental Relations to the EPA’s Arsenic Work Group published by the national Inside EPA newsletter raises further doubts about the rule. In it, EPA’s governmental affairs office warned that it "would not support a proposal of 5 ug/L, indeed, we have substantial concerns about a proposal of 10 ug/L as well."

In preparation for the proposed rule, EPA asked the National Academy of Sciences (NAS) to conduct a risk assessment for arsenic based on currently available science. The NAS report was released in late March 1999, and doesn’t recommend an arsenic standard. It does state that the arsenic regulation must be strengthened, but calls for more research to support an appropriate standard.

The EPA was supposed to publish a proposed rule to lower the Maximum Contaminant Level (MCL) of arsenic in January 2000. When they did not, the National Resources Defense Council (NRDC) sued the EPA. The NRDC also released a report on its estimate of the risks of arsenic in drinking water and contended that the MCL should be no greater than 3 mg/L.

In this report, the arsenic concentrations of many drinking water utilities were published, including those serving the Santa Clarita Valley. The NRDC took data from the EPA database and calculated different estimates of the average amount of arsenic in each water system. They calculated a "low" and "best" average based on the most current results. For the water systems in the Santa Clarita Valley, the results were between five and ten years old. The NRDC estimated that none of water served in the Santa Clarita Valley exceeded the current MCL of 50 mg/L, the expected proposed MCL of 5 mg/L, or the NRDC’s proposed MCL of 3 mg/L. Despite this, the NRDC’s estimates are still much higher than the actual levels in the drinking water of the Santa Clarita Valley. There have been no levels reported above 3 mg/L, and the majority of tests show no detectable arsenic at all.

For additional information on arsenic you can contact the EPA at www.epa.gov, the United States Geological Survey at water.usgs.gov or wwwsd.cr.usgs.gov, the California Department of Health Services at www.dhs.cahwnet.gov, the California Environmental Protection Agency (Cal/EPA) at www.calepa.ca.gov. Much of the information presented here was provided by the Association of California Water Agencies at www.acwa.com.

MTBE

Over the last several years, Methyl Tertiary Butyl Ether (MTBE) has been making headlines in California. Back in the 1980s, it was hailed as a major break-through in air pollution prevention. By adding it to gasoline, the amount of carbon monoxide released by automobiles could be greatly reduced. The California Air Resources Board (CARB) credits MTBE with removing three million pounds of carbon monoxide from our air per year. Both CARB and the EPA required that MTBE be added to gasoline.

In 1995 however, it was discovered that MTBE had contaminated the groundwater in the City of Santa Monica. It had leaked from underground fuel tanks and migrated into the City’s aquifer. Since then, many wells throughout California have been found to have similar contamination problems. MTBE has also been found in a number of lakes in California. In this case, the MTBE is not present because of leaking fuel tanks but rather from motorboats that burn gasoline containing MTBE. MTBE is foul tasting at even very low concentrations and there are many concerns about long term consumption of drinking water contaminated with MTBE. In response to these problems, California has banned the use of MTBE as a fuel additive. However, the EPA continues to require its use so it is still found in California’s gasoline. California has requested a waiver from the EPA, but it has yet to be granted.

All drinking water in the Santa Clarita Valley comes from the approximately 40 local wells and Castaic Lake. The Regional Water Quality Control Board requires that owners of underground storage tanks test the ground for contamination. A few leaking tanks have been found in the Santa Clarita Valley. However, the local wells have been tested every year since 1997 for MTBE at the CLWA’s Water Quality Laboratory. No MTBE has ever been found in any of the local drinking water wells.

The water in Castaic Lake has been tested by the Department of Water Resources (DWR) for possible MTBE contamination. MTBE and other gasoline components have been found on the surface of the lake, particularly near the boat launches. However, DWR has not found MTBE in the water leaving the lake. CLWA checks the water entering its two water treatment plants from Castaic Lake as well as the water leaving the plants at least 6 times per year. No MTBE has ever been found in Castaic Lake water delivered to the consumers of the Santa Clarita Valley.

For additional information on MTBE you can contact the EPA at www.epa.gov, the United States Geological Survey at ca.water.usgs.gov/mtbe or wwwsd.cr.usgs.gov, the California Department of Health Services at www.dhs.cahwnet.gov, the California Environmental Protection Agency (Cal/EPA) at www.calepa.ca.gov/programs/mtbe, the State Water Resources Control Board and the Los Angeles Regional Water Quality Control Board at www.swrcb.ca.gov.

Perchlorate

Perchlorate, a chemical used in making rocket and ammunitions propellants, has been a water quality concern in the SCV for the past few years. It was detected in 1997 in four Saugus Formation wells operated by purveyors near the former Whittaker-Bermite facility. These four wells have not been used as sources of supply since 1997. In November 2002, perchlorate was detected in an Alluvial well adjacent to the Whittaker site, and it was immediately closed. 

In 2002, CLWA and the U.S. Army Corps of Engineers signed a cost-sharing agreement for a feasibility study of the area. All proceedings and data are available to the public through a California Department of Toxic Substances Control (DTSC) information repository as well as public meetings. A notification level of 6 ug/L was determined in early 2004. DPH has adopted 6 ug/L as an MCL for perchlorate since that time.

The purveyors and the DTSC signed an oversight agreement in 2003 regarding studies of treatment technologies for removing perchlorate from water supplies, and have also been working with DPH to obtain the necessary permits for these treatment processes.  Treatment method pilot studies were conducted during 2003, and in 2004 CLWA and the purveyors selected ion exchange as the preferred treatment method for removing perchlorate. Design of the CLWA treatment facilities and related pipelines was complete in 2007. Construction of the treatment facility and pipelines began in November 2007 and water will begin being treated in early 2009.

Under federal and state law, the owners of the Whittaker-Bermite property have the responsibility for the groundwater cleanup. A final settlement to remediate and treat the contaminated water was completed and executed by the parties in April 2007.

NDMA

Another chemical making news lately is N-nitrosodimethylamine (NDMA). This chemical has been found on many of the same sites as perchlorate. Some NDMA has been found locally on the same Bermite site where perchlorate has been detected. However, in sharp contrast to perchlorate, NDMA has been found in very small quantities and has not been detected in any well water.

The EPA has classified NDMA as a probable carcinogen. However, EPA has not yet established a regulation or "Maximum Contaminant Level (MCL)" for NDMA. This is because NDMA is just now being detected and understood, and only a very small amount of information on NDMA exists - there is not enough information yet for EPA to set an appropriate MCL.

The California Department of Health Services (DHS) has established an interim "Action Level" level of 20 ng/L (nanograms per liter or parts per trillion). This is an extremely low level. In fact, if you were to fill the Rose Bowl in Pasadena all the way to the top row of seats with water, two drops of that water would be about the same as 20 ng/L. DHS put this very low level in place to provide public health protection while we wait for doctors and scientists to determine what a safe level of NDMA might be.

It may be possible that NDMA is formed as a by-product produced during disinfection of water or treating wastewater with chlorine. Such disinfection is critical to the safety of drinking water, as it kills the bacteria, viruses, and other microorganisms that cause such waterborne diseases as typhoid, polio, and dysentery—diseases that kill more than 10,000 children each day around the world.

At the present time, there are very few laboratories that can detect NDMA at these low levels, and there is no laboratory method that has been approved by EPA or DHS. CLWA and several other water agencies are working with DHS to try out new NDMA testing methods, and to determine if NDMA is present in local drinking water supplies.

In December 1999, the DHS laboratory detected 7 ng/L in the Rio Vista Treatment Plant effluent. However, at the same time Montgomery Laboratories in Pasadena did not detect any NDMA in the same sample. Montgomery Laboratories did detect 2 ng/L of NDMA in the effluent of the Earl Schmidt Filtration Plant. DHS did not analyze that sample. DHS and Montgomery Laboratories tested five more samples from various sites in the Santa Clarita Valley. No NDMA was detected in any of the other samples.

Additional information on NDMA can be found at the EPA and DHS web sites, www.epa.gov, and www.dhs.cahwnet.gov. Check our web site in the future for any new information we receive regarding the health studies on NDMA and the results of NDMA testing in your drinking water.

Chromium

Testing Results for Chromium

Neither Castaic Lake nor any of the Santa Clarita Valley’s wells have had any chromium detected in concentrations greater than 0.01 mg/L.

Chromium Fact Sheet (Courtesy of ACWA)

Chromium is an inorganic chemical that is used in electroplating, leather tanning, wood treatment, pigments manufacture and cooling tower treatment for corrosion control. Chromium can enter drinking water sources through discharges from industries, leaching from hazardous waste sites, and erosion of natural deposits.

There are two forms of chromium species that may be present in drinking water: chromium III and chromium VI. There are uncertainties in the balance of occurrence of the two species in drinking water sources. Chromium III is an essential nutrient at trace concentrations. Chromium VI is the primary species of health concern and its toxicity is the basis for setting the chromium drinking water standard. There is evidence that chromium VI may be reduced to chromium III in the human body, particularly in the reducing environment of saliva and gastric juices.

The EPA has classified chromium VI as a human carcinogen by inhalation. In 1991, EPA reviewed the existing chromium standard, and raised the Maximum Contaminant Level (MCL) from 0.05 mg/L (1975 Interim Drinking Water Standard) to 0.1 mg/L as total chromium, based on its decision that chromium VI was not carcinogenic by ingestion.

The California Department of Health Services (CDHS) reviewed the chromium risk assessment data in 1994, and maintained the State chromium MCL of 0.05 mg/L. In its 1999 risk assessment, the California EPA, Office of Environmental Health Hazard Assessment (OEHHA) disagreed with EPA's conclusion on the carcinogenicity of chromium VI. OEHHA determined that a health protective level against carcinogenicity for chromium VI was 0.2 ug/L(ppb), and set the Public Health Goal (PHG) for total chromium at 2.5 ug/L. The PHG was calculated assuming that total chromium in water is made up of no more than 7.1 percent chromium VI. (Note: More recent analyses suggest the proportion of hexavalent chromium to total chromium may be much higher.)

The California chromium MCL is currently under review. CDHS has indicated that it must have more occurrence data before considering revising the total chromium MCL, or adopting an MCL for chromium VI. CDHS plans to add chromium VI to the list of unregulated chemicals for which monitoring is required when the Department amends the existing unregulated chemical monitoring regulation to be effective in 2001.

Because chromium VI is not a regulated contaminant, there are no officially approved analytical methods for compliance purposes. The EPA Method 7199 (and other equivalent methods) uses Ion Chromatography followed by post-column derivatization. The Method Detection Limits are typically between 0.2 to 0.3 ug/L. One commercial laboratory in southern California has so far been identified as capable of measuring chromium VI at concentrations below 0.2 ug/L.

More information on chromium can be obtained from OEHHA and DHS.