California Wants to Significantly Lower Level of Arsenic in Tap Water

The draft PHG proposes to identify 4 parts per trillion as a level of arsenic in drinking water that would not be expected to pose a human health risk. The current federal and state standard has been set at 50 parts per billion for many years. A new federal arsenic standard of 10 parts per billion will take effect in 2006. States may adopt a new standard that is equal to or more stringent than the federal standard. The U.S. EPA established a long-term Maximum Contaminant Level Goal (the federal counterpart to OEHHA's PHG) of no arsenic in drinking water.

In developing the draft PHG, OEHHA conducted an exhaustive analysis of all available scientific studies on the health effects of arsenic. The proposed PHG of 4 parts per trillion is based upon studies of hundreds of thousands of patients in Taiwan, Chile and Argentina with lung and bladder cancers associated with elevated levels of arsenic in drinking water. OEHHA estimates that a level of 4 parts per trillion of arsenic in drinking water would cause not more than one additional cancer case in a population of 1 million people drinking two liters of water daily for 70 years.

"Arsenic is a naturally occurring element, but it is also one of the most toxic substances commonly found in drinking water," OEHHA Director Dr. Joan E. Denton said. "Our public health goal, when adopted, will establish a long-term objective for the reduction of arsenic in California's drinking water."

Arsenic is found naturally in air, water, soil, mineral deposits and food. While arsenic in water typically is naturally occurring, the improper disposal of waste chemicals can also contaminate water supplies with arsenic. Long-term exposure to arsenic in drinking water can increase the risk of lung and bladder cancer and, to a lesser extent, increase the risk of skin, liver and kidney cancer. Other serious health effects stemming from long-term ingestion of arsenic in drinking water include heart attacks, stroke, diabetes mellitus, high blood pressure, liver and nerve damage, abnormal skin growths, and some reproductive and developmental problems.

State law requires OEHHA to develop PHGs for all regulated drinking water contaminants. A PHG is not a regulatory drinking water standard, and it is not a boundary between "safe" and "dangerous" levels of a chemical in drinking water. A PHG represents a health-protective level of a chemical in drinking water that can serve as a long-term goal for California's drinking water providers and regulators. Once the arsenic PHG is finalized, the Department of Health Services (DHS) will develop a new state drinking-water standard for arsenic that, by law, must be as close to the PHG as is economically and technically feasible.

The new national standard for arsenic in drinking water of 10 parts per billion was adopted in the last two years, but not without controversy. In May 2000, the Natural Resources Defense Council sued EPA to force it to issue a new arsenic rule to replace one that was established in 1942, before scientists knew arsenic caused cancer. EPA proposed a 5-parts-per-billion standard shortly thereafter. However, industry pressure forced the Clinton administration to settle on a 10-parts-per-billion standard, which it issued in January 2001.

In May 2001, the Bush administration announced that it was suspending the new arsenic standard. After a public outcry, EPA announced in October 2001 that it would keep the arsenic-in-tap-water standard it adopted at the end of the Clinton administration.

"California again is ahead of the federal government when it comes to protecting its citizens from preventable environmental hazards," said Dr. Gina Solomon, an NRDC physician. "We have the technology today to get arsenic out of our tap water, and there is no reason why Americans, wherever they live, should be exposed to high levels of arsenic."

A copy of the draft arsenic PHG document can be viewed or downloaded from OEHHA's Web site at www.oehha.ca.gov.

OEHHA will hold a public workshop to accept public comments on the draft document on May 2, 2003 at 10 a.m. in the first-floor auditorium at 1515 Clay Street, Oakland. OEHHA will also accept written comments on the draft document until May 2, 2003. Comments can be mailed to OEHHA's Pesticide and Environmental Toxicology Section, 1515 Clay Street, 16th floor, Oakland, CA 94612.

NRDC recommends a drinking water standard for arsenic of 3 parts per billion (ppb), which is the lowest level detectable with current technology. That standard, however, still presents a cancer risk 10 times higher than the level EPA considers acceptable in regulating other water contaminants. The California Office of Environmental Health Hazard Assessment is expected to announce a goal of 4 parts per trillion (ppt), the level at which arsenic poses no health threat.