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7C Page 8 City oj Redwood City 2010 Public Health Goal Report Why Lead is Regulated In 1974, Congress passed the Safe Drinking Water Act. This law requires the EPA to determine safe levels of chemicals in drinking water which do, or may cause, health problems. These are non-enforceable levels based solely on possible health risks and exposure. The PHG for lead has been set at 2 parts per billion (ppb) because the EPA believes that this level of protection would not cause any of the potential health problems described below. Since lead contamination generally occurs from corrosion of household lead pipes, it cannot be directly detected or removed by Redwood City. Instead, EPA requires water systems to control the corrosiveness of their water if the level of lead at home taps exceeds an MCL. The MCL for lead has been set at 15 ppb because EPA believes, given present technology and resources, this is the lowest level to which water systems can reasonably be required to control the contaminant should it occur in drinking water at their customers home taps. These drinking water standards and the regulations for ensuring these standards are met are called National Primary Drinking Water Regulations. All public water supplies must abide by these regulations. The Health Effects of Lead Lead can cause a variety of adverse health effects when people are exposed to it at levels above the MCL for relatively short periods of time. These effects may include interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, slight deficits in the attention span, hearing, and learning abilities of children, and slight increases in the blood pressure of some adults. Long-term effects: From a lifetime of exposure at levels above the MCL, lead has the potential to cause stroke, kidney disease, and cancer. How Best Available Technology for Lead Elimination is Applied by Redwood City Optimizing corrosion control is considered to be the best treatment technique for minimizing household corrosion and reducing lead and copper levels at-the-tap at this time. Currently, the San Francisco Public Utilities Commission (SFPUC-the agency that provides all of Redwood City's drinking water) uses sodium hydroxide (NaOH) as the treatment technique for adjusting the pH of the tap water for optimized corrosion control. The City of Redwood City then monitors the pH levels of the water at the entry points and at sites strategically located throughout the Citys water distribution system to ensure that the proper pH is maintained. A report completed by the SFPUC reviewing its Corrosion Control Strategy for Lead and Copper Rule Compliance confirmed that pH adjustment remains the best strategy for optimizing corrosion control. The optimal treatment technique, approved by CDPH, is to raise the water to a minimum pH of 8.2; which the SFPUC and the City of Redwood City 4