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7.B. -Page 11 of 15 City of Redwood City 2019 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. In 1995 the State of California adopted an Action Level of 15 ppb for lead, and requires the lead concentration in 90 percent of the water samples collected at customer taps not to exceed the Action Level. The California OEHHA revised the PHG for lead in drinking water from 2 ppb to 0.2 ppb on April 24, 2009, based on new studies relating to the most sensitive health risks. 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 the Action Level. The AL for lead has been set at 15 ppb because the 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. Health Risks Lead has multiple toxic effects on human body. The OEHHA revised the PHG for lead in drinking water based on new studies relating to the most sensitive health risks. These are non -carcinogenic, chronic health effects including neurobehavioral effects (decreased intelligence) in children and hypertension in adults. Lead also has the potential to cause kidney disease and cancer; however, the carcinogenic risks are considered smaller than the risks for chronic toxicity. The public health goal of 0.2 ppb was determined from a maximum daily lead intake through water ingestion of 2.86 Itg/day, which corresponds to a level of concern for neurobehavioral effects (in children) designated as a decrease of one Intelligence Quotient point. Best Available Technology for Lead Elimination DDW considers optimizing corrosion controls as the BAT to deal with lead in drinking water. In an evaluation report dated August 4, 2006, the SFPUC concluded that pH adjustment in the San Francisco Regional Water System, which supplies water to Redwood City, is the optimal corrosion control treatment. The report, which was then approved by the DDW, recommends a minimum pH of 8.2 (i.e. the optimal water quality parameter, or OWQP) be maintained throughout the transmission and distribution system. Because Redwood City continues to meet the Action Level for lead and operate the water system with pH greater than 8.2, DDW considers that the City has achieved optimized corrosion control. Therefore, additional corrosion control treatment is not needed. 5 324