RESUMO
It is increasingly recognized that even very low lead exposure can result in measurable and permanent neurologic damage, especially to infants and young children. Although lead exposure from tap water continues to decline in the United States as a result of various regulatory and corrosion control measures, tap water continues to represent a significant (about 14 to 20 percent) source of total lead exposure. As of March 2002, nearly all valves used in residential plumbing systems continue to be made with 5 to 7 percent leaded brass. In this study, the authors measured the amount of lead discharged by these parts under laboratory conditions and found that the typical resident would be exposed to small amounts of lead, particularly from gate and ball valves. Typically, water passes through three to six such valves before reaching the tap. Thus, these leaded-brass valves represent a significant, widespread, and needless source of lead exposure to the U.S. public, especially given that numerous models of no-lead valves are now commercially available.
