Tests of drinking water in Chicago homes by federal inspectors this spring found high levels of lead in a number of them, officials said.Health advocates and scientists say lead could be an underestimated health risk in the nation\'s drinking water, especially in older cities and suburbs where lead pipe and solder are common in water supply systems, the Chicago Tribune reported Friday.The Environmental Protection Agency reported high lead levels in seven of 38 Chicago homes tested.\"That\'s not really good news,\" said Marc Edwards, an environmental engineering professor at Virginia Tech who researches lead in water.The allowable amount of lead -- 15 parts per billion -- was set in the 1990s.Experts argue there is no safe level of exposure to lead. \"What you really want is zero,\" said Jeffrey Griffiths, a professor of public health and medicine at Tufts University School of Medicine who is chairman of a drinking water advisory board for the EPA.\"Four (parts per billion) is better than 15, but four is still four.\"