Human beings need to drink for their survival. Water ranks【61】on the list of all-time safe fluids. But not all water is as safe as once【62】. Recent tests of water fountains in several U. S. cities show that many fountains give water containing large【63】of lead (铅) , a poisonous metal. A recent study of 900 water fountains in Los Angeles【64】that half of the fountains【65】contained higher amounts of lead than the【66】the experts consider【67】. In other cities【68】results of tests were announced too much lead in many, though【69】, drinking fountains. Water doesn't normally contain any lead, but when it passes through pipes, it can【70】. People who drink the water【71】the lead. An adult' s body passes most of the lead【72】the body, but children' s【73】retains more than half the lead【74】. This makes children more likely to be affected. Lead can damage the kidneys, cause【75】and impair learning and memory.【76】four million children in U. S. A. already have high levels of lead in their bodies. Most of this lead comes from【77】polluted with the metal. They can【78】it up from eating dirt or paint chips containing lead. In【79】to limit the lead in water fountains, officials recently suggested that fountains【80】to have too much lead be replaced or repaired. And that certainly requires a lot of money. (61)