铅从哪里来Lead Poisoning

What is it and who is affected?
    Lead is a highly toxic substance, exposure to which can produce a wide range of adverse health effects. Both adults and children can suffer from the effects of lead poisoning, but childhood lead poisoning is much more frequent. Over the many years since we have known about the hazards of lead, tens of millions of children have suffered its health effects. Even today, in 2004, there are still at minimum more than four hundred thousand children under the age of six who have too much lead in their blood.

Where is it found?
    There are many ways in which humans are exposed to lead: through deteriorating paint, household dust, bare soil, air, drinking water, food, ceramics, home remedies, hair dyes and other cosmetics. Much of this lead is of microscopic size, invisible to the naked eye. More often than not, children with elevated blood lead levels are exposed to lead in their own home.
By far the biggest source of concern is the lead paint that is found in much of our nation's older housing. Until 1978, lead paint was commonly used on the interiors and exteriors of our homes. Today, the US Department of Housing and Urban Development (HUD) estimates that about 38 million homes in the US still contain some lead paint. While lead paint that is in intact condition does not pose an immediate concern, lead paint that is allowed to deteriorate creates a lead-based paint hazard. It can contaminate household dust as well as bare soil around the house, where children may play. In either situation, a child who comes into contact with lead-contaminated dust or soil is easily poisoned. All it takes is hand-to-mouth activity, which is perfectly normal for young children to engage in. All it takes is the lead dust equivalent of a single grain of salt for a child to register an elevated blood lead level.
According to HUD, about 25% of the nation's housing stock—some 24 million homes—contains significant lead-based paint hazards, i.e. deteriorating lead paint or lead-contaminated dust. These are the homes producing the vast majority of the childhood lead poisoning cases we see today.
    Children and adults too can get seriously lead poisoned when renovation and remodeling activities take place in a home that contains lead paint. Anytime a surface containing lead paint is worked on, the debris and the dust created by the work must be contained and thoroughly cleaned up, and those doing the work must have adequate personal protection to prevent them from breathing in any lead dust generated by the work. It is therefore of critical importance that lead painted surfaces be identified prior to the commencement of any renovation or remodeling work, and that lead-safe work practices are used during such activities. Of course, steps must also be taken to ensure that children, pets, and personal belongings including furniture are protected from exposure to lead while work is ongoing, as well.
    The past use of leaded gasoline, only recently banned in this country, contributed greatly to the number of cases of childhood lead poisoning in the US during the last sixty years or so. The lead produced by vehicle emissions continues even today to present a hazard, as much of that lead now remains in soil where it was deposited over the years, especially near well-traveled roads and highways. Children who play in dirt contaminated by lead (whether that lead is from gasoline emissions or from deteriorated house paint) can end up with lead-contaminated soil under their fingernails or on their toys, or they can track it into their homes. Even pets can come into contact with lead-contaminated soil and cause human exposure to lead. In each such case, an elevated blood lead level can easily result.
    Drinking water can also sometimes contribute to elevated blood lead levels. Lead can leach into drinking water from certain types of plumbing materials (lead pipes, copper pipes with lead solder, and brass faucets). While water is usually not the primary source of exposure to lead for children with elevated blood lead levels, it is nevertheless important to note that formula-fed infants are at special risk of lead poisoning, if their formula is made with lead-contaminated water.