By Roy Benaroch, MD
Lead is a natural element, found in abundance on the earth– at least once it’s extracted from ores. Under normal circumstances, humans probably shouldn’t be exposed to any lead at all, which is a good thing, because lead is a potent toxin.
It’s also a very useful chemical; civilizations going back to the Greeks figured out how to extract it and use it in paints and plumbing. More recently, lead has been used extensively not only in paint and cosmetics, but also in gasoline and many industrial applications.
Attention to the toxic effects of lead increased in the twentieth century. Lead has been banned in paints in the United States since 1978 and was phased out of most gasoline starting in the 1980s. Our children are exposed to far less environmental lead now than 20 years ago: in 1988, about 9% of children had elevated lead levels, compared to 1.4% in the most recent large survey from 2004.
Even though exposures are decreasing, recent research has shown that lower levels of lead exposure may be dangerous than previously thought. This month, a CDC advisory panel recommended lowering the threshold for concern of lead poisoning from 10 mcg/dL to 5 mcg/dL.
Lead can cause symptoms both from acute exposure to high levels and also from chronic, low-level exposures. Children with acute lead intoxication can have irritability or sluggishness, plus GI symptoms like vomiting or constipation. More common, though, are prolonged, lower-level exposures that may not have any obvious symptoms at first. In the long run, children (including not-yet-born babies) exposed to even relatively low levels of lead can have behavior and learning problems.
The effects of lead poisoning depend on many things other than the lead level. Different people have different susceptibility to the effects of lead (that’s probably genetically determined.) Certain other health conditions, like iron deficiency, seem to have an additive effect on lead poisoning. Effects also depend on how long the level was elevated—the longer a child is exposed to lead in the environment, the worse it can be. Earlier exposures seem to cause more problems than exposures in later childhood.
The best treatment for lead exposure is the prevention of exposure by limiting the lead in our environment. Lead paint has been banned but might still be found in layers of older paint in homes. During renovation, old layers of paint can be chipped off or turned into dust that can contaminate a home. Lead paint also occasionally is found in toys produced overseas, and lead contamination has been found in herbal and other medical products. Some hobbies (like stained glass and ceramics) and occupations involve exposure to lead in solder and glazes. Targeted screening following established guidelines for children at risk for lead exposure can help identify children in need of closer monitoring and treatment.
Further steps can help reduce your children’s risk of lead exposure:
- During renovations (including sanding and painting) of homes older than 1980, make sure that contractors follow established safety protocols for testing and containment of lead-containing dust.
- Beware of chewing or teething toys that are painted.
- Stay away from unregulated herbal and “natural” products, especially those produced overseas.
- Encourage government regulation and financial support for programs that monitor lead exposures and study ways to identify and treat people at risk.