The Centers for Disease Control and Prevention reported last December that levels of lead in children continue to decline. That's a scary thought to the lead-heads, who this week launched an effort to "head off" any further good news about lead.

To spotlight the upcoming publication of a new study by activist-researcher Dr. Bruce Lanphear, of the Cincinnati Children's Hospital Medical Center, The Alliance to End Childhood Lead Poisoning sponsored a press conference

Though the study will not be published/available for review by the public for weeks, Dr. Lanphear announced he had linked learning problems in children to extremely low levels of lead exposure, on the order of 5 micrograms of lead per deciliter of blood (µg/dl) and below.

Dr. Lanphear shrilled, "Lead is a major cause of many diseases of industrialization ... There is no safe level of exposure to lead ... Each of us has been adversely affected by lead and will be adversely affected until the day we die." Dr. Lanphear called for a total ban on the commercial use of lead.

But Lanphear's alarmism comes across as a lead balloon.

There is no question that "lead poisoning" can be harmful. But what is "lead poisoning"? Physicians and the lead-heads disagree.

Medical treatment for "lead poisoning" is recommended for blood lead levels above 45 µg/dl, according to the American Academy of Pediatrics. Environmental intervention — such as cleaning and repairing a home with deteriorating lead paint — is recommended for blood lead levels over 25 µg/dl.

But such high blood lead levels are rare and are becoming more so.

The CDC reported last December a 28 percent drop (from 10.5 percent to 7.6 percent) in the number of children with blood lead levels above 10 µg/dl. The CDC reported a 20 percent drop (from 1.5 percent to 1.2 percent) in the number of children with blood lead levels above 20 µg/dl.

Up until 10 years ago, such numbers would be cause for celebration at CDC. But in 1991, the lead-heads convinced CDC to reduce the level of concern for blood lead levels from 25 µg/dl to 10 µg/dl — that's where the lead controversy enters the junk science world.

Lead-heads claim low-level lead exposure is associated with lower IQ scores and behavior problems among children — a claim launched by a controversial 1979 New England Journal of Medicine study by University of Pittsburgh researcher Dr. Herbert Needleman.

Not everyone was impressed with Needleman's work, though. Critics uncovered many problems. Needleman didn't control for the confounding factor of child's age. Factoring in age yielded few significant results. Needleman also excluded from his analysis children who were "lead poisoned" without impaired intelligence. He also omitted other results that didn't support his conclusion.

Needleman was subsequently accused, but not convicted, of scientific misconduct. His work, however, was never vindicated.

As pointed out in the New England Journal of Medicine, "...the investigative bodies found Needleman's studies scientifically flawed ... involving a 'pattern of errors, omissions, contradictions and incomplete information...' The University of Pittsburgh... stated that had Needleman accurately described his methodology and subject selection, he 'would have risked rejection' of his article by the New England Journal of Medicine. In addition, the [federal] Office of Research Integrity cited misplotted graph points, which were found 'difficult to explain as honest error'..."

Subsequent studies, generally conducted by activist-researchers such as Lanphear, purport to support Needleman's original claims. But the studies suffer from the same basic flaw: Their weak statistical associations between blood lead levels and learning and behavior problems could easily be explained by socio-economic factors not adequately considered by the researchers.

After all, who's surprised that poor, inner-city kids underperform on cognitive tests?

Exposure to lead is not a problem for the vast majority of Americans and their children. More than $100 million is spent every year to monitor and reduce lead exposure among the populations most at risk for lead poisoning. The CDC data shows that progress is being made.

This progress is especially notable since commercial lead use has never been greater. Though lead is no longer used in U.S. gasoline and paints, lead has many other uses. Eighty percent of lead use is in automotive-type batteries. Leaded glass makes it possible to watch television and use computers safely.

Sadly, though, the lead-heads only see progress on lead exposure as a threat to their viability. They admitted as much during the press conference, stating that the purpose of Lanphear's study was to prevent the CDC report from being interpreted "incorrectly."

Ironically, the lower child blood lead levels go, the more shrill the lead-heads get. Lanphear noted that technology now enables the detection of lead in blood to the nanogram level — a billionth of a gram or 1,000 times lower than the microgram level.

The lead-heads apparently plan to be around for a while.

— Steven Milloy is a biostatistician, lawyer and adjunct scholar at the Cato Institute and publisher of Junkscience.com.