For almost two centuries evidence has accumulated that lead damages virtually every organ system, including the central nervous system, cardiovascular system, red blood cells and kidneys. As each new set of data arrives, the lead industry intensifies its efforts to confuse the public and divert governmental controls. Recent events repeat the scenario, but with a corporate cynicism that reaches an appalling level. At the same time that new research is confirming the powerful influence childhood lead poisoning has on violent crime and learning ability, industry has argued that the US Environmental Protection Agency (EPA) should do away with standards limiting the amount that they dump in the air.
Lead's toxicity to those working in the industry has been known at least since 1839. (1) "As early as 1904, an Australian physician, J. Lockhart Gibson, published an article on the source of childhood lead poisoning among his patients." (2) Rick Rabin's history of the lead industry documents that it was well aware of the dangers by the 1920s. Criticism of the industry was a major factor in the 1928 formation of the Lead Industries Association (LIA) which worked to suppress information whenever it could.
The LIA was highly successful in campaigns to influence public opinion and halt or reverse legislation to regulate lead in paint. When the automobile became omnipresent after WWII, people were ill-prepared to resist leaded gasoline and became subjected to an even greater source of lead poisoning.
The year 1978 is often given as the time that US law banned lead from paint. That interpretation is deceptive. The use of lead in house paint began to decline long before. A zinc-based compound made its debut around 1920 as a substitute for white lead pigments. Latex paint came into use during the 1930s and was the main interior wall paint by the 1950s. (1) The 1978 ban on the use of lead in paint may have had less to do with a courageous Congress standing up to the paint industry than it did with the paint industry no longer needing lead. Legislation also phased out lead in gasoline, which fell by 70% from 1975 to 1984 and was ended by 1996. (3), (4)
Poisoning at low lead levels
Despite efforts by the industry to discredit research, medical information on lead has resulted in a continuous lowering of blood lead levels considered to be "safe." Before 1971, a child had to have 60 ug/dL (micrograms of lead per deciliter of blood) to be considered lead poisoned. That year it dropped to 40 ug/dL. The definition of lead-poisoned fell to 30 ug/dL and then to 25 ug/dL. The "level of concern" for lead adopted by the Centers for Disease Control in 1991 was 10 ug/dL. (5)
The CDC has refused to change that definition for almost 20 years, despite massive evidence that lead has more toxic effects and effects at lower levels than previously thought. Some of the most important work demonstrates how extremely low levels of lead damage intellectual development.
Investigations consistently show that (a) the greater a child's blood lead level is, the lower is the child's IQ; and (b) the largest incremental damage to IQ is in the 1-10 ug/dL range (which the CDC does not consider to be a "level of concern"). (6), (7) Typical is an investigation headed by Richard Canfield which found (a) an increase of blood lead from 1 to 10 ug/dL was associated with a decline of 7.4 IQ points; (b) an increase in blood lead from 10 to 30 ug/dL predicts an additional loss of 2.5 IQ points; and (c) the greatest damage to reading and math scores was for blood lead below 5 ug/dL. The authors concluded "that there may be no threshold for the adverse consequences of lead exposure and that lead-associated impairments may be both persistent and irreversible." (8) The sentiment that there is no "safe" level of lead is now echoed by experts throughout the field.
These studies are so powerful that it is easy to neglect recent findings on adults. For example, 2006 research reported in the Journal of the American Heart Association demonstrated that compared to those with extremely low levels, adults with blood lead levels of 3.6-10 ug/dL were 2.5 times more likely to die of a heart attack, 89% more likely to die of stroke, and 55% more likely to die of cardiovascular disease. (9)
Whither the CDC?
So what is the CDC doing with this accumulating evidence of the toxicity of lead at levels below 10 ug/dL? It is using doublespeak to make the problem worse. Health agencies across the US know full well that the phrase "level of concern" is a technical term referring to a specific concentration of lead but that most people interpret it as a dividing line between "lead-poisoned" and "not lead-poisoned."
Many agencies do not report the actual blood lead concentration in children and tell parents their child does not have enough lead for a "level of concern" if tests show lead below 10 ug/dL. Almost all parents hear such information to mean, "My child is not lead poisoned." Since no one tells them that intellectual damage can occur with low levels of lead...