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Lead is everywhere, due to its former widespread use in gasoline (until 1995 in the U.S.), and as a paint component (until 1978). Since it is not bio-degradable, it remains present in the environment, contaminating the soil, air, waters and food supply. Estimates are that the present levels of lead are greater up to 10,000, 200, 10 and 100 times in the air, soil, water and food, respectively, than before industrial contamination3 (the figures for air and soil are for inhabited areas).
Lead toxicity can cause anemia, brain damage, kidney disease, impaired growth and reproductive function, lower I.Q. or mental retardation in children (with millions of U.S. children having high enough level of lead to be affected), and so on. Even low levels of exposure are associated with hyperactivity, short attention span, learning problems and emotional disturbances.
In the last 38 years (since 1969), the official highest "safe" blood level of lead for adults has plummeted from 60μg/dl to 10μg/dl, with the gray zone 10-25μg/dl, and over 25μg/dl officially labeled as "associated with adverse health effects". Yet recent studies (Lustberg, 2002) have found that just having your lead blood level close to the latest upper "tolerable" limit (in the 20s vs. below 10μg/dl) increases your chances of developing cancer by 67%, suffering cardiovascular death by 33%, and dying from any cause by 46%12.
How tolerable it is, if it increases mortality by almost 50%?
This illustrates well how unreliable are the government and WHO (World Health Organization) safety standards when it comes to toxic substances. Most researches agree that there is no safe blood level of lead, especially for children. Since lead absorption rate for children is about five times greater than for adults, their official "safe" exposure level should be at least as much lower: 2 μg/dl "safe" and 5mg/dl "tolerable".
Obviously, since the "tolerable" limit for adults is not tolerable, we may look for still lower levels as truly safe or tolerable. And that doesn't even factor in that children also have
significantly slower rate of toxin elimination,
in general, due to their less efficient detox system. That brings us closer to understanding why it is good to assume no safe level of lead exposure, at least for children.
So, never mind the official "safe" levels. Considering that individual susceptibility can vary greatly, the lower your child's exposure to lead, the safer.
And keep in mind that the official "safe" level for any particular toxin assume that you are
exposed to that single toxin alone.
In reality, there is literally hundreds of other toxins present in your body. No one knows what are the actual safe levels with that many toxins affecting you at the same time, but they are certainly much lower. Most often, the combined effect of different toxins produces disproportionately greater harm to health, requiring significantly lower safe levels for each particular toxin in the mix.
Among foods with the highest levels of lead is chocolate. The source of contamination is still obscured. It is not in the cocoa beans themselves, but somewhere in the production process. The degree of contamination can vary significantly, and it is not carefully monitored. The highest measured lead concentrations in chocolate range from 0.23μg/g in the U.S. to over 8μg/g (2μg/g average) in India.
With the tolerable weekly lead intake for children set by the WHO at 25μg/kg of body weight, it is possible that the "tolerable" lead quota could be topped by a
regular consumption of chocolate alone.
But the official safe limit for lead, just as for most other toxic contaminants, is likely to be still too high. Many researchers believe that there is no safe intake level of lead, especially for children.
This is in line with a recent study conducted by the Cornell University (New England Journal of Medicine, 2003), which has found that as little as 1/4 of the level of lead considered safe by the WHO and the US Centers for Disease Control already causes growth retardation and lowered IQ in children.
No label will tell you what is the led concentration in a particular cocoa product. Consequently, the only reasonable solution is to minimize their use by children. More so considering that other sources of contamination are not negligible. With the estimated typical led content of air being 0.1-10μg/m3, the average amount of lead inhaled in a 24-hour period is up to ~140μg for a small child, and twice as much for an adult.
That alone would fill the "safe" lead quota for a
Factoring in lead from food, typically in the 0.01-10μg/g range, and 0.005-10μg/l for fresh water, shows that the danger of lead exposure having adverse effect on children is very real.
Other random sources of lead contamination can also be significant. For instance, corrosive acidic water - and acidic fluids in general - pull in minerals, including lead, from lead-containing containers, such as some crystals and pottery, and can significantly elevate its drinking water content (most municipal waters are acidic to very acidic).
Lead contamination originating from drinking water can be substantially reduced with proper filtration. When it comes to foods, you can only "filter" lead out by avoiding those with significant level of contamination. At present, such information is not available. For the sake of children, food lead content should be monitored and, when significant, presented on the label.