How safe is safe?

I'm always skeptical of government standards when it comes to how much exposure to something is supposedly safe. Some drinks are allowed to have certain amounts of chemicals in them -- chemicals that have been linked to cancer, mind you -- just as long as they do not exceed the limits of what has been deemed "safe." The same goes for meat packaging plants; there are designated levels of "safe" rat excrement that are allowed. This time around, and with respect to the health of our hearts, it seems that the government's "safe" levels in lead exposure may not be all that (guess what?) safe after all.

Based on a report in the journal Circulation, researchers found that people who had levels of this metal from 3.6 to 10 micrograms per deciliter increased their risk of death from heart attack or stroke by 89 percent. Bear in mind, this 3.6 - 10 mcg/dL falls far below the 40mcg/dL threshold that the government has listed as being safe.

Lead is known to damage the kidneys, which, in turn, causes an increase in blood pressure and damage to the blood vessels. With that being the case, is any level of exposure truly safe? I know I have my doubts. What about you?