Lead is obviously harmful and exposure should be reduced. Lead paint is still the greatest remaining concern as illustrated this week by a child in Washington DC whose blood lead was above 100 ug/dl because of lead paint in the home being rented under public housing authorities. Flint was a terrible situation that should never have happened. The only good news is that blood lead levels were only slightly elevated in about 2 % of the children to above 5 ug/dl--according to the 2016 CDC report. There was no increase above 10 ug/dl. For perspective, the 2nd NHANES national survey for 1976-1980 showed the AVERAGE child blood lead for the country was 16 ug/dl. Average child blood leads in the US are now about 1 ug/dl. The 5 ug/dl CDC number cited above is their 'reference' level that they estimate 97.5 % of children are below. I suspect they will soon change the reference level because more than 97.5 % are now probably below 5 ug/dl. Lead in children has dropped precipitously since the elimination of leaded gasoline, removal from food can solder, and elimination of lead based solder from water applications in 1986, and more lead service line removals. There are now about 50% fewer lead service lines since the 1991 Lead and Copper Rule was implemented, It is not always necessary to remove lead service lines to control lead leaching; proper corrosion control,such as phosphate addition at the water treatment plant works very well. So it is important to keep focus on the major problem which is old lead paint. Flint was an aberration. The problem in Flint was that the Lead and Copper Rule was not being enforced by the State of Michigan, which was their legal responsibility. Standard practice was not being followed when they changed water sources that increased the corrosivity of the water. The water taste, odor and color were so obviously bad that few people drank it. That is why there were not very high blood lead levels.
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
Lead is obviously harmful and exposure should be reduced. Lead paint is still the greatest remaining concern as illustrated this week by a child in Washington DC whose blood lead was above 100 ug/dl because of lead paint in the home being rented under public housing authorities. Flint was a terrible situation that should never have happened. The only good news is that blood lead levels were only slightly elevated in about 2 % of the children to above 5 ug/dl--according to the 2016 CDC report. There was no increase above 10 ug/dl. For perspective, the 2nd NHANES national survey for 1976-1980 showed the AVERAGE child blood lead for the country was 16 ug/dl. Average child blood leads in the US are now about 1 ug/dl. The 5 ug/dl CDC number cited above is their 'reference' level that they estimate 97.5 % of children are below. I suspect they will soon change the reference level because more than 97.5 % are now probably below 5 ug/dl. Lead in children has dropped precipitously since the elimination of leaded gasoline, removal from food can solder, and elimination of lead based solder from water applications in 1986, and more lead service line removals. There are now about 50% fewer lead service lines since the 1991 Lead and Copper Rule was implemented, It is not always necessary to remove lead service lines to control lead leaching; proper corrosion control,such as phosphate addition at the water treatment plant works very well.
So it is important to keep focus on the major problem which is old lead paint. Flint was an aberration. The problem in Flint was that the Lead and Copper Rule was not being enforced by the State of Michigan, which was their legal responsibility. Standard practice was not being followed when they changed water sources that increased the corrosivity of the water. The water taste, odor and color were so obviously bad that few people drank it. That is why there were not very high blood lead levels.
2 Comments
Ray-Right! I think blood lead half life is about 30 days. The good thing about the Flint child CDC data is that it represented thousands of samples in each period, before, during and after the water changes. By the way, I checked the Detroit data from 2013 (where Flint did and now gets its water). The Detroit blood leads were higher than Flint's in 2013 and also during the Flint problem. Detroit had about 8% above 5 ug/dl whereas Flint's were around 3% in 2013. I think a lot of both are coming from old housing with old lead paint. Pennsylvania also reported a lot of cities with elevated blood leads which they attribute mostly to lead paint. The other source in water that nobody mentions is adsorption and release from old galvanized iron pipe, again old housing that has not been rehabed.
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
Good information Joseph, thanks. The blood lead levels used to indicate harm potential status and trends in public health can be very misleading, since they primarily only indicate current lead exposures or uptake only during the last several months. Blood lead levels quickly reduce by the body sequestering the lead in bones and teeth in accumulative fashion. This sequestration does help the current toxicologic risk of other physiologic pathway degradation, but tends to only put off the risks until stresses later in life (old age, illness, or pregnancy) develop to cause the body to seek to mobilize the calcium stores in bone to fill the sudden need for added calcium to build defensive molecules needed to counter the stresses. At such times, calcium is low in supply, and since the body does not correctly identify lead as being other than calcium, lead comes out with the Ca and becomes incorporated into the defensive components being made from calcium and zinc. This contamination of stored lead makes many of the molecules such as zinc finger proteins dysfunctional. The body thinks that it has responded well to the stress but has not because the accumulated body lead has poisoned the bodies defenses. Blood lead levels can thus drop well, because either the exposures have lessened, or because the body has been effective in storing it in bone, or both mechanisms. Any time the bbl drops, helps the current pathogenicity of the lead to the immediate physiology, but usually only postpones the damage till later in life when stresses remobilize it at precisely the vulnerable times of old age, illness, or pregnancy. Once body burden has increased, we all have increased risks through life from that lead uptake that has occurred earlier. The public health paradigm commonly misrepresents the meaning of the blood lead testing results, erroneously giving the impression that the dangers from the lead exposures have all passed, but science is not served well by this incomplete picture provided by the authorities. Bone lead levels are now 100 to 1000 times those that prehistoric bones had accumulated. Our bodies have not had evolutionary time elapsed to adapt better defense mechanisms to the greatly increased environmental pollution once we dug the lead up out of the ground and dispersed it around the globe as products that easily degrade to be taken up to contribute to our health challenges. As you say, prevention is primary, because once in the body, much of it stays there to eventually do more damage.
Published by Ray Kinney