Volume 19, Number 2 .... May 1997
The more I read about lead and lead poisoning, the more I am concerned about our exposure to lead. I don't mean to give short shrift to other heavy metal nasties: mercury, arsenic, and Def Leopard, to name but a few, but I think more of us come in contact with lead more often than we might care to acknowledge.
Professionally, we come into contact with lead in two different ways. The most obvious is from working with artifacts that are made from or repaired with metallic lead or lead compounds like lead white paint. Working with lead weights is the second.
This is, of course, added to the exposure that we are already getting from our living environments. Thanks to the gradual switch to unleaded gasoline in the late 1970's and its total banning on December 31,1995, the population as a whole is now exposed to far less lead than a generation ago. Unfortunately, lead water pipes continue to be a problem in many parts of the country. And then, of course there is flaking or chalking paint.
As conservators, we certainly know about this subject. And we certainly don't pick up flakes of paint and put them in our mouths. However, all things turn to dust. A chalking surface, a touch, and a few minutes later you eat your lunch. More surprising, a large amount of very fine, respirable dust can be generated by the rubbing of one painted surface on another. This fine dust can be found below painted sash windows, painted hinges on doors or below any area where two painted surfaces can rub against one another.
In a sense, children's exposure to lead is too important a topic for this column. Whatever bad things I say here, make it much, much worse and you will have a pretty good idea of the potential impact on a child. The picture is worse yet for a developing fetus. Life-long problems include lowered IQ ( 5.8 point decline per 10 µg/dl increase in blood lead levels ), increases in reading disabilities, and possibly an increase in antisocial behavior and delinquency.
Have we already been affected by the background lead all around us as we grew up? Very possibly. One lead researcher was quoted in Newsweek: "I guess we all might have been a little smarter than we turned out. It is hard to tell if someone goes from 140 IQ to 135."
Lead can be absorbed into the body via inhalation or ingestion. It is not readily absorbed through the skin, but skin contamination can easily be transferred to the mouth and ingested. Lead accumulates in the blood, soft tissues ( particularly the liver and kidneys on initial exposure ) and bones. The bones act as lead repositories, accumulating lead at the time of exposure and then slowly releasing it over time. Thus lead is a cumulative poison.
Quoting from the U.S. Department of Housing and Urban Development ( HUD ) publication Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing: "Adverse effects in adults include: Abdominal discomfort, anemia, colic, constipation, excessive tiredness, fine tremors, headache, high blood pressure, irritability or anxiety, loss of appetite, muscle and joint pain, pallor, pigmentation of the gums ( lead line ), sexual impotence, weakness, and the inability to keep the hand and arm fully extended ( wrist drop )."
Conservators represent a population with an odd mode of exposure. Those of us that are exposed are ( very fortunately ) only exposed infrequently. Typical examples are working on lead artifacts, particularly corroded lead, and removing old linings or patches from a painting that have been adhered with lead white paint.
We also use lead weights. Summarized in ACTS FACTS, an article in the AIHA Journal, "Potential Health Hazards from Lead Shielding" states that a significant amount of lead is shedded from lead used as radiation shielding. The same results would, no doubt, apply to our use of lead as weights in treatments and as counterweights in display cases. The study showed that both oxidized and freshly cleaned lead generate lead dust.
The article states a single coating of polyurethane on the lead reduced the amount of lead removal by three orders of magnitude. To this I would add my own observation: that polyurethaned lead ingots are dangerously slippery and should be painted with a textured paint to facilitate handling. A single coat of paint should be sufficient. Coating the weights first with polyurethane and then with paint would be even better.
Also from personal observation, lead shot is a very potent lead dust generator. I placed some lead shot into very small Ziploc style bags for use as weights. After a few days, to my great surprise, the inside of the plastic was black from the generation of lead oxide dust. For this reason, I believe lead shot must be very carefully sealed before being used as weights. Two layers of 6 mil polyethylene seems a minimum. If you are not sure how lead shot is encapsulated within a fabric or leather covered weight, investigate. ( Heck, you are a conservator, after all. ) Cloth weights that have no plastic liner should be replaced and the old cloth discarded.
So, let's cut to the chase.
Conservators have been very lax in protecting themselves against lead poisoning. There are two ways to attack this problem. We must either check all items to be treated for the presence of lead or the generation of lead based contamination. Or we can apply standard lead containment techniques to all projects that are potentially lead contamination hazards. I would argue that the second course is the safer and more productive.
Step 1: Buy a HEPA vacuum cleaner. The more I research this topic, the more I am convinced that it is morally imperative that only HEPA vacuum cleaners be used in an interior conservation setting. ( I promise that I will have purchased one before the next issue of the Newsletter. ) Conventional vacuum cleaners, brooms and dry mops are worse than inadequate because any lead contamination is blown all around the workplace. It is the finest dust which is most effectively scattered into the air, and that is the most dangerous to inhale.
When working on a project that is potentially a lead hazard, follow the rules developed for the safe remediation and abatement of lead based paint in domestic structures. For lack of space, I'll have to defer discussing this fully until the next column. If you can't wait that long, get ahold of a copy of the HUD publication listed below.
Also in the next column, I'll expound on:
As always, please contact me if you have had any experiences with lead poisoning or working safely with lead artifacts.
1 "As Leaded Gas Era Ends, New
Toxic Additive Appears," EDF Letter ( A Report to
Members of the Environmental Defense Fund ), Vol. XXVII, No. 2 (
March 1996 ), p. 8.
2Thomas H. Maugh II, "Study Says
Lead Exposure May Contribute to Crime," Los Angeles
Times, Wed. 7 Feb. 1996.
3 Steven Waldmand et al., "Lead
and your Kids," Newsweek, July 15, 1991, pp. 42-48.
4U.S. Department of Housing and
Urban Development ( HUD ), Guidelines for the Evaluation and
Control of Lead-Based Paint Hazards in Housing. June 1995.
772 pages. Available from HUD USER; P.O. Box 6091; Rockville, MD
20849; (800) 245-2691; The publication is available for a small
handling fee ( $8.00 when I ordered my copy ).
5"Metallic Lead Sheds Significant
Amounts of Dust", ACTS FACTS, ed. Monona Rossol,
Vol.11, No. 1, January 1997, p.4.
Chris Stavroudis is a conservator in private practice.
Timestamp: Thursday, 11-Dec-2008 13:02:35 PST
Retrieved: Tuesday, 23-Oct-2018 07:56:16 GMT