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Worker Health Study Summaries

Research on long-term exposure

Lead Immunologic Findings (1) (Lead Exposure)


Study Background

In 1994, NIOSH conducted a study about how lead affects lead smelter workers.

We learned:

  • The parts of the body that fight infections did not appear to be harmed in smelter workers.
  • When standing on one foot, lead smelter workers’ balance was not quite as good as workers who didn’t work with lead.
Why did we do the study?

We did the study because other studies suggested that working with lead may:

  • make it harder for your body to fight infections or
  • cause problems with balance.
How did we do the study?

In 1994, we collected blood from two groups of workers. One group worked with lead at a lead smelter. The other group did not work with lead. We measured the blood lead levels in each worker.

We checked the way infection is fought by:

  • counting many types of cells that fight infections,
  • checking how well one of these types of cells worked, and
  • measuring antibodies in the blood (antibodies are proteins that fight infections).

We also tested how well workers in both groups were able to balance. We had workers stand still on a platform. The less the body moved the better one’s balance. We measured the following:

  • How far the body moved when a worker was standing on a hard platform with his eyes opened and closed.
  • Motion when a worker was standing on soft foam with the eyes opened and closed.
  • Motion when a worker was standing on one foot (left and right) on a hard platform with eyes open.

What did we find?

We looked at the results in lead smelters and in workers who did not work with lead. We found the following information about infections and balance.

Effects of lead on fighting infections
  • Both groups had about the same number of many types of infection fighting cells.
  • Both groups had the same amount of many antibodies.
  • Some cells in your body fight infections. Both groups were similar in how one of these types of cells worked.

A few tests showed minor differences between the smelter workers and the non-lead workers. However, we do not know if these minor differences affect the way the body fights infection. We also do not know if these differences are related to working with lead. Therefore, lead probably does not make it harder for the body to fight infections.

Effects of lead on balance
  • Members of both groups were similar in how well they balanced when standing on both feet.
  • When standing on one foot, the lead smelter workers moved slightly more than non-lead workers. This may show slight problems with balance in smelter workers. However, problems with balance did not increase with increasing blood lead levels in smelter workers. Thus, in smelter workers, it is not clear how blood lead levels are related to balance.
Remember what we found:
  • Working with lead did not appear to make it harder for the body to fight infections.
  • Lead smelter workers balanced less well than non-lead workers when they stood on one foot. However, under all other conditions, both groups had similar balance.

More information

For more information or if you want copies of these studies, call 800-356-4674 between 9 a.m. and 4 p.m. Monday thru Friday. If you call from a touch tone phone and a machine answers, immediately press 1 then 2 then 5. A person will answer.

If you call from a rotary phone, when asked to say “1” say “1”, Listen. When you are asked again to say “1” for publications, say “5” instead. A person will answer.

To receive documents or other information about occupational safety and health, contact NIOSH at:

NIOSH—Publications Dissemination
4676 Columbia Parkway Cincinnati, OH 45226-1998
Telephone: 800-356-4676
Fax: 513-533-8573
Web site:

Additional Resources

Dick R, Pinkerton L, Krieg E, et al. (1999). Evaluation of postural stability in workers exposed to lead at a secondary lead smelter. Neuro Toxicology 204(4):595-608.

Pinkerton L, Biagini R, Ward E, et al. (1998) Immunologic Findings Among Lead-Exposed Workers. American Journal of Industrial Medicine 33:400-408.

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