Module 3: Toxicology - Section 11: Lead
TOX 11.3: Lecture: Lead (Occupational Aspects)

WHY LEARN ABOUT LEAD?

Lead is important in occupational and environmental health for a number of reasons:

  1. Historically important.
  2. Environmental as well as occupational effects, particularly child health impact.
  3. A model for understanding multisystem toxicity – complex toxicology.
  4. Measurable --- one of the few substances with a long history of biological monitoring.
  5. Specific Lead Regulations in RSA.
  6. Understanding of how to run a lead medical surveillance and medical removal programme serves as model for managing other measurable toxic hazards.
  7. Chronic occupational disease due to lead can easily be missed and requires an understanding of chronic lead toxicology.

USES AND EXPOSURES

There are two forms of lead: inorganic and organic. They have quite different properties.

Inorganic lead use:

Mainly as lead oxide (PbO2) and lead fumes.

  1. Known exposures in SA:
    1. Mining: extraction, primary smelting, transport
    2. Secondary smelting (extracting lead from scrap)
    3. Battery manufacture (probably major occupational exposure in SA)
    4. Metal engineering (various)
    5. Wire drawing (tempering steel)
    6. Lining tanks with lead: “homogeneous lead burning” – extremely hazardous
    7. Radiator manufacture, repair
    8. Solder manufacture/use
    9. Lead pigments: dye, ink, paint manufacture and use (e.g. orange lead chromate, white plumbate primer)
  2. Possible exposures (historical, or current status not known):
    1. Motor vehicle assembly (lead wiping as finish)
    2. Panel-beating
    3. Foundries (fumes)
    4. Metallurgical assay (gold, etc.)
    5. Ceramics: glazing
    6. Glass manufacture
    7. Ammunition manufacture
    8. Radiation work (hospitals)
    9. Plumbing
    10. Plastics industry (facilitates extrusion moulding)
    11. Printing
    12. Jewellery manufacture
    13. Rubber industry
    14. Shipbuilding/repair
    15. Pesticide manufacture (lead arsenate)

Organic lead use

  1. Anti-knock agents in petrol: (tetraethyl and tetramethyl lead)
  2. Blending
  3. Filling?

Environmental/domestic exposure:

  1. Lead paint: deteriorating paint chips, in housedust, soil
  2. Exhaust fumes (inorganic lead fallout into soil)
  3. Use of lead lined vessels
  4. Battery burning as fuel
  5. Emissions from smelters?
  6. Water via pipes?
  7. Home "smelting" to extract lead (case of child poisoning in Soweto)
  8. Work-clothes of parent, spouse
  9. Sinker-making
Numbers occupationally exposed in SA?



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Postgraduate Diploma in Occupational Health (DOH) - Modules 3: Occupational Medicine & Toxicology (Basic) by Profs Mohamed Jeebhay and Rodney Ehrlich, Health Sciences UCT is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License. Major contributors: Mohamed Jeebhay, Rodney Ehrlich, Jonny Myers, Leslie London, Sophie Kisting, Rajen Naidoo, Saloshni Naidoo. Source available from here. For any updates to the material, or more permissions beyond the scope of this license, please email healthoer@uct.ac.za or visit www.healthedu.uct.ac.za. Last updated Jan 2007.
Disclaimer note: Some resources and descriptions may be out-dated. For suggested updates and feedback, please contact healthoer@uct.ac.za.