Lead may be absorbed through the skin, lungs, or intestinal tract. Inhalation is the most common source of occupational lead poisoning. When lead is inhaled, up to 50% of the lead particles can reach the lungs, depending upon the size of the particles. Larger particles will be trapped by the mucous membranes of the upper respiratory tract and be expelled while smaller particles can reach the deeper areas of the lungs where they can then be absorbed into the bloodstream. A person who inhales small particles of lead dust, mist, or fumes has a higher risk of lead poisoning than a person who ingests lead paint chips. Exposure may also occur when using contaminated hands to handle food, chew tobacco, or smoke cigarettes. Lead quickly binds to red blood cells and diffuses into soft tissues such as the bone marrow, kidneys, liver, and brain.
While some of this heavy metal will be filtered out and excreted, the rest will remain in the bloodstream and soft tissues. Eventually, lead diffuses into bone where it can be stored for several decades. Continued exposure to lead increases the amount stored in the body and will slowly cause irreversible damage if not found and treated. Contributing factors that determine the level of risk include the degree of lead exposure, the amount of lead one was exposed to, and the duration of the contact, as well as age, gender, diet, genetic makeup, lifestyle, and current health status.
Some activities that can expose workers to lead include grinding or machining metal that contains lead, melting pure lead, handling scrap metal, and welding steel pipes painted with lead-based paints. Exposure can also occur when working in a smelter or foundry, manufacturing or recycling lead-acid batteries, cleaning indoor firing ranges, or working on lead-encased cables. Lead fumes are created when radiators, electronics, or stained glass are soldered and dust containing lead is produced during removal of lead-based paint. Metal working fluids can contain lead when lead-based metals or alloys dissolve during manufacturing processes.
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