The Risk of Lead Poisoning From Scuba Diving Weights
As we all know, lead is a neurotoxin for humans. Every time you dive with shot lead weights, you may see a cloud of dust falling from the lead weights, even if they are 3-4 years old and used hundreds of times. Some scuba stores with pools on site usually have weights in the pool area, and lead weights are used in the pool on a daily basis. With all this contact with lead, are scuba divers at risk of lead poisoning?
Research into this issue has revealed relatively little information specific to diving weights. The only thing of real substance is on Dr. Ernie Campbell's outstanding Website, Scubadoc's Diving Medicine. Here's a synopsis.
They ascribe the risk of lead absorption from diving weights as minimal for divers; possible via the hands to mouth in divemasters, instructors and professionals who commonly handle weights. They suggest that divers rinse weights with fresh water after diving, wash hands after handling lead weights and even consider keeping weights separate from other gear.
While no studies have assessed the true risk, the rationale for the recommendations is that lead is changed chemically when it's placed in water. It can form various salts and chlorides that can be absorbed, and this process can be facilitated depending on the temperature and acidity of the water. The amount of surface area of the lead object is also a factor. As you describe, lead shot in bags offers significantly greater surface area than traditional lead weights, and pools are generally kept fairly warm. However, the chlorination process alkalinates the water, which is then filtered.
Furthermore, research has established clearly that inorganic lead can be absorbed through the skin, and accumulate in many organs while not being present in high levels in the blood. This may be problematic because blood testing is the primary means of assessing lead levels in people. The bottom line is that recreational divers probably have nothing to worry about; but dive professionals, especially those who routinely handle equipment, may be well-advised to wash their hands regularly.
One final note about children exposed to lead: Ingestion of lead dust is the greatest source of exposure to lead in kids, so this should be considered when dealing with the bagged lead weights. If this still doesn't set your mind at ease, research more about the occupational hazards of lead poisoning (plumbism), but as one writer has put it, probably the greatest hazard of lead diving weights is in handling them while wearing flip-flops.