Cpt Dale writes:

Overall, while its always a good idea to eliminate pollution sources,
the contribution of this one is masked by background noise, namely the
lead that already occurs in seawater.

It is estimated that the Earth contains around 326 million cubic miles
of water, of which roughly 300 is seawater, as per:
http://www.celestopea.com/OTEC.htm

A detailed composition of seawater can be found here:
http://www.seafriends.org.nz/oceano/seawater.htm

...which states that Lead is present at around 0.00003 ppm.

What this means is that (300 million) * 0.00003 (parts/million) = 9,000
cubic miles of lead are currently in the oceans.

To convert this to a mass, lead is around 8.5g/cc, so the amount of
lead already in the oceans is:

= [(8.5 gram)/ (1 cm^3)] * (9000)
(miles^3)*(5280ft/mi)^3*(12inch/ft)^3*(2.54cm/inch)^3*(1lb/454gram)*(1
ton/2000lbs)

= (8.5)*(9000)*(147,197,952,000)*(1728)*(16.387064)*(1/454)*(1/2000)

= 351,173,909,301,987 tons

= ~350 trillion tons

Assuming that every diver in the world were to lose a quarter pound per
year, at 2 million active divers, that's a half million lbs/year, or
250 tons/year.

This sounds like a lot until you divide to get the Signal:Noise ratio:
it then works out to roughly a "1 to quadrillion" ratio.

What this would work out to is that for a 1 part per billion change, it
would require 1 million years of diving (eg, 1B * 1M = 1Q).

Pragmatically, if we look for the significant manmade sources of lead
pollution of our oceans, we find that most are due to lead being an
airborne combustion byproduct that then comes out due to rainfall.  I
believe that the big contributors are considered to be from vehicle
emissions (in particular from back when we used tetraethyl lead in
gasoline, at around a 1%-2% concentration).  Coal for electrical
generation is also a known contributor, but the EPA estimated that they
released only 3,283 tons of lead compounds into the environment in
1999, which was <2% of all lead released by industries (which summed to
188,686 tons of lead and lead compounds into the environment in 1999),
and worldwide, the total sum would obviously be higher.

Using this last datapoint and our previously listed assumptions,
divers' weightbelts would notionally be responsible for no more than
~0.1% of all lead pollution.

-hh

Yep, and if it tracks into the house or you don't clean your hands
before eating (remember to wipe off the faucet handles afterwards too),
you can expose yourself or your family and your pets to lead poisoning.
Lead gets stored in your brain, organs, and bones after leaving your
bloodstream - so even getting a blood level won't tell you your lifetime
exposure to the stuff.

If you do notice lead dust from soft weights, don't try to vacuum it -
you will just throw it into the air where you can breathe it into your
lungs.  Sweeping dry can do the same.  You should mop it up with a wet
rag and bag it for disposal. Be especially careful if kids are in the
house.

I can't swear that all led shot is coated, only that some of it is.  I'm
quite sure that some of my weights specifically mentioned that the shot was
coated.

Correct.  That's why articles discussing the issue have always said that,
when you notice grey water coming from your shot pouches, it's time to
replace them.

It's time to replace them.

Lee

At least some of mine said they were.  I can't be sure about all of them.
They were bought over quite a few years, some before the risk was common
knowledge.

Lee