The end of the lead weight era

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

2airishuman

Contributor
Messages
2,659
Reaction score
1,958
Location
Greater Minnesota
# of dives
100 - 199
Why do we still use lead dive weights? How much longer will they be common?

Lead is toxic and poses various environmental, handling, and disposal problems. Since the 1970s, there has been a gradual effort worldwide to reduce worker exposures to lead, and to reduce the amount of lead released into the environment:
  • Lead birdshot was outlawed for hunting of migratory waterfowl in the 1970s, with restrictions gradually affecting other types of hunting also.
  • The Restriction of Hazardous Substances Directive, adopted in 2003, caused a worldwide move to lead-free solder in electronic products.
  • Increasing regulatory burden and enforcement in specific market areas, e.g. children's toys, paint
Lead has three useful properties for diving:
1) It is dense, at 11 grams/cc, so that weights need not be large.
2) It has good compatibility with salt water.
3) It is relatively inexpensive.

There are other alternatives. Iron, at 8 grams/cc, is heavy enough, and cheaper than lead, and is useful if encapsulated (by plating or coating) or alloyed to prevent corrosion. Bismuth is non-corrosive, and widely used as a lead replacement, but is expensive ($15/pound) and production is not sustainable. Many other metals in widespread industrial use are workable alone or in combination and reasonably priced -- copper, tin, etc. Of all these, iron in the form of stainless steel, is perhaps the most plausible replacement.
 
yep, dense and cheap, just like me. Also, it's maleable/soft so it does less damage when dropped on a fiberglass boat deck.
 
I never have liked the shot weights, they leak the lead that flakes off when moved around. I dare say anyone that has experience with them has seen it happen. I would have banned them long ago.

I don't have a problem with solid weights. I've pulled a number off the bottom that have been there for a decade or more from the condition and type of belt and they looked to be the same condition as the one I use, and the weight is consistent with its markings. Once the patina is on the lead it is inert until damaged.

Not saying that a change would not help the environment, and it may very well happen over time, but getting rid of the shot belts would solve the vast majority of the problem quickly.

And if people don't drop belts now because of the cost, imagine if we used some real dense material, like say gold.


Bob
 
The surface area of the soft shot weights is huge. I think they should be banned.

I only have plastic coated lead weights. They cost just a little bit more than uncoated lead weights.
 
This as interesting thread; thanks for starting it. A couple thoughts, though I'm not a chemist so take it with a grain of salt.

1. Lead paint has specific hazards you won't find in lead weights. You get lead compunds that are more easily absorbed into blood.
2. I think with lead shot in lakes is an issue because of the quantity added. It's not really very soluble, but eventually you get enough lead in the sediments it becomes an issue. It'll end up reacting with something and form the nasty compounds like you might see in paint....
3. Solder is interesting. Not sure itsi a concern for workers or just the sheer quantity of electronics going to landfills.

I suspect lead will be around for awhile in diving. That said, the less surface area exposed the better. My old 11.5 pound waist weights have low surface area relative to the mass. New shot weights have high surface area. Coating could limit the surface area.
 
A couple thoughts, though I'm not a chemist
I am.

Lead is toxic and poses various environmental, handling, and disposal problems.
Lead is toxic, but it all depends on how it's served. Solid metallic lead isn't particularly toxic (unless it passes through a vital part of your body at high velocity), it's when it's soluble it's harmful. Lead bound in organic substances like TEL is toxic. Dissolved lead ions are toxic. But metallic lead is extremely passive; back in the days they lined sulfuric acid production towers with lead since it was able to withstand the corrosive action of concentrated sulfuric acid. It's all about the chemistry. Chlorine is extremely toxic, but we ingest large amounts of chlorine as its salt (NaCl, common table salt) every day with very few ill effects.

Lead birdshot was outlawed for hunting of migratory waterfowl in the 1970s, with restrictions gradually affecting other types of hunting also.
Lead shot is extremely durable, since it's quickly covered with a dense layer of oxides. Unless it's ground down in the bird's gizzard, it's basically harmless. The scientific reason for banning lead shot for waterfowl hunting is that the waterfowl don't have an ample supply of gravel for their gizzard, so they'll pick and swallow any gravel-like thing they find. So the shot is lodged in their gizzard and is slowly ground to small, more-easily-dissolved particles. And the hunter(shots fired)/area ratio is noticeably larger in waterfowl hunting areas, so the lead shot load on the environment is rather noticeable.

Bottom line: unless there are special circumstances, lead weights and lead shot are mostly harmless.
 
Swimming pools often ban shot weight because loose shot from a burst bag can clog the filters, not because of an environmental concern. They may also ban uncoated hard weights, because they are more likely to chip paint and tiles than vinyl-coated hard weights.

I volunteer in a major aquarium; we use shot and hard weights, even though concern for the fishes is major in all operational and equipment considerations.

I think hard weights in the ocean are a non-problem, and probably shot weights too.
 
I never have liked the shot weights, they leak the lead that flakes off when moved around. I dare say anyone that has experience with them has seen it happen.

I don't know how wide the affects are, so I'll leave that to the chemists, etc. BUT, I will say that after rinsing and drying our shot bags, when I lift them off of whatever drying surface I used, a majority of the time there is a white residue left in the shape of the weight. I've assumed that it was/is lead. We are slowly migrating to more solid weights but realistically, we'll probably have the soft weights for a while. At time of purchase I thought that the soft weights would be more comfortable. In practice I've never had one of our hard weights be any discomfort. If I were to start from scratch again, they'd be solid weights.
 
https://www.shearwater.com/products/perdix-ai/

Back
Top Bottom