Lead is being focused on in this thread, but there are many other heavy metals that are toxic and of concern in the environment. Quick quiz - What is the most toxic metal (takes the least amount by weight to kill a living organism).
Antimony? A favorite among unhappy wives to rid themselves of deadbeat husbands.
- A good try, but not quite
Lead? Common in environment, lots of household and industrial products use lead.
- Not even close
Arsenic? Used as an algecide and is the A in CCA presure treated wood.
-Nope, try again
Mercury? a nasty little critter that has a tendency to bioaccumulate or work its way up the food chain. Lots of recent concern over mercury contamination. Methyl mercury is now classified as a Supertoxin by EPA because of its ease of entry into the body through unbroken skin.
-Nice try
Plenty of other heavy metals, but I won't bore you with endless lists. I bet you cant wait for the real answer.
Silver. That's right Silver. It takes less of silver in an over all concentration in an organism to be toxic.
That's the same metal that many of us have a mouthfull of thanks to our dentists. The same metal that we use to make jewelry.
Before you run out and have all the fillings replaced in your mouth and hock all your wives jewelry listen to this. An important thing to remember when discussing metal contamination is the state that the metal is in and how bioavaliable that state is. If silver is so toxic why are we not affected by the silver in our mouths? Becasue silver is very difficult to dissolve where the silver is bioavailable. Silver is only soluable under very specific conditions. One of silvers great characteristics is that it is so stable and will remain where it is put (like your mouth) so long. Though silver is very toxic it is not available and therefore does not have toxic effects.
The same is true of lead. Metallic lead - ie the lead that you use as pencil lead is not very available. It needs to fe in a fairly concentrated acid to dissolve where it can become bioavailable. Stomachs of birds can be strong enough to dissolve some of this lead and introduce it to the food chain. Lead left as pencil lead on the stream bed will take years and years to dissolve and will probably be buried in the stream bottom where it will remain basically forever.
My goal in this post is not confuse the issue so as to justify my use of lead in fishing. I don't go through alot of it any more, except when I lose a downrigger ball Doh! I hope to simply inform and show others that the issue is not that straight forward.
Steve