Karli-Rae
With the build up of PCB and mercury levels in fish, and documented lead poisoning in wildlife, I think that it's clear that the world isn't as big as we sometimes thought-- and that our unintentional actions can impact the environment--- so good on ya for asking the question.
There are non-toxic, lead-free alternatives to lead wire for weighting flies, widely available in many fly shops and from on-line shops selling fly tying material.
http://www.jsflyfishing.com/cgi-bin/...Free-Wire.html
It is a bit more expensive at about 2.60 for 5 yards as opposed to 1.75 or so for 5 yds of lead wire, and it is not quite as dense as lead, but it is safer for wildlife if ingested (though it is after all around a hook, so hopefully the hook doesn't cause injury). A standard guideline for using wire to weight hooks is that the diameter of the wire should be roughly similar to the thickness of the wire in the shank. Thicker wire for bigger hooks, thinner wire for smaller hooks. There still tends to be more options stocked by many fly shops in lead wire in terms of different thicknesses offered, but more and more shops are offering a wider choice of thicknesses in non-toxic wire.
There are also lead free alternatives to split shot etc. for weighting leaders/tippets.
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