I think I've identified (through various web research, mostly reading various gun and cast bullet boards, some product research) likely sources of my lead exposure. I'll be working on these, and am getting retested in several months. The consensus among guys who've had lead in their blood before (what their docs said) was that you need to get treated if you're over 40 mcg/dL but below that, try to eliminate your exposure to lead and let your body clear it out over time.
Lead exposure sources to consider:
1) your skin - if your skin hasn't been thoroughly cleaned in the area where they take the blood sample (like the inside of your elbow), you may get a false high reading due to lead in the dead layer of skin being introduced into the needle when it goes into you. Clean the sample area extra thoroughly prior to getting your blood draw.
2) dust from your case tumbler- Case tumblers are supposed to be chock full of lead from the primers, and unfortunately a lot of it is in a very fine dust that can easily be inhaled. I've started doing the dryer sheet thing where I cut up a dryer fabric softener sheet and put the pieces in every time I tumble cases now. It does come out filthy with dust and dirt on it so I think this is removing a lot of dust that might have gotten knocked into the air.
I now make a real effort to not breathe when i have it opened up, and am getting a respirator.
3) Hygiene- wash hands thoroughly every time handling reloading components. I have been wearing latex gloves while doing this, but haven't been paying enough attention to the washing, and laundering clothes immediately after doing lead activities.
4) it is not likely that simply melting lead will release lead fumes into the air, but why take a chance? I'm doing my casting outside now and/or wearing a respirator.
3M Model 6000http://store.pksafety.net/asledu.html
Home Depot and Lowes around me seem to just have the pesticide ones, so for the same $30 or so I ordered one specifically intended to filter lead. I may later buy the $20 cartridge that also has activated charcoal in it to filter even more stuff out, I'll see how my retest goes.
I suspect that breathing gunsmoke in is where some of my exposure is, but I don't see wearing this to the range unless I'm there by myself.