It's always interesting when we discuss lead levels, I've tried to analise the different things that I do in relation to casting & shooting.
My Magna Caster is set -up in a 20' shipping container, I have both the end doors open and use a fan.
In earlier days I reckon I used to get a metallic taste in the mouth but since I stopped melting reclaimed shot I no longer get that taste,I'm thinking it's the arsenic that was in the shot..now I buy plain scrap lead & don't have a problem. I melt at approx 710 degrees, wear gloves & mask.
If I don't cast for a few monthe my levels do slightly drop,casting is not the main problem...IMHO it is definitely shooting & the type of range.
I regularly attend a range that is outdoors but confined by both overhead railing & side walls.....this I have proven to myself , when I shoot at this range with real BP my levels do go up, not as much when using smokeless [ strange..maybe not..think about it !! ]
My level has been as high as 20 & as low as 5 but vary regularly, unless you are excessively high or the lead gets into the bones in most cases there are no side affects. most shooters never get tested so would not know that their levels could be high.
I've learned to live with it , I'm not going to give up shooting & I have regular 3 month tests, always tumble outside, I never wear gloves when reloading using uncoated bullets as I find you lose the feel' & just to awkward., wash hands frequently especially before food.
Presently my level is 12.