I think the toxic effects of lead has been pretty much been a closed book since ancient times and the long term effects of trace amounts in drinking water for a half a decade. It isn't some product of the "green police" of recent years that insist you can't have a mercury thermometer but insist you use the new mercury laden lightbulbs.
Arsenic is a natural element as well, doesn't mean it's good. Lead sinkers are probably fine to bury back in the ground from which it was mined, but not to be sitting in drinking waters. A few sinkers are harmless as well, however, if it's a heavily fished area there might be over 1,000 pieces of lead that's been sitting there for years. I know I lose 25 to 50 pieces a year, I'm sure some people lose much more.
Personally I use steel and lead, as some areas where I fish lead is outlawed. Eventually we'll likely see lead banned. Hopefully someone comes up with something better than steel and cheaper than Tungsten. Tungsten is most likely just as bad for the environment, but without 70 years of old tungsten sitting at the bottom of the lakes like lead, it will take a long time to build up enough to be an issue.