Anyone know anything about lead in fruit?

A comment on the dried fruit post asks: ” in California, we now have warning labels on the shelves for balsamic and red wine vinegars for lead content…A lot of California grapes are grown close to highways, and as such, there’s residual lead in the soil from decades of leaded fuel. Do you have any sense about whether the lead is coming from the grapes being concentrated or if it’s coming from the barrels that they’re using to age the vinegar? …I wonder [if] white wine vinegars (or cider vinegar, or any other vinegar) aren’t equally implicated.

Anyone know anything about this? I’d like to learn more.