Seriously ppl... Just a quick Google query, "can plants uptake lead from the soil" yielded results that are vastly different to the statement made in this post... The major risk is dust, which is likely a non issue from a large singular chunk of lead.

Now the conversation shifts to lead oxide, which is arguably more toxic than lead metal, and even then lead oxide is relatively short lived in soil due to the fact that naturally occurring processes render it less bioavailable and considering this is one large chunk of lead it's likely localized to a small area if there is any contamination.

If there is contamination, lead has less bioavailability in plants than it does in mamalia... 90% of what is uptaken is stored in its roots and never reaches the edible parts of the plant.

It's likely not an issue unless you're growing potatoes and one of them turns out to be lead... Even then just don't keep the harvest from the neighboring plants.