Katie - this is a very valid concern. I would reccomend that she get her soil tested. I believe you can take a dirt sample to the nc extension office.

The NC extension office can do the test for heavy metals in addition to the normal soil-testing they do. The heavy metal testing is an extra fee, from what I recall.

If you have an older house, be careful when you get a roof installed, as all the banging is apt to knock off paint chips into your foundation beds, too.

Also, looks like someone has leveraged the concern into a solution.

Indian Mustard is used to extract lead and arsenic from soil. I gotta think you need to ensure deer and such stay out of it. Else, you'll be making Bambi dumb.

There's an academic paper about the topic.