The soil at my former house (built around 1920) on a major street in a large college town, next to a bus stop, tested for significantly elevated lead and PCBs. I believe the soil on the other side of the building tested much closer to normal for the area.<p>I would test if there is even the slightest concern of contamination. Eating a few garden veggies here and there likely won't have much of an impact on an adult. If you're regularly supplementing your meals and/or feeding children, you may want to be more cautious.<p>At my current house on a busier, older street, I wouldn't consider eating anything grown in the soil. Most near me seem to use raised beds or the community garden.
If you do regular gardening you should just do a test anyway. University of Delaware has a kit I do every other year and gives plenty of data plus a plan (in my case for helping with my grass, but there are options for gardens).
If your garden is in the front yard of a house located close to a busy street in an old neighborhood, maybe so (not sure of the risk). But in the U.S., cars manufactured after 1975 used unleaded gas, and leaded gas was no longer sold after 1995. So I would think that in any subdivision built after 1975, the risk of lead in the soil caused by car emissions is very low. If any kind of industrial facility was previously on your land, you should test for more than lead.
Probably not, unless you think your property has some contamination. If it's really bothering you the tests are cheap, or possibly free through an extension.
This may put your mind at ease or at least help you determine how to mitigate any risk <a href="https://www.washington.edu/news/2016/02/02/risk-of-lead-poisoning-from-urban-gardening-is-low-new-study-finds/" rel="nofollow">https://www.washington.edu/news/2016/02/02/risk-of-lead-pois...</a>
Don't forget about lead paint. Any wooden house of age has likely been painted every 10 to 20 years, the paint chips scraped off during the preparation work can be a significant source of lead, especially close to the building.