Hi Harmony,
Regarding the lead arsenate and whether you should be concerned, maybe.
According to wikipedia, "Lead arsenate was widely used in Australia, Canada, New Zealand, US, England, France, North Africa, and many other areas, principally against the codling moth. It was used mainly on apples, but also on other fruit trees, garden crops, turfgrasses, and against mosquitoes." It was discovered that it built-up in produce, so was eventually replaced with...DDT!
If you think there is a chance of lead and arsenic, have the soil from several areas tested.
Traditionally, if serious soil contamination was detected, you'd have to scrape off the top 6+" of soil, take it to the landfill, then replace it with 'new' soil. Fortunately, there is a better way if you are growing organically (or better, the permie way). You can 'lock up' the lead in the soil using phosphorus. You can read about it at
http://urban-homesteading.org/remediating-lead-in-the-soil. If arsenic is the problem, check at
https://soilsmatter.wordpress.com/2018/02/15/how-does-biochar-work-to-improve-or-even-decontaminate-soil .
I'm hoping this information is completely unnecessary for your farm. Good luck and good growing!
~Mary