BLUE TONGUE SKINKS

Hello everyone, Australian here. I've recently discovered that organic topsoil that's free from additives is strangely difficult for me to find. I did manage to find a local gardening supply company selling bags of "screened topsoil" so I sent them an email concerning its "organic" status, specifically pertaining to the use of pesticides and the like. The response I received essentially stated that the use of chemicals was very unlikely due to where they source the soil (e.g. excavating basements), but they couldn't confirm with any certainty. Am I overthinking this? Should I consider this soil, for all intents and purposes, "safe" (post sifting and baking), or is it too great of a risk and better to look elsewhere? Thank you for your time and apologies for my potentially silly questions .