Yes—if you plan to eat what you grow, your urban planter boxes should be made from materials that will not contaminate the soil or the plants. “Food-safe” is not a perfect or strictly regulated label for planter boxes, so the practical goal is to avoid materials that can leach harmful substances into your growing medium.
Start with the container material. Untreated wood such as cedar, redwood, or plain pine is generally a good choice, but avoid old pressure-treated wood, especially CCA-treated lumber, which can contain arsenic. Modern pressure-treated wood is less risky than older treated lumber, but many edible gardeners still avoid it, particularly where roots or soil touch the wood. Also avoid creosote-treated wood, old railroad ties, and reclaimed wood with unknown paint or treatment. If you use wood that is not clearly food-safe, line the inside with a food-grade HDPE plastic liner or another inert barrier, and make sure drainage still works.
Plastics can be suitable if they are stable and intended for food contact. HDPE and food-grade polypropylene are common safer choices. Avoid recycled tires, unknown recycled plastics, and PVC products that may contain problematic additives. If a plastic container smells strongly of chemicals or was previously used for motor oil, pesticides, or unknown materials, do not use it for edibles.
Metals need some thought. Food-grade stainless steel is a strong option. Galvanized metal may release zinc, especially in acidic soil, so use a food-grade liner if you are unsure. Avoid containers with chipped lead paint or decorative glazes that may contain lead. Concrete can be used, but it may raise soil pH over time; a liner can help. Ceramic pots should be labeled food-safe or glaze-safe for edible plants.
The soil matters just as much as the box. Use a clean, quality potting mix designed for vegetables and herbs. In urban areas, test your soil for lead and other heavy metals if you are using ground soil or recycled soil. If contamination is possible, use raised beds with a barrier, fresh soil, and good drainage. Wash homegrown produce before eating it, and keep planter boxes away from busy roads, peeling building paint, and industrial dust where possible.
Finally, avoid non-food-safe paints, stains, and sealants on surfaces that contact soil or plants. If you want to finish the outside of a wooden box, use a food-safe sealant or leave it untreated and accept natural weathering. Good drainage, clean containers, and safe materials will do more for food safety than a fancy label. In short: choose known, stable materials, avoid toxic treatments and unknown recycled containers, use clean soil, and test when in doubt. Your edible garden does not need to be complicated, but it should be material-smart.