Toxicants that are absorbed by plants during their growth from the hydroponics' nutrients, fertilizer, water, and soils and can trigger a range of health problems in low concentrations. Most cannabis regulations require producers to test for heavy metals and severely limit the amount available in the final form. Heavy metals commonly tested include arsenic, nickel, lead, mercury, copper, zinc, chromium, and cadmium.
Always test your soil for heavy metals to ensure they do not make it into your flower.
If your cannabis contains heavy metals, you could be inhaling dangerous things like lead.