A heavy metals panel quantifies the toxic trace elements most regulators require: lead (Pb), arsenic (As), cadmium (Cd) and mercury (Hg), sometimes with others such as chromium. The usual method digests the sample in acid and measures it by inductively coupled plasma mass spectrometry (ICP-MS), which detects elements at parts-per-billion levels.
In practice
Cannabis takes up metals readily from its root zone, which is why hemp has been studied for cleaning contaminated soils. That same trait makes metals a real risk in flower. Sources include contaminated soil, some fertilisers and amendments, poor water and equipment. A COA reports each element in µg/g (ppm) or µg/kg (ppb) against action limits that vary by jurisdiction and product type; check local rules. If a crop fails, test inputs, not just the flower.
µg/g = ppm; µg/kg = ppb. 0.5 µg/g lead = 500 µg/kg.
Don't confuse with
- Plant nutrients: iron, zinc, copper and manganese are essential micronutrients, not "heavy metals" in this regulatory sense, though they can be toxic in excess.
- Pesticide panel: organic chemical residues, a separate test.
A micronutrient is an essential element plants need only in trace amounts, below a few mg/L: iron, manganese, zinc, copper, boron, molybdenum, chlorine and nickel.The root zone is the volume of medium or solution where a plant's roots live, including its water, air, temperature, pH, EC and microbes.Hemp is cannabis grown for fibre, seed or other uses and, in many laws, defined as Cannabis sativa with no more than 0.3% THC by dry weight.A COA (certificate of analysis) is a lab's signed report of what it measured in a specific sample, such as cannabinoids, terpenes, moisture and contaminants, with methods and limits.Zinc (Zn) is a micronutrient needed for auxin production and many enzymes; deficiency gives small, twisted new leaves and shortened internodes.Copper (Cu) is a micronutrient used in photosynthetic electron transport and lignin formation; plants need only traces, and excess is toxic to roots.Manganese (Mn) is a micronutrient that splits water in photosynthesis and activates many enzymes; low pH can raise it to toxic levels.A pesticide panel screens a cannabis sample for a defined list of pesticide residues, typically by LC-MS/MS and GC-MS/MS, reporting each against its action limit.The LOD (limit of detection) is the lowest amount of a compound a method can reliably tell apart from zero, but not necessarily measure accurately.A batch (or lot) is a defined quantity of product from the same plants, harvest and processing run that is sampled and tested as one unit and carries one ID.
