Heavy metals and CBD: EU limits and reading ICP-MS

Commission Regulation (EU) 2023/915 of 25 April 2023 covers maximum levels for certain contaminants in foodstuffs and repeals Regulation (EC) No 1881/2006. Its section 3 is headed "Metals and other elements" and covers lead (3.1), cadmium (3.2), mercury (3.3), arsenic (3.4) and then inorganic tin (3.5).

That text does not apply directly to a CBD flower or resin, which are not placed on the market as foodstuffs in France. The regulation confirms as much by omission: the only entries devoted to hemp are points 2.6.1 to 2.6.3, which set Δ⁹-THC equivalents for hemp seeds, processed seeds and hempseed oil. No line covers flower or resin, for THC any more than for metals.

A laboratory reporting a result on a resin therefore refers to the nearest category in the scale, food supplements, and that reference is an analytical convention, not a legal obligation. Our article on the 0.30% threshold describes the same mechanics on the cannabinoid side: the enforceable value comes from a French text, not from the contaminants regulation.

Three remarks on that table. First, the fifteenfold gap between cereals and food supplements for lead: a maximum level is not a toxicity threshold, it takes account of the quantities consumed. Then the spread within dried spices themselves, from 0.60 to 2.0 mg/kg depending on the plant part, which shows the scale follows the matrix as much as the element.

Lastly, arsenic. The maximum level for inorganic arsenic applies only to the products listed at points 3.4.1 to 3.4.4, essentially rice and its derivatives, infant formulae and fruit juices; total arsenic is capped only for salt, at point 3.4.5. No value exists for food supplements. A certificate announcing arsenic compliance "with the European regulation" on a resin therefore points at a line that does not exist.

The health-based reference values, for their part, come from EFSA and are expressed as a dose per kilogram of body weight: a tolerable weekly intake of 2.5 µg/kg for cadmium, with the kidney as the target organ chosen; a benchmark of 0.50 µg/kg per day for lead, tied to developmental neurotoxicity. Those benchmarks serve dietary risk assessment, not the judging of a batch.

Hemp takes up and accumulates the elements present in its substrate, which explains its documented use in soil remediation. A study published in Frontiers in Plant Science in 2023, run in hydroponic culture by Marabesi and co-authors, followed how cadmium distributed itself through the plant at four supply levels: 0, 2.5, 10 and 25 mg/L.

The useful result here comes down to two figures. The root concentrates by far the most: at the lowest supply level, its content is around one hundred and fifty times that of the leaves. But floral tissue accumulates it too, at 66.2 mg/kg in one experiment and 25.5 mg/kg in the other, for a supply of 10 mg/L. The authors conclude that the plant can accumulate cadmium in floral tissue.

Two limits have to be stated. The concentrations used exceed those met on agricultural soils, and the set-up is hydroponic, so far removed from a field crop. The study therefore allows no numerical extrapolation to a batch on sale. What it does establish is the pathway: the organ that is sold is not out of reach, which is why the check has to be run on the flower analysed and not on the soil alone. The CBD flowers catalogue states the growing method for each reference, useful context but no substitute for a measurement.

ICP-MS, inductively coupled plasma mass spectrometry, separates elements by mass-to-charge ratio after the sample has passed through an argon plasma. European standard EN 15763 describes precisely that use: determination of arsenic, cadmium, mercury and lead in foodstuffs by ICP-MS after pressure digestion. That last stage counts as much as the measurement: the plant material is brought into acid solution, hot and under pressure, before being injected.

For official controls, sampling arrangements and methods of analysis come under Regulation (EC) No 333/2007, which covers lead, cadmium, mercury, inorganic tin, 3-MCPD and benzo(a)pyrene. A serious certificate therefore names three things: the method, the standard followed and the laboratory.

The limit of quantification, or LOQ, is the smallest content the method can put a figure on with the required precision. It is not a property of the element but of the method-plus-matrix pair, and it changes from one laboratory to the next. Regulation 2023/915 draws the consequence itself at its section 2.6: levels refer to lower-bound concentrations, calculated on the assumption that any value below the limit of quantification is equal to zero. A result reported as "< LOQ" therefore means "below the figure this laboratory can quantify", never "absent".

Four checks are enough, in this order.

1. The batch. The number on the certificate must be the one on the pouch. A document with no batch documents nothing.
2. The method. ICP-MS for metals, with the standard cited. A certificate announcing metals without naming a method allows no comparison at all.
3. The limit of quantification. It must appear element by element, next to the result. Without it, a "not detected" cannot be verified.
4. The benchmark. The category the value is compared against must be named, with its section number. That is the only way to know whether the laboratory aligned itself with food supplements, with dried spices, or with nothing at all.

The same reasoning holds for the laboratory's scope of accreditation: accreditation to the ISO/IEC 17025 standard covers named tests, not the establishment as a block. A laboratory accredited for cannabinoids is not necessarily accredited for metals, a point our guide on scope of accreditation sets out in detail.

The our laboratory page describes a batch's journey: a sample sent to an independent laboratory accredited to the ISO/IEC 17025 standard, cannabinoids and terpenes quantified by high-performance liquid chromatography, the 0.30% Δ⁹-THC threshold checked before the listing goes live, a certificate published batch by batch. The method described covers cannabinoids and terpenes.

The contaminants block, where it exists, is read on the certificate itself, reachable from the batch's page: product pages carry the cannabinoid content and the terpene profile, not the metals. Reading a certificate line by line is set out in our guide on how to read a certificate of analysis; order questions are gathered in the FAQ.

• EUR-Lex, Regulation (EU) 2023/915 of 25 April 2023, consolidated version (accessed 16 September 2026)
• EUR-Lex, Regulation (EC) No 333/2007, sampling and methods of analysis for metals
• European Commission, sampling and analysis of contaminants
• EFSA, metals as contaminants in food
• EFSA, tolerable weekly intake for cadmium
• Marabesi et al., cadmium and transporters in Cannabis sativa L., Frontiers in Plant Science, 2023
• Cofrac, accreditation standards and reference documents