Q1 2026 heavy-metal screen — six suppliers, two failures

Mushrooms are bioaccumulators. The mycelial network is great at extracting trace minerals from substrate — including ones we don't want concentrated. The four heavy metals on every reputable mushroom-extract COA are:

• Lead (Pb) — neurotoxic, no safe exposure level for chronic intake.
• Cadmium (Cd) — kidney and bone toxicity at chronic exposure; particularly bioaccumulated by mushrooms.
• Mercury (Hg) — neurotoxic, bioaccumulates in lipids.
• Arsenic (As) — both inorganic (toxic) and organic (less so) forms; total arsenic on the COA is conservative.

The USP <2232> specs for dietary supplements (which most mushroom extracts default to) are:

• Pb ≤ 0.5 µg/g (typical), 1.0 µg/g (max)
• Cd ≤ 0.3 µg/g
• Hg ≤ 0.15 µg/g (inorganic), 0.5 µg/g (total)
• As ≤ 1.5 µg/g (inorganic), 5.0 µg/g (total)

We run our suppliers' material against the tighter "typical" column, not the max. If a sample fails the typical spec but passes the max, we ask for source-substrate provenance and decide whether to keep them on.

Six suppliers, fruit-body extracts only. All shipped product within the last 60 days. Independent third-party lab (ISO 17025 accredited).

Four passed cleanly with all four metals well under the typical specs.

Supplier 3 (turkey tail extract) — cadmium 0.42 µg/g. Above the 0.3 µg/g typical but below the 0.5 µg/g max. Asked for substrate provenance: they had switched a section of their operation to a new substrate vendor in late 2025. We've put their product on hold pending a re-test on a batch that's confirmed back to the original substrate source.

Supplier 5 (chaga wild-harvest) — cadmium 0.51 µg/g, arsenic 2.1 µg/g (total). Both above the typical, cadmium just above the max. Wild-harvested chaga is well-known for variability — birch trees pull soil metals into their wood, the conk concentrates further. We've removed them from the supply chain entirely until they can demonstrate consistent compliance over multiple lots, which for wild-harvest is a hard ask.

0.4 µg/g of cadmium sounds vanishingly small. Worth doing the dose math.

A typical chaga supplement dose is 1-2 grams per day. At 0.5 µg/g cadmium that's 0.5-1.0 µg/day cadmium intake from the supplement. The EPA reference oral dose for cadmium is 1.0 µg/kg/day for water and 5.0 µg/kg/day for food — so for a 70 kg adult, the supplement alone would be 1-2% of the food RfD. Not catastrophic in isolation.

But: most consumers taking a chaga supplement are also eating food. And cadmium has a 10-30 year biological half-life. Chronic exposure compounds. The job of the supply chain isn't to stay below an acute toxicity threshold; it's to keep cumulative exposure as low as reasonably achievable, especially for a daily supplement someone might take for years.

This is why we screen quarterly, why we use the tighter "typical" spec, and why two failures out of six this quarter is the reason we screen at all. Two suppliers caught means two lots of consumer product never shipped under the OMGX label. That's the entire point of the program.