Elemental Impurities in Ayurvedic Herbs: What USP <232>/<233> Testing Reveals About Your Supply Chain

Twenty percent. That’s the share of Ayurvedic herbal products tested in a widely cited 2008 JAMA study (Saper et al.) that contained detectable levels of lead, mercury, or arsenic — often at concentrations far exceeding what USP <232> considers acceptable for daily oral ingestion. And that was before FDA tightened import scrutiny on this category.

If your brand sources Ashwagandha, Shilajit, Triphala, Brahmi, or any other Ayurvedic botanical raw material, you’re operating in one of the highest-risk ingredient categories for elemental impurities. Most supplier Certificates of Analysis won’t tell you that. A full ICP-MS screening panel run by a qualified analytical testing laboratory will.

Here’s what the testing data actually shows — and what it means for your regulatory exposure.

Why Ayurvedic Raw Materials Carry a Disproportionate Heavy Metals Risk

The contamination story in Ayurvedic herbs runs deeper than soil quality — though soil quality is a real part of it.

Soils in parts of South Asia — including regions of India, Nepal, and Sri Lanka that supply the majority of commercially traded Ayurvedic botanicals — have naturally elevated levels of arsenic, cadmium, and lead. Crops absorb what’s in the ground. It’s not always fraud; it’s often geography. But it creates a compliance problem for supplement brands importing those materials that doesn’t disappear because the ingredient is “natural.”

Then there’s Rasa Shastra. This branch of traditional Ayurvedic medicine deliberately incorporates processed metals and minerals — mercury (parada), lead, arsenic, and iron — into therapeutic formulations. Practitioners hold that specific purification rituals called shodhana render these metals therapeutically safe. US regulatory agencies don’t accept that argument. FDA has issued import alerts (including Import Alert 66-41) targeting Ayurvedic products that contain heavy metals at concentrations posing a health hazard, regardless of how the metals were traditionally processed.

Shilajit deserves its own paragraph. This resinous mineral pitch — harvested from Himalayan rock formations and increasingly popular as an adaptogen ingredient — is inherently mineral-dense. Authentic Shilajit contains dozens of trace elements, some desirable (fulvic acid–bound iron, zinc, copper, manganese) and some decidedly not (arsenic, cadmium, lead). Importantly, fulvic acid complexation doesn’t neutralize heavy metals; it simply changes their matrix presentation, which can complicate certain analytical methods.

The practical result: our team regularly receives Shilajit lots with supplier CoAs screening only 4 elements — the “big four” of lead, cadmium, arsenic, and mercury. When we run full USP <232> panels via ICP-MS, we sometimes find additional elements — chromium, nickel, thallium — that the supplier simply wasn’t looking for.

What USP <232> and <233> Actually Require — and Where Supplier CoAs Fall Short

USP <232> (Elemental Impurities — Limits) and USP <233> (Elemental Impurities — Procedures) have been integrated into DSHEA-compliant quality programs since FDA incorporated USP standards into its cGMP guidance under 21 CFR Part 111. If you’re manufacturing dietary supplements in the US, these chapters aren’t optional reading.

USP <232> establishes Permitted Daily Exposures (PDEs) for 24 elemental impurities across three administration routes. For oral products — which covers virtually every powdered herbal raw material — the key limits are:

• Lead (Pb): 5 µg/day
• Cadmium (Cd): 2 µg/day
• Inorganic Arsenic (As): 15 µg/day
• Mercury (Hg): 3 µg/day (inorganic)

Those numbers sound like comfortable thresholds until you calculate them against actual serving sizes. A product with a 3 g daily dose of Triphala powder needs that ingredient to contain no more than 1.67 µg/g (ppm) of lead to stay within the 5 µg/day PDE. Depending on the source region and harvest conditions, that’s not always a comfortable margin.

USP <233> describes what the analytical testing laboratory must do to validate the measurement procedure. That includes spike recovery requirements (typically 70–150%), calibration linearity verification, limit-of-quantitation confirmation, and matrix-matched standards. This validation piece matters enormously because herbal matrices are analytically complex. High polyphenol content, sulfur-containing phytochemicals, and organic acids can all interfere with elemental detection if the method isn’t properly characterized for botanical substrates.

Here’s the practical compliance gap: a typical supplier CoA from a South Asian ingredient manufacturer shows results from an in-house lab screening 4–6 elements, often using ICP-OES rather than ICP-MS, without documented method validation against USP <233>. That document doesn’t constitute USP <232>/<233> compliance for your quality program. Under 21 CFR Part 111.75, the responsibility to confirm identity, purity, strength, and composition of incoming raw materials sits with you — the manufacturer. That responsibility doesn’t transfer because a supplier handed you a piece of paper.

What a Full ICP-MS Panel Actually Finds

The honest answer is that results vary significantly by lot and source region. But the failure rate in Ayurvedic ingredient categories is higher than most brands anticipate when they first start testing independently.

Lead exceedances are the most common finding. Arsenic comes second, though the interpretation gets complicated by speciation. Standard ICP-MS measures total arsenic. Total arsenic in soil-origin and marine-origin botanicals often includes substantial fractions of organic arsenocompounds — arsenobetaine, arsenosugars — that are orders of magnitude less toxic than inorganic arsenic species. USP <232>‘s 15 µg/day PDE applies specifically to inorganic arsenic. So a material reading 30 µg/g total arsenic by ICP-MS might actually pass once you run IC-ICP-MS speciation and confirm that 85% is organic arsenobetaine.

Or it might not. That speciation step is what separates a pass from a fail — and it’s the step most supplier CoAs skip entirely.

Cadmium tends to distribute more evenly across source regions but spikes in crops grown in heavily industrialized agricultural zones with phosphate fertilizer use. Mercury is less common in raw botanicals but emerges regularly in Rasa Shastra-derived extracts and in some Shilajit products where mercury-bearing minerals are present in the source rock formation.

One pattern we see consistently: lots from the same supplier brand can vary substantially from batch to batch. A material that tested clean six months ago may not test clean today. Seasonal variation, changes in sub-supplier sourcing, different farm plots, and shifts in processing can all affect elemental profiles. Testing one lot doesn’t validate the next one.

The Proposition 65 Complication Midwest Brands Often Overlook

Brands headquartered in Illinois or elsewhere in the Midwest sometimes assume California Proposition 65 is a California brand problem. If you’re selling nationally — including through Amazon, which ships to California customers regardless of where your fulfillment center sits — that assumption needs revisiting.

California’s Prop 65 Maximum Allowable Dose Levels (MADLs) are materially stricter than USP <232> PDEs for several key elements:

• Lead: MADL of 0.5 µg/day vs. USP PDE of 5 µg/day — a 10x difference
• Inorganic Arsenic: No Significant Risk Level (NSRL) of 10 µg/day vs. USP PDE of 15 µg/day
• Cadmium: MADL of 4.1 µg/day (USP’s 2 µg/day PDE is actually stricter here)

A product that clears USP <232> limits on lead can still require a Prop 65 warning label. That label triggers questions from retail buyers, creates friction on Amazon storefronts, and invites scrutiny from private-attorney enforcement actions under Prop 65’s citizen suit provisions. A single Prop 65 enforcement settlement — even a modest one — typically costs far more than a year of pre-market ICP-MS screening would have.

The math isn’t complicated. A 1,000 mg Ashwagandha capsule at a two-capsule daily serving delivers 2 g of raw material per day. If your Ashwagandha lot contains 0.6 µg/g lead, you’re delivering approximately 1.2 µg lead daily — within USP’s 5 µg/day PDE, but more than double California’s 0.5 µg/day MADL. Products sold in California need a Prop 65 warning. Running that calculation at incoming material receipt, against your actual ICP-MS lot data, takes about 30 minutes and can prevent a six-figure problem.

Building a Risk-Stratified ICP-MS Program That’s Actually Sustainable

The objection we hear from brands — especially smaller operations — usually centers on cost and turnaround time. Both are legitimate concerns. Full 24-element ICP-MS panels with arsenic speciation can run $150–$400 per sample depending on the lab, the element list, and whether IC-ICP-MS speciation is included. At high ingredient volumes, that adds up.

The practical solution is risk stratification, not blanket screening of everything or screening of nothing.

Prioritize ICP-MS testing on:

• Any Ayurvedic botanical — Ashwagandha, Shilajit, Triphala, Brahmi, Guggul, Amalaki, Trikatu, and all related materials
• Ingredients with known soil contamination risk tied to source region — certain root herbs, brown and red rice protein, kelp and other seaweeds
• New suppliers, regardless of ingredient category, for the first three lots minimum
• Established suppliers whose source geography may have shifted or who haven’t been tested in more than six months

For lower-risk ingredients from vetted suppliers with a documented track record of clean results, a reduced-frequency testing schedule with supporting supplier audit records is defensible under 21 CFR Part 111. The key word is defensible — you need a written risk-based rationale, actual test data supporting the reduced frequency decision, and a defined reassessment trigger (new lot, new source region, new supplier facility).

If FDA inspects your facility and questions your elemental impurity program, your response needs to show a systematic approach: a risk classification for each ingredient category, supporting ICP-MS data from a qualified laboratory, and defined retesting criteria. “The supplier said it was clean” is not a program under FDA’s interpretation of 21 CFR Part 111.

The broader point is this: Ayurvedic raw materials are not dangerous because they’re Ayurvedic. Many lots test clean. But the category carries structural risk factors — traditional processing claims, complex botanicals, variable sourcing geography, and supplier CoA practices that don’t map to US analytical standards — that make independent ICP-MS data from an accredited analytical testing laboratory a non-negotiable part of your incoming materials program. Get that data before the lot goes into production, not after a consumer complaint or a market surveillance action forces the question.

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Written by Nour Abochama, VP Operations, Qalitex | Quality Consultant, Ayah Labs. Learn more about our team

Ship your sample to our Chicago facility — get a Qalitex CoA in 5–7 days. Contact us

Related from our network

• ISO 17025 Accredited ICP-MS and Elemental Impurity Testing for Supplement Raw Materials — Qalitex Laboratories performs full USP <232>/<233> panels with validated methods for complex botanical matrices, with results issued under ISO 17025 accreditation.