PAH Contamination in Botanical Raw Materials: The Gap on Your Incoming COA

A green tea extract clears every test on the standard receiving panel. Identity confirmed by HPTLC. Heavy metals well below USP <232> limits. Microbial counts compliant. The certificate of analysis looks clean, and the raw material moves into production.

Six months later, the same lot gets tested by a European distribution partner. Benzo[a]pyrene: 28 µg/kg. Under EU Commission Regulation (EC) No 835/2011, the limit for dried herbs and herbal preparations is 10 µg/kg. The product is blocked at the border. The brand’s European expansion stalls for a full quarter while they work backward through the supply chain.

This isn’t a hypothetical scenario. PAH contamination in botanical raw materials is documented, measurable, and — this is the part that stings — entirely predictable if you know what to look for. But it almost never appears on a standard incoming COA.

Why PAHs Form in Botanical Supply Chains

Polycyclic aromatic hydrocarbons are a family of fused-ring organic compounds produced during incomplete combustion of organic matter. The EPA has designated 16 “priority” PAH compounds for environmental monitoring purposes, but food and supplement regulatory frameworks focus on a subset of four: benzo[a]pyrene, benz[a]anthracene, benzo[b]fluoranthene, and chrysene. These four are collectively called PAH4. IARC classifies benzo[a]pyrene as a Group 1 carcinogen — definitive evidence of carcinogenicity in humans — and the remaining PAH4 markers fall between Groups 2A and 2B.

Botanical raw materials accumulate PAHs through two distinct routes.

The first is process-related. A substantial portion of the world’s dried herb supply — particularly from China, India, and parts of Southeast Asia — is still dried using direct flame or smoke contact. Open biomass burning, charcoal kilns, and wood-fired drying chambers deposit PAH compounds directly onto plant material. The practice is efficient and cheap, and it has been the dominant drying method in many growing regions for generations. Green tea, rosemary, black tea, rooibos, astragalus, and a wide range of root-based ingredients are regularly processed this way. The resulting PAH4 levels can exceed EU limits with no obvious indicator at intake.

The second route is environmental. Plants grown near industrial zones, high-traffic roadways, or areas with chronic atmospheric particulate deposition absorb PAHs through root uptake and surface deposition on leaves and stems. Botanicals from certain growing regions in East Asia have shown elevated PAH profiles in peer-reviewed studies even when no smoke-drying was involved. The soil carries it. The air carries it. The plant concentrates it.

Neither pathway produces any visible signal in a standard incoming identity screen or a routine heavy metals panel.

The Regulatory Landscape — and the Gap U.S. Brands Are Operating In

The EU has had specific PAH limits for botanical ingredients since 2011. Under EC No 835/2011 and its subsequent amendments codified in EU 2015/1933, dried herbs, herbal infusions, and food supplement ingredients are subject to the following enforceable limits:

• Benzo[a]pyrene: ≤ 10 µg/kg
• PAH4 sum: ≤ 50 µg/kg

These aren’t guidance values — they’re hard limits. Non-compliant products are blocked and reported through the EU’s Rapid Alert System for Food and Feed (RASFF). PAH exceedances in botanical raw materials appear in those RASFF notifications regularly enough that European importers now routinely request PAH4 data as part of supplier qualification. Many U.S. brands first encounter this requirement when a European buyer asks for it and they realize they’ve never tested.

FDA tells a different story. There are no specific PAH limits for dietary supplement ingredients under 21 CFR Part 111 or elsewhere in current federal regulations. The general adulteration provisions of DSHEA — section 402(a)(1), which covers adulteration by any poisonous or deleterious substance — could theoretically apply, but FDA has not published action levels for PAHs in botanical raw materials. For brands selling only domestically, this feels like a non-issue.

Two real-world exposure vectors suggest otherwise.

California Proposition 65. Benzo[a]pyrene is listed under Prop 65 as a known carcinogen. The No Significant Risk Level (NSRL) — the daily exposure threshold below which no Prop 65 warning is required — is 0.062 µg per day. A supplement containing a botanical ingredient at 20 µg/kg benzo[a]pyrene, dosed at two grams daily, delivers 0.04 µg of benzo[a]pyrene per serving. That’s uncomfortably close to the Prop 65 NSRL, and any serving size above that or any higher contamination level crosses it. Brands doing business in California without PAH data on their high-risk botanicals are accepting Prop 65 exposure they may not be aware of.

Retail and export channel requirements. Whole Foods, Costco, major European distributors, and a growing number of Amazon marketplace gatekeepers require third-party testing data against international food safety benchmarks. A brand without PAH documentation can’t certify compliance to these buyers. And discovering non-compliance after you’ve printed labels and filled a production run is substantially more expensive than running the screen before accepting the raw material.

How Analytical Testing Laboratories Detect PAHs in Botanical Matrices

Not every analytical testing laboratory offers PAH analysis, and not every one that does runs it well. Method selection and sample preparation are where the quality gaps tend to emerge.

The gold standard for PAH screening in complex botanical matrices is GC-MS/MS — gas chromatography tandem mass spectrometry. The tandem mass spectrometry stage provides the selectivity needed to resolve individual PAH compounds from the dense chemical background typical of plant extracts. Detection limits by GC-MS/MS routinely reach 0.1 µg/kg for individual PAH compounds — well below both EU regulatory thresholds and the Prop 65 NSRL calculation range.

HPLC with fluorescence detection (HPLC-FLD) is an acceptable alternative for PAH4 marker screening specifically. Fluorescence detection is highly sensitive for aromatic ring compounds, and HPLC-FLD is sometimes preferred for high-throughput screening when confirmatory GC-MS/MS is available for positives.

Sample preparation is where laboratories differ most significantly. Botanical matrices — especially lipid-rich materials like black seed, saw palmetto, or standardized herbal oleoresins — require solvent extraction followed by solid-phase extraction (SPE) cleanup to remove co-extractants that otherwise interfere with PAH quantification. An analytical testing laboratory that skips proper cleanup steps will generate unreliable results: inflated false positives from matrix interference, or suppressed signals that miss real contamination. When vetting a laboratory for PAH work, ask specifically about their extraction and cleanup protocol before you submit samples.

Accreditation provides a useful shortcut here. ISO 17025-accredited analytical testing laboratories that list PAH analysis within their scope of accreditation have had that specific method reviewed and verified by an independent assessory body. That’s a meaningful difference from a lab that will “run PAHs if you request it” without any documented method validation.

Building a Risk-Tiered PAH Testing Program

Not every botanical ingredient carries the same PAH risk. A practical program tiers raw materials by source geography, documented processing method, and botanical type — then sets testing frequency accordingly.

Tier 1 — test every incoming lot:

• Green and black tea extracts, regardless of supplier claim
• Rosemary, sage, and other aromatic herbs from Mediterranean or Asian origins where smoke-drying is common
• Root-based adaptogens from East Asian supply chains: astragalus, codonopsis, rehmannia, eleuthero
• Any ingredient where the supplier cannot provide documented evidence of the drying method used
• Botanicals with a prior RASFF notification history

Tier 2 — test first lot per supplier, then screen annually:

• Herbs from growing regions with documented industrial air pollution
• Standardized extracts where the extraction solvent and process aren’t independently verified
• Any ingredient where the supplier is new and has not yet been qualified through an audit or reference testing

Tier 3 — baseline screen at supplier onboarding, then monitor by exception:

• Certified organic botanicals from EU, North American, or Australian origins with documented process controls
• Materials with a long-term, audited supplier relationship and consistent clean prior results

The tiering logic is straightforward. It channels analytical resources toward the highest-risk materials while still ensuring that every supplier has demonstrated PAH compliance at least once before you put them on your approved list.

One operational note that gets missed regularly: supplier-provided COAs almost never include PAH data unless you ask for it — and include PAH4 limits in your raw material specification. If PAH testing isn’t in your specification, the supplier has no obligation to test for it. Build it in as a line item. If a supplier pushes back or claims PAH data isn’t available, treat that as a qualification concern, not a paperwork issue.

What Midwest Brands Should Do With This Information

Most supplement brands operating out of Chicago, the broader Midwest, or anywhere in the DSHEA-governed U.S. market are buying botanical raw materials on standard commodity terms. The COA checks a defined box. Identity, heavy metals, microbiology — those are the standard gates because they’re what 21 CFR Part 111 explicitly addresses. PAHs fall into the category of tests that get added after something goes wrong.

The cost of adding them proactively is modest. PAH4 screening by GC-MS/MS typically runs $150–$250 per sample depending on the laboratory and turnaround time required. Against the cost of a blocked export shipment, a Prop 65 notice, or a retail buyer rejection, that calculation isn’t close.

The brands building durable supplier qualification programs — the ones that can credibly market into EU-adjacent channels, respond to safety questionnaires with documented data, and defend any future regulatory scrutiny — are the ones who’ve already made PAH testing a standard part of their receiving workflow. It’s not a premium option. It’s closing a gap that’s been sitting open in most receiving protocols since the ingredient was first sourced.

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

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• ISO 17025 Supplement Testing at Qalitex Laboratories — Accredited analytical testing for dietary supplements, botanicals, and raw materials, with full CoA documentation for DSHEA and international compliance.