Pyrrolizidine alkaloid (PA) testing measures a group of natural plant toxins that can damage the liver. The EU has set maximum levels for PAs in herbal teas, certain dried herbs and spices, and food supplements, in force since 2022, so most EU buyers now require the test.
Other buyers, especially UK and some US brands, ask for it too. Herbal tea packers are the most consistent about it.
Where PAs come from
A few plants make PAs themselves, such as comfrey and borage. Most PA problems in traded herbs come from weeds that grow in the same field and get harvested with the crop.
Weeds from genera such as Senecio, Heliotropium, Crotalaria and Echium are well known sources. A small number of weed leaves or seeds in a large lot can push the result over the limit. PAs are not removed by drying or sterilisation.
This makes PA risk a field and harvest problem. Hand weeding, careful collection and good cleaning reduce it. Testing tells you whether those steps worked.
How the test works
- The lab extracts the sample and measures PAs and their N-oxides by LC-MS/MS.
- Results are reported as the sum of a defined list of PAs, in micrograms per kg.
- The list of compounds counted is set by the EU rule, so ask the lab to report against that list.
- Fewer labs offer this test than offer pesticides, so check the lab's scope before you send samples.
- Turnaround is usually longer than routine tests. Build it into your first order timeline.
Which products are most exposed
Herbal and rooibos teas, and leafy culinary herbs such as oregano, have had many PA findings in Europe. The EU rules also cover some seed spices, such as cumin. Supplements made from PA-producing plants face their own limits.
Low-growing leaves, mechanically harvested crops and loosely cleaned cut herbs carry more risk. Seeds and leaves of a weed can also end up in powders, where you can no longer see them.
What to put in your contract
Limits and the list of products covered can change. Check the current EU rule on the European Commission's food safety pages, and ask your own customer what they require. Our guide to common quality issues with Indian herbs puts PAs alongside the other main risks.
- The PA limit for your product category and market, stated in the spec.
- PA testing on the approval sample and on each lot before shipment, at an accredited lab.
- The right to reject a lot that exceeds the limit, at the supplier's cost.
- A statement of how the crop is weeded, collected and cleaned.
How we help
We arrange PA testing at accredited labs on the actual lot, and visit the cleaning lines to see how weed material is removed. If a supplier has no PA history for a herb, we test before you commit to volume. Ask for a free sourcing review.