Heavy metals and pesticide residues: what botanical buyers should test for

Botanicals are agricultural products. They accumulate what is in the soil, the water and the spray programme — which is why contaminant testing, not appearance, is the real measure of a clean ingredient.

The four heavy metals

Lead, arsenic, cadmium and mercury are the standard panel. Limits vary by market and by product category, and some jurisdictions apply stricter thresholds to products intended for children or for daily long-term use.

Rather than accepting a supplier's default limits, specify the thresholds your destination market requires and make conformance a release condition.

Pesticides: the panel matters more than the pass

"Pesticide compliant" means very little without knowing which panel was run. A narrow screen can miss residues that are actually likely for that crop and region.

Ask for the panel list, and confirm it covers the actives realistically used on that botanical at origin. For organic-certified material, residue testing still matters — certification governs process, not outcome.

Microbiology and mycotoxins

• Total plate count, yeast and mould — general hygiene indicators.
• E. coli and Salmonella — pathogen absence, typically per 25 g.
• Aflatoxins — relevant for several botanicals, particularly where drying conditions are variable.

How often to test

Lot-by-lot testing for release-critical parameters is the defensible position. Periodic verification of a wider panel — annually, or on supplier change — catches drift that routine testing is not designed to find.

Keep the paperwork aligned

Your purchase specification, the supplier's COA and your own incoming-goods checks should reference the same parameters, the same methods and the same limits. Where those three documents disagree, disputes become expensive.