Heavy Metals & Trace Contaminants

In short

Heavy metals — lead, cadmium, arsenic, mercury — accumulate in animal tissues and are regulated in feed materials, with mineral sources and marine ingredients carrying the highest inherent risk.

Measured as: mg/kg (ppm) by ICP-MS or ICP-OES after digestion; speciation for inorganic arsenic where required

Risk concentrates in mineral and marine inputs

Phosphates, trace mineral salts, limestone and marine proteins are the usual entry points for heavy metals into a feed chain. Plant materials generally carry lower loads, though cadmium in some phosphate-fertilised crops and soils is a known exception.

Cumulative exposure is the regulatory concern

Regulators set limits on complete feed as well as feed materials because exposure accumulates across many small contributions. A compliant individual ingredient can still push a complete diet over the limit when several inputs sit near their maxima.

What to verify

—Certificate values for lead, cadmium, arsenic and mercury against destination limits
—Whether arsenic is reported as total or inorganic
—Contribution calculation at complete-feed level, not only per ingredient
—Supplier's raw-material origin and mining or fishery source consistency

Typical risks

—Residues in eggs, milk and meat
—Import rejection and product recall
—Cumulative exceedance at complete-feed level

Common mistakes

—Testing only the finished feed
—Accepting a generic certificate not tied to the delivered lot

Frequently asked questions

How often should heavy metals be tested?

Risk-based: every lot for high-risk mineral and marine inputs from new sources, then a reduced frequency once a supplier's statistical history is established, with periodic verification retained.