A human health risk assessment of heavy metal ingestion among consumers of protein powder supplements

Summary

This peer-reviewed risk assessment characterizes arsenic, cadmium, lead, and mercury in protein powder supplements and models the resulting consumer exposure. The occurrence inputs are secondary — re-analyzed from two US third-party testing datasets (Consumer Reports 2010, n=15; Clean Label Project 2018, n=133), both reported here in anonymized form (sample type, not brand). For the Heavy Metal Index the load-bearing findings are that cadmium carries the highest mean per-serving concentration across the Clean Label Project products, that weight-gainer type powders run higher in arsenic and cadmium than whey-protein type powders, and that the authors’ cumulative hazard index stays below 1 for essentially all products except a single high-cadmium outlier (13.18 µg/serving), where three daily servings push the hazard index above 1. All modeled blood lead levels stayed below the CDC 5 µg/dL guidance value. The authors attribute the metal burden to plant-derived and milk-whey ingredients, consistent with cadmium and arsenic tracking with plant and dairy inputs. The practical contribution is a category-level occurrence and exposure picture for protein/collagen powders, with cadmium as the analyte to watch and weight-gainers as the higher-burden sub-type.

Key numbers

Concentrations are reported by the source as micrograms per serving (µg/serving), not per kilogram; serving sizes ranged ~20–79 g (powders) for the Consumer Reports set and were assumed at 43 g for the Clean Label Project set. Total metals; arsenic is total As (inorganic As reference dose used for the risk step).

Per-serving concentration ranges, Consumer Reports set (Table 1):

Per-serving distribution, Clean Label Project set (n=133, Table 3):

• Per-serving concentration order (Clean Label Project mean): Cd > Hg > As > Pb.
• Weight-gainer powders carried significantly higher As (and higher, non-significant, Cd and Pb) than whey powders.
• Cumulative hazard index < 1 for all products under 1 serving/day; the only HI > 1 scenario was the single 13.18 µg/serving cadmium product at 3 servings/day.
• Highest modeled blood lead level 2.24 µg/dL (1.50 µg/dL from the Clean Label Project set) — all below the CDC 5 µg/dL guidance.
• For context the authors cite USP 2012 elemental-impurity PDEs (As 15, Cd 5, Pb 10, Hg 15 µg/day); one Consumer Reports product’s As intake (16.9 µg/day at 3 servings) exceeded the USP As PDE.

Methods (brief)

Secondary risk assessment. Chronic daily intake = concentration × daily intake rate; hazard quotient = CDI / reference dose (US EPA RfDs for iAs, Cd, Hg); hazard index = sum of HQs; adult blood lead via the EPA Adult Lead Methodology (baseline BLL 1.27 µg/dL, 20% GI absorption). No new laboratory measurement; metal concentrations taken from Consumer Reports (2010) and Clean Label Project (2018) third-party testing.

Implications

• Contributes a cadmium-led occurrence and exposure signal for Ingredient class — protein/collagen powders, with weight-gainer powders as the higher-burden sub-type — useful for any future certification framing of this category.
• Reinforces Cadmium as the protein-powder analyte of concern and provides Arsenic, Lead, and Mercury per-serving context for the category.
• The plant-and-dairy-ingredient attribution links this back to the cadmium-in-cereals/plant pattern seen elsewhere in the corpus.

Wiki pages this source may touch

• Ingredient class — protein/collagen powders — As/Cd/Pb/Hg per-serving distribution; weight-gainer vs whey split.
• Cadmium — highest mean per-serving metal; high-Cd outlier driving HI > 1.
• Arsenic, Lead, Mercury — category per-serving context.

Verification notes

• Concentrations from Table 1 (Consumer Reports per-sample) and Table 3 (Clean Label Project distribution). The underlying products are anonymized by the authors (sample ID and type only), so no brand-by-brand data is reproduced and the Part 12 firewall is satisfied at the source.
• Occurrence is SECONDARY: the per-serving concentrations are re-analyzed from Consumer Reports and Clean Label Project third-party testing, not measured by the authors. Treat as B-quality occurrence input for pooling (down-weight versus primary ICP-MS surveys) even though the source journal is peer-reviewed (A-tier); the exposure/hazard modeling is the paper’s primary contribution.
• Units are µg per serving, not µg/kg — serving sizes vary (and were assumed at 43 g for the Clean Label Project set), so per-mass concentration must be derived if needed and is not stated directly.
• Speciation: total As reported; inorganic-As RfD applied only in the hazard step. Total Hg reported.

Update history

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