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 arsenic (As) (inorganic As reference dose used for the risk step).
Per-serving concentration ranges, Consumer Reports set (Table 1):
| Type | As (µg) | Cd (µg) | Pb (µg) | Hg (µg) |
|---|---|---|---|---|
| Whey protein (n=11) | 0.40–1.80 | ND–1.30 | ND–1.63 | ND–0.37 |
| Weight gainer (n=4) | 3.73–5.63 | ND–1.87 | ND–4.50 | ND–0.23 |
Per-serving distribution, Clean Label Project set (n=133, Table 3):
| Metric | As (µg) | Cd (µg) | Pb (µg) | Hg (µg) |
|---|---|---|---|---|
| Median | 0.55 | 1.44 | 0.08 | 0.61 |
| 95th pct | 2.17 | 6.84 | 0.21 | 2.26 |
| Max | 3.42 | 13.18 | 0.97 | 5.31 |
- Per-serving concentration order (Clean Label Project mean): cadmium (Cd) > mercury (Hg) > As > lead (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 inorganic arsenic (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.
Update history
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