A consumer-advocacy business sent one retail unit of a 40% zinc oxide diaper rash ointment to an independent laboratory. The laboratory analysed it by ICP-MS for lead, cadmium, mercury and arsenic. Lead was 3303.8 ppb and cadmium 55.50 ppb as received. Arsenic and mercury were below the reporting values. The report is appended to a blog article. The product’s brand is named only in the printed title of the article and the laboratory report annotation.
Key numbers
The laboratory report (Purity Laboratories, Inc., Lake Oswego, Oregon; case 2507151; received 07/10/2025, tested 07/14/2025, completed 07/15/2025) prints one result per analyte, in ppb, with the method stated as ICP-MS. The sample description sent to the laboratory was an anonymised label with lot number 2025-142. The advocate’s annotation identifies the product as a 40% zinc oxide maximum-strength diaper rash paste.
| Analyte | Result (ppb, as received) | Note |
|---|---|---|
| Lead | 3303.8 | detected |
| Cadmium | 55.50 | detected |
| Arsenic | < 10.00 | below reporting value; not speciated |
| Mercury | < 5.00 | below reporting value; not speciated |
The article restates the lead result as “3,303.8 parts per billion Lead, which is more than 3 parts per million”. It compares the result with a 1 ppm (1,000 ppb) lead limit in the Washington State Toxic-Free Cosmetics Act and with a 10 ppm federal figure for cosmetics. Neither instrument is in this collection.
Methods (brief)
The report states only the analyte, unit, result and method (ICP-MS). It does not report sample mass, digestion procedure, calibration range, recovery, duplicate analysis, a detection limit distinct from the reporting value, or laboratory accreditation. The footer says the results apply to the sample as received, so the basis is the finished product as sold. Arsenic and mercury are totals. The article describes the testing as community funded and gives no chain-of-custody record.
Evidence fitness
The report supports one statement: this unit of this 40% zinc oxide ointment contained total lead at 3303.8 ppb and total cadmium at 55.50 ppb as received. It is consistent with the other advocate reports in this collection, which found lead above 1,000 ppb in every zinc oxide product with a laboratory report in the package. It does not establish how much lead or cadmium reaches or crosses infant skin. One unit cannot describe the product line, the brand or the category.
Limitations
This is a single sample from a single lot, chosen by an advocate and analysed without published quality-control data. The product name in the article (“Extra Strength”) differs from the laboratory annotation (“Maximum Strength Paste”). The annotation is used here because it sits on the report itself. The article’s legal statements are the author’s. They conflict with statements on the author’s later pages, and the Washington statute and the FDA cosmetics lead guidance were not in the package. The ’<’ results are reporting values, not measured concentrations.
Related evidence
- Diaper Cream, ZnO-Based
- Consumer-advocacy comparison chart of lead, cadmium, mercury and arsenic in eleven diaper creams (updated January 2026)
- 21 CFR Part 347, Skin protectant drug products for over-the-counter human use (4-1-25 edition)
- Lead
- Cadmium
Update history
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