Zinc oxide
What it is
Zinc oxide is a mineral compound and the FDA-recognized active ingredient in most diaper-rash ointments and mineral sunscreens — it forms a physical barrier on skin and has a long safety record at the concentrations those products use. The ingredient itself is not the concern; the concern is contamination. Zinc oxide is refined from zinc ore, and depending on the ore source and refining process, trace heavy metals — lead, cadmium, arsenic — can carry through into the finished ingredient if a supplier's purification isn't tight.
Why it's flagged
Independent testing of zinc-oxide-containing products has moved from occasional spot-checks to a sustained, product-by-product pattern of positive results. Between mid-2025 and early 2026, an ongoing independent ICP-MS testing initiative (Lead Safe Mama, using Purity Labs) tested a series of name-brand zinc-oxide diaper-rash creams and ointments and found detectable lead in essentially every one — including several marketed as "clean" or EWG Verified. The contamination traces to the raw zinc oxide feedstock, not to zinc oxide as a chemical: zinc ore naturally co-occurs with lead, cadmium, and arsenic, and how tightly a refiner purifies the zinc oxide before it reaches a formulator determines how much of that trace metal carries through. Heavy metals of this kind don't have a recognized safe exposure floor for a developing child in the way some ingredients do, so even trace contamination is treated as worth avoiding rather than tolerating. These specific test results are not evidence of a legal violation — U.S. federal cosmetics rules don't set a binding lead limit these products exceed — which is a meaningful distinction from a recall; see "how concerned to be" for what these numbers do and don't mean.
How concerned to be
Use with caution, and check the specific product before assuming "zinc oxide" alone tells you anything. Pharmaceutical- and cosmetic-grade zinc oxide from a reputable manufacturer can meet purity specifications (typically USP or equivalent) that cap heavy metal content at trace levels — but independent testing across 2025-2026 found detectable lead in nearly every zinc-oxide diaper-rash cream tested regardless of price or "clean" marketing, with several results exceeding Washington State's new cosmetic lead limit of 1 part per million (1,000 ppb, effective January 2025) by three to four times over. FDA's own cosmetic lead guidance — a non-binding 2016 draft recommendation, not an enforceable limit — puts a recommended maximum around 10 ppm (10,000 ppb), so these results sit well under federal guidance while still exceeding the stricter state standard; that gap is exactly why "not illegal" and "not detected" are different claims, and why a brand can legally sell a product that independent testing flags as concerning. One non-zinc alternative (a plain petrolatum-based balm, tested by the same initiative) came back non-detect for lead, cadmium, mercury, and arsenic — proof the contamination isn't inherent to treating diaper rash, only to this specific supply chain. See our diaper-rash-cream category page for product-by-product results.
What it's called on a label
Look for any of these on an ingredient list: ZnO, Zinc oxide.
Sources
- Heavy Metals in Cosmetics: A General Overview, U.S. Food and Drug Administration (2023)
- Zinc Oxide Monograph, United States Pharmacopeia, USP–NF (2024)
- Limiting Lead in Cosmetics (non-binding draft guidance, recommended maximum 10 ppm), U.S. Food and Drug Administration (2016)
- Toxic-Free Cosmetics Act compliance guidance (1 ppm lead limit, effective January 2025), Washington State Department of Ecology (2025)
- Independent, Third-Party Laboratory Testing of Zinc-Oxide Diaper Rash Creams and Ointments for Lead, Cadmium, Mercury, and Arsenic (Community-Collaborative Testing Initiative), Lead Safe Mama (Tamara Rubin) (2025)