Does zinc oxide cause cancer?

Why are there concerns about nanoparticles?

Nanoparticles are extremely small particles, less than 100 nanometres across. Mineral sunscreens can look opaque, and using smaller particles reduces that visible finish. The cosmetic aim is a less opaque sunscreen, not a compulsory white costume for going outside.2

Laboratory research has found that zinc oxide nanoparticles can damage cells and genetic material under some test conditions. Their behaviour depends on factors such as particle size, coatings, formulation and exposure to light. These findings raise questions about particle behaviour and product design, rather than identifying cancer as an expected result of applying zinc oxide sunscreen.23

Long term exposure and the stability of nanoparticle formulations remain areas for research. The safety assessment covers the coated and uncoated particles evaluated, not every possible future coating. New coatings need additional testing if they could change how particles penetrate skin.12

Does zinc oxide get into your body?

Zinc oxide nanoparticles do not appear to pass through the skin. A small amount of zinc dissolves out of the particles, and some of that dissolved zinc can be absorbed. The amounts involved are small compared with the zinc normally present in the body. Absorbing dissolved zinc is different from absorbing intact nanoparticles.1

Safety calculations account for this absorbed zinc rather than assuming that nothing enters the body. The estimated exposure from skin application falls within acceptable safety margins. Larger zinc oxide particles are also considered safe for use in sunscreen applied to skin, so choosing a product without nanoparticles is not necessary on cancer grounds.13

Are sprays different from creams?

Yes. Inhaling zinc oxide nanoparticles can cause lung inflammation and serious local lung effects. Products that spray these particles cannot be treated as having the same safety profile as sunscreen spread onto skin. Choose a cream or lotion to avoid the nanoparticle inhalation concern. Never apply a spray sunscreen directly to your face.134

What is zinc oxide's regulatory status?

In the United States, zinc oxide remains a permitted sunscreen active ingredient. The FDA's 2021 proposed sunscreen order also proposes classifying zinc oxide sunscreens as generally recognized as safe and effective. That proposed classification is separate from requests for more safety data on several other sunscreen ingredients. Those requests are not a finding that zinc oxide causes cancer.5

How should you use a zinc oxide sunscreen?

Use the product's label to identify its active ingredients and application directions, giving the small print a job beyond occupying the bottle.4

1. 1Choose a sunscreen labelled broad spectrum with SPF 15 or higher. Broad spectrum protection covers both UVA and UVB rays.
2. 2Apply 15 minutes before sun exposure. Cover exposed skin evenly, avoiding the eyes and mouth. Covering an entire adult body takes at least one ounce.
3. 3Reapply at least every two hours, and more often when swimming or sweating.
4. 4Use clothing and shade alongside sunscreen, and limit sun exposure between 10 a.m. and 2 p.m.