UV/LED Lash Extensions: What the Science Actually Says

Regulatory facts

Official texts

• TPO, a photoinitiator, has been banned in European Union cosmetics since September 1, 2025, because it is classified as toxic for reproduction (category 1B) (European Commission, 2025).
• The European ban targets this molecule, not UV/LED technology (same source).
• In September 2025, Health Canada stated it had identified no risk related to TPO in nail products. TPO remains allowed in Canada (CTV News, 2025).
• In the United States, TPO is not on the FDA's list of prohibited or restricted cosmetic ingredients (FDA).

Measurements by a public body

A single source

• In 2024, the Finnish Radiation and Nuclear Safety Authority (STUK) measured six lash lamps. They emitted at 365, 395, 400 or 405 nm, with intensities varying up to 20-fold from one device to another (STUK, 2024).
• For the most powerful one, the exposure limit for an open eye would be exceeded in 15 seconds at 20 cm. According to STUK, the closed eyelid blocks at least 95% of the radiation aimed at the eye (same source).
• STUK concludes that the devices studied do not appear to pose a significant risk in beauty treatments, while warning that more hazardous devices may appear on the market (same source).

The eyes

• Her eyes stay open throughout the appointment, unlike the client's.
• For dental curing lights, a different device, light reflected from the illuminated surface was the operator's main source of exposure, and the daily limit for the retina could be reached during a normal working day (Labrie et al., 2011).
• An LED emits a narrow band that does not always trigger the natural reflex to look away (Labrie et al., 2011).
• Ordinary prescription glasses block neither blue light nor UV. Glasses designed to filter the wavelengths of the lamp in use are needed (Labrie et al., 2011); UV-only protection does not cover the visible part of a 405 nm lamp's output. STUK recommends safety eyewear (STUK, 2024).
• These glasses do not have to be dark. To block the light of a 405 nm lamp, the filter must cut out violet and blue, and the filters used with dental curing lights are mostly orange. In a study of 15 filters, even the least effective blocked at least 97% of the irradiance, but some blocked less well below 420 nm (Soares et al., 2017). It is therefore important to check that the glasses cover the wavelength of the lamp in use. No study has evaluated these glasses among lash technicians.

Hands and skin

• Her fingers pass under the lamp again and again. According to STUK, the dose accumulated over a working day can become significant, and gloves can protect against it (STUK, 2024).
• Cases of occupational contact allergy caused by eyelash extension adhesives have been published (Pesonen et al., 2012). Among hairdressers and beauticians, the risk of allergy to HEMA, an acrylate used in nail products, is nine times higher (Symanzik et al., 2022).
• Not all gloves protect equally. For methacrylate monomers in dental products, the breakthrough time across 14 medical gloves ranged from a few minutes to more than 2 hours (Lönnroth and Ruyter, 2002).

Breathing

• Two professionals who applied extensions several hours a day developed occupational rhinitis, and one of them asthma, confirmed by challenge testing. The main component of the adhesives was ethyl cyanoacrylate (Lindström et al., 2013).
• The authors conclude that small amounts of cyanoacrylate adhesive are enough to cause occupational asthma and rhinitis (Lindström et al., 2013). This also applies to UV adhesives that contain it, like two of the three adhesives examined above.

What to check before buying

• The filter's transmission curve: almost complete blocking at 405 nm, and ideally up to 420 nm or more. Some filters block less well below 420 nm (Soares et al., 2017). Glasses designed for dental curing lights reduce transmitted light below 500 nm to less than 1% (Labrie et al., 2011).
• An orange or amber tint guarantees nothing on its own: without a transmission curve, there is no way to know what the lens blocks.
• Ordinary prescription glasses block neither blue light nor UV (Labrie et al., 2011). “Blue light” lenses filter only part of it: in one study, they reduced the calculated risk to the retina by only 10.6% to 23.6% (Leung et al., 2017).

With prescription glasses or loupes

• Orange wraparound glasses worn over prescription glasses: the simplest option for reading glasses or progressive lenses.
• Prescription lenses with an orange filter, made by an optician, provided the filter covers the lamp's wavelength.
• Loupes with a fixed orange filter. Flip-up filters, common in dentistry, are poorly suited when the lamp switches on throughout the appointment.
• An orange face shield worn over loupes or glasses.

Day to day

• Through an orange filter, colours change: redness of the eye, skin irritation or coloured lashes are harder to see. Check the eye and skin without the glasses, under normal lighting and with the lamp off, at the end of the appointment.
• Wearing glasses over glasses or loupes for hours, with a mask that fogs them up, calls for comfortable, well-fitted frames.

Canada · Health Canada

• No approval before sale; each product must be notified to Health Canada (Health Canada).
• Cyanoacrylate extension adhesives: professional use only, with specific warnings (Health Canada, 2024).
• Ingredient list required on the label, using INCI nomenclature (Health Canada).
• TPO allowed as of the date of writing (CTV News, 2025).
• Anyone can report an incident to Health Canada (reporting form).

United States · FDA

• No approval before sale; facility registration and product listing mandatory under MoCRA (FDA).
• Products for professionals only: the label must state that they are to be administered or used only by licensed professionals (21 U.S.C. § 364e).
• Ingredient list required on cosmetics sold at retail to consumers; not on products used only by professionals at their place of business (FDA).
• TPO not on the list of prohibited or restricted cosmetic ingredients (FDA).
• Companies must report serious adverse events within 15 business days (FDA); anyone can report a problem through MedWatch (FDA).