"Nanoplasty" (also written nanoplastia, nano plasty, nano keratin, "acid progressive" or "progressive brush") is a salon hair-straightening treatment that's been quietly replacing the old Brazilian-blowout / keratin smoothing systems since around 2018. The product is a thick cream the stylist paints onto your hair, blow-dries in, and then seals with a flat-iron at 200–230 °C.

Underneath the marketing — "nano-sized actives", "amino acid technology", "formaldehyde-free", "natural keratin" — there is one active chemistry doing the actual straightening: glyoxylic acid (CHO-COOH), or one of its close cousins (ethyl glyoxylate, glyoxyloyl carbocysteine, glyoxyloyl keratin amino acids). Cosmetic chemists at the University of Bologna proved this in 2014 and it has been re-confirmed in every analytical paper since.

Glyoxylic acid is a small molecule with two reactive ends. Under heat, the aldehyde end reacts with the amino-acid side chains (lysine, arginine, cysteine) in your keratin to form permanent imine cross-links. That is exactly the same bond-forming chemistry as formaldehyde — only the carrier molecule is bigger. There is nothing "nano" and nothing fundamentally new about it.

The honest answer is: no, not as currently marketed. Here's the recent evidence, in plain language, with the journal name in brackets so you can verify it.

1. Salon air contains formaldehyde — even from "formaldehyde-free" products

Independent forensic chemists at the University of Brasília (Brazilian Journal of Pharmaceutical Sciences, 2022) tested ANVISA-seized smoothing creams by headspace GC-MS. The majority of "formol-free" / nanoplastia samples contained formaldehyde well above the 0.2 % legal preservative limit. A separate Nature Scientific Reports paper (2023) describes the modern method labs now use to detect that formaldehyde at parts-per-billion in cosmetic matrices.

The US FDA proposed a federal ban (RIN 0910-AI83, 2023; re-affirmed 2024) on formaldehyde and formaldehyde-releasing ingredients in hair-smoothing products specifically because salon air-monitoring exceeded OSHA short-term limits — even when the bottle said "formaldehyde-free".

2. Nanoplasty can cause acute kidney injury

This is the newest and most serious finding. Glyoxylic acid is metabolised in the body to oxalate, which crystallises as calcium oxalate in the kidney tubules — the same mechanism as ethylene-glycol poisoning.

• Piras et al., Kidney International (2024). A single scalp application of a commercial nanoplasty cream produced acute tubular injury and oxalate crystals in mice within hours. The paper's title is literally "Hair-straightening cosmetics containing glyoxylic acid induce crystalline nephropathy."
• Tabibzadeh et al., American Journal of Kidney Diseases (2023).Case series of 26 women hospitalised with otherwise-unexplained acute kidney injury within 24–48 h of a glyoxylic-acid salon treatment.
• Khan et al., World J. Nephrology (2025) systematic review.Pools 40+ published AKI cases worldwide and concludes the link is causal.
• ANSES (France), January 2025 opinion. Recommends an EU-wide restriction of glyoxylic acid and its derivatives in cosmetic hair products on the basis of this renal-toxicity evidence.

3. It physically damages your hair — measurably

Cosmetic chemists at the University of São Paulo (Velasco et al., International Journal of Trichology, 2023) put acid ("progressive brush" / nanoplasty-type) treatments through microscopy and mechanical testing. After a single application they measured visible cuticle lifting and chipping under scanning electron microscopy, and a reduction in break-stress — meaning the fibre is measurably weaker and more brittle, not stronger. A 2024 USP Master's thesis (Bandeira) extended this with FT-IR, confirming the chemical modification of the cortex is permanent: it grows out, it does not wash out.

No. ANSES, ANVISA and the EU Scientific Committee on Consumer Safety (SCCS) all advise against aldehyde-based hair smoothing during pregnancy and breastfeeding. Two reasons:

• Formaldehyde is classified Group 1 — carcinogenic to humans by IARC, crosses the placenta and is mutagenic.
• Glyoxylic acid → oxalate metabolism uses the same pathway implicated in paediatric ethylene-glycol poisoning. Pregnant women and infants have less renal reserve and higher dermal absorption per kg of body weight.

There is no peer-reviewed safety data that supports a "safe-during-pregnancy" claim for nanoplasty. If a salon tells you it's fine, ask them which study they're quoting. There isn't one.

No. Children have thinner skin, smaller kidneys, higher breathing rates relative to body weight, and longer life-expectancy over which any DNA damage from formaldehyde can accumulate. The same agencies that flag pregnancy also flag paediatric use. A "softer" or "kids' version" of nanoplasty does not exist in the peer-reviewed literature — only in marketing.

When a glyoxylic-acid cream is sealed with a flat-iron, aerosols and vapours containing formaldehyde, methylene glycol and glyoxal enter the stylist's breathing zone. NIOSH and OSHA workplace limits (0.75 ppm 8-hour TWA, 2 ppm 15-min STEL) are routinely exceeded during these services, even when the product is labelled "formaldehyde-free". IARC classifies formaldehyde as causing nasopharyngeal cancer and myeloid leukaemia.

If you are a stylist offering nanoplasty: a proper fume extractor at the source, an FFP3 / P2 respirator (not a cloth mask), and limiting back-to-back smoothing services are the minimum. A cracked salon window is not ventilation.

A traditional SFH Original Keratin Hair Treatment uses a low, legally-declared formaldehyde level (≤ 0.2 %) as a fixative for a real keratin + collagen coating, with a full INCI list, mandatory PPE, and explicit contraindications for pregnancy, breastfeeding and children. It coats the cuticle, washes out gradually over 4–6 months, and does not chemically cross-link the cortex.

That is not the same chemistry as nanoplasty, and it is not the same risk profile. The honest answer for most clients — especially anyone pregnant, breastfeeding, under 18 or with kidney issues — is to wait, use a frizz-control wash-out treatment, or use a properly-labelled, properly-ventilated low-formaldehyde keratin service rather than a glyoxylic-acid nanoplasty.