Silky smooth hair has been sought after for years, so it's no surprise that people from Japan and Brazil have come up with their own ways to more permanently iron out frizzy tresses. Brazilian hair straightening treatments and Japanese hair straightening treatments have become popular recently, but when it comes to hair straightening and relaxing, what is effective and safe?

Japanese hair straighteners are permanent. In fact, they work on breaking and rearranging the internal bonds of hair so that when the process is complete, your hair is permanently straightened out. A chemical by the name of thioglycolate is usually used for this thermal process; it will break the cystine proteins which are present in the cortex layer of the hair shaft. Once those are broken down, hair can be any desired shape.

However, this also means that the new growth will be your original curly hair, and that growing out process will be a lot like having to upkeep highlights. A head of half-curly half-stick straight hair doesn't sound very appealing. Plus, this process could be damaging if the chemicals are left on too long, and that damage to hair is irreversible. Many say that after several Japanese hair straightening treatments the luster of your hair is affected, too.

The Brazilian hair straightening treatment alternative has been controversial for its own set of reasons. Though the Brazilian straightening process requires an application of active keratin, a protein found in the top layer of our skin and hair that makes it strong, it is often used in conjunction with formaldehyde for semi-permanent straightening results. The Brazilian hair straightening treatment formula is sealed into the hair using heat. Some experts say it is likely that the formaldehyde chemicals break hair's disulfide bonds and change its shape. And in the UK, the Cosmetics, Toiletries and Perfume Association recently reported that some products contain up to 10% formaldehyde (the limit under the UK Cosmetic Products Safety Regulations is only 0.2%), meaning some Brazilian hair straightening treatments are using dangerous levels of these chemicals.

Formaldehyde is scary, to say the least; it is on the Department of Health and Human Services' "reasonably anticipated to be human carcinogens" list, and has been linked to cancers like leukemia. The Cosmetic Ingredient Review (CIR) Expert Panel does list formaldehyde as "safe as used" in cosmetics within certain specifications from research done in 1984, but these specifications include using it in quantities of less than 0.2 percent. An investigative article in Allure from 2007 tested three salon samples of individual Brazilian hair straightening solutions, only to find that all three of the formaldehyde levels were in excess of the recommended .2 percent limit.

According to one study in a 2010 Toxicology Science Journal, inhaled formaldehyde is classified as a known human and animal carcinogen, causing nasopharyngea cancer. Brazilian hair straighteners are applied to the hair and heated with a flat iron, vaporizing the formaldehyde and releasing it into the air. According to the Professional Beauty Association, both stylists and clients can be exposed to levels of formaldehyde greater than 0.75 ppm by inhaling these vapors. Another study showed that the chemical in Brazilian hair straightening treatments has mutagenic risks. Doesn't that seem to be too toxic of an occupational hazard to mess with?

There are some formaldehyde-free options, though, which range from completely hyde-free, to moderate levels of organic aldehydes. Among them is Brocato's Curlinterrupted Keratin Smoothing System which claims to be a formaldehyde-free, thio-free, sodium hydroxide-free, keratin-based hair straightening solution.

But some argue that formaldehyde-free doesn't equate to completely safe either. Cosmetic chemist Ron Robinson of beautystat.com says aldehyde is from the same family of organic compounds. Aldehyde and formalin are derivatives or chemicals in the same family, which means they still produce similar noxious gases and require the use of face masks and ventilation during processing. Common "formaldehyde-free" products also often contain glutaraldehyde, biformal (oxalaldehyde) and ammonium thioglycolate. None of these chemicals are squeaky clean.

In the fight against frizzy curls, Brazilian hair straightening does seem to be an appealing method on the surface. But given the high risk involved, it is a little too toxic to ignore the dangers.

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