Taking “selfies” with a smartphone and posting photos of yourself on the social media has made many teenagers – and adults – obsessive about how they look. Among other things, it has induced adolescent girls (and boys!) to get their hair straightened with chemicals, including a solution called methylene glycol, which converts to formaldehyde gas after coming in contact with air.

Formaldehyde is a chemical toxin that has been linked to cancer because it can damage DNA. It is a compound of carbon, hydrogen and oxygen that takes the form of a colorless, sharp-smelling gas at room temperature. The term formalin refers to an aqueous solution of formaldehyde, which functions as both a preservative for various foods, cosmetics and as an industrial disinfectant.

Many construction materials, including pressed-wood products such as particleboards, plywood or fiberboards, might contain formaldehyde, which increases their toughness and tensile strength. 

Formaldehyde is also a common substance applied in the clothing and textile industries to increase the ability of crease-resistance and dimensional-stability of pure cotton or cotton blended fabrics. Hair straightening products are designed to break and reform the chemical bonds in keratin, the key structural protein in hair and nails.

An article that appeared two years ago in the International Journal of Cancer warned against the use by adolescents of hair straighteners because of the increased breast cancer risk, which is due to the fact that formaldehyde contains hormonally active and carcinogenic compounds. 

Adolescence may be a period of enhanced susceptibility of the breast tissue to exposure to chemicals. Health experts warn against the use of hair straighteners, especially for those under the age of 20. Hairdressers who use such chemicals on customers on a regular basis have developed chronic cough, pain, nausea, nose bleeds and other health problems. 

Scientists at the US Food and Drug Administration (FDA) said in 2016 that hair straighteners with formaldehyde were unsafe and agency lawyers started drafting rules for a proposed ban but it never happened. According to a report in The New York Times, “an FDA spokeswoman did not directly respond to questions about why the agency’s move to ban hair straightening products with formaldehyde stalled, saying only that the agency’s Center for Food Safety and Nutrition considered a rule “as one of several potential actions” and that the cosmetics division had shifted its attention to tattoo inks, talc and allergens in makeup.

Now, Harefuah – the monthly Hebrew-language journal of the Israel Medical Association, has published an article on the chemicals entitled “Hair Straightening – Not Straightforward.” Six physicians from three Israeli hospitals and Tel Aviv University’s Sackler Faculty of Medicine noted that “the rising popularity of hair straightening in younger ages has become a medical issue, since glycolic acid and formaldehyde may be present even in ‘formaldehyde-free’ labeled products.”

They found that eight percent of products claimed to be free of formaldehyde in fact contained methylene glycol that converts to formaldehyde gas after coming in contact with air.

The chemicals are inhaled and absorbed into the bloodstream causing oxidative stress and cytotoxic (damage to the cells) to the proximal tubule cells leading to acute kidney injury [AKI].”

The authors present case studies of three adolescent girls aged 13, 17 and 17.5 years with AKI soon after undergoing hair-straightening procedures. All of the three suffered damage to their tubule cells, resulting in kidney insufficiency. Biopsies in the first two cases showed acute tubular necrosis (dead tissues). Two of the teenagers had to undergo urgent kidney dialysis, which save the girls from permanent damage. 

The authors, from Wolfson Medical Center in Holon, Meir Medical Center in Kfar Saba, Ma’yanei Hayeshua Medical Center in Bnei Brak and TAU’s Medical Faculty warned that what they found “highlights the danger of hair-straightening products” in youngsters, and that this has increased suspicion among kidney specialists who treat youngsters – and adults – of the risks of their use. 

So kids – keep in mind that curls are no less beautiful than straight hair, and that if you must eliminate the curls, you can use any of the heated-air or “ironing” products that claim to straighten hair (but may cause physical damage to the strands).