I was recently asked by someone with hair that tends to break and split what I thought of Redken's Extreme Anti-Snap Leave-in Treatment ($17.99). Before even looking at it, I was tempted to suggest that she just try emu oil, which has a proven track record for strengthening hair as well as waking up sleeping hair follicles. Having looked closely at Redken Extreme, I would now say that it would be probably safer to swim across the Hudson River than leave this product on your head. The Cosmetic Database seems to agree with, giving Redken Extreme the dubious honor of a nine out of ten hazard rating.

One of the culprits could be Arginine HCl. Arginine is an amino acid, but arginine hydrochloride is listed in the Cosmetic Database as a neurotoxin (although I couldn't find the studies cited) and, according to the Material Safety Data Sheet, is hazardous if in contact with the skin (this is at a pure concentration). Polyacrylamide is a polymer that is formed from units of acrylamide, a known neurotoxin. However, Polyacrylamide itself is not considered to be toxic, but is a controversial ingredient because of its potential ability to secrete acrylamide, according to Wikipedia. Although allowed by the FDA, concentrations used in cosmetics are limited.

There are several laureths in this product. The number (eg laureth-230 refers to the level of viscocity. However, there is some research that suggests that the higher the number, the more likely it is to cause irritation. Oleth-10 can be an irritant, increase the penetration of other products and be contaminated with carcinogens. Then there is a couple of parabens and  phenoxyethanol at number three in the ingredients list.

The few good things - wheat amino acids, taurine (an antioxidant) and soy protein - don't really stand a chance.

Ingredients

Water (aqua), Cyclopentasiloxane, Phenoxyethanol, Polyacrylamide, Dimethiconol, C13-14 Isoparaffin, Laureth 23, Laureth 4, Laureth 7, Methylparaben, Disodium EDTA, Ethylparaben, PPG-5-Ceteth-20, Hydrolyzed Soy Protein, Wheat Amino Acids, Arginine HCl, Taurine, Oleth 10, Disodium Cocoamphodipropionate, Lecithin, Hydroxypropyl Trimonium Hydrolyzed Wheat Protein, Phosphoric Acid, 2 Oleamido 1, 3 Octadecanediol, Trehalose.