Interesting...
Here's the abstract on "cetrimonium chloride":
FINAL REPORT ON THE SAFETY ASSESSMENT OF CETRIMONIUM CHLORIDE, CETRIMONIUM BROMIDE, AND STEARTRIMONIUM CHLORIDE
Abstract:
Cetrimonium Bromide, Cetrimonium Chloride, and Steartrimonium Chloride are quaternary ammonium salts used for a variety of purposes in cosmetics at concentrations of up to 10%. Cetrimonium Bromide given orally is poorly absorbed from the intestine and is excreted in feces. Cetrimonium Bromide applied dermally is absorbed into the skin, but not rapidly. Dermal irritation and sensitization and ocular irritation are seen with these quaternary ammonium salts. Cetrimonium Bromide was embryotoxic and teratogenic in mice following intraperitoneal injection of 35 mg/kg; only teratogenic effects were observed with 10 mg/kg. Embryotoxic effects consistent with maternal toxicity were seen in a rat-feeding study using 50 mg/kg/day. Dermal exposure to 2% Cetrimonium Chloride produced no evidence of teratogenicity; nor did 2.5% Steartrimonium Chloride. All mutagenesis assays used were negative. Repeated insult patch tests of concentrations of up to 0.25% Cetrimonium Chloride produced no sensitization reactions, although irritation was observed during induction. Based on the available data Cetrimonium Bromide, Cetrimonium Chloride, and Steartrimonium Chloride are considered safe for use in rinse-off cosmetic products but are safe only at concentrations of up to 0.25% in leave-on products.
(I guess the bottom line is that it's best if you rinse your hair daily, while using Surge)