Herbal Essences Long Term Relationship Shampoo for Long Hair contained a 1,4-dioxane level of 14 parts per million in a 2010 test by the Green Patriot Working Group.

Copyright 2010 Procter and Gamble. All rights reserved.

If you track toxins in personal care products like baseball fans track box scores, then you'll remember the hubbub last year when the Campaign for Safe Cosmetics announced results from lab tests finding a pesky little contaminant called 1,4-dioxane in a whole host of children's bath products.

Just in case you're saying "one, four, what?" let's review. 1,4-dioxane is a contaminant produced when manufacturers mix up batches of sodium laureth sulfate and other chemicals that give soaps and shampoos their foamy suds. The EPA considers it a "probably human carcinogen" and California includes it on the Proposition 65 list of chemicals known or suspected to cause cancer or birth defects. This isn't to say that lathering up with your favorite bubble bath or shower gel is going to cause cancer. But using these products does add a teensy dose of potential carcinogens to your average bath, which is already something of a toxic soup.

Here's the rub: since sudsy product makers didn't intend to put 1,4-dioxane into their formulas, they've been having a heck of a time trying to get it out. Which is why it's such exciting news that Proctor & Gamble has said it's reformulating its entire Clairol Herbal Essences line to be lower levels of 1,4 to less than 10 parts per million by the end of 2010 in response to pressure from environmentalists. Herbal Essences has long been the scourge of the eco-beauty movement, since it sounds so green (remember those coy commercials about having a "totally organic" shower experience?) but actually wasn't. Even a little bit.

So, kudos P&G and let's not stop there. "We're glad Proctor & Gamble is reducing the levels of 1,4 dioxane in its Herbal Essences line, but the company clearly has a much bigger problem," says Lisa Archer, national coordinator of the Campaign for Safe Cosmetics from the Breast Cancer Fund. "Proctor & Gamble needs to show it cares about all its customers by eliminating this carcinogen from all its brands." In fact, when environmentalists announced the P&G news at a press conference on Friday, they also released new testing that found several P&G brands of laundry detergent (Tide, Tide Free and Ivory Snow) still contain pretty high levels of 1,4-dioxane. Oops.

Meanwhile, if you want a truly green shower experience, check out our top green shampoo picks and learn how to make your own shampoo and conditioner at home.