Keeping Well-preserved

Cosmetics ingredients must be above suspicion. As with Julius Caesar and his wife, even the hint of scandal is enough to precipitate a divorce—be it between man and woman or between cosmetics maker and suspect ingredient.

Cosmetics formulators have used esters of p-hydroxybenzoic acid as preservatives for more than 20 years. They are reliable and cost-effective, and most regulatory agencies and oversight bodies have approved their use. The tiniest amount of these preservatives keeps skin creams, shampoos, conditioners, and similar products free of bacteria, mold, and other contaminants.

But despite their long years of service, these preservatives, widely known as parabens, have raised a few eyebrows recently. Some cosmetics makers have either cut out parabens and switched to alternative preservatives or are moving in that direction largely because of two small studies.

The first appeared in the Journal of Applied Toxicology [2004, 24, 5] about two years ago. Researchers studied breast tumors from 20 patients and detected the presence of minute amounts of parabens in the tissue. Since parabens are known to be weak estrogen mimics, the paper suggested a connection between the presence of parabens in breast tissue and breast cancer.

Then in September, Japanese researchers presented a paper at a conference of the International Federation of Societies of Cosmetic Chemists in Florence, Italy, that added to concerns over parabens. The researchers, mostly from the Kyoto Prefectural University of Medicine, applied lotion containing just one type of paraben—methylparaben—twice a day for a month to the skin of 12 Japanese volunteers. They found that methylparaben did not metabolize in the strateum corneum, the outermost layer of the epidermis, and suggested that its presence accelerated skin aging.

Critics point out that it is difficult to reach any broad conclusions about parabens based on the small number of samples in the two studies. For this reason, a number of large cosmetics makers, such as Avon and Este Lauder, have hesitated to make changes in their formulations and have assumed a wait-and-see attitude.

At least one activist group, however, says it has heard all it needs to hear and has mobilized against firms that formulate cosmetics with parabens. A San Francisco-based group called Breast Cancer Action has encouraged consumers not to use products from Avon and Este Lauder because many of them incorporate parabens. Breast Cancer Action, along with Domini Social Investments, which describes itself as a socially responsible investment firm, forced a vote at Avon's annual meeting in May 2003 on a resolution that would have required Avon to seek safer alternatives to parabens. The group was concerned about parabens even before the two studies were reported.

Avon management opposed the shareholder resolution and argued that there are many published studies conducted by both independent scientists and agencies on parabens, some of which specifically address the issue of carcinogenicity. We believe that these studies do not support the proponents' assertion that there is substantial scientific evidence linking exposure to parabens with increased health risk.

The resolution did not pass. But Breast Cancer Action continues to put pressure on cosmetics makers to reformulate. The group recommends that people use cosmetics that do not contain parabens and that they patronize cosmetics firms that formulate without an ingredient that at one time seemed nearly ubiquitous. In fact, some products now on the market boast they are paraben free.

The cosmetics ingredient supplier International Specialty Products has been closely following the controversy over the use of parabens, according to Patrick Bowers, corporate development director. Some of our customers are concerned, and some are not, he says.

“Parabens are economical, broad-spectrum preservatives. They are the most widely used preservatives worldwide.”

For decades, ISP has been selling preservatives such as Germaben II, a blend of methylparaben and propylparaben with diazolidinyl urea in a propylene glycol base. The formula is active over a wide pH range. Other paraben-containing preservatives include ISP's LiquaPar paraben oils.

Safety is always paramount, Bowers says. But different customers have different needs. In our industry, perception often trumps science. So to address customer concerns, ISP has alternatives to traditional preservatives available.

For instance, the firm's Optiphen preservative contains phenoxyethanol in an emollient base of caprylyl glycol. Optiphen Plus adds sorbic acid to the base formulation. Optiphen is best in formulations in a pH range of 6 and above, while Optiphen Plus is targeted at products with a pH of 6 and below. We focus on systems and blends tailored to our customers' needs, Bowers points out.

Parabens are economical, broad-spectrum preservatives, asserts Reith Karl, international manager for Germany-based preservatives specialist Schlke & Mayr. They are the most widely used preservatives worldwide, he says, and have until recently been considered safe. It is no surprise that parabens would have been found in breast tissue, he adds, since parabens are approved for use in pharmaceutical creams.

While Schlke & Mayr's product line includes a range of parabens, it also includes alternatives. For instance, Euxyl PE 9010 contains phenoxyethanol and ethylhexylglycerin. The second ingredient is used for better wetting action on the microbes and so kills them more effectively, Karl says.

Though some ingredient suppliers are offering alternatives to parabens, Rohm and Haas has moved against the trend. It introduced the Neolone line of methylisothiazolinone-based preservatives and included one containing parabens. Neolone MxP, launched a year ago, is a blend of methylisothiazolinone, phenoxyethanol, methylparaben, and propylparaben. It is cost-effective, Business Manager Dianne Carmody says. It remains in Rohm and Haas's line because, while some customers may be avoiding parabens, some are not, she says.

Mark Chandler, technical manager for Uniqema Personal Care, a unit of specialty chemical firm ICI, says, As far as we know, there is no technical argument against the use of parabens in cosmetic formulations. The few studies that question the use of parabens do not definitively point to any problems with this traditional preservative.

But where formulators feel the pressure to remove or minimize the use of traditional preservatives, Uniqema says it can help. The firm does not make preservatives, but it has recently developed a coconut-derived phospholipid, Arlasilk Phospholipid PTM, that it says dramatically cuts down on the use of preservatives.

Each cosmetics product is different, Chandler says, and requires a customized approach. Arlasilk Phospholipid PTM has cleansing, emulsifying, and conditioning properties. In carefully formulated hair and skin care products, it can be utilized to minimize preservative requirements and to develop self-preserved systems, he adds.

Mike Curtis, commercial development manager for Mason Chemical, says the consumer backlash over parabens provides a lesson on how the personal care market works. When consumers look askance at an ingredient, it is not always science that drives cosmetic reformulation. As a result, enhancing a formulation so that it doesn't need preservatives seems to really resonate with personal care product formulators.

But scientists have come up with alternatives to traditional preservatives, which, in addition to parabens, include isothiazolinone and formaldehyde donors such as imidazolidinyl urea. Some studies have cast suspicion on isothiazolinone as a skin sensitizer and possible mutagenic compound. Formaldehyde donors are also thought to cause skin reactions in sensitive individuals.

At Mason, scientists combine conditioning, moisturizing, thickening, and pH-control ingredients under the Enhansys brand to make possible self-preserving cosmetics that do not require traditional preservatives. For instance, Enhansys C-110 is a blend of the exfoliant gluconic acid, the moisturizer glucono delta lactone, and the stabilizer and conditioning agent C418 perfluoroalkylethyl thiohydroxypropyltrimoniun chloride.

Many cosmetics formulators now have programs to review and remove parabens when they can, says Jim Plaza, vice president of technology and innovation for Body Blue, a Canadian contract manufacturer of cosmetics. The firm first developed a paraben-free deodorant stick using a natural blend of ingredients. In doing so, Plaza says, it stumbled on a system of all-natural ingredients that is self-preserving.

By themselves, the materials have no discernible activity, Plaza says. But when these ingredients are coupled, they develop unexpected synergies. Body Blue has patented the blend and will eventually promote it under the Naturbak name. While he won't divulge the ingredients, Plaza says the firm has been working on Naturbak for three years. Major players have tested and validated our findings on the odorless and colorless ingredient system, he says.

Ever since the Journal of Applied Toxicology article came out, the effort to replace parabens and other traditional preservatives got legs because of consumer perception, says Stephen D. Hinden, commercial development director for Arch Personal Care Products. Arch has developed three new preservatives. The first, Mikrokill PCC, is a blend of phenoxyethanol, chloroxylenol, and caprylyl glycol. It is compatible with a range of skin care, hair care, and sunscreen formulations at use levels of 0.5–1%.

Another preservative, Cosmocil CQ, is based on polyaminopropyl biguanide. Approved for use in the U.S., Europe, and now in Japan, this bactericide originally replaced thimerosal in contact lens solutions and came to Arch when the firm bought Avecia's biocide business last year.

The third new preservative, Biovert, mimics a natural enzyme system that keeps bacteria at bay in saliva, tears, and breast milk. Biovert consists of glucose, glucose oxidase, and lacto peroxidase. Activated in the presence of oxygen, a biological cascade leads to an attack on fungi and bacteria, Hinden says.

Formulators don't want to lose parabens, but they are under pressure to change because of public perception, says Carl Cappabianca, personal care global marketing vice president at Lonza. Alternatives, he says, include the firm's Geogard Ultra, which is specifically meant to address concerns over traditional preservatives. Targeted for leave-on products, Geogard Ultra combines a glucose-derived lactone potentiator that works synergistically with sodium benzoate. The glucose-derived lactone provides an added benefit: It is a skin moisturizer, too.

Despite the large number of alternatives available, parabens are not about to disappear. It will take larger studies and government action to really force formulators to find alternatives, and so far that doesn't appear to be happening. While parabens are no longer above suspicion, most formu-la-tors are not ready to uniformly replace them.