The search is on for new cosmetic preservatives

In May, Bocchi Laboratories recalled its Medline Remedy Essentials No-Rinse Cleansing Foam, used to wash hospital patients. Burkholderia cepacia, a Gram-negative bacteria complex that can lead to serious respiratory infections in immune-compromised individuals, had contaminated the preparation. The U.S. Food & Drug Administration warned of a possible life-threatening infection, and the Centers for Disease Control & Prevention confirmed 15 illnesses in hospitalized patients.

FDA’s cosmetic recall database lists a half-dozen other cases of contaminated cosmetics since June. The recalls involved batches of baby wash, body care products, and tattoo inks with high levels of potentially harmful microbial organisms. Among the contaminants were infection-causing Enterobacter aerogenes and Pseudomonas aeruginosa.

FDA doesn’t disclose the reasons for the contamination, but faulty preservatives could be involved. Without preservatives, many personal care products would be hospitable breeding grounds for bacteria, fungi, and mold. At a minimum, these bad actors can make shampoos and skin creams look unappealing and smell bad. More seriously, they can cause eye, skin, and respiratory infections.

However, many of the preservatives that prevent the growth of harmful microorganisms in personal care products are themselves accused of irritating skin, causing allergic reactions, and disrupting the human endocrine system. Last year, European authorities banned the use of methylisothiazolinone in cosmetics, such as lotions that remain on the skin, because the ingredient can be irritating.

European regulators also put restrictions on paraben preservatives such as propylparaben, fearing they might be endocrine disruptors. Though the government-sanctioned body reviewing parabens did not come to a definitive conclusion on their endocrine disruption potential, it agreed to cut back how much formulators could use in a product.

Separately, environmental groups are lobbying against formaldehyde-releasing agents, such as DMDM hydantoin, because they might evoke an allergic response.

Large personal care product makers take the criticisms seriously. In recent years, for example, Johnson & Johnson has removed formaldehyde donors and parabens from its baby products. Yet a J&J advertorial in the Sept. 9 issue of the New York Times Magazine points out that personal care preservatives are not necessarily harmful and that synthetic chemicals are not automatically inferior to natural ingredients.

Caught in a similar bind, traditional preservative suppliers such as Lonza and Clariant are turning to food preservatives and to naturally derived synergists to make a little bit of a preservative go a long way. They are also pursuing new technology and seeking out academic and government experts who can help them find biobased alternatives to dependable, low-cost synthetic preservatives. But making the change isn’t easy.

Some food preservatives have always found use in personal care products, but the current brouhaha means makers of food preservatives are experiencing an uptick in demand. Edward Gotch, CEO of Emerald Kalama Chemical, a maker of benzoates—including benzoic acid, sodium benzoate, and benzyl alcohol—says the number of personal care products launched containing benzoates is rising 7% annually. Benzoates have been used safely for years in foods and beverages, he points out.

They are a readily available alternative to those biocides now under fire, Gotch says. Benzoic acid produced via toluene oxidation is no different than the benzoic acid found in cranberries, he notes. What’s more, certification agencies such as Ecocert accept benzoic acid in products labeled organic, he says. The firm recently completed an expansion of benzoic acid capacity in Rotterdam, the Netherlands, and it plans to add more sodium benzoate capacity at the site within the next two years.

Another food preservative, cetylpyridinium chloride (CPC), is also expanding its presence in personal care. CPC “has been a trusted ingredient for over 50 years,” says Jessica Byrd, a marketing manager for CPC maker Vertellus. CPC prevents bacteria growth in meat and poultry processing plants, she says. In addition, many mouthwash makers use CPC as their active ingredient.

CPC still awaits a listing on Annex V, the European list of approved cosmetic preservatives. The ingredient is effective against most microbial contaminants, with the exception of some types of Aspergillus fungi in some types of cosmetic formulations, Byrd says. For those formulations, Vertellus offers a blend of CPC with benzoic acid to give broad-spectrum coverage.

Nicolas Lasbistes, a personal care technical marketing manager for Clariant, calls the growing use of food preservatives in cosmetics the “skin-food trend.” The idea is that “if it’s good to eat, it should be good for my skin,” he says. That way of thinking cuts across cultural differences and is attractive to consumers across the globe, he notes.

That wide appeal is partly the reason Clariant incorporates food preservatives into its Nipaguard range of preservatives intended to replace parabens. Benzoic acid and benzyl alcohol are among the ingredients used. The line also includes potassium sorbate, a food preservative widely used to inhibit mold and yeast in foods such as cheese, yogurt, and apple cider.

Key to the effectiveness of the Nipaguard line, Lasbistes says, is the inclusion of the preservative booster sorbitan caprylate, which is made by reacting sorbitan from wheat or corn with caprylic acid derived from palm or coconut oil. Sorbitan caprylate acts like a surfactant to crack open bacteria and cell membranes. The preservatives can then penetrate the microorganisms and kill them.

Other preservative suppliers are also using boosters to enhance the effectiveness of both traditional and newer preservatives. Phil Hindley, marketing head for preservation at Lonza, says his firm is working with booster technology to keep an effective traditional preservative, phenoxyethanol, in the formulator’s toolbox. Critics now attack phenoxyethanol, which has been in use since the 1950s, as a skin irritant.

Even though European authorities reviewed phenoxyethanol two years ago and reaffirmed that cosmetic formulators can safely use it at 1% concentration, Hindley thinks questions raised by critics about the preservative have damaged its long-term prospects. One way to allay consumer and regulatory concerns, he says, is to add a booster that allows phenoxyethanol to work effectively at concentrations below 1%.

Lonza offers a blend of phenoxyethanol and chlorphenesin with the booster caprylyl glycol. But formulating some of the new blends can be tricky. Traditional preservatives such as parabens “were built as biocides and had minimal impact on formulation properties,” Hindley says.

Cosmetic makers typically need to add a higher percentage of the alternative blends to do the work of a traditional preservative. The larger preservative load can affect cosmetic properties such as skin feel. “As we move away from the era of traditional chemical preservatives, the art of preservation can no longer be an afterthought,” Hindley says.

As formulators make the move, they should think long and hard about the alternatives, says Nava Dayan, a skin research consultant to personal care and pharmaceutical firms. “You can’t just assume that if you can safely swallow a preservative it will also be safe on your skin,” she says.

A person’s gastrointestinal system is well equipped to break down chemicals in food that the liver then neutralizes, Dayan explains. “This doesn’t happen when you apply preservative-containing cosmetics on your skin,” she says.

And Dayan says she can understand why some people may be concerned about traditional preservatives as well. “We are limited in our ability to understand long-term cumulative exposure to preservatives,” she says. “Are they absorbed in the blood? Are they metabolized or excreted? Or do they accumulate in the body, and could they be harmful, and to what extent?”

Questions like these apply to new preservatives under development too. A competition under the aegis of the Green Chemistry & Commerce Council (GC3) turned up a few new preservative options this summer. Consumer product companies, major retailers, and preservative makers including Lonza and Dow Chemical backed the challenge, in which winners shared $175,000 in prize money.

Among the winners was the Safer Preservation Project, led by the U.S. Department of Agriculture. Project members William Hart-Cooper, a USDA research chemist; Heather Buckley, a University of Victoria assistant professor; Kaj Johnson, a product development director at cleaning products maker Method, and others developed what Hart-Cooper calls a nonirritating, low eco-toxic, broad-spectrum preservative made from two nontoxic components. When diluted in water treatment plants, the preservative molecule dissociates into benign biodegradable components, he says.

Because USDA hasn’t received a patent yet, Hart-Cooper won’t reveal details, other than to say that the ingredients are mostly from common agricultural products.

But formulators will want to know a whole lot more about the new preservatives before they consider putting them into a product. When they use a preservative, formulators are essentially investing in an insurance policy, Dayan says.

Their goal is to protect cosmetic formulas from contamination and shield users from harm. “So they must do a thorough assessment of the preservatives they use,” Dayan says, to be sure they choose the right insurance vehicle.