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The Product Claim Game

Navigating the world of disinfectants, one bottle at a time

by Nancy Lawson

The microbial monsters have invaded. You can’t see them or hear them multiplying themselves into infinity, but you can sense them in the presence of the little sneezes starting in the cat room and the diarrhea showing up in the kennels. If your eyes possessed the power of an electron microscope, you might even be able to spy them flying out of the noses and mouths and other excreting extremities of your furry charges.

Just the idea of it is enough to make you want to turn to the bottle—the disinfectant bottle, that is.

But which one should you choose? Which one will be safe for you, your animals, and your equipment, while still remaining effective enough to stave off the army of bugs? After you’ve already mapped out consistent standard operating procedures that include important disease control measures—isolation of sick animals, separation of healthy ones, proper ventilation, and the like—you’ve still got another maze of questions to navigate.

Before actually attempting to select a product, however, it helps to know how a “disinfectant” officially earns its name in the first place. The Environmental Protection Agency categorizes disinfectants as pesticides that destroy or inactivate infectious fungi and bacteria; many disinfectants also kill viruses, but claims of virucidal activity “must be restricted to those viruses which have actually been tested,” according to agency regulations. The EPA scrutinizes test results and other information to ensure labeling accuracy, weed out misleading statements, and clarify instructions for use; agency regulations dictate everything from minimum application times on surfaces to acceptable artwork on the bottle label. (See Defining the Terms for additional clarification on some common terms you may encounter while developing a cleaning and disease control program for your facility.)


Other government agencies have a hand in the registration, labeling, and production process of chemical cleaning solutions. Liquid chemical sterilants, which kill all microscopic life forms except prions (the infectious proteins responsible for mad cow disease), are used in food production facilities and on medical equipment—and are therefore under the purview of the Food and Drug Administration. The FDA also governs registration and approval of germicidal products that are used directly on animals for pest-control purposes. And to make matters even more confusing, even though the EPA registers hard-surface disinfectants, a third agency, the Occupational Health and Safety Administration, oversees the “materials safety data sheets” that advise product users of the hazards of certain chemicals and the precautions they should take.

It’s a jungle out there,with enough acronyms and regulations and claims to make your head spin. But it’s worth the trouble to try to sort through some of it; learning a little bit about how a product gets to the market will help you research whether you actually want to buy it.

Oh Where, Oh Where Did My Parvo Claim Go?

Besides, the maze is considerably more manageable when you realize that for the purposes of cleaning the shelter, products registered with the EPA are the only ones you need to concern yourself with. EPA-registered disinfectants include some kinds of bleach, quaternary ammonium compounds, and many things in between. And even if the manufacturer doesn’t post enough information about its product on the Web or elsewhere for public consumption, chances are you’ll be able to use EPA search engines to find labeling information and other documents before making a purchase. (See “Great Points in the Fine Print” for more information.)

Undoubtedly, your most pressing question about a product will be: What does it kill? Shelters and other animal protection organizations have long used quaternary ammonium compounds and bleach—and those are still mainstays of the animal care environment. It’s true that bleach is unstable and corrosive, and quats, as they are commonly called, are limited in their efficacy against the most resistant viruses. But most of the other available chemicals are not effective enough or simply too unsafe; products containing phenols, a synthetic chemical once derived from coal tar and now found in some Lysol disinfectants and other solutions, can be fatal to cats who ingest even a small amount.

Steer Clear of Phenols

Disinfectants containing phenols are extremely toxic to some animals, including cats and reptiles. First isolated from coal tar in the 1800s, phenols are now manufactured synthetically and are included in many products, including some Lysol disinfectants. Colorless to white when pure, phenol has a strong, sweet odor. It is corrosive and requires extra precautions when handling.

To ensure the disinfectants you’re considering purchasing don’t contain phenols, check with manufacturers and avoid products that list any of the following ingredients, which are synonyms for “phenol,” according to the Occupational Health and Safety Adminstration: carbolic acid; monohydroxybenzene; hydroxybenzene; benzenol; phenylic acid; phenyl hydroxide; benzophenol; phenyl hydrate; phenylic alcohol; monophenol;phenic acid; and oxybenzene. To learn more about the hazards of phenol, visit the OSHA website.

In the search for an ideal solution—chemical and otherwise—to disease control, many people over the last 15 years have latched onto products claiming parvocidal qualities. Introduced in the late ’80s, these disinfectants were hailed as the next great thing in shelter disinfection; the canine parvovirus had already shown an amazing ability to devastate kennel populations. Its virulence was something to be feared, and resistance often seemed futile. Disinfectant sellers who promised to change all that were, of course, a source of great hope.

But a few years later, the Journal of the American Animal Hospital Association (JAAHA)published a study countering some of the virucidal claims of quats. In “Virucidal Efficacy of the Newer Quaternary Ammonium Compounds” (May/June 1995, Vol. 31), researchers at the University of Tennessee’s College of Veterinary Medicine tested several products and found that only two out of four quats completely inactivated feline herpesvirus, none completely inactivated feline calicivirus, and none even significantly inactivated canine parvovirus.

By 1997, parvocidal claims began to disappear from bottle labels, leaving a trail of confusion in their wake: while some companies were quick to react to the mounting body of literature questioning the efficacy of quats against parvoviruses, others were slower to back away from old promises. If you ask ten different people exactly what unfolded during that period, you get ten different answers, but essentially what happened is this: Huntington Laboratories, at the time one of several quaternary ammonium makers, began to question whether it was wise to continue trying to substantiate its claims in light of new evidence that contradicted them. New practices were being introduced in EPA-approved testing laboratories around the country, and old testing standards had come under scrutiny industrywide.

At the same time, the EPA was undergoing a “reregistration process” of antimicrobial products that required manufacturers to submit new data, says Ruth Trager, manager of marketing and product development for Lonza Inc., the company that bought Huntington Labs in 1996. Retesting previously approved products to substantiate old claims would be expensive—prohibitively so for a product that was likely to fail the newer tests anyway. Even though the EPA hadn’t even come near the quats yet (and still hasn’t 15 years later, according to Trager), companies began anticipating the implications of reregistration and reconsidering their options.

And in the face of the new data, it probably wasn’t worth the effort and expense to try to justify parvocidal claims that had already been disproven; thus, Huntington voluntarily pulled the parvovirus claim from its product. The move launched a domino effect among “subregistrants”—companies that had been selling the Huntington formula under their own brand names.

“Basically, all these companies, including us, in 1989 had put our name on a quat formulation that had a parvo claim,” says Chris Quinlan of Animal Health Technology in Riverside, California. “So I used to go to the trade shows and say, ‘Why do you pay so much for Parvosol? My product’s the same thing.’ And I could show them on the label that it was the exact same active ingredient.”

But soon enough, Quinlan lost that selling point, when he and other subregistrants received letters from Huntington telling them to remove the claim from their bottles. The companies were forced to comply; by law, their labels had to be identical to that of the master registrant.

But if distributors like Quinlan were disappointed by the loss of the parvo claim, shelters were probably even more so, especially since that wasn't the end of the story. Parvocidal claims were disappearing only selectively; other companies that did not subregister but instead made their own formulas—or used those of other quat manufacturers—did not have to remove the claim.

And therein lay the confusion, with some quats claiming parvocidal qualities and others suddenly backing away from the subject altogether.

The Virus That Won’t Die?

Unraveling the mystery and history of parvocidal claims—and exploring their current status—is easier if you understand why such emphasis is placed on the ability to deactivate parvovirus in the first place. In a nutshell, parvovirus is likea nutshell: difficult to crack with common disinfectants.

All viruses consist of a piece of nucleic acid, or genetic material, usually surrounded by a protein coat. But some, such as canine distemper, have yet another layer—a fatty “envelope” that makes them more vulnerable to common disinfectants, says virologist Leon Potgieter, a professor at the University of Tennessee who co-authored the 1995 JAAHAstudy of quats and has conducted other research on disinfectants.

Once that layer breaks down in the face of chemicals, the virus’s genetic material might still be intact, but it has lost its ability to do damage, says Potgieter. That’s because the fatty layer houses the mechanisms that allow the virus to attach itself to a host cell and wreak havoc. Without that layer, the virus can no longer replicate.

Attachment mechanisms for parvovirus and calicivirus, on the other hand, are contained inside the protein coat, which is much more resistant to disinfectants. These are “nonenveloped” viruses that can stand their ground in the presence of typical quaternary ammonium compounds diluted at the usual two-ounce-per-gallon rate.

“In our results—we’ve [tested] this several times—there is no single quaternary ammonium compound that does much against parvoviruses or caliciviruses, both quite resistant viruses,” says Potgieter, whose need to completely disinfect in the lab is critical to the integrity of his experiments. “So we stayed with bleach.”

A study led by one of Potgieter’s graduate students and published last year in JAAHAcompared several different disinfectants and found again that the quaternary ammonium compound was not effective against feline calicivirus or feline panleukopenia, a kind of parvovirus (“Virucidal Efficacy of Four New Disinfectants,” May/June 2002,Vol. 38). Sodium hypochlorite, or bleach, served as a control and killed all the viruses tested, including calicivirus, panleukopenia, and feline herpesvirus. Chlorine dioxide, a difficult-to-mix chemical that’s not recommended for the shelter environment, and potassium peroxymonosulfate, a potentially promising new import used during England’s foot-and-mouth disease epidemic, completely inactivated all three viruses.

But if quats don’t kill parvo at 2 ounces per gallon, how did the parvocidal claims ever come about in the first place? Potgieter suspects they were the result of testing that didn’t adequately mimic a real-life situation. “To be able to grow parvovirus, you need very healthy cells,” he says. “And if you don’t get rid of all the disinfectant in your test material, the cells are not growing very well, and the virus won’t grow either. So I’m sure that’s what happened.”

A chapter of the reference manual Kirk’s Current Veterinary Therapythat describes testing methods reaches a similar conclusion (“Disinfection and Antiseptic Use in Small Animal Practice,” Volume XIII): “There are many variables that may affect the test outcome, including the test organism used, the method of preparation of the organism, and the subculture method used,” wrote Brenda C. Love and Dwight C.Hirsh. “Test organisms may undergo spontaneous inactivation on certain carriers, making the disinfectant appear more effective than it is.”

Where Does That Leave Us?

But there is hope for the parvocidal abilities of quats, which have long been used because they are relatively safe for animals and staff and because, in spite of their inability to kill the strongest microorganisms at low dilution rates, they carry broad-spectrum effectiveness against many likely contaminants.

In fact, ready-to-use sprays carry EPA-registered parvocidal claims, though their high levels of active ingredient make them more expensive to use than products that are dilutable with water. But in recent years, manufacturers have begun retesting those dilutable solutions and have discovered that just increasing the amounts poured into a bucket of water makes all the difference. “We found that, historically, quats have not been effective against parvovirus in the published literature,” says Trager. “But at high enough levels, [they are].”

The idea makes sense; after all, as an article in the April 2001 issue of Infection Control Todaynoted, “The more concentrated the germicide, the greater its killing capacity.” The higher concentration levels sometimes introduce a new set of problems, the article notes—namely, increased safety risks and a greater likelihood that surfaces will be damaged by repeated exposure to the disinfectant.

But Trager dismisses those concerns, noting that the quat Lonza is planning to sell at a higher ounce-per-gallon ratio is strong enough to kill parvo but not even as concentrated as the ready-to-use sprays that are already on the market. Lonza’s dilutable parvo-killer is pending approval at the EPA, she says.

Animal Health Technology is already selling a similar product, Kennel Kare—and has been for several years. To kill parvo, users must dilute it at 18 ounces per gallon; the higher dilution rate ensures there is more active ingredient in the mixture, says Quinlan.

There is a drawback, he adds. The less you dilute a product, the more you’re paying per gallon, and Kennel Kare runs about $1.70 per gallon when diluted—considerably more than Animal Health Technology’s less concentrated product, Triple Two, which uses only two ounces per gallon and costs about 20 cents a gallon when diluted.

Ready-to-use products are even more expensive—often prohibitively so for some shelters. Depending on the company you buy it from, a ready-to-use spray can cost between $350 and $500 for a 55-gallon drum, or $6 to $9 a gallon, says Lori Todd, kennel supervisor of the Charlotte-Mecklenburg Animal Control Bureau in North Carolina. But given the options, some facilities would rather pay the price than use bleach routinely. “It has been an acceptable expense,” says Todd, whose staff uses ready-to-use TB-Cide Quat in spray bottles for cleaning cat cages. “I prefer it over the bleach because I have asthma. ... The bleach irritates my lungs, so I knew it was going to irritate [the cats’ and the staff’s] lungs.”

Exploring the Unknown

The bright side of bleach, of course, is that it irritates the microorganisms far more than it irritates the macro ones, killing even the most resistant viruses (see “The Bleach Niche”). But the corrosive, staining, and irritating qualities of sodium hypochlorite have had many people searching for years for an alternative.

And the staff at Pharmacal Research Laboratories, a Connecticut-based company, think they’ve found one in England. As another former subregistrant of Huntington, Pharmacal was disappointed when it could no longer offer a dilutable parvocidal quat. But the company recently began importing Virkon S, a disinfectant made of potassium peroxymonosulfate, because of its parvocidal claims and safety assurances. According to company literature, the chemical is not as caustic as bleach, doesn’t stain clothing, and does its disinfecting job even in the presence of feces and other organic matter.

Used by a few shelters, the product has become increasingly popular in veterinary schools, says Potgieter, whose test results confirmed the chemical’s effectiveness against parvovirus and calicivirus (JAAHA, May/June 2002). In fact, Potgieter is considering converting to Virkon S in his own laboratory.

Like the high-concentrate quats, however,Virkon S also comes at a bit of a price: Buying it in ready-to-use packets of powder that can be dumped into a gallon of water will cost you $1.95 a pop. Buying it in 10-pound pails makes it much cheaper—about 40 or 50 cents a gallon, says Pharmacal Quality Assurance Lab manager Tammy Marotta Fleischer.

While she hasn’t tested it out herself yet, veterinarian Kate Hurley is intrigued by the fact that Virkon S has been shown by company testing to inactivate bacteria and viruses on wood and other difficult surfaces. “Bleach is the thing that kills everything reliably, but it does not work on something wood, on cracked concrete, on gravel, or in any of those circumstances where you really might need to disinfect—you [could] just spray bleach all day long, but it’s not going to do a bit of good,” says Hurley, who is director of the Maddie’s Shelter Medicine Program at the University of California, Davis, School of Veterinary Medicine.

In those circumstances, if it’s not possible yet to take the ideal course of action and eliminate wooden surfaces, it might be prudent to try scrubbing and then disinfecting with Virkon S, says Hurley.

But, she adds, “Shelters [should] keep in mind to have disinfectable surfaces because, for surfaces that you can’t spray bleach on, ultimately, there’s just really no other good answer for decontaminating them with one of these really durable [pathogenic] agents.”

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