In 2016, the FDA banned triclosan from consumer antiseptic wash products after years of research on thyroid disruption and antibiotic resistance. But triclosan was one compound in a larger class. Phenols remain in disinfectants, mouthwash, and other product categories the ban did not cover. As part of the No Nines™ Standard™, we exclude the entire phenol class from every product we make. This post explains what phenols are, what the research says about them, and why the FDA ban, while meaningful, only addressed part of the problem.
What are phenols?
Phenols are a class of organic compounds built on the same basic structure: a hydroxyl group (an oxygen-hydrogen pair) bonded to an aromatic ring (a six-carbon ring with alternating double bonds). That structure is the backbone. What varies from one phenol to another are the atoms and groups attached around the ring, and those variations determine the compound's specific properties, from antimicrobial strength to toxicity.
The phenol family includes a wide range of compounds used across household and industrial products. Triclosan and triclocarban were the most prominent antimicrobial phenols in consumer hand soaps before the 2016 ban. Chlorophenols, including 2,4,6-trichlorophenol, are used as preservatives and intermediates in pesticide manufacturing. Cresols (methylphenols) appear in pine-oil based cleaners and disinfectants. Phenol itself, the simplest compound in the class, is used in some disinfectant sprays and industrial cleaners.
If you have used a pine-scented cleaning product, a disinfectant spray, or certain mouthwashes, you have likely encountered a phenol-based ingredient. Many of these products do not list the word "phenol" on the label. Instead, you will see chemical names like chloroxylenol, o-phenylphenol, or thymol, all members of the same family.
The partial ban
On September 6, 2016, the FDA published a final rule establishing that 19 active ingredients, including triclosan and triclocarban, are not generally recognized as safe and effective (GRAS/GRAE) for use in consumer antiseptic wash products. The rule, which took effect in September 2017, applied to liquid hand soaps, bar soaps, and body washes marketed with antibacterial claims.
The scope of that ban was narrow. It covered consumer wash products that are used with water and rinsed off. It did not cover hand sanitizers, antibacterial wipes, or antiseptic products used in healthcare settings such as hospitals and surgical suites. It did not cover cleaning products, which fall under EPA jurisdiction rather than FDA regulation. And it did not cover toothpaste. Colgate Total remained the only triclosan-containing toothpaste on the U.S. market until the company voluntarily reformulated in January 2019, replacing triclosan with stannous fluoride.
Three ingredients from the original proposed rule, including chloroxylenol, were deferred to allow manufacturers additional time to submit safety data. The FDA's reasoning for the ban was not that triclosan had been proven dangerous in a definitive trial. It was that manufacturers had failed to demonstrate that these antibacterial ingredients were both safe for long-term daily use and more effective than plain soap and water. The burden of proof was on the manufacturers, and they did not meet it.
Meanwhile, phenol-class compounds continue to be used in disinfectant sprays, surface cleaners, toilet bowl cleaners, and other EPA-regulated products with no equivalent review process.
What the research says
The research concerns around phenols cluster into four areas: endocrine disruption, antibiotic resistance, carcinogenicity, and environmental persistence. Not every phenol compound raises every concern, but the class as a whole carries enough documented risk to warrant a precautionary approach.
Thyroid disruption. Triclosan's molecular structure is similar to thyroid hormones T3 and T4. That structural resemblance allows it to interact with thyroid hormone receptors and interfere with thyroid hormone metabolism. A 2022 systematic review published in Frontiers in Endocrinology found that most rodent studies showed triclosan exposure decreased serum levels of both T3 and T4 at doses ranging from 1 to 300 mg/kg/day. The EPA has identified triclosan as a potential endocrine disruptor, citing evidence of alterations in thyroid hormone homeostasis. Human studies remain limited due to ethical constraints on dosing, but the animal evidence is consistent and well-replicated.
Antibiotic resistance. Triclosan works by inhibiting enoyl-acyl carrier protein reductase (ENR), an enzyme bacteria need for fatty acid synthesis. This is the same enzyme targeted by isoniazid, a critical antibiotic used to treat tuberculosis. Research published in Biochemistry (2000) demonstrated that mutations conferring triclosan resistance in Mycobacterium smegmatis also conferred resistance to isoniazid. This cross-resistance is not theoretical; it has been observed in laboratory isolates. A 2001 study in Antimicrobial Agents and Chemotherapy showed that triclosan exposure in Pseudomonas aeruginosa selected for mutants overexpressing efflux pumps, the same resistance mechanism used against clinical antibiotics.
The FDA concluded that manufacturers failed to demonstrate antibacterial soap ingredients are more effective than plain soap and water at preventing illness. "Consumers may think antibacterial washes are more effective at preventing the spread of germs, but we have no scientific evidence that they are any better than plain soap and water," stated Dr. Janet Woodcock, then director of the FDA's Center for Drug Evaluation and Research.
Carcinogenicity. The EPA classifies 2,4,6-trichlorophenol as a Group B2 probable human carcinogen, based on studies showing increased incidence of lymphomas, leukemias, and liver tumors in rats and mice exposed orally. Other chlorophenols have been classified by the International Agency for Research on Cancer (IARC) as Group 2B possible human carcinogens. These are not obscure industrial chemicals; chlorophenols are used as wood preservatives, in pesticide production, and as intermediates in manufacturing processes that affect household products.
Environmental persistence. A landmark 2002 USGS study led by Dana Kolpin sampled 139 streams across 30 U.S. states and detected triclosan in 57.6% of them. That study, published in Environmental Science & Technology, became one of the most cited papers in the journal's history. Triclosan enters waterways primarily through wastewater discharge and sewage sludge. Once in the environment, it persists, accumulates in aquatic organisms, and can form dioxins when exposed to sunlight, compounds with their own well-documented toxicity profile.
What No Nines uses instead
The No Nines approach to phenol-class compounds is straightforward: we exclude them entirely. No triclosan, no chlorophenols, no cresols, no phenol. This applies across every product in the line, from surface cleaners to personal care.
For surface cleaning and disinfection, we use hypochlorous acid (HOCl). HOCl is a naturally occurring molecule produced by white blood cells as part of the human immune response. It is a strong oxidizer that works against bacteria, viruses, and fungi without the endocrine disruption, antibiotic resistance, or environmental persistence concerns associated with phenol-class antimicrobials. Our Whole Home HOCl Cleaner is built on this chemistry.
For hand washing, the answer is even simpler. Our Foaming Hand Wash uses plant-based surfactants to clean effectively. The FDA's own position supports this approach: plain soap and water is as effective as antibacterial soap at preventing illness and the spread of infection. The antimicrobial ingredients in antibacterial soaps did not demonstrate any added benefit, but they did carry added risk. Removing them is not a compromise. It is alignment with what the evidence actually supports.
The bottom line
The 2016 FDA ban was a meaningful step. It acknowledged that a class of widely used antimicrobial ingredients had not been proven safe for daily long-term use and had not been shown to outperform plain soap and water. But the ban was limited in scope. It covered hand soaps and body washes. It did not cover cleaning products, healthcare antiseptics, hand sanitizers, or the many other phenol-class compounds still in use across consumer products.
No Nines does not wait for regulatory action to catch up to the research. The No Nines Standard excludes the entire phenol class, not because every compound in the class has been individually banned, but because the body of evidence on the class as a whole points in a clear direction. When effective alternatives exist that do not carry the same documented risks, the formulation decision is straightforward.
This is the fourth in our Nasty Nine series. You can read more about quaternary ammonium compounds (Post 1) or continue to bleach and sodium hypochlorite (Post 6). To see all nine categories we exclude, visit The No Nines Standard.
