Triclosan: A Controversial Chemical in Your Soap

Triclosan: A Controversial Chemical in Your Soap

By Connie Tang, Member-at-Large for the GCI

Triclosan: it’s in your soap, body wash, and your toothpaste. It can be even found in yoga mats.

Triclosan is an antibacterial agent added to household products. While soap is rarely the centre of a news story, triclosan has garnered significant controversy after the United States Food and Drug Administration (FDA) banned these potentially hazardous chemicals (along with 18 others) from hand soaps.1 Meanwhile, Canada has labelled the chemical as toxic for the environment, and maintained that it does not meet the standard for human health toxicity.2

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What is triclosan and where is it beneficially used?

Antibacterial soaps (also known as antimicrobial or antiseptic soaps) contain additional chemicals with the intent of reducing bacterial infection. Triclosan is one of these chemicals and is often used in personal care products, cosmetics, and can even be found in toys, kitchenware, and furniture. In the past two decades, its use has expanded commercially and by the year 2000, triclosan was found in 75% of liquid soaps and almost 30% of bar soaps.3

Antibacterial agents, like triclosan, were originally used in surgical scrubs and hand washes to protect health workers in medical settings from bacteria that can cause infections in hospitals. In surgical units, triclosan is effective against bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to most antibiotics.

Additionally, triclosan can be found in toothpastes, because it has been linked to improved protection against cavities.

In 2008, the Environmental Working Group (EWG) found high levels of triclosan in San Francisco Bay, which prompted studies of this chemical in blood and urine samples of teenage girls to explore its impact on endocrine hormonal processes. Since 2008, the EWG has been submitting reports to the FDA to ban triclosan in personal care products.8

Is triclosan dangerous?

Short answer: Triclosan is most likely harmful to the environment, and possibly harmful to humans.

Environment Canada has categorized triclosan as potentially toxic to aquatic organisms since it bioaccumulates (becomes more concentrated). Even at low concentrations in aquatic plants and animals, it can cause growth reduction and decreased reproduction, impacting survival. Triclosan’s structure is similar to thyroid hormones, so scientists have suggested triclosan’s mechanism of toxicity might involve binding to hormone receptors, impacting hormone functions.4

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Animal studies with triclosan have shown that mice exposed to antibacterial ingredients were more likely to develop liver cancer.8 Another study exposed triclosan to pregnant rats9 and found their hormone (progesterone, estradiol, testosterone) levels dropped, potentially affecting fetal development. Triclosan can interfere with normal thyroid hormone functions,10 raising concerns about reproductive impacts. However, no definitive study has proven how harmful triclosan is to humans.11

Triclosan is also persistent, meaning that it does not degrade easily.12 Once it is washed down the drain, most wastewater treatment plants cannot effectively filter out triclosan, and it enters our Great Lakes and waterways.

Lab studies with triclosan suggest it can randomly generate mutations in bacteria.13 This will likely lead to increasing antibiotic resistance in bacteria, creating “superbugs” and decreasing the effectiveness of antibiotics.

Why was triclosan (one of 19 active ingredients) banned in soaps by the FDA?

The FDA banned triclosan and other ingredients from soaps, because there is no compelling evidence the ingredients are safe.1 In 2013, the FDA asked manufacturers to submit evidence that antibacterial ingredients are safe for long-term use and more effective than regular soap at reducing the spread of germs. Neither was proven. Resulting research suggested triclosan and similar agents might be harmful.

“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,” said Dr. Janet Woodcock, director of the FDA’s Centre for Drug Evaluation and Research in a press release.1

While triclosan is useful in medical settings to protect against bacteria like MRSA, it is not necessary in consumer soaps. So, this ban applies to consumer products, not to antibacterial soaps used in hospitals and food service settings. Products not under the purview of the FDA (like toys, furniture, apparel) are not subject to the ban.

What is Canada’s response?

Health Canada has restricted the amounts of triclosan in mouthwash and personal care products, but has not banned the chemical.2 While concentration limits of triclosan are low (0.03% in mouthwashes, 0.3% in cosmetics),5 even these small amounts will bioaccumulate in our aquatic ecosystems.

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The Canadian government has announced that triclosan is not hazardous to human health, but has declared it toxic under the Environmental Protection Act because of its negative effect on aquatic organisms. Environment Canada has flagged triclosan for future assessment.6

Health Canada has said, “The health and safety of Canadians is of utmost importance… The government will continue to monitor new scientific evidence related to triclosan and will take further action if warranted.”

Canada does plan to introduce measures to limit the release of triclosan from consumer products into waterways.6 But this may prove more challenging as this requires manufacturers to develop plans and upgrade for waste-treatment equipment – a costly endeavor.

Many environmentalists and scientists are pushing for Canada to implement a ban of these chemicals in consumer products. In the meantime, should we, as Canadian consumers, refrain from buying antibacterial soaps?

“It really should not be left to the consumers to try to avoid these products, especially given that there is very little benefit to using them,” says Fe de Leon, Canadian Environmental Law Association researcher.7



Triclosan laboratory studies

  1. Feng, al. PLoS ONE 11(5).
  2. Yueh, M. F. et al. Proc Natl Acad Sci U S A 2014, 111(48), 17200.
  3. Gee, R. H. et al. Appl. Toxicol. 2008, 28, 78.
  4. Calafat, A. M. et al. Health Perspect. 2008, 116(3), 303.
  5. Ricart, M. et al. Toxicol. 2010, 100(4), 346.
  6. Pycke, B. F. G. et al. Appl. Environ. Mircobiol. 2010, 76(10), 3116.

Challenges in Designing Non-Toxic Molecules: Using medicinal chemistry frameworks to help design non-toxic commercial chemicals

By Shira Joudan, Education Committee Coordinator for the GCI

Throughout the past 20 years, there have been numerous reports on the state of the science of designing non-toxic molecules, including three in this year alone.1–3 The idea of safe chemicals has been around for much longer than the green chemistry movement, however it is an important pillar in what it means for a chemical to be green. In fact, many scientists agree that the synthesis of safer chemicals is likely the least developed area of Green Chemistry, with lots of room for improvement.2 For more information, see our post and video on Green Chemistry Principle #4.

One expert on designing non-toxic molecules is Stephen C. DeVishira-blog-picto of the United States Environmental Protection Agency (US EPA). In a recent paper DeVito highlights some major challenges creating safer molecules, and discusses how we can approach this challenge.1 We require a societal change about how we think of toxicity, and this shift must begin with specific education.

How can we agree upon definition of a “safe” chemical?

We need to decide and agree upon parameters that deem a molecule safe, or non-toxic. Generally, most chemists agree that an ideal chemical will have no (or minimal) toxicity to humans or other species in the environment. It should also not bioaccumulate or biomagnify in food chains, meaning it should not build up in biota, or increase in concentration with increased trophic levels in a food chain. After its desired usage, an ideal chemical should break down to innocuous substances in the environment. Potency and efficacy are also important, as well as the “greenness” of its synthesis. Setting quantitative thresholds to these parameters and enforcing them is the largest challenge.

How do we tackle the over 90,000 current use chemicals?

Although not all of these chemicals are actually in use, they are all registered under the US EPA’s Toxic Substances Control Act (TCSA), which contains both toxic and non-toxic chemicals. Many chemicals that are being used should be replaced with safer alternatives, but there are so many that it seems terrifying to know where to begin. Another replacement option is designing new technologies that don’t require the function that these chemicals provide. About two-thirds of the chemicals registered in TCSA or Environment and Climate Change Canada’s Chemicals Management Plan were in use before registration was required. Unlike pharmaceuticals and pesticides which are heavily regulated by Health Canada, commercial chemicals do not require stringent toxicity tests. But things are changing in the US and in Canada. For example, Canada has just listed 1550 priority chemicals that will be addressed by 2020. When considering replacement for chemicals of concern, the most common barrier to reducing the use is currently “no known substitutes or alternative technologies”.

How do we ensure sufficient training on the concepts of safer chemical design?

Many people making new chemicals are unfamiliar with green chemistry and basic toxicology principles. Without the proper toolbox of knowledge designing safer chemicals is challenging. [The Green Chemistry Commitment is a great place to start!] DeVito discusses the need for “toxicological chemists” which would be analogous to medicinal chemists, but instead produce non-toxic commercial chemicals. Medicinal chemists have the training to design appropriate pharmaceuticals, however commercial chemicals do not receive the same attention in terms of designing safe and efficacious products. Since humans are exposed to the commercial chemicals as well, often in intimate settings, the same attention to detail should be used during the synthetic process in order to produce safe chemicals.

Synthetic organic chemists are the ones designing the new chemicals, and we can no longer keep traditional chemists and toxicologists an arm’s length apart. Instead, there is a need for a new type of scientist that considers the function of the chemical for its desired usage and its toxicity potential to humans and the environment. Similar to the training of medicinal chemists, these chemists should receive training in biochemistry, pharmacology and toxicology, and also in environmental fate processes. DeVito suggests adding topics into an undergraduate curriculum, some of which are highlighted here:

  • Limit bioavailability: A common way to prevent toxicity has been to reduce the bioavailability of molecules. Essentially, the idea is that if the chemical cannot be absorbed into the bloodstream of humans or other species, it will not be able to cause significant toxic effects. A common predictor for bioavailability is the “Rule of 5”, where a molecule will have poor absorption if it contains more than five hydrogen bond donors or 10 hydrogen bond acceptors, a molecular weight of more than 500 amu, and a logP (or log Kow) of greater than 5.4 More sophisticated prediction methods also exist based on linear free energy relationships. A good example of low bioavailability is the artificial sweetener sucralose, where only 15% of the chemical is absorbed through the gastrointestinal tract into the bloodstream.5
  • Isosteric substitutions of molecular substituents: By removing parts of the molecule and replacing it with another functional group with similar physical and chemical properties (isosteric) toxicity can be reduced. This is common in medicinal chemistry, where it is referred to as bioisosterism, and is used to reduce toxicity, alter bioavailability and metabolism. A simple substitution can be replacing a hydrogen atom for a fluorine atom, but there can also be much larger isosteric substitutions.
  • Designing for degradation: A toxic molecule that persists in the environment can lead to global long term exposure. Understanding common environmental breakdown mechanisms can allow us to design molecules that will break down to innocuous products after their desired usage. A good starting point is understanding aerobic microbial degradation, since most of our waste ends up at a wastewater treatment plant. An important thing to keep in mind is that if a non-toxic molecule degrades to a toxic molecule, the starting material will still be of concern.

Toxicity is complicated. The best way to arm the next generation of chemists with the skills needed to design smart, safe chemicals is to tailor the undergraduate education to our new goals.

Numerous institutions, including the University of Toronto, are working towards this by signing onto the Green Chemistry Commitment!

(1)         DeVito, S. C. On the design of safer chemicals: a path forward. Green Chem. 2016, 18 (16), 4332–4347.

(2)         Coish, P.; Brooks, B. W.; Gallagher, E. P.; Kavanagh, T. J.; Voutchkova-Kostal, A.; Zimmerman, J. B.; Anastas, P. T. Current Status and Future Challenges in Molecular Design for Reduced Hazard. ACS Sustain. Chem. Eng. 2016, 4, 5900–5906.

(3)         Jackson, W. R.; Campi, E. M.; Hearn, M. T. W.; Collins, T. J.; Voutchkova-Kostal, A. M.; Kostal, J.; Connors, K. A.; Brooks, B. W.; Anastas, P. T.; Zimmerman, J. B.; et al. Closing Pandora’s box: chemical products should be designed to preserve efficacy of function while reducing toxicity. Green Chem. 2016, 18 (15), 4140–4144.

(4)         Lipinski, C. A.; Lombardo, F.; Dominy, B. W.; Feeney, P. J. Experimental and computational approaches to estimate solubility and permeability in drug discovery and development setting. Adv. Drug Deliv. Rev. 2001, 46, 3–26.

(5)         Roberts, A.; Renwick, A. G.; Sims, J.; Snodin, D. J. Sucralose metabolism and pharmacokinetics in man. Food Chem. Toxicol. 2000, 38, 31–41.

Goodbye Endocrine Disruption!

By Shivanthi Sriskandha, Member-at-Large for the GCI

A recent study published in the Royal Society of Chemistry journal, Green Chemistry, has aimed to bridge the gap between chemists and toxicologists in the design of safer, sustainable chemical products. The paper is authored by 23 scientists in the fields of green chemistry, biology, and environmental health science, and proposes a protocol to effectively develop compounds that will not cause endocrine disruption.

Oral contraceptives contain a combination of estrogen and progestogen, known EDCs that have implications on fish and other wildlife.

Endocrine disruption occurs when an agent or mixture of chemicals interferes with any aspect of hormone action. Common endocrine-disrupting chemicals (EDCs) include BPA, DDT, flame retardants, and phthalate-containing products. As such, the primary concern is exposure to these chemicals in consumer products. Research has now shown that EDCs can affect human metabolism, liver, and bone function as well as have an impact on diabetes, obesity, infertility, and learning disorders.

Currently, environmental performance and sustainability are not taken into account when designing new chemicals, or at least not emphasized enough. Furthermore, chemists have a limited knowledge of toxicology and therefore aren’t trained to evaluate toxicity risks. For these reasons, the Tiered Protocol for Endocrine Disruption, or TiPED, system was invented to guide chemists towards the design of safer materials.

Pesticides and herbicides used for agricultural and domestic purposes are common sources of EDCs.

The 5-tiered TiPED system combines principles in green chemistry with new methods of toxicology to form a comprehensive system that will evaluate a new chemical’s toxicity. The system is designed so that the user has the ability to enter the process at any stage in order to best meet the user’s needs. In each tier, a pass-fail grade is given to the chemical in question. If it passes, it is allowed to move onto the next stage for further testing. If it fails, it must go back to the drawing board to be reassessed. Since the current protocol cannot detect all possible mechanisms of endocrine disruption (an area of science that is still in progress), updates to the protocol will be made on the peer-reviewed TiPED website as they are developed.


The proposed tiered test for endocrine disruption, TiPED.[1]

Here’s how the Tiers work:

  • Tier 1: Computational approaches that can assess the chemical compound by searching existing databases for known EDCs and by predicting endocrine-disrupting behaviour using computer models.
  • Tier 2: Cell-based assays that directly test a chemical’s ability to interact with and affect the activity of targeted proteins, hormone receptors, and genes.
  • Tier 3: Assesses the activity of a test chemical on an endocrine-signaling pathway that may lead to cell division, differentiation or death, or to endocrine-mediated processes.
  • Tier 4: Determines chemical impacts on fish and amphibian reproductive cycles, development and behaviour.
  • Tier 5: Mammalian testing to mimic responses in humans.

Overall, consumer awareness of the harm in commercial products is leading to the development of safer chemicals and greater collaboration between various scientific disciplines to make our world a healthier place.

For further information, please see the companion website: where you can gain access to the paper and consult the formal protocol on the TiPED system.


[1] T. T. Schug et al., “Designing endocrine disruption out of the next generation of chemicals”, Green Chem. 2013, 15, 181-198.