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

References

  1. https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm205999.htm
  2. https://www.canada.ca/en/health-canada/services/chemicals-product-safety/triclosan.html
  3. http://blog.nacwa.org/washing-away-triclosan-with-legislation-and-regulation/
  4. http://www.environmentalhealthnews.org/ehs/news/triclosan-and-dolphins
  5. http://www.hc-sc.gc.ca/cps-spc/cosmet-person/labelling-etiquetage/ingredients-eng.php#a4.14
  6. http://www.chemicalsubstanceschimiques.gc.ca/fact-fait/glance-bref/triclosan-eng.php
  7. http://www.cbc.ca/news/technology/ban-antibacterials-triclosan-and-triclocarban-report-says-1.2703095
  8. http://www.ewg.org/release/fda-finally-bans-toxic-triclosan-antibacterial-hand-soaps

Triclosan laboratory studies

  1. Feng, Y.et 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.

Green Chemistry Principle #8: Reduce Derivatives

By Trevor Janes, Member-at-Large for the GCI

8. Unnecessary derivatization (e.g. installation/removal of use protecting groups) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.

In Video #8, Cynthia and Devon look at one common example of derivatization, which is the use of protecting groups in chemical reactions. To help illustrate the concept of a protecting group, they use toy building blocks.

In this blog post, I will use cartoons such as the one shown below (a specific example of the use of protecting groups will be shown at the end of this post).

Principle 8 - unselective reaction

Figure 1 An unselective reaction.

In Figure 1, the starting material contains two reactive sites, represented by U-shaped slots. We only want the slot on the right to react with the reagent, shown as red circles. The starting material is reacted with the reagent in order to make the desired product, but an undesired product also forms, because both U-shaped slots react with the red circle. In other words, Figure 1 shows an unselective reaction because a mixture of products is made.

Formation of the undesired product can be avoided by carrying out a protection reaction before using the red reagent, and then carrying out a final deprotection reaction. This sequence of reactions is shown in Figure 2.

Principle 8 - selectivity through protecting groups

Figure 2 A selective reaction through the use of a protecting group, which temporarily blocks the reactive site on the left side. 

 

Figure 2 shows how a selective reaction is traditionally done – through the use of a temporary block, known as a protecting group. The starting material can be protected by blocking one of the reactive sites, represented by the blue rectangle covering the U-shaped slot on the left. This intermediate only has one reactive site left, so the second reaction with the red reagent can only happen at the empty U-shaped slot on the right. To get the same desired product as in Figure 1, the third and final deprotection step is carried out, which removes the protecting group.

Principle 8 - waste from protecting groups

Figure 3 The waste created by all three reactions in Figure 2.

Even though the product from Figure 2 is the desired product, we had to do three reactions to only make one change, which is inefficient. Also, each step generates waste products (shown underneath each reaction arrow in the above cartoon) , which are depicted in Figure 3.

Protecting groups are a useful tool that chemists use to make the molecules, because we often need to carry out selective reactions on a molecule that has multiple of the same reactive sites. However, as we have talked about here, they are also inefficient and wasteful.

An active area of research is the development of more selective reactions, which eliminate the need to use protecting groups altogether.[1] Selective reactions use slight differences in a molecule’s chemistry to make a reaction happen at only the desired reactive site. This is very similar to the installation of the protecting group in Figure 2.

As more and more highly selective reactions are discovered, our syntheses can be made more efficient by reducing the number of steps required and the amount of waste produced. Looking ahead, protecting groups will be less and less necessary – and that’s a good thing!

 

Appendix – Example from Real Chemistry

A simple, specific example of the use of protecting groups[2] is shown below. Both oxygen-containing sites are reactive, but we only want the one on the left side to react in this case. The first reaction is the installation of the protecting group, (CH3)3SiCl, on the OH oxygen only, protecting the right side. The second reaction shows the reagent, CH3CH2CH2MgBr (for those curious, this is called a Grignard Reagent), which now reacts with just the ketone C=O site on the left, adding the desired new CH3CH2CH2 segment. The last step shows a combination of removing the protecting group to return the OH group, and also removing the [MgBr] segment of the reagent with the help of acid (shown as H3O+), which leaves the desired product with a CH3CH2CH2 chain added only on one side of the molecule.

Principle 8 - real protecting group use in chemistry

This example of a selective reaction uses a protecting group, but this requires 3 steps to only make 1 change. Instead, we can eliminate the need for protecting groups by designing new and more selective reactions that are much more efficient.

References:

[1] I. S. Young and P. S. Baran, Nature Chem. 2009, 1, 193

[2] R. J. Ouellette and J. D. Rawn, in Organic Chemistry, 2014, Elsevier, Boston pp 491-534.