I just love a new, white, cotton t-shirt; a t-shirt so white that its glow can practically be seen from space. Funny thing, though: Cotton isn't fluorescent white; it has more of a yellow tone.
So how can a t-shirt look so white if it is 100% cotton? Chemistry of course! You can thank the optical brighteners that have been deposited on the fabric for that whiter-than-white glow.
But the most interesting thing is that optical brighteners are not necessary. We don't use them in Seventh Generation laundry detergents and yet the products are still high performing and tough on dirt and stains. Keep reading for the science behind "clean" clothes and its impact on you and the environment.
The Truth about Optical Brighteners
Optical brighteners are chemical ingredients added to laundry detergents that reflect light in a way that makes fabric look whiter than white.
In fact, new textiles, like t-shirts, typically contain optical brighteners. Washing clothes with laundry detergents that contain optical brighteners redeposit the reflective particles onto fabrics and allow them to once again trick the eye into seeing a vibrant white glow (1-3).
The Environmental Afterlife of an Optical Brightener
But there is more of a story here than seeing white that isn't really there. The waste matter from clothes that are washed with a laundry detergent containing optical brighteners enters the sewer system. The particles that aren't removed during the water treatment process enter our lakes and streams (4, 5). While some degrade in sunlight, those that do not have direct sun exposure pollute the water as they do not biodegrade (4-6). In addition, optical brighteners can be toxic to some algae and small fish and can also bioaccumulate in larger fish (7-9). That process looks something like this:
Optical Brighteners and You
When optical brighteners are deposited onto clothing they come into contact with skin. A microclimate is created between fabric and your skin (10). When you perspire, the moisture in the fabric releases optical brighteners and deposits them onto the skin. Because sunlight breaks down optical brighteners, this degradation process can happen on the skin when exposed to sunlight and result in phototoxic skin irritation and in some cases photoallergy (11, 12). Although this is not a common occurrence, it has been reported in medical literature and consumers with sensitive skin may be more susceptible (10).
Clean Clothes without Unnecessary Optical Brighteners
At Seventh Generation, we believe that if an action raises the threat of harm to health or the environment a different approach should be taken. This is part of a philosophy commonly referred to as the Precautionary Principle. In the case of optical brighteners, we choose not to use them in our laundry detergents because, as detailed, they raise the threat of harm to the environment and health. Luckily, we don't need to identify an alternative ingredient because optical brighteners are not necessary to formulate a high performance laundry detergent. In fact, Seventh Generation laundry detergents are still tough on dirt and stains and provide the performance you need without the optical brighteners that other leading laundry detergents contain.
- Chen H-C, Ding W-H. Hot-water and solid-phase extraction of fluorescent whitening agents in paper materials and infant clothes followed by unequivocal determination with ion-pair chromatography-tandem mass spectrometry. Journal of Chromatography A 2006: 1108: 202-207.
- Iamazaki E T, Atvars T D Z. Sorption of a Fluorescent Whitening Agent (Tinopal CBS) onto Modified Cellulose Fibers in the Presence of Surfactants and Salt. Langmuir 2007: 23: 12886-12892.
- Stana K K, Pohar C, Ribitsch V. Adsorption of whitening agents on cellulose fibers — Monitored by streaming potential measurements, calorimetry and fluorescence. Colloid & Polymer Science 1995: 273: 1174-1178.
- Kramer J B, Canonica S, Hoigne J, Kaschig J. Degradation of Fluorescent Whitening Agents in Sunlit Natural Waters. Environmental Science & Technology 1996: 30: 2227-2234.
- Poiger T, Field J A, Field T M, Siegrist H, Giger W. Behavior of fluorescent whitening agents during sewage treatment. Water Research 1998: 32: 1939-1947.
- Canonica S, Kramer J B, Reiss D, Gygax H. Photoisomerization Kinetics of Stilbene-Type Fluorescent Whitening Agents. Environmental Science & Technology 1997: 31: 1754-1760.
- Ganz C R, Schulze J, Stensby P S, Lyman F L, Macek K. Accumulation and elimination studies of four detergent fluorescent whitening agents in bluegill (Lepomis macrochirus). Environmental Science & Technology 1975: 9: 738-744.
- Sanchez-Meza J C, Pacheco-Salazar, V.F., Pavon-Silva, T.B., Guierrez-Garcia, V.G., Avila-Gonzalez, C.D.J., Guerrero-Garica, P. Toxicity assessment of a complex industrial wastewater using aquatic and terrestrial bioassays Daphnia pules and Lactuca sativa. Journal of Environmental Science & Health 2007: 42: 1425-1431.
- Sturm R N, Williams K E, Macek K J. Fluorescent whitening agents: Acute fish toxicity and accumulation studies. Water Research 1975: 9: 211-219.
- Rowe H D. Detergents, clothing and the consumer with sensitive skin. International Journal of Consumer Studies 2006: 30: 369-377.
- Gloxhuber C, Bloching H. Toxicological properties of fluorescent whitening agents. Clinical Toxicology 1979: 13: 728-733.
- Osmundsen P E. Contact dermatitis due to an optical whitener in washing products. British Journal of Dermatology 1969: 81: 799-803.