The Optical Illusion of Clean Clothes
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.
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- Osmundsen P E. Contact dermatitis due to an optical whitener in washing products. British Journal of Dermatology 1969: 81: 799-803.