I love a new, clean white, cotton t-shirt on my husband; that crisp brightness a t-shirt has when it is new. Funny thing, though: Cotton isn’t naturally bright white; it has a bit 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.
An interesting fact about optical brighteners are that they are not necessary. We don’t use them in our natural laundry detergent and yet the soap is still high performing and tough on dirt and stains. Read below 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.
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. While some degrade in sunlight, those that do not have direct sun exposure pollute the water as they do not biodegrade. In addition, optical brighteners can be toxic to some algae and small fish and can also bio-accumulate in larger fish.
Optical Brighteners and You
When optical brighteners are deposited onto clothing they come into contact with skin. A micro-climate is created between fabric and your skin. 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 photo-toxic skin irritation and in some cases photo-allergy. Although this is not a common occurrence, it has been reported in medical literature and consumers with sensitive skin may be more susceptible.