Masters Crossfit rests with young son.

CrossFit Clothing: Lulu, Reebok and Anti-Microbial Fabrics

Silver nanoparticles are woven into high-tech athletic clothing as a means of controlling bacteria and odors.  How it kills bacteria is not completely understood, but it is believed to kill through oxidative stress.  Oxidative stress is harmful for us as well, but bacteria can be killed at lower levels.  Still, oxidative stress is not good.  That’s why anti-oxidants are protective against cancer and other forms of cell damage.  Silver nanoparticles are used in topical antibiotics to treat life threatening infections in burn patients.  Better to risk a little oxidative stress from silver nanoparticles than to die from an infection.So, is it a good idea to put silver nanoparticles in clothes? No one knows the answer to this question.  But there are a few answers to a few related questions.  For example, do the silver nanoparticles embedded in fabrics some off the cloth and end up in wastewater?  Do the particles come off the cloth and enter peoples bodies? Are there any known health effects from exposure to silver nanoparticles?  If the particles stay in the fabric there is probably little to worry about.  Let’s take a look:

  • Do Silver nanoparticles come off the fabrics in which they are embedded?  Apparently they do, but different fabrics lose nanoparticles at different rates, at least during the wash cycle.
  •  Can silver nanoparticles be absorbed into or through skin?  Apparently they can and have been shown to cause ill effects in laboratory tests of skin cells
  • How long do silver nanoparticles stay in a person once they get there?  This is an important question.  If they stay around a long time, they can do damage for a long time.  If they leave quickly they would be less dangerous.  Same thing goes for a lot of other substances.  The answer to this question appears to be unknown 
  • Are there any known health effects if silver nanoparticles are absorbed?  Silver nanoparticles appear to have harmful effects on some human (and animal) cells including nerve cells and interfere with synthesis of seleno-proteins.  Seleno-proteins are important anti-oxidants and detoxifying enzymes.  This means someone might show the effects of selenium deficiency even though dietary intake was adequate.

South Central CrossFit Regional Athlete Mackey Hermosillo finds an alternative means of protection against odor.

While its been demonstrated that the particles can harm cells, tissues or organs we don’t know how much would be needed to harm health.  The amount of silver nano-particles absorbed from clothing may not be high enough to matter.  Its an unanswered question.   We’ll probably hear more about this in coming years.  For now we recommend against using, eating or wearing things if we aren’t sure if they are going to bite us in the ass later.

Back to Lulu and Reebok and CrossFit Clothing.

Lulu Lemon uses silver nanoparticles for their anti-microbial fabrics.  We could not find any information on Reebok and silvernanoparticals, so we are assuming they are not using them.  On a positive note for Lulu, their silver nanopartical shirts really work for stink prevention.  We tested one by wearing it for two weeks straight on a challenging backpacking trip and it smelled fine.

Benn TM, & Westerhoff P (2008). Nanoparticle silver released into water from commercially available sock fabrics. Environmental science & technology, 42 (11), 4133-9 PMID: 18589977

Brandt O, Mildner M, Egger AE, Groessl M, Rix U, Posch M, Keppler BK, Strupp C, Mueller B, & Stingl G (2012). Nanoscalic silver possesses broad-spectrum antimicrobial activities and exhibits fewer toxicological side effects than silver sulfadiazine. Nanomedicine : nanotechnology, biology, and medicine, 8 (4), 478-88 PMID: 21839058

Lim DH, Jang J, Kim S, Kang T, Lee K, & Choi IH (2012). The effects of sub-lethal concentrations of silver nanoparticles on inflammatory and stress genes in human macrophages using cDNA microarray analysis. Biomaterials, 33 (18), 4690-9 PMID: 22459196.

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