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benzalkonium chloride, chlorhexidine, cultured human epidermis, cytotoxic, hand disinfectants, keratinocytes, ozonated water, povidone-iodine



  1. Kashiwazaki, Jun DDS
  2. Nakamura, Kiwamu MD
  3. Hara, Yasuka MD
  4. Harada, Rie MMT
  5. Wada, Ikuo PhD
  6. Kanemitsu, Keiji MD


OBJECTIVE: To evaluate the cytotoxicity of various hand disinfectants and ozonated water to human keratinocytes using a cultured epidermal model.


DESIGN: Using a test protocol from the Organization for Economic Co-operation and Development, investigators applied hand disinfectants containing either 83% ethanol, 0.2% benzalkonium chloride, 0.5% povidone-iodine, 1% chlorhexidine, 1% chlorhexidine ethanol, or ozonated water to a cultured human epidermal model. Surface morphology and histologic changes were evaluated by scanning electron microscopy and hematoxylin-eosin staining.


MAIN OUTCOME MEASURES: Production of inflammatory cytokine interleukin 1[alpha] by keratinocytes and cell death rate.


MAIN RESULTS: Electron microscopic analysis revealed the creation of small holes on the stratum corneum, and hematoxylin-eosin staining revealed perinuclear vacuolation of keratinocytes and cells with a condensed nucleus. Interleukin 1[alpha] was detected in the culture supernatants. More than 80% of keratinocytes did not survive after a 15-minute application of disinfectants. However, no significant damage was detected with ozonated water.


CONCLUSIONS: Ozonated water did far less damage to keratinocytes than the tested disinfectants. Although the ability of ozonated water to disinfect hands of medical staff members requires further study, it might serve as an alternative with minimum cytotoxicity.