IVL Swedish Environmental Research Institute

Background: During the COVID-19 pandemic, increased hand hygiene practices using water, soap and handdisinfectants, became prevalent, particularly among frontline workers. This study investigates the impact of thesepractices on the skin’s ability to retain the allergenic metals nickel, cobalt, and chromium. The study constitutesthree parts: (I) creating an impaired skin barrier, (II) exposing treated and untreated skin to nickel alone, and (III) inco-exposure with cobalt and chromium.

Methods: Using full-thickness skin from stillborn piglets, in vitro experiments were conducted to assess retention ofmetals in skin at conditions mimicking intense hand hygiene practices. Treatment of skin with varying concentrationsof sodium lauryl sulphate (SLS), to impair its barrier integrity was assessed. This was followed by exposure of treatedand untreated skin to the metals, that were dissolved in Milli-Q water, 0.5% SLS, and ethanol respectively.

Results: Results showed that pre-treatment with 5% SLS impaired the skin barrier with regards to the measure oftrans epidermal water loss (TEWL). Metal amounts retained in the skin were generally higher in treated than untreatedskin. The highest amounts of metal retained in skin were observed for exposure to nickel in ethanol. Co-exposure tonickel, cobalt, and chromium in 0.5% SLS resulted in the highest amounts of total metal retention.

Conclusions: The in vitro findings highlight the increased risk of metal retention in skin due to an impaired barrier.The SLS concentration used in the current study corresponds to those used in many hand hygiene products. Hence,occupational settings with frequent exposure to water, soap and disinfectants need to consider protective measuresnot only for the irritant exposures themselves but also simultaneous exposure to allergenic metals.