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Background: Cold plasma, a new treatment principle in dermatology based on ionic discharge delivering reactive molecular species and UV-light, exhibits strong antimicrobial efficacy in vitro and in vivo. Before implementing plasma as new medical treatment tool, its safety must be proven, as well as assessing skin tolerance and patient acceptance., Patients and Methods: We investigated the plasma effects of three different plasma sources (pulsed, non-pulsed atmospheric pressure plasma jet (APPJ) and a dielectric barrier discharge (DBD)) on the transepidermal water loss (TEWL) and skin moisture after treating the fingertips of four healthy male volunteers., Results: TEWL values were reduced by pulsed APPJ and DBD by about 20% but increased after non-pulsed APPJ by 5-20%. TEWL values normalized 30 min after all forms of plasma treatment. Skin moisture was increased immediately and 30 min after treatment with pulsed APPJ but was not affected by non-pulsed APPJ and DBD., Conclusions: All plasma treatments were well-tolerated and did not damage the skin barrier nor cause skin dryness. Cold plasma fulfils basic recommendations for safe use on human skin and as future option may serve as the first physical skin antiseptic., (© The Authors • Journal compilation © Blackwell Verlag GmbH, Berlin.)

The spray irrigation with pretreated wastewater was investigated on the sewage farm of the Braunschweig Sewage Utilization Association. The emission of airborne bacteria was measured by means of Andersen sampler (AS), Reuter centrifugal sampler (RCS), and sedimentation plates (SP). There was a good correlation of results obtained by parallel measurings of AS and RCS. The RCS was more effective by the factor 11.5 than the AS sampling airborne microorganisms. However, the AS gaves the distribution curve of differently big airborne particulates (Table 1). The medium decrease of bacteria from the sprinkler determined by AS and SP was similar (Fig. 1). With low wind velocity, an aerosol containing enterobacteria was yet detectable at a distance of 60-160 m down-wind from the spray sprinkler. The transport of bacteria as a function of the wind velocity is given in Fig. 2 increasing about 25 m for an increase of the wind velocity of 1 m/sec. During the spray irrigation, the composition of bacteria in the airborne particles is varying continuously. The following order of succession of die-away rates was found: Aeromonas, Plesiomonas, Vibrio greater than Acinetobacter, Pseudomonas greater than Enterobacter greater than Citrobacter greater than E. coli greater than Klebsiella greater than gram-positive bacteria (Table 3). Only seldom and under extreme conditions, gram-negative bacteria were detected in a range between 200-300 m beyond of concentrations as they were found also in controls without irrigation. This result substantiates a minimum protective distance of 300 m between sprinkler and human settlements.

The filtration of wastewater after irrigation by sandy soil in the area of The Braunschweig Sewage Utilization Association was investigated. For that purpose, the concentrations of gram-negative aerobe rods were determined in soil samples of 15 cm, 30 cm, 45 cm, 60 cm, 75 cm, 90 cm, 105 cm, 120 cm, 135 cm, and 150 cm depth immediately after an irrigation of about 50 mm wastewater during the vegetation (3 series), the vegetationless period (6 series), after one week (3 series) and after two weeks (3 series) during the vegetationless time. All enterobacteria were isolated and identified on the genus or species level (Table 1). Their concentration drops one order of magnitude per 20 cm soil down to a depth of 75 cm. In deeper soil layers the concentration of enterobacteria decreases one order of magnitude about per 60 cm. The enterobacteria penetrated to 60 cm during the vegetation and to 135 cm during the vegetationless period (Fig. 1). There is a relative increase of the fraction of Enterobacteriaceae and a relative decrease of Aeromonas and Plesiomonas as a function of the depth. The non-fermenter, i.e. Acinetobacter, Alcaligenes, and Pseudomonas remain constantly. Down to soil layers of 45 cm the Enterobacter increase relatively. E. coli increase also a little bit, whereas Citrobacter and Klebsiella decrease, respectively (Fig. 2, 3). Downwards, the ratio of Enterobacteriaceae shows no significant changes. Other Enterobacteriaceae, i.e. Proteus, Providencia, and Serratia constitute less than 10 percent. We have found none strains of Salmonella, Shigella, and Yersinia under 5105 enterobacteria identified.