The use of germicidal ultraviolet light, vaporized hydrogen peroxide and dry heat to decontaminate face masks and filtering respirators contaminated with a SARS-CoV-2 surrogate virus.

BACKGROUND: In the context of the ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the supply of personal protective equipment remains under severe strain. To address this issue, re-use of surgical face masks and filtering facepiece respirators has been recommended; prior decontamination is paramount to their re-use. AIM: We aim to provide information on the effects of three decontamination procedures on porcine respiratory coronavirus (PRCV)-contaminated masks and respirators, presenting a stable model for infectious coronavirus decontamination of these typically single-use-only products. METHODS: Surgical masks and filtering facepiece respirator coupons and straps were inoculated with infectious PRCV and submitted to three decontamination treatments, ultraviolet (UV) irradiation, vaporized H2O2, and dry heat treatment. Viruses were recovered from sample materials and viral titres were measured in swine testicle cells. FINDINGS: UV irradiation, vaporized H2O2 and dry heat reduced infectious PRCV by more than three orders of magnitude on mask and respirator coupons and rendered it undetectable in all decontamination assays. CONCLUSION: This is the first description of stable disinfection of face masks and filtering facepiece respirators contaminated with an infectious SARS-CoV-2 surrogate using UV irradiation, vaporized H2O2 and dry heat treatment. The three methods permit demonstration of a loss of infectivity by more than three orders of magnitude of an infectious coronavirus in line with the United States Food and Drug Administration policy regarding face masks and respirators. It presents advantages of uncomplicated manipulation and utilization in a BSL2 facility, therefore being easily adaptable to other respirator and mask types.

Wyman Chan: 'technically, I have been doing my job illegally for the past 20 years'. Interview by Ruth Doherty.

Wyman Chan talks to the BDJ about his mission to deliver pain-free whitening treatments and his views on the recent tooth-whitening legislation.

Labeled vs actual concentration of bleaching agents.

The purpose of this study was to determine if the actual concentration of bleaching agents available in four different countries were the same as the label indicated and within the recommendations of the International Standard on Tooth Whitening. The method recommended for assaying peroxide by the United States Pharmacopeia was used to determine concentrations. All products in the United States and China were within the standard when products were tested immediately upon delivery at testing sites. One product in Saudi Arabia and three products in Brazil had greater than 30% concentration loss. Three of 24 products in the United States did not meet the International Standard when they were tested at month of expiration.

Avaliação da microdureza e rugosidade superficial de uma resina composta submetida ao clareamento com peróxido de hidrogênio a 35% / Evaluation of microhardness and surface roughness of a composite resin under 35% hydrogen peroxide bleaching

Objetivo - Avaliar a microdureza e rugosidade superficial de uma resina composta microhíbrida à base de silorano, submetida ao clareamento imediato com peróxido de hidrogênio a 35%, autocatalisado, contendo cálcio. Métodos - Foram confeccionados 30 corpos de prova, divididos em 3 grupos experimentais: Grupo 1 (n=10): resina composta sem tratamento clareador; Grupo 2 (n=10): resina composta submetida a duas sessões de clareamento imediato com peróxido de hidrogênio a 35%; Grupo 3 (n=10): resina composta submetida a duas sessões de clareamento imediato com peróxido de hidrogênio a 35% com cálcio e armazenadas por 7 dias em saliva artificial a 37ºC. Foram realizados testes de rugosidade e microdureza para todos os grupos. Resultados - Os dados foram avaliados por análises de variância ao nível de significância de 5%, complementadas pelo teste de Tukey. Não houve diferença significativa entre os grupos quanto à rugosidade (p=0,481), ainda que a média do controle tenha sido maior do que dos outros grupos. Por outro lado, houve diferença significativa entre grupos quanto à microdureza (p=0,007). Os grupos G1 e G2 apresentaram médias de microdureza equivalentes e significativamente maiores do que a média do grupo G3. Conclusão - Pode-se concluir que, após o clareamento com peróxido de hidrogênio a 35% contendo cálcio, a rugosidade superficial da resina não se alterou e a microdureza diminuiu após uma semana de armazenamento em saliva artificial.

Objective - To evaluate the microhardness and surface roughness of a resin-based microhybrid silorano, subjected to bleaching with hydrogen peroxide 35%, self-catalyzed, containing calcium. Methods - There was prepared 30 specimens, divided into three groups: Group 1 (n = 10): composite without bleaching treatment, Group 2 (n = 10): composite subjected to two sessions immediately bleaching with hydrogen peroxide 35%, Group 3 (n = 10): composite subjected to two sessions immediately bleaching with hydrogen peroxide to 35% with calcium and stored for 7 days at 37°C in artificial saliva. Tests of roughness and hardness were performed for all groups. Results - Data were evaluated by analysis of variance at a significance level of 5%, complemented by the Tukey test. There was no significant difference between groups in terms of roughness (p = 0.481), although the average of the control was higher than the other groups. On the other hand, significant differences between groups in terms of microhardness (p = 0.007) were observed. The groups G1 and G2 showed average microhardness equivalent and significantly higher than the average of the group G3. Conclusion - It can be concluded that, after bleaching with hydrogen peroxide containing 35% calcium, the surface roughness of the resin did not change and microhardness decreased after one week storage in artificial saliva.

Disinfection of the hospital water supply: a hidden risk to dialysis patients.

Water suitable for drinking is unsuited for use in the preparation of haemodialysis fluid and undergoes additional treatment. The primary component of the additional treatment is reverse osmosis, which does not remove low-molecular-weight contaminants, and the water treatment system must contain carbon beds or filters to ensure effective removal of such contaminants. The recent article by Bek and colleagues highlights an unrecognised issue with respect to chemicals that may be added to the water within hospitals to ensure that the distribution network is free of pathogens (for example, Legionella, pseudomonas, and mycobacteria) and underlines the need for personnel responsible for dialysis in a renal or intensive care setting to be aware of any potential effects that disinfection of the hospital water treatment system may have on the product water used in the preparation of dialysis fluid. Such awareness requires communication and the sharing of information between clinical and facilities staff.

Evaluation of quality of hydrogen peroxide-based antiseptic solutions available in Dar es Salaam, Tanzania.

BACKGROUND: Hydrogen peroxide solutions of low concentrations are important antiseptics and deodorants used in hospitals and as home-remedies. The preparations have the disadvantage of being unstable when exposed to sunlight and when stored for a long time. They decompose slowly, releasing oxygen and water thus decreasing the available hydrogen peroxide for antimicrobial action. OBJECTIVE: To assess the quality of hydrogen peroxide solution-based antiseptics available in Dar es Salaam. METHODOLOGY: One hundred and sixty-five samples were collected at random from pharmacies and medical stores, and analysed. One hundred and forty samples were hydrogen peroxide solutions intended for wound cleansing and 25 samples were eardrops. Among these samples, 116 were from manufacturer A, 24 from manufacturer B and 25 samples of eardrops were from manufacturer C. RESULTS: Eighteen (26%) of the samples from medical stores failed to meet specifications. Of the 70 samples from pharmacies, 20 (29%) failed to meet the BP 2005 specifications. All the 25 samples of eardrops failed to comply with specifications. The average hydrogen peroxide contents (+/-SD) of the samples from medical stores and pharmacies were 6.6 +/- 0.6%, 6.8 +/- 0.4% w/v respectively. The difference was statistically significant (P < 0.05). CONCLUSION: A significant proportion of hydrogen peroxide products in the Dar es Salaam market is of poor quality. There is a need for continuous monitoring of the quality of hydrogen peroxide available in the city.

Optimising hydrogen peroxide measurement in exhaled breath condensate.

BACKGROUND: Exhaled breath condensate (EBC) analysis has been proposed as a non-invasive method of assessing airway pathology. A number of substances, including hydrogen peroxide (H2O2), have been measured in EBC, without adequate published details of validation and optimisation. OBJECTIVES: To explore factors that affect accurate quantitation of H2O2 in EBC. MATERIALS AND METHODS: H2O2 was measured in EBC samples using fluorometry with 4-hydroxyphenylacetic acid. A number of factors that might alter quantitation were studied including pH and buffering conditions, reagent storage, and assay temperature. RESULTS: Standard curve slope was significantly altered by pH, leading to a potential difference in H2O2 quantification of up to 42%. These differences were resolved by increasing the buffering capacity of the reaction mix. H2O2 added to EBC remained stable for 1 h when stored on ice. The assay was unaffected by freezing assay reagents. The limit of detection for H2O2 ranged from 3.4 nM to 8.8 nM depending on the buffer used. CONCLUSIONS: The reagents required for this assay can be stored for several months allowing valuable consistency in longitudinal studies. The quantitation of H2O2 in EBC is pH-dependent but increasing assay buffering reduces this effect. Sensitive reproducible quantitation of H2O2 in EBC requires rigorous optimisation.

Contamination levels of in-use disinfectants in a teaching hospital in Lagos, Nigeria.

In-use testing of the disinfectants; Hibitane (5% w/v Chlorhexidinegluconate), Hibiscrub (4% w/v Chlorhexidinegluconate), Savlon (3% w/v Chlorhexidine/Cetrimide), hydrogen peroxide (6% w/v hydrogen peroxide with stabilizer) and a common household bleach Jik (3.5% w/v sodium hypochlorite), was carried out over a two-month period at a university teaching hospital in Nigeria. Contamination levels were high with 82 (63.1%) of the 130 in-use disinfectants contaminated. However, a few of the stock solutions remained sterile. One hundred and thirty-four isolates were obtained of which 120 (91%) were gram-negative with Pseudomonas species being the commonest, constituting 67.2% of all the isolates. Gram-positive organisms made up the remaining 12 (9.0%) isolates. All the Pseudomonas spp. were resistant to gentamicin, ceftazidime, nalidixic acid and perfloxacin. Contributory factors for the high contamination levels were dilution of disinfectants with tap water, inadequate care of stock solution bottles and long storage of the diluted disinfectants in the wards.

Determination of hydrogen peroxide by micro-flow injection-chemiluminescence using a coupled flow cell reactor chemiluminometer.

A novel flow cell reactor was developed for micro-flow injection determination of hydrogen peroxide (H(2)O(2)) using horseradish peroxide (HRP)-catalysed luminol chemiluminescence. The newly developed flow cell reactor for a chemiluminometer allowed mixing of the chemiluminescent reagents in front of a photomultiplier for maximum detection of the emitted light. The rapid mixing allowed a decrease in the flow rate of the pump to 0.1-0.01 mL/min, resulting in increased sensitivity of detection of light. The flow cell reactor was made by packing HRP-immobilized gels into a flow cell (Teflon tube; 6 cm x 0.98 mm i.d.) located in the cell holder of a chemiluminometer (flow-through type). The HRP-immobilized gels were made by immobilizing HRP onto the Chitopearl gel by the periodate method. H(2)O(2) specimens (50 microL) were injected into a stream of water delivered at a flow rate of 0.1 mL/min and mixed with a luminol solution (0.56 mmol/L in Tricine buffer, pH 9.2) delivered at 0.1 mL/min in the flow cell reactor. Within-run reproducibility of the assay of H(2)O(2) was 2.4% (4.85 micromol/L; flow rate 0.1 mL/min, injection interval 10 min). The reproducibility of the H(2)O(2) assay was influenced by the flow rates and the injection intervals of the H(2)O(2) specimens. As the flow rates decreased, both the light intensity and the light duration increased. Optimal light intensity was obtained at a luminol concentration of 3-8 mmol/L, but 0.56 mmol/L was sufficient for assay of H(2)O(2) in clinical specimens. At a luminol concentration of 0.56 mmol/L, the regression equation of the standard curve for H(2)O(2) (0-9.7 micromol/L) was Y = 27.5 X(2) + 394 X + 58.9 (Y = light intensity; X = concentration of H(2)O(2)) and the detection limit of H(2)O(2) was 0.2 micromol/L. This method was used to assay glucose (2.7-16.7 mmol/L) based on a glucose oxidase (20 U/mL, pH 7.4) reaction. The standard curve for glucose was Y = 167 X(2) - 351 X + 1484 (Y = light intensity; X = glucose). The within-run reproducibility for an aqueous glucose standard (2.7 mmol/L) and a control serum (glucose, 5 mmol/L) was 4.48% (n = 5) and 5.70% (n = 9), respectively.

Comparative sensitivity of 13 species of pathogenic bacteria to seven chemical germicides.

BACKGROUND: The relative resistance of diverse human bacterial pathogens to commonly used germicidal agents has not been established. METHODS: We measured by titration the survival of thirteen different bacteria after exposure to glutaraldehyde, formaldehyde, hydrogen peroxide, peracetic acid, cupric ascorbate, sodium hypochlorite, or phenol. RESULTS: Our comparative experiments allowed classification of the organisms' survival into four groups: (a) Pseudomonas aeruginosa and Staphylococcus aureus showed the most resistance, (b) Clostridium perfringens, Salmonella typhimurium, Staphylococcus epidermidis, and Escherichia coli O157:H7 showed intermediate resistance, (c) Listeria monocytogenes, Shigella sonnei, and Vibrio parahaemolyticus survived some treatments with chemical agents only in the presence of protecting protein (serum albumin), and (d) Vibrio cholerae, Vibrio vulnificus, Bacillus cereus, and Yersinia enterocolitica did not survive any of the treatments applied. CONCLUSION: We found species that more frequently survived exposure to germicidal agents were also those most commonly reported in association with hospital infections. Our findings suggest that resistance to disinfectants may be more important than pathogenicity in determining the relative prominence of an organism as an agent responsible for nosocomial infections.

Chemical degradation of wastes of antineoplastic agents. 2: Six anthracyclines: idarubicin, doxorubicin, epirubicin, pirarubicin, aclarubicin, and daunorubicin.

OBJECT: Handling of genotoxic compounds commonly used in cancer chemotherapy generates contaminated wastes that require decontamination before disposal. Chemical methods are an alternative and/or a complement to incineration for the treatment of wastes and spills. METHODS: As part of a program initiated by the International Agency for Research on Cancer (IARC), 3 chemical methods readily available in the hospital environment--sodium hypochlorite (NaOCl, 5.25%), hydrogen peroxide (H2O2, < or = 30%) and Fenton reagent (FeCl2, 2H2O; 0.3 g in 10 ml H2O2, 30%)--are being tested for the degradation of a total of 32 antineoplastic agents. The efficiency of degradation was monitored by high-pressure liquid chromatography. The mutagenicity of the degradation residues were tested by the Ames test using tester strains Salmonella typhimurium TA 97a, TA 98, TA 100, and TA 102 with and without an exogenous metabolic activation system. RESULTS: The first results obtained for the degradation of cyclophosphamide, ifosfamide, and melphalan have been published in this journal. The present manuscript reports the results of the investigation of a series of six anthracyclines (aclarubicin, daunorubicin, doxorubicin, epirubicin, idarubicin, and pirarubicin) commonly used in chemotherapy treatment. Pharmaceutical preparations corresponding to the most concentrated administration solutions in either NaCl (0.9%) or dextrose (5%) were inactivated by oxidation volume/volume with each of the methods for at least 1 h. Complete degradation into nonmutagenic residues of all the tested compounds was observed after 1 h for the NaOCl (5.25%) treatment as previously reported for the first study. CONCLUSION: Sodium hypochlorite (5.25%) is an efficient reagent for the chemical degradation of the nine drugs tested thus far.

The pH of over-the-counter hydrogen peroxide in soft lens disinfection systems.

We evaluated the pH of six hydrogen peroxide (H2O2) soft lens disinfection systems which had over-the-counter (OTC) H2O2 substituted for the manufacturer's recommended H2O2. Substitution of four brands of OTC H2O2 into the five two-step disinfection systems resulted in a pH after neutralization which ranged from 6.70 to 7.55 pH units. There was a small but statistically significant difference in the pH after neutralization when OTC H2O2 was substituted for the manufacturer's recommended H2O2. There was a significantly lower pH after neutralization when the same brands of OTC H2O2 were substituted for the manufacturer's recommended H2O2 in a one-step H2O2 disinfection system. The pH after neutralization for the manufacturer's recommended H2O2 was 6.50 pH units. The pH after neutralization for the OTC H2O2 ranged from 3.35 to 4.77 pH units. This range is below the ocular comfort range of 6.6 to 7.8 pH units. These findings, along with other possible differences between OTC H2O2 and the manufacturer's recommended H2O2, indicate that OTC H2O2 should never be substituted for the manufacturer's recommended H2O2 in any H2O2 soft lens disinfection system.