Chlorine-containing Disinfectant Research Articles

Disinfection Strategies for Carbapenem-Resistant Klebsiella pneumoniae in a Healthcare Facility.

Disinfectant resistance is evolving into a serious problem due to the long-term and extensive use of disinfectants, which brings great challenges to hospital infection control. As a notorious multidrug-resistant bacterium, carbapenem-resistant Klebsiella pneumoniae (CRKP) is one of the most common and difficult pathogens of nosocomial infection. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests of seven kinds of disinfectants (0.1% benzalkonium bromide, 4% aqueous chlorhexidine, 75% alcohol, entoiodine II, 2% glutaraldehyde, 2000 mg/L chlorine-containing disinfectants, and 3% hydrogen peroxide) were detected by the broth dilution method. Three efflux pump genes (oqxA, oqxB, and qacE∆1-sul1) were detected by PCR. The mean MIC value of aqueous chlorhexidine from the intensive care unit (ICU) (0.0034%) was significantly higher than that from non-ICUs (0.0019%) (p < 0.05). The positive rates of three efflux pump genes oqxA, oqxB and qacE∆1-sul1 were 60.9% (39/64), 17.2% (11/64) and 71.9% (46/64) in the detected CRKP isolates, respectively. This study discovered that CRKP strains demonstrated extensive resistance to clinical disinfectants and suggest that it is necessary to perform corresponding increases in the concentration of aqueous chlorhexidine and chlorine-containing disinfectants on the basis of current standards in the healthcare industry.

Assessment of residual chlorine in soil microbial community using metagenomics

Chlorine-containing disinfectants have been widely used around the world for the prevention and control of the COVID-19 pandemic. However, at present, little is known about the impact of residual chlorine on the soil micro-ecological environment. Herein, we treated an experimental soil-plant-microbiome microcosm system by continuous irrigation with a low concentration of chlorine-containing water, and then analyzed the influence on the soil microbial community using metagenomics. After 14-d continuous chlorine treatment, there were no significant lasting effect on soil microbial community diversity and composition either in the rhizosphere or in bulk soil. Although metabolic functions of the rhizosphere microbial community were affected slightly by continuous chlorine treatment, it recovered to the original status. The abundance of several resistance genes changed by 7 d and recovered by 14 d. According to our results, the chlorine residue resulting from daily disinfection may present a slight long-term effect on plant growth (shoot length and fresh weight) and soil micro-ecology. In general, our study assisted with environmental risk assessments relating to the application ofchlorine-containing disinfectants and minimization of risks to the environment during disease control, such as COVID-19.Electronic supplementary materialSupplementary material is available in the online version of this article at 10.1007/s42832-022-0130-x and is accessible for authorized users.

Responses of aquatic organisms downstream from WWTPs to disinfectants and their by-products during the COVID-19 pandemic, Wuhan

The outbreak of COVID-19 has led to the large-scale usage of chlorinated disinfectants in cities. Disinfectants and disinfection by-products (DBPs) enter rivers through urban drainage and surface runoff. We investigated the variations in residual chlorine, DBPs, and different aquatic organisms in the Hanjiang, Fuhe, and Qinglinghe Rivers in Wuhan during the COVID-19 pandemic. The sampling sites were from the wastewater treatment plant outlets to the downstream drinking water treatment plant intakes. Total residual chlorine and DBPs (dichloromethane and trichloromethane) detected in the river water ranged from 0 to 0.84 mg/L and 0 to 0.034 mg/L, respectively. The residual chlorine and DBPs showed a gradual reduction pattern related to water flow, and the concentration at intakes did not exceed the Chinese drinking water source quality standards. Phytoplankton and zooplankton densities were not significantly correlated with residual chlorine and DBPs. The fluctuations in phytoplankton resource use efficiency (RUE) and zooplankton RUE in the Fuhe River, with the highest residual chlorine, and the Qinglinghe River with the highest DBPs, were higher than those in the Hanjiang River. For benthic macroinvertebrates, the number of functional feeding groups in the Hanjiang River was higher than that in the Fuhe and Qinglinghe Rivers. The water and sediment bacterial communities in the Hanjiang River differed significantly from those in the Fuhe and Qingling Rivers. The denitrification function involved in N metabolism was stronger in the Fuhe and Qinglinghe Rivers. Structural equation modelling revealed that residual chlorine and DBPs impacted the diversity of benthos through direct and indirect effects on plankton. Although large-scale chlorine-containing disinfectants use occurred during the investigation, it did not harm the density of the detected aquatic organisms in water sources. With the regular use of chlorinated disinfectants for indoor and outdoor environments in response to the SARS-CoV-2 globally, it is still necessary to study the long-term and accumulated responses of water ecosystems exposed to chlorine-containing disinfectants.

Оценка эффективности средств химической дезинфекции в отношении вируса Эпштейна-Барр

The widespread spread of infection caused by the Epstein-Barr virus (EBV), the lack of registered vaccines, the possibility of implementing a transmission mechanism in medical organizations, determine disinfection as the main method of preventing this disease. The aim is to evaluate the effectiveness of chemical disinfection agents approved for use in the Russian Federation in relation to EBV-infected cell culture with quantitative DNA determination by polymerase chain reaction. Working solutions of complex disinfectants used for the treatment of medical devices were introduced into samples of EBV-infected B-cell culture in the concentration and exposure specified in the instructions (0.1 %; 60 min.). Then, the quantitative determination of the EBV DNA was performed. Chlorine-containing disinfectants, combined preparations based on aldehydes and guanidines per hour, as well as guanidines per hour and triamines, provided complete destruction of genetic material, while the combination of H with triamines led only to a decrease in the concentration of EBV DNA from 5.0 · 106 copies/ml to 2.4 · 106 copies/ml (by 2.1 times), which may not be enough to fully ensure biological safety when processing medical devices (sensors of ultrasound diagnostics devices, etc.), which are not subject to sterilization. The inability to determine the viability of EBV after treatment with disinfectants due to the initial presence of the virus in the B-cell culture makes the molecular biological method the only acceptable one at this stage and requires the search for new models – cell cultures intact to EBV or biological objects (laboratory animals). Keywords: Epstein-Barr virus, disinfection, quaternary ammonium compounds, triamines, aldehydes, guanidines, active chlorine releasing agents.

High concentrations of hypochlorous acid-based disinfectant in the environment reduced the load of SARS-CoV-2 in nucleic acid amplification testing.

During the severe acute respiratory syndrome coronavirus type 2 (SARS‐CoV‐2) pandemic, chlorine‐containing disinfectants have been widely used in nucleic acid amplification testing laboratories. Whether the use of disinfectants affect the results of viral nucleic acid amplification is unknown. We examined the impact of different hypochlorous acid (HOCl) concentrations on the quantitative results of SARS‐CoV‐2 by real‐time reverse‐transcription polymerase chain reaction (RT‐PCR). We also explored the mechanisms and models of action of chlorine‐containing disinfectants that affected the detection of SARS‐CoV‐2. The results showed that different HOCl concentrations and different action times had an impact on the SARS‐CoV‐2 results. High concentrations of ambient HOCl have a greater impact than low concentrations, and this effect will increase with the extension of the action time and with the increase in ambient humidity. Compared with the enzymes or the extracted RNA required for RT‐PCR, the impact of HOCl on the SARS‐CoV‐2 detection is more likely to be caused by damage to primers and probes in the PCR system. The false negative result still existed after changing the ambient disinfectant to ethanol but not peracetic acid. The use of HOCl in the environment will have an unpredictable impact on the nucleic acid test results of SARS‐CoV‐2. In order to reduce the possibility of false negative of SARS‐CoV‐2 nucleic acid test and prevent the spread of epidemic disease, environmental disinfectants should be used at the beginning and end of the experiment rather than during the experimental operation.

Bromine and iodine species in drinking water supply system along the Changjiang River in China: Occurrence and transformation

Bromine (Br) and iodine (I) in source water can form highly toxic brominated or iodinated disinfection byproducts in treatment plants. For the first time, the occurrence of Br and I speciation and their proportion, transformation in the drinking water supply system along the Changjiang River were investigated. 96 water samples were collected from eight drinking water treatment plants under conditions of low, normal, and flood water regimes. Total Br (TBr) and total I (TI) concentrations were quantified by inductively coupled plasma mass spectrometry (ICPMS) and inorganic Br/I forms (bromide, bromate, iodide, and iodate) were determined by high-performance liquid chromatography coupled with ICPMS. Concentrations of organic Br/I were calculated as the difference between total Br/I and inorganic Br/I. Water regimes had different effect on Br and I species, and there were different rules in untreated and treated water samples. Apparent increase of TBr and TI concentrations after water treatment were observed, which indicated the possibility of Br/I introduction by chlorine-containing disinfectant. The occurrence of TBr, TI, bromide, and total organic I in the river were investigated to increase with the direction of flow. In addition, TBr and TI concentrations correlated with the concentrations of artificial sweeteners (e.g., acesulfame and sucralose, a kind of wastewater indicator), suggesting the influence of domestic sewage on Br and I in the river. In untreated water, bromide was the main Br species, and after treatment more than 50% was transformed into organic Br. Iodoorganics were the majority of I species in raw water and were partly transformed into iodate after treatment. Overall, the Br/I species have accumulation potential in the Changjiang River and organic forms occupy high proportion in treated water samples, which should be paid more attention.

CORROSION OF STAINLESS STEELS IN CHLORINE-CONTAINING DISINFECTANT SOLUTIONS

The results on the corrosion resistance of stainless steels 304 and 316 in 2% solutions of chlorine-containing disinfectants are presented. For analysis, we used the definition of open-circuit potentials from the exposure time and the measurement of corrosion currents. The change in the composition and morphology of the treated surfaces was studied using scanning electron microscopy with elemental analysis. &nbsp; &nbsp; &nbsp;

Evaluation of sensitivity to chemical disinfectants of mycobacterium tuberculosis strains isolated from HIV-infected individuals and patients with monotuberculosis infection compared to the reference strain

Objective. To study the sensitivity to chemical disinfectants against Mycobacterium tuberculosis isolated from HIV-infected individuals and patients with monotuberculosis in comparison to the reference strain of Mycobacterium terrae.&#x0D; Materials and methods. The sensitivity of 12 M. tuberculosis strains isolated from patients with HIV-associated tuberculosis (n = 6) and monotuberculosis (n = 6) to chlorine-containing and quaternary ammonium compound (QAC) disinfectants was studied. The M. terrae strain was used as a reference. Seedings of microbial suspensions treated with disinfectants on the culture medium Levenshtein-Jensen were carried out and were monitored for 3 months.&#x0D; Results. One, two, three months following the treatment of microorganisms with QAC-containing disinfectant in the absence of growth of the control strain, there was noted growth of M. tuberculosis, particularly intense in the strains isolated from HIV-infected persons.&#x0D; Conclusions. Thus, the resistance of tuberculosis pathogens to disinfectants can be acquired.&#x0D; M. tuberculosis strains isolated from patients with HIV-associated tuberculosis are detected to be more resistant to disinfectants than the strains isolated from patients with monotubercular infection.

Chlorine and the Chemistry of Disinfectants

The onset of COVID-19 pandemic has suddenly rendered disinfectants an essential class of substances for daily use globally. The demand for different disinfectants has rapidly surged, and it is important that the users of disinfectants are aware of the chemicals present in them, their properties, and how these disinfectants were introduced for public use. The history and development of chlorine-containing disinfectants and their possible modes of action have been explained in this article. The development and current status of hypochlorite-based compounds and chlorinated phenol-based compounds as disinfectants are also discussed in detail. The article explores the pros and cons of having chlorine in disinfectants and also looks critically at the future of such disinfectants based on safety and environmental considerations.

Anthropogenic emissions of atomic chlorine precursors in the Yangtze River Delta region, China

Chlorine radical plays an important role in the formation of ozone and secondary aerosols in the troposphere. It is hence important to develop comprehensive emissions inventory of chlorine precursors in order to enhance our understanding of the role of chlorine chemistry in ozone and secondary pollution issues. Based on a bottom-up methodology, this study presents a comprehensive emission inventory for major atomic chlorine precursors in the Yangtze River Delta (YRD) region of China for the year 2017. Four primary chlorine precursors are considered in this study: hydrogen chloride (HCl), fine particulate chloride (Cl−) (Cl− in PM2.5), chlorine gas (Cl2), and hypochlorous acid (HClO) with emissions estimated for twelve source categories. The total emissions of these four species in the YRD region are estimated to be 20,424 t, 15,719 t, 1556 and 9331 t, respectively. The emissions of HCl are substantial, with major emissions from biomass burning and coal combustion, together accounting for 68% of the total HCl emissions. Fine particulate Cl− is mainly emitted from industrial processing, biomass burning and waste incineration. The emissions of Cl2 and HClO are mainly associated with usage of chlorine-containing disinfectants, for example, water treatment, wastewater treatment, and swimming pools. Emissions of each chlorine precursor are spatially allocated based on the characteristics of individual source category. This study provides important basic dataset for further studies with respect to the effects of chlorine chemistry on the formation of air pollution complex in the YRD region.

ОСНОВНЫЕ НАПРАВЛЕНИЯ НАУЧНОЙ ДЕЯТЕЛЬНОСТИ ПО ОБЕСПЕЧЕНИЮ ВЕТЕРИНАРНО-САНИТАРНОГО БЛАГОПОЛУЧИЯ ЖИВОТНОВОДСТВА

The article presents the results of research work on the state order for 2020 on disinfection, including aerosol, and deratization. The prospects of fundamental research on the study of the effect of biological (bacteriophages) and chemical (chlorine-containing disinfectants) agents on biofilms of pathogenic and opportunistic microorganisms in order to select and evaluate new effective disinfectants are shown.

Development of Cryogenic Disinfectants Using in -18 °C and -40 °C Environments - Worldwide, 2021.

Introduction: Since the outbreak of coronavirus disease 2019 (COVID-19) in Beijing Xinfadi Wholesale Market, a series of COVID-19 outbreaks has indicated the threat of transmission due to outer surfaces of objects under low temperatures. Therefore, 2 kinds of chlorine-containing disinfectants for -18 degrees C and -40 degrees C were developed in order to solve the problem of low temperature disinfection. Methods: The properties of two cryogenic disinfectants were evaluated by low-temperature test. Staphylococcus aureus and Escherichia coli were used as two indicator microorganisms to evaluate the effects of the two cryogenic disinfectants in the laboratory and field tests according to Technical Specifications for Disinfection (2002 version) and Test method for bactericidal effect of disinfectants in laboratory (GB/T 38502-2020). Results: Two disinfectants could remain in the liquid state at -18 degrees C or -40 degrees C in 72 hours without crystallization and precipitation, and the average log values of microbial reduction before and after disinfection (the average killing log value) both on Staphylococcus aureus and Escherichia coli were >3 in the laboratory and field tests. Discussion: The results showed that these two disinfectants remained functional at low temperature to disinfect the packaging of imported cold chain food and surrounding packaging to prevent transmission of COVID-19 from material to people.

Environmental Disinfection Strategies to Prevent Indirect Transmission of SARS-CoV2 in Healthcare Settings

(1) Introduction: The novel respiratory syndrome coronavirus 2 (SARS-CoV-2), also called coronavirus disease 2019 (COVID-19), is rapidly spreading in many countries and represents a public health emergency of international concern. The SARS-CoV-2 transmission mainly occurs from person-to-person via respiratory droplets (direct transmission route), leading to the onset of mild or severe symptoms or even causing death. Since COVID-19 is able to survive also on inanimate surfaces for extended periods, constituting an indirect transmission route, healthcare settings contaminated surfaces should be submitted to specific disinfection protocols. Our review aimed to investigate the existing disinfection measures of healthcare settings surfaces, preventing the nosocomial transmission of SARS-CoV-2. (2) Materials and Methods: We conducted electronic research on PubMed, Scopus, Science Direct, and Cochrane Library, and 120 items were screened for eligibility. Only 11 articles were included in the review and selected for data extraction. (3) Results: All the included studies proposed the use of ethanol at different concentrations (70% or 75%) as a biocidal agent against SARS-CoV-2, which has the capacity to reduce the viral activity by 3 log10 or more after 1 min of exposure. Other disinfection protocols involved the use of chlorine-containing disinfectant, 0.1% and 0.5% sodium hypochlorite, quaternary ammonium in combination with 75% ethanol, isopropyl alcohol 70%, glutardialdehyde 2%, ultraviolet light (UV-C) technology, and many others. Two studies suggested to use the Environmental Protection Agency (EPA)-registered disinfectants, while one article chooses to follow the WST-512-2016 Guidance of Environmental and Surfaces Cleaning, Disinfection and Infection Control in Hospitals. (4) Conclusion: Different surface disinfection methods proved to reduce the viral activity of SARS-CoV-2, preventing its indirect nosocomial transmission. However, more specific cleaning measures, ad hoc for the different settings of the healthcare sector, need to be formulated.

Analysis of the Virus Contamination and Disinfection Effect in Isolation Ward of Patients With COVID-19.

The recent outbreak of COVID-19 has infected a large number of patients, increasing the importance of adequate disinfection of the hospital environment. We conducted this study to explore environmental virus contamination and the effect of terminal disinfection in the isolation ward of patients with COVID-19. A swab kit was used to sample various surfaces in the isolation and observation wards using the smear method. The samples were immediately sent to the PCR department of the laboratory for nucleic acid detection of COVID-19. We analyzed 31 high-frequency contact sites in three isolation wards of actively sick patients, of which seven were positive (22.58%, 7/31). Positive sites included the transfer window, bed rail, buffer room door handle, toilet door handle, and toilet faucet. All 55 samples taken from the wards of cured patients and the wards after terminal disinfection were negative. Virus contamination in areas frequently touched by patients in the isolation ward was high, so the awareness of correct disinfection must be increased. Use of 1,000–2,000 mg/L chlorine-containing disinfectant in the isolation ward was effective.

Management plan of a paediatric outpatient department during the SARS-CoV-2 epidemic.

With the novel coronavirus (2019-nCoV) infection outbreak and spread, serious cases of infection and neonatal infection have been reported. Moreover, children show milder cases and a better prognosis than adults. The outpatient Department of Paediatrics has played a crucial role in the prevention and control of novel coronavirus (2019-nCoV) infection in children. Based on previous experience and existing diagnosis and treatment guidelines, we present the relevant strategies of this particular paediatric outpatient department when responding to the epidemic. Conclusion: Concurrently, we hope that this article can act as a reference in the fight against SARS-CoV-2 infection. Further modifications will be made in the future with the increase in clinical experience and changes in the disease. This article is protected by copyright. All rights reserved.

Role of disinfection and hand hygiene: a COVID-19 perspective

Coronavirus disease 2019 (COVID-19) being an acute respiratory disease caused by a novel coronavirus (SARS-CoV-2) is transmitted in most instances through respiratory droplets, direct contact with cases, and also through contaminated surfaces/objects. Though the virus survives on environmental surfaces for varied periods, it gets easily inactivated by disinfectants. Therefore, this article aims to highlight the role of surface disinfection and hand disinfection during the COVID-19 pandemic. Disinfection with appropriate and recommended physical or chemical disinfectants will not only reduce the spread of the disease but also play a significant part in flattening the curve. Alcohol-based disinfectants and other chemical disinfectants play major roles. Ether, ethanol, hydrogen peroxide, sodium hypochlorite, other chlorine-containing disinfectants, peracetic acid, chloroform used under appropriate concentrations and techniques are necessary to stop the chain of transmission. Hand disinfection using soap and water or alcohol-based hand rubs are also of equal importance. Irrespective of the importance, the judicious use of disinfectants is also necessary. Therefore, the fastest, easiest, and most effective way to halt or reduce the spread of SARS-CoV-2 the virus resulting in the coronavirus disease (COVID-19) is through surface disinfection and handwashing with soap and water and its role in the COVID-19 pandemic is highly important.

DETERMINATION OF STANDARDIZED DOSES OF ULTRAVIOLET DISINFECTION OF WATER FROM BACTERIAL, VIRAL AND PARASITIC CONTAMINATION

Introduction. The proposed criteria for the sanitary-bacteriological assessment of the quality of tap water must ensure its epidemic safety. In conditions of intensive bacterial contamination of water bodies, a special role is played by the barrier function of water treatment plants in relation to infectious agents. The overall quality of microorganisms is the pronounced resistance in the aquatic environment, primarily resistance to a number of chlorine-containing disinfectants, which guarantee the preservation of the population in drinking water undergone a water treatment system. Therefore, it is necessary to consider other possible ways of disinfection, such as ultraviolet irradiation. Determination of the effective dose of ultraviolet (UV) disinfection against bacterial, viral and parasitic contamination of drinking water. Material and methods. Tap water was used as model water for research. The effectiveness of UV irradiation with doses of 25, 40, 60 mJ / cm2 against microorganisms was studied. Results. In the course of the work, it was established that the UV disinfection technology with a dose of at least 25 mJ/cm2 can be recommended as a disinfection method when used in conjunction with chlorination. Conclusion. In water treatment technology, a dose of at least 25 mJ/cm2 of UV irradiation can be recommended as a method of disinfecting water in case of microbial contamination by bacteria and viruses at a concentration not exceeding nˑ102 cells/virions in 100 ml, and at a concentration of microbiological contamination nˑ103 cells/virions in 100 ml of water, the use of UV disinfection can be recommended only in conjunction with chlorination and with the provision of indices on the residual chlorine in the distribution network before serving to the consumer. The presented scheme will increase the barrier role of water treatment facilities with respect to viral and bacterial contamination, provide a prolonged decontamination effect, contributing to the suppression of bacterial growth in breeding nets and limit the level of parasitic water contamination during water treatment.

An emission inventory for Cl2 and HOCl in Shanghai, 2017

Chlorine radical plays an important role in ozone formation. However, it has not generally been included in air quality modelling in China. In this study, an emission inventory for atomic chlorine precursors was developed for Shanghai in the year 2017. Total emissions of chlorine radical precursors were estimated at 8650 tons/year. The main source sectors of chlorine precursors in Shanghai include the volatilization of disinfectants, including in water treatment (850 tons/year, accounting for 9.8% among total emissions), in cooling towers (4,000 tons/year, 46.2%), in wastewater treatment (2,700 tons/year, 31.2%), in tap water (310 tons/year, 3.6%), in swimming pools (280 tons/year, 3.2%), and in the usage of chlorine-containing disinfectants (210 tons/year, 2.4%). The contribution of sea salt heterogeneous reactions with ozone to chlorine radical precursors is estimated as 90 tons/year; this represents a lower bound on the emissions from sea salt because of other reaction pathways (e.g., the reaction of particulate chloride with N2O5). Local emissions from coal combustion and chemical manufacturing were estimated to be relatively small. This study provides a basis for further study regarding the influence of chlorine chemistry on ozone formation in Shanghai.

Investigation of the influence of chlorine-containing disinfectant type on the quality of drinking water and the effectiveness of water treatment technology

Introduction. Effectiveness and applicability of chlorine-containing disinfectants used in the practice of water treatment were studied for the purpose of solving urgent environmental problems associated with the formation of secondary pollutants generated during the chlorination of natural water. Such contaminations are mostly represented by organohalogen compounds producing strong negative effect on the physiological state of living organisms, including human beings. To solve this problem, it is proposed to use technical grade sodium hypochlorite instead of traditional liquid chlorine when selecting disinfectants for natural water. Technical grade sodium hypochlorite is obtained by saturating solutions of diaphragmatic sodium hydroxide with chlorine gas at the stage of liquefaction of chlorine and caustic soda production. Sodium hypochlorite solution is significantly less toxic, non-flammable and not explosive. Materials and methods. A comparative study was conducted as to changes in the content of organohalogen compounds and heavy metals in water treated with sodium hypochlorite and liquid chlorine of one year duration. Analyses of water samples of water treated with liquid chlorine and sodium hypochlorite were made to measure concentrations of heavy metals, organohalogen compounds and other drinking water quality indicators, as specified by current regulations. Results. The obtained data demonstrate that the use of sodium hypochlorite for disinfection provides a higher quality of drinking water, therefore, it is advisable to replace liquid chlorine with technical grade sodium hypochlorite in the process of water treatment as potable water. Conclusions. The results of the study formed the basis for numerous industrial tests and subsequent implementation in existing water treatment plants in many large cities of Russia.

ПРОФЕССИОНАЛЬНАЯ ЗАБОЛЕВАЕМОСТЬ МЕДИЦИНСКИХ РАБОТНИКОВ ПРИМОРСКОГО КРАЯ (2005-2014 ГГ.)

The level of occupational morbidity rate of medical workers in governmental and multidisciplinary infectious medical institutions of the Primorsky Krai was studied according to reporting forms for the period of 2005-2014. The aim of the study was to investigate occupational morbidity rate of medical personnel to improve the management of health workers and to develop preventive programs for its reduction. Annual surveys of the medical staff for the carriage of viral hepatitis B, C, vaccinal prevention of hepatitis B; reduction of the use of chlorine-containing disinfectants; replacing latex gloves by nitrile, vinyl hypoallergenic medical gloves to protect hands of personnel allowed to significantly reduce the occupational morbidity rate.