Increased disinfection byproducts in the air resulting from intensified disinfection during the COVID-19 pandemic

Assessment of immunomodulatory effects of five commonly used parabens on human THP-1 derived macrophages: Implications for ecological and human health impacts

Parabens are widely used as broad-spectrum anti-microbials and preservatives in food, cosmetics, pharmaceuticals, and personal care products. Studies suggest that the utilization of parabens has substantially increased over the past years, particularly during the global pandemic of coronavirus disease 2019 (COVID-19). Although parabens are generally recognized as safe by the U.S. FDA, some concerns have been raised regarding the potential health effects of parabens associated with immunotoxicity. Herein, we comprehensively investigated several key characteristics of immunotoxicants of five commonly used parabens (methyl-, ethyl-, propyl-, butyl-, and benzyl parabens) in human THP-1 derived macrophages, which are effector cells serving as a first line of host defense against pathogens and tumor immunosurveillance. The results indicate parabens, at concentrations found in humans and biota, significantly dampened macrophage chemotaxis and secretion of major pro-inflammatory cytokines (TNF-α and IL-6) and anti-inflammatory cytokine (IL-10), corroborating the mRNA expression profile. Furthermore, some parabens were found to markedly alter macrophage adhesion and cell surface expression of costimulatory molecules, CD80+ and CD86+, and significantly increase macrophage phagocytosis. Collectively, these findings heighten awareness of potential immunotoxicity posed by paraben exposure at biologically relevant concentrations, providing implications for human health and ecological risks associated with immune dysfunctions.

Assessment of chlorine and hydrogen peroxide on airborne bacteria: Disinfection efficiency and induction of antibiotic resistance

Airborne pathogens severely threaten public health worldwide. Air disinfection is essential to ensure public health. However, excessive use of disinfectants may endanger environmental and ecological security due to the residual disinfectants and their by-products. This study systematically evaluated disinfection efficiency, induction of multidrug resistance, and the underlying mechanisms of disinfectants (NaClO and H2O2) on airborne bacteria. The results showed that airborne bacteria were effectively inactivated by atomized NaClO (>160 μg/L) and H2O2 (>320 μg/L) after 15 min. However, some bacteria still survived after disinfection by atomized NaClO (0-80 μg/L) and H2O2 (0-160 μg/L), and they exhibited significant increases in antibiotic resistance. The whole-genome sequencing of the resistant bacteria revealed distinct mutations that were responsible for both antibiotic resistance and virulence. This study also provided evidences and insights into possible mechanisms underlying the induction of antibiotic resistance by air disinfection, which involved intracellular reactive oxygen species formation, oxidative stress responses, alterations in bacterial membranes, activation of efflux pumps, and the thickening of biofilms. The present results also shed light on the role of air disinfection in inducing antibiotic resistance, which could be a crucial factor contributing to the global spread of antibiotic resistance through the air.

Cleaning products: Their chemistry, effects on indoor air quality, and implications for human health

The use of cleaning and disinfecting products both at work and at home increased during the COVID-19 pandemic. Those products often include surfactants, acids/bases, carcinogens such as chloroform, and endocrine-disrupting chemicals, such as cyclosiloxanes, phthalates, and synthetic fragrances, which may cause harmful health effects among professional cleaners as well as among people exposed at home or in their workplaces. The aim of this study was to synthesize the effects of the commonly used chemical, surface cleaning and disinfecting products on indoor air quality, focusing on chemical and particulate matter pollutants, exposure, and human health in residential and public buildings. We also provide a summary of recommendations to avoid harmful exposure and suggest future research directions. PubMed, Google Scholar, Scopus, and Web of Science (WoS) were used to search the literature. Analysis of the literature revealed that the use of cleaning products and disinfectants increase occupants' exposure to a variety of harmful chemical air contaminants and to particulate matter. Occupational exposure to cleaning and disinfectant products has been linked to an increased risk of asthma and rhinitis. Residential exposure to cleaning products has been shown to have an adverse effect on respiratory health, particularly on asthma onset, and on the occurrence of asthma(-like) symptoms among children and adults. Efforts to reduce occupants' exposure to cleaning chemicals will require lowering the content of hazardous substances in cleaning products and improving ventilation during and after cleaning. Experimentally examined, best cleaning practices as well as careful selection of cleaning products can minimize the burden of harmful air pollutant exposure indoors. In addition, indirect ways to reduce exposure include increasing people's awareness of the harmfulness of cleaning chemicals and of safe cleaning practices, as well as clear labelling of cleaning and disinfecting products.

Toxicity and underlying lipidomic alterations generated by a mixture of water disinfection byproducts in human lung cells

Complex mixtures of disinfection by-products (DBPs) are present in disinfected waters, but their mixture toxicity has been rarely described. Apart from ingestion, DBP exposure can occur through inhalation, which may lead to respiratory effects in highly exposed individuals. However, the underlying biological mechanisms have yet to be elucidated. This study aimed to investigate the toxicity of a mixture of 10 DBPs, including haloacetic acids and haloaromatics, on human alveolar A549 cells by assessing their cytotoxicity, genotoxicity, and impact on the cell lipidome. A DBP mixture up to 50 μM slightly reduced cell viability, induced the generation of reactive oxygen species (ROS) up to 3.5-fold, and increased the frequency of micronuclei formation. Exposure to 50 μM DBP mixture led to a significant accumulation of triacylglycerides and a decrease of diacylglycerides and phosphatidylcholines in A549 cells. Lipidomic profiling of extracellular vesicles (EVs) released in the culture medium revealed a marked increase in cholesterol esters, sphingomyelins, and other membrane lipids. Overall, these alterations in the lipidome of cells and EVs may indicate a disruption of lipid homeostasis, and thus, potentially contribute to the respiratory effects associated with DBP exposure.

Non-regulated haloaromatic water disinfection byproducts act as endocrine and lipid disrupters in human placental cells

The disinfection of drinking water generates hundreds of disinfection byproducts (DBPs), including haloaromatic DBPs. These haloaromatic DBPs are suspected to be more toxic than haloaliphatic ones, and they are currently not regulated. This work investigates their toxicity and ability to interfere with estrogen synthesis in human placental JEG-3 cells, and their genotoxic potential in human alveolar A549 cells. Among the haloaromatic DBPs studied, halobenzoquinones (2,6-dichloro-1,4-benzoquinone (DCBQ) and 2,6-dibromo-1,4-benzoquinone (DBBQ)) showed the highest cytotoxicity (EC50: 18-26 μg/mL). They induced the generation of very high levels of reactive oxygen species (ROS) and up-regulated the expression of genes involved in estrogen synthesis (cyp19a1, hsd17b1). Increased ROS was linked to significant depletion of polyunsaturated lipid species from inner cell membranes. The other DBPs tested showed low or no significant cytotoxicity (EC50 ≥ 100 μg/mL), while 2,4,6-trichloro-phenol (TCP), 2,4,6-tribromo-phenol (TBP) and 3,5-dibromo-4-hydroxybenzaldehyde (DCHB) induced the formation of micronuclei at concentrations much higher than those typically found in water (100 μg/mL). This study reveals the different modes of action of haloaromatic DBPs, and highlights the toxic potential of halobenzoquinones, which had a significant impact on the expression of placenta steroid metabolism related genes and induce oxidative stress, implying potential adverse health effects.

Direct generation of DBPs from city dust during chlorine-based disinfection

Chlorine-based disinfectants, such as sodium hypochlorite, are extensively used in our daily lives. In particular, during the recent Covid-19 pandemic and post-pandemic period, excessive amounts of chlorine-based disinfectants were used both indoors and outdoors to interrupt virus transmission. However, the interaction between disinfectants and city dust during the disinfection process has not been sufficiently evaluated. In this study, we conducted a comprehensive investigation into the intrinsic characteristics (e.g. morphology, size, elemental composition, and organic content, etc.) of dust collected from various indoor and outdoor areas. The results showed that the organic carbon content of indoor dust reached 6.14 %, with a corresponding measured dissolved organic carbon value of 4.17 ± 0.23 mg/g (normalized to the dust weight). Concentrations of regulated DBPs, resulting from the interaction between dust and NaClO, ranged from 57.78 ± 2.72 to 102.80 ± 22.63 µg/g for THMs and from 119.18 ± 6.50 to 285.14 ± 36.95 µg/g for HAAs (normalized to the dust weight). More significantly, using non-target analysis through gas chromatography quadrupole time-of-flight mass spectrometry (GC-qTOF-MS), we identified a total of 68, 89, and 87 types of halogenated DBPs from three typical indoor and outdoor sites (R-QH, C-JS, and W-BR, respectively). These unknown DBPs included compounds with higher toxicity compared to regulated DBPs. These findings highlight that city dust is a significant source of DBP generation during chlorine-based disinfection, posing potential harm to both the ecological environment and human health.

Investigation on toxicity and mechanism to Daphnia magna for 14 disinfection by-products: Enzyme activity and molecular docking

Exposure to disinfection by-products (DBPs) has been found to induce a range of toxic effects in aquatic organism. Previous studies have consistently demonstrated that a majority of DBPs have the ability to induce in vivo toxicity in aquatic organisms. However, the impact of DBPs on the metabolic processes of Daphnia magna (D. magna) and the underlying molecular toxicity mechanisms are still not well understood. Therefore, we investigated the effects of 14 DBPs on two oxidative stress enzymes and malondialdehyde (MDA) levels in D. magna. Additionally, we employed molecular docking to simulate the toxicity of DBPs to D. magna at the molecular level. This comprehensive analysis allowed us to gain further insights into the toxicity of DBPs on D. magna. The results showed that among the aliphatic DBPs, the more bromine substituents, the lower the toxicity effect, and it's opposite in the aromatic DBPs. In the detection of oxidative stress level, catalase (CAT) enzyme and superoxide dismutase (SOD) enzyme in D. magna under compound stress showed a low increase and decrease with the increase of concentration. The level of MDA showed a positive correlation with the concentration. In the last, molecular docking simulations have shown promise in predicting the toxicity of DBPs and providing insights into their toxic effects to a certain extent, and the docking situation of P53 is slightly different. Hence, it is imperative to further regulate the presence of aromatic DBPs due to their pronounced toxic effects on D. magna, and these simulations can be complemented with actual experiments to enhance our understanding of the toxicity mechanisms of DBPs.

Occurrence, formation, and proteins perturbation of disinfection byproducts in indoor air resulting from chlorine disinfection

Increased amounts of chlorine disinfectant have been sprayed to inactivate viruses in the environment since the COVID-19 pandemic, and the health risk from chemicals, especially disinfection byproducts (DBPs), has unintentionally increased. In this study, we characterized the occurrence of haloacetic acids (HAAs) and trihalomethanes (THMs) in indoor air and evaluated their formation potential from typical indoor ingredients. Subsequently, the adverse effect of chloroacetic acid on A549 cells was depicted at the proteomic, transcriptional and silico levels. The results revealed that the total concentrations of HAAs and THMs ranged from 1.46 to 4.20 μg/m3 in ten indoor environments. Both classes of DBPs could be generated during the chlorination of prevalent terpenes by competing reactions, which are associated with the volatile state of indoor ingredients after disinfection. The C-type lectin receptor signaling pathway and cellular senescence were significantly perturbed pathways, which interfered with the development of lung fibrosis. The negative effect was further investigated by molecular docking and transcription, which showed that HAAs can interact with four C-type lectin receptor proteins by hydrogen bonds and inhibit the mRNA expression of related proteins. This study highlights the potential secondary biological risk caused by intensive DBPs generated from chlorination and draws our attention to the potential environmental factors leading to chronic respiratory disease.

The occurrence, ecological risk, and control of disinfection by-products from intensified wastewater disinfection during the COVID-19 pandemic

Increased disinfection of wastewater to preserve its microbiological quality during the coronavirus infectious disease-2019 (COVID-19) pandemic have inevitably led to increased production of toxic disinfection by-products (DBPs). However, there is limited information on such DBPs (i.e., trihalomethanes, haloacetic acids, nitrosamines, and haloacetonitriles). This review focused on the upsurge of chlorine-based disinfectants (such as chlorine, chloramine and chlorine dioxide) in wastewater treatment plants (WWTPs) in the global response to COVID-19. The formation and distribution of DBPs in wastewater were then analyzed to understand the impacts of these large-scale usage of disinfectants in WWTPs. In addition, potential ecological risks associated with DBPs derived from wastewater disinfection and its receiving water bodies were summarized. Finally, various approaches for mitigating DBP levels in wastewater and suggestions for further research into the environmental risks of increased wastewater disinfection were provided. Overall, this study presented a comprehensive overview of the formation, distribution, potential ecological risks, and mitigating approaches of DBPs derived from wastewater disinfection that will facilitate appropriate wastewater disinfection techniques selection, potential ecological risk assessment, and removal approaches and regulations consideration.

Traditional methods and biosensors for detecting disinfection by-products in water: A review

In recent years, pollution caused by disinfection by-products (DBPs) has become a global concern. Initially, there were fewer contaminants, and the mechanism of their generation was unclear; however, the number of contaminants has increased exponentially as a result of rapid industrialization and numerous economic activities (e.q., during the outbreak of COVID-19 a surge in the use of chlorinated disinfectants was observed). DBP toxicity results in various adverse health effects and organ failure in humans. In addition, it profoundly affects other forms of life, including animals, plants, and microorganisms. This review comprehensively discusses the pre-treatment methods of traditional and emerging DBPs and the technologies applied for their detection. Additionally, this paper provides a detailed discussion of the principles, applicability, and characteristics of traditional large-scale instrumentation methods (such as gas/liquid/ion chromatography coupled with mass spectrometry) for detecting DBPs based on their respective detection techniques. At the same time, the design, functionality, classification, and characteristics of rapid detection technologies (such as biosensors) are also detailed and analyzed.

Visualizing indoor ozone exposures via o-dianisidine based colorimetric passive sampler

In this study, we developed a colorimetric ozone passive sampler (OPS) incorporating o-dianisidine, a redox dye, into a polydimethylsiloxane sheet. The reaction between ozone (O3) and o-dianisidine result in a visible yellowish color change. Unlike previous passive methods that rely on nitrate extraction or the color disappearance of indigotrisulfonate, the OPS offered improved recognition of average O3 exposure. To optimize OPS based on time-weighted average (TWA), we extracted and quantified the amount of reacted o-dianisidine after exposing OPS to O3 by varying concentrations (0-200 ppb) within 8 h. Colorimetric changes of OPS were further analyzed by capturing images, and the effective absorbance of blue scale showed the best fit (EAB, R2 =0.997). OPS validation on visual detection assessed by six parameters: limit of detection, limit of quantification, reproducibility, sampling rate, selectivity to interfering gases, and sensitivity to environmental factors. To enhance visibility, the OPS was assembled with coloration exposure guidelines, and a smartphone app was developed to quantify average O3 exposures. We further conducted field tests that showed the significant disparity between O3 concentrations and personal O3 exposures, which is considered more crucial for assessing health risks. The OPS was optimized to monitor O3 exposure levels and raise awareness among workers and occupants regarding invisible indoor hazards.

Effects of disinfection by-products in swimming pool environments on the immunological mechanisms of respiratory diseases

Swimming in pools is a popular and healthy recreational activity. However, potential adverse health effects from disinfection byproduct (DBP) exposure in pool water are concerning. This study evaluated how such DBP exposure affects the respiratory system. DBP exposure was simulated with an animal-specific pool environment model. Experimental animals were exposed to DBPs for a specified duration and frequency over 4 weeks. The wet and dry weights of murine lungs were measured, with no significant differences observed. There were no significant differences in interkeukin (IL)-2/4/10, and interferon-γ levels. However, IL-6 expression decreased in the experimental group. To investigate the effects of DBP exposure on immune cell response, various samples, such as bronchoalveolar lavage fluid, lymph nodes, spleen, and thymus, were collected for T-cell isolation and fluorescence-activated cell sorting. Asthma-related blood cell distribution was analyzed using a complete blood count test; no significant differences were found. Thus, DBP exposure through this model did not induce substantial lung tissue damage, major alterations in cytokine expression (besides IL-6), significant immune cell responses, or changes in asthma-associated blood cell distribution. However, considering earlier results, future studies should focus on specific types, intensity, and duration of exercise that could affect DBP exposure-related immune-inflammatory responses.

Development of a non-target strategy for evaluation of potential biological effects of inhalable aerosols generated during purposeful room conditioning using an in vitro inhalation model

OBJECTIVES

An integrated in vitro inhalation approach was outlined to estimate potential adverse acute inhalation effects of aerosols from commercial nebulizer applications used for purposeful room conditioning such as disinfection, scenting or others. Aerosol characterization, exposure estimation and evaluation of acute biological effects by in vitro inhalation were included to generate dose-response data, allowing for determination of in vitro lowest observable adverse effect levels (LOAELs). Correlation of these to estimates of human lung deposition was included for quantitative in vitro to in vivo extrapolation approach (QIVIVE) for acute effects during human exposure.

METHODS

To test the proposed approach, a case study was undertaken using two realistic test materials. An acute in vitro inhalation setup with air-liquid interface A549-cells in an optimized exposure situation (P.R.I.T.® ExpoCube®) was used to expose cells and analysis of relevant biological effects (viability, mitochondrial membrane potential, stress, IL-8 release) was carried out.

RESULTS

The observed dose-responsive effects in a sub-toxic dose-range could be attributed to the main component of one test material and its presence in the aerosol phase of the nebulized material. QIVIVE resulted in a factor of at least 256 between the in vitro LOAEL and the estimated acute human lung exposure for this test material.

CONCLUSIONS

The case-study shows the value of the non-target in vitro inhalation testing approach especially in case of a lack of knowledge on complex product composition. It is expected that approaches like this will be of high value for product safety and environmental health in the future.

Assessment of Residual Chlorine Interaction with Different Microelements in Stormwater Sediments

One consequence of intensive outdoor disinfection using chlorinated compounds is environmental pollution. It has been found that disinfectants are the most effective tool to avoid the spread of infections and viruses. Studies have shown that the use of chlorine-based disinfectants (sodium hypochlorite) leaves residual chlorine and other disinfection byproducts in the environment. They also have harmful effects on, inter alia, water quality, ecosystems, as well as exacerbating the corrosion of surfaces. To meet regulatory standards, monitoring of the presence of residual chlorine in the environment is vitally important. The aim of this study is to analyse the occurrence of residual chlorine in stormwater after outdoor disinfection using sodium hypochlorite and to investigate its interaction with different microelements as well their possible impacts. Stormwater samples collected at permanently disinfected locations were analysed via X-ray absorption spectroscopy. The concentrations of Cl and the following elements Na, Si, K, Ca, Cr, Fe, Ni, Cu, Zn were detected and their relationship with chlorine was determined using the Python programming language. The research presents Cl concentration values (%) that vary from 0.02 to 0.04. The results of the modelling revealed strong correlations between Cl and Fe (value 0.65) and Ca (value -0.61) and the occurrence of CaCl₂ and FeCl₃. The strong relationship between Cl and Fe explains the significant increase in surface corrosion after disinfection with chlorine-based substances.

Exploration of optimal disinfection model based on groundwater risk assessment in disinfection process

Under the influence of different types of disinfectants and disinfection environments, the removal level of pathogens and the formation potential of disinfection by-products (DBPs) will have a dual impact on the groundwater environment. The key points for sustainable groundwater safety management are how to balance the positive and negative relationship and formulate a scientific disinfection model in combination with risk assessment. In this study, the effects of sodium hypochlorite (NaClO) and peracetic acid (PAA) concentrations on pathogenic E. coli and DBPs were investigated using static-batch and dynamic-column experiments, as well as the optimal disinfection model for groundwater risk assessment was explored using quantitative microbial risk assessment and disability-adjusted life years (DALYs) models. Compared to static disinfection, deposition and adsorption were the dominant factors causing E. coli migration at lower NaClO levels of 0-0.25 mg/L under dynamic state, while disinfection was its migration factor at higher NaClO levels of 0.5-6.5 mg/L. In contrast, E. coli removed by PAA was the result of the combined action of deposition, adsorption, and disinfection. The disinfection effects of NaClO and PAA on E. coli differed under dynamic and static conditions. At the same NaClO level, the health risk associated with E. coli in groundwater was higher, whereas, under the same PAA conditions, the health risk was lower. Under dynamic conditions, the optimal disinfectant dosage required for NaClO and PAA to reach the same acceptable risk level was 2 and 0.85 times (irrigation) or 0.92 times (drinking) of static disinfection, respectively. The results may help prevent the misuse of disinfectants and provide theoretical support for managing twin health risks posed by pathogens and DBPs in water treatment.

Composition of Culturable Microorganisms in Dusts Collected from Sport Facilities in Finland during the COVID-19 Pandemic

Sport facilities represent extreme indoor environments due to intense cleaning and disinfection. The aim of this study was to describe the composition of the cultivated microbiota in dust samples collected in sport facilities during the COVID-19 pandemic. A dust sample is defined as the airborne dust sedimented on 0.02 m² within 28 d. The results show that the microbial viable counts in samples of airborne dust (n = 9) collected from seven Finnish sport facilities during the pandemic contained a high proportion of pathogenic filamentous fungi and a low proportion of bacteria. The microbial viable counts were between 14 CFU and 189 CFU per dust sample. In seven samples from sport facilities, 20-85% of the microbial viable counts were fungi. Out of 123 fungal colonies, 47 colonies belonged to the potentially pathogenic sections of Aspergillus (Sections Fumigati, Nigri, and Flavi). Representatives of each section were identified as Aspergillus fumigatus, A. flavus, A. niger and A. tubingensis. Six colonies belonged to the genus Paecilomyces. In six samples of dust, a high proportion (50-100%) of the total fungal viable counts consisted of these potentially pathogenic fungi. A total of 70 isolates were considered less likely to be pathogenic, and were identified as Aspergillus section Nidulantes, Chaetomium cochliodes and Penicillium sp. In the rural (n = 2) and urban (n = 7) control dust samples, the microbial viable counts were >2000 CFU and between 44 CFU and 215 CFU, respectively, and consisted mainly of bacteria. The low proportion of bacteria and the high proportion of stress tolerant, potentially pathogenic fungi in the dust samples from sport facilities may reflect the influence of disinfection on microbial communities.

Resolving the "health vs environment" dilemma with sustainable disinfection during the COVID-19 pandemic

The overuse of disinfection during the COVID-19 pandemic leads to an emerging "health versus environment" dilemma that humans have to face. Irresponsible and unnecessary disinfection should be avoided, while comprehensive evaluation of the health and environmental impacts of different disinfectants is urgently needed. From this discussion, we reach a tentative conclusion that hydrogen peroxide is a green disinfectant. Its on-demand production enables a circular economy model to solve the storage issues. Water, oxygen, and electrons are the only feedstock to generate H2O2. Upon completion of disinfection, H2O2 is rapidly converted back into water and oxygen. This model adopts several principles of green chemistry to ensure overall sustainability along the three stages of its whole life cycle, i.e., production, disinfection, and decomposition. Physical methods, particularly UV irradiation, also provide sustainable disinfection with minimal health and environmental impacts.

Investigation on the effectiveness of ventilation dilution on mitigating COVID-19 patients' secondary airway damage due to exposure to disinfectants

Chlorine-containing disinfectants are widely used in hospitals to prevent hospital-acquired severe acute respiratory syndrome coronavirus 2 infection. Meanwhile, ventilation is a simple but effective means to maintain clean air. It is essential to explore the exposure level and health effects of coronavirus disease 2019 patients' inhalation exposure to by-products of chloride-containing disinfectants under frequent surface disinfection and understand the role of ventilation in mitigating subsequent airway damage. We determined ventilation dilution performance and indoor air quality of two intensive care unit wards of the largest temporary hospital constructed in China, Leishenshan Hospital. The chloride inhalation exposure levels, and health risks indicated by interleukin-6 and D-dimer test results of 32 patients were analysed. The mean ± standard deviation values of the outdoor air change rate in the two intensive care unit wards were 8.8 ± 1.5 h-1 (Intensive care unit 1) and 4.1 ± 1.4 h-1 (Intensive care unit 2). The median carbon dioxide and fine particulate matter concentrations were 480 ppm and 19 μg/m3 for intensive care unit 1, and 567 ppm and 21 μg/m3 for intensive care unit 2, all of which were around the average levels of those in permanent hospitals (579 ppm and 21 μg/m3). Of these patients, the median (lower quartile, upper quartile) chloride exposure time and calculated dose were 26.66 (2.89, 57.21) h and 0.357 (0.008, 1.317) mg, respectively. A statistically significant positive correlation was observed between interleukin-6 and D-dimer concentrations. To conclude, ventilation helped maintain ward air cleanliness and health risks were not observed.

Environmental impacts of the widespread use of chlorine-based disinfectants during the COVID-19 pandemic

Chlorinated disinfectants are widely used in hospitals, COVID-19 quarantine facilities, households, institutes, and public areas to combat the spread of the novel coronavirus as they are effective against viruses on various surfaces. Medical facilities have enhanced their routine disinfection of indoors, premises, and in-house sewage. Besides questioning the efficiency of these compounds in combating coronavirus, the impacts of these excessive disinfection efforts have not been discussed anywhere. The impacts of chlorine-based disinfectants on both environment and human health are reviewed in this paper. Chlorine in molecular and in compound forms is known to pose many health hazards. Hypochlorite addition to soil can increase chlorine/chloride concentration, which can be fatal to plant species if exposed. When chlorine compounds reach the sewer/drainage system and are exposed to aqueous media such as wastewater, many disinfection by-products (DBPs) can be formed depending on the concentrations of natural organic matter, inorganics, and anthropogenic pollutants present. Chlorination of hospital wastewater can also produce toxic drug-derived disinfection by-products. Many DBPs are carcinogenic to humans, and some of them are cytotoxic, genotoxic, and mutagenic. DBPs can be harmful to the flora and fauna of the receiving water body and may have adverse effects on microorganisms and plankton present in these ecosystems.

Ventilation reconstruction in bathrooms for restraining hazardous plume: Mitigate COVID-19 and beyond

Converging evidence reports that the probability of vertical transmission patterns via shared drainage systems, may be responsible for the huge contactless community outbreak in high-rise buildings. Publications indicate that a faulty bathroom exhaust fan system is ineffective in removing lifted hazardous virus-laden aerosols from the toilet bowl space. Common strategies (boosting ventilation capability and applying disinfection tablets) seem unsustainable and remain to date untested. Using combined simulation and experimental approaches, we compared three ventilation schemes in a family bathroom including the traditional ceiling fan, floor fan, and side-wall fan. We found that the traditional ceiling fan was barely functional whereby aerosol particles were not being adequately removed. Conversely, a side-wall fan could function efficiently and an enhanced ventilation capability can have increased performance whereby nearly 80.9% of the lifted aerosol particles were removed. There exists a common, and easily-overlooked mistake in the layout of the bathroom, exposing occupants to a contactless vertical pathogen aerosol transmission route. Corrections and dissemination are thus imperative for the reconstruction of these types of family bathrooms. Our findings provide evidence for the bathroom and smart ventilation system upgrade, promoting indoor public health and human hygiene.

Health effects of sodium hypochlorite: review of published case reports

Sodium hypochlorite is widely used as the main component of cleaners and has an excellent bleaching and sterilizing effect in living and medical environments. In addition to bleaching, it is used for wastewater treatment and for sterilization in food factories, and also for disinfectants during the COVID-19 pandemic. This study analyzed reports of the health effects of sodium hypochlorite and classified them by toxicity along the exposure pathway. Most case reports described the health effects of acute high-concentration exposure, with a common case being dental exposure, mainly during treatment.

Insights into the spatiotemporal occurrence and mixture risk assessment of household and personal care products in the waters from rivers to Laizhou Bay, southern Bohai Sea

Household and personal care products (HPCPs) are a kind of contaminants closely related to daily life, capturing worldwide concern. To our knowledge, this is the first attempt focusing on the spatiotemporal occurrence and mixture risk of HPCPs in the waters from rivers to Laizhou Bay. Nine HPCPs were quantitated in 216 water samples gathered from Laizhou Bay and its adjacent rivers in 2018, 2019, and 2021 to reveal the spatiotemporal occurrence and mixture ecological risks in Laizhou Bay. Eight HPCPs were detected with detection frequencies ranging from 74% to 100%. The total concentrations were in the ranges 105-721 ng L^-1 in river water and 51.3-332 ng L^-1 in seawater. The HPCPs were dominated by p-hydroxybenzoic and triclosan, which together contributed over 75% of the total HPCPs. The average level of the total HPCP concentration in the summer of 2018 (96.1 ng L^-1) was slightly exceed that in the spring of 2019 (91.6 ng L^-1), which is associated with the higher usage of HPCPs and enhanced tourism during summer. However, the highest total concentrations were found in spring of 2021 (124 ng L^-1 in average), which was attribute to a higher level of methylparaben, a predominant paraben used as preservatives in commercial pharmaceuticals of China. Influenced by riverine inputs and ocean currents, higher HPCP concentrations in Laizhou Bay were found nearby the estuary of Yellow River and the southern part of the bay. Triclosan should be given constant concern considering its medium to high risks (RQ > 0.1) in nearly 80% of the water samples. The cumulative risk assessment in two approaches revealed that HPCP mixtures generally elicit medium or high risk to three main aquatic taxa. Considering the worldwide outbreak of COVID-19, the levels and risks of multiple HPCPs in natural waters requires constant attention in future studies.