Recent trend in risk assessment of formaldehyde exposures from indoor air

Mast cells are key mediators in the pulmonary inflammatory response to formaldehyde exposure

Formaldehyde (FA) is a common chemical linked to respiratory problems such as airway hyperresponsiveness and pulmonary inflammation. Due to its toxicological effects and ease of mass production, FA is also recognized as a significant chemical threat by the U.S. Department of Homeland Security. This study investigates the role of mast cells in the pulmonary inflammatory response to acute high-dose FA exposure. Using wild-type (C57BL/6J) and mast cell-deficient (KitW-sh) mouse models, we assessed the impact of oropharyngeal aspiration of FA on lung pathology. Our findings reveal that C57BL/6J mice experienced significant increases in cellular infiltration, altered immune cell populations, and changes in lipid mediator profiles. In contrast, KitW-sh mice exhibited significantly reduced inflammatory responses. Notably, the presence of mast cells was associated with enhanced dendritic cell migration and differential production of bioactive lipid mediators, such as specialized pro-resolving mediators and pro-inflammatory leukotrienes in C57BL/6J mice. These results highlight the crucial role of mast cells in the immune response to FA and suggest they could be therapeutic targets for treating FA-induced lung inflammation.

The Impact of Air Temperature and Pollution on Admissions for Acute Ophthalmic Inflammation at the Emergency Eye Department in Katowice, Poland, from 2011 to 2023

Purpose

To determine if significant correlations occur between recorded values for a) annual temperature, b) air pollution levels, and the prevalence of acute ophthalmic inflammation among patients attending an eye emergency department in an urban setting between 2011 and 2023.

Patients and Methods

A data bank of cases that attended an eye emergency unit (Medical University of Silesia, Katowice, Poland) between 1/1/2011 and 31/12/2023 was accessed. Cases were classified into inflammatory or noninflammatory ophthalmic groups. The former were then subdivided into subgroups for blepharitis, orbital inflammation, lacrimal system inflammation, conjunctivitis, scleritis, keratitis, uveitis with retinitis, endophthalmitis, and optic neuritis. Data on local temperatures and air pollution levels were obtained from available official publications.

Results

Reporting key results (p < 0.05).Total attending the emergency unit increased from 8,172 to 14,261 (8854 during pandemic lockdown in 2020), prevalence of all acute ophthalmic inflammation (y) decreased from 64.70% to 55.40% and prevalence of conjunctivitis within this group decreased from 53.96% to 36.23%.Annual average (±SD) temperature (x, °C) in Silesia increased from 8.33°C (±9.18°) in 2010 to 10.64°C (±6.83°C) in 2020 (paired t-test, p = 0.04). Curvi-linear regression revealed, y = 1.915x3-55.624x2+534.09x-1631.2, (n = 10, r2= 0.489).Prevalence of conjunctivitis was directly correlated with atmospheric concentrations of sulphur dioxide, carbon monoxide and particulate matter in suspended dust with a diameter≤10 microns.After factoring all cases of conjunctivitis, a) prevalence of endophthalmitis, uveitis with retinitis, and scleritis were negatively correlated with temperature, b) atmospheric concentrations of certain pollutants were positively correlated with the prevalence of endophthalmitis, uveitis with retinitis, scleritis and keratitis; and negatively correlated with the prevalence of orbital and lacrimal inflammation, blepharitis, and optic neuritis.

Conclusion

Air pollutants and temperature are linked to the prevalence of certain acute ophthalmic inflammations. Some correlations are negative suggesting some protection against the development of certain conditions. However, negative correlational effects do not necessarily imply negative causal effects.

Formaldehyde and asthma: a plausibility?

Formaldehyde (FA) is a ubiquitous indoor air pollutant emitted from construction, consumer, and combustion-related products, and ozone-initiated reactions with reactive organic volatiles. The derivation of an indoor air quality guideline for FA by World Health Organization in 2010 did not find convincing evidence for bronchoconstriction-related reactions as detrimental lung function. Causal relationship between FA and asthma has since been advocated in meta-analyses of selected observational studies. In this review, findings from controlled human and animal exposure studies of the airways, data of FA retention in the respiratory tract, and observational studies of reported asthma applied in meta-analyses are analyzed together for coherence of direct association between FA and asthma. New information from both human and animal exposure studies are evaluated together with existing literature and assessed across findings from observational studies and associated meta-analyses thereof. Retention of FA in the upper airways is > 90% in agreement with mice exposure studies that only extreme FA concentrations can surpass trachea, travel to the lower airways, and cause mild bronchoconstriction. However, taken together, detrimental lung function effects in controlled human exposure studies have not been observed, even at FA concentrations up 4 ppm (5 mg/m3), and in agreement with controlled mice exposure studies. Typical indoor FA concentrations in public buildings and homes are far below a threshold for sensory irritation in the upper airways, based on controlled human exposure studies, to induce sensory-irritative sensitization nor inflammatory epithelial damage in the airways. Analysis of the observational heterogeneous studies applied in the meta-analyses suffers from several concomitant multifactorial co-exposures, which invalidates a direct association with asthma, thus the outcome of meta-analyses. The evidence of a direct causal relationship between FA and asthma is insufficient from an experimental viewpoint that includes retention data in the upper airways and controlled animal and human exposure studies. Taken together, a coherence of controlled experimental findings with individual observational studies and associated meta-analyses, which suffer from caveats, is absent. Further, lack of identified evidence of FA-IgE sensitization in both experimental studies and observational studies agrees with indoor FA concentrations far below threshold for sensory irritation. The assessment of experimental data with uncontrolled observational studies in meta-analyses is incompatible with a direct causal relationship between FA and asthma or exacerbation thereof due to lack of coherence and plausibility.

A detailed methodology for estimating health-related hazards of workplace exposure to indoor formaldehyde vapours

A comprehensive risk assessment method was applied to examine the risks associated with airborne formaldehyde occupational exposure among hospital laboratory staff. The method assessed exposure levels and health impacts by integrating area and personal air sampling, biological monitoring, and self-reported health data. Samples were collected from 74 workplaces across various departments using NIOSH method 3500 and were analyzed via UV-vis spectrophotometry. The data showed significant differences in exposure levels between departments (p≤0.05) and confirmed the efficacy of the method in identifying risk differences. Despite average personal exposure levels being measured lower than occupational limits, individual assessments indicated that some participants surpassed these limits, emphasizing the necessity of personal monitoring for workers with higher risks. The high prevalence of respiratory symptoms, such as cough and wheezing among staff, indicated the need for further investigation and targeted interventions. Although estimated cancer and non-cancer risks were within safe thresholds, the study emphasized the importance of continuous exposure monitoring and the implementation of effective control measures in hospital laboratory departments with formaldehyde emission. This integrated method improved the reliability and generalizability of formaldehyde exposure risk assessments and aided in the development of safe occupational health practices.•The method integrated personal and area sampling with advanced calibration for precise occupational exposure evaluation in laboratories.•The method used of biomarkers to assess formaldehyde absorption in the body estimating both cancerous and non-cancerous health risks associated with occupational exposure.•Addressed traditional method limitations and integrated risk components to improve data reliability for workplace safety and health risk management.

Construction of a turn-on fluorescent probe for detecting formaldehyde in biological systems and real food samples

The monitoring of formaldehyde (FA) in biosystems and real foods is critical for ensuring human health and food safety. However, the development of effective and highly selective assays for sensing FA in organisms and real food samples remains challenging. Herein, a hydrophilic group-modified the probe (Nap-FA) was reported, which utilizes the specific chemical reaction between FA and hydrazino to trigger a "turn-on" fluorescence response. The probe Nap-FA displayed superior selectivity, high sensitivity, good photostability and a low detection limit in the reaction with FA. Notably, Nap-FA has been successfully used for imaging FA in cells, zebrafish, and plant root tissues. In addition, the rationally constructed probe Nap-FA could rapidly and visually detect FA in real food samples. This work provides a prospective approach for monitoring FA in complex biological systems and food fields.

Residential exposure to air pollution and incidence of leukaemia in the industrial area of Viadana, Northern Italy

BACKGROUND

Exposure to air pollution has been proposed as one of the potential risk factors for leukaemia. Work-related formaldehyde exposure is suspected to cause leukaemia.

METHODS

We conducted a nested register-based case-control study on leukaemia incidence in the Viadana district, an industrial area for particleboard production in Northern Italy. We recruited 115 cases and 496 controls, frequency-matched by age, between 1999 and 2014. We assigned estimated exposures to particulate matter (PM10, PM2.5), nitrogen dioxide (NO2), and formaldehyde at residential addresses, averaged over the susceptibility window 3rd to 10th year prior to the index date. We considered potential confounding by sex, age, nationality, socio-economic status, occupational exposures to benzene and formaldehyde, and prior cancer diagnoses.

RESULTS

There was no association of exposures to PM10, PM2.5, and NO2 with leukaemia incidence. However, an indication of increased risk emerged for formaldehyde, despite wide statistical uncertainty (OR 1.46, 95%CI 0.65-3.25 per IQR-difference of 1.2 μg/m3). Estimated associations for formaldehyde were higher for acute (OR 2.07, 95%CI 0.70-6.12) and myeloid subtypes (OR 1.79, 95%CI 0.64-5.01), and in the 4-km buffer around the industrial facilities (OR 2.78, 95%CI 0.48-16.13), although they remained uncertain.

CONCLUSIONS

This was the first study investigating the link between ambient formaldehyde exposure and leukaemia incidence in the general population. The evidence presented suggests an association, although it remains inconclusive, and a potential significance of emissions related to industrial activities in the district. Further research is warranted in larger populations incorporating data on other potential risk factors.

Human exposure to formaldehyde and health risk assessment: a 46-year systematic literature review

After confirming that formaldehyde (FA) is carcinogenic, many studies were conducted in different countries to investigate this finding. Therefore, according to the dispersion of related studies, a bibliometric review of the current literature was performed with the aim of better understanding the exposure to FA and the resulting health risk, for the first time, using the Scopus database and the two open-source software packages, Bibliometrix R package. After screening the documents in Excel, the data was analyzed based on three aspects including performance analysis, conceptual structure, and intellectual structure, and the results were presented in tables and diagrams. A total of 468 documents were analyzed over period 1977-2023, in which 1956 authors from 56 countries participated. The number of scientific publications has grown significantly from 1977 (n = 1) to 2022 (n = 19). Zhang Y., from the Yale School of Public Health (USA), was identified as the most impactful author in this field. The Science of the Total Environment journal was identified as the main source of articles related to exposure to formaldehyde by publishing 25 studies. The United States and China were the most active countries with the most international collaboration. The main topics investigated during these 46 years included "formaldehyde" and "health risk assessment", which have taken new directions in recent years with the emergence of the keyword "asthma". The present study provides a comprehensive view of the growth and evolution of studies related to formaldehyde and the resulting health risks, which can provide a better understanding of existing research gaps and new and emerging issues.

Effects of N-Acetylcysteine on Humanin and Endostatin in Rats Exposed to Formaldehyde

INTRODUCTION

People are constantly exposed to formaldehyde, a volatile and poisonous gas, in indoor environments. In particular, anatomists, pathologists, histologists, and those involved in embalming are exposed to higher amounts of formaldehyde continuously due to their work. This study aimed to investigate the effect of N-acetylcysteine on endostatin and humanin values in male rats exposed to experimental formaldehyde.

METHODS

In the study, 28 male Spraque-Dawley rats aged 12-14 weeks (seven animals in each group: control group, formaldehyde group, N-acetylcysteine group, formaldehyde+N-acetylcysteine group) were used. Four weeks later, the animals were sacrificed by decapitation. Following decapitation, endostatin and humanin levels in the serum of rats were studied by the enzyme-linked immunoassay (ELISA) method. In all analyses, p<0.05 was accepted as statistically significant.

RESULTS

Humanin and endostatin values were checked in the serum of rats. When humanin levels were compared between groups, a statistically significant difference was found between the formaldehyde group and both the control group (p<0.05) and the N-acetylcysteine group (p<0.05). In the formaldehyde+N-acetylcysteine group, it was determined that the humanin level was impaired due to formaldehyde exposure, approaching the control group values with the administered N-acetylcysteine. When the endostatin level was compared between the groups, a statistical significance (p<0.05) was found only between the formaldehyde group and the N-acetylcysteine group. In the formaldehyde+N-acetylcysteine group, it was determined that the endostatin level was impaired due to formaldehyde exposure, approaching the control group values with the administered N-acetylcysteine.

CONCLUSION

In this study, the effects of N-acetylcysteine on humanin and endostatin on rats exposed to formaldehyde were demonstrated for the first time. Formaldehyde exposure negatively affected humanin and endostatin levels in rat sera. N-acetylcysteine ameliorated the negative effects of formaldehyde, bringing humanin and endostatin levels closer to the healthy control group.

The impact of formaldehyde exposure on lung inflammatory disorders: Insights into asthma, bronchitis, and pulmonary fibrosis

Lung inflammatory disorders are a major global health burden, impacting millions of people and raising rates of morbidity and death across many demographic groups. An industrial chemical and common environmental contaminant, formaldehyde (FA) presents serious health concerns to the respiratory system, including the onset and aggravation of lung inflammatory disorders. Epidemiological studies have shown significant associations between FA exposure levels and the incidence and severity of several respiratory diseases. FA causes inflammation in the respiratory tract via immunological activation, oxidative stress, and airway remodelling, aggravating pre-existing pulmonary inflammation and compromising lung function. Additionally, FA functions as a respiratory sensitizer, causing allergic responses and hypersensitivity pneumonitis in sensitive people. Understanding the complicated processes behind formaldehyde-induced lung inflammation is critical for directing targeted strategies aimed at minimizing environmental exposures and alleviating the burden of formaldehyde-related lung illnesses on global respiratory health. This abstract explores the intricate relationship between FA exposure and lung inflammatory diseases, including asthma, bronchitis, allergic inflammation, lung injury and pulmonary fibrosis.

The Impact of Air Pollution on Asthma Severity among Residents Living near the Main Industrial Complex in Oman: A Cross-Sectional Study

BACKGROUND

Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North.

METHODS

The state health clinics' records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from the SIP, Majan Industerial Area (MIA), and Sohar Industerial Zone (SIZ) to determine high-, intermediate-, and low-exposure zones (<6 km, 6-12 km and >12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined.

RESULTS

The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01-5.78), (RR:1.91; CI95%: 1.01-3.6), and (RR:1.68; CI95%: 0.92-3.09) for SIP, MIP, and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N 69 and N 72) and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19-7.45 and RR:2.55; CI95%: 1.00-6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25-50 age group (RR:2.05; CI95%: 1.26-3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminants (dust and smoke) also increased the risk of severe asthma symptoms, but their effects were less important in the high-risk zone, suggesting much more important risk factors. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to SIP as the most influential predictor.

CONCLUSIONS

This study highlights the high asthma burden near SIP, linked to port proximity, smoking, and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Role and mechanism of miR-871-3p/Megf8 in regulating formaldehyde-induced cardiomyocyte inflammation and congenital heart disease

OBJECTIVE AND DESIGN

We aimed to investigate the molecular mechanism underlying formaldehyde (FA)-induced congenital heart disease (CHD) using in vitro and in vivo models.

MATERIALS AND SUBJECTS

Neonatal rat heart tissues and H9C2 cells were used for in vitro studies, while FA-exposed new-born rats were used for in vivo studies.

TREATMENT

H9C2 cells were exposed to FA concentrations of 0, 50, 100 and 150 μM/mL for 24 h.

METHODS

Whole transcriptome gene sequencing identified differentially expressed miRNAs in neonatal rat heart tissues, while Real-time quantitative PCR (RT-qPCR) assessed miR-871-3p and Megf8 expression. RNA pull-down and dual-luciferase reporter assays determined miR-871-3p and Megf8 relationships. Inflammatory cytokine expression was assessed by western blotting. A FA-induced CHD model was used to validate miR-871-3p regulatory effects in vivo.

RESULTS

We identified 89 differentially expressed miRNAs, with 28 up-regulated and 61 down-regulated (fold change ≥ 2.0, P < 0.05). Inflammation (interleukin) and signalling pathways were found to control FA-induced cardiac dysplasia. miR-871-3p was upregulated in FA-exposed heart tissues, modulated inflammation, and directly targeted Megf8. In vivo experiments showed miR-871-3p knockdown inhibited FA-induced inflammation and CHD.

CONCLUSION

We demonstrated miR-871-3p's role in FA-induced CHD by targeting Megf8, providing potential targets for CHD intervention and improved diagnosis and treatment strategies.

A measurement and modelling investigation of the indoor air chemistry following cooking activities

Domestic cooking is a source of indoor air pollutants, including volatile organic compounds (VOCs), which can impact on indoor air quality. However, the real-time VOC emissions from cooking are not well characterised, and similarly, the resulting secondary chemistry is poorly understood. Here, selected-ion flow-tube mass spectrometry (SIFT-MS) was used to monitor the real-time VOC emissions during the cooking of a scripted chicken and vegetable stir-fry meal, in a room scale, semi-realistic environment. The VOC emissions were dominated by alcohols (70% of total emission), but also contained a range of aldehydes (14%) and terpenes (5%), largely attributable to the heating of oil and the preparation and heating of spices, respectively. The direct cooking-related VOC emissions were then simulated using the Indoor Chemical Model in Python (INCHEM-Py), to investigate the resulting secondary chemistry. Modelling revealed that VOC concentrations were dominated by direct emissions, with only a small contribution from secondary products, though the secondary species were longer lived than the directly emitted species. Following cooking, hydroxyl radical concentrations reduced by 86%, while organic peroxy radical levels increased by over 700%, later forming secondary organic nitrates, peroxyacylnitrates (PANs) and formaldehyde. Monoterpene emissions were shown to drive the formation of secondary formaldehyde, albeit to produce relatively modest concentrations (average of 60 ppt). Sensitivity analysis of the simulation conditions revealed that increasing the outdoor concentrations of ozone and NOx species (2.9× and 9×, respectively) resulted in the greatest increase in secondary product formation indoors (≈400%, 200% and 600% increase in organic nitrates, PANs and formaldehyde production, respectively). Given the fact that climate change is likely to result in increased ozone concentrations in the future, and that increased window-opening in response to rising temperatures is also likely, higher concentrations of indoor oxidants are likely in homes in the future. This work, therefore, suggests that cooking could be a more important source of secondary pollutants indoors in the future.

Inhalational exposure to formaldehyde, carcinogenic, and non-carcinogenic risk assessment: A systematic review

Formaldehyde is one of the most widely used substances in a variety of industries, although it was classified as a human carcinogen by the International Agency for Research on Cancer (IARC). The present systematic review was conducted to retrieve studies related to occupational exposure to formaldehyde until November 2, 2022. Aims of the study were to identify workplaces exposed to formaldehyde, to investigate the formaldehyde concentrations in various occupations and to evaluate carcinogenic and non-carcinogenic risks caused by respiratory exposure to this chemical among workers. A systematic search was done in Scopus, PubMed and Web of Science databases to find the studies done in this field. In this review, studies that did not meet the criteria specified by Population, Exposure, Comparator, and Outcomes (PECO) approach were excluded. In addition, the inclusion of studies dealing with the biological monitoring of FA in the body and review studies, conference articles, books, and letters to the editors were avoided. The quality of the selected studies was also evaluated using the Joanna Briggs Institute (JBI) checklist for analytic-cross-sectional studies. Finally, 828 studies were found, and after the investigations, 35 articles were included in this study. The results revealed that the highest formaldehyde concentrations were observed in waterpipe cafes (1,620,000 μg/m³) and anatomy and pathology laboratories (4237.5 μg/m³). Carcinogenic and non-carcinogenic risk indicated the potential health effects for employees due to respiratory exposure as acceptable levels of CR = 1.00 × 10^-4 and HQ = 1, respectively were reported to be exceeded in more than 71% and 28.57% of the investigated studies. Therefore, according to the confirmation of formaldehyde's adverse health effects, it is necessary to adopt targeted strategies to reduce or eliminate exposure to this compound from the occupational usage.

Self-Luminous Wood Coatings with Carbon Dots/TiO2 Grafted Afterglow SrAl2O4: Eu, Dy Core-Shell Phosphors for Long-Lasting Formaldehyde Removal

Long-term relief of indoor volatile pollution has become a competitive issue worldwide in both visible and dark environments. A novel self-luminous wood coating with carbon dots (CDs)/titanium dioxide (TiO₂) nanomaterial coated SrAl₂O₄: Eu²⁺, Dy³⁺ (CDs/TiO₂@SAO) composite was prepared for the long-term degradation of formaldehyde through a simple sol-gel method. The microstructure, chemical composition, ultraviolet-visible (UV-vis) spectra, and long-lasting fluorescence of the CDs/TiO₂@SAO photocatalyst were analyzed to illustrate the mechanism for degrading formaldehyde. The obtained CDs with a particle size of ~2-7 nm have a good graphite structure and presented good absorption in visible light. In addition, owing to the synergistic effect of the CDs/TiO₂ nanomaterial coating layer and the long-afterglow luminescence of the SAO phosphor, the CDs/TiO₂@SAO composite can absorb a part of the visible light for photocatalytic degradation and store luminous energy efficiently at daytime so as to give out visible luminescence continuously for a few hours in the darkness. Furthermore, the functional wood coatings with CDs/TiO₂@SAO composite presented continuous and efficient photocatalytic activity in the presence and absence of light exposure. The current research could provide a new strategy for designing an efficient photocatalyst for degrading formaldehyde pollution in the daytime with a visible light supply and in an indoor dark environment without an external light source.

Relationship between formaldehyde exposure, respiratory irritant effects and cancers: a review of reviews

OBJECTIVES

Formaldehyde is an organic compound used in the production of resins, paper, wood plywood, solvents and cleaning products. Formaldehyde is also present when tobacco is smoked. Formaldehyde has been defined as an irritant and is classified as a human carcinogen by the International Agency for Research on Cancer. The purpose of this study was to demonstrate the following two distinct correlations: (1) the association between formaldehyde exposure and development of irritant diseases affecting the respiratory tract, mainly asthma; and (2) the association between formaldehyde exposure and development of neoplastic diseases.

STUDY DESIGN

This was an umbrella review.

METHODS

A search was conducted in the three main electronic databases of scientific literature: PubMed, Scopus and Web of Science. The search included systematic reviews and meta-analyses published in the previous 10 years. Initially, titles and abstracts of retrieved articles were evaluated, then full-text assessments of selected articles took place. Data extraction and quality assessment were performed according to Assessing the Methodological Quality of Systematic Reviews (AMSTAR) score.

RESULTS

A total of 630 articles were initially collected. Nine articles concerning the association between formaldehyde exposure and asthma were included in the present review, and the majority of these reported good association. In addition, 27 articles investigating the association between formaldehyde exposure and neoplastic diseases were included in the review. These studies showed that nasopharyngeal cancer and leukaemia were the most represented neoplastic diseases; however, only a weak association was reported between formaldehyde exposure and cancer.

CONCLUSIONS

Although the studies included in this review did not show a strong association between exposure to formaldehyde and irritant or neoplastic diseases, the World Health Organisation recommends that levels of formaldehyde do not exceed the threshold value of 0.1 mg/m³ (0.08 ppm) for a period of 30 min. It is recommended that preventive measures, such as ventilation in workplaces with high exposure to formaldehyde and environmental monitoring of formaldehyde concentrations, are implemented.

Shape memory luminescent cellulose/chitosan hydrogel for high sensitive detection of formaldehyde

Hybrid hydrogels containing biomacromolecules have been widely used in sensors, fluorescent probes, and other fields due to their high biocompatibility and nontoxicity. In this paper, tough hydrogels with interconnected macro-pores have been fabricated by freeze-induced chemical cross-linking of microfibrillated cellulose (MFC) and organic modified chitosan (CS). In this hydrogel materials, three-dimensional networks were formed by abundant hydrogen bonds and chemical cross-linking. Luminescent lanthanide complexes were covalently bonded to the hydrogel networks through coordination of Eu³⁺ ions with 2, 3-pyridine dicarboxylic acid modified chitosan. The luminescence of hydrogel materials was further improved by the replacement of coordination water with 2-thiophenyltrifluoroacetone (TTA). The prepared hydrogels showed excellent shape memory properties both under water and in air. The stress of the hybrid hydrogel at 80 % strain can reach 159 kPa, which is much higher than that of the traditional microfibrillated cellulose-based hydrogels. The obtained luminescent hybrid hydrogels exhibited an excellent fluorescence detection effect on formaldehyde. The detection limit for formaldehyde is 45.7 ppb, which is much lower than the WHO standard (80 ppb for indoor air). The novel, facile preparing procedure may extend the potential applications of hybrid lanthanide luminescent hydrogel as fluorescence probes for pollution monitoring, especially for formaldehyde and other organic aldehydes.

Occupational health risk assessment of airborne formaldehyde in medical laboratories

The professional use of formaldehyde is a major occupational health concern in medical laboratory operations. Quantification of various risks associated with chronic exposure to formaldehyde may help in understanding the related hazards. This study designed to assess the health risks associated with inhalation exposure to formaldehyde involving biological, cancer, and non-cancer risks in medical laboratories. This study was performed in the hospital laboratories at Semnan Medical Sciences University. Risk assessment was performed in pathology, bacteriology, hematology, biochemistry, and serology laboratories with 30 employees, using formaldehyde in their daily routine operations. We determined area and personal exposures to airborne contaminant, applied standard air sampling, and analytical method recommended by National Institute of Occupational Safety and Health (NIOSH). We addressed formaldehyde-specific hazard by estimating peak blood level, life cancer risk, and the hazard quotient of non-cancer risks, adapted from Environmental Protection Agency (EPA) assessment method. The airborne formaldehyde concentrations in the laboratory personal samples ranged 0.0156-0.5940 ppm (mean = 0.195 ppm, SD = 0.048) and area exposure ranged 0.0285-1.0810 ppm (mean = 0.462 ppm, SD = 0.087). Based on workplace exposure, peak blood levels of formaldehyde were estimated at minimum 0.0026 mg/l to maximum 0.152 mg/l (mean = 0.015 mg/l, SD = 0.016). The mean cancer risk levels in terms of area and personal exposures were estimated respectively at 3.93 E - 8 μg/m³ and 1.84 E - 4 μg/m³, and for the non-cancer risk levels of the same exposures measured respectively at 0.03 μg/m³ and 0.07 μg/m³. Formaldehyde levels were significantly higher among laboratory employees, especially bacteriology workers. Exposure and risk could be minimized by strengthening control measures including the use of management controls, engineering controls, and respiratory protection equipment to reduce exposure levels of all workers to less than the allowed exposure limits and improve indoor air quality in the workplace.

Online Volatile Compound Emissions Analysis Using a Microchamber/Thermal Extractor Coupled to Proton Transfer Reaction-Mass Spectrometry

Indoor air is a complex and dynamic mixture comprising manifold volatile organic compounds (VOCs) that may cause physiological and/or psychological discomfort, depending on the nature of exposure. This technical note presents a novel approach to analyze VOC emissions by coupling a microchamber/thermal extractor (μ-CTE) system to a proton transfer reaction-mass spectrometer (PTR-MS). This configuration provides an alternative to conventional emissions testing of small objects. The dynamic emission profiles of VOCs from a representative 3D-printed model are presented as a proof-of-concept analysis. Emission profiles are related to the target compound volatility, whereby 2-propanol and acetaldehyde exhibited the highest emissions and most rapid changes compared to the less volatile vinyl crotonate, 2-hydroxymethyl methacrylate, and mesitaldehyde, which were present at lower concentrations and showed different dynamics. Comparative measurements of the emission profiles of these compounds either with or without prior static equilibration yielded stark differences in their dynamics, albeit converging to similar values after 15 min of sampling time. Further, the utility of this system to determine the time required to capture a specific proportion of volatile emissions over the sampling period was demonstrated, with a mean duration of 8.4 ± 0.3 min to sample 50% of emissions across all compounds. This novel configuration provides a means to characterize the dynamic nature of VOC emissions from small objects and is especially suited to measuring highly volatile compounds, which can present a challenge for conventional sampling and analysis approaches. Further, it represents an opportunity for rapid, targeted emissions analyses of products to screen for potentially harmful volatiles.

Effects of airflow rate and plant species on formaldehyde removal by active green walls

Formaldehyde is a hazardous volatile organic compound (VOC) listed as a Group 1 carcinogen by the International Agency for Research on Cancer. The active green wall system is a promising technology that utilizes active airflow passing through plants grown along a vertical alignment to increase their mass exposure to pollutants. However, few studies have investigated the effect of airflow rate on their efficacy for formaldehyde removal, and plant-mediated effects are unknown. This study assessed the formaldehyde removal ability of the active green wall using dynamic experiments. Three levels of airflow rate (30, 50, and 65 m³·h^-1) and inlet formaldehyde concentration (1.0, 2.0, and 3.5 mg·m^-3) were used and three plant species were investigated. The removal of formaldehyde by active green walls was significantly (P < 0.01) affected by the airflow rate, formaldehyde concentration, and plant species. The single pass removal efficiency varying from 38.18 to 94.42% decreased as the airflow rate and formaldehyde concentration increased. The elimination capacity varied from 189 to 1154 mg·m^-2·h^-1 and increased with the inlet formaldehyde loading rate. Significant differences in formaldehyde removal effectiveness among the plant species were observed with Chlorophytum comosum performing the best, followed by Schefflera octophylla, with Chamaedorea elegans being the worst.

Emission characteristics of formaldehyde from natural gas combustion and effects of hood exhaust in Chinese kitchens

Formaldehyde (HCHO) is a well known carcinogen. While most studies investigate emission from wood-based materials, knowledge about releasing of HCHO by natural gas combustion is quite limited. This study conducted field measurements in 9 households to address this issue. We found that emission factor is mainly in the range of 50-200 mg_HCHO/m³_natural gas (median value is 85 mg/m³). Emission rate mainly falls into a range of 0.1-0.4 mg_HCHO/min (median value is 0.16 mg/min). It is also revealed that as the natural gas flow rate increases, the emission factor decreases with a statistically significant Spearman correlation coefficient of -0.46 (p < 0.05). The emission rate shows an opposite trend with a Spearman correlation coefficient of 0.48 (p < 0.05). Formaldehyde generated by natural gas combustion in kitchens can quickly disperse to an adjacent living room when kitchen door is open. A range hood can effectively remove formaldehyde in kitchens if kitchen window is open and kitchen door is closed. Its performance would decrease by half otherwise. These results imply a health co-benefit of reducing household usage of carbon-based natural gas in the age of carbon neutrality aiming climate change.

Evaluation of formaldehyde exposure among gross dissection after modified embalming solution and health assessment

Mainly embalming fixative contains formaldehyde which is classified as a carcinogen. People who work with cadavers have been at higher risk of cancer after formaldehyde exposure. We have formulated a less-formalin fixative (contained 3.6% formaldehyde,23.8% ethanol, 15% glycerin, and 0.2% phenol in the water) for preserving cadavers. Therefore, the objective of the present study was to evaluate the level of atmospheric formaldehyde indoors and the breathing exposure of medical students during dissection classes. We also analyzed the pulmonary parameters and effects of formaldehyde. The levels of atmospheric formaldehyde indoors and personal breathing exposure were sampled during anatomy dissection classes (musculoskeletal system, respiratory system, and abdominopelvic organ system) using sorbent tubes with air sampling pumps. Samples were then analyzed using Gas Chromatography with Flame Ionization Detector (GC-FID). The mean level of formaldehyde indoor air among the three classes was 0.518 ± 0.156 ppm whereas the formaldehyde level in the personal breathing zone was 0.956±0.408 ppm, which exceeded the recommended exposure standards of international agencies, including NIOSH agency and PEL of Thailand legislation. The laboratory had high humidity, high room temperature, and poor air ventilation. There was a significant difference in FVC, FEV1, and PEF (p < 0.05) between the sexes of students. Comparison pulmonary parameters between students and instructors showed that all parameters of the pulmonary function test had no significant differences. General fatigue and burnings of eyes and nose associated with strong odor were the most common symptoms reported during the dissection classes. The modified embalming fixative was used less formalin with ethanol-glycerin mixture, and it was suitable for the study of medical students, with few side effects of respiratory problems. However, the modified exhaust ventilation with local table-exhaust ventilation and heating-ventilation-air conditioning system performance were urgent issues for reducing levels of formaldehyde indoor air in the dissection room.

Seasonal and diurnal patterns of outdoor formaldehyde and impacts on indoor environments and health

Formaldehyde is concerned as an important indoor carcinogen. While contribution of outdoor formaldehyde to indoor concentration is recognized, long-term measurement about its impact on indoor environments remain missing. We measured both outdoor and indoor formaldehyde concentrations for over one year in Nanjing (east-central China) and calculated the outdoor/indoor (O/I) ratios. 64.8% of the measured outdoor concentration have exceeded the chronic reference exposure criteria of 0.009 mg/m³ set by Office of Environmental Health Hazard Assessment (OEHHA). The outdoor concentration was highest in summer with median value of 0.020 mg/m³ and lowest in spring with median value of 0.009 mg/m³. Diurnally, outdoor formaldehyde concentration was highest at noon with median value of 0.013 mg/m³ and lowest at night with median value of 0.01 mg/m³. Health analysis revealed that cancer risk by exposure to this concentration level is 1.6 × 10^-4, higher than threshold limit of 10^-6. In addition, the median O/I ratios are 0.18 and 0.27 in two offices, indicating that outdoor formaldehyde contributes to indoor concentrations by about one quarter. The change of O/I ratio also shows a similar seasonal and diurnal trend as outdoor concentrations (highest in the summer in a year and at noon in a day). Outdoor formaldehyde concentration is therefore not negligible as a contributor to indoor concentration, especially as indoor concentration limit gets continuously lowered. This factor should be taken into account in indoor air quality design and maintenance.

Modification of cleaning product formulations could improve indoor air quality

Cleaning products contain numerous individual chemicals, which can be liberated on use. These species can react in air to form new chemical species, some of which are harmful to health. This paper uses a detailed chemical model for indoor air chemistry, to understand the chemical reactions that can occur following cleaning, assuming cleaning products with different proportions of limonene, α-pinene, and β-pinene are used. The tests included the pure compounds, 50:50 mixtures and mixtures in proportion to the rates of reaction with ozone and the hydroxyl radical. For the 3 h following cleaning, pure α-pinene was most efficient at producing particles, pure limonene for nitrated organic material, and a 50:50 mixture of β-pinene and limonene for formaldehyde, leading to enhancements of 1.1 μg/m³ , 400 ppt, and 1.8 ppb, respectively, compared to no cleaning. Cleaning in the afternoon enhanced concentrations of secondary pollutants for all the mixtures, owing to higher outdoor and hence indoor ozone compared to the morning. These enhancements in concentrations lasted several hours, despite the cleaning emissions only lasting for 10 min. Doubling the air exchange rate enhanced concentrations of formaldehyde and particulate matter by ~15% while reducing that of nitrated organic material by 13%. Changing product formulations has the potential to change the resulting indoor air quality and consequently, impacts on health.

Evaluating the Sub-Acute Toxicity of Formaldehyde Fumes in an In Vitro Human Airway Epithelial Tissue Model

Formaldehyde (FA) is an irritating, highly reactive aldehyde that is widely regarded as an asthmagen. In addition to its use in industrial applications and being a product of combustion reaction and endogenous metabolism, FDA-regulated products may contain FA or release FA fumes that present toxicity risks for both patients and healthcare workers. Exposure to airborne FA is associated with nasal neoplastic lesions in both animals and humans. It is classified as a Group 1 carcinogen by International Agency for Research on Cancer (IARC) based on the increased incidence of cancer in animals and a known human carcinogen in the Report on Carcinogens by National Toxicology Program (NTP). Herein, we systematically evaluated the tissue responses to FA fumes in an in vitro human air-liquid-interface (ALI) airway tissue model. Cultures were exposed at the air interface to 7.5, 15, and 30 ppm of FA fumes 4 h per day for 5 consecutive days. Exposure to 30 ppm of FA induced sustained oxidative stress, along with functional changes in ciliated and goblet cells as well as possible squamous differentiation. Furthermore, secretion of the proinflammatory cytokines, IL-1β, IL-2, IL-8, GM-CSF, TNF-a and IFN-γ, was induced by repeated exposures to FA fumes. Expression of MMP-1, MMP-3, MMP-7, MMP-10, MMP-12, and MMP-13 was downregulated at the end of the 5-day exposure. Although DNA-damage was not detected by the comet assay, FA exposures downregulated the DNA repair enzymes MGMT and FANCD2, suggesting its possible interference in the DNA repair capacity. Overall, a general concordance was observed between our in vitro responses to FA fume exposures and the reported in vivo toxicity of FA. Our findings provide further evidence supporting the application of the ALI airway system as a potential in vitro alternative for screening and evaluating the respiratory toxicity of inhaled substances.

miR-153-3p Targets βII Spectrin to Regulate Formaldehyde-Induced Cardiomyocyte Apoptosis

Background: Formaldehyde (FA) is ubiquitous in the environment and can be transferred to the fetus through placental circulation, causing miscarriage and congenital heart disease (CHD). Studies have shown that βII spectrin is necessary for cardiomyocyte survival and differentiation, and its loss leads to heart development defects and cardiomyocyte apoptosis. Additionally, previous studies have demonstrated that miRNA is essential in heart development and remodeling. However, whether miRNA regulates FA-induced CHD and cardiomyocyte apoptosis remains unclear. Methods: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Real-time quantitative PCR (RT-qPCR) and Western blot were performed to examine the level of miR-153-3p, βII spectrin, caspase 7, cleaved caspase7, Bax, Bcl-2 expression in embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis. Apoptotic cell populations were evaluated by flow cytometry and Tunel. Luciferase activity assay and RNA pull-down assay were used to detect the interaction between miR-153-3p and βII spectrin. Masson's trichrome staining detects the degree of tissue fibrosis. Fluorescence in situ hybridization (FISH) and Immunohistochemistry were used to detect the expression of miR-153-3p and βII spectrin in tissues. Results: Using commercially available rat embryonic cardiomyocytes and a rat model of fetal cardiomyocyte apoptosis, our studies indicate that miR-153-3p plays a regulatory role by directly targeting βII spectrin to promote cardiomyocyte apoptosis. miR-153-3p mainly regulates cardiomyocyte apoptosis by regulating the expression of caspase7, further elucidating the importance of apoptosis in heart development. Finally, the results with our animal model revealed that targeting the miR-153-3p/βII spectrin pathway effectively regulated FA-induced damage during heart development. Recovery experiments with miR-153-3p antagomir resulted in the reversal of FA-induced cardiomyocyte apoptosis and fetal cardiac fibrosis. Conclusion: This study investigated the molecular mechanism underpinning the role of βII spectrin in FA-induced CHD and the associated upstream miRNA pathway. The study findings suggest that miR-153-3p may provide a potential target for the clinical diagnosis and treatment of CHD.

Formaldehyde, aliphatic aldehydes (C2 -C11 ), furfural, and benzaldehyde in the residential indoor air of children and adolescents during the German Environmental Survey 2014-2017 (GerES V)

Indoor air concentrations of formaldehyde, furfural, benzaldehyde, and 11 aliphatic aldehydes (C₂ -C₁₁ ) were measured in residences of 639 participants in the German Environmental Survey for Children and Adolescents 2014-2017 (GerES V). Sampling was conducted using passive samplers over periods of approximately seven days for each participant. The most abundant compounds were formaldehyde and hexanal with median concentrations of 24.9 µg m^-3 and 10.9 µg m^-3 , respectively. Formaldehyde concentrations exceeded the Guide Value I recommended by the German Committee on Indoor Guide Values (Ausschuss für Innenraumrichtwerte - AIR) (0.10 mg m^-3 ) for 0.3% of the participating residences. The sum of aliphatic n-aldehydes between C₄ (butanal) and C₁₁ (undecanal) exceeded their Guide Value (0.10 mg m^-3 ) for 2.0% of the residences. The geometric mean concentrations of most aldehydes were lower than in the earlier GerES IV (2003-2006) study. Formaldehyde and hexanal concentrations, however, were comparable in both studies and showed no significant difference. Indoor aldehyde concentrations did not exhibit significant correlations with factors collected in questionnaires, such as the age of the participants, their socio-economic status, the location of the residence (former East/West Germany), migration background, tobacco exposure, and the type of furniture used. The validity of the passive sampler measurements was verified against active sampling techniques in a test chamber experiment.

Is micronucleus assay in oral exfoliated cells a suitable tool for biomonitoring children exposed to environmental pollutants? A systematic review

The aim of this review was to evaluate if micronucleus assay in oral exfoliated cells is a suitable tool for biomonitoring children exposed to environmental pollutants. Through the electronic databases PubMed/Medline, Scopus, and Web of Science, all published studies until April 2021 that examined the relationship between exposure to environmental pollutants and micronucleus frequency in oral cells were searched. All relevant articles using a combination of the following keywords-"children," "micronucleus," "oral cells," and "environmental pollution"-were considered. A total of 20 papers met the criteria for inclusion in the systematic review. The results regarding the cytogenetic damage induced by environmental pollutants are conflicting. Some authors have demonstrated that environmental pollution induces mutagenesis in oral cells while others did not. Following the parameters of the Project for Effective Public Health Practices (EPHPP) and after extensive reading of all the articles included, a total of 12 articles had moderate and strong scores and 8 had a classification considered weak. Taken together, this review was able to demonstrate the association between micronucleus frequency and exposure to environmental pollutants in oral exfoliated cells of children.

Associations between prenatal exposure to volatile organic compounds and neurodevelopment in 12-month-old children: The Japan Environment and Children's Study (JECS)

In recent years, there has been an increase in the number of problems associated with neurodevelopmental disorders in children, and there has been a growing interest in the relationship between environmental chemicals and children's health. The objective of this study was to examine whether an association exists between occupational or environmental prenatal maternal exposure to volatile organic compounds and the risk of neurodevelopmental disorders in children using Japanese translations of the Ages & Stages Questionnaires, Third Edition (J-ASQ-3). An increase in the risk of neurodevelopmental delay in 12-month-old children associated with maternal exposure to formalin or formaldehyde was identified in terms of problem-solving (odds ratio (OR): 1.76, 95% confidence interval (CI): 0.99-3.12) and personal-social skills (OR: 3.32, 95% CI: 1.46-7.55). It is not clear whether or not this tendency is reversible, and whether it is observed past 12 months of age. Further research and a preventive approach are needed.

Circular RNA-CDR1as is involved in lung injury induced by long-term formaldehyde inhalation

OBJECTIVE

Formaldehyde (FA) is known to induce lung injury, but the underlying molecular mechanism remains largely unclear. CDR1as is an important member of the circular RNAs (circRNAs) family and functions as miRNA sponges with gene-regulatory potential. Our earlier circRNA microarray data showed CDR1as was highly expressed in lung tissue exposed to FA. However, the mechanism of circRNA-CDR1as mediates the FA-exposed lung injury is still unclear. This study aimed to explore the role of CDR1as in lung injury.

MATERIALS AND METHODS

In this study, FA was inhaled at doses of 0.5, 2.46, and 5 mg/m3, respectively. After exposure 8 weeks, lung histopathological examination, lung injury score, and IL-1β in bronchoalveolar lavage fluid (BALF) were determined. The expressions of CDR1as, rno-miR-7b and Atg7 were detected and the potential interaction of circRNA/miRNA/mRNA was predicted by bioinformatics analysis, including drawing circRNA/miRNA/mRNA interaction network, GO and KEGG analysis.

RESULTS

Our results indicated FA inhalation upregulated the expression of CDR1as in lung tissues in a dose-dependent manner while the expression of rno-miR-7b decreased and Atg7 increased. Moreover, the alteration of CDR1as was positively correlated with lung injury.

DISCUSSION AND CONCLUSIONS

CircRNA/miRNA/mRNA prediction further explained the possible effect mechanisms of CDR1as. These data implicated that CDR1as might be a critical regulator involved in lung injury induced by FA.

Effect of formaldehyde exposure on bacterial communities in simulating indoor environments

Indoor formaldehyde (CH₂O) exceeding the recommended level is a severe threat to human health. Few studies have investigated its effect on indoor surface bacterial communities, affecting habitants' health. This study used 20-L glass containers to mimic the indoor environment with bacterial inputs from human oral respiration. The behavior of bacterial communities responding to CH₂O varied among the different CH₂O levels. The bacterial community structure significantly changed over time in the 0.054 mg·m^-3 CH₂O group, which varied from the 0.1 mg·m^-3 and 0.25 mg·m^-3 CH₂O groups. The Chao1 and Shannon index significantly increased in the 0.054 mg·m^-3 CH₂O group at 6 week, while they remained unchanged in the 0.25 mg·m^-3 CH₂O group. At 12 week, the Chao1 significantly increased in the 0.25 mg·m^-3 CH₂O group, while it remained unchanged in the 0.054 mg·m^-3 CH₂O group. Only a few Operational Taxonomic Units (OTUs) significantly correlated with the CH₂O concentration. CH₂O-induced OTUs mainly belong to the Proteobacteria and Firmicutes. Furthermore, bacterial communities formed at 6 or 12 weeks differed significantly among different CH₂O levels. Functional analysis of bacterial communities showed that inferred genes related to chemical degradation and diseases were the highest in the 0.25 mg·m^-3 CH₂O group at 12 weeks. The development of nematodes fed with bacteria collected at 12 weeks was applied to evaluate the bacterial community's hazards. This showed significantly impaired growth in the 0.1 mg·m^-3 and 0.25 mg·m^-3 CH₂O groups. These findings confirmed that CH₂O concentration and exposure time could affect the indoor bacterial community and formed bacterial communities with a possibly more significant hazard to human health after long-term exposure to high CH₂O levels.

Reviews in environmental health: How systematic are they?

BACKGROUND

Synthesizing environmental health science is crucial to taking action to protect public health. Procedures for evidence evaluation and integration are transitioning from "expert-based narrative" to "systematic" review methods. However, little is known about the methodology being utilized for either type of review.

OBJECTIVES

To appraise the methodological strengths and weaknesses of a sample of "expert-based narrative" and "systematic" reviews in environmental health.

METHODS

We conducted a comprehensive search of multiple databases and identified relevant reviews using pre-specified eligibility criteria. We applied a modified version of the Literature Review Appraisal Toolkit (LRAT) to three environmental health topics that assessed the utility, validity and transparency of reviews.

RESULTS

We identified 29 reviews published between 2003 and 2019, of which 13 (45%) were self-identified as systematic reviews. Across every LRAT domain, systematic reviews received a higher percentage of "satisfactory" ratings compared to non-systematic reviews. In eight of these domains, there was a statistically significant difference observed between the two types of reviews and "satisfactory" ratings. Non-systematic reviews performed poorly with the majority receiving an "unsatisfactory" or "unclear" rating in 11 of the 12 domains. Systematic reviews performed poorly in six of the 12 domains; 10 (77%) did not state the reviews objectives or develop a protocol; eight (62%) did not state the roles and contribution of the authors, or evaluate the internal validity of the included evidence consistently using a valid method; and only seven (54%) stated a pre-defined definition of the evidence bar on which their conclusions were based, or had an author disclosure of interest statement.

DISCUSSION

Systematic reviews produced more useful, valid, and transparent conclusions compared to non-systematic reviews, but poorly conducted systematic reviews were prevalent. Ongoing development and implementation of empirically based systematic review methods are required in environmental health to ensure transparent and timely decision making to protect the public's health.

Work-related Hazards Among Pathologists and Residents of Pathology:Results of a Cross-sectional Study in Iran

BACKGROUND & OBJECTIVE

Pathologists as medical professionals involved in the diagnosis and planning of therapies in many diseases are exposed to occupational hazards in workplaces. Hence, we aimed to determine the occupational health problems among Iranian pathologists in this cross-sectional study.

METHODS

This cross-sectional study was conducted among the Iranian pathologists. The data required for this study was collected through a self-reported questionnaire containing 48 questions about major occupational health problems, including musculoskeletal problems, visual disorders, workplace characteristics, health behavior, and other medical conditions.

RESULTS

Among the study participants (N=350), 87.4% presented with musculoskeletal disorders in the past year, with the neck as the most common location of pain (71%). Musculoskeletal pain was significantly higher in those working with the computer for more than 5 hours per day (P=0.007). Furthermore, 273 (78%) participants reported visual refractive errors, and myopia was the most common error (53%). Acute injuries were reported in 263 (75%) participants, and the cutting injury had the highest frequency (56.6%). Depression was reported in 54 (15.4%) of the participants, followed by burnout (10.3%) and hypertension (4%). Intolerance reactions to formalin were reported by 222 (63.6%) and were significantly more frequent among the residents (P<0.001). The residents were more prone to musculoskeletal pain (P=0.002) and injury (P=0.026).

CONCLUSION

We observed a noticeable prevalence of health risks, including musculoskeletal problems, visual disturbances, injuries, and ergonomic problems among the Iranian pathologists. Solving these problems demands thorough prevention and personal protection, as well as educational programs with more attention toward optimization of ergonomics in the workplace and awareness about chemical and biological hazards.

Current State of Indoor Air Phytoremediation Using Potted Plants and Green Walls

Urban civilization has a high impact on the environment and human health. The pollution level of indoor air can be 2–5 times higher than the outdoor air pollution, and sometimes it reaches up to 100 times or more in natural/mechanical ventilated buildings. Even though people spend about 90% of their time indoors, the importance of indoor air quality is less noticed. Indoor air pollution can be treated with techniques such as chemical purification, ventilation, isolation, and removing pollutions by plants (phytoremediation). Among these techniques, phytoremediation is not given proper attention and, therefore, is the focus of our review paper. Phytoremediation is an affordable and more environmentally friendly means to purify polluted indoor air. Furthermore, studies show that indoor plants can be used to regulate building temperature, decrease noise levels, and alleviate social stress. Sources of indoor air pollutants and their impact on human health are briefly discussed in this paper. The available literature on phytoremediation, including experimental works for removing volatile organic compound (VOC) and particulate matter from the indoor air and associated challenges and opportunities, are reviewed. Phytoremediation of indoor air depends on the physical properties of plants such as interfacial areas, the moisture content, and the type (hydrophobicity) as well as pollutant characteristics such as the size of particulate matter (PM). A comprehensive summary of plant species that can remove pollutants such as VOCs and PM is provided. Sources of indoor air pollutants, as well as their impact on human health, are described. Phytoremediation and its mechanism of cleaning indoor air are discussed. The potential role of green walls and potted-plants for improving indoor air quality is examined. A list of plant species suitable for indoor air phytoremediation is proposed. This review will help in making informed decisions about integrating plants into the interior building design.

Exposure to formaldehyde and asthma outcomes: A systematic review, meta-analysis, and economic assessment

BACKGROUND

Every major federal regulation in the United States requires an economic analysis estimating its benefits and costs. Benefit-cost analyses related to regulations on formaldehyde exposure have not included asthma in part due to lack of clarity in the strength of the evidence.

OBJECTIVES

1) To conduct a systematic review of evidence regarding human exposure to formaldehyde and diagnosis, signs, symptoms, exacerbations, or other measures of asthma in humans; and 2) quantify the annual economic benefit for decreases in formaldehyde exposure.

METHODS

We developed and registered a protocol in PROSPERO (Record ID #38766, CRD 42016038766). We conducted a comprehensive search of articles published up to April 1, 2020. We evaluated potential risk of bias for included studies, identified a subset of studies to combine in a meta-analysis, and rated the overall quality and strength of the evidence. We quantified economics benefit to children from a decrease in formaldehyde exposure using assumptions consistent with EPA's proposed formaldehyde rule.

RESULTS

We screened 4,821 total references and identified 150 human studies that met inclusion criteria; of these, we focused on 90 studies reporting asthma status of all participants with quantified measures of formaldehyde directly relevant to our study question. Ten studies were combinable in a meta-analysis for childhood asthma diagnosis and five combinable for exacerbation of childhood asthma (wheezing and shortness of breath). Studies had low to probably-low risk of bias across most domains. A 10-μg/m3 increase in formaldehyde exposure was associated with increased childhood asthma diagnosis (OR = 1.20, 95% CI: [1.02, 1.41]). We also found a positive association with exacerbation of childhood asthma (OR = 1.08, 95% CI: [0.92, 1.28]). The overall quality and strength of the evidence was rated as "moderate" quality and "sufficient" for asthma diagnosis and asthma symptom exacerbation in both children and adults. We estimated that EPA's proposed rule on pressed wood products would result in 2,805 fewer asthma cases and total economic benefit of $210 million annually.

CONCLUSION

We concluded there was "sufficient evidence of toxicity" for associations between exposure to formaldehyde and asthma diagnosis and asthma symptoms in both children and adults. Our research documented that when exposures are ubiquitous, excluding health outcomes from benefit-cost analysis can underestimate the true benefits to health from environmental regulations.

Chemical risk in hospital settings: Overview on monitoring strategies and international regulatory aspects

Chemical risk in hospital settings is a growing concern that health professionals and supervisory authorities must deal with daily. Exposure to chemical risk is quite different depending on the hospital department involved and might origin from multiple sources, such as the use of sterilizing agents, disinfectants, detergents, solvents, heavy metals, dangerous drugs, and anesthetic gases. Improving prevention procedures and constantly monitoring the presence and level of potentially toxic substances, both in workers (biological monitoring) and in working environments (environmental monitoring), might significantly reduce the risk of exposure and contaminations. The purpose of this article is to present an overview on this subject, which includes the current international regulations, the chemical pollutants to which medical and paramedical personnel are mainly exposed, and the strategies developed to improve safety conditions for all healthcare workers.

Proposal for a neurotoxic classification for chemicals at work

Many neurotoxic chemicals are used in the workplace but there is currently no database dedicated to neurotoxicity. We aimed to develop a classification method for neurotoxicity based on a weight-of-evidence approach, similar to the IARC classification for carcinogenicity. Human and animal lines of evidence were collected from recent toxicological profiles and a literature search and were combined into six groups from neurotoxic to potentially not neurotoxic. The method was tested on 26 chemicals, mixtures or group of products used in the workplace in France: 31% were considered neurotoxic, 31% probably and 11% possibly neurotoxic, and 27% not classifiable because of insufficient data. This operational method suggests that many chemicals used in the workplace are neurotoxic and that questionnaires used to collect data on occupational chemical exposure should propose items with more targeted compounds that have common chemical or toxic properties to improve risk assessment.

Oxidative damage, inflammation, genotoxic effect, and global DNA methylation caused by inhalation of formaldehyde and the purpose of melatonin

Formaldehyde (FA) exposure has been proven to increase the risk of asthma and cancer. This study aimed to evaluate for 28 days the FA inhalation effects on oxidative stress, inflammation process, genotoxicity, and global DNA methylation in mice as well as to investigate the potential protective effects of melatonin. For that, analyses were performed on lung, liver and kidney tissues, blood, and bone marrow. Bronchoalveolar lavage was used to measure inflammatory parameters. Lipid peroxidation (TBARS), protein carbonyl (PCO), non-protein thiols (NPSH), catalase activity (CAT), comet assay, micronuclei (MN), and global methylation were determined. The exposure to 5-ppm FA resulted in oxidative damage to the lung, presenting a significant increase in TBARS and NO levels and a decrease in NPSH levels, besides an increase in inflammatory cells recruited for bronchoalveolar lavage. Likewise, in the liver tissue, the exposure to 5-ppm FA increased TBARS and PCO levels and decreased NPSH levels. In addition, FA significantly induced DNA damage, evidenced by the increase of % tail moment and MN frequency. The pretreatment of mice exposed to FA applying melatonin improved inflammatory and oxidative damage in lung and liver tissues and attenuated MN formation in bone marrow cells. The pulmonary histological study reinforced the results observed in biochemical parameters, demonstrating the potential beneficial role of melatonin. Therefore, our results demonstrated that FA exposure with repeated doses might induce oxidative damage, inflammatory, and genotoxic effects, and melatonin minimized the toxic effects caused by FA inhalation in mice.

Chemicals inhaled from spray cleaning and disinfection products and their respiratory effects. A comprehensive review

Spray cleaning and disinfection products have been associated with adverse respiratory effects in professional cleaners and among residents doing domestic cleaning. This review combines information about use of spray products from epidemiological and clinical studies, in vivo and in vitro toxicological studies of cleaning chemicals, as well as human and field exposure studies. The most frequent chemicals in spray cleaning and disinfection products were compiled, based on registrations in the Danish Product Registry. The chemicals were divided into acids, bases, disinfectants, fragrances, organic solvents, propellants, and tensides. In addition, an assessment of selected cleaning and disinfectant chemicals in spray products was carried out. Chemicals of concern regarding respiratory effects (e.g. asthma) are corrosive chemicals such as strong acids and bases (including ammonia and hypochlorite) and quaternary ammonium compounds (QACs). However, the evidence for respiratory effects after inhalation of QACs is ambiguous. Common fragrances are generally not considered to be of concern following inhalation. Solvents including glycols and glycol ethers as well as propellants are generally weak airway irritants and not expected to induce sensitization in the airways. Mixing of certain cleaning products can produce corrosive airborne chemicals. We discuss different hypotheses for the mechanisms behind the development of respiratory effects of inhalation of chemicals in cleaning agents. An integrative assessment is needed to understand how these chemicals can cause the various respiratory effects.

Formaldehyde toxicity reports from in vitro and in vivo studies: a review and updated data

Formaldehyde (FA) is a xenobiotic air pollutant and its universal distribution causes a widespread exposure to humans. This review aimed to bring updated information concerning FA toxicity in humans and animals based on in vitro and in vivo studies from 2013 to 2019. Researches were carried out in Pubmed, Scopus, and Science Direct databases to determine the effects of FA exposure on inflammation, oxidative stress and genotoxicity in experimental studies with animals (rats and mice) and humans. Besides, in vitro studies assessing FA cytotoxicity focusing on cell viability and apoptosis in different cell line cultures were reviewed. Studies with humans gave evidence regarding significant deleterious effects on health associated to chronic FA occupational exposure. Evaluations carried out in experimental studies showed toxic effects on different organs as lung, upper respiratory tract, bone marrow and brain as well as in cells. In summary, this study demonstrates that knowing the mechanisms underlying FA toxicity is essential to understand the deleterious effects that this xenobiotic causes on biological systems.

Formaldehído en ambientes laborales: revisión de la literatura y propuesta de vigilancia ocupacional

Introducción. El formaldehído es una sustancia ampliamente usada a nivel industrial; sin embargo, es considerada un agente mutagénico y carcinógeno para los humanos. Para determinar el grado de riesgo de los trabajadores ocupacionalmente expuestos (TOE) al formaldehído, debe hacerse un seguimiento de sus niveles de concentración ambiental y de los biomarcadores que permiten identificar su daño potencial para la salud. En Colombia, lamentablemente, no existen lineamientos respecto a la exposición ocupacional a esta sustancia.Objetivo.Revisar estudios recientes sobre exposición ocupacional a formaldehído para diseñar una estrategia de seguimiento y vigilancia de los TOE a esta sustancia en Colombia.Materiales y métodos. Se realizó una revisión de la literatura en PubMed, MedLine, ScienceDirect y Embase mediante la siguiente estrategia de búsqueda: artículos sobre exposición ocupacional a formaldehído publicados en inglés o español entre 2013 y 2017. Los términos de búsqueda fueron “occupational exposure”, “formaldehyde” “mutagenicity test” y “DNA adducts” y sus equivalentes en español.Resultados. La búsqueda inicial arrojó 103 registros, sin embargo solo 36 artículos cumplieron los criterios de inclusión establecidos.Conclusiones. La gestión adecuada del riesgo derivado de la exposición ocupacional a formaldehido, así como el seguimiento médico apropiado de estos trabajadores, requiere la implementación de una serie de acciones interdisciplinarias que permitan la creación de un sistema de vigilancia ocupacional integral de los TOE a esta sustancia. 

Surface Plasmon-Enhanced Optical Formaldehyde Sensor Based on CdSe@ZnS Quantum Dots

For the first time, a reproducible surface plasmon-enhanced optical sensor for the detection of gaseous formaldehyde was proposed, which was fabricated by depositing a mixture of CdSe@ZnS quantum dots (QDs), fumed silica (FS), and gold nanoparticles (GNs) on the surface of a silica sphere array to meet the urgent requirement of a rapid, sensitive, and highly convenient formaldehyde detection method. Because of the spectral overlap between QDs and GNs, plasmon-enhanced fluorescence was observed in the film of QDs/FS/GNs. When exposed to formaldehyde molecules, the enhanced fluorescence was quenched linearly with the increase of formaldehyde concentration in the range of 0.5-2.0 ppm. The reason is attributed to the nonradiative electron transfer from QDs to the carbonyl of formaldehyde molecules with the assistance of amino groups. Our results demonstrate that the designed sensors are capable of detecting ultralow concentration gaseous formaldehyde at room temperature with a fast response-recovery time and excellent selectivity, stability, and reproducibility. This work provides a simple and low-cost approach for optical formaldehyde sensor fabrication and shows promising applications in environmental detection.

Combined cell death of co-exposure to aldehyde mixtures on human bronchial epithelial BEAS-2B cells: Molecular insights into the joint action

Aldehydes are common air pollutants and metabolites of the organism, which widely exist in many in vivo (e.g. Alzheimer's disease) and in vitro (e.g. cigarette smoke) situations. Individual aldehydes have been studied well alone, while their combined toxicity is still obscure. Here, we examined the combined apoptosis of aldehyde mixtures in BEAS-2B cells at smoking-related environmental/physiologically relevant concentrations, and the potential mechanism was investigated further based on the related signaling pathway. Co-exposure to aldehyde mixtures demonstrated significant synergistic interaction on apoptosis in a concentration-dependent manner, which differed from the expectation based on single aldehydes. Moreover, formaldehyde significantly potentiated the induction of death receptor-5, caspase 8/10, cleaved caspase 3/7/9, pro-apoptotic proteins (Bim, Bad and Bax), depolarization of MMP (mitochondrial membrane potential) and AIF (apoptosis-inducing factor) induced by acrolein, and synergistically decreased expressions of pro-survival proteins (Bcl-2 and Bcl-XL) and poly ADP-ribose polymerase. Therefore, aldehyde mixture-induced synergistic apoptosis was mediated both by TRAIL death receptor and mitochondrial pathway. Additionally, reactive oxygen species, Ca²⁺ levels, DNA damage, and phosphorylated MDM2 were all synergistically induced by aldehyde mixtures, while total p53, phosphorylated p53 and phosphorylated AKT (serine/threonine kinase) were inhibited. Antioxidants N-acetylcysteine suppressed the aldehyde mixture-induced ROS, DNA damage and apoptosis, and blocked the TRAIL death receptor and mitochondrial pathway, while it did not rescue the p53 and AKT pathway. Briefly, aldehyde mixtures induced synergistic apoptosis even at smoking-related environmental/physiologically relevant concentrations, which could be enhanced through ROS-mediated death receptor/mitochondrial pathway, and the down-regulation of phosphorylated AKT.

Indoor air chemistry: Terpene reaction products and airway effects

Reactive chemistry is ubiquitous indoors with a wealth of complex oxidation reactions; some of these are initiated by both homogeneous and heterogeneous reaction of ozone with unsaturated organic compounds and subsequent the hydroxyl radical, either in the gas-phase or on reactive surfaces. One major focus has been the reaction of common and abundant terpene-based fragrances in indoor air emitted from many wood-based materials, a variety of consumer products, and citrus fruits and flowers. Inhalation of the terpenes themselves are generally not considered a health concern (both acute and long-term) due to their low indoor air concentrations; however, their gas- and surface reactions with ozone and the hydroxyl radical produce a host of products, both gaseous, i. a. formaldehyde, and ultrafine particles formed by condensation/nucleation processes. These reaction products may be of health concern. Human cell bioassays with key reaction products from ozone-initiated terpene reactions have shown some inflammatory reactions, but results are difficult to interpret for human exposure and risk assessment. Acute effects like sensory irritation in eyes and airways are unlikely or present at very low intensity in real life conditions based on rodent and human exposure studies and known thresholds for sensory irritation in eyes and airways and derived human reference values for airflow limitation and pulmonary irritation. Some fragrances and their ozone-initiated reaction products may possess anti-inflammatory properties. However, long-term effects of the reaction products as ultrafine particles are poorly explored. Material and product surfaces with high ozone deposition velocities may significantly impact the perceived air quality by altered emissions from both homogeneous and heterogeneous surface reactions.

Exposure to both formaldehyde and high relative humidity exacerbates allergic asthma by activating the TRPV4-p38 MAPK pathway in Balb/c mice

Some studies have indicated that formaldehyde, a ubiquitous environmental pollutant, can induce or aggravate allergic asthma. Epidemiological studies have also shown that the relative humidity indoors may be an independent and a key factor associated with the aggravation of allergic asthma. However, the synergy of humidity and formaldehyde on allergic asthma and the mechanism underlying this effect remain largely unknown. In this study, we aim to determine the effect of high relative humidity and/or formaldehyde exposure on allergic asthma and explore the underlying mechanisms. Male Balb/c mice were modeled with ovalbumin (OVA) and exposure to 0.5 mg/m³ formaldehyde and/or different relative humidity (60%/75%/90%). Histopathological changes, pulmonary function, Th1/Th2 balance, the status of mucus hypersecretion and the levels of inflammatory factors were detected to assess the exacerbation of allergic asthma. The levels of the transient receptor potential vanilloid 4 (TRPV4), calcium ion and the activation of p38 mitogen-activated protein kinases (p38 MAPK) were detected to explore the underlying mechanisms. The results showed that exposure to high relative humidity or to 0.5 mg/m³ formaldehyde alone had a slight, but not significant, affect on allergic asthma. However, the pathological response and airway hyperresponsiveness (AHR) were greatly aggravated by simultaneous exposure to 0.5 mg/m³ formaldehyde and 90% relative humidity. Blocking TRPV4or p38 MAPK using HC-067047 and SB203580 respectively, effectively alleviated the exacerbation of allergic asthma induced by this simultaneous exposure to formaldehyde and high relative humidity. The results show that when formaldehyde and high relative humidity are present this can enhance the activation of the TRPV4 ion channel in the lung leading to the aggravation of the p38 MAPK activation, resulting in the exacerbation of inflammation and hypersecretion of mucus in the airways.

Assessment of formaldehyde levels in relation to respiratory and allergic symptoms in children from Alba County schools, Romania

Our study assessed the exposure to formaldehyde of Romanian school children in relation to the classroom indoor environment characteristics and respiratory and allergic symptoms reported in a questionnaire survey, using the data collected in the SINPHONIE (Schools Indoor Pollution and Health: Observatory Network in Europe) project. Measurements of formaldehyde and microclimate parameters were conducted in three classrooms per school, in five schools, together with one outdoor measurement at each school. Questionnaires were used to collect information on classroom characteristics and health effects among children. The indoor formaldehyde levels for a school week varied between 15.5 and 66.2 μg/m³, with a median value of 34.8 μg/m³. The adjusted odds ratios for allergy-like, asthma-like, and flu-like symptoms were 3.23 (95% CI 1.31-8.00), 2.69 (95% CI 1.04-6.97), and 2.39 (95% CI 1.04-5.50), respectively, when exposed to higher formaldehyde levels (≥ 35 μg/m³) during a school week, compared to lower formaldehyde level exposure (< 35 μg/m³). Higher levels of indoor formaldehyde were significantly associated with health symptoms in children. The high indoor formaldehyde levels were related to the use of water-resistant paint for ceiling coverings, moisture damage signs, and lower classroom natural ventilation rates.

Secondary product creation potential (SPCP): a metric for assessing the potential impact of indoor air pollution on human health

Indoor air is subject to emissions of chemicals from numerous sources. Many of these emissions contain volatile organic compounds (VOCs), which react to form a wide range of secondary products, some with adverse health effects. However, at present we lack a robust, standardised approach to rank the potential for different VOCs to cause harm, which prevents effective action to improve indoor air quality and reduce impacts on human health. This paper uses a detailed chemical model to quantify the impact of 63 VOCs on indoor air quality. We define a novel method for ranking the VOCs in terms of potentially harmful product formation through a new metric, the Secondary Product Creation Potential (SPCP). We established SPCPs for a range of ventilation rates, different proportions of transmitted outdoor light, as well as for varying outdoor concentrations of ozone and nitrogen oxides. The species having the largest SPCPs are the alkenes, terpenes and aromatic VOCs. trans-2-Butene has the largest individual SPCP owing to the ratio of its rate coefficient for reaction with the hydroxy radical relative to ozone. Increasing the proportion of outdoor transmitted light increased most SPCPs markedly. This is because oxidant levels increased under these conditions and promoted more chemical processing, suggesting that there may be more harmful products closer to a window than further from the attenuated outdoor light. The SPCP is the first metric for assessing the impact of different VOCs on human health and will be an essential tool for guiding the composition of products commonly used indoors.

Derivation of safe exposure levels for potential migration of formaldehyde into food

Polyoxymethylene (POM) is a polymer of formaldehyde used inter alia for kitchenware and food processing machines. By migration into food, consumers may be exposed to small additional amounts of formaldehyde in food. In order to address such potential exposures, Specific Migration Limits are derived using all studies with oral exposure in mammals and birds. The assessment is not only based on local irritation observed in a 2-year rat study that has previously served to calculate acceptable exposure levels, but also on systemic effects, namely on effects on the kidney in adult rats and testes in birds before sexual maturity. At the relatively high oral exposure levels (up to 2000 ppm in drinking water) long-term effects caused by formic acid, the first step metabolite of formaldehyde, such as acidosis, cannot be excluded. The lowest Specific Migration Limit of 2.74 mg/dm², corresponding to 16.5 mg formaldehyde/kg food, is based upon kidney effects in rats, leading to potential exposures that range between 2900 and 4400 times below the endogenous turnover of formaldehyde. Lastly, a recent migration study with POM showed that migration of formaldehyde into food simulants is over an order of magnitude below the lowest Specific Migration Limit derived herein.