Microextraction techniques for occupational biological monitoring: Basic principles, current applications and future perspectives.

The application of green microextraction techniques (METs) is constantly being developed in different areas including pharmaceutical, forensic, food and environmental analysis. However, they are less used in biological monitoring of workers in occupational settings. Developing valid extraction methods and analytical techniques for the determination of occupational indicators plays a critical role in the management of workers' exposure to chemicals in workplaces. Microextraction techniques have become increasingly important because they are inexpensive, robust and environmentally friendly. This study aimed to provide a comprehensive review and interpret the applications of METs and novel sorbents and liquids in biological monitoring. Future perspectives and occupational indicators that METs have not yet been developed for are also discussed.

Enhanced adsorption of toluene on thermally activated ZIF-67: Characterization, performance, and modeling insights.

The zeolitic imidazolate framework-67 (ZIF-67) has been explored for the dynamic adsorption of toluene vapor. We synthesized ZIF-67 through a straightforward room-temperature process and characterized it using XRD, FT-IR, DLS, and SEM techniques. The synthesized ZIF-67 possessed a Brunauer-Emmett-Teller (BET) surface area of 1578.7 m2/g and 0.76 µm particle size. Thermal activation under various conditions revealed that ZIF-67, activated in dry air at 250 °C, demonstrated optimal adsorption efficacy. Its adsorption capacity, time of breakthrough, and time of equilibration were 414.5 mg/g, 420 min, and 795 min, respectively. We investigated the impact of diverse operational parameters on adsorption through breakthrough curve analysis. An increase in the toluene concentration from 100 to 1000 ppm enhanced the adsorption capacity from 171 to 414 mg/g, while breakthrough time decreased from 1260 min to 462 min, respectively. Our findings show that increasing relative humidity from 0 to 70 % reduced 53.7 % in adsorption capacity and 46.3 % in breakthrough time. The competitive adsorption of toluene and ethylbenzene revealed that ZIF-67 had a higher selectivity for toluene adsorption. A 98 % adsorbent's regeneration efficiency at the first cycle reveals its reusability. The experimental data were successfully fitted to the Yan, Thomas, and Yoon-Nelson models to describe the adsorption process. The statistical validation of the model parameters confirms their reliability for estimating adsorption parameters, thus facilitating the design of fixed-bed adsorption columns for practical applications.

Rapid determination of hippuric acid as an exposure biomarker of toluene using a colorimetric assay and comparison with high-performance liquid chromatography.

Occupational exposure to toluene is associated with health risks that require reliable monitoring methods. Hippuric acid (HA), a urinary metabolite of toluene, serves as a valuable biomarker for such exposure. Colorimetric methods for the quantitative determination of HA have gained prominence due to their simplicity, cost-effectiveness, and suitability for field application. In the present study, a simple colorimetric technique was optimized for the determination of HA in the urine sample, and compared with a usual HPLC technique. The central composite design (CCD) was applied to examine the effective parameters on the colorimetric determination of HA. The calibration curve for HA was established within the concentration range of 6 to 100 mg L-1 with R2 = 0.97. The detection limit (LOD) and quantification limit (LOQ) were determined to be 1.8 mg L-1 and 6 mg L-1 respectively. The relative standard deviation (RSD%) was less than 5%, and the recovery% (R%) was 90.5-100.1. The overall results showed good agreement between the colorimetric and HPLC results. There was a significant relationship between the results obtained from HPLC and colorimetric methods especially for higher concentration levels of HA (≥ 500 mg/g creatinine). In conclusion, our optimized colorimetric method is a simple, cost-effective, and rapid method for determination of HA in occupational exposure, which is comparable with the HPLC technique.

Systemic inflammation indices as hematological biomarkers of inflammatory response in non-silicotic workers exposed to respirable silica dust.

This cross-sectional study was performed to assess whether systemic inflammatory indices, including systemic inflammation response index (SIRI), systemic immune­inflammation index (SII), and aggregate index of systemic inflammation (AISI), can be considered as possible inflammatory markers in silica-exposed workers with no diagnosis of silicosis. We studied 371 non-silicotic workers exposed to respirable silica dust (RSD) and 1422 reference workers. The workers' exposure to RSD were assessed and the inflammatory indices were compared between subgroups of the exposed workers based on the severity and duration of exposure. Correlations between inflammatory indices and the pulmonary function parameters were investigated. Also, the receiver operating characteristic (ROC) curve and Youden index were used to determine the cut-off values of the SII, SIRI, and AISI. Significant dose-response relationships were observed between duration of exposure and all indices except monocytes and LMR. No significant interaction was observed between duration of exposure to RSD and smoking. Borderline significant correlations were observed between AISI and SIRI with forced expiratory volume (FEV1) and FEV1 to forced vital capacity (FVC) ratio. Higher AUCs were obtained for SII and AISI, respectively. The cut-off values for these biomarkers to be considered abnormal were > 348.48 for SII, > 183.78 for AISI, and > 0.768 for SIRI. Overall, the present study showed for the first time, that SII, AISI, and SIRI might be considered as available, easy-to-obtain, and non-expensive markers of inflammation in non-silicotic workers with a long duration of exposure to RSD who are at risk of developing silicosis in subsequent years.

False positives and false negatives in benzene biological monitoring.

Benzene is a commonly used industrial chemical that is a significant environmental pollutant. Occupational health specialists and industrial toxicologists are concerned with determining the exact amount of exposure to chemicals in the workplace. There are two main approaches to assess chemical exposure; air monitoring and biological monitoring. Air monitoring has limitations, which biological monitoring overcomes and could be used as a supplement to it. However, there are several factors that influence biological monitoring results. It would be possible to assess exposure more accurately if these factors were taken into account. This study aimed to review published papers for recognizing and discussing parameters that could affect benzene biological monitoring. Two types of effects can be distinguished: positive and negative effects. Factors causing positive effects will increase the metabolite concentration in urine more than expected. Furthermore, the parameters that decrease the urinary metabolite level were referred to as false negatives. From the papers, sixteen influential factors were extracted that might affect benzene biological monitoring results. Identified factors were clarified in terms of their nature and mechanism of action. It is also important to note that some factors influence the quantity and quality of the influence of other factors. As a result of this study, a decision-making protocol was developed for interpreting the final results of benzene biological monitoring.

Simultaneous Analysis of Mycotoxins, Potentially Toxic Elements, and Pesticides in Rice: A Health Risk Assessment Study.

Rice is a widely consumed food worldwide; however, it can be a source of pollutants, such as potentially toxic elements (PTEs), mycotoxins, and pesticides. Sixty rice samples imported from Pakistan (PAK), India (IND), and Thailand (THAI), as well as domestic Iranian (IRN) rice, were collected from Bushehr, Iran, and investigated for the contamination of PTEs, including arsenic (As), lead (Pb), cadmium (Cd), and nickel (Ni); pesticides, including chlorpyrifos, trichlorfon, diazinon, fenitrothion, and chlorothalonil; mycotoxins, such as aflatoxin B1 (AFB1), zearalenone (ZEN), ochratoxin A (OTA), and deoxynivalenol (DON); and molds. Estimated daily intake (EDI) and hazard quotient (HQ) of pollutants and hazard index (HI) and incremental lifetime cancer risk (ILCR) of rice types for the Iranian adult population were calculated. The content of PTEs in Iranian rice was not higher than Iran's national standard limits. In contrast, other types of rice (imported) had at least one PTE above the permissible level. OTA content was below the detection limit, and all other mycotoxins were within the allowable range in all rice types. Thai rice was the only group without pesticides. The HI order of rice types was as follows: HIPAK = 2.1 > HIIND = 1.86 > HIIRN = 1.01 > HITHAI = 0.98. As was the biggest contributor to the HI of Iranian and Thai rice, and diazinon in the HI of Pakistani and Indian rice. The calculation of ILCR confirmed that the concentrations of Ni and Pb in Pakistani and Ni and As in Indian, Thai, and Iranian rice were not acceptable in terms of lifetime carcinogenic health risks.

Blood volatile organic compounds as potential biomarkers for poly cystic ovarian syndrome (PCOS): An animal study in the PCOS rat model.

Polycystic ovary syndrome (PCOS) as a common metabolic and endocrinological disorder can affect the metabolic profile in biological fluids. We studied the profile of blood volatile organic compounds (VOCs) in rats with PCOS and controls to identify potential specific biomarkers of blood VOCs in PCOS rats. For this purpose, 30 female adult Wistar rats were assigned to two groups: control and PCOS groups. PCOS model was induced using letrozole gavage (1 mg/kg) for 21 days. The rats in the control group received water of the same volume for 21 days. During treatment, a collection of vaginal smears was done every day for estrus cycle determination and weight was measured weekly. On the day after the last administration of letrozole, the rats were killed and their blood and ovaries were collected. Testosterone levels and histologic changes in ovaries were examined. Also, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analyzed the VOCs in the blood of PCOS and control rats. Multivariate and univariate statistical analyses were used to find the potential biomarkers for a rat model of PCOS. Weight gain, ovarian and vaginal pathological alteration, as well as hyperandrogenemia, confirmed the successful induction of the PCOS in rats. The results of blood VOCs analysis showed that nine VOCs were significantly elevated and one VOC decreased in the PCOS group than the control group (P < 0/05). The partial least-squares discriminant analysis (PLS-DA) and principal component analysis (PCA) showed good separation of VOCs between the PCOS rats and the control group. The 4-ethylphenol and capric (decanoic) acid were selected as the potential biomarkers for PCOS diagnosis in the blood of the PCOS rats. The blood of PCOS rats had a specific profile of VOCs, which could be detected by GC-MS analysis. These findings can pave the way for further studies towards developing a new screening method for PCOS detection and studying their pathology, based on VOCs analysis.

Pulmonary function and respiratory symptoms in workers exposed to respirable silica dust: A historical cohort study.

Background: The adverse health effects of silica are still a major concern in some industries. The purpose of this study was to evaluate pulmonary function in a group of sub-radiological silicotic workers after 11 years of silica dust exposure. Methods: The study sample consisted of 381 exposed and 254 non-exposed workers. The history of pulmonary function parameters was obtained from workers' medical records. The data were collected through interviews with employees and completing questionnaires on demographic variables, detailed occupational and medical history, and respiratory symptoms. Workers' exposure to silica dust was also determined. Results: The mean frequency of workers' exposure to silica dust was 6.3 times greater than its exposure limit. All pulmonary function parameters were significantly lower in the silica-exposed workers, and the difference between the two groups was still statistically significant after adjusting the potential confounding variables. FEV1 showed the greatest reduction, and FVC and FEV1 showed a significant decreasing trend. Also the prevalence of respiratory symptoms was significantly higher in smokers than in nonsmokers among silica-exposed workers. Conclusions: Even in the absence of radiographic evidence of silicosis, exposure to high levels of silica dust is associated with reductions in pulmonary function. In the absence of radiological evidence of silicosis, progressive deterioration of FEV1 over time most likely indicates sub-radiological silicosis. The effects were associated with the severity and duration of exposure. Exposure to sub-TLV levels of silica dust may not affect pulmonary function. Smoking appears to have a synergistic effect in relatively high silica exposures.

Metabolomics for exposure assessment and toxicity effects of occupational pollutants: current status and future perspectives.

INTRODUCTION: Work-related exposures to harmful agents or factors are associated with an increase in incidence of occupational diseases. These exposures often represent a complex mixture of different stressors, challenging the ability to delineate the mechanisms and risk factors underlying exposure-disease relationships. The use of omics measurement approaches that enable characterization of biological marker patterns provide internal indicators of molecular alterations, which could be used to identify bioeffects following exposure to a toxicant. Metabolomics is the comprehensive analysis of small molecule present in biological samples, and allows identification of potential modes of action and altered pathways by systematic measurement of metabolites. OBJECTIVES: The aim of this study is to review the application of metabolomics studies for use in occupational health, with a focus on applying metabolomics for exposure monitoring and its relationship to occupational diseases. METHODS: PubMed, Web of Science, Embase and Scopus electronic databases were systematically searched for relevant studies published up to 2021. RESULTS: Most of reviewed studies included worker populations exposed to heavy metals such as As, Cd, Pb, Cr, Ni, Mn and organic compounds such as tetrachlorodibenzo-p-dioxin, trichloroethylene, polyfluoroalkyl, acrylamide, polyvinyl chloride. Occupational exposures were associated with changes in metabolites and pathways, and provided novel insight into the relationship between exposure and disease outcomes. The reviewed studies demonstrate that metabolomics provides a powerful ability to identify metabolic phenotypes and bioeffect of occupational exposures. CONCLUSION: Continued application to worker populations has the potential to enable characterization of thousands of chemical signals in biological samples, which could lead to discovery of new biomarkers of exposure for chemicals, identify possible toxicological mechanisms, and improved understanding of biological effects increasing disease risk associated with occupational exposure.

Simultaneous removal of fluoride and nitrate from synthetic aqueous solution and groundwater by the electrochemical process using non-coated and coated anode electrodes: A human health risk study.

Co-presence of fluoride (F-) and nitrate (NO3-) in water causes numerous health complications. Thus, they should be eliminated by an appropriate method like the EC process. In this research, simultaneous removal of F- and NO3- from synthetic aqueous solution and groundwater has been considered by the EC technique under operational parameters like anode materials (un-coated (Al and Fe) and synthesized coated (Ti/TiRuSnO2 and Ti/PbO2)), cathode materials (Cu, St, and Gr), current density (12, 24, and 36 mA/cm2), inter-electrode distance (0.5, 1, and 2 cm), pH (5.5, 7, and 8.5), NaCl concentrations (0.5, 1, and 1.5 g/L), electrolysis time (15, 30, 45, 60, 90, and 120 min), NO3- concentrations (75, 150, and 225 mg/L), and F- concentrations (2, 4, 6, and 8 mg/L) for the first time in this research. The results proved that Al as non-coated anode and Cu as cathode electrodes were more effective in the co-removal of F- and NO3-. The maximum removal efficiencies of 94.19 and 95% were observed at the current density of 36 mA/cm2, 1 cm of inter-electrode distance, pH 7, 1 g/L of NaCl, and 90 min electrolysis time by Al-Cu electrode for F- (2 mg/L) and NO3- (75 mg/L), respectively. The higher efficiency of Al-Cu electrodes was due to the simultaneous occurrence of electrocoagulation, electroreduction, and electrooxidation processes. Al-Cu electrode application considerably diminished f- and NO3- concentrations in the groundwater. Health risk assessment proved that HQ of F- was significantly decreased after treatment by the Al-Cu electrode. Thus, the EC process using an appropriate and effective electrode is a promising technique for treating aqueous solutions containing F- and NO3-.

Improvement of performance and function in respiratory protection equipment using nanomaterials.

Nanotechnology has become one of key areas for the current development and research. Nanotechnology focuses on matter at the nanoscale and is capable of using different approaches to produce nanomaterials, structures, devices, and systems. One of the concerns that have to be addressed is the adverse effects of exposure to pathogens and pollutants in different workplaces and environments. Respiratory protective equipment (RPE) is one of the personal protective equipment (PPE) utilized to reduce the risk of exposure to environmental or occupational respiratory hazards. Thus, various studies have been conducted for improving the functional properties of sorbents or filters in different kinds of RPE. Different categories of nanomaterials have been reported as effective agents for achieving this goal. The application of these nanomaterials in mask layers or respirators' cartridge could significantly increase the filtration efficiency, breathing comfort, and antibacterial/antiviral properties of the masks and respirators. The present study aimed to comprehensively review the nanomaterials used in different types of face RPE with emphasis on various properties of the utilized nanomaterials. The study also aimed to show an applied perspective for future research on this important subject.

Evaluating the effects of dark chocolate formulated with micro-encapsulated fermented garlic extract on cardio-metabolic indices in hypertensive patients: A crossover, triple-blind placebo-controlled randomized clinical trial.

This study aimed to investigate the health-related effects of microencapsulated fermented garlic extract (FGE) containing dark chocolate in hypertensive adults. For this purpose, 36 hypertensive adults (15 males vs. 21 females) were randomized to receive the FGE (5 g/day) dark chocolate containing 650 mg of FGE powder or the placebo. Intervention periods lasted for 6 weeks and were separated by a 3-week wash-out period. The response variables included blood pressure, anthropometric indices, lipid profile, and inflammatory and oxidative stress indices. Statistical analyses were performed using the Pkcross procedure, and Cohen's d was estimated for all response variables. There was no significant inter-period difference between the mean changes of body weight, waist circumference, and body mass index (BMI). Furthermore, no significant change was confirmed in participants' blood pressure, triglycerides, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), very low-density lipoprotein (VLDL), serum homocysteine, high-sensitive c-reactive protein (hs-CRP), malondialdehyde (MDA), and total antioxidant capacity (TAC). It seems that the dose of FGE used in this study was not sufficient to cause any significant changes in the outcomes. Therefore, further studies with dose-response designs and longer durations are recommended.

Evaluation of oxidative stress and biochemical biomarkers, and psychological parameters in cement plant workers.

The cement industry is one of the main world industries with exposure to a wide range of hazardous chemical and physical occupational agents that may increase free radicals and lead to disease. The aim of this study was to evaluate oxidative stress, biochemical markers, and psychological parameters among cement plant workers. In this cross-sectional study, 40 workers exposed to cement and 40 office employees were selected as the exposed and non-exposed groups, respectively. Exposure to cement dust, silica, and noise were, respectively, assessed using the NIOSH 0600, NIOSH 7601, and noise dosimetry methods. Oxidative stress biomarkers including malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (TAC), and biochemical parameters were measured in the serum of all participants. Depression, anxiety, and stress were assessed by the Depression Anxiety Stress Scales (DASS-21) questionnaire. The results demonstrated that the level of MDA as a marker of oxidative stress was significantly higher in the exposed group. The level of antioxidant enzymes including SOD and CAT were also significantly higher in the exposed group. The level of TAC was lower in the exposed group, but the difference was not statistically significant. The levels of alkaline phosphatase (ALP), aspartate transaminase (AST), and the scores of depression and stress were also significantly higher in the exposed group. According to our results, noise, cement dust, and silica exposure were associated with oxidative stress, and this may be one of the mechanisms in which they adversely affect liver function and mental health.

Solidified floating organic droplet microextraction coupled with HPLC for rapid determination of trans, trans muconic acid in benzene biomonitoring.

Benzene is one of the carcinogenic compounds in the work environments. Exposure assessment of benzene through biological monitoring is an acceptable way to accurately measure the real exposure in order to conducting the health risk assessment, but it is always complicated, laborious, time consuming and costly process. A new sensitive, simple, fast and environmental friendly method was developed for the determination of urinary metabolite of benzene, trans trans muconic acid (t,t-MA) by dispersive liquid-liquid micro extraction based on solidification of floating organic droplet coupled with high-performance liquid chromatography with ultra violet detector. Central composite design methodology was utilized to evaluate the effective factors on the extraction output of the target metabolite. The calibration curve was plotted in the concentration ranges of 0.02-5 µg mL-1. The precision and accuracy of the method were assayed via the relative standard deviation (RSD%) and relative recovery (RR%) using spiked samples with three replications. The RR% and RSD% of the optimized method were 86.9-91.3% and 4.3-6.3% respectively. The limit of detection (LOD) of the method was 0.006 µg mL-1. The level of t,t-MA in real samples was ranged from 0.54 to 1.64 mg/g creatinine. We demonstrated that t,t-MA can be extracted and determined by an inexpensive, simple and fast method.

First molecular-based detection of SARS-CoV-2 virus in the field-collected houseflies.

This is the first report of SARS-CoV-2 detection on field-collected Musca domestica housefly surface and tissue samples using the high-sensitive PCR assay which suggests the possible insect-borne transmission. The study was conducted in Shiraz city, southern Iran, in May and Jun 2020. Adult flies were sampled at the outdoor areas of two hospitals treating COVID-19 patients. Fly samples were first washed twice to remove the insect surface attached to SARS-CoV-2 virions. After that, the disinfected fly samples were homogenized. Fly surface washout and homogenate samples were tested using Taq Man real-time PCR assay for the SARS-CoV-2 virus. In a total of 156 houseflies, 75% of samples from the body washout samples were positive for SARS-CoV-2. Strikingly, 37% of the homogenized specimens were positive for the SARS-CoV-2, suggesting the possible infection of the insects or uptake of the virion to the insect metabolism. The other possibility is the houseflies up took the blood or blood fluids of the patients and the RNA of the SARS-CoV-2 survived in the insect body without replicating. Our preliminary findings suggest that the houseflies could transmit SARS-CoV-2 as a mechanical or biological vector especially during the warm seasons while increasing the population and activity of houseflies.

Photocatalytic degradation of 2,4-dichlorophenoxyacetic acid from aqueous solutions by Ag3PO4/TiO2 nanoparticles under visible light: kinetic and thermodynamic studies.

Between the countless chemical substances applied in agriculture, 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is considered as a toxic and carcinogenic pollutant which is difficult to remove from water due to its biological and chemical stability and high solubility. The goal of this study was photocatalytic degradation of 2,4-D, using Ag3PO4/TiO2 nanoparticles under visible light. The Ag3PO4/TiO2 nanoparticles were characterized using XRD, FESEM and EDS analysis to investigate its crystal structure and elemental compounds. The effect of operating parameters such as pH, contact time, catalyst dose, and initial concentration of herbicide on the efficiency of the process was studied. Increasing the pH and initial concentration of herbicide led to the reduction of the efficiency of removing the herbicide, while increasing contact time and catalyst dose increased the efficiency. The best result (98.4% removal efficiency) was achieved at pH = 3, 1 g/L catalyst dose, 60 min contact time, and 10 mg/L initial concentration of 2,4-D. According to the results, 2,4-D removal efficiency with Ag3PO4/TiO2 photocatalyst reached 96.1% from 98.4% after 5 cycles of reaction. The pseudo-first-order kinetics was the best fit for the 2,4-D degradation by Ag3PO4/TiO2 with correlation coefficients (R2 = 0.9945). The results demonstrated that the photocatalytic process using Ag3PO4/TiO2 nanoparticles in the presence of visible light had a relatively good efficiency in removing 2,4-D. Moreover, Ag3PO4/TiO2 can be used as a reusable photocatalyst for the degradation of such toxins from polluted water and wastewater.

In-syringe ionic liquid-dispersive liquid-liquid microextraction coupled with HPLC for the determination of trans,trans-muconic acid in human urine sample.

trans,trans-Muconic acid has been widely used as a biomarker in biological monitoring of benzene-exposed workers during routine occupational health services. In the present study, a novel microextraction technique, in-syringe ionic liquid-dispersive liquid-liquid microextraction, was implemented for preconcentration of trans,trans-muconic acid followed by analytical determination by high-performance liquid chromatography with ultraviolet detection. Moreover, the important variables affecting the performance of applied microextraction technique including needle diameter, volume of the spiked sample, volume of the ionic liquid, salt addition, rotation speed of centrifugation, centrifuge time, and ultrasonic time were optimized by experimental design. A good linear relationship was observed at the range of 0.032-10 µg/mL between the peak area and the concentration levels (R2  = 0.9997). The limit of detection and extraction recovery for trans,trans-muconic acid were 0.011 µg/mL and >96.2%, respectively. This method provided easy and rapid analysis of low amounts of trans,trans-muconic acid in human urine with simple equipment.

Assessment of respiratory exposure to cypermethrin among farmers and farm workers of Shiraz, Iran.

Cypermethrin, a member of the synthetic pyrethroids group, is a popular insecticide used to eliminate a broad range of common bugs in agricultural lands and households. However, studies of farmers' exposure to this insecticide are limited. The present study aimed to measure the respiratory exposure to cypermethrin among farmers and farm workers of Shiraz, as one of the biggest cities in Fars province, Iran. Totally, nine target regions were selected, where 42 individual samples were taken using XAD-2 sorbents and were analyzed by gas chromatography-electron capture detector (GC-ECD). This is the first study on farmers' exposure to insecticides during spraying in Iran. The average concentration of cypermethrin vapor in farmers' respiratory area during spraying was 0.982 ± 0.421 mg/m3, which was lower than the permitted threshold value for cypermethrin recommended by the Occupational Safety and Health Administration (OSHA). The mean time-weighted average (TWA) was also evaluated in two distinct occupational groups (tree operators and field operators). The exposure was significantly higher in tree operators than in field operators. A direct correlation was also found between the height of the workers and the amount of cypermethrin (Spearman's r = 0.555). Findings support that farm workers' respiratory exposure to cypermethrin was within the permissible range, but this situation cannot guarantee workers' safety. Total respiratory exposure and skin exposure studies are recommended in future research.

Erratum to: Toxic responses of the liver and kidneys following occupational exposure to anesthetic gases.

[This corrects the article on p. 418 in vol. 19, PMID: 32327960.].