Association Between Occupational Exposure to Formaldehyde and Cognitive Impairment

Objective:To our knowledge, no study has investigated the effect of exposure to formaldehyde on cognition in the general population. Our objective was to examine the association between occupational exposure to formaldehyde and cognitive impairment in middle-aged and young- old adults (≥45 years).Methods:In the French CONSTANCES cohort, cognitive function was assessed with a standardized battery of seven cognitive tests to evaluate global cognitive function, episodic verbal memory, language abilities and executive functions (e.g., Digit Symbol Substitution Test, DSST). A global cognitive score was created using principal component analysis. Cognitive impairment was assessed in reference to norms of neuropsychological battery according to age, sex and education. Lifetime exposure to formaldehyde was assessed using a French job-exposure matrix created in the framework of the Matgéné project. After performing multiple imputation, separate modified Poisson regression models were used to evaluate the association between cognitive impairment (<25th percentile) and formaldehyde exposure (exposed/never exposed), exposure duration, cumulative exposure index (CEI), and combination of CEI and time of last exposure.Results:Among 75 322 participants (median age: 57.5 years, women: 53%), 8% were exposed to formaldehyde during their professional life. These participants were at higher risk of global cognitive impairment (for global cognitive score: adjusted relative risk, aRR, 1.17, 95% confidence interval, CI: 1.11-1.23), after adjusting for confounders (age, sex, education, income, solvent exposure, Effort–Reward Imbalance, night-shift, repetitive, and noisy work). They were at higher risk of cognitive impairment for all cognitive domains explored. Longer exposure duration and high CEI were associated with cognitive impairment, with a dose-effect relationship for exposure duration. Recent exposure was associated with impairment in all cognitive domains. Time did not fully attenuate formaldehyde-associated cognitive deficits especially in highly exposed individuals (for DSST: high past exposure aRR 1.23, 95%CI: 1.11-1.36; high recent exposure: aRR 1.24, 95%CI: 1.13-1.35).Conclusion:Our findings highlight the long-term detrimental effect of formaldehyde exposure on cognitive health in a relatively young population.

Acceptable Limits for n-Hexane in Spacecraft Atmospheres

INTRODUCTION:The Spacecraft Maximum Allowable Concentrations (SMACs) for C2-C9 alkanes set by NASA in 2008 under the guidance and approval of the National Research Council specifically excluded SMACs for n-hexane. Unlike other C2-C9 alkanes, n-hexane can cause polyneuropathy after metabolism in humans or rodents and so requires more stringent SMACs than the other members of this group do. This document reviews the relevant published studies of n-hexane toxicity to develop exposure duration-specific SMACs for n-hexane of 200 ppm for 1 hour, 30 ppm for 24 hours, and 2.4 ppm for 7 days, 30 days, 180 days, and 1000 days.Garcia HD. Acceptable limits for n-hexane in spacecraft atmospheres. Aerosp Med Hum Perform. 2021; 92(12):956–961.

Multiomics Provide Insights into the Key Molecules and Pathways Involved in the Physiological Adaptation of Atlantic Salmon (Salmo salar) to Chemotherapeutic-Induced Oxidative Stress

Although chemotherapeutics are used to treat infections in farmed fish, knowledge on how they alter host physiology is limited. Here, we elucidated the physiological consequences of repeated exposure to the potent oxidative chemotherapeutic peracetic acid (PAA) in Atlantic salmon (Salmo salar) smolts. Fish were exposed to the oxidant for 15 (short exposure) or 30 (long exposure) minutes every 15 days over 45 days. Unexposed fish served as the control. Thereafter, the ability of the remaining fish to handle a secondary stressor was investigated. Periodic chemotherapeutic exposure did not affect production performance, though survival was lower in the PAA-treated groups than in the control. Increased ventilation, erratic swimming, and a loss of balance were common behavioural manifestations during the oxidant exposure. The plasma reactive oxygen species levels increased in the PAA-treated groups, particularly after the third exposure, suggesting an alteration in the systemic oxidative stress status. Plasma indicators for internal organ health were affected to a certain degree, with the changes mainly observed after the second and third exposures. Metabolomics disclosed that the oxidant altered several circulating metabolites. Inosine and guanosine were the two metabolites significantly affected by the oxidative stressor, regardless of exposure time. A microarray analysis revealed that the gills and liver were more responsive to the oxidant than the skin, with the gills being the most sensitive. Moreover, the magnitude of the transcriptomic modifications depended on the exposure duration. A functional analysis showed that genes involved in immunity and ribosomal functions were significantly affected in the gills. In contrast, genes crucial for the oxidation-reduction process were mainly targeted in the liver. Skin mucus proteomics uncovered that the changes in the mucosal proteome were dependent on exposure duration and that the oxidant interfered with ribosome-related processes. Mucosal mapping revealed gill mucous cell hypertrophy after the second and third exposures, although the skin morphological parameters remained unaltered. Lastly, repeated oxidant exposures did not impede the ability of the fish to mount a response to a secondary stressor. This study provides insights into how a chemical oxidative stressor alters salmon physiology at both the systemic and mucosal levels. This knowledge will be pivotal in developing an evidence-driven approach to the use of oxidative therapeutics in fish, with some of the molecules and pathways identified as potential biomarkers and targets for assessing the physiological cost of these treatments.

The temporal pattern of VR sickness during 7.5-h virtual immersion

In this study, we assessed the relationship between exposure duration and VR sickness severity during 7.5-h virtual immersion. First, we showed that the VR sickness severity was positively correlated to the exposure duration: the longer participants were exposed to the VR environment, the more severe sickness symptoms they had. Second, we showed a dynamic sickness adaptation process during a long time of VR exposure: the sickness adaption effect that had already been established could be broken as the exposure duration continued to increase, and a new sickness adaption process would establish. Moreover, we showed a distinguishable symptom profile of HMD compared with LCD, which was insusceptible of exposure duration. This is the first report presenting the temporal pattern of VR sickness during such long-duration exposure. Our study could offer a predictive model of VR sickness severity level during long virtual immersion and provide suggestions for the use of VR technology for scientific study, clinical application, and business entertainment.

Evolution of Passivity for the Multi-Principal Element Alloy CoCrFeNi with Potential, pH and Exposure in Chloride Solution

The evolution of passivity of the multi-principal element alloy CoCrFeNi was studied as a function of potential, pH and exposure duration in 0.1 M NaCl. It was shown that CoCrFeNi exhibits excellent passivity irrespective of pH, revealing a multi-oxide passive film enriched with Cr(III) oxide. Electrochemical impedance spectroscopy suggests that the passive film thickness and polarisation resistance increase with pH and exposure duration, whereby the growth behavior of the passive film was consistent with the assumptions of the point defect model. X-ray photoelectron spectroscopy analysis suggested that the fraction of Co(II) and Ni(II) oxides in the passive film, and their contributions to the passivity of the alloy, increased with increase in pH of the electrolyte. The present work explores the complex synergy between composition, thermodynamics and kinetics on the resultant passivity of a multi-principal element alloy.

Hygienic Assessment of Disposable Baby Diapers Made with Innovative Materials

Background: It is of current importance to develop an algorithm for assessing chemical and physical safety of products for children and adolescents made with such innovative materials as organic cotton, bamboo, fibers and threads containing silver ions used for children’s underwear, materials impregnated with marigold extract for insoles of children’s footwear, and diapers from plant raw materials. The institute conducts testing and scientific substantiation of children’s goods made using innovative technologies. Objective: To assess safety of diapers made with innovative materials (ECO-diapers). Materials and methods: We conducted physicochemical, toxicological and organoleptic testing of 200 samples of medium size disposable baby ECO-diapers made with innovative materials. Results: The results of chemical and toxicological tests of ECO-diapers in a model aqueous environment showed that the formaldehyde concentration in aqueous extracts of the diaper samples ranged from 0.08 ± 0.020 to 0.1 mg/dm3; toxicity index values – from 74.1 to 89.1 %; pH – from 0.35 to 0.5 units, and the total phenolic content – from < 0.005 to 0.024 ± 0.002 mg/dm3, thus being within permissible limits. Measured concentrations of acetaldehyde, acrylonitrile, acetone, benzene, hexane, methyl and propyl alcohols, toluene, ethyl acetate, lead, arsenic, zinc, chromium were also below threshold values. Chemical testing of the samples of baby diapers in a model air environment with exposure duration of 4, 12, and 24 hours detected migration of chemicals already after four hours of exposure, which did not change following 12 and 24 hours. The value of water absorption capacity, which is one of the main indicators of functional benefit of diapers, ranged from 307.6 ± 30.8 g to 355.5 ± 35.5 g and significantly exceeded the established standard (not less than 240.0 g for medium size diapers) owing to the use of innovative materials in the production of ECO-diapers. Conclusions: Our findings demonstrate the necessity to develop special methodological approaches to measuring breathability of ECO- and traditional diapers, to regulate smell by including this organoleptic quality criterion in the list of safety requirements, and to limit exposure duration in a model air environment to four hours.

Effects of Soil Temperature and Moisture on the Development and Survival of Grasshopper Eggs in Inner Mongolian Grasslands

Grasshopper eggs overwinter in soil for almost half a year. Changes in soil temperature and moisture have a substantial effect on grasshopper eggs, especially temperature and moisture extremes. However, the combinatorial effect of temperature and moisture on the development and survival of grasshopper eggs has not been well studied. Here, we examined the effects of different soil moistures (2, 5, 8, 11, 14% water content) at 26°C and combinations of extreme soil moisture and soil temperature on the egg development and survival of three dominant species of grasshopper (Dasyhippus barbipes, Oedaleus asiaticus, and Chorthippus fallax) in Inner Mongolian grasslands. Our data indicated that the egg water content of the three grasshopper species was positively correlated with soil moisture but negatively correlated with hatching time. The relationship between hatching rate and soil moisture was unimodal. Averaged across 2 and 11% soil moisture, a soil temperature of 35oCsignificantly advanced the egg hatching time of D. barbipes, O. asiaticus, and C. fallax by 5.63, 4.75, and 2.63 days and reduced the egg hatching rate of D. barbipes by 18%. Averaged across 26 and 35°C, 2% soil moisture significantly delayed the egg hatching time of D. barbipes, O. asiaticus, and C. fallax by 0.69, 11.01, and 0.31 days, respectively, and decreased the egg hatching rate of D. barbipes by 10%. The hatching time was prolonged as drought exposure duration increased, and the egg hatching rate was negatively correlated with drought exposure duration, except for O. asiaticus. Overall, the combination of high soil temperature and low soil moisture had a significantly negative effect on egg development, survival, and egg hatching. Generally, the response of grasshopper eggs to soil temperature and moisture provides important information on the population dynamics of grasshoppers and their ability to respond to future climate change.

Stationary Soil Steaming to Combat Invasive Plant Species for Soil Relocation

Eradication of alien invasive species in the soil with steam as an alternative to chemical fumigation may allow contaminated soil to be reused. We have investigated steam disinfestation of soil to combat invasive plant species in three experiments including different temperatures and exposure durations using a stationary soil steaming prototype device. The experiments included effects on seed germination of Lupinus polyphyllus (LUPPO), Impatiens glandulifera (IPAGL), and Avena fatua (one population from Poland AVEFA(P) and one from Norway AVEFA(N)), as well as effects on sprouting rhizome fragments of Solidago canadensis (SOOCA) and Reynoutria x bohemica (REYBO). In the first experiment (i) we tested four different soil temperatures of 64, 75, 79 and 98°C with an exposure duration of 90 s. In the second and third experiments we tested exposure durations of (ii) 30, 90 and 180 s and (iii) 90, 180 and 540 s, respectively, at 98°C. Seed pre-treatment of 14 days cooling for LUPPO and IPAGL, no seed pre-treatment and 12 h moistening for AVEFA populations, and 5 and 10 cm cutting size for REYBO were applied. Our results showed germination/sprouting was inhibited at 75°C for I. glandulifera (for 90 s) and 98°C for the other species; however, longer exposure duration was needed for L. polyphyllus. While 30 s at 98°C was enough to kill A. fatua seeds and S. canadensis and R. x bohemica rhizome fragments, 180 s exposure duration was needed to kill L. polyphyllus seeds. The results showed promising control levels of invasive plant propagules in contaminated soil by steaming, supporting the steam treatment method as a potential way of soil disinfection to avoid dispersal of invasive species.