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Poás Volcano made a magmatic eruption in April 2017. The volcanic outburst resulted in an ash and vapor column towering over three kilometers high. Since that time, there has been a continual release of gases, aerosols, and more recently, ash, posing potential issues for visitors and park rangers. In this work, the potential for exposure to acid gases and aerosols faced by park rangers, officials, and visitors to the Poás Volcano National Park was evaluated, and the concentrations found were compared with the exposure limits established by the Occupational Safety and Health Administration (OSHA). The study was conducted between October 2021 and November 2022. the concentrations of HCl(g), HNO3(ac), HF(g), and H2SO4(ac) were determined at three strategic points: the ranger station, the visitor center, and the main crater viewpoint. The maximum concentrations obtained were (7.0 ± 1.6) ppb for HCl(g), (6.2 ± 2.8) ppb for HNO3(ac), and (0.029 ± 0.044) ppm for H2SO4(ac). There were no concentration values above the detection limit (0.94 μg/m3) for HF(g). By comparing the data obtained with similar studies, it is concluded that the measured values in Poás Volcano National Park are low and only show similarities to the results found in volcanoes within the national territory. The exposure limit established by OSHA (0.02 ppm) was only surpassed by H2SO4(ac), and could be the cause of health effects experienced over the years by park rangers. To minimize these risks, the use of personal protective equipment and air quality monitoring is essential. [ABSTRACT FROM AUTHOR]

The Partner Agencies of the International Space Station (ISS) maintain separate career exposure limits and shared Flight Rules that control the ionising radiation exposures that crewmembers can experience due to ambient environments throughout their space missions. In low Earth orbit as well as further out in space, energetic ions referred to as galactic cosmic radiation (GCR) easily penetrate spacecraft and spacecraft contents and consequently are always present at low dose rates. Protons and electrons that are trapped in the Earth’s geomagnetic field are encountered intermittently, and a rare energetic solar particle event (SPE) may expose crew to (mostly) energetic protons. Space radiation protection goals are to optimize radiation exposures to maintain deleterious late effects at known and acceptable levels and to prevent any early effects that might compromise crew health and mission success. The conventional radiation protection metric effective dose provides a basic framework for limiting exposures associated with human spaceflight and can be communicated to all stakeholders. Additional metrics and uncertainty analyses are required to understand more completely and to convey nuanced information about potential impacts to an individual astronaut or to a space mission. Missions to remote destinations well beyond low Earth orbit (BLEO) are upcoming and bestow additional challenges that shape design and radiation protection needs. NASA has recently adopted a more permissive career exposure limit based upon effective dose and new restrictions on mission exposures imposed by nuclear technologies. This manuscript reviews the exposure limits that apply to the ISS crewmembers. This work was performed in collaboration with the advisory and guidance efforts of International Commission on Radiological Protection (ICRP) Task Group 115 and will be summarized in an upcoming ICRP Report.

The Partner Agencies of the International Space Station (ISS) maintain separate career exposure limits and shared Flight Rules that control the ionising radiation exposures that crewmembers can experience due to ambient environments throughout their space missions. In low Earth orbit as well as further out in space, energetic ions referred to as galactic cosmic radiation (GCR) easily penetrate spacecraft and spacecraft contents and consequently are always present at low dose rates. Protons and electrons that are trapped in the Earth's geomagnetic field are encountered intermittently, and a rare energetic solar particle event (SPE) may expose crew to (mostly) energetic protons. Space radiation protection goals are to optimize radiation exposures to maintain deleterious late effects at known and acceptable levels and to prevent any early effects that might compromise crew health and mission success. The conventional radiation protection metric effective dose provides a basic framework for limiting exposures associated with human spaceflight and can be communicated to all stakeholders. Additional metrics and uncertainty analyses are required to understand more completely and to convey nuanced information about potential impacts to an individual astronaut or to a space mission. Missions to remote destinations well beyond low Earth orbit (BLEO) are upcoming and bestow additional challenges that shape design and radiation protection needs. NASA has recently adopted a more permissive career exposure limit based upon effective dose and new restrictions on mission exposures imposed by nuclear technologies. This manuscript reviews the exposure limits that apply to the ISS crewmembers. This work was performed in collaboration with the advisory and guidance efforts of International Commission on Radiological Protection (ICRP) Task Group 115 and will be summarized in an upcoming ICRP Report. [ABSTRACT FROM AUTHOR]

The United States has witnessed a concerning surge in the incidence of diseases like Coal Workers' Pneumoconiosis (CWP), despite numerous efforts aimed at prevention. This study delves into the realm of respiratory health by investigating the deposition of dust particles within the respiratory tract and lungs. By analyzing particles of varying sizes, shapes, velocities, and aerodynamic diameters, we aim to gain a comprehensive understanding of their impact on deposition patterns. This insight could potentially drive changes in dust exposure protocols within mining environments and improve monitoring practices. The interplay of several critical factors, including particle characteristics and an individual's breathing patterns, plays a pivotal role in determining whether particles settle in the lungs or are exhaled. This paper provides a comprehensive literature review on Respirable Coal Mine Dust (RCMD), with a specific focus on examining particle deposition across different regions of the airway system and lungs. Additionally, we explore the utility of Computational Fluid Dynamics (CFD) in simulating particle behavior within the respiratory system. Predicting the precise behavior of dust particles within the respiratory airway poses a significant challenge. However, through numerical simulations, we aspire to enhance our understanding of strategies to mitigate total lung deposition by comprehensively modeling particle interactions within the respiratory system. [ABSTRACT FROM AUTHOR]

Abstract In the late-1990s, the FCC and ICNIRP adopted radiofrequency radiation (RFR) exposure limits to protect the public and workers from adverse effects of RFR. These limits were based on results from behavioral studies conducted in the 1980s involving 40–60-minute exposures in 5 monkeys and 8 rats, and then applying arbitrary safety factors to an apparent threshold specific absorption rate (SAR) of 4 W/kg. The limits were also based on two major assumptions: any biological effects were due to excessive tissue heating and no effects would occur below the putative threshold SAR, as well as twelve assumptions that were not specified by either the FCC or ICNIRP. In this paper, we show how the past 25 years of extensive research on RFR demonstrates that the assumptions underlying the FCC’s and ICNIRP’s exposure limits are invalid and continue to present a public health harm. Adverse effects observed at exposures below the assumed threshold SAR include non-thermal induction of reactive oxygen species, DNA damage, cardiomyopathy, carcinogenicity, sperm damage, and neurological effects, including electromagnetic hypersensitivity. Also, multiple human studies have found statistically significant associations between RFR exposure and increased brain and thyroid cancer risk. Yet, in 2020, and in light of the body of evidence reviewed in this article, the FCC and ICNIRP reaffirmed the same limits that were established in the 1990s. Consequently, these exposure limits, which are based on false suppositions, do not adequately protect workers, children, hypersensitive individuals, and the general population from short-term or long-term RFR exposures. Thus, urgently needed are health protective exposure limits for humans and the environment. These limits must be based on scientific evidence rather than on erroneous assumptions, especially given the increasing worldwide exposures of people and the environment to RFR, including novel forms of radiation from 5G telecommunications for which there are no adequate health effects studies.

Human milk is the healthiest option for newborns, although, under specific circumstances, infant formula is a precious alternative for feeding the baby. Except for the nutritional content, infant formulas and baby food must be pollutant-free. Thus, their composition is controlled by continuous monitoring and regulated by establishing upper limits and guideline values for safe exposure. Legislation differs worldwide, although there are standard policies and strategies for protecting vulnerable infants. This work presents current regulations and directives for restricting endocrine-disrupting chemicals and persistent organic pollutants in infant formulas. Risk assessment studies, which are limited, are necessary to depict exposure variations and assess the health risks for infants from dietary exposure to pollutants. [ABSTRACT FROM AUTHOR]

Of particular interest within fifth generation (5G) cellular networks are the typical levels of radiofrequency (RF) electromagnetic fields (EMFs) emitted by 'small cells', low-power base stations, which are installed such that both workers and members of the general public can come in close proximity with them. In this study, RF-EMF measurements were performed near two 5G New Radio (NR) base stations, one with an Advanced Antenna System (AAS) capable of beamforming and the other a traditional microcell. At various positions near the base stations, with distances ranging between 0.5 m and 100 m, both the worst-case and time-averaged field levels under maximized downlink traffic load were assessed. Moreover, from these measurements, estimates were made of the typical exposures for various cases involving users and non-users. Comparison to the maximum permissible exposure limits issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) resulted in maximum exposure ratios of 0.15 (occupational, at 0.5 m) and 0.68 (general public, at 1.3 m). The exposure of non-users was potentially much lower, depending on the activity of other users serviced by the base station and its beamforming capabilities: 5 to 30 times lower in the case of an AAS base station compared to barely lower to 30 times lower for a traditional antenna. [ABSTRACT FROM AUTHOR]

The verification of the limits of the population’s exposure to the magnetic field generated by double-circuit power lines from field measurements carried out on site is not trivial. It requires knowledge of the power line current instant values during the measurement period, the determination of the relationship between current and field at the measurement points (made more complex by the double-circuit overhead line configuration) and the use of that relationship to extrapolate the field values. Nevertheless, the verification of exposure limits for double-circuit power lines from on-site measurements is often conducted with rough, or not particularly stringent, procedures. A practical and straightforward procedure of general validity for non-optimized double-circuit lines is proposed here. No specific measurement position or conductors disposition knowledge is required as well as no complex three-dimensional finite element method code is necessary. The procedure, potentially also applicable to high- and extra-high-voltage lines, is validated on a medium-voltage (15 kV) double-circuit overhead power line study case. Exposure limits assessment suggests that if the line is operated at its rated capacity (230/285 A), the 3 μT quality target is missed. Results are provided with a 95% confidence interval ranging from ±100 nT to ±140 nT in all the cases.

A FAVORABLE COMPARISON WITH AIRCRAFT-SPECIFIC LIMITS DOES NOT ASSURE ACCEPTABILITY Chen et al. suggest that the favorable comparison of aircraft data to aircraft design standards implies acceptability. 5 The aircraft limit should be lower than that for ground-based applications; because, in operation, the aircraft environment is reduced pressure, which increases susceptibility to hypoxia. Keywords: air quality; aircraft; exposure limits; fumes; marker compounds; thermal environment EN air quality aircraft exposure limits fumes marker compounds thermal environment 1 4 4 03/02/22 20220201 NES 220201 CONFLICTS OF INTEREST The author is employed in the safety, health, and security department of a union, which represents nearly 50 000 flight attendants at 17 US airlines (Association of Flight Attendants, AFL-CIO). It is understandable that they did not cite a UFP limit in table 1 because there are no such limits currently, whether on or off aircraft.13 Notably, though, a World Health Organization guideline defines a count of >20 000 particles/cm SP 3 sp (1 h mean) as "high",14 which is considerably lower than some of the aircraft data. [Extracted from the article]

Maximum power extrapolation techniques from measured data are usually employed to assess the compliance with standards of average fields radiated by base stations. However, such techniques provide an upper bound, which is not reached in real scenarios. This is particularly true in 5G Communications, where Active Antenna Systems allow a decrease of the average power density according to the adopted scheduling strategy. This paper is focused on the power reduction estimation in realistic scenarios. In particular a deterministic model of a communication system is used to obtain simple formulas only requiring the knowledge of the served area angular extension and of the Envelope Radiation Pattern of the antenna. The model, developed for beam steering and grid of beams antennas, is also extended to analyze the case of Multi User massive Multiple Input Multiple Output (MU-mMIMO) antennas with single layer per user, showing that under proper hypothesis on the beams of the antenna it is possible to estimate the reduction parameter without the explicit knowledge of the number of layers of MU-mMIMO systems. In spite of the simplicity of the approach, comparison with stochastic models and results reported in recent literature show that the formulas obtained using the model proposed in this paper allow to obtain a useful approximation of the power reduction factor, making the formulas suitable for a preliminary fast estimation of the Electromagnetic Field in 5G cells for human exposure assessment.

In this contribution, we focus on the exposure limits and compliance distances of 5G communication systems based on large antenna arrays with high gain and multiplexing capability. In particular, starting from the observation that the antenna array continuously changes its radiation pattern to communicate with a number of user terminals, we develop a simple approach for evaluating a reliable but not overly conservative boundary for the fields radiated by the antenna array. This approach is based on the use of the Normalized Average Power Pattern, and through the paper we show its behavior and demonstrate its usefulness in some cases of interest. Finally, the obtained results are validated by means of an electromagnetic simulation of the antenna and the propagation scenario, that is achieved by means of a ray-launching code.

This study examines thermal responses of skin to pulsed millimeter wave (mm-wave) and radiofrequency (RF) radiation. We review limits for pulse fluence in the IEEE Std. C95.1-2019 and the 2020 guideline of the International Commission on Nonionizing Radiation Protection (ICNIRP), as well as the recently re-affirmed guidelines of the U.S. Federal Communications Commission (FCC). The focus of the study is on millimeter-wave frequencies (30-300 GHz) where energy is absorbed close to the body surface and intense pulses could potentially cause high temperature gradients at the skin, but the model is extended to lower frequencies as well. The study employs a simple one-dimensional baseline thermal model for skin and Pennes' bioheat equation (BHTE), together with a baseline model for thermal damage to skin based on a standard model. The predicted temperature increases produced by 3-sec pulses at 94 GHz are consistent with previous experimental results with no adjustable parameters in the model. The few reported data on thermal damage to the skin from pulsed 94 GHz energy are insufficient to enable a conventional analysis of damage thresholds and the data may be affected by errors in dosimetry. The baseline model suggests that the implicit limits on pulse fluence in the present FCC guidelines might allow, in extreme (but in practice unrealistic) cases, transient increases in skin temperature that approach thresholds for thermal pain but which remain well below levels anticipated to cause thermal damage. Limits on pulse fluence in the current IEEE and ICNIRP exposure guidelines would preclude such effects. Such extreme pulses are far above those that are emitted by wireless and other technologies but may be emitted by some nonlethal weapons systems. FCC's proposed “device-based time averaging” rules will restrict thermal transients in skin from mm-wave transmitters to levels that are roughly an order of magnitude below the slower temperature increases produced by the low-frequency components of the modulation waveform and appear to be excessively conservative. An appendix discusses the applicability of two approximations to the analytical solutions to the bioheat equation that can be used to estimate temperature increases in skin from exposure to mm-waves.

The study assessed potential to exceed occupational exposure limits while spraying paint with and without a silver nanoparticle biocidal additive. A tradesperson performed the tasks in a sealed chamber with filtered air supply. Integrated air sampling entailed transmission electron microscopy with energy dispersive X-ray analysis, direct-reading of particle number concentrations, and determination of silver mass concentration by NIOSH Method 7300. Silver nanoparticles were primarily embedded in paint spray droplets but also observed as isolated particles. Using an α-level of 0.05, median nanoparticle number concentrations did not differ significantly when spraying conventional vs. biocidal paint, although statistically significant differences were observed at specific particle size ranges <100 nm. The geometric mean concentration of total silver while spraying biocidal paint (n = 6) was 2.1 µg/m3 (95% CI: 1.5–2.8 µg/m3), and no respirable silver was detected (<0.50 µg/m3). The results address a lack of silver nanoparticle exposure data in construction and demonstrate the feasibility of a practical sampling approach. Given similar conditions, the measurements suggest a low probability of exceeding a proposed silver nanoparticle exposure limit of 0.9 µg/m3 as an airborne 8-hr time-weighted average respirable mass concentration. A full workday of exposure to respirable silver at the highest possible level in this study (<0.50 µg/m3) would not exceed the exposure limit, although limitations in comparing short task-based exposures to an 8-hr exposure limit must be noted. There was airflow in the study chamber, whereas exposure levels could increase over time in work environments lacking adequate ventilation. Potential to exceed the exposure limit hinged upon the respirable fraction of the paint mist, which could vary by material and application method. Additional research would improve understanding of silver nanoparticle exposure risks among construction trades, and biological responses to these exposures. Given the potential for exposure variability on construction jobsites, safety and health professionals should be cognizant of methods to assess and control silver nanoparticle exposures. [ABSTRACT FROM AUTHOR]

Background: CONTEXT Intraoperative three-dimensional (3D) computed tomography (CT) imaging has become increasingly popular in spine surgery. Previous spine surgeon radiation exposure research has focused largely on procedures using fluoroscopy, however, few studies have been performed on the subject since the introduction of the 3D imaging systems. As a result, concerns have re-emerged over surgeon radiation exposure and the effectiveness of operating room (OR) protocols for decreasing workplace radiation. Current radiation safety guidelines require surgeons wear full body protective lead while any type of radiation is being administered during surgery. As a result, local institutions do not allow for the use of free-standing lead shields for sole radiation protection in the operating room. However, there is no data available to demonstrate whether the additional personal lead is required, or if in fact the lead shield alone is sufficient.Purpose: This study investigated the effectiveness of a free-standing lead shield in reducing spine surgeon radiation exposure in the operating room during intraoperative imaging.Study Design/setting: A prospective clinical research study at a large, tertiary care center.Patient Sample: Twenty-seven patients undergoing instrumented spinal procedures between June and August 2019.Outcome Measures: Fluoroscopy time, total fluoroscopy dose delivered, 3D dose delivered, total 3D spins, number of HD spins, number of standard spins, number of fluoroscopic images, number of spine levels operated on, patient size setting, shield distance from patient, radiation dose in front of shield, radiation dose behind shield.Methods: Twenty-seven instrumented spinal procedures using the O-Arm Imaging System (Medtronic, Minneapolis, MN) were observed to determine radiation exposure to a spine surgeon standing behind a lead shield in the OR. Two thermoluminescent dosimeters were used to measure scatter radiation in front of and behind lead shields. Both fluoroscopy and intraoperative CT based radiation exposure was recorded. The dosimeter readings were compared to determine the degree of radiation attenuation by the lead shield. Regression analysis of the exposure values from behind the shield, shield distance from the patient, and radiation dose delivered by the imaging system was utilized to estimate the number of cases required to surpass annual exposure limits. Case numbers were calculated for the highest "worst case" and "average case" exposure values. The safe annual occupation exposure limit determined by the National Council on Radiation Protection is five roentgen equivalent man (rem) or 50,000 microsieverts (μSv).Results: Average surgeon radiation exposure per case was 0.694 μSv (SD: 0.501, Range: 0.105-2.167) behind the lead shield compared to 14.577 μSv (SD: 9.864, Range: 2.185-44.492) in front of the lead shield. The average radiation dose reduction by the lead shield was 13.962 μSv (SD: 9.49, Range: 2.08-42.72) per case, which is equivalent to an average of 95.65% (SD: 1.71) radiation attenuation by lead shielding. If surgeons stand behind lead shields in the OR, the annual number of 3D image-guided spinal procedures required to surpass exposure limits is 15,479 and 67,060 based on "worst case" and "average case" analyses, respectively.Conclusions: Our study demonstrates standing behind intraoperative lead shields is very effective at decreasing radiation exposure to surgeons. Additionally, surgeon radiation doses behind lead shielding fall far below annual exposure limits. Surgeons should not need additional protective equipment when a lead shield is used. [ABSTRACT FROM AUTHOR]

This paper considers the problem of choosing an appropriate “averaging time” in radiofrequency (RF) exposure limits to protect against thermal hazards, focusing on the RF frequency range above 3-10 GHz. Analysis is based on examination of the dynamic properties of thermal models for tissue using Pennes' bioheat equation. Three models are considered: a baseline model consisting of a uniform half space with dielectric and thermal properties similar to those of human skin with adiabatic boundary conditions; a layered 1D model with dielectric and thermal properties similar to those of skin, fat, and underlying muscle, with convective boundary conditions appropriate for room environments; and exposures to the head of an anatomically detailed image-based model (“Taro”). RF exposure consisted of plane wave radiation incident on the two planar models, and radiation from resonant dipoles located 1.5 cm from the head model, at frequencies ranging from 1 to 300 GHz. The dynamic properties of the models were explored by analytic solution of the baseline model, and from numerical solutions of the thermal responses of the layered and head models. From the step responses of the models (increases in surface temperature to a suddenly imposed exposure), the impulse and frequency responses of the models were obtained. In the frequency domain, the thermal models exhibit extreme lowpass characteristics with cutoff (-3 dB response) frequencies below 1 mHz. The impulse response to millimeter wave radiation (30-300 GHz) shows a sharp peak at zero time, due to short term accumulation of heat near the surface, which dissipates quickly as heat is conducted into deeper layers of tissue. Simple analytical results of a further simplified model assuming purely surface heating agree well with results of a more detailed assessment for millimeter waves. Response of the model to pulse trains and to single maximum fluence “big bang”pulses in which all allowable energy over a 6-min averaging time is delivered in one short pulse raises the possibility of excessive transient temperature increases at the tissue surface from exposure to short high-fluence pulses at mm-wave frequencies. Such exposures are not produced by current technologies apart from certain military weapons systems but may occur from future high-power mm-wave technology. By contrast, simulations of exposure from a communications waveform at 1.9 GHz show extremely tiny transient temperature fluctuations. The results generally confirm the present choice of 6 min for an averaging time in the current generation of RF exposure limits but suggest the need for additional limits on fluence for brief high-fluence pulses at mm-wave frequencies. This paper addresses thermal hazards only, and a larger range of evidence would need to be evaluated as well in revising exposure limits.

Benzene is a carcinogenic pollutant with significant emission sources present in the atmosphere. The need for accurate and precise measurement of benzene in the atmosphere has become increasingly evident due to its toxicity and the adverse health effects associated with exposure to different concentrations. Certified reference material (CRM) is essential to establish the traceability of measurement results. The present review compiles the available national and international measurement methods, certified reference materials (CRMs) for benzene and the limit of benzene in fuel composition (v/v) worldwide. Overall, the review indicates the benzene level in the atmosphere and the resulting impacts on the environment and human health, which frequently exceed the exposure limits of different environment regulatory agencies. An extensive literature review was conducted to gather information on monitoring and analysis methods for benzene, revealing that the most preferred method, i.e. Gas Chromatography- Flame Ionization Detector and Mass Spectrometry, is neither cost-effective nor suitable for real-time continuous monitoring. By analysing existing literature and studies, this review will shed light on the understanding of the importance of benzene pollution monitoring in ambient air and its implications for public health. Additionally, it will reflect the mitigation strategies applied by regulators & need for future revisions of air quality guidelines.

Featured Application: The developed software facilitates the quick calculation of magnetic flux density produced by electric current in facilities in whichever conditions, which can be used to detect inadmissible levels of immission and to propose design improvements. The World Health Organization (WHO) warns that the presence of magnetic fields due to the circulation of industrial frequency electrical currents may have repercussions on the health of living beings. Hence, it is crucially important that we are able to quantify these fields under the normal operating conditions of the facilities, both in their premises and in their surroundings, in order to take the appropriate corrective measures and assure the safety conditions imposed, in force, by regulations. For this purpose, CRMag® software has been developed. Using the simplified Maxwell equations for low frequencies, CRMag® calculates and represents the magnetic flux density (MFD) that electrical currents produce in the environment. Users can easily model electrical facilities through a friendly and simple data entry. MFDs calculated by CRMag® have been validated in real facilities and laboratory tests. With this software, exposure levels can be studied in any hypothetical scenario, even in inaccessible zones. This allows designers to guarantee that legal limits (occupational, general population, or precautionary levels related to epidemiological studies) are fulfilled. A real case study has been described to show how the reconfiguration of conductors in a distribution transformer substation (DTS) allows significant reductions in MFD in some points outside the facility. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Exposure to excess manganese (Mn) can cause multiple toxicological outcomes in humans, most notably neurotoxicity. Ample epidemiological evidence suggests that chronic, low-level exposure causes subclinical cognitive effects. Because NASA astronauts will be exposed to Mars regolith. Spacecraft Maximum Allowable Concentrations (SMACs) were developed following an extensive literature review. METHODS: Multiple databases were searched for information relevant to derivation of Mn SMAC values. An additional search for Mars dust data was performed. Risk assessment approaches were applied, including adjustments for space-relevant susceptibility to Mn effects, to develop limits for 1-h to 1000-d exposures. Rover data informed the assessment and enabled calculation of allowable total dust exposure based on Mn content. RESULTS: Over 400 relevant sources were identified. Applicability of exposure characteristics and data collection methods influenced key study choice. SMACs ranging from 3 mg⋅m-3 (1 h) - 0.0079 mg⋅m-3 (1000 d) were set to protect primarily against neurocognitive and respiratory effects. Considering 0.38 wt% total Mn presence in the dust, maximum recommended total dust exposure should not exceed 790 mg⋅m-3 (1 h) - 2 mg⋅m-3 (1000 d). DISCUSSION: This literature review allowed for identification of relevant studies to inform SMAC development. Manganese is one of several components to consider when developing an appropriate total dust limit for Martian dust; other dust elements may alter Mn bioavailability. Mission-specific activities may require alteration of assumptions regarding Mn dust concentration and exposure duration. However, based on expected toxicity of particulate matter itself, the acute SMACs are protective, even with transient exposure during activities that could produce higher concentrations. [ABSTRACT FROM AUTHOR]

As a high production volume chemical with recognized sensory irritation and widespread exposure, the human health risk potential of formaldehyde has been reviewed by many international regulatory agencies and scientific advisory bodies. A scientific panel, the Human Studies Review Board, under the auspices of the EPA's Toxic Substances Control Act (TSCA) program recently reviewed the sensory irritation studies included in the 2022 Draft Integrated Risk Information System (IRIS) Formaldehyde Hazard Assessment in the context of their use in a weight of evidence evaluation of acute inhalation health effects. This panel issued a series of recommendations on the use of these studies for the purposes of calculating exposure limits (e.g., study design preferences; uncertainty adjustment). Considering that these recommendations might reflect topic areas with varying degrees of scientific consensus, this commentary reflects on commonalities and distinctions amongst international formaldehyde exposure limits based on sensory irritation. Notably, each review panel charged with an assessment of the science recommended that no adjustment was needed to account for either exposure duration or human variability. These areas of scientific consensus should be considered as the best available science for the purposes of setting exposure limits in the anticipated TSCA Risk Evaluation on formaldehyde. • Formaldehyde short-term exposure limits often protect against sensory irritation. • Scientific panels consistently recommend no adjustment for exposure duration. • Scientific panels consistently recommend no adjustment for human variability. • Scientific consensus should be considered in the upcoming TSCA Risk Evaluation. [ABSTRACT FROM AUTHOR]

The results of a computer simulation examining the compliance of a given transcranial magnetic stimulation device to the 2010 International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines are presented. The objective was to update the safe distance estimates with the most current safety guidelines, as well as comparing these to values reported in previous publications. The 3D data generated was compared against results available in the literature, regarding the MCB-70 coil by Medtronic. Regarding occupational exposure, safe distances of 1.46 m and 0.96 m are derived from the simulation according to the 2003 and 2010 ICNIRP guidelines, respectively. These values are then compared to safe distances previously reported in other studies.

Background: MIRUS™ is a device for target-controlled inhalational sedation in the ICU in combination with use of isoflurane, or sevoflurane, or desflurane. The feasibility of this device has recently been proven; however, ICU staff exposure may restrict its application. We investigated ICU ambient room pollution during daily work to estimate ICU personnel exposure while using MIRUS™.Methods: This observational study assessed pollution levels around 15 adult surgical patients who received volatile anaesthetics-based sedation for a median of 11 hours. Measurements were performed by photoacoustic gas monitoring in real-time at different positions near the patient and in the personnel's breathing zone. Additionally, the impact of the Clean Air™ open reservoir scavenging system on volatile agent pollution was evaluated.Results: Baseline concentrations [ppm] during intervention and rest periods were isoflurane c¯mean = 0.58 ± 0.49, c¯max = 5.72; sevoflurane c¯mean = 0.22 ± 0.20, c¯max = 7.93; and desflurane c¯mean = 0.65 ± 0.57, c¯max = 6.65. Refilling MIRUS™ with liquid anaesthetic yielded gas concentrations of c¯mean = 2.18 ± 1.48 ppm and c¯max = 13.03 ± 9.37 ppm in the personnel's breathing zone. Air pollution in the patient's room was approximately five times higher without a scavenging system.Conclusion: Ambient room pollution was minimal in most cases, and the measured values were within or below the recommended exposure limits. Caution should be taken during refilling of the MIRUS™ system, as this was accompanied by higher pollution levels. The combined use of air-conditioning and gas scavenging systems is strongly recommended. [ABSTRACT FROM AUTHOR]

Background: To protect crewmember health, the U.S. Navy sets exposure limits for more than 200 components of submarine atmospheres. The addition of females to nuclear submarines required a reevaluation of these exposure limits, originally established for all‐male crews. In the case of carbon dioxide (CO2), the only available data suitable for deriving an exposure limit were from a 2010 study sponsored by the British Royal Navy that reported a debatable interpretation casting doubt on whether current U.S. Navy exposure limits served to protect fetal developmental health. Methods: About 120 time‐mated female Sprague–Dawley rats (Crl: CD[SD]) were exposed to CO2 at levels of 1.5%, 2.0%, 2.5%, and 3.0% from gestation days 6 to 20. Dams were euthanized and fetuses were examined. Results: Findings with implications for exposure limits for CO2 during pregnancy were an increased mean litter proportion of early resorptions and a lower mean litter proportion of viable fetuses in the 3.0% CO2 group. Conclusion: The results yield a No Observed Adverse Effect Level (NOAEL) of 2.5% and a Lowest Observed Adverse Effect Level (LOAEL) of 3.0%. The results reasonably allow a point of departure of 2.5% CO2 for deriving an exposure recommendation. An interspecies uncertainty factor was applied to derive a recommended 90‐day continuous exposure limit (CEL) of 0.8% for CO2. As reproductive endpoints that are developmental in nature must be assumed to result from a single exposure at a critical point during gestation, it is further recommended that the 24‐hr emergency exposure limit (EEL) also be 0.8%. [ABSTRACT FROM AUTHOR]

The results of a computer simulation examining the compliance of a given transcranial magnetic stimulation device to the 2010 International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines are presented. The objective was to update the safe distance estimates with the most current safety guidelines, as well as comparing these to values reported in previous publications. The 3D data generated was compared against results available in the literature, regarding the MCB-70 coil by Medtronic. Regarding occupational exposure, safe distances of 1.46 m and 0.96 m are derived from the simulation according to the 2003 and 2010 ICNIRP guidelines, respectively. These values are then compared to safe distances previously reported in other studies. [ABSTRACT FROM AUTHOR]

Background Unlike occupational silica exposures, the association between non-occupational silica exposures and adverse health effects is not well researched, despite its occurrence in communities close to dust-generating sources such as tailings storage facilities (TSFs). Recent studies have shown that communities surrounding TSFs in South Africa often complain about the onset of dust-related health effects. Even though international interim non-occupational crystalline silica limits have been established, South Africa is yet to enforce its own limits for residential areas close to TSF sites. Objective The objective of the study was to assess the need to enforce non-occupational crystalline silica limits for South Africa. Methods The methods involved (1) Quantifying the silica polymorph content in bulk dust collected from TSFs in South Africa; (2) Assessing the possibility of the dust to reach surrounding communities through ambient and personal filter sampling and; (3) Conducting risk characterisation for both cancer and non-cancer endpoints. Results All bulk dust samples consisted mostly of crystalline silica (73.14–87.09%). Large percentages of nanoparticles were identified in all bulk samples (66.8–70.7%) indicating the possibility of the dust to lodge deep within the lungs. The crystalline silica levels obtained from ambient PM 10 sampling and personal PM 4 sampling all exceeded the international crystalline silica interim limits and reached maximum levels of 90 and 50.9 μg·m − 3 , respectively. For three TSFs, sampling sites close to the TSFs showed higher PM 4 silica levels compared to sites further from TSFs. Risk characterisation revealed the possibility of cancer and non-cancer health effects when chronically exposed to silica levels recorded during the study. Conclusion The results indicate unacceptable crystalline silica exposures in surrounding communities and the need for enforcement of an ambient silica limit for South Africa. [ABSTRACT FROM AUTHOR]

This work proposes exposure limits for carbon monoxide in the nuclear submarine environment. Linear and non-linear forms of the Coburn-Foster-Kane equation were used to evaluate carbon monoxide exposure for an environment with low oxygen content, different exposure times and crew physical activity levels. We evaluated the 90-day Continuous Exposure Guidance Level, 24-h and 1-h Emergency Exposure Guidance Levels and 10-day and 24-h Submarine Escape Action Levels. The results showed that the concentration of carbon monoxide in the environment must not exceed 9 ppm for the 90-day Continuous Exposure Guidance Level, 35 ppm for the 24-h Emergency Exposure Guidance Level, 90 ppm 1-h Emergency Exposure Guidance Level, 60 ppm for the 10-day Submarine Escape Action Level and 80 ppm for the 24-h Submarine Escape Action Level. Comparing these values with those established by the National Research Council for the United States Navy, the limits proposed by this work are verified to be lower, which may indicate a risk to the health of the crew. They also show the impact of the crew's level of physical activity on the formation of carboxyhemoglobin. [Display omitted] • Carbon monoxide exposure levels are lower when physical activity is considered. • Physical activity increases carboxyhemoglobin formation for short term exposure. • Linear CFK model showed closer fit to experimental data than the non-linear one. [ABSTRACT FROM AUTHOR]

The pharmaceutical industry is one of the most regulated industries in Switzerland. Though the concept of good manufacturing practises (GMP) was implemented for chemical production in the early 1990s, the rules and regulations for our industry are in constant evolution. In this article we will highlight the impact of these changes to the industry using three recent guideline up-dates as examples: the implementation of ICH Q3D 'Guideline for elemental impurities', the EU-GMP Guideline Part III Chapter 'Guideline on setting health based exposure limits for use in risk identification in the manufacture of different medicinal products in shared facilities' from 01. June 2015, and the new guidelines to data integrity such as 'PIC/S 041-1 Good Practices for Data Management and Integrity in regulated GMP/GDP environments'. These examples show how scientific approaches help to modernize the control strategies for our products and increase product quality for a better patient safety. The requirements of data integrity regulations are also of interest to industries and universities not working under GxP requirements as they also support the business to improve data quality (traceability) for patent applications, and reduce risk of data falsification.

The World Health Organization (WHO) warns that the presence of magnetic fields due to the circulation of industrial frequency electrical currents may have repercussions on the health of living beings. Hence, it is crucially important that we are able to quantify these fields under the normal operating conditions of the facilities, both in their premises and in their surroundings, in order to take the appropriate corrective measures and assure the safety conditions imposed, in force, by regulations. For this purpose, CRMag® software has been developed. Using the simplified Maxwell equations for low frequencies, CRMag® calculates and represents the magnetic flux density (MFD) that electrical currents produce in the environment. Users can easily model electrical facilities through a friendly and simple data entry. MFDs calculated by CRMag® have been validated in real facilities and laboratory tests. With this software, exposure levels can be studied in any hypothetical scenario, even in inaccessible zones. This allows designers to guarantee that legal limits (occupational, general population, or precautionary levels related to epidemiological studies) are fulfilled. A real case study has been described to show how the reconfiguration of conductors in a distribution transformer substation (DTS) allows significant reductions in MFD in some points outside the facility.

High intensity optical radiation can cause damage to the eye and intense radiation in the range of 770-1400 nm can cause thermal retinal damage. In the workplaces where there are high temperature sources, the workers in front of these hot sources without bright light maybe exposed to the intense IR radiation, thus regular measurement of these radiations seems crucial. Measurement of IR radiations by radiometer in specific wavelength ranges is elusive. Moreover, when radiometers are used, the correct application of the recommended exposure limits requires knowledge of spectral radiance which seems sophisticated for hygienists. The main objective of the present study is applying a model to express retinal thermal injury in terms of temperature for molten aluminum ovens in an aluminum foundry that emit optical radiation without visible light. In the proposed model, ACGIH TLVs for retinal thermal injury in the range of 770 to 1400 nm was used where source luminance was under 0.01 cd/cm2. Also, by using the output results of this proposed model it is possible to present a new chart for evaluation of exposure to IR for hot sources based on Threshold Temperature.

A research study was conducted to assess the effectiveness of cool coat in reducing heat strain among workers exposed to heat in a steel plant located in south India. The study consists of assessing heat strain of workers exposed to heat in a steel plant by measuring physiological reactions of workers such as pulse rate and core body temperature with and without cool coat. The coal coat taken for this study was procured from M/s Yamuna Industries, Noida. Out of 140 employees exposed to heat hazard, 101 employees were examined in this study. Study was done in important production units in steel plant having heat hazard. Workers were interviewed and examined and information regarding thermal comfort was collected. First, the heat strain was assessed when the workers were not using cool coats. The air temperature was measured at all hot zone workplaces and found in the range of 34 0 C to 39.4 0 C (Mean: 36.54 0 C & S.D: 1.54). Physiological response such as core body temperature, pulse rate and blood pressure of workers exposed to heat hazard were measured before & after work to know the heat strain sustained by workers when they were working. Maximum core body temperature after work was found to be 39.3 0 C (Mean; 38.52 & S.D; 0.7). Maximum pulse rate of workers after work was found to be 120 beats/minute (Mean; 94.96 beats/minute, S.D: 13.11). The study indicate core body temperature of workers was found more than the permissible exposure limit prescribed by ACGIH, indicating the heat strain sustained by workers is significant, whereas the pulse rate and blood pressure was found normal & not exceeded the limits. Second, with cool coat, the heat strain was assessed among 10 workers selected from the 101 employees. Core body temperature was measured before and soon after work, The core body temperature recorded soon after work was in the range of 35.5 - 37.20C (Mean 36.36, SD= 0.52), indicating a drop in the core body temperature. In this study, a core body temperature rise in the range of 1 0 -1.4 0 C was noticed when the employees were not wearing cool coats. Whereas, with the usage of cool coat a rise in core body temperature was not found and in many coat wearing workers a drop in core body temperature (0.2 to 0.9 0 C) was noticed. Employees revealed that the cool coats was comfortable to use and provided the thermal comforts. The study concluded that the cool coat taken for this study was found effective in reducing the heat strain. [ABSTRACT FROM AUTHOR]

Nanoparticles exist for a long time as both inorganic and organic parts of nature. Recently, massive expansion of nanotechnologies is evidenced, together with intentional production of new nanoparticles which have not been in contact with living organisms until now. Besides obvious positive aspects, potential threats related to their exposure should be taken into consideration. Unique physical-chemical properties of nanoparticles cause a high bioactivity following their intake (through air, ingestion and skin) and unrestricted spread in exposed organs. Primary effects of nanoparticles on cellular level represent oxidative stress and reactions leading to apoptosis, autophagocytosis and necrosis. Number of studies indicating contribution of nanoparticles to numerous disorders has been recently increasing. However, detailed mechanisms of health effects are not well known. Similarly, there is insufficient information on life cycle of nanoparticles in the environment. Research in this field as well as legislation is behind rapid development and use of nanotechnologies. Considering absence of mandatory exposure limits and other protective measures, nanomaterials represent a potential threat for population health. Recommendations and guidelines of international institutions can contribute to deal with situation, however, passing of effective legislation both on national and European level is urgently needed. [ABSTRACT FROM AUTHOR]

In recent years more and more studies have shown that, the low frequency field strength (particularly magnetic, 50 / 60Hz) are a major risk factor; according to some specialists - even more important as the radiation field. As a result, the personnel serving equipment and facilities such as: electric generators, synchronous, the motors, the inverters or power transformers is subjected continually to intense fields, in their vicinity, with possible harmful effects in the long term by affecting metabolism cell, respectively, the biological mechanisms. Therefore, finding new methods and tools for measurement and analysis of low frequency electromagnetic fields may lead to improved standards for exposure limits of the human body. [ABSTRACT FROM AUTHOR]

Technical literature provides numerous studies concerning radiofrequency exposure measurements for various radio communication devices, but there are few studies related to exposure of personnel operating military radio equipment. In order to evaluate exposure and identify cases when safety requirements are not entirely met, both measurements and simulations are needed for accurate results. Moreover, given the technical characteristics of the radio devices used in the military, personnel mainly operate in the near-field region so both measurements and simulation becomes more complex. Measurements were madein situusing a broadband personal exposimeter equipped with two isotropic probes for both electric and magnetic components of the field. The experiment was designed for three different operating frequencies of the same radio equipment, while simulations were made in FEKO software using hybrid numerical methods to solve complex electromagnetic field problems. The paper aims to discuss the comparative results of the measurements and simulation, as well as comparing them to reference levels specified in military or civilian radiofrequency exposure standards. [ABSTRACT FROM PUBLISHER]