Quantitative Exposure Assessment Research Articles

Evaluation and applicability of radiation detectors for quantitative assessment of radiation exposure in a 16-MeV electron UHDR linac

Background and purposeThe investigation of the FLASH effect requires experimental accelerators capable of delivering ultra-high dose rate (UHDR) beams. Rapid widespread use of this technology could be achieved by modifying clinical electron linacs, originally designed to deliver megavoltage photon radiation up to a few Gy per minute to the isocenter, to deliver electron beams at 40 Gy/s and beyond. Only limited experience has been reported on the radiation safety of UHDR electron beams. This work aims to evaluate the performance and applicability of radiation detectors to quantitatively assess the radiation exposure in this context. MethodsA Varian TrueBeam linac has been modified to deliver 16-MeV electron UHDR with dose rates up to 3⋅105 Gy/s (instantaneous) and 256 Gy/s (average) at the isocenter and used to investigate the detectors performances. A short-term survey was performed at the first UHDR beam-on with passive and active detectors. Then, a long-term survey was conducted with passive detectors during the first three months of operation of the UHDR linac. Moreover, linearity of detector response, activation of the linac components and secondary radiation inside the bunker were evaluated. ResultsSelected active survey metres were shown to have a linear response for the detection of the ambient radiation outside the bunker when performing pulsed UHDR irradiations. The most critical locations outside the bunker were identified at the bunker door and at the control room. The results showed that the operation of the linac with a workload limit of 1000 Gy/week at the isocenter would allow respecting a limit of 0.02 mSv/week to the personnel. The activation of the linac head with 16-MeV electron beam was more than ten times greater with conventional beams compared to UHDR. The secondary radiation inside the bunker was also reduced by −27% when employing UHDR beams. ConclusionsThis work provides a comprehensive evaluation of the suitability of active and passive detectors to perform a radiation safety assessment for a 16-MeV electron UHDR linac. The conditions under which commonly available survey metres for photons (FLUKE 451P) and neutrons (Ludlum Model 3007) can safely be employed in controlled areas outside the bunker were investigated. Moreover, we showed that if a radiation vault is safe for 16-MeV electron beams at conventional dose rates, this applies also to UHDR when fixing the linac weekly workload to a given amount of dose at the isocenter.

Quantitative assessment of occupational radiation exposure in CT: a comparative study using two radiation survey meters for year-long dose monitoring of staff

Introduction: Computed Tomography (CT) is crucial in medical imaging but exposes healthcare workers to ionizing radiation. It is essential to quantify and mitigate occupational radiation exposure. This study provides a comprehensive quantitative analysis of CT settings, using two radiation survey meters, over a year-long monitoring period. Methodology: Healthcare workers operating CT scanners were included. Two radiation survey meters, Meter A (GMC-300E, uSv/h) and Meter B (RAR R311516, uSv/h), were used concurrently for continuous measurement and recording of radiation doses. Statistical analysis compared data from both meters and assessed compliance with regulatory limits and quality assurance standards. Results: The study demonstrated excellent consistency in dose measurements between Meter A and Meter B throughout the year, with no statistically significant discrepancies (p≤; 0.05). Cumulative radiation doses of staff remained within legal limits, indicating the efficacy of current safety measures. Conclusion: The study highlights the reliability of Meter A and Meter B for measuring occupational radiation exposure in CT settings. The convergence of results emphasizes their suitability for healthcare settings requiring precise radiation dose monitoring, enhancing radiation safety in CT scanning and protecting healthcare personnel from ionizing radiation exposure.

Assessment of air pollution emitted during cooking using biomass and cleaner fuels in the Shiselweni region of Eswatini (Swaziland)

AbstractIn Eswatini, 62.3% of households still rely on solid fuel for cooking, especially wood (61.8%). Smoke emissions during biomass burning remain the primary source of indoor air pollution, comprising pollutants detrimental to health. This study provides a quantitative exposure assessment of fuels used in the Shiselweni region with the objectives of monitoring the carbon monoxide (CO) and carbon dioxide (CO2) concentrations during cooking events and evaluating cancer and noncancer risks due to exposure to particulate-bound polycyclic aromatic hydrocarbons (PAHs) during cooking events among cooking personnel in households that cook indoors by burning biomass. Real-time CO, CO2, and particulate matter (PM) monitoring was performed in seventeen kitchens during cooking events across the Shiselweni region using different cooking methods: biomass in open fires and stoves, liquefied petroleum gas (LPG), and electric stoves. PM2.5, PM10, and CO exceeded indoor exposure guidelines for biomass fuel-related homesteads. Particulate PAH intake concentrations were evaluated, and biomass fuel users exhibited high cancer risks and low embryo survival chances due to particulate PAH exposure. The average total cost of reducing the incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) to acceptable levels was lower when shifting from biomass to LPG stoves than when shifting to electric stoves. Graphical abstract

Regulatory Science Perspective on the Analysis of Microplastics and Nanoplastics in Human Food.

Microplastics are increasingly reported, not only in the environment but also in a wide range of food commodities. While studies on microplastics in food abound, the current state of science is limited in its application to regulatory risk assessment by a continued lack of standardized definitions, reference materials, sample collection and preparation procedures, fit-for purpose analytical methods for real-world and environmentally relevant plastic mixtures, and appropriate quality controls. This is particularly the case for nanoplastics. These methodological challenges hinder robust, quantitative exposure assessments of microplastic and nanoplastic mixtures from food consumption. Furthermore, limited toxicological studies on whether microplastics and nanoplastics adversely impact human health are also impeded by methodology challenges. Food safety regulatory agencies must consider both the exposure and the risk of contaminants of emerging concern to ascertain potential harm. Foundational to this effort is access to and application of analytical methods with the capability to quantify and characterize micro- and nanoscale sized polymers in complex food matrices. However, the early stages of method development and application of early stage methods to study the distribution and potential health effects of microplastics and nanoplastics in food have largely been done without consideration of the stringent requirements of methods to inform regulatory activities. We provide regulatory science perspectives on the state of knowledge regarding the occurrence of microplastics and nanoplastics in food and present our general approach for developing, validating, and implementing analytical methods for regulatory purposes.

Airway Diseases Related to the Use of Cleaning Agents in Occupational Settings

Exposure to disinfectants and cleaning products (DCP) is now a well-established risk factor for work-related asthma (WRA). However, questions remain on the specific causal agents and pathophysiological mechanisms. Few studies have also reported an association between DCP and rhinitis or chronic obstructive pulmonary disease. This review discusses the recent evidence pertaining to airway diseases attributable to occupational exposure to DCP. In contrast to other agents, the incidence of WRA due to DCP has increased over time. The use of DCP in spray form has clearly been identified as an added risk factor. The mechanisms for WRA associated with DCP remain poorly studied, however, both allergic and nonallergic responses have been described, with irritant mechanisms thought to play a major role. An early diagnostic work-up based on clinical assessment accompanied by evaluation of lung function, immunological and airway inflammatory markers is important to guide optimal care and exposure avoidance to the implicated agent. Future research should focus on the effects of “green” products, pathophysiological mechanisms and quantitative exposure assessment including the use of barcode-based methods to identify specific agents. There is an urgent need to strengthen preventive measures and interventions to reduce the burden of airway diseases associated with DCP.

A Study on Assessment of Noise Exposure in the Port Industry: Implications for Occupational Health and Safety

The workplace today is getting more complex, as exposure to chemical, physical, and biological substances at work poses an increasing range of hazards and risks. Industrial hygiene is "that science and art devoted to the anticipation, recognition, evaluation, and control of those environmental factors or stresses arising in or from the workplace". Exposure assessment is the heart of industrial hygiene initiatives, which serves as the foundation for all other functional elements, including medical surveillance, exposure monitoring, engineering controls, administrative controls, and hazardous materials management. Ports are key hubs for worldwide trade, handling a wide range of cargo types with various machinery and equipment. The operational activities within these environments frequently generate high levels of noise, posing a potential hazard to the well-being of the workforce. The purpose of this study is to conduct a comprehensive assessment of noise exposure in the port industry at different locations and to propose appropriate mitigation strategies. The methodology involves the use of sound level measurements using a sound level meter in various port environments. A thorough examination was carried out to identify specific locations for the purpose of conducting noise monitoring. The survey facilitated the quantitative assessment of noise exposure. Based on the findings of this study, necessary recommendations are proposed to minimize noise exposure and protect the well-being of port workers. The insights gained will not just assist port workers but will also contribute to a broader awareness of sustainable and responsible industrial practices. Keywords: Noise exposure, Port industry, Noise assessment, Noise control methods, Personal protective equipment.

Micro-environmental factors impact breathing zone exposures: A simulated petrochemical manufacturing facility task

This study investigates the impact of micro-environmental factors on worker breathing zone exposure levels in petrochemical facilities. A laboratory simulation study evaluated near-field exposure to methane for a typical maintenance task. Individual and combinations of micro-environmental factors significantly affected methane exposure. Airflow direction and speed were significant determinants of exposure concentration reduction. A side airflow direction at medium to high speed produced the lowest gas concentration in the breathing zone. Worker body orientation relative to the methane emission point was also a critical factor affecting gas concentration in the worker's breathing zone. The study provides insights into how variations in airflow and small changes in position impact near-field exposures for petrochemical tasks, guiding industrial hygiene professionals' training on qualitative exposure estimation and providing input for near-field exposure modeling to guide quantitative exposure and risk assessment.

Quantitative thermodynamic exposure assessment of PCBs available to sandworms (Alitta virens) in activated carbon remediated sediment during ongoing sediment deposition.

Marine mesoscale studies with sandworms (Alitta virens) were conducted to isolate important processes governing the exposure and bioaccumulation of polychlorinated biphenyls (PCBs) at contaminated sediment sites. Ex situ equilibrium sampling with silicone-coated jars, and in situ passive sampling with low-density polyethylene (LDPE) were used to determine the performance of an activated carbon (AC) amendment remedy applied to the bed sediment. A quantitative thermodynamic exposure assessment ('QTEA') was performed, showing that PCB concentrations in polymers at equilibrium with the surficial sediment were suited to measure and assess the remedy effectiveness with regard to PCB bioaccumulation in worms. In practice, monitoring the performance of sediment remedies should utilize a consistent and predictive form of polymeric sampling of the sediment. The present study found that ex situ equilibrium sampling of the surficial sediment was the most useful for understanding changes in bioaccumulation potential as a result of the applied remedy, during bioturbation and ongoing sediment and contaminant influx processes. The ultrathin silicone coatings of the ex situ sampling provided fast equilibration of PCBs between the sediment interstitial water and the polymer, and the multiple coating thicknesses were applied to confirm equilibrium and the absence of surface sorption artifacts. Overall, ex situ equilibrium sampling of surficial sediment could fit into existing frameworks as a robust and cost-effective tool for contaminated sediment site assessment.

Assessment of nonylphenol exposure based on global urinary concentration data and its risk analysis

Nonylphenol (NP) has been recognized as a priority hazardous substance because of its estrogenic activity and ubiquity in the environment. Therefore, it is important to understand the daily intake of NP in humans and evaluate the potential health risks of NP. The median or average estimated daily intake (EDI) of NP was estimated based on urinary NP or alkyl-chain-oxidized NP metabolites concentration data from published epidemiological studies. In brief, we acquired 34 peer-reviewed publications, which contained 14235 samples from twelve countries or regions. The global average estimated daily intake of NP was 1.003 μg/(kg bw·day), which was lower than the tolerable daily intake recommended by the Danish Veterinary and Food Authority [5 μg/(kg bw·day)]. Korea had the highest exposure level [3.471 μg/(kg bw·day)] among different countries or regions. Compared with the adult [0.743 μg/(kg bw·day)] and pregnant women [0.806 μg/(kg bw·day)] groups, the children group had the highest estimated daily intake of NP at 2.368 μg/(kg bw·day). Besides, the global NP risk hazard quotient was 0.201, and the risk hazard quotients of all countries or regions were less than 1. However, the global HQ value of the 95th quantile population was 2.299, which was much higher than 1, the potential health risk cannot be ignored and needs to be confirmed by more research. To our knowledge, this is the first study to assess the overall NP exposure levels based on published biomonitoring data, and has important implications for assessing the potential effects of NP exposure on human health. In addition, OH-NP is a robust and sensitive novel biomarker for NP, there are fewer studies on the application of this biomarker, and more studies are needed in the future for quantitative exposure and risk assessment of NP.

Quantitative assessment of multiple pathogen exposure and immune dynamics at scale.

Serology reveals exposure to pathogens, as well as the state of autoimmune and other clinical conditions. It is used to evaluate individuals and their histories and as a public health tool to track epidemics. Employing a variety of formats, studies nearly always perform serology by testing response to only one or a few antigens. However, clinical outcomes of new infections also depend on which previous infections may have occurred. We developed a high-throughput serology method that evaluates responses to hundreds of antigens simultaneously. It can be used to evaluate thousands of samples at a time and provide a quantitative readout. This tool will enable doctors to monitor which pathogens an individual has been exposed to and how that changes in the future. Moreover, public health officials could track populations and look for infectious trends among large populations. Testing many potential antigens at a time may also aid in vaccine development.

The relevance of oral exposure in the workplace: a systematic review and meta-analysis.

The inclusion of all relevant exposure routes in the exposure assessment is essential for the protection of workers. However, under European chemical regulations but also for workplace risk assessments according to occupational safety and health (OSH) requirements, the quantitative assessment of oral exposure is usually neglected assuming good occupational hygiene. In contrast, several studies point to the importance of unintentional ingestion in the workplace. To our knowledge, there is no systematic analysis of the extent of this exposure route. Therefore, the aim of this study was to assess systematically the current knowledge on the relevance of occupational oral exposure using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. Five electronic databases and nine institutional websites were searched for all publications on the relevance. The data were extracted into a concept matrix. In the subsequent meta-analysis, the identified conclusions on the relevance were analyzed. In addition, the measurement methods or modeling approaches that were described for occupational oral exposure were determined as well as the potentially relevant workplaces and substances. In total, 147 studies were included in this analysis that contain a general or several, differentiated assessments of the relevance of occupational oral exposure. Nine of these studies assessed this exposure route as irrelevant. However, 123 studies considered oral exposure as potentially contributing and 80 studies explicitly identified it as relevant. 78 and 94 of the publications described modeling and measurement approaches, respectively. The workplaces frequently identified as potentially or explicitly relevant were other indoor, other industrial or recycling workplaces. Analogously, metals, dust and powders or pesticides were the most frequently investigated substance groups. As several studies assessed occupational oral exposure as relevant in the context of different workplaces and substances, further investigation of this exposure route is needed. This systematic review and meta-analysis serve as a basis for further development of feasible assessment methods for this route of exposure.

Deposition of secondary organic aerosol in human lung model: Effect of photochemically aged aerosol on human respiratory system

Ultrafine particles (UFP) of Secondary Organic Aerosol (SOA) penetrate deep into the human respiratory system and exert fatal effects on human health. However, there is little data on the potential deposited doses of UFP-generated SOA in the human respiratory tract. This study is to estimate the fraction of aerosol deposition using a multiple-path-particle-dosimetry (MPPD) model. For relevancy of real life, the model employed measured concentrations of toluene-derived fresh and aged SOA produced within serially connected smog chamber and PAM-OFR (Potential Aerosol Mass-Oxidation Flow Reactor) under atmospheric environmental conditions (NOx and relative humidity). The number concentrations and chemical composition of fresh and aged aerosols produced within the chambers were measured using Scanning Mobility Particle Sizer (SMPS) and High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), while the morphology of individual particles was analyzed using Scanning Electron Microscopy (SEM). The number concentration of aged SOA-w/s was more than double compared to that of fresh SOA-w/s (maximum reached after 10 h) with its size less than 100 nm. The O:C ratio for aged SOA-w/s were 0.96 and 1.15 depending on RH (0.96 at 3% RH and 1.15 at 50% RH), and individual spherical particles containing water were present in agglomerates with its size of less than 1 µm. In all inhalable fresh and aged SOA produced in the two chambers, 5–22% of aerosol is deposited in the Head airways, 4–8% in the tracheobronchial, and 8–34% in the alveolar regions. The predominant deposition of the aged aerosol occurred in the alveoli (in the generation 20th lobe), and the deposition faction in the alveoli was 2–3 times higher in the children group than the adults group. This study presented a quantitative exposure assessment of SOA generated under a realistic simulation and suggested the possibility of evaluating long-term exposure to SOA and potential health effects by determining the potential inhalable aerosol doses and the fraction of deposition in the human respiratory system.

Risk mitigation measures for pesticide runoff: How effective are they?

One of the most important sources of pesticide pollution of surface waters is runoff and erosion from agricultural fields after rainfall. This study analyses the efficacy of different risk mitigation measures to reduce pesticide runoff and erosion inputs into surface waters from arable land excluding rice fields. Three groups of risk mitigation measures were quantitatively analyzed: vegetative filter strips, micro-dams in row crops and soil conservation measures. Their effectiveness was evaluated based on a meta-analysis of available experimental data using statistical methods such as classification and regression trees, and exploratory data analysis. Results confirmed the effectiveness of vegetative filter strips and micro-dams. Contrary to common assumption, the width of vegetative filter strips alone is not sufficient to predict their effectiveness. The effectiveness of soil conservation measures (especially mulch-tillage) varied widely. This was in part due to the heterogeneity of the available experimental data, probably resulting from the inconsistent implementation and the inadequate definitions of these measures. Both vegetative filter strips and micro-dams are effective and suitable, and can therefore be recommended for quantitative assessment of environmental pesticide exposure in surface waters. However, the processes of infiltration and sedimentation in vegetative filter strips should be simulated with a mechanistic model like Vegetative Filter Strip Modeling System, VFSMOD. The reduction effect of micro-dams can be modelled by reducing the runoff curve number, e.g., in the pesticide root zone model, PRZM. Soil conservation measures are in principle promising, but further well-documented data are needed to determine under which conditions they are effective. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Laboratory comparison of field portable X-ray fluorescence spectrometer (FP-XRF) and inductively coupled plasma mass spectrometry (ICP-MS) for determination of airborne metals in stainless steel welding fume

Welding fume is a common exposure in occupational settings. Gravimetric analysis for total particulate matter is common; however, the cost of laboratory analyses limits the availability of quantitative exposure assessment for welding fume metal constituents in occupational settings. We investigated whether a field portable X-ray fluorescence spectrometer (FP-XRF) could provide accurate estimates of personal exposures to metals common in welding fume (chromium, copper, manganese, nickel, vanadium, and zinc). The FP-XRF requires less training and is easier to deploy in many settings than traditional wet laboratory analyses. Filters were analyzed both by FP-XRF and inductively coupled plasma mass spectrometry (ICP-MS). We estimated the FP-XRF limit of detection for each metal and developed a correction factor accounting for the non-uniform deposition pattern on filter samples collected with an Institute of Medicine (IOM) inhalable particulate matter sampler. Strong linear correlation was observed for all metals (0.72<r < 0.96). The median percent bias for chromium and nickel was less than 15%. The linear slope between the two methods for some metals (copper, manganese, and zinc) was greater than 1, indicating that the FP-XRF overestimated metal mass (median percent bias for vanadium was the largest at 94%), but the linearity of the response suggests that appropriate correction factors could be developed.

Incorporating Bioaccessibility into Inhalation Exposure Assessment of Emamectin Benzoate from Field Spraying.

The inhalation exposure of pesticide applicators and residents who live close to pesticide-treated fields is a worldwide concern in public health. Quantitative assessment of exposure to pesticide inhalation health risk highlights the need to accurately assess the bioaccessibility rather than the total content in ambient air. Herein, we developed an in vitro method to estimate the inhalation bioaccessibility of emamectin benzoate and validated its applicability using a rat plasma pharmacokinetic bioassay. Emamectin benzoate was extracted using the Gamble solution, with an optimized solid-to-liquid ratio (1/250), extraction time (24 h), and agitation (200 rpm), which obtained in vitro inhalation bioaccessibility consistent with its inhalation bioavailability in vivo (32.33%). The margin of exposure (MOE) was used to assess inhalation exposure risk. The inhalation unit exposures to emamectin benzoate of applicators and residents were 11.05-28.04 and 0.02-0.04 ng/m3, respectively, varying markedly according to the methods of application, e.g., formulations and nozzles. The inhalation risk assessment using present application methods appeared to be acceptable; however, the MOE of emamectin benzoate might be overestimated by 32% without considering inhalation bioaccessibility. Collectively, our findings contribute insights into the assessment of pesticide inhalation exposure based on bioaccessibility and provide guidance for the safe application of pesticides.

78 Nano Exposure Quantifier (NEQ) - A Quantitative tool for Assessing Exposure in the Workplace

Abstract Background The EU Horizon2020 “safe-by-design for Nano” (SBD4Nano) project aims to develop a tool to assist users in the safe-by-design process and decisions to reduce risk as a result from working with- or using newly developed products containing manufactured nanomaterials (MNs). Therefore, TNO set out to develop an easy-to-use quantitative exposure assessment tool that helps users with different levels of expertise to reduce the exposure from MNs following an integrated Tiered safe-by-design approach. Method Based on previous projects, literature, expert knowledge, a Tiered set of model determinants and corresponding calculations were integrated into a conceptual model. Also, an exposure database based on the EU GRACIOUS template was created containing a large set of exposure measurements collected from diverse literature studies. Machine learning was applied to these exposure measurements to validate and refine the model. Lastly, a safe-by-design module was added to assist users modify their material or process design to reduce exposure. Results An online tool is realized that will be freely available on https://diamonds.tno.nl/#neq. The NEQ offers a Tiered approach by smartly adapting the questions based on the depth of information the user can provide allowing anywhere between a Tier-1 and a Tier-2 approach. After answering questions, the user is presented an exposure estimate including uncertainty of the current design. The user is guided to enter a new design that reduces the exposure and/or its uncertainty.

Effect of 450 nm Visible Blue Light from Light-Emitting Diode on Escherichia coli O157:H7 in Agar Gels: Optimizing the Lighting Array and Quantitative Microbial Exposure Assessment

Visible blue light emitting diodes (LED) have been studied to inactivate Escherichia coli (E. coli) O157:H7 in agar gels. The LED array was optimized to attain uniform light illumination, and the light intensity distribution was visualized through optical simulation. The uniformity of LED light intensity was assessed, and the evenly spaced array showed the best uniformity with a Petri factor of 0.99. Microbial populations in agar gels prepared with and without a dye were analyzed after light irradiation. Each segment of the gels with different heights was taken to measure microbial reduction, and the results indicated that optical properties, such as opaqueness, played an important role in microbial reduction. The agar gel without and with a dye showed a maximum reduction of &lt;3.4 and &lt;2.1 log CFU/g, respectively. An exposure assessment for E. coli O157:H7 was conducted based on the assumption for the agar gel product after LED illumination. The probability results indicated that a risk (&gt;5 log CFU/g) existed mainly in the bottom layer of the sample, despite the average contamination being &lt;5 log CFU/g. This study provides a suitable approach for designing the LED photoinactivation process and subsequent exposure assessment to avoid risk.

Quantitative risk assessment of occupational exposure to PCDD/Fs in the waste incineration industry

Objective: To analyze the level of PCDD/Fs exposure of occupational workers in the waste incineration industry and explore the risk of occupational exposure. Methods: In September 2021, literature on environmental PCDD/Fs exposure in waste incineration plants published from the establishment of the database to February 10, 2021 was retrieved from CNKI database. A total of 1365 literatures were retrieved, and 7 met the criteria for inclusion. The US Environmental Protection Agency (EPA) inhalation risk model was used to assess and analyze carcinogenic and non-carcinogenic risks of PCDD/Fs exposure among occupational workers in the waste incineration industry. Results: A total of 86 sampling sites were included in incineration plants in 7 regions. The study of Wuhan area showed that the concentration of working environment near the waste incinerator in the same factory was the highest, followed by the rest and office area in the factory. The concentration of PCDD/Fs in waste incinerators was the highest in Southwest China (4880.00-24880.00 pg TEQ/m(3)), and the lowest in Shenzhen (0.02-0.44 pg TEQ/m(3)). According to the cancer risk assessment, with the increase of exposure years, the risk of cancer increased. The highest risk of cancer was found in the waste incineration plants in Southwest China. When the exposure period was 1 year, the risk was moderate (22.40×10(-6)-114.20×10(-6)). When the exposure time was more than 5 years, the risk of cancer was high. In Jinan, workers working near the incinerator had a moderate risk of cancer after five years of exposure. In Zhejiang, workers were at medium risk of cancer after exposure for more than 20 years. Workers in Wuhan, Shanghai, Zhejiang Province, Shenzhen and the Pearl River Delta were still at low risk of cancer after 40 years of occupational exposure. HQ>1 of workers working near the waste incinerators in Jinan, Zhejiang Province and Southwest China, and the qualitative evaluation results showed that the non-carcinogenic risk was unacceptable. Conclusion: There are great differences in PCDD/Fs of occupational exposure in waste incineration industry, and the occupational exposure exceeding the occupational exposure limit has higher carcinogenic and non carcinogenic risks.

Quantitative assessment of aflatoxin exposure and hepatocellular carcinoma (HCC) risk associated with consumption of select Nigerian staple foods

Aflatoxin contamination of staple grains and legumes has been linked to hepatocellular carcinoma (HCC) and other adverse health outcomes, constituting a substantial public health concern globally. Low-resource food environments in sub-Saharan Africa are often under-regulated and are particularly vulnerable to adverse health and nutrition outcomes associated with aflatoxin exposure. This study identifies levels of HCC risk in the northern Nigerian adult population, leveraging a systematic review of available evidence on aflatoxin contamination in Nigerian maize, groundnut, rice, cowpea, and soybean. Estimated dietary intake (EDI) was computed using publicly available dietary consumption data and a probabilistic quantitative risk assessment was conducted to determine the relative risk of HCC associated with consumption of selected aflatoxin-contaminated commodities. In total, 41 eligible studies reporting aflatoxin contamination were used to model the distribution of aflatoxin concentrations in Nigerian commodities. EDIs for maize, groundnut, rice, and cowpea exceeded the provisional maximum tolerable daily intake (PMTDI) level of 1 kgbw-1 day-1, with maize yielding the highest mean EDI (36.7 kgbw-1 day-1). The quantitative risk assessment estimated that 1.77, 0.44, 0.43, 0.15, and 0.01 HCC cases per year/100,000 population were attributable to aflatoxin exposure through maize, groundnut, rice, cowpea, and soybean, respectively. Sensitivity analysis revealed that aflatoxin concentration, dietary consumption levels, consumption frequency, and other variables have differing relative contributions to HCC risk across commodities. These findings constitute a novel multi-study risk assessment approach in the Nigerian context and substantiate existing evidence suggesting that there is reason for public health concern regarding aflatoxin exposure in the Nigerian population.

Wearable Passive Samplers for Assessing Environmental Exposure to Organic Chemicals: Current Approaches and Future Directions.

We are continuously exposed to dynamic mixtures of airborne contaminants that vary by location. Understanding the compositional diversity of these complex mixtures and the levels to which we are each exposed requires comprehensive exposure assessment. This comprehensive analysis is often lacking in population-based studies due to logistic and analytical challenges associated with traditional measurement approaches involving active air sampling and chemical-by-chemical analysis. The objective of this review is to provide an overview of wearable passive samplers as alternative tools to active samplers in environmental health research. The review highlights the advances and challenges in using wearable passive samplers for assessing personal exposure to organic chemicals and further presents a framework to enable quantitative measurements of exposure and expanded use of this monitoring approach to the population scale. Overall, wearable passive samplers are promising tools for assessing personal exposure to environmental contaminants, evident by the increased adoption and use of silicone-based devices in recent years. When combined with high throughput chemical analysis, these exposure assessment tools present opportunities for advancing our ability to assess personal exposures to complex mixtures. Most designs of wearable passive samplers used for assessing exposure to semi-volatile organic chemicals are currently uncalibrated, thus, are mostly used for qualitative research. The challenge with using wearable samplers for quantitative exposure assessment mostly lies with the inherent complexity in calibrating these wearable devices. Questions remain regarding how they perform under various conditions and the uncertainty of exposure estimates. As popularity of these samplers grows, it is critical to understand the uptake kinetics of chemicals and the different environmental and meteorological conditions that can introduce variability. Wearable passive samplers enable evaluation of exposure to hundreds of chemicals. The review presents the state-of-the-art of technology for assessing personal exposure to environmental chemicals. As more studies calibrate wearable samplers, these tools present promise for quantitatively assessing exposure at both the individual and population levels.