Exposure Assessment Purposes Research Articles

Geographic and record-based pesticide exposure assessment, biologic exposure signatures, and chronic disease modelling in California

Background and Aims: For the past 50 years, California has been recording agricultural pesticide applications in a pesticide use reports (PUR) database; i.e. documenting use for several hundred pesticide active ingredients. These data can be employed in exposure assessment purposes targeting specific pesticides and pesticide mixtures and study a range of adverse health outcomes. Methods: In collaboration with M. Cockburn at USC, my team at UCLA has generated a geographic information system tool that uses these records in conjunction with land use data to generate spatio-temporal exposure measures for the California population living near agricultural applications. Over the past 2 decades we have used this tool kit to estimate pesticide related health effects including studies of adverse birth outcomes, autism, cerebral palsy, childhood brain cancers, Parkinson’s and Alzheimer’s disease. Results: I will present and discuss common as well as special challenges for exposure assessment and the results of the studies we conducted in the past 2 decades. Furthermore, we investigated whether long- or shorter-term exposures to agricultural use pesticides assessed with the PUR tools generate exposure signals in biological systems and bio-fluids, i.e. relying on human blood samples from older adult residents of central California to examine metabolomic patterns, methylation changes, and influences that certain pesticides have on the gut microbiome. Using integrative omics analyses, we also examined overlap between pesticide-associated biologic pathways and pathways known to be perturbed in certain diseases. Conclusions: These studies help to systematically identify physiologic responses to chronic pesticide exposures. Eventually this will help to better understand how low-level chronic pesticide exposures may contribute to chronic brain diseases in real world exposure scenarios. Keywords: pesticides, exposure assessment, Parkinson’s disease, neurodevelopment, multi-omics

Cadmium exposure in adults across Europe: Results from the HBM4EU Aligned Studies survey 2014-2020.

The objectives of the study were to estimate the current exposure to cadmium (Cd) in Europe, potential differences between the countries and geographic regions, determinants of exposure and to derive European exposure levels. The basis for this work was provided by the European Human Biomonitoring Initiative (HBM4EU) which established a framework for alignment of national or regional HBM studies. For the purpose of Cd exposure assessment, studies from 9 European countries (Iceland, Denmark, Poland, Czech Republic, Croatia, Portugal, Germany, France, Luxembourg) were included and urine of 20-39 years old adults sampled in the years 2014-2021 (n=2510). The measurements in urine were quality assured by the HBM4EU quality assurance/quality control scheme, study participants' questionnaire data were post-harmonized. Spatially resolved external data, namely Cd concentrations in soil, agricultural areas, phosphate fertilizer application, traffic density and point source Cd release were collected for the respective statistical territorial unit (NUTS). There were no distinct geographic patterns observed in Cd levels in urine, although the data revealed some differences between the specific study sites. The levels of exposure were otherwise similar between two time periods within the last decade (DEMOCOPHES - 2011-2012 vs. HBM4EU Aligned Studies, 2014-2020). The age-dependent alert values for Cd in urine were exceeded by 16% of the study participants. Exceedances in the different studies and locations ranged from 1.4% up to 42%. The studies with largest extent of exceedance were from France and Poland. Association analysis with individual food consumption data available from participants' questionnaires showed an important contribution of vegetarian diet to the overall exposure, with 35% higher levels in vegetarians as opposed to non-vegetarians. For comparison, increase in Cd levels due to smoking was 25%. Using NUTS2-level external data, positive associations between HBM data and percentage of cropland and consumption of Cd-containing mineral phosphate fertilizer were revealed, which indicates a significant contribution of mineral phosphate fertilizers to human Cd exposure through diet. In addition to diet, traffic and point source release were identified as significant sources of exposure in the study population. The findings of the study support the recommendation by EFSA to reduce Cd exposure as also the estimated mean dietary exposure of adults in the EU is close or slightly exceeding the tolerable weekly intake. It also indicates that regulations are not protecting the population sufficiently.

Ocena narażenia zawodowego na frakcję respirabilną krzemionki krystalicznej powstającą w trakcie pracy

Among the forms of crystalline silica (silicon dioxide minerals) that are most common in the natural and work environments are quartz and cristobalite. They are used in various industries, including in the ceramics, glass and construction industries and pose a serious health risk to workers. The respirable of crystalline silica (RCS), which penetrates into the gas exchange area of the lungs causes chronic inflammatory reactions, followed by fibrotic changes in the lung tissue and, as a result, silicosis pneumoconiosis, often leading to lung cancer. Both employers and health and safety managers have great difficulties with the interpretation and application of legal provisions concerning the measurement of RCS concentrations (for the purpose of occupational exposure assessment) and the classification of work involving exposure to respirable dust generated during technological processes. The information in this article should help you resolve these issues.

A spatiotemporal ensemble model to predict gross beta particulate radioactivity across the contiguous United States.

Particulate radioactivity, a characteristic of particulate matter, is primarily determined by the abundance of radionuclides that are bound to airborne particulates. Exposure to high levels of particulate radioactivity has been associated with negative health outcomes. However, there are currently no spatially and temporally resolved particulate radioactivity data for exposure assessment purposes. We estimated the monthly distributions of gross beta particulate radioactivity across the contiguous United States from 2001 to 2017 with a spatial resolution of 32km, via a multi-stage ensemble-based model. Particulate radioactivity was measured at 129 RadNet monitors across the contiguous U.S. In stage one, we built 264 base learning models using six methods, then selected nine base models that provide different predictions. In stage two, we used a non-negative geographically and temporally weighted regression method to aggregate the selected base learner predictions based on their local performance. The results of block cross-validation analysis suggested that the non-negative geographically and temporally weighted regression ensemble learning model outperformed all base learning model with the smallest rooted mean square error (0.094mBq/m3). Our model provided an accurate estimation of particulate radioactivity, thus can be used in future health studies.

A Paper Based Milli-Cantilever Sensor for Detecting Hydrocarbon Gases via Smartphone Camera.

Hydrocarbon gases, especially toxic ones like benzene and xylene, pose threats to human health and the environment. But existing detection techniques, like bulky GC-MS or portable PID, cannot fulfill people's requirement of affordable and reliable hydrocarbons monitoring for the purpose of personal exposure assessment. Here, a simple, low cost, and light hydrocarbon gases sensor using a smartphone camera as a readout was developed based on the paper based milli-cantilever bending induced by polymer swelling. Its sensing cantilever was composed of three layers: functional layer of polyethylene film, adhesive layer of double-side tape, and a substrate of weighing paper. And the dimensions of the milli-fabricated sensing cantilever are 8 mm long, 0.5 mm wide, and 50 μm thick. The sensor response was the displacement of milli-cantilever free end. As proof of concept, its performance to typical hydrocarbons of xylene, hexane, and BTEX was carefully examined. For all of them, the sensor showed good performance of linear response to hydrocarbon concentrations, wide detection range, low detection, and fast response. Taking xylene for example, the sensor showed wide detection range of 15-140 ppm, low detection limit of 15 ppm, and fast response of 30 s. The sensor cross-sensitivity to other hydrocarbons was consistent with polymer swelling theory that the more carbons the hydrocarbon has, the higher the sensor sensitivity. Taking advantage of the rough materials chosen and simple fabrication procedure, the developed sensors also had high stability with time, low cost, and good uniformity. The developed sensor is affordable both physically and financially, has good performance, could meet hydrocarbons monitoring requirements for occupational safety or air pollution in petroleum industry, and would benefit people's health.

Representativeness of an air quality monitoring station for PM2.5 and source apportionment over a small urban domain

In this study, PM2.5 concentrations together with the water-soluble ionic compounds and total elements were simultaneously measured at 16 sites in the city of Varese located in Northern Italy within a domain of 2 × 2 km2. The center point of this domain consisted of an existing urban air quality monitoring station. The representativeness of the monitoring station for PM2.5 mass and chemical composition was estimated using a methodology relying on statistical/geostatistical analyses. Source apportionment by means of the Chemical Mass Balance (CMB) receptor model was also performed to evaluate the spatial distribution of source contribution throughout the domain. Very high soluble fraction was found for Cd, Sb, K and V, indicating the anthropogenic origin of those elements. The geostatistical analysis/mapping showed that the monitoring station captured the spatial variation of PM2.5 and most of the anthropogenic originated elements, e.g., As, Cd and V, whereas it did not captured the spatial patterns of the ones originated from both natural and anthropogenic sources, e.g., Na, Ni, Pb, K, Zn, Fe, Cr, and Ti. The CMB source contribution estimations in the monitoring station were at least 25% different from many sites of the domain for PM2.5. The significant spatial variation in concentrations and source contribution estimates showed that the monitoring station could not be considered representative for the air quality monitoring studies with exposure assessment and source apportionment purposes in Varese.

Determination of Deoxynivalenol Biomarkers in Italian Urine Samples.

Deoxynivalenol (DON) is a mycotoxin mainly produced by Fusarium graminearum that can contaminate cereals and cereal-based foodstuff. Urinary DON levels can be used as biomarker for exposure assessment purposes. This study assessed urinary DON concentrations in Italian volunteers recruited by age group, namely children, adolescents, adults, and the elderly. In addition, vulnerable groups, namely vegetarians and pregnant women, were included in the study. To determine the urinary DON, its glucuronide and de-epoxydated (DOM-1) forms, an indirect analytical approach was used, measuring free DON and total DON (as sum of free and glucuronides forms), before and after enzymatic treatment, respectively. Morning urine samples were collected on two consecutive days, from six different population groups, namely children, adolescent, adults, elderly, vegetarians and pregnant women. Total DON was measured in the 76% of the collected samples with the maximum incidences in children and adolescent age group. Urine samples from children and adolescent also showed the highest total DON levels, up to 17.0 ng/mgcreat. Pregnant women had the lowest positive samples per category (40% for day 1 and 43% for day 2, respectively), low mean levels of total DON (down to 2.84 ng/mgcreat) and median equal to 0 ng/mgcreat. Estimation of DON dietary intake reveals that 7.5% of the total population exceeds the TDI of 1 μg/kg bw/day set for DON, with children showing 40% of individuals surpassing this value (male, day 2).

Interview

Valentina Hartwig Doctor Valentina Hartwig from the National Research Council in Italy, talks to Electronics Letters about the paper ‘New device for the assessment of occupational exposure to time-varying magnetic field due to movement in Magnetic Resonance environments’, page 579. I have been intrigued by the interactions between electromagnetic fields and biological tissues for many years, and my PhD was on this topic. This is an interesting research topic and what I love most about this subject is its multidisciplinary approach. Specifically, exposure to electromagnetic fields in Magnetic Resonance (MR) environments is currently a hot topic. MR is widely used for clinical applications and, at the Institute of Clinical Physiology where I work, is also used as a powerful research tool for cardiovascular diseases. In the past, we studied patient exposure to electromagnetic fields in MR and, at present, we focus on occupational exposure in MR environments, an exciting challenge. According to the most recent international regulations and guidelines, training of MR professionals is necessary to avoid the risks of high electromagnetic field exposure. There is still the lack of a practical method for exposure assessment, particularly when considering risks for MR staff moving across the permanent static magnetic field straying from the scanner. For these reasons, we had the idea to design a device for assessing personal exposure to the magnetic fields, to use not only as a “personal dosimeter”, but also for educational purposes. Our target was using this simple instrument to identify preventive measures and to provide staff with some recommendations on how to move around the MR room during daily clinical practice. There are at present some commercial MR dosimeters, but these devices have been designed for exposure assessment purposes at only one position on the workers body and are not suitable for newer research MR scanners with very high values of static magnetic fields. Our device is designed for research purposes, offering the possibility to measure the magnetic field at different positions on the body simultaneously, which is important in epidemiological studies. Moreover, it may be used in all clinical MR environments and in experimental MR scanners with a static magnetic field value up to 7 T. In its development is encompassed our mission of “technology transfer”, from basic research to industry and, it is the result of successful cooperation between research institutions and industrial partners. An MR site is an environment which poses exciting challenges, especially for designing an electronic device for use within it, as even the simplest electronic circuit may not function correctly. Our challenge was to design a wearable device that is not affected by the fields present and permits measurement and recording of exposure parameters; all without disturbing the work of the operator wearing it. This was possible thanks to the thorough study of the chosen material and components electromagnetic compatibilities. We performed many tests both in the laboratory and in real MR environments and achieved our goal thanks to the hard work of a multidisciplinary team. In the short term, we expect that the device described in our paper will be useful in better understanding occupational exposure to magnetic fields in MR sites. In the longer term, after optimisation of the present prototype, the device may be commercialised and used for workers training and/or epidemiological studies. Future developments of this work will regard the optimisation of the device in terms of size, storage capacity, and the implementation of a wireless-real-time connection to a host device. We are also working on a computational tool for the estimation of occupational exposure to time-varying electromagnetic fields due to the movement inside the MR environment. In recent years, the scientific community's interest in MR environment safety has been growing exponentially, especially after the publication, in 2013, of a specific Directive of the EU, followed in 2014 by updated ICNIRP guidelines. To date, there are many scientific works which deal with MR safety, hence we have a good understanding of magnetic field exposure levels by workers. What is still missing today are epidemiological studies conducted using consolidated assessment methodologies to collect exposure data at a personal level by means of simple everyday equipment. I think that over the next ten years research on this topic will grow both from the point of view of studies on the biological effects of electromagnetic fields typical of the MR environment, and from that of devices for measuring exposure to this type of physical agents. Our work will, therefore, contribute to this latter research activity.

Bioaerosols Play a Major Role in the Nasopharyngeal Microbiota Content in Agricultural Environment.

Background: Bioaerosols are a major concern for public health and sampling for exposure assessment purposes is challenging. The nasopharyngeal region could be a potent carrier of long-term bioaerosol exposure agents. This study aimed to evaluate the correlation between nasopharyngeal bacterial flora of swine workers and the swine barns bioaerosol biodiversity. Methods: Air samples from eight swine barns as well as nasopharyngeal swabs from pig workers (n = 25) and from a non-exposed control group (n = 29) were sequenced using 16S rRNA gene high-throughput sequencing. Wastewater treatment plants were used as the industrial, low-dust, non-agricultural environment control to validate the microbial link between the bioaerosol content (air) and the nasopharynxes of workers. Results: A multivariate analysis showed air samples and nasopharyngeal flora of pig workers cluster together, compared to the non-exposed control group. The significance was confirmed with the PERMANOVA statistical test (p-value of 0.0001). Unlike the farm environment, nasopharynx samples from wastewater workers did not cluster with air samples from wastewater treatment plants. The difference in the microbial community of nasopharynx of swine workers and a control group suggest that swine workers are carriers of germs found in bioaerosols. Conclusion: Nasopharynx sampling and microbiota could be used as a proxy of air sampling for exposure assessment studies or for the determination of exposure markers in highly contaminated agricultural environments.

Qualitative and quantitative composition of essential oils: A literature-based database on contact allergens used for safety assessment

The risks related to the use of essential oils are difficult to ascertain at present, due in part to the large number of different oils available on the market, making it difficult for the risk assessor. Essential oils may contain skin allergens in significant amounts, and could thus pose a risk to the consumer. The aim of our study was to collect as much qualitative and quantitative data as possible on allergens present in essential oils. 11 types of essential oils, with 25 respective subspecies, were taken into account based on a previous survey. Based on the literature, 517 dosages were recorded from 112 publications, providing precious information for probabilistic exposure assessment purposes. 22 substances recognized as established allergens were found in the essential oils we included. Of these, 11 are also found in cosmetics as fragrance components. These results are of major importance regarding co-exposure to fragrance allergens. Moreover, this could lead to regulatory measures for essential oils in the future, as it is the case for cosmetic products, in order to better protect consumers against skin allergy.

Bridging across OECD 308 and 309 Data in Search of a Robust Biotransformation Indicator.

The OECD guidelines 308 and 309 define simulation tests aimed at assessing biotransformation of chemicals in water-sediment systems. They should serve the estimation of persistence indicators for hazard assessment and half-lives for exposure modeling. Although dissipation half-lives of the parent compound are directly extractable from OECD 308 data, they are system-specific and mix up phase transfer with biotransformation. In contrast, aerobic biotransformation half-lives should be easier to extract from OECD 309 experiments with suspended sediments. Therefore, there is scope for OECD 309 tests with suspended sediment to serve as a proxy for degradation in the aerobic phase of the more complicated OECD 308 test, but that correspondence has remained untested so far. Our aim was to find a way to extract biotransformation rate constants that are universally valid across variants of water-sediment systems and, hence, provide a more general description of the compound's behavior in the environment. We developed a unified model that was able to simulate four experimental types (two variants of OECD 308 and two variants of OECD 309) for three compounds by using a biomass-corrected, generalized aerobic biotransformation parameter (k'bio). We used Bayesian calibration and uncertainty assessment to calibrate the models for individual experimental types separately and for combinations of experimental types. The results suggested that k'bio was a generally valid parameter for quantifying biotransformation across systems. However, its uncertainty remained significant when calibrated on individual systems alone. Using at least two different experimental types for the calibration of k'bio increased its robustness by clearly separating degradation from the phase-transfer processes taking place in the individual systems. Overall, k'bio has the potential to serve as a system-independent descriptor of aerobic biotransformation at the water-sediment interface that is equally and consistently applicable for both persistence and exposure assessment purposes.

Aspergillus fumigatus and mesophilic moulds in air in the surrounding environment downwind of non-hazardous waste landfill sites.

Non-hazardous waste landfilling has the potential to release biological agents into the air, notably mould spores. Some species, such as Aspergillus fumigatus, may be a cause of concern for at-risk nearby residents. However, air concentration in the surrounding environment of non-hazardous waste landfill sites is poorly documented. An extensive sampling programme was designed to investigate the relationship between culturable mesophilic moulds and A. fumigatus concentrations in air and distance downwind of non-hazardous waste landfill sites. On-site and off-site repeated measurements were performed at four landfill sites during cold and warm seasons. A high-flow air-sampler device was selected so as to allow peak concentration measurement. Linear mixed-effects models were used to explain variability in the concentrations in air over time and across sites, seasons, instantaneous meteorological conditions and discharged waste tonnage. Concentrations of mesophilic moulds and A. fumigatus at off-site upwind sampling locations were compared with concentrations at each of the downwind sampling locations. At the tipping face location, peak concentration reached 480,000CFUm(-3) for mesophilic moulds and 9300CFUm(-3) for A. fumigatus. Compared with upwind background levels, these concentrations were, on average, approximately 20 and 40 times higher respectively. A steep decline in the concentration of both mesophilic moulds and A. fumigatus was observed between the tipping face location and the downwind property boundary (reduction by 77% and 84% respectively), followed by a low decline leading to a 90% and 94% reduction in concentration at 200m from the property boundary and beyond. With the 200m and 500m downwind sampling point values added together, the 97.5th percentile of concentration was 6013CFUm(-3) and 87CFUm(-3) for mesophilic moulds and A. fumigatus, respectively. Other determining factors were the discharged waste tonnage, the season, instantaneous temperature and wind velocity for mesophilic mould, and instantaneous temperature for A. fumigatus. At 200m and 500 downwind from the property boundary, mesophilic moulds and A. fumigatus concentrations were still higher than the local background level. However, whilst statistically significant, this increase does not suggest an excess risk to nearby residents' health when compared with the wide range of outdoor background levels reported in literature. These findings suggest that moulds and A. fumigatus may be transported beyond 200m from the property boundary in concentrations above those found locally upwind of the landfill site. Nevertheless, for exposure assessment purposes, comparison should also be made with background levels in wider areas which are either residential or through which people travel to work for example.

Concentrations of Polybrominated Diphenyl Ethers, Hexabromocyclododecanes and Tetrabromobisphenol-A in Breast Milk from United Kingdom Women Do Not Decrease over Twelve Months of Lactation.

Conflicting evidence exists about whether concentrations of persistent organic chemicals in human milk decrease over the course of lactation. This has implications for the timing of sampling human milk for exposure assessment purposes. We examined this issue by measuring concentrations of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), the HBCD degradation products tetrabromocyclododecenes (TBCDs), and tetrabromobisphenol-A (TBBP-A) in human milk collected in 2010-2011 from 10 first-time mothers from Birmingham, UK. To evaluate whether concentrations varied significantly over the first 12 months postpartum, 12 samples were taken-one per month-from each mother, amounting to 120 samples overall. While concentrations of most of our target contaminants displayed no significant variation (p > 0.1) over the duration of our study, significant increases were detected in concentrations of ∑TBCDs (p = 0.029, average increase 1.4%/month) and BDE-153 (p = 0.058, average increase 4.2%/month). When compared to data obtained from a different set of UK mothers from a related but geographically wider catchment area sampled contemporaneously to this study, the ratio of median concentrations of BDE-153 to BDE-99 was markedly lower in the current study (0.46 compared to 1.32). This may reflect unidentified differences in exposure of the participants in the two studies.

Risk of Children’s Dermal Exposure to Galaxolide through Personal Care Products

Galaxolide is the most used fragrance since the early 1990s, and it has been largely detected in environmental and biological matrices. This polycyclic musk is present in almost all of our daily products, so the risk of human exposure is substantial, as it had been proved by its detection in human tissues and fluids. Due to the lack of information about the concentrations found in consumer products, monitoring data is needed for exposure assessment purposes. Dermal contact, mostly by personal care products, seems to be the major route of human exposure to galaxolide, and, due to the immaturity of young children’s skin, exposure consequences can be worse in this population. The main objective of this study was to evaluate galaxolide levels in personal care products used by children of Oporto (Portugal), aged 0–5 years, and relate it with consumer habits. Consumer patterns were obtained through 250 questionnaires to caregivers of Oporto children. The 79 most used products were extracted by a dispersive solid phase extraction methodology known as QuEChERS and galaxolide was determined by High Performance Liquid Chromatography (HPLC) with fluorescence detection. The concentrations ranged between 0.001 ± 0.001 mg·kg−1, on a baby wipe, and 300.480 ± 8.819 mg·kg−1, on glycerin soap, which may correspond to an estimated daily dermal exposure of 277.10 ± 0.02 µg·day−1 on the population of Oporto children. This value is in the range of the results observed for adults, although no information of toxicological risk for children is available.

The need for electronic noses for environmental odour exposure assessment

This paper focuses on the opportunities for using electronic noses for odour exposure assessment purposes, especially in cases where dispersion modelling is not applicable. Such cases include, for instance, those sources where a detailed characterisation and quantification of the odour emissions for every hour of the simulation time domain is particularly difficult, due to the nature of the source or to the variability of the emissions over time. In such situations, it is useful to determine odour exposure directly at receptors instead. This paper critically discusses the state of the art of electronic nose technology as far as its application to the determination of odour exposure at receptors is concerned. One example of electronic nose application to the monitoring of odours from an Italian municipal solid waste (MSW) landfill is reported, in order to discuss the instrument's potential and limits. The monitoring results are represented by the number of measures that are classified in a specific olfactory class; this information allows the odour exposure at each monitoring site in terms of odour detection frequency to be determined. Besides a quantification of the odour episodes, electronic noses allowed the identification of the landfill gas as the monitored landfill major odour source.

Human dermal exposure to galaxolide from personal care products

Musks are synthetic fragrances applied on personal care and household products as fixatives, by retarding the release of other fragrances with higher volatility. Galaxolide is the most used polycyclic musk since the 90th decade, and it has been detected in several environmental and biological matrices, particularly in human tissues and fluids. For exposure assessment purposes, large-monitoring data need to be obtained and rapid but reliable analytical techniques are requested. The main objective of this study is to develop and validate a new and fast analytical methodology to quantify galaxolide in personal care products and to apply this method to real matrices like skin care products (creams and lotions), shower products (soap bar), hair care products (shampoo and hair conditioner) and oral care products (toothpaste), to evaluate the human dermal exposure risk. A dispersive solid-phase extraction is proposed, using QuEChERS methodology, followed by HPLC with fluorescence detection. Some extraction parameters were studied, like the ratio of sample/solvent amounts, the homogenization time, the salt addition effect and the used sorbents. The validation parameters of the developed method were the following: a linearity range of 0.005-1.002 mg kg⁻¹ sample, a limit of detection of 0.001 mg kg⁻¹ sample, repeatability between 0.7% and 11.3% (variation coefficient of six standard injections), an intermediate precision of 2.5% (variation coefficient of six independent analysis of the same sample), mean recoveries ranging from 65% (soap bar) to 95% (body cream) and 3% of global uncertainty in most of the working range. The time of analysis, including the extraction steps, is 60 min, allowing a throughput of 4 samples h⁻¹ . Galaxolide was detected in all of the seven analysed products in concentrations ranging from 0.04 ± 0.01 mg kg⁻¹ sample (toothpaste) to 280.78 ± 8.19 mg kg⁻¹ sample (perfumed body cream), which may correspond to a significant estimated daily human dermal exposure of 904 μg day⁻¹.

Migration of silver from commercial plastic food containers and implications for consumer exposure assessment

Food storage containers with embedded silver as an antibacterial agent promise longer durability of food. For risk assessment the release of this silver into the stored food and resulting human exposure need to be known. For the purpose of exposure assessment, silver migration from commercial plastic containers with declared content of ‘nano-’ or ‘micro-silver’ into different food simulants (water, 10% ethanol, 3% acetic acid, olive oil) was quantitatively determined by ICP-MS and the form of the released silver was investigated. The highest migration of silver was observed for the acidic food simulant with 30 ng silver cm−2 contact surface within 10 days at 20°C. In a second and third use cycle, migration dropped by a factor of up to 10, so that the maximum cumulated release over three use cycles was 34 ng cm−2. The silver release over time was described using a power function and a numerical model that simulates Fickian diffusion through the plastic material. The released silver was found to be in ionic form, but also in the form of silver nanoparticles (around 12%). Consumer exposure to the total amount of silver released from the food containers is low in comparison with the background silver exposure of the general population, but since natural background concentrations are only known for ionic silver, the exposure to silver nanoparticles is not directly comparable with a safe background level.

Field application of SPME as a novel tool for occupational exposure assessment with inhalational anesthetics

Occupational exposure to inhalational anesthetics occurs routinely in operating rooms. It could induce serious health hazards and diseases. This exposure assessment is a crucial step in determining risks. In this study, a pen-shaped holder for solid-phase microextraction (SPME) sampler was successfully applied as a time-weighted average sampling tool for workshift exposure assessment of operation room staff to halothane. It proved to be very convenient for use in occupational environments such as operation rooms. Samples were analyzed by a gas chromatography-mass spectrometry. The validity of the SPME method was checked in real-world conditions with Occupational Safety and Health Administration (OSHA) 103 standard method for the determination of inhalational anesthetics. A good agreement between OSHA 103 and SPME methods was obtained and results demonstrated no statistically significant differences in anesthetic concentrations determined by the two analytical methods (p ≥ 0.05). It is concluded that SPME in retracted mode could successfully be applied in occupational exposure assessment purposes.

Organic Contamination of Settled House Dust, A Review for Exposure Assessment Purposes

People spend a considerable amount of time indoors. As a result, exposure to indoor contaminants is of great concern, notably via settled dust ingestion in particular for infants and toddlers. This paper proposes a critical review on the organic contamination of settled house dust and human exposure over the past 10 years and focused on sources, contaminations and measurement methods (sampling, pretreatment, storage and analysis). As many compounds were identified, arises the question of which ones to consider. Sensitive and selective analytical methods for simultaneous determination of targeted substances should be developed and evaluated. Various methods were described for sampling and sample preparation. Harmonization and standardization are needed to enable comparison of results from similar studies. Finally, an integrated multipollutant and multicompartment (settled dust, suspended particles and air) approach appears essential in order to determine the extent of the threat to public health posed by indoor contaminants.

Modelling the Time Profiles of Organic Solvent Concentrations for Occupational Exposure Assessment Purposes

Confronted by variable exposure scenarios characterized by intermittent concentration peaks, our study aimed to develop methods and determine mathematical functions reproducing organic solvent concentration profiles in order to assess health risks. Two similar repetitive decanting tasks using either formalin or toluene (TOL) were studied at a teaching hospital pathology laboratory. Real-time air monitoring performed in the immediate vicinity of pollutant sources over a 1-year period identified intermittent concentration peaks. In order to describe these specific exposure profiles, two different methods were used. In a first descriptive approach, concentration peaks were either assimilated to an equivalent series of rectangle functions or described by a mathematical bell-shaped function. As an alternative approach, a model based on the schedule of decanting tasks was constructed. To this end, a time-varying emission function was incorporated into three deterministic exposure models of increasing complexity (well-mixed room, two-zone, spherical turbulent diffusion) and field-derived emission parameters were estimated by fitting model outputs to measured concentration profiles. Real-time measurements revealed highly variable concentration profiles, consisting of 1-8 peaks ranging from 5 to 220 s per decanting task, and average concentrations within peaks varying over 1-2 orders of magnitude. Acceptable fits were obtained by both descriptive approaches. The tested emission function seemed relevant in reproducing intermittent pollutant releases. Only advanced models (two-zone and diffusion) gave satisfying fits within assigned input parameter ranges. Average emission rate estimates varied in the range 10-47 mg min(-1) for formaldehyde and 360-1780 mg min(-1) for TOL, depending on the model tested. Both descriptive approaches and deterministic models accurately reproduced the patterns of measured concentration peaks. However, only deterministic models provided an understanding of the relations between pollutant releases, air movements, and the resulting concentrations and may thus be recommended for exposure variability assessment purposes.