Reference Levels For Exposure Research Articles

An Alternative Approach for Evaluating Induced and Contact Currents for Compliance with Their Exposure Limits (100 kHz to 110 MHz) in IEEE Std C95.1-2019.

The Institute of Electrical and Electronics Engineers establishes exposure reference levels (ERLs) for electric fields (E-fields) (0-300 GHz) and both induced (IIND) and contact currents (ISC) (<110 MHz) in its standard, IEEE Std C95.1™-2019 (IEEE C95.1). The "classical" scenarios addressed in IEEE C95.1 include a free-standing, grounded "reference" person (IIND) or an ungrounded reference person in manual contact with an adjacent grounded conductor (ISC), each exposed to a vertically oriented E-field driving the currents. The ERLs for current from 100 kHz to 110 MHz were established to limit heating in the finger (from touch), ankle (IIND), and wrist (ISC from grasp contact), specifying the 6-min average specific absorption rate (SAR, W kg-1) as the dosimetric reference limit (DRL); whole-body E-field ERLs are 30-min averages. The DRLs were established assuming a default "effective" local cross-section (9.5 cm2) and consistent with a composite tissue conductivity of ~0.5 S m-1. A previous publication described the misalignment of the ERLs for E-fields with the ERLs for IIND (which extends to ISC) and also proposed a ramped E-field ERL from 100 kHz to 30 MHz. For the frequency range 100 kHz to 110 MHz, this paper proposes temperature increase (ΔT) in ankle and wrist as the preferred effect metric associated with IIND and ISC; applying the E-field ERLs as surrogates for limits to these currents; and adopting the proposed ramp. The analysis of ΔT is based on the tissue mix in realistic anatomic depictions of ankle and wrist cross-sections; relevant tissue properties posted online; published tissue perfusion data; and anthropometric data on a large sample of male and female adults in the US military, allowing an estimate of effects over a range of body size. To evaluate ΔT versus frequency and time, the Penne bioheat equation was adapted with convective cooling from arterial blood as the lone cooling mechanism. The analysis revealed that IINDs and ISCs induced by ERL-level E-fields produce SARs in excess of the local DRLs (in some cases far exceed). Calculations of time to ΔT of 5 °C, reflective of a potentially adverse (painful) response, resulted in worst-case times for effects in the ankle on the order of minutes but on the order of 10s of s in wrist. Thus, compliance with the E-field ERL, as assessed as a 30-min whole-body average is incompatible with the time course of potentially adverse effects in ankle and wrist from IIND and ISC, respectively. Further analysis of the relevant exposure/dose scenarios and consensus of stakeholders with a multi-disciplinary perspective will enable the development of a revised standard, practical from a compliance perspective and protective of all persons.

Machine learning-assisted antenna modelling for realistic assessment of incident power density on non-planar surfaces above 6 GHz.

In this paper, the analysis of exposure reference levels is performed for the case of a half-wavelength dipole antenna positioned in the immediate vicinity of non-planar body parts. The incident power density (IPD) spatially averaged over the spherical and cylindrical surface is computed at the 6-90 GHz range, and subsequently placed in the context of the current international guidelines and standards for limiting exposure to electromagnetic (EM) fields which are defined considering planar computational tissue models. As numerical errors are ubiquitous at such high frequencies, the spatial resolution of EM models needs to be increased which in turn results in increased computational complexity and memory requirements. To alleviate this issue, we hybridise machine learning and traditional scientific computing approaches through differentiable programming paradigm. Findings demonstrate a strong positive effect the curvature of non-planar models has on the spatially averaged IPD with up to 15% larger values compared to the corresponding planar model in considered exposure scenarios.

PFASs: What can we learn from the European Human Biomonitoring Initiative HBM4EU.

Per- and polyfluoroalkyl substances (PFASs) were one of the priority substance groups selected which have been investigated under the ambitious European Joint programme HBM4EU (2017-2022). In order to answer policy relevant questions concerning exposure and health effects of PFASs in Europe several activities were developed under HBM4EU namely i) synthesis of HBM data generated in Europe prior to HBM4EU by developing new platforms, ii) development of a Quality Assurance/Quality Control Program covering 12 biomarkers of PFASs, iii) aligned and harmonized human biomonitoring studies of PFASs. In addition, some cohort studies (on mother-child exposure, occupational exposure to hexavalent chromium) were initiated, and literature researches on risk assessment of mixtures of PFAS, health effects and effect biomarkers were performed. The HBM4EU Aligned Studies have generated internal exposure reference levels for 12 PFASs in 1957 European teenagers aged 12-18 years. The results showed that serum levels of 14.3% of the teenagers exceeded 6.9μg/L PFASs, which corresponds to the EFSA guideline value for a tolerable weekly intake (TWI) of 4.4ng/kg for some of the investigated PFASs (PFOA, PFOS, PFNA and PFHxS). In Northern and Western Europe, 24% of teenagers exceeded this level. The most relevant sources of exposure identified were drinking water and some foods (fish, eggs, offal and locally produced foods). HBM4EU occupational studies also revealed very high levels of PFASs exposure in workers (P95: 192μg/L in chrome plating facilities), highlighting the importance of monitoring PFASs exposure in specific workplaces. In addition, environmental contaminated hotspots causing high exposure to the population were identified. In conclusion, the frequent and high PFASs exposure evidenced by HBM4EU strongly suggests the need to take all possible measures to prevent further contamination of the European population, in addition to adopting remediation measures in hotspot areas, to protect human health and the environment. HBM4EU findings also support the restriction of the whole group of PFASs. Further, research and definition for additional toxicological dose-effect relationship values for more PFASs compounds is needed.

Aligning Exposure Limits for Contact Currents with Exposure Limits for Electric Fields.

The Institute for Electrical and Electronic Engineers (IEEE) and the International Commission on Non-ionizing Radiation Protection (ICNIRP) have established limits for exposures to electromagnetic fields across the 0-300 GHz (non-ionizing) spectrum, including limits on contact currents ( CC ) specified by IEEE for 0-110 MHz (ICNIRP issued a CC "guidance level"). Both sets of limits seek to protect against potentially adverse effects, including aversive electrostimulation at frequencies <100 kHz and excessive heating of tissue at frequencies >100 kHz. For the most part, CC is linked to electric field ( E -field) exposures for an ungrounded person contacting a grounded object, with the short-circuit current ( I SC ) through the contact point (usually the hand) equivalent to the current through the grounded feet of a free-standing person exposed to a vertically polarized E -field. The physical linkage between these two quantities dictates that their respective exposure limits align with one another, which is presently not the case, especially with respect to frequencies from100 kHz to 110 MHz. Here we focus specifically on recommendations for revisions to the IEEE standard, IEEE Std C95.1™-2019 ("IEEE C95.1"), in which the E -field exposure limit ( E -field exposure reference levels, ERL s) >100 kHz induces substantially greater currents than the CC ERL s currently prescribed. The most important scenario deserving of attention concerns finger contact through a 1-cm 2 cross-sectional interface between the skin and a grounded conductor in which the rate of temperature rise in the presence of an E -field ERL can be rapid enough to cause a burn injury. This rate is highly dependent on the moistness/dryness of the skin at the contact point (i.e., its impedance)-a highly variable value-with temperature increasing more rapidly with increasing dryness (greater contact impedance). The two main remedies to alleviate the possibility of injury in this "touch" scenario are to (a) limit the time of finger contact to 1 s in all cases and (b) revise the E -field ERL between 100 kHz and 30 MHz from a "hockey-stick-shaped" curve vs. frequency to a "ramp" across this frequency range. These measures factored in with the real-world prevalence of potentially hazardous scenarios should afford greater protection against adverse outcomes than is presently the case. IEEE C95.1 also specifies limits for grasp contact (15 cm 2 in the palm) and associated wrist heating, plus heating in the ankles from free-standing induction. However, these scenarios are more manageable compared to finger touch due mainly to the comparatively lower rates of tissue heating attributable to the wrist's and ankle's relatively greater cross-sectional area. Recommendations for grasp can thus be dealt with separately. Two identified but unaddressed issues in IEEE C95.1 deserving of further attention are first, the circumstance in which a grounded person contacts an ungrounded object situated in an electric field for which there are countless numbers of scenarios that are not amenable to a single ERL . Second, arcing between an extended limb and E -field-exposed object is perhaps the most hazardous of all scenarios. Both of these scenarios cannot be stereotyped and must be dealt with on a case-by-case basis. Future revisions of IEEE Std C95.1-2019 (and the ICNIRP guidelines) will benefit from improved insight into strategies of affording protection from potentially adverse effects in these circumstances.

On the Correlation Between Incident Power Density and Temperature Increase for Exposures at Frequencies Above 6 GHz

International guidelines/standards for human exposure to electromagnetic fields have recently been revised to update the dosimetric reference limits (DRLs or basic restrictions) and exposure reference levels (ERLs), specifically for frequencies above 6 GHz. At such frequencies, the ERL is defined in terms of incident power density (IPD) and used as a practical quantity to assess compliance with DRLs (absorbed or epithelial power density) and therefore appropriately limits temperature elevation at the body surface. In the exposure standards, IPD is spatially averaged over an area of 4 cm² below 30 GHz and 1 cm² above 30 GHz, however the definition of IPD is given in a theoretical manner. With the progress in the development of product safety compliance assessment standards, one concern has been how to define the IPD considering practical measurement procedures. Two definitions or averaging methods were considered: using IPD vectors normal to the averaging surface and using magnitude (norm) of IPD vectors. As the exposure guidelines are intended to prevent excessive tissue heating, statistical analysis was therefore undertaken to investigate which IPD metric better correlates with the temperature increase. To this end, a large data set for several exposure scenarios was collected by different research institutions. The analysis of the obtained results is presented and shows that both definitions have high correlation with temperature rise, with slightly better correlation (0.9 vs. 0.8) for the definition using the magnitude of IPD vectors.

Inter-individual variations in electric fields induced in the brain by exposure to uniform magnetic fields at 50 Hz

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Institute of Electrical and Electronics Engineers (IEEE) standard establish safety limits for human exposure to electromagnetic fields. At low frequencies, only a limited number of computational body models or simplified geometrical shapes are used to relate the internal induced electric fields and the external magnetic fields. As a consequence, both standard/guidelines derive the exposure reference levels for the external magnetic field without considering the variability between individuals. Here we provide quantitative data on the variation of the maximum electric field strengths induced in the brain of 118 individuals when exposed to uniform magnetic fields at 50 Hz. We found that individual characteristics, such as age and skull volume, as well as incident magnetic field direction, have a systematic effect on the peak electric field values. Older individuals show higher induced electric field strengths, possibly due to age-related anatomical changes in brain. Peak electric field strengths are found to increase for larger skull volumes, as well as for incident magnetic fields directed along the lateral direction. Moreover, the maximum electric fields provided by the anatomical models used by ICNIRP for deriving exposure limits are considerably higher than those obtained here. On the contrary, the IEEE elliptical exposure model produces a weaker peak electric field strength. Our findings are useful for the revision and harmonization of the current exposure standard and guidelines. The present investigation reduces the dosimetric uncertainty of the induced electric field among different anatomical induction models. The obtained results can be used as a basis for the selection of appropriate reduction factors when deriving exposure reference levels for human protection to low-frequency electromagnetic exposure.

Statistical analysis of electromagnetic radiation measurements in the vicinity of GSM/UMTS base station installed on buildings in Serbia.

As a result of dense deployment of public mobile base stations, additional electromagnetic (EM) radiation occurs in the modern human environment. At the same time, public concern about the exposure to EM radiation emitted by such sources has increased. In order to determine the level of radio frequency radiation generated by base stations, extensive EM field strength measurements were carried out for 664 base station locations, from which 276 locations refer to the case of base stations with antenna system installed on buildings. Having in mind the large percentage (42 %) of locations with installations on buildings, as well as the inevitable presence of people in their vicinity, a detailed analysis of this location category was performed. Measurement results showed that the maximum recorded value of total electric field strength has exceeded International Commission on Non-Ionizing Radiation Protection general public exposure reference levels at 2.5 % of locations and Serbian national reference levels at 15.6 % of locations. It should be emphasised that the values exceeding the reference levels were observed only outdoor, while in indoor total electric field strength in no case exceeded the defined reference levels.

Application of the Monte Carlo Method for the Estimation of Uncertainty in Radiofrequency Field Spot Measurements

Abstract The objective of the present work is the application of the Monte Carlo method (GUMS1) for evaluating uncertainty in electromagnetic field measurements and the comparison of the results with the ones obtained using the 'standard' method (GUM). In particular, the two methods are applied in order to evaluate the field measurement uncertainty using a frequency selective radiation meter and the Total Exposure Quotient (TEQ) uncertainty. Comparative results are presented in order to highlight cases where GUMS1 results deviate significantly from the ones obtained using GUM, such as the presence of a non-linear mathematical model connecting the inputs with the output quantity (case of the TEQ model) or the presence of a dominant nonnormal distribution of an input quantity (case of U-shaped mismatch uncertainty). The deviation of the results obtained from the two methods can even lead to different decisions regarding the conformance with the exposure reference levels.

Radiation exposure in CT-guided interventions

PurposeTo investigate radiation exposure in computed tomography (CT)-guided interventions, to establish reference levels for exposure, and to discuss strategies for dose reduction. Materials and methodsWe analyzed 1576 consecutive CT-guided procedures in 1284 patients performed over 4.5 years, including drainage placements; biopsies of different organs; radiofrequency and microwave ablations (RFA/MWA) of liver, bone, and lung tumors; pain blockages, and vertebroplasties. Data were analyzed with respect to scanner settings, overall radiation doses, and individual doses of planning CT series, CT intervention, and control CT series. ResultsEighy-five percent of the total radiation dose was applied during the pre- and post-interventional CT series, leaving only 15% applied by the CT-guided intervention itself. Single slice acquisition was associated with lower doses than continuous CT-fluoroscopy (37mGycm vs. 153mGycm, p<0.001). The third quartile of radiation doses varied considerably for different interventions. The highest doses were observed in complex interventions like RFA/MWA of the liver, followed by vertebroplasty and RFA/MWA of the lung. ConclusionsThis paper suggests preliminary reference levels for various intervention types and discusses strategies for dose reduction. A multicenter registry of radiation exposure including a broader spectrum of scanners and intervention types is needed to develop definitive reference levels.

Concentrations of some toxic and trace elements in wild boar (Sus scrofa) organs and tissues in different areas of the Province of Viterbo (Central Italy)

The aim of the present study was to determine heavy metal reference levels for exposure and risk assessment studies on a local scale. The average levels of cadmium recorded in 75 wild boars were 0.085, 0.079 and 1.052 mg Cd kg -1 wet weight (w.w.) in the liver, muscle and kidney, respectively. The majority of the muscle samples and some of the liver samples contained levels of heavy metal that were over the legal limit [EU Maximum Residue Levels (MRLs)] for pigs. Our data are similar to or lower than the values reported in most of the available literature. For Pb concentration, the average values recorded were 0.318, 0.126 and 0.298 mg kg kg -1 ww.w. in the liver, muscle and kidney, respectively. The samples that were non-compliant with regulatory limits (MRLs) for pigs were registered only for muscle. Available data on the presence of Pb content in game meat report lower values than ours, most likely because the area around the bullet path was avoided while sampling. The average values of total Cr were 0.141, 0.139 and 0.097 mg Cr kg -1 w.w. in the liver, muscle and kidney, respectively. For Zn, the mean values were 49.76, 53.21 and 32.46 mg kg -1 w.w. in liver, muscle and kidney, respectively. Cu content was 46.12, 12.20 and 5.64 mg kg -1 w.w. in the liver, muscle and kidney, respectively. The results obtained have been validated on the basis of the scarce and inconsistent Italian literature available and on international studies.

Concentrations of some toxic and trace elements in wild boar (Sus scrofa) organs and tissues in different areas of the Province of Viterbo, Central Italy

AbThset ariamc otf the present study was to determine heavy metal reference levels for exposure and risk assessment studies on a local scale. We measured lead (Pb), chromium (Cr), zinc (Zn), copper (Cu) and cadmium (Cd) content in edible tissues and organs of wild boars harvested in different areas of the Province of Viterbo, Central Italy. The average levels of cadmium recorded in 75 wild boars were 0.085, 0.079 and 1.052 mg Cd kg−1 wet weight (w.w.) in the liver, muscle and kidney, respectively. The majority of the muscle samples and some of the liver samples contained levels of heavy metal that were over the legal limit [EU Maximum Residue Levels (MRLs)] for pigs. Our data are similar to or lower than the values reported in most of the available literature. For Pb concentration, the average values recorded were 0.318, 0.126 and 0.298 mg kg−1 w.w. in the liver, muscle and kidney, respectively. The samples that were non-compliant with regulatory limits (MRLs) for pigs were registered only for muscle. Available data on the presence of Pb content in game meat report lower values than ours, most likely because the area around the bullet path was avoided while sampling. The average values of total Cr were 0.141, 0.139 and 0.097 mg kg−1 w.w. in the liver, muscle and kidney, respectively. For Zn, the mean values were 49.76, 53.21 and 32.46 mg kg−1 w.w. in the liver, muscle and kidney, respectively. Cu content was 46.12, 12.20 and 5.64 mg Cu kg−1 w.w. in the liver, muscle and kidney, respectively. The results obtained have been validated on the basis of the scarce and inconsistent Italian literature available and on international studies.

Residential characteristics and radiofrequency electromagnetic field exposures from bedroom measurements in Germany

The objectives of this study were to assess total exposure to radiofrequency electromagnetic fields (RF-EMF) in bedrooms and the contribution of different radioservices (FM radio, analogue TV and DVB-T, TETRA, GSM900 downlink, GSM1800 downlink, UMTS downlink, DECT, and wireless LAN and blue tooth) to the total exposure. Additional aims were to describe the proportion of measuring values above the detection limit of the dosimeters and to characterize the differences in exposure patterns associated with self-reported residential characteristics. Exposure to RF sources in bedrooms was measured using Antennessa(®) EME Spy 120 dosimeters in 1,348 households in Germany; 280 measures were available for each frequency band per household. Mean electrical field strengths and power flux densities were calculated. Power flux densities allow the calculation of proportions of different radioservices on total exposure. Exposure was often below the detection limit (electrical field strength: 0.05V/m) of the dosimeter. Total exposure varied, depending on residential characteristics (urban vs. rural areas and floor of a building the measurement took place). Major sources of exposure were cordless phones (DECT standard) and wireless LAN/blue tooth contributing about 82% of total exposure (20.5μW/m(2)). Exposure to RF-EMF is ubiquitous, but exposure levels are-if at all measurable-very low and far below the ICNIRP's exposure reference levels.

Electrical stimulation vs thermal effects in a complex electromagnetic environment

Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5–2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10 − 4 ) than that based on thermal considerations (exposure quotient 0.16 10 − 4 ). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

Whole-body-averaged SAR from 50 MHz to 4 GHz in the University of Florida child voxel phantoms

The University of Florida (UF) Series B paediatric phantoms were developed for medical and radiation protection photon dosimetry. The series includes a 9 month male, a 4 year female, an 8 year female, an 11 year male and a 14 year male. In this paper they have been adapted to calculate the whole-body-averaged specific energy absorption rate (SAR) in children for plane wave exposure from 50 MHz to 4 GHz. The consideration of children is important in the application of the ICNIRP public exposure reference levels above ∼1 GHz. The uniformly scaled models of NORMAN and NAOMI suggest that the ICNIRP reference level does not provide a conservative estimate of the whole-body-averaged SAR restriction for 5 year and 1 year old models. Comparison is made with the previous linearly scaled versions of NORMAN and NAOMI for calculations at 2 mm resolution. Further FDTD calculations were performed at resolutions of 1 and 0.7 mm above 900 MHz to elucidate the effects of grid resolution on SAR. A comparison is made between the calculated external electric fields required to produce the basic restriction on the whole-body-averaged SAR and the ICNIRP reference levels for public exposure.

Magnetic emissions of electric appliances

More than 1000 electric appliances have been investigated regarding their emission of magnetic fields. It was found that complex frequency spectra are common and single frequency emissions are rare. Since exposure assessment requires frequency-weighted sums, root-mean-square values are not appropriate for comparison with exposure reference levels. It could be shown that they may underestimate emissions up to two orders of magnitude. Analysis of device groups showed a wide span of emission values of up to two orders of magnitude with only weak associations to power consumption. This demonstrates that there is a considerable potential to reduce fields without loss of performance. Exposure to magnetic fields of electric appliances are not negligible in daily life. Many devices considerably exceeded permitted reference levels and would require a closer analysis to demonstrate conformity with basic limits.

HEALTH IMPACT ASSESSMENT OF LONG TERM EXPOSURE TO FINE PARTICLES IN FRENCH CITIES

ISEE-567 Abstract: In the framework of the preparation of the National Environment Health Action Plan, a health impact assessment study was conducted in a large number of French metropolitan areas, following the rationale proposed by Künzli et al [2000]. Based on the latest international epidemiological evidence [Pope et al 2002] the number of air pollution attributable cases (lung cancer and cardiopulmonary mortality) was derived, with fine particles as single indicator of urban air pollution. Retrospective urban background PM10 concentration data were retrieved from the Ambient Air Quality National Database covering 76 Urban Units and 15 259 590 adults 30 years old and over. PM10 data were converted into PM2.5 estimates applying a 60 % PM2.5/PM10 ratio. Attributable number of deaths and potentially avoidable cases were computed for year 2002, assuming a 15 year retrospective exposure. The “no risk” baseline exposure level was ranging from 4.5μg/m3 to 9μg/m3, while the average 2002 urban background PM2.5 concentration was 12μg/m3. A set of scenarios was used to forecast ambient air concentrations over the next 20 years. The main results for lung cancer mortality, based on the lowest baseline exposure level (4.5μg/m3), are the following: In 2002, the estimated attributable number of deaths due to the previous 16 years of exposure is 670 [89-1 257]CI95%, which corresponds to an attributable fraction of 6 %. When the target for PM2.5 in year 2020 is set at 4.5μg/m3 (in the “volunteer” scenario), the estimated number of lung cancer attributable cases is 575 [76-1 084] in 2010 and 335 [43-644] in 2020. Under the assumption of a linear reduction of the annual impacts between 2002, 2010 and 2020, the potentially avoidable total number of attributable deaths until 2020 (by comparison with a situation “leave it as it is in 2002”) is 2 698. Results are also available for cardio-pulmonary mortality (figures are about 5 fold greater). A sensitivity analysis was carried out for different exposure reference levels, ambient air quality objectives and RR estimates exposed in the paper by Pope et al. Sources of uncertainty are discussed along with the impact assessment process. Results are put into perspective with a parallel output proposing some action scenarios to reduce urban air pollution levels, and associated exposures.