Spatial and temporal RF electromagnetic field exposure of children and adults in indoor micro environments in Belgium and Greece

Personal radio frequency electromagnetic field (RF-EMF) exposure, or exposimetry, is gaining importance in the bioelectromagnetics community but only limited data on personal exposure is available in indoor areas, namely schools, crèches, homes, and offices. Most studies are focused on adult exposure, whereas indoor microenvironments, where children are exposed, are usually not considered. A method to assess spatial and temporal indoor exposure of children and adults is proposed without involving the subjects themselves. Moreover, maximal possible daily exposure is estimated by combining instantaneous spatial and temporal exposure. In Belgium and Greece, the exposure is measured at 153 positions spread over 55 indoor microenvironments with spectral equipment. In addition, personal exposimeters (measuring EMFs of people during their daily activities) captured the temporal exposure variations during several days up to one week at 98 positions. The data were analyzed using the robust regression on order statistics (ROS) method to account for data below the detection limit. All instantaneous and maximal exposures satisfied international exposure limits and were of the same order of magnitude in Greece and Belgium. Mobile telecommunications and radio broadcasting (FM) were most present. In Belgium, digital cordless phone (DECT) exposure was present for at least 75% in the indoor microenvironments except for schools. Temporal variations of the exposure were mainly due to variations of mobile telecommunication signals. The exposure was higher during daytime than at night due to the increased voice and data traffic on the networks. Total exposure varied the most in Belgian crèches (39.3%) and Greek homes (58.2%).     

Evaluation of RF electromagnetic field exposure levels from cellular base stations in Korea

This article presents the measurement results of human exposure to CDMA800 and CDMA1800 signals at locations in Korea where the general public has expressed concern. Measurements were performed at 50 locations across the country to compare the electromagnetic field levels with the general public exposure compliance limits. At each site, the distances between the nearest single or co‐located base station and measurement positions were within a range of approximately 32–422 m. The measured exposure levels were very low compared with the international standard and the Korean human protection notice. The highest field level was 1.5 V/m, which corresponds to 0.15% of the International Commission on Non‐Ionizing Radiation Protection (ICNIRP) guidelines for human exposure. Bioelectromagnetics 31:495–498, 2010. © 2010 Wiley‐Liss, Inc.     

High-Throughput Exposure Assessment Tool (HEAT) for exposure-based prioritization of chemicals

Abstract

High-throughput methods are now routinely used to rapidly screen chemicals for potential hazard. However, hazard-based decision-making excludes important exposure considerations resulting in an incomplete estimation of chemical safety. Models to estimate exposure exist, but are generally unsuited to keep up with high-throughput demands. The High-Throughput Exposure Assessment Tool (HEAT) is designed to efficiently predict near-field exposure to consumers and workers via inhalation, oral and dermal routes. HEAT is based on well-known modeling algorithms and provides default model parameters to support reasonably conservative exposure estimates. Underlying chemical-specific data are uploaded or entered by the end user. HEAT’s main strength is the flexible tiered screening functionality, which enables exposure estimates for single or multiple chemicals simultaneously. Hypothetical case examples highlighting the application of HEAT to more complex exposure estimates for alternative and aggregate assessments are provided.     

Health Risk Assessment of Lead in the Republic of Korea

The purpose of this study was to estimate the daily exposure to lead due to food ingestion, air inhalation, and soil ingestion in the Republic of Korea's general population, and to evaluate the level of risk associated with the current lead exposure level using the proportional daily dose (3–4 μg/kg body weight/day) corresponding to the Provisional Tolerable Weekly Intake (PTWI) suggested by the Joint FAO/WHO Expert Committee on Food Additives as the toxicological tolerance level. The estimation of the daily exposure to lead via three pathways including food, soil ingestion and air inhalation was conducted as a chronic exposure assessment. For the lead exposure assessment through dietary intake, 1,389 lead residue data for 45 commodities investigated by the Korea Food and Drug Administration during the period 1995–2000 were utilized (KFDA 1996, 1997, 1998). Six hundred seventy-two air monitoring data from 7 major cities during the period 1993–2000 and 4,500 soil residue data at 1,500 sites during the period 1999–2001 were considered for the lead exposure assessment involving air inhalation and soil ingestion, respectively. The total daily exposure to lead was estimated by combining dietary intake, inhaled amount and soil intake corresponding to the typical activity of the general population, which was treated as a group of adults with a body weight of 60 kg. For risk characterization, the daily exposure to lead was compared with the toxicological tolerance level. The level of risk due to lead exposure was calculated using the hazard ratio (HR). The dietary intake of lead was 9.71 × 10_?4 mg/kg/day and the total daily exposure level, including air inhalation and soil ingestion, was 9.97 × 10_?4 mg/kg/day. The exposure contributions of foods, air and soil induced from the percentage of each media to the total daily exposure were 97.4%, 2.1% and 0.5%, respectively. Of the different commodity groups, the highest contribution to the total exposure came from grain, which represented 47.7% of the total. Additional exposure to lead occurs in certain population groups due to the use of tobacco, alcoholic beverages, and the intake of other foods, all factors not considered in this study. Through the comparison of the daily exposure to lead with the tolerance level based on the PTWI, the hazard ratio was estimated as being 0.25–0.33. This value implies that no increase in blood lead level is to be expected in the general population at the current lead exposure levels.     

The pattern of exposure to static magnetic field of nurses involved in activities related to contrast administration into patients diagnosed in 1.5 T MRI scanners

Static magnetic fields (SMFs) and time-varying electromagnetic fields exposure is necessary to obtain the diagnostic information regarding the structure of patient's tissues, by the use of magnetic resonance imaging (MRI) scanners. A diagnostic procedure may also include the administration of pharmaceuticals called contrast, which are to be applied to a patient during the examination. The nurses involved in administering contrast into a patient during the pause in examination are approaching permanently active magnets of MRI scanners and are exposed to SMF. There were performed measurements of spatial distribution of SMF in the vicinity of MRI magnets and parameters of personal exposure of nurses (i.e. individual exposimetric profiles of variability in time of SMF affecting the nurse who is performing tasks in the vicinity of magnet, characterized by statistical parameters of recorded magnetic flux density affecting the nurse). The SMF exposure in the vicinity of various MRI magnets depends on both magnetic flux density of the main field B ₀ (applicable to a patient) and the construction of the scanner, but the most important factor determining the workers' exposure is the work practice. In the course of a patient's routine examination in scanners of B ₀ = 1.5 T, the nurses are present over ～0.4–2.9 min in SMF exceeding 0.03% of B ₀ (i.e. 0.5 mT), but only sometimes they are present in SMF exceeding 5% of B ₀ (i.e. 75 mT). When patients need more attention because of their health status/condition, the nurses' exposure may be significantly longer – it may even exceed 10 min and 30% of B ₀ (i.e. 500 mT). We have found that the level of exposure of nurses to SMF may vary from < 5% of the main field (a median value: 0.5–1.5%; inter-quartile range: 0.04–8.8%; max value: 1.3–12% of B ₀) when a patient is moved from the magnets bore before contrast administration, up to the main field level (B ₀) when a patient stays in the magnets bore and nurse is crawling into the bore.     

Millimeter wave power density in aqueous biological samples

Power density distribution inside a water sample placed between two parallel lossy dielectric plates (Polystyrene) was calculated using Fresnel equations for the frequency range of 42.25-53.57 GHz. Due to the multiple internal reflections from the sample boundaries, the distribution of the power density within the thin sample is more uniform than that within a semi-infinite medium. The power density in a sample depends on the thicknesses of the sample and the adjacent dielectric plates. For the given frequency range the sample thickness optimal for power density uniformity varies between 0.28 and 0.33 mm. The front plate has a significant effect on the magnitude of the power density within the sample but little effect on the power density distribution. The thicker the rear plate, the greater is the non uniformity of the power density distribution within the sample. Based on the calculated data, we determined the dimension of an exposure chamber providing the optimal power density distribution uniformity for mm-wave irradiation.     

Exposure risks to pesticide applicators posed by the use of electric backpack sprayers and stretcher-mounted sprayers in orchards

Abstract

The introduction of the pesticide registration system in pesticide risk assessments has promoted the scientific and safe use of pesticides, and the assessment of occupational exposure risk. In the present study, we performed an experiment in a citrus orchard subject to normal orchard management practices. By measuring the exposure of applicators’ (farmers and technicians) body parts to 45% malathion emulsifiable concentrate during its application using electric backpack sprayers (0.25?KPa) and stretcher-mounted sprayers (1.5?KPa), the unit exposure (UE) was determined. The risks of exposure for pesticide applicators who adopted five different protective measures (A: no personal protective equipment (PPE), i.e., no clothes, no gloves, no caps, and no socks; B: short-sleeved top and shorts; C: short-sleeved top, shorts, and a single pair of gloves; D: short-sleeved top, shorts, a single pair of gloves, and a cap; E: long-sleeved top, long pants, a single pair of gloves, and a cap) were also assessed. The results were as follows: 1) The total levels of exposure for pesticide applicators using electric backpack sprayers and stretcher-mounted sprayers were 3613.63?µg and 5654.28?µg, respectively. When electric backpack sprayers were used, the body parts that had the highest exposure were the head (13.8%), hands (19.9%) and back (14.0%), and when stretcher-mounted sprayers were used, the hands (32.5%) and lower legs (21.1%) had the highest level of exposure; 2) In the absence of PPE, the UE values for farmers who used electric backpack sprayers and farmers who used stretcher-mounted sprayers were significantly different. However, when PPE was used, the difference in UE values between the farmers using the two different types of sprayers was not significant; 3) When protective measure A was adopted, the risk quotient (RQ) values of the farmers and technicians who used electric backpack sprayers for the application of malathion were 1.44 and 0.54, respectively; the corresponding RQ values when protective measure B was adopted were 0.97 and 0.28, respectively. When stretcher-mounted sprayers were used for the application of chlorpyrifos, the RQ value of the farmers who adopted protective measure E was 0.43 while other types of PPE use resulted in RQ values greater than 1. In contrast, the RQ value for technicians was 1.62 when protective measure A was used and 1.02 when protective measure B was adopted, whereas other types of PPE use resulted in RQ values less than 1. Therefore, besides increasing the awareness of personal protection among pesticide applicators, improvement in the management of pesticide use and the enhancement of standard operations are of practical significance for controlling occupational exposure to pesticides.     

The role of autophagy in the pathogenesis of exposure keratitis

Incomplete tear film spreading and eyelid closure can cause defective renewal of the ocular surface and air exposure‐induced epithelial keratopathy (EK). In this study, we characterized the role of autophagy in mediating the ocular surface changes leading to EK. Human corneal epithelial cells (HCECs) and C57BL/6 mice were employed as EK models, respectively. Transmission electron microscopy (TEM) evaluated changes in HCECs after air exposure. Each of these models was treated with either an autophagy inhibitor [chloroquine (CQ) or 3‐methyladenine (3‐MA)] or activator [Rapamycin (Rapa)]. Immunohistochemistry assessed autophagy‐related proteins, LC3 and p62 expression levels. Western blotting confirmed the expression levels of the autophagy‐related proteins [Beclin1 and mammalian target of rapamycin (mTOR)], the endoplasmic reticulum (ER) stress‐related proteins (PERK, eIF2α and CHOP) and the PI3K/Akt/mTOR signalling pathway‐related proteins. Real‐time quantitative PCR (qRT‐PCR) determined IL‐1β, IL‐6 and MMP9 gene expression levels. The TUNEL assay detected apoptotic cells. TEM identified autophagic vacuoles in both EK models. Increased LC3 puncta formation and decreased p62 immunofluorescent staining and Western blotting confirmed autophagy induction. CQ treatment increased TUNEL positive staining in HCECs, while Rapa had an opposite effect. Similarly, CQ injection enhanced air exposure‐induced apoptosis and inflammation in the mouse corneal epithelium, which was inhibited by Rapa treatment. Furthermore, the phosphorylation status of PERK and eIF2α and CHOP expression increased in both EK models indicating that ER stress‐induced autophagy promoted cell survival. Taken together, air exposure‐induced autophagy is indispensable for the maintenance of corneal epithelial physiology and cell survival.     

Effects function analysis of ELF magnetic field exposure in the electric utility work environment

The incomplete understanding of the relation between power-frequency fields and biological responses raises problems in defining an appropriate metric for exposure assessment and epidemiological studies. Based on evidence from biological experiments, one can define alternative metrics or effects functions that embody the relationship between field exposure patterns and hypothetical health effects. In this paper, we explore the application of the “effects function” approach to occupational exposure data. Our analysis provides examples of exposure assessments based on a range of plausible effects functions. An EMDEX time series data set of ELF frequency (40–800 Hz) magnetic field exposure measurements for electric utility workers was analyzed with several statistical measures and effects functions: average field strength, combination of threshold and exposure duration, and field strength changes. Results were compared for eight job categories: electrician, substation operator, machinist, welder, plant operator, lineman/splicer, meter reader, and clerical. Average field strength yields a different ranking for these job categories than the ranks obtained using other biologically plausible effects functions. Whereas the group of electricians has the highest exposure by average field strength, the group of substation operators has the highest ranking for most of the other effects functions. Plant operators rank highest in the total number of field strength changes greater than 1 μT per hour. The clerical group remains at the lowest end for all of these effects functions. Our analysis suggests that, although average field strength could be used as a surrogate of field exposure for simply classifying exposure into “low” and “high,” this summary measure may be misleading in the relative ranking of job categories in which workers are in “high” fields. These results indicate the relevance of metrics other than average field strength in occupational exposure assessment and in the design and analysis of epidemiological studies. Bioelectromagnetics 18:365–375, 1997. © 1997 Wiley-Liss, Inc.     

Adult Dermal Sediment Loads Following Clam Digging in Tide Flats

Sediment contamination is common and assessment of potential dermal exposure to sediments is of interest to risk assessors. However, few measurements of coastal sediment (as opposed to terrestrial soil) adherence to skin have been reported in the literature. Results are reported here for sediment loads on the skin of 18 adults engaged in clam digging for periods of up to 90 minutes in a tide flat in Rhode Island. Post-activity geometric mean loads were 0.02, 0.12, 0.16, 0.58 and 0.88 mg/cm² on faces, forearms, lower legs, feet and hands, respectively. Pre-activity loadings were less than 0.01 mg/cm² on all body parts except feet. These results are similar to very limited previously reported data obtained from four persons gathering reeds for basketry in a tide flat in Washington State.     

Survey of residential 50 Hz EMF exposure from transformer stations

In Hungary it is typical that 10/04 kV transformer stations are being installed in multistory residential and office buildings. Magnetic fields (MFs) up to several tens of microT have been measured in apartments close to transformers. The aim of the present study was to provide systematic assessment of MF exposure of residents living above transformer stations. Out of 41 addresses provided by the electricity supplier, current load of 21 transformers and MF in 21 apartments was measured. Spot MFs at 1 m height and time weighted average 24 h MF exposure at bed height was measured. All-day personal MF exposure was measured at waist and HOME exposure was calculated. BED exposure was measured at bed height. Participants kept a time-activity diary. The time-weighted average 24 h MF exposure (3.03 microT) exceeded the usual residential exposure (<0.2 microT). The mean HOME and BED personal exposure above transformers was 0.825 and 1.033 microT, respectively. Our study provides exposure assessment of a cohort with a wider exposure range, compared to power-line epidemiological studies.     

Correlations among indices of electric and magnetic field exposure in electric utility workers

Power-frequency electric and magnetic fields are known to exhibit marked temporal variation, yet in the absence of clear biological indications, the most appropriate summary indices for use in epidemiologic studies are unknown. In order to assess the statistical patterns among candidate indices, data on 4383 worker-days for magnetic fields and 2082 worker-days for electric fields collected for the Electric and Magnetic Field Project for Electric Utilities using the EMDEX meter [Bracken (1990): Palo Alto, CA: Electric Power Research Institute] were analyzed. We examined correlations at the individual and job title group levels among indices of exposure to both electric and magnetic fields, including the arithmetic mean, geometric mean, median, 20th and 90th percentiles, time above lower cutoffs of 20 V/m and 0.2 μT, and time above higher cutoffs of 100 V/m and 2.0 μT. For both electric and magnetic fields, the arithmetic mean was highly correlated with the 90th percentile; moderately correlated with the geometric mean, median, and lower and higher cutoff scores; and weakly correlated with the 20th percentile. Electric and magnetic field indices were generally weakly correlated with one another. Rank-order correlation coefficients were consistently greater than product-moment correlation coefficients. Job title group summary scores showed higher correlations among electric field indices and magnetic field indices and between electric and magnetic field indices than was found for individual worker-days, with only the 20th percentile clearly independent of the others. These results suggest that individuals' exposures are adequately characterized by a measure of central tendency for electric and magnetic fields, such as the arithmetic or geometric mean, and an indicator of a lower threshold or cutoff for each field type, such as the 20th percentile or proportion of time above 20 V/m or 0.2 μT. A single measure of central tendency for each type of field appears to be adequate when exposures are assessed at the job title level. © 1994 Wiley-Liss, Inc.     

Ochratoxin A levels in blood serum of Czech women in the first trimester of pregnancy and its correspondence with dietary intake of the mycotoxin contaminant

Abstract

The mycotoxin ochratoxin A (OTA) can elicit a wide range of toxic properties including embryotoxicity and teratogenicity. OTA crosses the placenta at early gestation rather than in late gestation, maternal OTA exposure may represent a risk for the developing fetus. The study focuses on the assessment of OTA intake of pregnant women (aged 19–40 years) in the first trimester of pregnancy by means OTA levels in 100 blood serum samples by high-performance liquid chromotography with fluorescence detection (HPLC-FD) method and comparison with dietary OTA exposure in pregnant women. Of all, 96% tested serum samples were positive with values ranging from 0.1 to 0.35?µg/l with a mean value of 0.15?µg/l.     

Measurement of the individual exposure to 50 and 16 2/3 Hz magnetic fields within the Bavarian population.

This study investigates the individual magnetic field exposures at 16 2/3 and 50 Hz of 1952 people, selected from the Bavarian population. Personal flux density meters ("Field Watcher FW2A") were worn by the participants for 24 h. Every second, the flux density was recorded for both frequencies and for the three spatial axes (dynamic range per axis: several nT up to 100 microT at 50 Hz, 150 microT at 16 2/3 Hz). For 50 Hz fields, the mean of the 1,952 individual means was 0.101 microT and that of the individual medians was 0.047 microT. High level exposures occurred mainly during working hours. Only 2.4% of the subjects showed individual medians higher than 0.2 microT. About 53% of all volunteers were working on the day of recording. Levels for craftsmen (n = 148; mean individual mean: 0.166 microT) were generally higher than those for office workers (n = 624; mean individual mean: 0.107 microT). Flux densities exceeding 100 microT at 50 Hz were measured in 31 persons. The total time with such extreme exposures amounts to nearly 21 min, less than 0.001% of the total time for all measurements (5.3 years). To our knowledge, this is the first exposure study where 16 2/3 Hz magnetic fields (caused by electrified railways) have additionally been monitored over 24 h. For persons living next to railway lines, the mean individual mean (0.156 microT) and mean individual median (0.102 microT) were calculated. Over all, the mean exposures are only 0.1% of the magnetic flux density limit for 50 Hz (100 microT) and about 0.05% of the limit (300 microT) for 16 2/3 Hz recommended by the International Commission on Non-Ionizing Radiation Protection.     

Dietary Exposure to PCDD/Fs Through Animal Products in a Highly Polluted Area in Turkey

We present an estimation of dietary exposure to PCDD/Fs by animal products in Kocaeli, a highly polluted area in Turkey, based on current food data consumption. The calculation of the PCDD/F intakes by an exposure methodology concerning consumption habits of different receptor groups in Kocaeli was included. The data relate to the PCDD/F levels in food groups of animal origin (milk, egg, meat, chicken, and fish), food consumption rates, and the fractions of locally grown foods in total consumption were statistically assessed. Monte Carlo simulation was used to estimate the ranges of PCDD/F doses through the consumption of animal products. The PCDD/F intakes through the consumption of animal products were calculated to average between 0.4–1.8 pg WHO-TEQ.kg^?1 bodyweight (bw).day^?1. The results are within the range of 1–4 pg WHO-TEQ.kg^?1 bw.day^?1, proposed as the tolerable daily intake by the World Health Organization. On the other hand, contributions of the consumption of different foods to the total PCDD/F intake and the results of sensitivity analysis showed that the PCDD/F intake in semi-urban and rural settings was determined primarily by the consumption of milk products, while consumption of meat and fish had a greater importance in urban settings.     

RF personal exposimetry on employees of elementary schools, kindergartens and day nurseries as a proxy for child exposures

Personal RF exposimetry has been in the focus of the bioelectromagnetics community in the last few years. With a few exceptions, exposimetry studies focused on adults, because measuring the exposure of children, one of the most important target groups, introduces many complications.The main feature of our study is to select teachers and kindergarten caretakers as volunteers. They are expected to receive similar exposure patterns as the children because they spend the workday close to them. Thus they can stand as proxies for estimation of exposures of children.Volunteers belonging to one of two groups (elementary school teachers, n = 31; employees of kindergartens and day nurseries, n = 50) in Hungarian cities received a Personal Exposimeter (PEM) for 24 h each. Only workdays, when the volunteers worked near children, were considered. 51 additional volunteers (office workers) were measured as controls.The volunteers wore the PEMs on their bodies. Those activities marked in the exposure diaries as work were further classified into 5 categories based on the level of certainty that they actually worked near children during that activity. Subsets of the full dataset were derived and compared based on this categorization.It was found that relaxation of the selection criteria often under- or overestimates exposure. The differences of estimation depend on the frequency band and sub-population: the kindergarten and teacher groups differ in this regard. For most frequency bands the majority of data points was below the detection limit. Derived child exposures are comparable to the worktime exposure of adults (control group).     

Evaluation of Potential Exposure to Metals in Laundered Shop Towels

We reported in 2003 that exposure to metals on laundered shop towels (LSTs) could exceed toxicity criteria. New data from LSTs used by workers in North America document the continued presence of metals in freshly laundered towels. We assessed potential exposure to metals based on concentrations of metals on the LSTs, estimates of LST usage by employees, and the transfer of metals from LST-to-hand, hand-to-mouth, and LST-to-lip, under average- or high-exposure scenarios. Exposure estimates were compared to toxicity criteria. Under an average-exposure scenario (excluding metals’ data outliers), exceedances of the California Environmental Protection Agency, U.S. Environmental Protection Agency, and the Agency for Toxic Substances and Disease Registry toxicity criteria may occur for aluminum, cadmium, cobalt, copper, iron, and lead. Calculated intakes for these metals were up to more than 400-fold higher (lead) than their respective toxicity criterion. For the high-exposure scenario, additional exceedances may occur, and high-exposure intakes were up to 1,170-fold higher (lead) than their respective toxicity criterion. A sensitivity analysis indicated that alternate plausible assumptions could increase or decrease the magnitude of exceedances, but were unlikely to eliminate certain exceedances, particularly for lead.     

Adult onset acute myelogenous leukemia and electromagnetic fields in Los Angeles County: bed-heating and occupational exposures

In a large matched population-based case-control study of acute myelogenous leukemia (AML), we did not find incident AML in Los Angeles County (1987-1994) to be associated with previous exposure to electric blankets, electrically heated waterbeds, or occupations with presumed high exposure to electromagnetic fields.