An historical overview of the activities in the field of exposure and risk assessment of non-ionizing radiation in Bulgaria

Abstract

The exposure and risk evaluation process in Bulgaria concerning non-ionizing radiation health and safety started in the early 1970s. Then, the first research laboratory “Electromagnetic fields in the working environment” was founded in the framework of the Centre of Hygiene, belonging to the Medical Academy, Sofia. The main activities were connected with developing legislation, new equipment for measurement of electromagnetic fields, new methods for measurement and exposure assessment, in vivo and human studies for developing methods, studying the effect of non-ionizing radiation on human body, developing exposure limits. Most of the occupations as metal industry, plastic welding, energetics, physiotherapy, broadcasting, telephone stations, computer industry, etc., have been covered by epidemiological investigations and risk evaluation. In 1986, the ANSI standard for safe use of lasers has been implemented as national legislation that gave the start for studies in the field of risk assessment concerning the use of lasers in industry and medicine. The environmental exposure studies started in 1991 following the very fast implementation of the telecommunication technologies. Now, funds for research are very insignificant, and studies in the field of risk assessment are very few. Nevertheless, Bulgaria has been an active member of the WHO International EMF Project, since 1997, and that gives good opportunity for collaboration with other Member states, and for implementation of new approach in the EMF policy for workers and people’s protection against non-ionizing radiation exposure.     

Potential human health risk assessment of cylindrospermopsin accumulation and depuration in lettuce and arugula

The cyanobacterial toxin cylindrospermopsin (CYN) has become a globally important secondary metabolite due to the negative effect it has on human and animal health. As a means of evaluating the risk of human exposure to CYN, the bioaccumulation and depuration of the toxin in lettuce (Lactuca sativa L.) and arugula (Eruca sativa Mill.) were investigated, after irrigation with contaminated water. The vegetables were irrigated for 7 days with CYN (3, 5 and 10 μg/L) contaminated water (bioaccumulation phase), and subsequently, irrigated for 7 days with uncontaminated distilled water (depuration phase). In general, the bioaccumulation of CYN in both vegetables decreased with increasing exposure concentration. Bioconcentration factor (BCF) of CYN increased with the progression of the experiment at 3.0 μg/L CYN, while the reverse occurred at 5 and 10 μg/L CYN. In arugula, BCF increased at all CYN exposure concentrations throughout the study. The depuration of CYN decreased with increasing exposure concentration but was highest in the plants of both species with the highest bioaccumulation of CYN. Specifically, in plants previously irrigated with water contaminated with 3, 5 and 10 μg/L CYN, the depuration of the toxin was 60.68, 27.67 and 18.52% for lettuce, and 47, 46.21 and 27.67% for arugula, respectively. Human health risks assessment revealed that the consumption of approximately 10 to 40 g of vegetables per meal will expose children and adults to 1.00-6.00 ng CYN/kg body mass for lettuce and 2.22-7.70 ng CYN/kg body mass for arugula. The irrigation of lettuce and arugula with contaminated water containing low CYN concentrations constitutes a potential human exposure route.     

Hazard and risk assessment of human exposure to toxic metals using in vitro digestion assay

Clean-up targets for toxic metals require that the site be “fit for purpose”. This means that targets are set with respect to defined receptors that reflect intended land-use. In this study, the likely threat of human exposure to toxic metals has been evaluated by simulating the human digestion process in vitro. The effects of key attributes (i.e. sample fraction size, pH, K_d and total metal concentrations) on the bioavailability of Cu and Ni were also investigated. Total metal concentration was the key explanatory factor for Cu and Ni bioavailability. A comparative ranking of metal concentrations in the context of tolerable daily intakes for Cu and Ni confirmed that the pH has the greatest impact on metals bioavailability. Rapid screening of key attributes and total toxic metal doses can reveal the relative hazard imposed on human, and this approach should be considered when defining threshold values for human protection.     

Human exposure and risk assessment of chromafenozide during treatment in rice fields

The potential dermal and respiratory exposure and risk assessments for an applicator were performed with chromafenozide in rice fields in Korea. Three experienced farmers of approximately the same height (168–170 cm) and weight (65–73 kg) were employed to perform the experiment. Dermal patches, gloves, socks, and masks were used to monitor the potential dermal exposure (PDE), and personal air samplers with XAD-2 resins were used to monitor the potential inhalation exposure. During the mixing/loading process of chromafenozide (2.5%, EC), the average hand exposure amount was 3.7 mg and the ratio to the applied amount was 1.85 ×10^?2%. For spraying process, the potential dermal exposure amount was 98.3 (74.5–112.8) mg, corresponding to 0.492% of the total exposure amount. The major exposure parts were thigh (0.37%) and shin (0.10%), and the left body (55.0%) was more than that of the right body (45.0%). The inhalation exposure amount was only 39.9 mg. For risk assessment, the mean of PDE (384.0 mg/day) and the mean of absorbable quantity of exposure (3.99 mg/day) were calculated. The value of margin of safety (MOS) ranged from 1.12 to 1.69, all MOS were >1, indicating the exposure level of chromafenozide was safe during application in rice fields.     

Dietary exposure and risk assessment to cadmium of the adult population of Jiangsu province,China: Comparing between semi-probabilistic and fully probabilistic approaches

With rapid industrialization and modernization in China, long-term dietary exposure to cadmium (Cd) has the potential to cause health risks. The traditional probabilistic approach for long-term dietary assessment was a semi-probabilistic method that had limitations in qualifying the variation in concentration data. Thus, this article estimated the long-term dietary exposure to Cd of the adults of Jiangsu province using semi-probabilistic and fully probabilistic approaches, and compared the two models. Cd concentration data were obtained from the national food contamination monitoring program 2001–2009. Food consumption data were gathered from the National Diet and Nutrition Survey conducted in 2002. The provisional tolerable daily intakes (PTDI) of 0.8 μg kg^–1 bw for Cd was applied in the risk assessment. The estimates of semi-probabilistic approach were within the provisional tolerable daily intakes (PTDI) at mean and all percentiles. However, the P95 of exposure with fully probabilistic approach for all population groups were above PTDI. Rice and rice products followed by wheat flour and wheat flour products, crustaceans, pak-choi, beans, and bean products contributed most to the Cd intake for adults. The fully probabilistic estimates could indicate a possible public health concern on Cd for adults in Jiangsu province.     

Finding fault with health risk assessment: A typology for risk assessment criticism

Although systematic, quantitative assessment of environmental health risks is a staple of regulatory decision-making, complaints regarding its perceived failures and shortcomings are an intrinsic feature of the policy landscape. In this article, we (a) catalog the classic criticisms of conventional health risk assessment, (b) create a typology that orders the critiques according to their focus on either input errors or output biases, and (c) identify selected allegations that fall within each category. We also note that the risk assessment–risk management paradigm has evolved over the past several decades, partially in accordance with the general direction and spirit of these classic critiques. The debate continues today along familiar lines invoking the traditional critiques and rebuttals outlined here.     

Health risk assessment of residential exposure to cypermethrin among young children in agricultural communities in northeastern Thailand

This study aimed to identify factors associated with dermal exposure to cypermethrin and assess the health risks among young children in an agricultural community in Thailand. Face-to-face interviews were conducted with the parents/caregivers of 58 children (aged 1–3 years). Wipe samples were analyzed for cypermethrin by gas chromatography-microelectron capture detection (GC-µECD). Health risk assessments were based on the cypermethrin concentration on the children’s hands and feet. Spearman’s correlation indicated significant associations among cypermethrin concentrations on the hands, feet, floors/wooden beds, and toys (rho?=?0.438–0.613, p-value <0.001). Cypermethrin concentrations on the hands were significantly and inversely correlated with the child’s caregiver being the child’s mother and insecticide use (p?<?0.01). Concentrations on the feet were significantly correlated with insecticide use (p?<?0.05) and showering (p?<?0.01). The hazard quotient calculated from dermal exposure via the hands and feet showed no risk for potential noncarcinogenic effects (5.586?×?10^?5 in the dry season and 4.301?×?10^?4 in the wet season). These findings suggest that young children might not be at risk for cypermethrin exposure through the dermal route. Residential exposure among young children may be reduced by improved hygiene. Health risk assessments of environmental insecticide exposure via the oral and inhalation routes require further investigation.     

Bioaccessibility and health risk assessment of rare earth elements in Porphyra seaweed species

In this study, the content and bioaccessibility of rare earth elements (REEs) in Porphyra spp. Samples before and after thermal treatments were investigated. Additionally, the risks of REEs exposure to human health were assessed. REEs content significantly reduced after thermal processing (P < 0.01), and the removal rate of REEs was approximately 30%. Thermal treatment increased REEs bioaccessibility from 44% to 64.34%. The concentration and bioaccessibility of Ce, La, Y, Nd were high in raw and thermally treated Porphyra samples, and there was no correlation between REEs content and bioaccessibility. Based on the following parameters: highest content of REEs in the studied seaweed samples (13.45 mg/kg), the highest daily seafood consumption (44.9 g/day), and the highest bioaccessibility (64.34%), the ratio of the calculated daily intake (DI) to daily allowable intake by diet (DAI_diet) of REEs did not exceed the reference value in rare earth mining areas or under extreme conditions. The DI via seafood consumption would be exceeded when the content of REEs in the seafood sample is greater than 15.77 mg/kg. In this study, the concentration of REEs did not exceed 15.77 mg/kg in any sample. Thus, the human health risks of REEs associated with seafood are low.     

A software tool for organ-specific second cancer risk assessment from exposure to therapeutic doses

The aim of this study was the development of a software tool (SCRcalc) for the automatic estimation of the patient- and organ-specific cancer risk due to radiotherapy. SCRcalc was developed using the Python 3.8.7 programming language. It incorporates equations and parameters of mechanistic models for the calculation of the organ equivalent dose (OED), the excess absolute risk (EA R) and the lifetime attributable risk (LA R) of carcinogenesis for various organs due to radiotherapy. Data from differential dose-volume histograms, as defined by a treatment planning system, could be automatically inserted into the program. Eighteen different cancer risk estimates for various organs were performed of patients subjected to radiation therapy with conventional and modulated techniques. These software estimates were compared with manual calculations. SCRcalc was developed as a standalone executable program without any dependencies. It enables direct estimations of the OED and LAR for various organs at risk. An important aspect of the software is that it does not require pre-processing of the DVH data. No differences were found between the SCRcalc results and those derived from manual calculations. The newly developed software offers the possibility to medical physicists and radiation oncologists to directly estimate the probability of radiotherapy-induced secondary malignancies for various organs at risk.     

Human health risk assessment of trace elements in shallow groundwater of the Linhuan coal-mining district,Northern Anhui Province,China

Enrichment of trace elements in groundwater poses considerable risks to human health. The concentrations of seven trace elements (Cr, Mn, Ni, Cu, Zn, Cd, and Pb) in 34 samples of shallow groundwater from the study area were estimated. We assessed the concentrations of the trace elements and health risks with statistical analysis and the US Environment Protection Agency (USEPA) model. The results showed that the mean concentrations of trace elements decreased as follows: Mn > Zn > Ni > Cr > Cu > Cd > Pb. Apart from Mn at one sampling point, the concentrations of all trace elements were below the guideline values of the World Health Organization for drinking water. Correlation and cluster analysis indicated that the trace elements fell into groups, with Ni and Cu in one group, and Mn, Zn, and Cd in another, which suggested that the trace elements grouped together had similar sources. The total non-carcinogenic risk values ranged from 8.52 × 10^?4 to 1.27 × 10^?1. The total carcinogenic risk caused by Cr and Cd averaged 1.62 × 10^?6, which exceeded the acceptable level of 1 × 10^?6 recommended by the USEPA. The carcinogenic risk of Cr accounted for 75.93% of R_total.     

Content and health risk assessment of selected elements in commercially available fish and fish products

Selected elements (Na, K, P, Mg, Fe, Zn, Cr, Ni, Cu, Mn, Pb, Hg) in fish and fish products bought in supermarkets in Krakow were investigated. Contents of elements were analyzed using AMA 254 apparatus for Hg, and ICP-AES method on JY238 ULTRACE apparatus after samples digestion (HNO₃+HClO₄ 3:1) for other elements. Elements’ concentrations in six fish species and fish products were within the range of (mg/kg w.m.): 2151–6239 for Na; 855–2500 for K; 49.3–183 for P; 353–531 for Mg; 32.6–61.3 for Fe; 4.01–17.6 for Zn; 7.04–12.9 for Cr; 4.25–7.98 for Ni; 1.30–2.27 for Cu; 0.99–1.51 for Mn; 0.09–0.21 for Pb; and 0.01–0.13 for Hg. Human health risk assessment revealed that total non-carcinogenic risk was low to medium with general decreasing order: tuna > salmon > herring> pollock > crab sticks > iridescent shark-catfish. The carcinogenic risk was acceptable for adults and unacceptable for children. Carcinogenic risk values for all subpopulations for Pb were decreasingly ordered as follows: tuna > salmon > herring > pollock > iridescent shark-catfish > crab sticks; and for Cr(VI): tuna > salmon > herring > pollock > crab sticks > iridescent shark-catfish.     

生态风险评价方法述评

生态风险是由环境的自然变化或人类活动引起的生态系统组成、结构的改变而导致系统功能损失的可能性。生态风险评价是定量预测各种风险源对生态系统产生风险的或然性以及评估该风险可接受程度的方法体系,因而是生态环境风险管理与决策的定量依据。在介绍了生态风险概念的基础上,按照风险源性质的分类标准将生态风险划分为化学污染类风险源、生态事件类风险源、复合类风险源3类,并分别论述了3类生态风险对应评价方法的特点与发展的方向。另外,针对生态风险评价研究的现状,讨论了我国生态风险研究的优先领域,包括建立急性、慢性毒理数据库,构建外来生物入侵风险评价标准等,同时,建议将综合概率统计学、复杂系统理论与遥感技术等手段引入生态风险评价方法中,以进一步提高风险评价结果在生态风险管理中的有效性。     

Contamination and health risk assessment of trace elements in soil at play centers of urban low-income settings

Abstract

Young children are considered critical receptors of potentially toxic trace elements (PTEs) by non-dietary ingestion of contaminated soil. The study assessed the potential enrichment of soil and the health risk of PTEs to 471 children less than seven years via non-dietary soil ingestion at six Early Childhood Development Centers (ECDCs) in urban low-income settings. The total concentrations of PTEs were determined by ICP-AES after wet acid digestion. The extent of soil contamination with PTEs and their source apportionment were assessed by the enrichment factor (EF). The US-EPA risk assessment model was used to determine the risk of PTE exposure by children. Multivariate statistical analyses and the EF suggested anthropogenic origin of PTEs in playgrounds and indoors, especially Cd and Pb from atmospheric deposition. Indoor floor dust at ECDCs was enriched (significant to extreme) with PTEs of anthropogenic origin imported from the outside environment. Children at the six ECDCs were not at significant non-carcinogenic risk of PTEs in soil and dust through non-dietary ingestion. The study setting is typical of urban child play centers in low-income countries which needs regular risk assessment and the enforcement of legislation in order to reduce the exposure of children to PTEs.     

生态风险评价及研究进展

生态风险是当前环境管理研究领域中的一个热点问题,其研究着重关注化学、物理和生物的胁迫因子可能对生态系统或其组分的有害影响.生态风险评价对科学制定环境管理决策有着重要的意义.要对生态系统进行有效地管理,必须预测不利生态影响发生的可能性及后果,减小其对于生态系统或某些组分的损害程度.本文对生态风险评价的研究方法、工具以及研究趋势进行了综述,指出了目前生态风险评价中还需要进一步加强的研究领域,认为在当前城市化水平不断提高的情况下要关注城市生态风险,并针对存在的一些问题提出了今后的研究展望.     

Basic quantitative risk assessment of light sources: Comparison of light exposure assessment and endpoint life cycle impact assessment

Human Health Area of Protection (HHAoP) has been receiving greater emphasis in recent years in the scope of Environmental Impact Assessment (EIA) of products or services with more impact categories specifically dedicated to include different dimensions of HHAoP. Human health impacts of light sources, however, have received less attention despite their prevalent use for backlighting, general lighting and architectural purposes. Currently, Environmental Product Declarations (EPDs) of lighting devices and electronic devices with backlit screens do not address endpoint impacts nor do they specify technical properties of the light that can enable such an assessment. This study investigates endpoint impacts of eleven lighting devices (1) due to light exposure during the use phase and (2) due to emissions throughout their life cycle. Impacts are quantified as disease burden in terms of disability adjusted life years (DALY). The burden of exposure was calculated using attributable fraction (AF) method. The burden due to life cycle emissions was quantified using GaBi software and built-in life cycle impact assessment (LCIA) method ReCiPe. Endpoint impact categories included were climate change human health, human toxicity, ionizing radiation, ozone depletion, particulate matter formation, and photochemical oxidant formation. The disease burden due to light exposure of all light sources is of two orders of magnitude greater than the disease burden due to life cycle emissions pointing to the need for its treatment.     

区域生态风险评价的关键问题与展望

区域生态风险评价具有多风险因子、多风险受体、多评价终点、强调不确定性因素以及空间异质性的特点,它与传统的生态风险评价在风险源、胁迫因子和评价尺度上具有明显区别。尝试建立了一个基于陆地生态系统的区域生态风险评价框架,同时针对目前区域生态风险评价的研究现状,指出不确定性分析、尺度外推难、评价指标不统一、评价标准不统一、风险因子筛选及优先排序、区域内污染物复合、水生过渡到陆生生态系统风险评价、特殊的人为因素等是目前区域生态风险评价存在的关键问题及难点所在,并提出解决这些问题可能所需的工具、手段和理论方法突破。最后指出区域生态风险观测与数据采集加工、区域生态风险指标体系的统一与整合、区域生态风险评价方法论、区域生态风险的空间分布特征与表达以及区域生态风险评价反馈与管理机制5个方面是区域生态风险评价未来的研究重点。     

Perspectives on environmental risk assessment

Risk is by no means a simple concept. Natural variability and definitional problems with the concept of probability complicate the measurement and use of risk as an analytical tool. Variability requires that risk assessment methods separate natural from total risk when attempting to estimate anthropogenic risk. Failure to do so results in the over estimation of anthropogenic risk and the eventual loss of credibility for risk assessment methodologies. The common frequentist approach to probability is not consistent with anything but a modelling approach to risk assessment. When combined with its ability to account for natural variability, incorporate laboratory-assay data and offer complete statistical and experimental control, modelling is a promising approach to risk assessment. Modelling, however, is not without its drawbacks. Initialization bias can result in the over, or under, estimation of both natural and anthropogenic risk. Furthermore, model estimates are time dependent. The convergence of natural and anthropogenic risk poses problems for modelling-based risk assessment and requires clear statements as to the importance of the time dimension in risk assessment. When combined, the drawbacks to modelling-based risk assessment argue that risk should never be stated as a scalar quantity. Instead, modelling-based risk assessment should provide estimates of the complete range of risk measures (total, natural, and anthropogenic) as well as indications of convergence time. Only then can the modelling-based approach be viewed as the most appropriate means of carrying out scientifically credible risk assessment.     

Biomarkers in risk assessment of asbestos exposure

Developments in the field of molecular epidemiology and toxicology have given valuable tools for early detection of impending disease or toxic condition. Morbidity due to respiratory distress, which may be due to environmental and occupational exposure, has drawn attention of researchers worldwide. Among the occupational exposure to respiratory distress factors, fibers and particles have been found to be main culprits in causing diseases like asbestosis, pleural plaques, mesotheliomas and bronchogenic carcinomas. An early detection of the magnitude of exposure or its’ effect using molecular end points is of growing importance. The early inflammatory responses like release of the inflammatory cells collected by non-invasive methods give an indication of the unwanted exposure and susceptibility to further complications. Since free radicals like O₂⁻, OH, OOH, NO, NOO, etc. are involved in the progression of asbestos-related diseases and lead to cytogenetic changes, an evaluation of antioxidant states reducing equivalents like GSH and ROS generation can be a good biomarker. The cytogenetic end points like chromosomal aberration, micronucleus formation and sister chromatid exchange give indication of genetic damage, hence they are used as effective biomarkers. New techniques like fluorimetric analysis of DNA unwinding, alkaline elution test, fluorescent in situ hybridization and comet assay are powerful tools for early detection of initiation of disease process and may help in planning strategies for minimizing morbidity related to asbestos fiber exposure. The present review article covers in detail possible biomarkers for risk assessment of morbidity due to fibers/particles in exposed population.