Individual Carcinogenic Risks Research Articles

Risks assessment to the health of the population in the area of emissions pollutants influence of carbon graphite production enterprises

Risk assessment of the impact of the enterprise's activities on the environment includes risk assessment of the impact of the activity on the health of the population. Risk as the probability of undesirable events is an integral component of any person's life. Risk characterization integrates data on the danger of the analyzed chemical substances, the amount of exposure, parameters of "dose-response" dependence, with the aim of quantitative and qualitative assessment of risk, identification and assessment of the comparative significance of existing problems for the health of the population. In scientific terms, hazard identification is the process of establishing a causal relationship between the action of a chemical substance and the development of adverse effects on human health. The main goal of the hazard identification stage is the selection of priority, indicator chemical substances, the study of which allows to reliably characterize the sources of occurrence and the level of risk of public health impairment. Assessment of dose-response relationships is a process of quantitative characterization of toxicological information and establishment of a relationship between the likely influencing dose (concentration) of a pollutant and the incidence of adverse events in the exposed population. Characteristics of "dose-response" dependence, which are most often used to assess carcinogenic risk, have been sufficiently studied in epidemiological studies. Among them is the factor of carcinogenic potential (ICS), which reflects the probability of the development of a harmful reaction when the dose (concentration) increases by 1 mg/kg or 1 mg/m3 per exposure level, associated with a certain probability of effect (the indicators of this group are used for establishment of reference, i.e., reference doses and concentrations). The individual carcinogenic risk characterizes the upper limit of possible carcinogenic risk during the period corresponding to the average life expectancy of a person (70 years). Today, in the world, the classification and assessment of the acceptable risk to the health of the population caused by the chemical influence of chemical substances that pollute the environment is quite wide. the system of acceptance criteria recommended by WHO is used. In accordance with these criteria, the first range of risk (individual lifetime risk equal to or less than 1·10-6, which also corresponds to an additional case of serious illness or death per 1 million exposed persons) characterizes such levels of risk as are perceived by all strata population as quite small, which do not differ from ordinary everyday risks (De minimas level). Such risks do not require additional measures to reduce them and their levels are subject to periodic control. The second range (greater than 1·10-6 and less than 1·10-4) corresponds to the zone of conditionally accepted (acceptable) risk. It is at this level that most of the foreign and recommended by international organizations hygienic standards for the population as a whole are established. Levels of suitable risk belong to constant control. The third range (greater than 1·10-4 and less than 1·10-3) is suitable for professionals and unsuitable for the general population. The emergence of such a level of risk requires the development and implementation of planned health measures. The fourth range (equal to or greater than 1·10-3) is unsuitable neither for the population nor for professionals. This range is designated as De manifestis Risk, and when it is reached, it is necessary to carry out emergency health measures to reduce the risk on the part of the city authorities. During the assessment of the risk to the health of the population of Zaporizhzhia from the emissions of PJSC "Ukrgrafit", priority pollutants were identified: carbon oxides, nitrogen oxides, sulfur oxides, substances in the form of suspended solid particles of undifferentiated composition. Hazard indices were determined for individual HQ substances (non-carcinogenic risks) and in the case of combined exposure to HI, individual carcinogenic risks (ICR) and combined exposure (CRa) were calculated. Assessment of long-term effects (at the level of average annual concentration) on human health of the investigated substances. allowing to assess the chronic inhalation effect of the occurrence of negative effects in the health of the exposed population during the lifetime for the assessment and characterization of multistage risk showed that the hazard indices (HQ) do not exceed the norms.

Carcinogenic risk associated with atmospheric air pollution in industrial cities of the Central Chernozem region

Introduction. Industrial cities are characterized by a significant amount of emissions of carcinogenic substances into the atmospheric air. In this regard, for the development of preventive measures, there is needed research to quantify the carcinogenic risk to health.
 The aim of the work was to quantify the carcinogenic risk associated with aerotechnogenic pollution of the cities of the Central Chernozem region including Voronezh, Lipetsk, and Belgorod.
 Materials and methods. Data on the results of monitoring laboratory studies in 2017–2022 were used as initial data. The carcinogenic risk was assessed according to G. 2.1.10.1920–04 “Guidelines for assessing the risk to public health when exposed to chemicals that pollute the environment”.
 Results. Taking into account the available objective data of laboratory control of carcinogens in the atmospheric air of the cities of the Central Chernozem region of Russia, pollutants have been identified whose exposure under standard exposure scenarios causes the level of individual carcinogenic risk to public health above the maximum permissible (1 • 10–4): in Voronezh – 1,3–butadiene (the source of emissions is the production of synthetic rubber) and chromium6+ compounds (the main source of emissions is an aviation plant); in Lipetsk – formaldehyde, at some control points – benzene (the main sources are emissions from metallurgical production and motor transport). Attention should be paid to the need to improve monitoring of the content of carcinogens in the atmospheric air of Belgorod, because in the presence of many sources of pollution, the concentrations of only two carcinogens are controlled.
 Limitations. The limitations of the study are due to the fact that the calculation of individual carcinogenic risks is always inherent in the uncertainties associated with the assessment of exposure and the use of standard formulas for calculating doses of intake into the body.
 Conclusion. To reduce the carcinogenic risk associated with air pollution, a set of measures should be implemented to reduce the intake of carcinogenic pollutants into the atmospheric air, and to implement rational urban planning decisions.

Health risk assessment of volatile organic compounds (VOCs) emitted from landfill working surface via dispersion simulation enhanced by probability analysis

The assessment of the health risks of volatile organic compounds (VOCs) emitted from landfills via dispersion model is crucial but also challenging because of remarkable variations in their emissions and meteorological conditions. This study used a probabilistic approach for the assessment of the health risks of typical VOCs by combining artificial neural network models for emission rates and a numerical dispersion model enhanced by probability analysis. A total of 8753 rounds of simulation were performed with distributions of waste compositions and the valid hourly meteorological conditions for 1 year. The concentration distributions and ranges of the typical health-risky VOCs after dispersion were analyzed with 95% probability. The individual and cumulative non-carcinogenic risks of the typical VOCs were acceptable with all values less than 1 in the whole study domain. For individual carcinogenic risks, only ethylbenzene, benzene, chloroform, and 1, 2-dichloroethane at extreme concentrations showed minor or moderate risks with a probability of 0.1%–1% and an impact distance of 650–3000 m at specific directions. The cumulative carcinogenic risks were also acceptable at 95% probability in the whole study domain, but exceeded 1 × 10−6 or even 1 × 10−4 at some extreme conditions, especially within the landfill area. The vertical patterns of the health risks with height initially increased, and then decreased rapidly, and the peak values were observed around the height of the emission source. The dispersion simulation and health risk assessment of the typical health-risky VOCs enhanced by Monte Carlo can accurately reflect their probabilistic dispersion patterns and health risks to surrounding residents from both spatial and temporal dimensions. With this approach, this study can provide important scientific basis and technical support for the health risk assessment and management of landfills.

Оценка вклада онкогенных факторов в риск развития злокачественных новообразований у городского населения трудоспособного возраста

High morbidity and mortality caused by malignant neoplasms in various age groups among urban population remains a pressing issue that public healthcare has to solve in contemporary megacities. This research concentrated on assessing significance of oncogenic risk factors that could cause malignant neoplasms (MNs) occurrence among urban population aged 18–64 inclusively. 766 people living in an administrative and industrial center in Siberia took part in the research; MNs were diagnosed in 367 out of them (the test group). The research involved calculating individual carcinogenic risks. Oncogenic factors, both environmental and occupational ones, were examined for each patient; attention was also paid to peculiarities of medical and biological characteristics as well as tobacco smoking and alcohol intake. Impacts exerted by the examined factors on risks of MNs occurrence were determined via odds ratios with estimated confidence intervals. First detected MNs frequency amounted to 638.9 ± 41.9 cases per 100 thousand people among women aged 18–64, and 532.6 ± 41.9 cases among men (p > 0.05). The following factors were determined as ones causing elevated risks of MNs occur- rence: carcinogenic hazards at a workplace; hereditary predisposition; tobacco smoking; alcohol abuse; female sex; living under exposure to chemical carcinogens in the environment. Women tended to have certain diseases that are conventionally considered possible risk factors (viral hepatitis B and C and pancreatic diabetes) 1.3 and 2.4 times more frequently than men. All the obtained data can be used for developing a targeted program aimed at malignant neoplasms prevention among urban population and they can also become a vital component in a system for managing risks of malignant neoplasms occur- rence on a given territory.

ASSESSMENT OF THE CONTRIBUTION MADE BY ONCOGENIC FACTORS TO THE RISK OF MALIGNANT NEOPLASMS DEVELOPMENT FOR THE URBAN POPULATION OF WORKING AGE

High morbidity and mortality caused by malignant neoplasms in various age groups among urban population remains a pressing issue that public healthcare has to solve in contemporary megacities. This research concentrated on assessing significance of oncogenic risk factors that could cause malignant neoplasms (MNs) occurrence among urban population aged 18–64 inclusively. 766 people living in an administrative and industrial center in Siberia took part in the research; MNs were diagnosed in 367 out of them (the test group). The research involved calculating individual carcinogenic risks. Oncogenic factors, both environmental and occupational ones, were examined for each patient; attention was also paid to peculiarities of medical and biological characteristics as well as tobacco smoking and alcohol intake. Impacts exerted by the examined factors on risks of MNs occurrence were determined via odds ratios with estimated confidence intervals. First detected MNs frequency amounted to 638.9 ± 41.9 cases per 100 thousand people among women aged 18–64, and 532.6 ± 41.9 cases among men (p > 0.05). The following factors were determined as ones causing elevated risks of MNs occur- rence: carcinogenic hazards at a workplace; hereditary predisposition; tobacco smoking; alcohol abuse; female sex; living under exposure to chemical carcinogens in the environment. Women tended to have certain diseases that are conventionally considered possible risk factors (viral hepatitis B and C and pancreatic diabetes) 1.3 and 2.4 times more frequently than men. All the obtained data can be used for developing a targeted program aimed at malignant neoplasms prevention among urban population and they can also become a vital component in a system for managing risks of malignant neoplasms occur- rence on a given territory.

Обґрунтування регіональної програми моніторингу за якістю атмосферного повітря у Дніпропетровській області

The air quality monitoring system in industrial cities is one of the systems for responding to risk factors in the public health system. The purpose of the study is, on the basis of a hygienic assessment of carcinogenic and non-carcinogenic risks from exposure to specific pollutants in the cities of Dnipro, Kamenskoye, Kryvyi Rih, to substantiate a program for regional monitoring of atmospheric air quality. Materials and methods. To achieve this goal, the results of air quality studies in the largest industrial cities of the Dnipropetrovsk region – Dnipro, Kryvyi Rih and Kamenskoe for the period 2005-2019 were analyzed in terms of phenol, formaldehyde, benzene, xylene and toluene, and carcinogenic and non-carcinogenic risks to public health were calculated in these cities. Results and discussion. According to the results of the study, individual carcinogenic risks in all three cities in terms of formaldehyde are medium, and in terms of benzene are high. The population carcinogenic risk ranges from 200-269 additional cases of cancer from exposure to formaldehyde and 3727-4426 additional cases of cancer from chronic inhalation exposure to benzene. The calculation of non-carcinogenic risks identified the priority specific air pollutants in the cities under study, as well as the main target organs. So the main systems that are influenced by the action of the studied chemicals are the central nervous system, the general development of the body and the blood system. Based on the risk assessment, it was established that it is necessary to include the Kamenskoye metro station for regional monitoring. It is necessary to include all pollutants from List A to the minimum list of investigated chemicals, and for the city of Dnipro and Kamenskoye it is additionally necessary to carry out studies of phenol, formaldehyde and toluene and in the city of Kryvyi Rih – formaldehyde and toluene. The mechanism of data processing and interaction between the subjects of monitoring has been substantiated for the timely identification of risks and the development of necessary preventive measures for risk management. Conclusion. It was found that carcinogenic and non-carcinogenic risks in industrial cities of the Dnipropetrovsk region are not acceptable. The existing monitoring system does not fully comply with the current requirements. The minimum program of the regional air quality monitoring system in the Dnipropetrovsk region has been scientifically substantiated

Changes in the indicators of chemical safety of drinking water in Ufa during its transportation to consumers

Introduction. To conduct a total assessment of carcinogenic, non-carcinogenic, and organoleptic risks to public health and cover both normalized and non-normalized pollutants of potable water, based on the results of long-term monitoring studies, it is possible using an integral indicator of chemical harmlessness of water. Material and methods. Authors studied potable water of water intakes of surface and infiltration types from potable water reservoirs and remote zones of Ufa water distribution networks. Impurities were determined by chromatography, inductively coupled plasma mass spectrometry, photometric, nephelometric, and titrimetric methods. Results. The main effect on the amount of carcinogenic risk in potable water of the surface water intake are chloroform, bromodichlethane, dichloroacetic acid, in the infiltration water intake - in addition to these compounds zinc, lead and chromium are in addition influenced. Organic compounds (phthalates, benz(a)pyrene, volatile aromatic compounds, etc.) have no effect on this type of risk due to the presence in water in low background concentrations. The identified number of individual carcinogenic risks for bromodichloroacetic acid and dichloroacetic acid according to the WHO classification corresponds to the second range. As the surface type water intake is removed from the potable water reservoir, the total carcinogenic risk of water decreases by 13-30%, and the infiltration type increases by 41-84%. Values of noncancerogenic and organoleptic risks are constant for potable water of different water intakes and correspond to recommended limit values. The excess of the maximum permissible concentrations (SanPin 1.2.3685-21) of individual substances in the potable water of the city has not been detected for the whole period of observation. In terms of the integral indicator of chemical harmlessness, the most favorable is the po-table water of the infiltration water intake, in the technology of which is mainly used the UV for decontamination of water. Conclusion. Using a risk assessment methodology complements the traditional approach to assessing water quality under modern hygiene standards. It becomes possible to evaluate the effect of pollutants of various classes on water quality when they are present together.

Approaches to Regulating Organic Carbon and the Necessity of Its Obligatory Monitoring in Drinking Water

Background: Current accumulation of organogenic elements in surface waters is mainly attributed to intensive anthropogenic activities. Waterborne organic matter may endanger human health when using surface waters for drinking and recreational purposes. Applied techniques of water treatment fail to ensure complete water purification and part of organic substances (their low molecular weight fraction) still remains. Chlorination of drinking water can generate a variety of halogenated by-products having adverse health effects in humans including carcinogenic ones. Our objective was to substantiate the reference value for total organic carbon (TOC) in water disinfected by chlorine. Materials and methods: We analyzed the results of laboratory testing of surface and treated water samples taken in Yekaterinburg in 2013–2014 and 2017, carried out health risk assessment, and built predicative models of by-products formation. Results: We established that, following chlorination, TOC concentrations became 1.5 times lower while chloroform and total trihalomethane concentrations became 24.5–80.2 and 22.9–54.5 times higher than initial values, respectively. The most significant non-carcinogenic risks were estimated for children aged 0-6 years from exposures to chloroform (HQ = 1.150). Individual carcinogenic risks from exposures to bromoform and dibromochloromethane as measured in water before its supplying to the distribution system, referred to the first value range (less than 1×10–6) while risks from bromodichloromethane and chloroform exposures fell in the second range (from 1×10–6 to 1×10–4). The mathematical model of the correlation between predictors (temperature, reaction time, pH, and certain chemical compounds) and levels of by-products was built. Conclusions: Our model makes it possible to predict generation of organochlorine compounds at the design stage of water treatment technique. Total organic carbon is an important indicator that should be monitored at the stages of water treatment to ensure safety of drinking water and efficiency of its disinfection.

ASSESSMENT OF CARCINOGENIC RISK TO PUBLIC HEALTH WHEN USING GROUNDWATER WITH HIGH ARSENIC CONTENT AS SOURCES OF DRINKING WATER SUPPLY ON THE EXAMPLE OF THE REPUBLIC OF DAGESTAN

Hygienic assessment of drinking groundwater used for drinking water supply by the population of the Northern part of the Republic of Dagestan for several decades has been carried out. The content of arsenic in drinking water sources was found to be up to 50 times higher than the permissible WHO standard. The use of regional factors of water consumption allowed to calculate individual and population carcinogenic risks to the population during long-term use of groundwater for drinking water supply. It was shown that the individual carcinogenic risk was 4,3E-4 at the minimum concentration of 0,01 mg/L; 2,1E-2 at the maximum concentration of 0,5 mg/L, and 6,0E-3 at the average value of 0,14 mg/L, respectively. The identified levels of lifetime individual carcinogenic risks (over 70 years) exceed the «acceptable» (target) level of 10 -5 and are assessed as unacceptable for the preservation of public health. For the exposed population of the studied regions of Northern Dagestan (309,7 thousand) the values of population annual carcinogenic risks, reflecting the additional (to the background) number of cases of malignant neoplasms that can occur during the year, ranged from 1 to 95 cases. The results of this study allowed to identify areas with high levels of arsenic in drinking water and to identify the exposed part of the population for the implementation of measures to reduce the risk. To assess the population’s exposure and establish a link between exposure to arsenic and its accumulation in humans, the biomonitoring has been conducted, the results of which allowed to identify the correlation between arsenic content in hair of residents and it’s exhibited content in consumed drinking water.

Reduction of individual carcinogenic and non-carcinogenic risks on impact area resulted from operation of construction industry enterprises

The article presents the assessment of carcinogenic and non-carcinogenic risks to the human health resulted from the work of the construction industry enterprises. It is shown that the level of risks to the human health causes concern. It is established that while assessing carcinogenic and non-carcinogenic risks to the human health the construction enterprises don’t take into account the emission of mercury compounds in cement production. Both the sources of mercury emission into the atmosphere and the methods for reducing mercury emission in cement production technique are shown. It’s stated that to improve the environment, it is necessary to define impact areas, provide a sanitary protective barrier between the industrial territory and the residential area by creating additional green belts that provide shielding, assimilation and filtration of air pollutants which make the microclimate better. It is suggested that monitoring of atmospheric emission of mercury should be included in the production control program and pollution control for mercury emissions should be introduced into Maximum Permissible Emissions (MPEs) projects.

RELATIONSHIP BETWEEN MAXIMUM PERMISSIBLE CONCENTRATIONS AND LEVEL OF HEALTH RISK FOR AIR POLLUTANTS

There was executed the complex assessment of air pollution in the city Novokuibyshevsk in 2014. There were outlined basic chemicals exceeding hygienic standards, as well as causing both carcinogenic and non-carcinogenic health risk. Average concentrations of pollutants were shown to fail to exceed the average daily maximum permissible concentration, and on the basis of this air pollution index in the city of Novokuibyshevsk was the low in 2014. However, air pollution in the city of Novokuibyshevsk decreased not due to the reduction of the concentration of priority pollutants, but as a result of the revision of the admissible values for formaldehyde concentrations. Individual carcinogenic risks to the health of children under 18 years according to hexavalent chromium, benzene and formaldehyde exceeded the border of maximum permissible risk, and were attributed to the third reference range of risk values in accordance with the R 2.1.10.1920-04. The carcinogenic risk to the health of adults and the population of the city of Novokuibyshevsk as a whole was in the third reference range boundaries only for hexavalent chromium. However, the overall carcinogenic risk for health of children aged up to 18 years amounted to 1.18∙10-3 and moved into a fourth reference range boundaries. The total index of danger with all substances, the content of which was monitored in the ambient air in the city of Novokuibyshevsk, accounted for 17.74 and also demanded measures to reduce air pollution in the near future.

ASSESSMENT OF RISKS TO THE HEALTH OF THE POPULATION FROM AIR BORNE CONTAMINANTS IN CERTAIN AREAS OF MOSCOW (BASED ON THE FINDINGS OF ON-GOING SOCIO-HYGIENIC MONITORING)

There was executed the assessment of carcinogen and non-carcinogen risks for population health in some areas of the western, south-western and south-eastern administrative districts of Moscow under the exposure to air borne contaminants whose levels are kept track by various government agencies as part of the socio-hygienic monitoring. The value of chronic non-carcinogenic risks to the health of the population as measured according to the danger index for the combined impact of average annual concentrations of leading air borne contaminants with unidirectional impacts are at near alarming or high level depending on the location of monitoring outposts while for on-off short term exposure to maximum concentrations the impacts are at alarming or acceptable level. The highest danger indices were detected at outposts located near major motorways and industrial facilities. According to monitoring data collected by all agencies the air borne contaminants pose the highest risk to the respiratory organs due to exposure to formaldehyde, air-borne particles and nitrogen dioxide. The extra deaths resulting from chronic exposure to РМ10, estimated by the Moscow Environmental Monitoring make up about 1% of the total mortality rate without bearing in mind of external causes for the population residing in the western, south western and south eastern administrative districts. The total individual carcinogenic risks resulting from the exposure to average annual concentration of a number of carcinogens was found to be between the acceptable and alarming levels. The leading compound contributing to the increased carcinogenic risk is formaldehyde.

INFLUENCE OF PROOXIDANT NATURE ON EVOLUTION OF FORMALDEHYDE FROM OXO-DEGRADABLE POLYETHYLENE

In the article, methods of oxo-destruction of polyethylene modified with pro-oxidants of various nature are considered taking into account ecotoxicological aspects. A comparative evaluation of the indexes of degradation of polyethylene under the influence of air oxygen under accelerated thermal aging and under natural conditions is presented. It was revealed that the degradation index rises in the series "iron <copper <cobalt". The amount of formaldehyde in the gas-air extraction of oxo-degradable polyethylene modified with iron, cobalt and copper stearate is determined with accelerated thermal-oxidative degradation. The degree of isolation of formaldehyde increases in the series "copper <iron <cobalt", which indicates different periods of induction of the degradation process initiated by prooxidates, as well as the presence of side processes that affect the depth of destructive processes. It has been established that a polyethylene film modified with cobalt stearate contributes to the increase in formaldehyde emissions, while the formaldehyde content in the gas phase is 0.065 mg / m3 (per 1 g of sample), which exceeds MAC m.o.t by 1.3 times. The content of formaldehyde precipitates in the gas phase is reduced by 3.25 times, with the use of ferrous sterate. Individual carcinogenic risks (ICR) for oxo-degradable films based on iron, copper and cobalt stearates are predicted to equal 6.593·10-5, 5.595·10-5 2.864·10-4, respectively. A comparative analysis of prooxidants allows us to conclude that the use of iron and copper stearates contributes to a slower degradation of polyethylene and reduces its ecotoxicological hazard, the use of cobalt based pro-oxidants contributes to a faster and deeper destruction, but is accompanied by increased release of formaldehyde in the oxodegradation of modified polyethylene. Of interest is the further study of complex prooxidants on the basis of iron with trace amounts of cobalt as highly effective and environmentally friendly modifiers of polyolefins, contributing to their accelerated oxidation in the environment, as well as the development of technical solutions to reduce the risk in the case of cobalt stearate as an effective prooxidant.

ESTIMATION AND RISK MANAGEMENT IN THE WASTE TREATMENT

In modern conditions, there are unacceptable risks of harm from exposure to hazardous chemical and biological factors for public health and the environment. The complexity and scale of environmental and hygiene problems that directly or indirectly affect the state of the nation’s health require active action on priority strategically important areas. One, of which is the waste management system, which can cope with the growing volumes and species diversity of waste. The components of the public health risk caused by the formation, accumulation, recycling, and disposal of wastes are the factors of the negative complex impact on the environment during inter-environment migration of pollutants. Solid municipal waste landfills are sources of long-term negative environmental impact due to the receipt of a highly toxic filtrate and biogas containing greenhouse gases and toxic substances. The aim of the study was to investigate the effect of chemicals entering the atmospheric air from polygons with an assessment of the health risks. Studies have been conducted for a landfill located near and serving the largest urbanized area in the region. The methodology of risk assessment in accordance with R.2.1.10.1920-04 “Guidelines for the assessment of risk to public health in the impact of chemicals polluting the environment” has been applied. In the course of the study, a list of chemicals entering the atmospheric air during the life cycle and production activities of the landfill was determined based on the evaluation and analytical method. The risk assessment methodology applied in the waste management system allowed calculating of individual carcinogenic and non-carcinogenic risks, as well as hazard indices when exposed to critical organs and systems and to develop further tactics for conducting monitoring in the areas in the zone affected by the test site.

Evaluation of Incremental Population and Individual Carcinogenic Risks of PCDD/Fs from Steel and Iron Industry in Taiwan by a Site-specific Health Risk Assessment Method

Sinter plants and electric arc furnaces are the most important emission sources of PCDD/Fs. In order to understand the contribution and distribution of PCDD/Fs risk from steel and iron industry, the incremental health risk assessment of PCDD/Fs has been accomplished for the all sinter plants and electric arc furnaces in Taiwan. The study combined the multimedia, multiple pathway exposure modeling and site-specific exposure scenario to evaluate dioxin risks contributed from the 22 major companies of steel and iron industry including 4 sinter plants and 21 electric arc furnaces. The incremental cancer risks to the resident living in the 25 km × 25 km impact range of the above emission sources ranged from 3.10E-10 to 5.73E-06 under the site-specific exposure scenario. Among these 22 emission sources, the stacks with higher exit flows and worse operational characteristics would contribute higher inhalation risks; moreover, the sources located at the major agricultural districts in central Taiwan contributed higher ingestion risks. In conclusion, four sinter plants accounted for more than 24% of total PCDD/Fs exit rates in steel and iron industry, and the incremental risks of these were lower than those of other electric arc furnaces investigated in this study. Furthermore, comparing background cancer mortality for incremental PCDD/Fs risks of steel and iron industry, the total PCDD/Fs population risks contributed from steel and iron industry are low but still cannot be ignored.

Doses to critical organs following radiotherapy and concomitant imaging of the larynx and breast

The development of conformal radiotherapy carries with it the implication of an increased number of imaging procedures at various stages throughout the overall treatment, principally for verification at some, or all, of the treatment fractions. This raises the issue of the balance between the benefit of these additional imaging exposures and the associated risk of radiocarcinogenesis arising from them. As such, it is necessary to appreciate the doses to critical organs for which individual carcinogenic risks have been estimated. In this study, doses to these organs have been measured with lithium fluoride thermoluminescence dosimetry loaded in anthropomorphic phantoms and subjected to realistic radiotherapy treatments of the larynx and breast, including concomitant CT and electronic portal imaging exposures associated with localization and verification of these treatments. Even for large numbers of concomitant images of either modality, arising from imaging at every fraction, the leakage and scatter from the radiotherapy itself is shown to dominate the overall organ dose, with imaging procedures generally contributing 5-20% of the total organ dose.

Influence of the prooxidant nature on the evolution of formaldehyde from oxo-degradable polyethylene

In the article methods of oxo-destruction of polyethylene modified with pro-oxidants of various nature are considered, taking into account ecotoxicological aspects. A comparative evaluation of the indices of degradation of polyethylene under the influence of air oxygen under accelerated thermal aging and under natural conditions is presented. It was revealed that the degradation index rises in the series "iron <copper <cobalt". The amount of formaldehyde in the gas-air extraction of oxo-degradable polyethylene modified with iron, cobalt and copper stearate is determined with accelerated thermal-oxidative degradation. The degree of isolation of formaldehyde increases in the series "copper <iron <cobalt", which indicates different periods of induction of the degradation process initiated by prooxidates, as well as the presence of side processes that affect the depth of destructive processes. It has been established that a polyethylene film modified with cobalt stearate contributes to the increase in formaldehyde emissions, while the formaldehyde content in the gas phase is 0,065 mg / m3 (per 1 g of sample), which exceeds MAC m.o.t by 1.3 times. The content of formaldehyde precipitates in the gas phase is reduced by 3.25 times, with the use of ferrous sterate. Individual carcinogenic risks (ICR) for oxo-degradable films based on iron, copper and cobalt stearates are predicted to equal 6.593·10-5, 5.595·10-5 2.864·10-4, respectively. A comparative analysis of prooxidants allows us to conclude that the use of iron and copper stearates contributes to a slower degradation of polyethylene and reduces its ecotoxicological hazard, the use of cobalt based pro-oxidants contributes to a faster and deeper destruction, but is accompanied by increased release of formaldehyde in the oxodegradation of modified polyethylene. Iron-based prooxidants with trace amounts of cobalt as in highly effective and ecofriendly modifiers of polyolefins that promote their accelerated oxodegradation in the environment, as well as further development of technical solutions to reduce the risk of using cobalt stearate as an effective prooxidant.