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Radiochemical indoor environment and possible health risks in current building technology
Building and Environment 46 (2011) 2609e2614
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Building and Environment journal homepage: www.elsevier.com/locate/buildenv
Radiochemical indoor environment and possible health risks in current building technology Aleksandra Fucic a, *, Lino Fucic b, Jelena Katic a, Ranko Stojkovi c c, Marija Gamulin d, Enes Seferovi ce a
Institute for Medical Research and Occupational Health, Ksaverska c 2, 10 000 Zagreb, Croatia Ministry of Environmental Protection, Physical Planning and Construction, Zagreb, Croatia c Institute “Rudjer Boskovic”, Zagreb, Croatia d Zagreb University Hospital, Zagreb, Croatia e CSS Ltd, Zagreb, Savska c 144a, Croatia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 29 April 2011 Received in revised form 14 June 2011 Accepted 16 June 2011
Tremendous work of civil and environmental engineering has been focused on development of sustainable buildings. From economical and ecological viewpoint, this approach is a significant step forward, but the microenvironment created in such living surroundings may present a complex radiochemical setting, which could be a threat to the health of its occupants. This paper gives overview about levels of indoor radon, insight in risks related with radioactivity of fly ash and zircon, current application of nanoparticles and concrete additives in buildings and their possible impact on human health. As construction engineering is current producer of almost 50% of waste encouragement of incorporation of toxic and radioactive agents in buildings could in future demand redefinition of building construction waste as hazardous and special waste disposals. Collaboration between governmental and nongovernmental bodies, manufacturers, scientific institutions, and chartered engineers is needed in order to find balance between quality of indoor air, and to enable maintaining of high health standards by application of non-toxic or non-carcinogenic building materials that meet energy efficiency, building structure stability and security requirements. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Indoor radon Fly ash Radionuclides Nanoparticles Human health Concrete additive
1. Introduction Construction products and materials as well as building technologies used currently in developed construction economies create complex radiochemical microenvironmental living settings. Outdoor air pollution in epidemiological studies has clearly been demonstrated as a health risk factor [1], but it has been recognized that indoor air quality may have a greater contribution to overall public health [2e4]. Considering that modern lifestyle involves spending most of the time (70e80%) indoors [5], ambient air quality becomes even more significant. Dangerous gases, particles and fibres which are continuously being emitted at room temperature from some building and furnishing materials affect indoor air quality. In addition to indoor radon lifelong exposure, some construction products containing radionuclide can increase indoor exposure to ionizing radiation.
* Corresponding author. Tel.: þ385 14682521; fax: þ385 4673303. E-mail address: [email protected] (A. Fucic). 0360-1323/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2011.06.020
Significant efforts of civil and environmental engineering are focused on development of sustainable buildings. Real estate market demands built environment that meets high visual and aesthetic standards, as well as acceptable noise and energy consumption level by what request application of new construction products. Sophisticated isolating materials and constructions meet public and industry demands regarding noise and cooling/heating energy consumption. Through this process, these so-called selfsufficient homes have become “air-tight” and isolated from interaction with the outer environment more than ever before. From economical and ecological viewpoint this is a significant step forward, but indoor air quality in such closed systems relies on ventilation, type of the heating/cooling system, natural background radiation, and on components of construction products which may emit xenobiotics into the living environment, causing different health problems. Other lifestyle activities and habits in homes, such as use of household products, open fire, and environmental tobacco smoke could also elevate the concentrations of hazardous agents in indoor environment. Over the last 50 years, levels of chemicals suspected as endocrine disruptors have significantly increased in indoor environment, but also in the blood and urine of occupants [6], yet little is known about the monitoring of such indoor
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exposure in everyday life. This is especially significant for early life exposure to indoor pollutants, which could impair the development of the infant immune system and increase the risk of respiratory diseases in children [7]. The aim of present study is to give an insight into indoor microenvironment created by currently used construction products and building technologies which are common in developed construction economies. Indoor radon, fly ash, nanoparticles, zircon, and concrete additives are selected building materials in regard to their impact on human health and prevalence in types of exposures. Volatile organic compounds (VOCs) emission from finishing coatings and furnishing of buildings are not included, but only discussed in relation with construction products. The results of our study may be applied in future as a basic platform for interdisciplinary panel which may provide optimal improvement of building practice from economical, structural, noise, energy saving, and health quality points. 2. Indoor radon Radon is a radioactive gas which naturally occurs in soil and rocks. By entering buildings through cracks in the construction it becomes an indoor phenomenon. In soils which contain high concentrations of radon, indoor exposure is in correlation with increased risk of lung cancer, with an excess relative risk of 10% per 100 Bq m3 [8]. In healthy population it is also possible to measure health risk by estimating genome damage level caused by radiation emitted from radon. Thus, a significant increase in genome damage was shown in children who spent up to 5 h per day in classrooms with radon levels in the range of 900e3200 Bq m3 [9]. Interindividual differences in radiosensitivity to radon have been described in Caucasians who are carriers of gluthatione-S-transferase null genotype, which presence is associated with a three times higher risk of lung cancer after exposure to levels higher than 121 Bq m3 [10]. A synergism between smoking and radon in lung cancer aetiology has been described in several studies, which have also shown an impact of human behaviour on the quality of indoor environment [11e13]. An example of good practice in mitigating indoor radon exposure can be seen in the United Kingdom, where the soil in some areas is responsible of very high indoor radon levels. In 1990, the UK government accepted the National Radiological Protection Board’s (NRPB) advice that remedial measures should be taken in homes with radon levels above the Radon Action Level, which is 200 Bq m3. At the same time, Radon Affected Areas were defined as areas of the country where 1% or more of properties were estimated to be equal to or higher of the Radon Action Level. This programme was based on a publicly financed radon measurement program. The United Kingdom implemented a prevention programme coordinated by the UK Health Protection Agency (HPA), the British Geological Survey (BGS) and Building Research Establishment (BRE), which also prepared new and more detailed maps of radon-affected areas. On the global level, in 2009, the World Health Organization [14] issued a recommendation according to which the Action Level for radon in homes should be reduced to 100 Bq m3. In the European countries where 0.5%e15% of houses have radon concentrations above 200 Bq m3, remedial measures are needed [15]. The key messages of the World Health Organization International Radon project relevant for the construction sector are that: (a) strategies both for radon prevention in new dwellings and mitigationin existing dwellings are needed to achieve an overall risk reduction; (b) professionals in the construction sector are the key players for radon prevention and mitigation; therefore strategies are needed to train them and to ensure their competence in this area; and (c)
research-based guidelines and/or standards for radon prevention and mitigation should be established at the national level. In the same report comparison of different control systems and costeffectiveness are presented in details. One of the important conclusions of this report is that even when cost-effectiveness analysis is not justified on the national level, high levels of radon may be considered as a lung cancer risk on individual bases and remediation should be performed. Although radon mapping in Europe is in progress, it has not been yet started in a number of countries, and this is probably the reason for which the process of preparing regulation or directive on the European level is running slow. The cost-effectiveness of future policies is confirmed, especially if complemented with policies for smoking reduction [16]. Specific provisions in regulations for radon levels should be set for children, as they are more susceptible to ionizing radiation [17]. As radon is nine times heavier than air, small children breathe air closer to the floor and at higher frequency per body mass [18], and are therefore more exposed to radon than adults. Recommendations should be more specific or allowed levels should be lower for houses with children. In addition to radon levels in soil, other parameters, such as climate (insulation hours) have an impact on the ageing of concrete, which may increase or decrease radon flux [19,20]. Indoor radon levels depend on the building material. Thus, a Swedish study showed that radon levels were higher in flats of multi-family dwellings made of concrete than in detached houses made of other materials [21]. Recently, application of granite as decorative material in houses has raised interest in estimation of its radon emissions. The geological origin of granite has a significant impact on the level of emitted radiation. According to a recent study, the contribution of radon concentration from granite is less than 1% [22] if granite is present only in the kitchen. However, trends in modern indoor architecture increase application of granite in corridors, stairs, and living rooms. As an aggregate, granite also appears in concrete production [23]. The range of radon emission measurements show that the highest values may be detected in granites from Brazil (Carmen Red, Red Dragon, Golden Leaf) [22]. In some areas like Egypt, higher radioactivity is also measured in marbles [24]. 3. Radioactivity of fly ash in concrete and bricks Coal burning by-products, such as fly ash, significantly increase the level of toxic metals and ionizing radiation in the living environment by concentrating elements like uranium (235U, 238U), thorium (232Th), and potassium (40K) by a factor of 20e25 compared to levels in the original peat [23,25]. The levels of these radionuclides may vary two orders of magnitude, depending on the coal origin [26]. Globally, about 280 million tonnes of coal ash is produced annually, of which 40 million tonnes is used in the production of bricks, cement, road stabilizers, road fill, and asphalt mix [27]. From such sources, individual doses of radiation exposure to general public can be about 100 mSv/y [28,29]. However, there is no European programme which gives an estimation of exposure of general public in Europe based on radiation exposure from construction products. Cement is successfully replaced with fly ash in concrete in the range from 10% to up to 80%. High-volume fly ash concrete is limited to placements where durability is not a concern, such as indoor walls (Portland Cement Association, http://www. concretethinker.com/technicalbrief/Supplementary-CementitiousMaterials.aspx) [30]. As fly ash is a hazardous waste which contains toxic metals and radionuclides, its use as a construction material is encouraged as
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a form of waste management. Thus, fly ash has become zero-cost raw building material, which would otherwise require special waste management [31] due to its physical and chemical characteristics. Construction products containing fly ash are recognised by the European Commission Directorate for Radiation Protection as possible sources of radioactivity [23]. In some countries like Israel, Finland, or Denmark, national standards define the annual effective doset of 0.3mSv for all routes of exposure to radiation which originates from construction products [31,32]. Studies which evaluate the use of fly ash in the production of concrete and light concrete agree that such technology is in favour both from economical and environmental reasons. However, these technologies should be accompanied by adequate radiation protection measurements such as regular radioactivity measurements of fly ash for each new deliver from thermal plants, as radioactivity varies between coal sources [31e34]. As there are measurable differences in radioactivity between Portland cements containing 3%, 10%, and 20% of fly ash [34,35], such measurements are crucial. Even in higher proportions than in concrete production, fly ash is used in the production of ceramic materials [36,37]. A combination of zircon and fly ash in ceramic production may in the future lead to higher radioactivity emissions, which can be avoided by calculations of predictable radioactivity, depending on their mineral characteristics and radionuclide levels. Indoor radon levels are higher in houses made of bricks containing fly ash than in houses made of concrete containing fly ash [38]. Fly ash bricks may reach radioactivity of 300 Bq/kg of 226Ra in dependence of thermal power coal origin [39]. Radon activities in houses built using fly ash and slag in the period from 1850 to 1930 ranged from 55 to 426 Bq m3 per year, while in more recent buildings without ash and slag the range was between 16 and 67 Bq m3 [40]. 4. Zircon Zircon (zirconium silicate) is a mineral which is often used as opacifier and pigment in the production of ceramic tiles. Its high level of radioactivity is due to a specific crystal structure, which incorporates uranium and thorium. Radiation emissions from ceramic tiles are specific, as radon is locked up in tile by a glass-like matrix during the process of vitrification [41], which means that gamma-radiation is the basic radiation type. As radioactivity of zircon varies due to different geological origin, in order to control levels of exposure there are activities which should in future limit the upper mass of zircon in porcelain/ceramics [42]. Studies on radioactivity of ceramics which contain zircon show that despite the fact that radioactivity of ceramic tiles containing zircon minerals in majority of cases are within limits recommended by the European Commission, there are also examples of those which are above the recommended values [43e47]. Additionally, data on occupational radiation exposure of subjects working in shops selling tiles are anecdotal [48]. 5. Nanoparticles in indoor plasters/concrete and floors Nanoparticles could be of natural and man-made origin with a size of less than 100 nm. Their physical and chemical characteristics depend on the size, composition, morphology/shape, and surface properties [49]. The main difference between natural and man-made nanoparticles is in their chemical composition and geometrical forms. Contrarily to natural nanoparticles, which are in 60% of volume sea salt and soil [50,51], that means chrystals or spheroids, artificial nanoparticles produced for application in different technologies (electronics, medicine, construction) contain
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toxic substances (mostly metal or silica oxides and carbon) and have the form of nets and tubes [52]. Exposure to nanoparticles from fly ash may lead to inflammatory effects [53]. In an animal model, it is shown that when inhaled, nanoparticles diffused from the lungs to blood circulation [54]. Nanoparticles are transplacental agents [55,56], which may disturb brain development in the foetus [57]. Silica and TiO2 nanoparticles may also cause genome damage [58,59]. Although silicosis [60] is a well-known disease related to exposure to silica fibres, the health risks related to silica nanoparticles are unknown. Available experimental studies show that silica particles have specific routs of bioaccumulation [61]. Silica nanoparticles in the size from 20 nm to 80 nm, which are in application as cement additives, have been shown to cause cytotoxicity and oxidative stress in hepatic cells [62]. It is also interesting to note that nanoparticles used in radiotherapy of cancer enhance the effects of ionizing radiation [63,64]. Nanoparticles have recently been used in paints and scratch resistance floors, as silica nanoparticles enable transparent coating with no impact on genuine wood colour and texture [65]. Silica nanoparticles and carbon nanotubes have also been introduced in the production of cement mortars and nanoconcrete [66e68], especially because they increase its quality when higher percentage of fly ash is used [69]. It is known that TiO2 is a toxic agent [70]; however, it is used in brick industry. Addition of TiO2 nanoparticles in production of adobe bricks as environmentally friendly construction products, gives them new physical characteristic which enable their usage not only in arid climates [71]. However, whether concrete or such bricks emit nanoparticles during the ageing process is not known. The European Federation of Building and Wood Workers and the European Construction Industry Federation performed an evaluation of the use of nanoparticles in construction industry and on safety issues. The conclusion of this evaluation was that: (a) marketing and application of nanoparticles will grow; (b) information on nanoparticle composition is generally lacking; and (c) as health risks for workers involved in building and for consumers are unknown, precautionary approach is suggested [65,72]. 6. Additives in concrete Better physical and mechanical characteristics of concretes and mortars could be achieved by different chemical additives such as antifreezes, superplastisazers, acryl, polypropylene, glass, steel and other fibres and polystyrene beads. Some of these compounds are used in construction of residential buildings. Generally, additives are most often composed of a variety of different molecules which formulaes are frequently unknown and protected for proprietary reasons [73]. Consequently, for example impact of additives on radionuclides solubility in concrete is actually unknown which is significant information considering application of fly ash in its production. Additionally, there is no data on measurements whether any of additives in concretes or mortars evaporate due to wall heating, ageing or drilling. Despite the fact that polystyrene beads are in application for concrete production it seems that the major source of styrene emission are polystyrene pads used for insulating under the final floor covering and in walls [74]. There are some aspects of air quality control on which there is very little data such as possibility of elimination of ammonia levels in indoor air by extra drying of concrete in which urea-based antifreeze substance are added [75,76]. Levels of 0.11 ppm measured in such buildings are according to USA Environmental protection Agency recommended for preliminary remedation actions [77] as ammonia may cause respiratory problems especially in vulnerable subpopulations such as subjects suffering from asthma.
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It is also worth to mention that in contradiction to producers’ declaration for some additives as non-toxic compounds, still in case of occupational overexposure measures of urgent medical help are frequently prescribed.
7. Discussion Indoor air exposure to xenobiotics may originate from natural sources, construction products, and human behaviour. Global trends in construction industry encourage application of environmentally and ecologically justified materials and synthetic agents (as additives) which improve the performance of construction products. As humans spend most of their lifetime indoors, aspect of health quality in such radiochemically new microenvironments should be evaluated because exposures even to low doses of xenobiotics may involve different health risks. Especially vulnerable subpopulations are pregnant women (unborn children) and children due to age-related characteristics of bioaccumulation and excretion physiology. Most of indoor radiation is owed to radon emitted from soil and rocks. The significance of lung cancer risk related to indoor radon exposure is recognised, and it seems that in the next decade we can expect beneficial results of launched radon mitigation programmes. As methods which can be applied for mitigation of increased radon levels in existing homes are costly, it could be seen from practice that some countries depend in these efforts on voluntary actions and public education, which can also give good results. Future research should include physiologically based pharmacokinetic (PBPK) models for inhaled radon not only for adults, but also for children [78], as the present models do not include age-related physiological and physical parameters such as higher breathing rate in children and higher exposure because radon is heavier than air and keeps close to the floor [79]. However, in addition to exposure to naturally occurring ionizing radiation, it is disturbing that fly ash, which may contain high levels of radionuclides, is encouraged to be used in cement and brick production as a very favourable waste disposal solution. Fly ash may be a major source of indoor radioactivity, which can be especially dangerous in areas naturally burdened with increased radon levels in soil. In such areas application of fly ash should be strictly controlled. Technological improvements in the production of highquality concretes, which allowed replacement of a high percentage of cement with fly ash have to be followed by regulation of obligatory radiation level measurements. Similarly, radiation levels of porcelain tiles containing fly ash and zircon should also be monitored. In addition to fly ash, within efforts to use industrial waste there is a technological option to use bauxite in concrete production, but as in the case of fly ash, measurement of radioactivity is crucial [80]. The ratio of bauxite used in the production of bricks and cement should be limited by radionuclide levels. Similarly, due to a strong international market of granite and due to diversity in their radioactivity levels [81], more information for customers on possible health risks should be available. The problem has already been recognised by construction industry experts. New technologies introduced for efficient elimination of radon release from cement containing fly ash by additives such as barite, zeolite, or ferric oxide [82] or by introduction of snow as additive, are already available [83]. The very fact that technical and technological possibility to use waste as a construction product exists, is not always possible to put directly in practice without careful evaluation and justification, as some waste materials can be sources of indoor contamination. For example, the suggested possibility to use cigarette butts in the production of bricks showed no danger in emission of metals [84].
However, one of major contaminants in cigarette butt, ammonia, is not included in measurements [85]. Emission of additives from cement/concrete and other construction products which improve the stability of construction, durability of materials or their noise- and energy-related characteristics should be combined with measurements of contaminants in materials for finishing and furnishing of interiors [86]. Launching the data base of such compounds intended for use in construction sector would facilitate an insight into the complexity of indoor air quality and help engineers and architects in selecting optimal solutions. Volatile organic compounds are a large group of substances used in finishing and furnishing. It is also a group of chemicals which is supported with the largest number of investigations on health effects, and legislation is already in practice. The timing of measurements of VOCs in buildings is of major significance, as the highest levels of emission are present during the first few months after the finishing and furnishing [87]. This fact should be followed by a regulation defining that a building use permit is issued when the levels of selected VOCs levels drop below levels associated with health risks. Nanoparticles are applied in the majority of production processes and are present in a large amount of industrial products, from cosmetics to space exploration. The possibility to improve physical and chemical characteristics of construction products by nanoparticles launched their application in building and finishing of buildings. There is still no epidemiological evidence of health risks related to exposure to indoor nanoparticles. However, the major problem with their application in outdoor plasters is the washing out of nanoparticles, as their increased levels in waste waters may have a significant impact on wildlife because decontamination of waste waters dose not includes their elimination. In order to improve the quality of indoor air and to prevent future application of materials which do not meet building health and safety requirements, it is of great importance to intensify collaboration between governmental and non-governmental bodies, manufacturers, scientific institutions, and engineers/ architects. Engineers and architects should be educated to follow producer information about the composition of construction products on selection, and especially about the type and duration of emissions unfavourable for health. Although energy-saving certificates for buildings are available, there are still no certificates for healthy building interior certificates. In March 2011 European Union adopted Construction Products Regulation which lays down uniform health, safety and environmental safety data for building materials. This is a significant step forward in recognising current problems in building, but much more has to be invested in the definition of flying ash percentage in concrete and in regulations on radiation level measurement in order to prevent that construction industry evolve to the world’s largest waste management industry and that construction works become world’s largest waste disposal facility. Vice versa, as construction engineering is current producer of almost 50% of waste [88] application of toxic and radioactive agents may lead to redefinition of such waste as a hazardous one and could demand special waste disposals. Current technology and scientific support enables realization of crucial task in balancing current building practice, indoor life quality and private and general sector interests. 8. Conclusion Recognition of need for building material supervision could be seen in Europe via recently prepared Basic Safety Standards and Construction Product Regulation which will include measurements of
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construction material radioactivity and other documents which will control chemicals (nanoparticles, cement additives, VOCs, floor fillers, isolation substances) currently applied in civil engineering practice. Such activities should be accompanied by incorporating measurements of total radiochemical exposure upon future dwellers in building projects. Furthermore, issuing a using permit for building should be approved only if emissions of chemicals from materials used in interior construction have reached levels which are not related to increased health risk. This new approach also requests reevaluation of occupational exposure monitoring in building industry due to numerous application of new xenobiotics such as superplasticisers (polycarboxylate ether), nanomaterials, fibres and building materials with possible increased natural radioactivity. References [1] Huchcroft SA, Mao Y, Semenciw R. Cancer and the environment: ten topics in environmental cancer epidemiology in Canada. 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The potential risks of nanomaterials: a review carried out for ECETOC. Particle Fibre Tox 2006;3(11):1e23. [50] Hosokawa M, Nogi K, Naito M, Yokoyama T, editors. Nanoparticle technology handbook. UK: Elsevier; 2007. [51] Navarro E, Baun A, Behra R, Hartmann NB, Filser J, Miao AJ, et al. Environmental behavior and ecotoxicology of engineered nanoparticles to algae, plants and fungi. Ecotoxicology 2008;17:372e86. [52] Pacheco-Torgal F, Jalali S. Nanotechnology: advantages and drawbacks in the field of construction and building materials. Contsruction Building Mater 2011;25:582e90. [53] Gilmour MI, O’Connor S, Dick CA, Miller CA, Linak WP. Differential pulmonary inflammation and in vitro cytotoxicity of size-fractionated fly ash particles from pulverized coal combustion. J Air Waste Manag Assoc 2004;54(3):286e95. [54] Nemmar A, Vanbilloen H, Hoylaerts MF, Hoet PH, Verbruggen A, Nemery B. Passage of intratracheally instilled ultrafine particles from the lung into the systemic circulation in hamster. Am J Respir Crit Care Med 2001;164(9):1665e8. [55] Oberdörster G, Sharp Z, Atudorei V, Elder A, Gelein R, Kreyling W, et al. Translocation of inhaled ultrafine particles to the brain. Inhal Toxicol 2004; 16(6e7):437e45. [56] Hagens WI, Oomen AG, de Jong WH, Cassee FR, Sips AJ. What do we (need to) know about the kinetic properties of nanoparticles in the body? Regul Toxicol Pharmacol 2007;49:217e29. [57] Takahashi Y, Mizuo K, Shinkai Y, Oshio S, Takeda K. Prenatal exposure to titanium dioxide nanoparticles increases dopamine levels in the prefrontal cortex and neostriatum of mice. J Toxicol Sci 2010;35(5):749e56.
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[58] Gong C, Tao G, Yang L, Liu J, Liu Q, Zhuang Z. SiO(2) nanoparticles induce global genomic hypomethylation in HaCaT cells. Biochem Biophys Res Commun 2010;397(3):397e400. [59] Trouiller B, Reliene R, Westbrook A, Solaimani P, Schiesti RH. Titanium dioxide nanoparticles induce DNA damage and genetic instability in vivo in mice. Cancer Res 2009;69(22):8784e9. [60] Thomas CR, Kelley TR. A brief review of silicosis in the United States. Environ Health Insights 2010;18(4):21e6. [61] Choi J, Zheng Q, Katz HE, Guilarte TR. Silica-Based nanoparticle uptake and cellular response by primary microglia. Environ Health Perspect 2010;118:589e95. [62] Ye Y, Liu J, Xu J, Sun L, Chen M, Lan M. Nano-SiO2 induces apoptosis via activation of p53 and bax mediated by oxidative stress in human hepatic cell line. Toxicology 2010;24:751e8. [63] Berbeco RI, Ngwa W, Makrigiorgos GM. Localized dose enhancement to tumor blood vessel endothelial cells via megavoltage x rays and targeted gold nano particles: new potential for external beam therapy. Int J Radiat Oncol Biol Phys 2010;78(3):S649e50. [64] Hamoudehm M, Kamleh MA, Diab R, Fessi H. Radionuclides delivery systems for nuclear imaging and radiotherapy of cancer. Adv Drug Deliv Rev 2008;60: 1329e46. [65] vanBroekhuizen P, vanBroekhuizen F, Cornelissen R, Reijnders L. Use of nanoparticles in the European construction industry and some occupational health aspects thereof. J Nanopart Res 2011;13(2):447e62. [66] Jo BW, Kim CH, Park TG. Characteristics of cement mortar with nano-SiO2 particles. Construction Building Mater 2007;21:1351e5. [67] Nazari A, Riahi S, Shamekhi SF, Khademno A. Assessment of the effects of the cement paste composite in presence TiO2 nanoparticles. J Am Sci 2010;6(4):43e6. [68] Morsy MS, Aglan HA. Development and characterization of nanostucturedeperlite-cementitious surface compounds. J Mater Sci 2007;42: 10188e95. [69] Chaipanich A, Nochaiya T, Wongkeo W, Torkittikul P. Compressive strength and microstructure of carbon nanotubesefly ash cement composites. Mater Sci Eng 2010;527:1063e7. [70] Grassian V, O’Shaughnessy P, Adamcakova-Dodd A, Pettibone J, Thorne P. Inhalation exposure study of titanium dioxide nanoparticles with a primary particle size of 2e5 nm. Environ Health Perpsect 2007;115:397e402. [71] Calabria AJ, Wl Vasconcelos, Daniel DJ, Chater R, McPhail D, Boccaccini AR. Synthesis of solegel titania bactericide coatings on adobe brick. Construction Building Mater 2010;24:384e9. [72] vanBroekhuizen F, vanBroekhuizen P. Nanotechnology in the European construction industry state of the art 2009. Executive summary, European Federation of Building and Wood Workers and European Construction Industry Federation.
[73] Glaus MA, Van Loon LR. A generic procedure for the assessment of the effect of concrete admixtures on the retention behavior of cement for radionuclides: concept and case studies, in, Nagra technical report NTB 03-09, 2004; Wettingen, Switzerland. [74] Jarnstrom H, Saarela K, Kallikoski P, Pasanen AL. Reference values for indoor air pollutant concentrations in new, residential building in Finland. Atmos Environ 2006;40:7178e91. [75] Bai Z, Dong Y, Wang Z, Zhu T. Emission of ammonia from indoor concrete wall and assessment of human exposure. Environ Int 2006;32:303e11. [76] Tuomainen M, Tuomainen A, Liesivuori J, Pasanen AL. The 3-year follow-up study in a block of flats e experiences in the use of the Finnish indoor climate classification. Indoor Air 2003;13:136e47. [77] Environmental Protection Agency. Preliminary remediation goals, ammonia. Region IX (2002). United States Environmental Protection Agency; 2002. [78] Yu D, Kim JK. A physiologically based assessment of human exposure to radon released from groundwater. Chemosphere 2004;54(5):639e45. [79] Chen J. Estimated risks of radon-induced lung cancer for different exposure profiles based on the new EPA model. Health Phys 2005;88(4):323e33. [80] Somlai J, Jobbagy V, Kovacs J, Tarjan S, Kovacs T. Radiological aspects of the usability of red mud as building material additive. J Hazard Mater 2008;150: 541e5. [81] Pavlidou S, Koroneos A, Papastefanou C, Christofides G, Stoulo S, Vavelides M. Natural radioactivity of granites used as building materials. J Environ Rad 2006;89:48e60. [82] Deng W, Tian K, Zhang Y, Chen D. Radioactivity in zircon and building tiles. Health Phys 1997;73(2):369e72. [83] Baykal G, Saygili A. A new technique to reduce the radioactivity of fly ash utilized in the construction industry. Fuel 2011;90(4):1612e7. [84] Kadir AA. Possible utilization of cigarette butts in light-weight fired clay bricks, vol. 45. World Academy of Sciences, Engineering and Technology; 2008. pp. 153e157. [85] Stevenson T, Proctor RN. The secret and soul of Marlboro: Phillip Morris and the origins, spread, and denial of nicotine freebasing. Am J Public Health 2008; 98(7):1184e94. [86] Harada K, Hasegawa A, Wei CN, Minamoto K, Noguchi Y, Hara K, et al. A review of indoor air pollution and health problems from the viewpoint of environmental hygiene: focusing on the studies of indoor air environment in Japan compared to those of foreign countries. J Health Sci 2010;56(5): 488e501. [87] Yu C, Crump D. A review of the emission of VOCs from polymeric materials used in buildings. Building Environ 1998;33(6):357e74. [88] European Environmental Agency. Europe’s environment - The fourth assessment, Copenhagen; 2007. State of the environment report No 1/2007.
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Building and Environment journal homepage: www.elsevier.com/locate/buildenv
Radiochemical indoor environment and possible health risks in current building technology Aleksandra Fucic a, *, Lino Fucic b, Jelena Katic a, Ranko Stojkovi c c, Marija Gamulin d, Enes Seferovi ce a
Institute for Medical Research and Occupational Health, Ksaverska c 2, 10 000 Zagreb, Croatia Ministry of Environmental Protection, Physical Planning and Construction, Zagreb, Croatia c Institute “Rudjer Boskovic”, Zagreb, Croatia d Zagreb University Hospital, Zagreb, Croatia e CSS Ltd, Zagreb, Savska c 144a, Croatia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 29 April 2011 Received in revised form 14 June 2011 Accepted 16 June 2011
Tremendous work of civil and environmental engineering has been focused on development of sustainable buildings. From economical and ecological viewpoint, this approach is a significant step forward, but the microenvironment created in such living surroundings may present a complex radiochemical setting, which could be a threat to the health of its occupants. This paper gives overview about levels of indoor radon, insight in risks related with radioactivity of fly ash and zircon, current application of nanoparticles and concrete additives in buildings and their possible impact on human health. As construction engineering is current producer of almost 50% of waste encouragement of incorporation of toxic and radioactive agents in buildings could in future demand redefinition of building construction waste as hazardous and special waste disposals. Collaboration between governmental and nongovernmental bodies, manufacturers, scientific institutions, and chartered engineers is needed in order to find balance between quality of indoor air, and to enable maintaining of high health standards by application of non-toxic or non-carcinogenic building materials that meet energy efficiency, building structure stability and security requirements. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Indoor radon Fly ash Radionuclides Nanoparticles Human health Concrete additive
1. Introduction Construction products and materials as well as building technologies used currently in developed construction economies create complex radiochemical microenvironmental living settings. Outdoor air pollution in epidemiological studies has clearly been demonstrated as a health risk factor [1], but it has been recognized that indoor air quality may have a greater contribution to overall public health [2e4]. Considering that modern lifestyle involves spending most of the time (70e80%) indoors [5], ambient air quality becomes even more significant. Dangerous gases, particles and fibres which are continuously being emitted at room temperature from some building and furnishing materials affect indoor air quality. In addition to indoor radon lifelong exposure, some construction products containing radionuclide can increase indoor exposure to ionizing radiation.
* Corresponding author. Tel.: þ385 14682521; fax: þ385 4673303. E-mail address: [email protected] (A. Fucic). 0360-1323/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2011.06.020
Significant efforts of civil and environmental engineering are focused on development of sustainable buildings. Real estate market demands built environment that meets high visual and aesthetic standards, as well as acceptable noise and energy consumption level by what request application of new construction products. Sophisticated isolating materials and constructions meet public and industry demands regarding noise and cooling/heating energy consumption. Through this process, these so-called selfsufficient homes have become “air-tight” and isolated from interaction with the outer environment more than ever before. From economical and ecological viewpoint this is a significant step forward, but indoor air quality in such closed systems relies on ventilation, type of the heating/cooling system, natural background radiation, and on components of construction products which may emit xenobiotics into the living environment, causing different health problems. Other lifestyle activities and habits in homes, such as use of household products, open fire, and environmental tobacco smoke could also elevate the concentrations of hazardous agents in indoor environment. Over the last 50 years, levels of chemicals suspected as endocrine disruptors have significantly increased in indoor environment, but also in the blood and urine of occupants [6], yet little is known about the monitoring of such indoor
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exposure in everyday life. This is especially significant for early life exposure to indoor pollutants, which could impair the development of the infant immune system and increase the risk of respiratory diseases in children [7]. The aim of present study is to give an insight into indoor microenvironment created by currently used construction products and building technologies which are common in developed construction economies. Indoor radon, fly ash, nanoparticles, zircon, and concrete additives are selected building materials in regard to their impact on human health and prevalence in types of exposures. Volatile organic compounds (VOCs) emission from finishing coatings and furnishing of buildings are not included, but only discussed in relation with construction products. The results of our study may be applied in future as a basic platform for interdisciplinary panel which may provide optimal improvement of building practice from economical, structural, noise, energy saving, and health quality points. 2. Indoor radon Radon is a radioactive gas which naturally occurs in soil and rocks. By entering buildings through cracks in the construction it becomes an indoor phenomenon. In soils which contain high concentrations of radon, indoor exposure is in correlation with increased risk of lung cancer, with an excess relative risk of 10% per 100 Bq m3 [8]. In healthy population it is also possible to measure health risk by estimating genome damage level caused by radiation emitted from radon. Thus, a significant increase in genome damage was shown in children who spent up to 5 h per day in classrooms with radon levels in the range of 900e3200 Bq m3 [9]. Interindividual differences in radiosensitivity to radon have been described in Caucasians who are carriers of gluthatione-S-transferase null genotype, which presence is associated with a three times higher risk of lung cancer after exposure to levels higher than 121 Bq m3 [10]. A synergism between smoking and radon in lung cancer aetiology has been described in several studies, which have also shown an impact of human behaviour on the quality of indoor environment [11e13]. An example of good practice in mitigating indoor radon exposure can be seen in the United Kingdom, where the soil in some areas is responsible of very high indoor radon levels. In 1990, the UK government accepted the National Radiological Protection Board’s (NRPB) advice that remedial measures should be taken in homes with radon levels above the Radon Action Level, which is 200 Bq m3. At the same time, Radon Affected Areas were defined as areas of the country where 1% or more of properties were estimated to be equal to or higher of the Radon Action Level. This programme was based on a publicly financed radon measurement program. The United Kingdom implemented a prevention programme coordinated by the UK Health Protection Agency (HPA), the British Geological Survey (BGS) and Building Research Establishment (BRE), which also prepared new and more detailed maps of radon-affected areas. On the global level, in 2009, the World Health Organization [14] issued a recommendation according to which the Action Level for radon in homes should be reduced to 100 Bq m3. In the European countries where 0.5%e15% of houses have radon concentrations above 200 Bq m3, remedial measures are needed [15]. The key messages of the World Health Organization International Radon project relevant for the construction sector are that: (a) strategies both for radon prevention in new dwellings and mitigationin existing dwellings are needed to achieve an overall risk reduction; (b) professionals in the construction sector are the key players for radon prevention and mitigation; therefore strategies are needed to train them and to ensure their competence in this area; and (c)
research-based guidelines and/or standards for radon prevention and mitigation should be established at the national level. In the same report comparison of different control systems and costeffectiveness are presented in details. One of the important conclusions of this report is that even when cost-effectiveness analysis is not justified on the national level, high levels of radon may be considered as a lung cancer risk on individual bases and remediation should be performed. Although radon mapping in Europe is in progress, it has not been yet started in a number of countries, and this is probably the reason for which the process of preparing regulation or directive on the European level is running slow. The cost-effectiveness of future policies is confirmed, especially if complemented with policies for smoking reduction [16]. Specific provisions in regulations for radon levels should be set for children, as they are more susceptible to ionizing radiation [17]. As radon is nine times heavier than air, small children breathe air closer to the floor and at higher frequency per body mass [18], and are therefore more exposed to radon than adults. Recommendations should be more specific or allowed levels should be lower for houses with children. In addition to radon levels in soil, other parameters, such as climate (insulation hours) have an impact on the ageing of concrete, which may increase or decrease radon flux [19,20]. Indoor radon levels depend on the building material. Thus, a Swedish study showed that radon levels were higher in flats of multi-family dwellings made of concrete than in detached houses made of other materials [21]. Recently, application of granite as decorative material in houses has raised interest in estimation of its radon emissions. The geological origin of granite has a significant impact on the level of emitted radiation. According to a recent study, the contribution of radon concentration from granite is less than 1% [22] if granite is present only in the kitchen. However, trends in modern indoor architecture increase application of granite in corridors, stairs, and living rooms. As an aggregate, granite also appears in concrete production [23]. The range of radon emission measurements show that the highest values may be detected in granites from Brazil (Carmen Red, Red Dragon, Golden Leaf) [22]. In some areas like Egypt, higher radioactivity is also measured in marbles [24]. 3. Radioactivity of fly ash in concrete and bricks Coal burning by-products, such as fly ash, significantly increase the level of toxic metals and ionizing radiation in the living environment by concentrating elements like uranium (235U, 238U), thorium (232Th), and potassium (40K) by a factor of 20e25 compared to levels in the original peat [23,25]. The levels of these radionuclides may vary two orders of magnitude, depending on the coal origin [26]. Globally, about 280 million tonnes of coal ash is produced annually, of which 40 million tonnes is used in the production of bricks, cement, road stabilizers, road fill, and asphalt mix [27]. From such sources, individual doses of radiation exposure to general public can be about 100 mSv/y [28,29]. However, there is no European programme which gives an estimation of exposure of general public in Europe based on radiation exposure from construction products. Cement is successfully replaced with fly ash in concrete in the range from 10% to up to 80%. High-volume fly ash concrete is limited to placements where durability is not a concern, such as indoor walls (Portland Cement Association, http://www. concretethinker.com/technicalbrief/Supplementary-CementitiousMaterials.aspx) [30]. As fly ash is a hazardous waste which contains toxic metals and radionuclides, its use as a construction material is encouraged as
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a form of waste management. Thus, fly ash has become zero-cost raw building material, which would otherwise require special waste management [31] due to its physical and chemical characteristics. Construction products containing fly ash are recognised by the European Commission Directorate for Radiation Protection as possible sources of radioactivity [23]. In some countries like Israel, Finland, or Denmark, national standards define the annual effective doset of 0.3mSv for all routes of exposure to radiation which originates from construction products [31,32]. Studies which evaluate the use of fly ash in the production of concrete and light concrete agree that such technology is in favour both from economical and environmental reasons. However, these technologies should be accompanied by adequate radiation protection measurements such as regular radioactivity measurements of fly ash for each new deliver from thermal plants, as radioactivity varies between coal sources [31e34]. As there are measurable differences in radioactivity between Portland cements containing 3%, 10%, and 20% of fly ash [34,35], such measurements are crucial. Even in higher proportions than in concrete production, fly ash is used in the production of ceramic materials [36,37]. A combination of zircon and fly ash in ceramic production may in the future lead to higher radioactivity emissions, which can be avoided by calculations of predictable radioactivity, depending on their mineral characteristics and radionuclide levels. Indoor radon levels are higher in houses made of bricks containing fly ash than in houses made of concrete containing fly ash [38]. Fly ash bricks may reach radioactivity of 300 Bq/kg of 226Ra in dependence of thermal power coal origin [39]. Radon activities in houses built using fly ash and slag in the period from 1850 to 1930 ranged from 55 to 426 Bq m3 per year, while in more recent buildings without ash and slag the range was between 16 and 67 Bq m3 [40]. 4. Zircon Zircon (zirconium silicate) is a mineral which is often used as opacifier and pigment in the production of ceramic tiles. Its high level of radioactivity is due to a specific crystal structure, which incorporates uranium and thorium. Radiation emissions from ceramic tiles are specific, as radon is locked up in tile by a glass-like matrix during the process of vitrification [41], which means that gamma-radiation is the basic radiation type. As radioactivity of zircon varies due to different geological origin, in order to control levels of exposure there are activities which should in future limit the upper mass of zircon in porcelain/ceramics [42]. Studies on radioactivity of ceramics which contain zircon show that despite the fact that radioactivity of ceramic tiles containing zircon minerals in majority of cases are within limits recommended by the European Commission, there are also examples of those which are above the recommended values [43e47]. Additionally, data on occupational radiation exposure of subjects working in shops selling tiles are anecdotal [48]. 5. Nanoparticles in indoor plasters/concrete and floors Nanoparticles could be of natural and man-made origin with a size of less than 100 nm. Their physical and chemical characteristics depend on the size, composition, morphology/shape, and surface properties [49]. The main difference between natural and man-made nanoparticles is in their chemical composition and geometrical forms. Contrarily to natural nanoparticles, which are in 60% of volume sea salt and soil [50,51], that means chrystals or spheroids, artificial nanoparticles produced for application in different technologies (electronics, medicine, construction) contain
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toxic substances (mostly metal or silica oxides and carbon) and have the form of nets and tubes [52]. Exposure to nanoparticles from fly ash may lead to inflammatory effects [53]. In an animal model, it is shown that when inhaled, nanoparticles diffused from the lungs to blood circulation [54]. Nanoparticles are transplacental agents [55,56], which may disturb brain development in the foetus [57]. Silica and TiO2 nanoparticles may also cause genome damage [58,59]. Although silicosis [60] is a well-known disease related to exposure to silica fibres, the health risks related to silica nanoparticles are unknown. Available experimental studies show that silica particles have specific routs of bioaccumulation [61]. Silica nanoparticles in the size from 20 nm to 80 nm, which are in application as cement additives, have been shown to cause cytotoxicity and oxidative stress in hepatic cells [62]. It is also interesting to note that nanoparticles used in radiotherapy of cancer enhance the effects of ionizing radiation [63,64]. Nanoparticles have recently been used in paints and scratch resistance floors, as silica nanoparticles enable transparent coating with no impact on genuine wood colour and texture [65]. Silica nanoparticles and carbon nanotubes have also been introduced in the production of cement mortars and nanoconcrete [66e68], especially because they increase its quality when higher percentage of fly ash is used [69]. It is known that TiO2 is a toxic agent [70]; however, it is used in brick industry. Addition of TiO2 nanoparticles in production of adobe bricks as environmentally friendly construction products, gives them new physical characteristic which enable their usage not only in arid climates [71]. However, whether concrete or such bricks emit nanoparticles during the ageing process is not known. The European Federation of Building and Wood Workers and the European Construction Industry Federation performed an evaluation of the use of nanoparticles in construction industry and on safety issues. The conclusion of this evaluation was that: (a) marketing and application of nanoparticles will grow; (b) information on nanoparticle composition is generally lacking; and (c) as health risks for workers involved in building and for consumers are unknown, precautionary approach is suggested [65,72]. 6. Additives in concrete Better physical and mechanical characteristics of concretes and mortars could be achieved by different chemical additives such as antifreezes, superplastisazers, acryl, polypropylene, glass, steel and other fibres and polystyrene beads. Some of these compounds are used in construction of residential buildings. Generally, additives are most often composed of a variety of different molecules which formulaes are frequently unknown and protected for proprietary reasons [73]. Consequently, for example impact of additives on radionuclides solubility in concrete is actually unknown which is significant information considering application of fly ash in its production. Additionally, there is no data on measurements whether any of additives in concretes or mortars evaporate due to wall heating, ageing or drilling. Despite the fact that polystyrene beads are in application for concrete production it seems that the major source of styrene emission are polystyrene pads used for insulating under the final floor covering and in walls [74]. There are some aspects of air quality control on which there is very little data such as possibility of elimination of ammonia levels in indoor air by extra drying of concrete in which urea-based antifreeze substance are added [75,76]. Levels of 0.11 ppm measured in such buildings are according to USA Environmental protection Agency recommended for preliminary remedation actions [77] as ammonia may cause respiratory problems especially in vulnerable subpopulations such as subjects suffering from asthma.
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It is also worth to mention that in contradiction to producers’ declaration for some additives as non-toxic compounds, still in case of occupational overexposure measures of urgent medical help are frequently prescribed.
7. Discussion Indoor air exposure to xenobiotics may originate from natural sources, construction products, and human behaviour. Global trends in construction industry encourage application of environmentally and ecologically justified materials and synthetic agents (as additives) which improve the performance of construction products. As humans spend most of their lifetime indoors, aspect of health quality in such radiochemically new microenvironments should be evaluated because exposures even to low doses of xenobiotics may involve different health risks. Especially vulnerable subpopulations are pregnant women (unborn children) and children due to age-related characteristics of bioaccumulation and excretion physiology. Most of indoor radiation is owed to radon emitted from soil and rocks. The significance of lung cancer risk related to indoor radon exposure is recognised, and it seems that in the next decade we can expect beneficial results of launched radon mitigation programmes. As methods which can be applied for mitigation of increased radon levels in existing homes are costly, it could be seen from practice that some countries depend in these efforts on voluntary actions and public education, which can also give good results. Future research should include physiologically based pharmacokinetic (PBPK) models for inhaled radon not only for adults, but also for children [78], as the present models do not include age-related physiological and physical parameters such as higher breathing rate in children and higher exposure because radon is heavier than air and keeps close to the floor [79]. However, in addition to exposure to naturally occurring ionizing radiation, it is disturbing that fly ash, which may contain high levels of radionuclides, is encouraged to be used in cement and brick production as a very favourable waste disposal solution. Fly ash may be a major source of indoor radioactivity, which can be especially dangerous in areas naturally burdened with increased radon levels in soil. In such areas application of fly ash should be strictly controlled. Technological improvements in the production of highquality concretes, which allowed replacement of a high percentage of cement with fly ash have to be followed by regulation of obligatory radiation level measurements. Similarly, radiation levels of porcelain tiles containing fly ash and zircon should also be monitored. In addition to fly ash, within efforts to use industrial waste there is a technological option to use bauxite in concrete production, but as in the case of fly ash, measurement of radioactivity is crucial [80]. The ratio of bauxite used in the production of bricks and cement should be limited by radionuclide levels. Similarly, due to a strong international market of granite and due to diversity in their radioactivity levels [81], more information for customers on possible health risks should be available. The problem has already been recognised by construction industry experts. New technologies introduced for efficient elimination of radon release from cement containing fly ash by additives such as barite, zeolite, or ferric oxide [82] or by introduction of snow as additive, are already available [83]. The very fact that technical and technological possibility to use waste as a construction product exists, is not always possible to put directly in practice without careful evaluation and justification, as some waste materials can be sources of indoor contamination. For example, the suggested possibility to use cigarette butts in the production of bricks showed no danger in emission of metals [84].
However, one of major contaminants in cigarette butt, ammonia, is not included in measurements [85]. Emission of additives from cement/concrete and other construction products which improve the stability of construction, durability of materials or their noise- and energy-related characteristics should be combined with measurements of contaminants in materials for finishing and furnishing of interiors [86]. Launching the data base of such compounds intended for use in construction sector would facilitate an insight into the complexity of indoor air quality and help engineers and architects in selecting optimal solutions. Volatile organic compounds are a large group of substances used in finishing and furnishing. It is also a group of chemicals which is supported with the largest number of investigations on health effects, and legislation is already in practice. The timing of measurements of VOCs in buildings is of major significance, as the highest levels of emission are present during the first few months after the finishing and furnishing [87]. This fact should be followed by a regulation defining that a building use permit is issued when the levels of selected VOCs levels drop below levels associated with health risks. Nanoparticles are applied in the majority of production processes and are present in a large amount of industrial products, from cosmetics to space exploration. The possibility to improve physical and chemical characteristics of construction products by nanoparticles launched their application in building and finishing of buildings. There is still no epidemiological evidence of health risks related to exposure to indoor nanoparticles. However, the major problem with their application in outdoor plasters is the washing out of nanoparticles, as their increased levels in waste waters may have a significant impact on wildlife because decontamination of waste waters dose not includes their elimination. In order to improve the quality of indoor air and to prevent future application of materials which do not meet building health and safety requirements, it is of great importance to intensify collaboration between governmental and non-governmental bodies, manufacturers, scientific institutions, and engineers/ architects. Engineers and architects should be educated to follow producer information about the composition of construction products on selection, and especially about the type and duration of emissions unfavourable for health. Although energy-saving certificates for buildings are available, there are still no certificates for healthy building interior certificates. In March 2011 European Union adopted Construction Products Regulation which lays down uniform health, safety and environmental safety data for building materials. This is a significant step forward in recognising current problems in building, but much more has to be invested in the definition of flying ash percentage in concrete and in regulations on radiation level measurement in order to prevent that construction industry evolve to the world’s largest waste management industry and that construction works become world’s largest waste disposal facility. Vice versa, as construction engineering is current producer of almost 50% of waste [88] application of toxic and radioactive agents may lead to redefinition of such waste as a hazardous one and could demand special waste disposals. Current technology and scientific support enables realization of crucial task in balancing current building practice, indoor life quality and private and general sector interests. 8. Conclusion Recognition of need for building material supervision could be seen in Europe via recently prepared Basic Safety Standards and Construction Product Regulation which will include measurements of
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