Feasibility study of radiation protection guidelines in the use of building materials in the Italian dwellings

The Science of the Total Environment, 45 (1985) 613--620 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

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FEASIBILITY STUDYOF RADIATION PROTECTIONGUIDELINES IN THE USE OF BUILDING MATERIALS IN THE ITALIAN DWELLINGS.

G. CAMPOSVENUTII , S. MANCIOPPI2, S. PIERMATTEI2, S. RISICAI and A.F. SUSANNA2 I I s t i t u t o Superiore di Sanita, Viale Regina Elena, 299 - 00161ROMA (ITALY) 2ENEA-DISP, Via Vitaliano Brancati 48 - 00144 ROMA(ITALY)

ABSTRACT The I t a l i a n situation concerning the indoor radiation exposure is examined. A tentative comparison of the risk connected with radon and radon daughter indoor exposures and other every day l i f e risks is made. The social economic impact of imposing possible constraints on home building industry is also discussed.

INTRODUCTION In the last years great attention has been paid by the international scientif i c community to the indoor exposure of the population. Some I t a l i a n research institutes have been carrying out indoor radiation measurements in some parts of the t e r r i t o r y (ref.1,2,3). From these measurements and from a survey of the natural gamma background (ref.4) conducted in the sixties i t has transpired that there are at least three administrative d i s t r i c t s (the whole I t a l i a n t e r r i t o r y is divided into 21 administrative d i s t r i c t s , called "regions") Lazio, Campania and Umbria, which in some zones show an outdoor terres t r i a l radiation exceeding the normal range of variations. On this basis i t seemed worthwhile to analyse the data and evaluate i t s significance in terms of radiation exposure for the population. Before exploring the opportunity of setting up guidelines governing the use of building materials and the planning of dwellings and taking into consideration the ICRP-39 recommendations, a tentative comparison has been performed between the risk associated with radiations and other sources of risk existing in the every day l i f e . The social-economic impact connected with possible constraints in the use of building materials has also been considered.

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OUTDOOR AND INDOORRADIATION LEVELS As an example in Fig. I the results of gammaradiation background measurements in some districts are reported. I t is interesting to see that there are zones not too far from each other (20-40 km), showing remarkable differences in the geological features, where the exposure rates d i f f e r by a factor 3 or 4 ( i . e . in Umbria, Lazio and Campaniad i s t r i c t s ) . This means that the average exposure in an administrative d i s t r i c t cannot be a significant parameter under these circumstances, but i t is of fundamental importance to perform a detailed analysis of the t e r r i t o r y i f the effective dose equivalent to the population has to be assessed. The largest differences exist in high radiation background zones, while where the radiation background is rather low the exposure is f a i r l y constant throughout the d i s t r i c t .

~

pRh-I

•

.

,%.

Fig. I. Outdoor gammaexposure levels in some I t a l i a n d i s t r i c t s .

The values reported in Fig. I include the cosmic radiation contribution, which has recently been measured (ref.5) on the Trasimeno lake located in Central I t a l y , about 270 m above sea level. The results obtained were in agreement -I with data available in the l i t e r a t u r e (4.7~Rh ). Y

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Measurements carried out to evaluate the gamma indoor exposure show that i t is usual to observe that zones with high r a d i a t i o n background generally show high indoor gamma exposure. As an example i t can be mentioned that the indoor gamma-ray exposure measurements carried out in Orvieto, a medieval town located -I in Umbria, gave an average value of 56/LLRh , while the average indoor exposure -I of Bologna, located in the region of Emilia is around 12~Rh . This could be explained by the fact that dwellings are usually b u i l t with local materials, Consequently, the a c t i v i t y concentrations of b u i l d i n g materials have been measured. In Table I the ranges of a c t i v i t y concentrations in the case of four groups of materials, which are considered representative of the I t a l i a n s i t u a t i o n , are reported: a) t u f f s and "pozzolana", b) stones, c) bricks and d) cements.

TABLE I Ranges of a c t i v i t y concentration in b u i l d i n g materials (Bqkg- I )

(ref.5,6).

Material

Origin

40K

238U

232Th

T u f f s , pozzolana

Lazio Campania Umbria Lazio-Campania-Umbria various regions various regions

1900-2370 1950-2250 1468-1925 4-68

350-390 130-230 136-242 1-38

275-350 85-135 468-541 ---

365-1060 4-780

28-81 10-100

40-148 10-240

Stones Bricks Cements

The f i r s t

group, t u f f s and incoherent t u f f s (pozzolana), represents t y p i c a l

materials of the d i s t r i c t s of Umbria,

Lazio and Campania and the a c t i v i t y con-

centration is considerably higher than other natural b u i l d i n g materials in use in Europe. Bricks are mainly produced in Central I t a l y and values are of the same order of those of other countries. Cements present a wide range of a c t i v i t y concentrations; i t is l i k e l y that "pozzolana" which is commonly added to cements is responsible f o r the highest a c t i v i t y concentration. At the moment i t is not possible to give estimates f o r the t o t a l amount of t u f f s and "pozzolana" used, nor of other b u i l d i n g materials. However, assessing the exposure of the population on the basis of the amount of materials used in the home b u i l d i n g industry is equally u n l i k e l y .

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RADONMEASUREMENTS As far as radon and equilibrium equivalent radon concentration measurements in I t a l i a n dwellings are concerned, data exists in the literature and new data w i l l be presented during this Seminar . Although this data is far from d e f i n i t i ve, even in cases now considered as the worst cases (dwellings b u i l t with tuffs) radon concentration does not seem to be as high as in some other countries. Calculation models and measurements have been planned for the future in order to try to correlate the a c t i v i t y concentration in building materials and in the s o i l , with the radon and equilibrium equivalent radon concentration indoor, taking into account the various parameters involved. Efforts shall also be made to estimate the equilibrium factor in various situations. The correlation which presumably exists between the equilibrium factor and the climate has not yet been thoroughly investigated. In any case i t must be pointed out that the districts under consideration, where the highest concentration values have been measured, show a very mild climate

(averagetemperature

around 15°C).

RISK EVALUATION A rough but very simple risk evaluation which can be performed in case of radon exposures, is to assume the equilibrium equivalent radon concentration value of 200 Bqm-3 (corresponding to 20 mSvy- I ) suggested by the ICRP in the Publication n. 39, as an action level in case of f a i r l y simple remedial action. This figure corresponds to a probability of 3.3 10-4 fatal events per year. In order to have more familiar terms of reference the risk associated with radon can be compared with other more familiar risks such as home and motor vehicle accidents. According to a recent I t a l i a n estimate, fatal domestic accidents vary from 4000 to 7000 per year which corresponds to a frequency of (0.6~I.2~ .10-4 fatal events per year, while for motor vehicle accidents, the frequency of fatal events is around 2 10-4 (ref.7) per year. This comparison is rather crude: annual probability of fatal events was considered without taking into account the number of l i f e years lost for each cause, which is a more significant parameter, and in the case of radon the latency period has been neglected. Moreover the probability of fatal events (case of radon) is

being compared

with the frequency of events (domestic or motor vehicle accidents) in a year.

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Another point is that accidental risk due to an industrialised way of l i f e is being compared with a risk which has always existed (Central I t a l i a n villages in the Middle Ages were certainly b u i l t with t u f f s ) . From this simple analysis i t appears, however, that the l i m i t suggested by ICRP gives rise to a risk which is of the same order of magnitude as the risks mentioned above. I t has to be pointed out that measures for the reduction of home and motor vehicle accidents w i l l be taken in our country through educational campaigns. The authors'opinion is that the radon control problem could be dealt with more adequately together with indoor exposure to a i r pollutants generated from various chemical contained in household products, furniture, t e x t i l e s , building materials (asbestos, formaldheide), tobacco smoke, carbon dioxide, etc. Anyhow the authors are f u l l y aware that i t is rather d i f f i c u l t to compare the risk from radon and from other toxic substances existing indoors as at least one common term of reference should be established. However in some countries (ref.8,9) guidelines for building regulations regarding a i r quality have been released and a strategy has been put forward for the reduction of toxic emission from building materials.

SOCIAL ECONOMICIMPACT In the past years the problem of building new houses has been rather severe in I t a l y . A census carried out in 1981 showed that at least 5% of I t a l i a n families l i v e with other families. This percentage can reach 10% in towns with a population above 100.000 inhabitants. The census also revealed that 20% of dwellings exist which are not occupied or are used as resort houses. I t is rather d i f f i c u l t , almost impossible, to make a forecast of the future development of the building industry; however i t can be said that a housing problem does exist for young people and young couples in big towns. This is an important point to be kept in mind in deciding possible l i m i t a tions both in the building of houses and in the use of certain types of buildin~ materials. Moreover i t is necessary to underline that tuffs and "pozzolana" are currently being used as building materials in Central I t a l y and that there is a considerable number of small towns, villages of great historical and architectural interest b u i l t with these materials which represent a typical feature

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of the t e r r i t o r y and which must be saved. Another point to mention is that an accurate and complete screening of the dwellings existing in the high level background d i s t r i c t s cannot be performed in our country as the regional health and safety services are not adequate at the moment to f u l l f i l

such a task. This consideration limits to a certain ex-

tent the way in which the action levels could be put into force. Finally, i t must always be considered that the general public is not well acquainted with risks connected with radiation so that great attention should be paid to these aspects before undertaking any type of action in order to avoid unproductive concern.

CONCLUSIONS From the research work carried out and from the analysis of data, although not complete, one can argue that I t a l i a n indoor exposure levels can be estimated to lay within the average values of the indoor exposures existing at i n t e r national level. A real radiation protection problem deriving from exposure to external i r radiation and from inhalation of radon and radon daughter products, seems to be limited at the moment to well defined areas, which show peculiar geological characteristics. Obviously one cannot exclude that as the research work progresses new areas worth investigating could appear. From what has been said the following points can be singled out. Efforts should be made to evaluate an average value of the indoor radiation exposure on a national basis, then systematical research work should be performed in areas showing indoor levels s i g n i f i c a n t l y above the average value. In particular the dependence of the equilibrium factor from the various parameters involved should be carefully investigated as well as the role played by the soil in the determination of the equilibrium equivalent radon concentration indoors. In this context the setting up of investigation levels along the line of the suggestions contained in the ICRP Publication n. 39 would be highly desirable in order to separate exposures which require investigation from those which do not. In any case i t seems reasonable to exclude a systematic survey of the dwellings as in some countries, and to concentrate the efforts on a representa-

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tive sample. I t has not, in fact, been demostrated that the risk situation existing in some areas j u s t i f i e s the effort. Moreover the country is not prepared to take on such a financial and organization burden. Any action which could be undertaken in the areas identified as at risk must have the agreement and support of local authorities. The actions which could be identified are:

for new dwellings, possible

limitations in the use of some building materials and in the exploitation of some local quarries. For old houses, an optimization process should be devised. Anyhow the only possible interventions should be where the permission of restoration or renewal has been asked. At that moment the local authorities could put some constraints on the materials to be used and requirements for the construction of the interiors. Finally a focal point should be an improvement of the quality of the indoor a i r . The radon and radon daughter pollution problem could be studied together with the problem of other toxic pollutants: like sigarette smoke, paints, household products, t e x t i l e s etc., in order to arrive at a d e f i n i t i o n of suitable indoor a i r standards. This is surely a goal to be achieved at a regional level with the cooperation of all the research i n s t i t u t i o n s active in various fields in the framework of a wider program aimed at the improvement of human l i f e . I t is deemed that on this more general subject educational campaigns to be carried out also in the schools, could be helpful in reach this aim.

REFERENCES I G. Sciocchetti, F. Scacco, P.G. Baldassini, L. Monte and R. Sarao, Rad. Prot. Dosimetry, 7 (1983) 347-350. 2 G. Campos Venuti, S. C o l i l l i , A. Grisanti, G. Grisanti, G. Monteleone, S. Risica, G. Gobbi, M.P. Leogrande, A. Antonini and R. Borio, Rad. Prot. Dosimet r y , 7 (1983) 971-974. 3 G. Busuoli, L. Lembo, R. Nanni and I. Sermenghi, Rad. Prot. Dosimetry, 7

(1983) 313-316. 4 A. Cardinale, G. Cortellessa, F. Gera, O. l l a r i and G. Lembo, Natural Radiation Environment, Proceedings of the IInd International Symposium on the Natural Radiation Environment 0972) 421-440. 5 G. Campos Venuti, S. C o l i l l i , A. Grisanti, G. Grisanti, G. Monteleone, S. Risica, G. Gobbi, M.P. Leogrande, A. Antonini and R. Borio, Compactsof the Vlth International Congress of the IRPA, Berlin, 1984, 84-87.

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6 G. Sciocchetti, G.F. Clemente, G. Ingrao, F. Scacco, Health Physics, 45 (1983) 385-388. 7 Annuario s t a t i s t i c o italiano Roma, 400 pp~980, 8 I. Andersen, L. Seedorff, A. Skov, Environment Int. 8 (1982) 11-16. 9 J.L. Repace, Environment Int. 8 (1982) 21-36.