ECRS : European Commission Radon Software for the evaluation of the risk and the countermeasures associated with the exposure to radon in the dwellings

Author(s):

Centre d'Etude sur l'Evaluation de la Protection dans le domaine Nucléaire (CEPN) and NRPB

Summary:

Exposure to radon in dwellings is estimated to be the second most important cause of lung cancer. For a given exposure scenario, and a population with specific demographic and smoking characteristics, the calculation of radon risks is not straightforward. ECRS performs lung cancer risk calculations specific to European populations for various exposure profiles. It also calculates the reduction in risk that would arise by applying radon countermeasures in dwellings.

Price

The software is distributed at production cost. Any inquiry should be sent to ecrs@cepn.asso.fr

Technical specification

ECRS is a Windows based tool for PCs. It will run under any Windows 95, 98, 2000 and NT 4 system

Further details

The aim of ECRS is to provide a flexible and easy-to-use tool for the individual quantification of risk related to radon exposure in dwellings based upon current information on radon epidemiology, radon dosimetry, demography, and countermeasure efficiency.

The software has been designed to perform lung cancer risk calculations specific to European populations for various exposure profiles and to evaluate, in terms of risk reduction, the effects of various countermeasures in dwellings. It contains a database from a wide selection of countries, but it also allows the user to input alternative data and model parameters.

This software was the result of a joint project partly supported by the European Commission Radiation Protection Programme, involving CEPN and NRPB.

The calculations

The software is able to evaluate the risk of fatal lung cancer associated with individual or collective exposure to radon.

The individual risk calculation determines, for a person of given age, sex and tobacco consumption, the excess risk of fatal lung cancer for a given exposure profile.

The collective risk calculation determines the excess risk of fatal lung cancer for each occupant of a dwelling, for an exposure profile derived from data describing the dwelling, its occupancy, and the chosen countermeasures.

Both the individual and collective risk calculations may be performed using one of the two following classical approaches:

The 'epidemiological' approach in which the risk is obtained directly from the radon exposure data using a risk model derived from epidemiological studies of uranium miners.

The dosimetric (or 'somatic') approach in which the elementary risk is derived from the radon exposure data

through the successive use of a dosimetric model and a somatic effects model.

In both cases, the modifying effect of tobacco consumption on the risk of lung cancer associated with radon exposure is adjusted for by the use of two models. Firstly, a smoking risk model, which adjusts the risk of fatal lung cancer according to the smoking status (non smoker, smoker, ex smoker) of the exposed individual, and secondly, a tobacco-radon interaction model.

ECRS is thus able to perform four main types of calculation, based on different combinations of individual or collective exposure and 'epidemiological' or 'somatic' approach.

 

Calculations available	Countermeasures
Individual Epidemiological	No
Individual Somatic	No
Collective Epidemiological	Yes
Collective Somatic	Yes

The Models

Dosimetric approach

Dosimetric model. The dosimetric model is a radon specific model developed by the NRPB on the basis of the model used to describe and validate the human respiratory tract model recommended in 1994 by the International Commission on Radiological Protection (ICRP) in its publication 66 ¹.

This model relies on various parameters specific to the exposed individual (age, sex, activity level, nose or mouth breathing) together with parameters describing the radon progeny aerosol. It also takes into account the radiation weighting factor for alpha particles and factors describing the relative radiosensitivity of the three lung compartments.

Somatic model. The somatic model is the dose-effect relationship model published in 1990 by the National Academy of Sciences of the United States in its BEIR V report ².

This multiplicative model determines the excess risk of fatal lung cancer associated with a given lung equivalent dose, as a fraction of the relative increase in the average fatal lung cancer risk for the population. The use of such a model requires demographic data of lung cancer mortality (mixing smokers, non-smokers and ex smokers) specific to the selected population.

Epidemiological approach

The epidemiological models are the two radon specific exposure-risk relationship models published in 1999 by the National Academy of Sciences of the United States in its BEIR VI report ³ as well as, for the sake of comparison, the model published in 1988 by the same institution in its BEIR IV report ⁴. These multiplicative models also require demographic data on lung cancer mortality for the population under consideration.

Tobacco exposure

Smoking risk model. The tobacco exposure-risk relationship model was published by Doll and Peto ⁵ in 1994. This model provides a measure of the excess risk of fatal lung cancer associated with smoking status (smoker and ex smoker). This multiplicative model also requires demographic data on lung cancer mortality for the population under consideration. The evaluation of the fatal lung cancer risk of a non-smoker on the basis of the population demographic data of lung cancer mortality also requires information on the distribution of tobacco consumption in the population.

Tobacco-radon interaction. The tobacco-radon interaction model was proposed by Lubin et al ⁶ in 1994. This model allows interaction between radon and tobacco exposure to be modelled in a purely additive, sub-multiplicative, or purely multiplicative way using a single continuous parameter.

Radon exposure model

The collective exposure of the occupants of a dwelling is determined by an exposure model that uses information on the age and sex of the occupants and also the number and type of rooms (kitchen, living room, and bedroom) in the dwelling. The room type is used to determine the equilibrium factor and the aerosol characteristics. Additionally, for each room, the average concentration of radon-gas is required (this is adjusted using an ad-hoc factor in case of a measurement of a below one-year duration), and the rooms occupancy (also the time spent in each activity level in case of the use of the dosimetric approach).

The Countermeasures

The impact of a countermeasure on the radon exposure (countermeasure efficiency) is described by the expected relative reduction of the radon average concentration in the dwelling together with the expected duration of this reduction. Additional parameters describe the initial investment cost, the annual utilisation cost, and the periodical renewal cost associated with the countermeasure in order to calculate the total cost of the considered countermeasure over the period of interest.

The Database System

All the underlying data are stored in a database system that allows the user to examine and modify them, as well as to create new datasets. The database contains demographic data, extracted mainly from the World Health Organisation (WHO) mortality databank ⁷, data describing the models presented above, and information regarding the countermeasures. It also contains tobacco consumption data from WHO [8], for most members states of the European Union.

Data related to a particular calculation, e.g., information on the exposed individuals and the characteristics of the dwelling, the underlying datasets selected, along with the corresponding calculation results, are also stored in the database and may be recalled and examined at any time.

The Results

Risk indicators

The principal risk indicators calculated by the software fall into two categories relating to whole life mortality risk and loss of life expectancy.

The whole life mortality risk indicators present the whole life risk of fatal lung cancer in case of exposure to radon, without any exposure, and in case of exposure to tobacco alone. The excess lung cancer mortality attributable to each of those sources of exposure is also determined, as well as the average number of years of life lost in case of a death attributable to one of these exposure sources.

The loss of life expectancy indicators present the average number of years of life lost due to fatal lung cancer attributable to radon exposure or exposure to tobacco alone. The life expectancy in case of exposure to radon, without any exposure, and in case of exposure to tobacco alone are also reported.

Cost-benefit analysis of countermeasure efficiency

A system of monetary value of human life is used to assign a monetary value to the loss of life expectancy associated with a given exposure (residual detriment). The sum, for each exposure situation, of the total cost (investment, renewal, annual cost,?) of a potential countermeasure and the monetary value of residual detriment is calculated. This enables the identification of the most cost-effective countermeasure, that is, the one that

minimises the sum of the monetary value of residual detriment and the cost of protection.

 

The identification of the most cost-effective countermeasures

References

1 ICRP, Human respiratory tract model for radiological protection, Pergamon Press, Oxford (1994), ICRP Publication 66.

2 BEIR, Health effects of exposure to low levels of ionizing radiation, National Academy Press, Washington D.C. (1990), BEIR V, Committee on the Biological Effects of Ionizing Radiations.

3 BEIR, Health effects of exposure to Radon, National Academy Press, Washington D.C. (1999), BEIR VI, Committee on Health Risks of Exposure to Radon.

4 BEIR, Health effects of Radon and other internally deposited alpha-emitters, National Academy Press, Washington D.C. (1988), BEIR IV, Committee on the Biological Effects of Ionizing Radiations.

5 R. Doll et al., Mortality in relation to smoking: 40 years observations on male British doctors, BMJ, (1994), vol. 309, pp. 901-911.

6 J.H. Lubin, J.D. Boice, C. Edling et al., Radon and lung cancer risk: A joint analysis of 11 underground miners studies, NIH, Washington DC, (1994), Publication No. 94-3644.

7 WHO, Mortality Databank, World Health Organisation, Geneva, (1998).

8 WHO, Tobacco alert, World Health Organisation, Geneva, (1996), Special Issue of the World no-tobacco day 1996.

Last reviewed: 24 May 2010