4 4 7 Assessing the radiation risk to workers exposed to thorium • C. CHALLETON • A. BIAU (IRSN) • S. FOUCHARD (IRSN) • J.-R. JOURDAIN (IRSN) DE VATHAIRE (IRSN) • P. BOISSON (IRSN) • C. COSSONNET (IRSN) • A. RANNOU (IRSN) • M. BOURGUIGNON (OPRI) Protection of human life n the context of actual or suspected situations of Handling monazite was brought to a halt in the I exposure to ionizing radiation, requests for health last phase of the company as the lighters were risk assessments have been made of the public assembled from purchased components. So in experts in the field, OPRI and/or IPSN, that were principle two different risk periods relating to merged to form IRSN in 2002. Audits were carried thorium can be distinguished for the site employ- out jointly by OPRI and IPSN at Pargny-sur-Saulx in ees and the local population: response to the demand made by the Prefect of the • in an early period (1934-1970), the potential Champagne-Ardennes Region. In 1997 drums of exposure and contamination risk was severe radioactive waste were found on the site of Orflam- because the thorium ore was being handled; Plast, a company now in liquidation, revealing the • from the 1970s onwards, the risk of external past exposure of its former workforce that had been exposure was greater than that of internal con- unknown and whose severity had to be assessed. tamination on the Orflam-Plast site, although the risk presented by the presence of thorium in the dike leaching waters is an unknown quantity. It was thus essential that a radiolog- ical risk assessment be made. IRSN carried out a series of surveys from 1997 un- The records of the former Orflam-Plast manufac- til 2001 for the purpose: turing plant at Pargny-sur-Saulx, revealed that • geographical study of mortality2; from 1934 to the beginning of the 1970s, signif- • control case studies3; icant amounts of imported monazite ore, rich in • radiotoxicological analyses. natural radioactive elements, particularly tho- The epidemiological studies were carried out in rium-232, with a half-life of 14 billion years had conjunction with INSERM’s U521 unit (geo- been handled. At that time, Orflam-Plast chemi- graphical study of mortality) and the health References cally extracted the ore, cerium, a hard metal used watchdog Institute InVS (control case survey). 1 - “Société Orflam- for making lighter flints. The residual waste of IRSN’s in-house mass spectrometry thorium Plast à Pargny-sur- Saulx: expertise this manufacturing process was in solid form measuring facilities were used to carry out urine des conséquences made up of mineral sand with high thorium con- analyses for radiotoxicity. sanitaires par l’OPRI”, internal tent. The several thousand metric tons of mon- OPRI report, 1997. azite handled in this plant thus led to an initial Geographical study of mortality 2 - F. de Vathaire, C. Challeton de approximation of an almost equivalent amount of Vathaire, J. Ropers, waste. Apparently no precautions were taken An audit carried out by IRSN in 1997, demon- A. Mollié, “Cancer Mortality in the when spreading this ore residue whose radioele- strated that the former employees and neigh- Commune of Pargny-sur-Saulx in ment content was ignored or unknown in the boring population were likely to have been France”, J. Radiol. environment. It was found scattered on the very exposed to ionizing radiation at levels consider- Prot, 18, 23-27, 1998. site of the company and in particular, in the ably higher than naturally occurring radioactivity 3 - C. Challeton de premises where the ore was handled in bulk1. levels, the dose rate occasionally peaking at Vathaire, P. Quenel, A. Zeghnoun, About 7500 metric tons of this residue was used 10 µSv/h, that is over 100 times the natural J.-H. Leblanc, “Étude to build an embankment several hundred meters ambient level1. These estimates, based on the cas-témoins de mortalité par cancer along the River Saulx, both upstream and down- measurements made in the defunct manufactur- du poumon et de la vessie, Pagny-sur- stream of where it crossed the plant site; the ing environment, did not enable any conclusions Saulx, Marne, 1986- residue was thus “put to use” protecting the to be drawn on earlier potential exposure. 1996”, internal OPRI report, June 2000. neighboring meadows from winter floods. Moreover it appeared that the majority of SCIENTIFIC AND TECHNICAL REPORT 2002 159 was associated with having worked on the Orflam-Plast site in order to go a step forward. Occupational exposure to This epidemiological study of control cases of cancer mortality at Pargny-sur-Saulx was con- ionizing radiation was cited as ( ducted in conjunction with the Environmental potentially responsible for the Health Department and the Health Watchdog surplus of cancers observed. Institute (InVS) and with the agreement of the French civil liberties organization, the CNIL. The individual data on death consolidated for the period 1968-1996 was supplied by INSERM’s SC8, for people living within a 10 km radius of Pargny-sur-Saulx at the time of death. For this control case mortality study carried out on the general population, the immediate, principal and Orflam-Plast employees likely to have been combined causes of each death were obtained. exposed the most were recruited and lived in the The cases were defined as being individuals districts surrounding Pargny. deceased through lung or bladder cancer in the This led to a study into cancer mortality in con- study area and for the period under considera- junction with INSERM’s U521 unit from data tion. from the national mortality database, managed The control cases were defined as being individ- by INSERM’s joint service 8 (SC8) at Le Vésinet. uals who had died from some other cause in the This study was carried out across all the districts area under study for the study period. They were within a 16 km radius of Pargny, for the period selected from a file of causes of death excluding 1968-1994. It revealed an overshoot of 40% over respiratory ailments and genito-urinary appara- the norm of deaths through lung cancer and tus ailments. Secondly these control cases were bladder cancer in men aged over 40 living in the paired up to the cases by sex, age (in 5-year seg- catchment area at the time of death. Moreover, ments) and the period of occurrence of death. this mortality surplus increased significantly as Three such periods of occurrence of death were the study approached the district of Pargny-sur- Saulx (11 additional cases of lung cancer and 6 additional cases of bladder cancer). Measuring ionizing radiation A precise mortality analysis did not reveal a sur- on the Orflam-Plast plant site. plus of deaths through cancer in the neighboring districts of the Saulx downstream of Pargny. This observation enabled us to rule out the risk of a major health implication that might have resulted from thorium contamination carried by leaching waters. Consequently, the significantly higher than average national mortality rate through lung and bladder cancer registered in male residents of Pargny prompted the search for a one-off possibly occupational origin. This is why occupational exposure to ionizing radiation • was cited as potentially responsible for the sur- plus of cancers observed, and in particular lung cancers, because of the presence of thorium in the dust generated while handling the ore. Control case study It was necessary to test the hypothesis accord- ing to which death through lung or bladder can- cer within a radius of 10 km of Pargny-sur-Saulx 160 INSTITUT DE RADIOPROTECTION ET DE SÛRETÉ NUCLÉAIRE 4 Orflam-Plast site (March 1999). Protection of human life defined, in principle, on the basis of the mortal- izing access to data relating to the death of peo- ity survey findings for the general population: ple registered in the RNIPP in the context of period No. 1, 1968-1977; period No. 2, 1978- research into health”. Eleven of those 46 indi- 1987; period No. 3, 1988-1994. A fourth period viduals were subsequently identified. (1995-1996) was added to draw on the maximum The statistical analysis of the data consisted in possible number of cases. Three paired control comparing the frequency of membership of the cases were associated with each of the other category of former Orflam-Plast employee in the cases by random selection. real and control cases by making a paired analy- The characterization of exposure to thorium was sis (Epi-info software, version 6.04). carried out as follows. Research was made to find out for all the cases and control cases THE FINDINGS selected, whether they had or had not worked at The mortality data for the study between 1968 the Orflam-Plast plant, however long the period and 1996 are as follows: 3501 deaths of which of employment. This research was based on the 879 cancers, broken down into 154 cases of lung register of former Orflam-Plast employees, cancer (142 men and 12 women) and 39 cases held by the Champagne-Ardennes Regional of bladder cancers (27 men and 12 women). The Employment, Work and Professional Training file of former employees of the manufacturing Office (DRTEFP) in the occupational medical site numbered 692 individuals. The proportion of inspection department. The file was compiled female employees was 74%. Of the 641 employ- from occupational medical records (for employ- ees for whom information was available, 380 ees who worked on the site from 1980 onwards), (59%) were hired before 1970. Of the 599 the work inspection register (register of employ- employees for whom information was available, ees hired and leavers) and the register of 434 (72%) were aged under 20 when they were employees covered by redundancy schemes.