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CONSEQUENCES TO LUNG AND BONE OF EXPOSURE TO ACTINIDES

Objectif


The synergistic effects of cigarette smoke in the induction of lung tumours by inhaled plutonium-239 oxide have been studied. The distribution and effects of alpha and beta emitting radionuclides on the bone and the bone marrow have also been investigated.

The aims of the project were: to complete the study started under a previous contract to compare the incidence of lung tumours in plutonium exposed CBA/H mice which had received one year's exposure to cigarette smoke with that in animals which were either sham-exposed to smoke or were given no treatment other than their initial exposure to plutonium; to initiate further studies designed to determine the effects of tobacco smoke inhalation by mice on plutonium induced lung tumours.

The incidence of lung tumours in plutonium exposed CBA/H mice, which had received 1 year's exposure to cigarette smoke, was compared with that in animals which were either sham exposed to smoke or were given no treatment other than their initial exposure to plutonium. Further studies were also designed to determine the effects of tobacco smoke inhalation by mice on plutonium induced lung tumours.
WORKERS IN THE NUCLEAR INDUSTRY ARE POTENTIALLY EXPOSED TO AIRBORNE 239PUO2 AND OTHER ALPHA-EMITTERS AND, SINCE MANY OF THESE WORKERS ARE CIGARETTE SMOKERS, IT IS IMPORTANT TO INVESTIGATE THE COMBINED EFFECTS OF THESE TWO CARCINOGENS. OF PARTICULAR IMPORTANCE IS WHETHER THE INTERACTION IS ADDITIVE, IN WHICH CASE THE EXCESS TUMOUR INCIDENCE WOULD BE THE SUM OF THE TWO MATERIALS ADMINISTERED INDEPENDENTLY, OR MULTIPLICATIVE, WITH AN EXCESS TUMOUR INCIDENCE WHICH GREATLY EXCEEDS THAT PREDICTED BY THE ADDITIVE MODEL.

THE WORK REPRESENTS THE CONTINUATION OF A 2-YEAR CONTRACT DEALING WITH THE COMBINED EFFECTS OF EXPOSURE TO 239PUO2 AND CIGARETTE SMOKE. IN THE FIRST STUDY 216 FEMALE CBA/H MICE WERE EXPOSED (NOSE ONLY) TO AN AEROSOL OF 239PUO2 WITH AN AMAD OF 1.5 MICRONS AND OG OF 1.3. EACH ANIMAL WAS APPROXIMATELY 10 WEEKS OF AGE AT INHALATION AND RECEIVED AN INITIAL ALVEOLAR DEPOSIT (IAD) OF ABOUT 100 BQ OF 239PU. AT 8 DAYS AFTER INHALATION, THE 241 AM CONTENT OF THE ANIMALS WAS MEASURED BY COUNTING IN-VIVO TO DETERMINE INDIVIDUAL IADS. 241AM IS A MINOR RADIOACTIVE CONTAMINANT OF 239PU. ON THE BASIS OF THESE COUNTS THE ANIMALS WERE DIVIDED INTO MATCHED CAGE GROUPS AND EACH CAGE WAS ALLOCATED RANDOMLY TO ONE OF THREE TREATMENT GROUPS. ONE GROUP, DESIGNATED PTS, WAS EXPOSED TO TOBACCO SMOKE FOR A PERIOD OF ONE YEAR. EACH ANIMAL RECEIVED TOBACCO SMOKE AT A CONCENTRATION OF CA. 1.3 MG/1 OF TAR PARTICULATE MATERIAL FOR ONE HOUR PER DAY, FIVE DAYS PER WEEK, FOR 1 YEAR. A SECOND GROUP, DESIGNATED PSS, WAS SHAM-EXPOSED ACCORDING TO THE PROTOCOL DESCRIBED FOR PTS. THE THIRD GROUP RECEIVED NO FURTHER TREATMENT AND WAS ALLOCATED TO THE CAGE CONTROL (PCC) GROUP.

AS THE EXPOSURES TO CIGARETTE SMOKE STARTED IN OCTOBER 1985, ANIMALS WILL BE KILLED STARTING IN APRIL 1987. IT FOLLOWS THAT, AT THE PRESENT TIME, IT IS NOT POSSIBLE TO ANTICIPATE THE RESULTS OF THE EXPERIMENT. HOWEVER, THE RESULTS OF AN EARLIER STUDY (COMPLETED AS PART OF A PREVIOUS CEC CONTRACT BIO-D-568-84-UK) OF THE INCIDENCE OF TUMOURS IN ANIMALS EXPOSED TO 239PU ONLY, SUGGESTS THAT AN IAD OF ABOUT 100 BQ, A TUMOUR INCIDENCE OF ABOUT 40 % IS OBTAINED COMPARED TO A CONTROL INCIDENCE OF 10-20 %. A MORE DETAILED HISTOPATHOLOGICAL EXAMINATION OF THESE ANIMALS IS CURRENTLY BEING UNDERTAKEN. IF REPRODUCED IN THE CONTROL ANIMALS OF THE PRESENT STUDY, THIS LEVEL WOULD BE IDEAL FOR THE DEMONSTRATION OF ANY SYNGERGISM BETWEEN THE EFFECTS OF 239PUO2 AND CIGARETTE SMOKE.

THE STUDY OF THE DISTRIBUTION OF PLUTONIUM AND AMERICIUM IN THE BONES OF BABOONS IS A CONTINUATION OF A STUDY INITIATED AT THE NATIONAL RADIOLOGICAL PROTECTION BOARD, CHILTON, AND USES CONTAMINATED BABOON BONES PROVIDED BY THE CEA. THESE ARE STUDIED BY AUTORADIOGRAPHY AND THE DISTRIBUTION OF THE RADIONUCLIDES IN BABOONS OF VARIOUS AGES IS DETERMINED FOLLOWING DIFFERENT TYPES OF RADIONUCLIDE INTAKE. THE BONES PROVIDED ARE FROM ANIMALS CONTAMINATED BY EITHER PLUTONIUM-238, PLUTONIUM-239, OR AMERICIUM-241. VARIOUS METHODS OF ADMINISTRATION WERE USED INCLUDING INTRAVENOUS OR INTRAMUSCULAR INJECTION, INGESTION AND INHALATION. THE RADIONUCLIDES WERE ADMINISTRATED IN VARIOUS CHEMICAL FORMS INCLUDING CITRATE, TBP COMPLEXES AND DIOXIDES. TO DATE, THE BONES OF 35 BABOONS HAVE BEEN RECEIVED AND ANALYSED.
BONES OF ADDITIONAL BABOONS WILL BE USED TO PRODUCE AGE-DEPENDENT BONE DOSIMETRIC MODELS FOR MAN. PARTICULAR IMPORTANCE WILL BE PLACED ON DETERMINING CHANGES IN THE DISTRIBUTION OF RADIONUCLIDES IN BONE WITH TIME AFTER INTAKE AND ON EXAMINING THE AMOUNT OF ACTIVITY ACCUMULATED BY THE BONE MARROW.

Thème(s)

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Appel à propositions

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Régime de financement

CSC - Cost-sharing contracts

Coordinateur

United Kingdom Atomic Energy Authority (UKAEA)
Contribution de l’UE
Aucune donnée
Adresse
11 Charles II Street
SW1Y 4QP London
Royaume-Uni

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