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Radioactive artifacts: historical sources of modern radium contamination.

Radium has been distributed in a wide variety of devices during the early part of this century. Antique objects containing significant amounts of radium turn up at flea markets, antique shows, and antique dealers, in a variety of locations. These objects include radium in devices which were used by legitimate medical practitioners for legitimate medical purposes such as therapy, as well as a wide variety of "quack cures." These devices may contain anywhere from a few nanocuries to as much as several hundred microcuries of radium. In addition to medical sources, a large variety of scientific instruments utilize radium in luminous dials. These instruments include compasses, azimuth indicators, and virtually any object which might require some form of calibration. In addition, the consumer market utilized a large amount of radium in the production of wrist watches, pocket watches, and clocks with luminous dials. Some of these watches contained as much as 4.5 microCi of radium, and between 1913 and 1920 about 70 gm was produced for the manufacture of luminous compounds. In addition to the large amount of radium produced for scientific and consumer utilization, there were a number of materials produced which were claimed to contain radium but in fact did not, further adding to the confusion in this area. The wide availability of radium is a result of the public's great fascination with radioactivity during the early part of this century and a belief in its curative properties. A number of objects were produced in order to trap the emanations of radium in water for persons to drink in order to benefit from their healing effects. Since the late 20s and early 30s the public's attitude towards radiation has shifted 180 degrees and it is now considered an extremely dangerous and harmful material. However, even as late as the 1950s, there were still some items produced containing radioactivity which today would be unthinkable. The "Buck Rogers Mystery Ring" of the 1950s was activated with polonium. With the shift in public attitudes towards radioactivity, and increasing problems in disposal of radioactive materials, the disposal of radium presents a particularly perplexing problem. The radium which was produced in the early part of the century is still around in various forms and is extremely difficult to dispose of. All objects discovered claiming to contain radium should be taken seriously and should be properly surveyed.(ABSTRACT TRUNCATED AT 400 WORDS)

Equipment and Supplies↗

Contamination of settling ponds and rivers as a result of discharge of radium-bearing waters from Polish coal mines.

Saline waters from underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from the uranium decay series and 228Ra from the thorium series. Approximately 40% of the total amount of radium remains underground as radioactive deposits, but 225 MBq of 226Ra and 400 MBq of 228Ra are released daily into the rivers along with the other mine effluents from all Polish coal mines. Technical measures such as inducing the precipitation of radium in gobs, decreasing the amount of meteoric inflow water into underground workings, etc. have been undertaken in several coal mines, and as a result of these measures, the total amount of radium released to the surface waters has diminished by about 60% during the last 5-6 years. Mine water can have a severe impact on the natural environment, mainly due to its salinity. However, associated high levels of radium concentration in river waters, bottom sediments and vegetation have also been observed. Sometimes radium concentrations in rivers exceed 0.7 kBq/m3, which is the permitted level for waste waters under Polish law. The extensive investigations described here were carried out for all coal mines and on this basis the total radium balance in the effluents has been calculated. Measurements in the vicinity of mine settling ponds and in rivers have given us an opportunity to study radium behaviour in river waters and to assess the degree of contamination. Solid waste materials with enhanced natural radioactivity have been produced in huge amounts in the power and coal industries in Poland. As a result of the combustion of coal in power plants, low-radioactive waste materials are produced, with 226Ra concentration seldom exceeding a few hundreds of Bq/kg. A different situation is observed in coal mines, where, as a result of precipitation of radium from radium-bearing waters, highly radioactive deposits are formed. Sometimes the radioactivity of such materials is extremely high; precipitates from coal mines may have radium concentrations of 400,000 Bq/kg--equivalent to 3% uranium ore. Usually, such deposition takes place underground, but sometimes co-precipitation of radium with barium takes place on the surface, in settling ponds and in rivers. Therefore management of solid waste with technologically enhanced natural radioactivity (TENR) is a very important subject.

Geologic Sediments↗

Mortality from cancers of major sites in female radium dial workers.

The female radium dial workers have now experienced significant mortality from cancers other than the bone sarcomas and head carcinomas long known to be radium induced. The relationships of radium exposure to mortality from cancers of the stomach, pancreas, colon, rectum, liver, lung, breast, cervix, and corpus uteri, and from leukemia were studied in 1,285 pre-1930 dial workers. Mortality was compared with that expected from rates for US white females, with and without adjustment for local area mortality rates, and with mortality in dial workers exposed from 1930 to 1949. For the 693 cases whose body content of radium has been measured since 1955, dose-response relationships of cancer to systemic intake of radium and duration of employment were examined. Liver, pancreatic, cervical, and uterine cancers were clearly unrelated to radium exposure. Other cancers of the digestive tract appeared to be indirectly, if at all, associated with work in radium facilities. Lung cancer requires further investigation; inhalation exposures of the dial workers were reviewed. Analyses of the breast cancer data uncovered several observations inconsistent with the previously suggested causal association with radium exposure. Multiple myeloma was also reviewed. A threefold excess risk of death due to multiple myeloma has occurred, but is more closely correlated with duration of employment (a surrogate for external gamma radiation) than with radium intake.

Aged↗

Low-level radium retention by the human body: a modification of the ICRP publication 20 retention equation.

Recently published rates of elimination of radium (in percentage of contemporary body content per year) demonstrated that human radium cases with low body contents lost radium more rapidly than predicted by the ICRP Publication 20 retention equation. In ICRP Publication 20, the apposition and resorption rate in compact bone is defined as 2.5% y-1, but in the derivation of the retention equation for radium a value of only 1.5% y-1 was used. In the present work, the retention equation was reevaluated by using the rate of 2.5% y-1. The revised equation was a good fit to the data for measured values of the body content of radium from environmental levels of radium in food and water. The equation also described the observed rate of loss of radium at long times after deposition for radium cases with low measured body burdens.

Body Burden↗

Geochemical factors controlling radium activity in a sandstone aquifer.

Geochemical processes behind the occurrence of radium activities in excess of the U.S. EPA's drinking water limit of 5 pCi/L combined radium were investigated in a regional sandstone aquifer located in southeastern Wisconsin. Geochemical speciation modeling (PHREEQC 2.7) combined with a detailed understanding of the regional flow system provided by recent flow modeling efforts was used to determine that radium coprecipitation into barite controls radium activity in the unconfined portion of the aquifer. As the aquifer transitions from unconfined to confined conditions, radium levels rise and the water becomes more sulfate rich yet the aquifer remains at saturation with barite throughout. Calculations based on published distribution coefficients and the observed Ra:Ba atomic ratios indicate that barite contains approximately 12 mug/kg coprecipitated radium. Confined portions of the aquifer have high concentrations of sulfate, and barium concentrations become too low to be an effective control on radium activity. Additional, as yet undefined, controls on radium are operative in the downgradient, confined portion of the aquifer.

Radium↗

Radium-contaminated water: a risk factor for cancer of the upper digestive tract.

There is a high incidence of oral, pharynx and esophagus cancer among males in Na Mom district in Songkhla Province in Thailand, an area where radium concentration in shallow well water is found to be higher than other areas in this province. A population-based case control study was conducted from June to November 2004 to determine the association of oral exposure to radium-contaminated water and cancer of the upper digestive tract in the district.Thirty-two confirmed cases and 128 sex and five-year birth cohort matched neighborhood controls were selected by multistage sampling from six villages in four sub-districts. All subjects were verified to have been permanent residents in the district for more than 10 years. Thirty cases were dead at the time of the study, thus their relatives were interviewed to determine their amount of water drinking, tobacco smoking, alcohol drinking, betel chewing and exposure to other potential risk factors in the past. The other two cases and all controls were directly interviewed. The concentration of radium in shallow well water at the subject's houses was estimated using a contour map of Ra-226 in the water at the location of their residence. The results showed a strong and dose-dependent associationb etween consumption of radium-contaminated shallow well water and cancer of the upper digestive tract. In multivariate analysis controlled for important risk factors of the cancer, the odds ratios for exposure to oral radium consumption 50-100 mBq/day and >100 mBq/day compared with <50 mBq/day were 2.83 (95% CI: 0.50-16.19) and 29.76 (95% CI: 4.39-201.6) respectively. The risk also increased with consumption of fresh water fish which might have been contaminated by dissolved radium in the water. This study offers the first evidence of the association between radium and cancer of the upper digestive tract to the world literature. Further studies with other methods such as area-wide correlation of radium-uranium concentration and the incidence of the cancer and case-control studies in other populations are needed to confirm the evidence.

Aged↗

Use of radium isotopes to determine the age and origin of radioactive barite at oil-field production sites.

Radium-bearing barite (radiobarite) is a common constituent of scale and sludge deposits that form in oil-field production equipment. The barite forms as a precipitate from radium-bearing, saline formation water that is pumped to the surface along with oil. Radioactivity levels in some oil-field equipment and in soils contaminated by scale and sludge can be sufficiently high to pose a potential health threat. Accurate determinations of radium isotopes (226Ra + 228Ra) in soils are required to establish the level of soil contamination and the volume of soil that may exceed regulatory limits for total radium content. In this study the radium isotopic data are used to provide estimates of the age of formation of the radiobarite contaminant. Age estimates require that highly insoluble radiobarite approximates a chemically closed system from the time of its formation. Age estimates are based on the decay of short-lived 228Ra (half-life = 5.76 years) compared to 226Ra (half-life = 1600 years). Present activity ratios of 228Ra/226Ra in radiobarite-rich scale or highly contaminated soil are compared to initial ratios at the time of radiobarite precipitation. Initial ratios are estimated by measurements of saline water or recent barite precipitates at the site or by considering a range of probable initial ratios based on reported values in modern oil-field brines. At sites that contain two distinct radiobarite sources of different age, the soils containing mixtures of sources can be identified, and mixing proportions quantified using radium concentration and isotopic data. These uses of radium isotope data provide more description of contamination history and can possibly address liability issues.

Barium Sulfate↗