Strontium-90 concentration measurements in human bones and teeth in Greece

Migration mechanisms of 90Sr and 137Cs on terraces

In order to investigate the impact of environmental conditions on the distribution and migration of 90Sr in the Longji terrace environment, the activity concentrations of 90Sr and 137Cs were determined. The activity concentration ranges of 90Sr and 137Cs in surface soil were 0.15-1.04 Bq/kg and 2.16-6.94 Bq/kg, respectively. These results showed that there was a similar trend between the activity concentration of 90Sr and 137Cs in the surface soil along the runoff path and their activity concentration were influenced by the slope of the terraced terrain. On the other hand, the activity ranges of 90Sr and 137Cs in soil cores were 0.01-2.74 Bq/kg and 0.43-7.19 Bq/kg, respectively. These results indicate that the migration mechanism of 90Sr is different from that of 137Cs. As compared with 137Cs, 90Sr is significantly influenced by the moisture content. In addition, high span of 137Cs/90Sr activity ratios were found in this study, which were attributed to the characteristics of cultivated land and frequent artificial disturbances that intensified the migration of 90Sr.

Mineral Mimetic Material Sr-Exchanged Sitinakite of Different Crystallinity: Phase Transformations during Heat Treatment and the Strength of SR Fixation in a Ceramic Matrix

A simple method for the direct transformation of Sr-exchanged titanosilicate with the sitinakite structure (IONSIV) into ceramic material through cold pressing and subsequent sintering at 1100 °C for 4 h is presented. The temperature transformation of Sr-exchanged sitinakite showed the stages of recrystallization of the material with the formation of Sr-Ti phases matsubaraite (Sr4Ti5[Si2O7]2O8), jeppeite (SrTi6O13), tausonite (SrTiO3), and rutile. Leaching experiments showed the efficiency of fixation of Sr cations in a ceramic matrix; extraction into water does not exceed 0.01% and desorption in 1 M HNO3 solution is only 0.19% within three days. The leaching rates of immobilized Sr demonstrate the structural integrity of the formed phases in the ceramic (2.8 × 10-5-1.0 × 10-5 g/(m2·day). The decrease in the crystallinity of the initial Na-sitinakite, which is achieved by reducing the synthesis temperature from 250 to 210 °C, does not affect the sorption capacity and the fixation of cations in the ceramic matrix. The obtained results confirm the prospect of using inexpensive precursors, titanium ore enrichment waste, for the synthesis of sorption materials.

Elemental Composition of Commercial Herbal Tea Plants and Respective Infusions

This study evaluated the elemental composition of 25 herbal tea plants commonly used in infusions by Portuguese consumers and the contribution to the elemental daily intake of some essential elements. Hydrocotyle asiatica (L.), Matricaria chamomilla (L.), and Melissa officinalis (L.) samples are a rich source of K with around 6.0 mg g−1 while the Asteraceae Silybum marianum (L.) and Echinacea angustifolia (DC.) exhibited 4.9 and 5.6 mg g−1 Ca, respectively. The highest concentrations of S and Zn were noted in Hydrocotyle asiatica (L.), while the highest concentration of Sr was found in Cassia angustifolia (Vahl.). In general, a large variability in the concentrations among different families and plant organs had been observed, except Cu with levels around 30 μg g−1. The principal component analysis (PCA) showed positive correlations between Zn and S and Sr and Ca, also revealing that Hydrocotyle asiatica (L.), Echinacea angustifolia (DC.), Silybum marianum (L.), and Cassia angustifolia (Vahl.) samples, stands out about all other samples regarding the enrichment of macro and micronutrients. The elemental solubility of macronutrients in the infusion is greater than the micronutrient solubility, despite the contribution to the recommended daily intake was weak. As a whole, Cynara scolymus (L.) and Hibiscus sabdariffa (L.) are the species with the best elemental solubilities, followed by Hydrocotyle asiatica (L.). No harmful elements, such as As and Pb, were observed in both the raw material and the infusions.

Elemental Composition of Algae-Based Supplements by Energy Dispersive X-ray Fluorescence

The aim of this study is to evaluate the elemental composition of fifteen algae-based supplements commonly sold in the Portuguese market, by energy dispersive X-ray fluorescence. Despite the fact that the majority of Kelp samples were a good source of iodine, the levels observed might well contribute to an excess in the human body, which can cause dysfunction of the thyroid gland. Furthermore, the presence of lead in Sea spaghetti, Arame, Hijiki and Wakame caused a considerable risk to public health vis a vis possible ingestion of a high daily dose. Regarding arsenic, great variability was observed in all the samples with concentrations equal to or above 60 μg/g in the case of Arame, KelpJ and Hijiki. Although algae mainly accumulate organic arsenic, some also contain high levels of its inorganic form, as is commonly pointed out for Hijiki. Thus, regular ingestion of these supplements must also take into account the mentioned facts. There is no doubt that these supplements are also good sources of other nutrients, but the lack of accurate regulations and control should alert consumers to avoid indiscriminate use of these types of products.

Radioactivity and radionuclides in deciduous teeth formed before the Fukushima-Daiichi Nuclear Power Plant accident

The Fukushima-Daiichi Nuclear Power Plant (FNPP) accident in March of 2011 released substantial amounts of radionuclides into the environment. We collected 4,957 deciduous teeth formed in children before the Fukushima accident to obtain precise control data for teeth formed after the accident. Radioactivity was measured using imaging plates (IP) and epidemiologically assessed using multivariate regression analysis. Additionally, we measured ⁹⁰Sr, ¹³⁷Cs, and natural radionuclides which might be present in teeth. Epidemiological studies of IP showed that the amount of radioactivity in teeth from Fukushima prefecture was similar to that from reference prefectures. We found that artificial radionuclides of ⁹⁰Sr and ¹³⁷Cs, which were believed to have originated from past nuclear disasters, and natural radionuclides including ⁴⁰ K and daughter nuclides in the ²³⁸U and ²³²Th series contributed to the generation of radioactivity in teeth. We also found no evidence to suggest that radionuclides originating from the FNPP accident significantly contaminated pre-existing teeth. This is the first large-scale investigation of radioactivity and radionuclides in teeth. The present findings will be indispensable for future studies of teeth formed after the FNPP accident, which will fall out over the next several years and might be more contaminated with radionuclides.

Activity of 90Sr in Fallout Particles Collected in the Difficult-to-Return Zone around the Fukushima Daiichi Nuclear Power Plant

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released abundant radioactive particles into the surrounding environment. Herein, we analyzed the activity of ⁹⁰Sr in these particles to estimate the contribution of this radionuclide to the overall radiation exposure and shed light on the processes that occurred during the accident. Seven radioactive particles were isolated from the dust and soil samples collected from areas surrounding the FDNPP, and the minimum/maximum ¹³⁷Cs activities were determined as 224/4,100 Bq. Based on the size, specific activity, and ¹³⁴Cs/¹³⁷Cs activity ratios, we concluded that six of the seven radioactive particles were released from the Unit 1 reactor, while one particle was released from the Unit 3 reactor by a hydrogen explosion. Strontium-90 was detected in all radioactive particles, and the minimal/maximal ⁹⁰Sr activities were determined as 0.046/1.4 Bq. ¹³⁷Cs/⁹⁰Sr activity ratios above 1000 were observed for all seven particles, that is, compared to ¹³⁷Cs, ⁹⁰Sr had negligible contribution to the overall radiation exposure. The ¹³⁷Cs/⁹⁰Sr activity ratios of the radioactive particles were similar to those of terrestrial environmental samples and were higher for particles released from the Unit 1 reactor than for samples collected from the Unit 1 reactor building, which indicates possibility of additional ⁹⁰Sr-rich contamination after release of the particles.

A review of measurement methodologies and their applications to environmental 90Sr

The high fission yield product ⁹⁰Sr has been released into the environment in large amounts due to nuclear weapon tests, nuclear power plant accidents, and nuclear fuel reprocessing industries. It is a long half-life radionuclide (28.9 y), with serious consequences to human health; hence, it is desirable to perform routine monitoring of ⁹⁰Sr in environmental samples. Many ⁹⁰Sr radiometric methods have been developed in the past decades, which generally require complicated separation and purification steps with a relatively long analytical time. Moreover, some nominally rapid methods usually have high method detection limits, making them unsuitable for the environmental samples with ultra-low ⁹⁰Sr levels. In this review, some rapid and practical methods for ⁹⁰Sr routine monitoring are summarized. Different sample pretreatments and major purification procedures for ⁹⁰Sr developed in recent years, such as variable digestion methods and extraction chromatography using Sr resin or DGA resin, are especially described. Additionally, four conventional and widely used β spectrometric and mass spectrometric methods are demonstrated. Finally, ⁹⁰Sr evaluations focusing on contaminated soil and seawater samples collected after the Fukushima Daiichi Nuclear Power Plant accident, and ⁹⁰Sr application as tracers for environmental behavior are also reviewed.

Atmospheric Activity Concentration of 90Sr and 137Cs after the Fukushima Daiichi Nuclear Accident

On March 11, 2011, the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident occurred and large amounts of radionuclides were discharged into the atmosphere. We have operated continuous aerosol samplings at four locations in Japan from the accident until the end of 2011. The activities of ⁹⁰Sr and ¹³⁷Cs in the aerosol samples were measured using low background liquid scintillation counters and high-purity germanium detectors, respectively. The atmospheric ⁹⁰Sr and ¹³⁷Cs concentrations decreased exponentially during 2011. The time variation of the ⁹⁰Sr/¹³⁷Cs ratio was obtained, and we found that the ratio rose from 1.2 × 10^-3 in March to 1.3 × 10^-1 in August 2011. One reason for the increase in the ⁹⁰Sr/¹³⁷Cs ratio could be the change in the primary emission source of activity at the FDNPP, which occurred near June 2011.

(90)Sr in teeth of cattle abandoned in evacuation zone: Record of pollution from the Fukushima-Daiichi Nuclear Power Plant accident

Here we determined the ⁹⁰Sr concentrations in the teeth of cattle abandoned in the evacuation area of the Fukushima-Daiichi Nuclear Power Plant (FNPP) accident. ⁹⁰Sr activity concentrations in the teeth varied from 6–831 mBq (g Ca)⁻¹ and exhibited a positive relationship with the degree of radioactive contamination that the cattle experienced. Even within an individual animal, the specific activity of ⁹⁰Sr (Bq (g Sr)⁻¹) varied depending on the development stage of the teeth during the FNPP accident: teeth that were early in development exhibited high ⁹⁰Sr specific activities, while teeth that were late in development exhibited low specific activities. These findings demonstrate that ⁹⁰Sr is incorporated into the teeth during tooth development; thus, tooth ⁹⁰Sr activity concentrations reflect environmental ⁹⁰Sr levels during tooth formation. Assessment of ⁹⁰Sr in teeth could provide useful information about internal exposure to ⁹⁰Sr radiation and allow for the measurement of time-course changes in the degree of environmental ⁹⁰Sr pollution.

Determination of radionuclides in samples of middle-aged and older human femurs

The paper presents the studies of the presence of gamma isotopes and (90)Sr in 19 middle-to old-aged human femur samples. The samples were taken up during routine orthopedic operations in 2012. The aim of the paper was determination of some radionuclides in human bones and estimation of radiation dose created by (90)Sr and (90)Y (in bones). The (137)Cs, (40)K, (226)Ra, (228)Th, (234)Th and (210)Pb isotopes were determined by gamma spectrometry. The above mentioned radionuclide contents were in the ranges: (137)Cs (0.04-1.45); (40)K (13-86); (226)Ra (1-21.5); (228)Th (1.4-40.2); (234)Th (0.4-5.7); (210)Pb (0.7-8.4) Bq/kg d.w. (90)Sr was assayed based on radiometric measurement of ingrown (90)Y. The (90)Sr content was in the range 0.27-1.85 Bq/kg d.w. Measurements of concentration of (90)Sr and (90)Y in bones were used to estimation of health risk by calculation of radiation dose. Adsorbed doses ranged from 2.7 · 10(-7) to 1.9 · 10(-6) Gy/y for (90)Sr and from 1.2 · 10(-6) to 8.3 · 10(-7) Gy/y for (90)Y.

Importance of laser-induced breakdown spectroscopy for hard tissues (bone, teeth) and other calcified tissue materials

Laser-induced breakdown spectroscopy (LIBS) as a sensitive optical technique capable of fast multielemental analysis proved to be a versatile tool in different applications. It became visible in the analytical atomic spectroscopy scene in the late 1980s and since then, its applications having been developed continuously in different field of science and technology including biomedical science. Here, we review the use and importance of LIBS for trace element determination in different calcified tissue materials. In this article, we have also reported a comprehensive review of the recent progress of biomedical applications of LIBS.

LIBS analysis of artificial calcified tissues matrices

In most laser-based analytical methods, the reproducibility of quantitative measurements strongly depends on maintaining uniform and stable experimental conditions. For LIBS analysis this means that for accurate estimation of elemental concentration, using the calibration curves obtained from reference samples, the plasma parameters have to be kept as constant as possible. In addition, calcified tissues such as bone are normally less "tough" in their texture than many samples, especially metals. Thus, the ablation process could change the sample morphological features rapidly, and result in poor reproducibility statistics. In the present work, three artificial reference sample sets have been fabricated. These samples represent three different calcium based matrices, CaCO3 matrix, bone ash matrix and Ca hydroxyapatite matrix. A comparative study of UV (266 nm) and IR (1064 nm) LIBS for these three sets of samples has been performed under similar experimental conditions for the two systems (laser energy, spot size, repetition rate, irradiance, etc.) to examine the wavelength effect. The analytical results demonstrated that UV-LIBS has improved reproducibility, precision, stable plasma conditions, better linear fitting, and the reduction of matrix effects. Bone ash could be used as a suitable standard reference material for calcified tissue calibration using LIBS with a 266 nm excitation wavelength.

A strontium-90 sequestrant for first-aid treatment of radiation emergency

In this study, hydrophilic porous polymer beads with phosphonic acid groups (PGMA-EGDMA-TTA-MP) were synthesized, and assessed as a radioactive strontium-90 sequestrant for the treatment of the radiation emergency. Strontium ions were rapidly absorbed into the blood from the gastrointestinal (GI) tract after oral administration to rats, and distributed to the target organ, i.e., bones. Over 40% of the administered strontium was absorbed into the blood, while the remainder was discharged in the feces within 48 h after the administration. When the PGMA-EGDMA-TTA-MP beads were administered to rats subsequent to the strontium solution, the strontium had accumulated less in the femur. Consequently, the oral administration of the PGMA-EGDMA-TTA-MP beads was effective in suppressing the absorption of strontium from the GI tract.

Elevated in vivo strontium-90 from nuclear weapons test fallout among cancer decedents: a case-control study of deciduous teeth

Risks to health from large-scale atmospheric nuclear weapons testing are still relatively unknown. A sample of 85,000 deciduous teeth collected from Americans born during the bomb-testing years assessed risk by in vivo measurement of residual strontium-90 (Sr-90) concentrations, using liquid scintillation spectrometry. The authors' analysis included 97 deciduous teeth from persons born between 1959 and 1961 who were diagrosed with cancer, and 194 teeth of matched controls. Average Sr-90 in teeth of persons who died of cancer was significantly greater than for controls (OR = 2.22; p < 0.04). This discovery suggests that many thousands have died or will die of cancer due to exposure to fallout, far more than previously believed.

Biomaterials for the decorporation of (85)Sr in the rat

Although four stable isotopes of strontium occur naturally, Sr is produced by nuclear fission and is present in surface soil around the world as a result of fallout from atmospheric nuclear weapons tests. It can easily transfer to humans in the event of a nuclear/radiological emergency or through the plant-animal-human food chain causing long-term exposures. Strontium is chemically and biologically similar to calcium, and is incorporated primarily into bone following internal deposition. Alginic acid (alginate) obtained from seaweed (kelp) extract selectively binds ingested strontium in the gastrointestinal tract blocking its systemic uptake and reducing distribution to bone in rats, while other natural polysaccharides including chitosan and hyaluronic acid had little in vivo affinity for strontium. Alginate exhibits the unique ability to discriminate between strontium and calcium and has been previously shown to reduce intestinal absorption and skeletal retention of strontium without changing calcium metabolism. In our studies, the effect of commercially available alginate on intestinal absorption of strontium was examined. One problem associated with alginate treatment is its limited solubility and gel formation in water. The aqueous solubility of sodium alginate was improved in a sodium chloride/sodium bicarbonate electrolyte solution containing low molecular weight polyethylene glycol (PEG). Furthermore, oral administration of the combined alginate/electrolyte/PEG solution accelerated removal of internal strontium in rats when compared to treatment with individual sodium alginate/electrolyte or electrolyte/PEG solutions. Importantly, both alginate and PEG are nontoxic, readily available materials that can be easily administered orally in case of a national emergency when potentially large numbers of the population may require medical treatment for internal depositions. Our results suggest further studies to optimize in vivo decorporation performance of engineered alginate material via modification of its chemical and physicochemical properties are warranted.

Retention half times in the skeleton of plutonium and 90Sr from above-ground nuclear tests: a retrospective study of the Swiss population

Plutonium and (90)Sr are considered to be among the most radiotoxic nuclides produced by the nuclear fission process. In spite of numerous studies on mammals and humans there is still no general agreement on the retention half time of both radionuclides in the skeleton in the general population. Here we determined plutonium and (90)Sr in human vertebrae in individuals deceased between 1960 and 2004 in Switzerland. Plutonium was measured by sensitive SF-ICP-MS techniques and (90)Sr by radiometric methods. We compared our results to the ones obtained for other environmental compartments to reveal the retention half time of NBT fallout (239)Pu and (90)Sr in trabecular bones of the Swiss population. Results show that plutonium has a retention half time of 40+/-14 years. In contrast (90)Sr has a shorter retention half time of 13.5+/-1.0 years. Moreover (90)Sr retention half time in vertebrae is shown to be linked to the retention half time in food and other environmental compartments. These findings demonstrate that the renewal of the vertebrae through calcium homeostatic control is faster for (90)Sr excretion than for plutonium excretion. The precise determination of the retention half time of plutonium in the skeleton will improve the biokinetic model of plutonium metabolism in humans.

Temporal trends in childhood leukaemia incidence following exposure to radioactive fallout from atmospheric nuclear weapons testing

Notably raised rates of childhood leukaemia incidence have been found near some nuclear installations, in particular Sellafield and Dounreay in the United Kingdom, but risk assessments have concluded that the radiation doses estimated to have been received by children or in utero as a result of operations at these installations are much too small to account for the reported increases in incidence. This has led to speculation that the risk of childhood leukaemia arising from internal exposure to radiation following the intake of radioactive material released from nuclear facilities has been substantially underestimated. The radionuclides discharged from many nuclear installations are similar to those released into the global environment by atmospheric nuclear weapons testing, which was at its height in the late-1950s and early-1960s. Measurements of anthropogenic radionuclides in members of the general public resident in the vicinity of Sellafield and Dounreay have found levels that do not differ greatly from those in persons living remote from nuclear installations that are due to ubiquitous exposure to the radioactive debris of nuclear weapons testing. Therefore, if the leukaemia risk to children resulting from deposition within the body of radioactive material discharged from nuclear facilities has been grossly underestimated, then a pronounced excess of childhood leukaemia would have been expected as a consequence of the short period of intense atmospheric weapons testing. We have examined childhood leukaemia incidence in 11 large-scale cancer registries in three continents for which data were available at least as early as 1962. We found no evidence of a wave of excess cases corresponding to the peak of radioactive fallout from atmospheric weapons testing. The absence of a discernible increase in the incidence of childhood leukaemia following the period of maximum exposure to the radioactive debris of this testing weighs heavily against the suggestion that conventional methods are seriously in error when assessing the risk of childhood leukaemia from exposure to man-made radionuclides released from nuclear installations.

Monte Carlo-based calculation of imaging plate response to (90)Sr in teeth: experimental validation of the required correction on sample thickness

Recently, a numerical method was proposed to correct the imaging plate (IP) response to (90)Sr concentration in tooth samples, depending on the sample thickness. This is important to quantify any (90)Sr concentration in teeth, which in turn is necessary to determine any (90)Sr incorporation of a person retrospectively. Although the final goal will be to evaluate the (inhomogeneous) spatial distribution of (90)Sr inside tooth samples precisely, the present study was restricted -- as a first step -- to the evaluation of (90)Sr in teeth assuming a uniform (90)Sr distribution. A numerical method proposed earlier was validated experimentally in the present study by measuring the IP response to standard sources of various thicknesses and (90)Sr concentrations. For comparison, the energy deposition of the beta-rays emitted by (90)Sr in the IP -- which is considered to be proportional to the IP luminescence signal -- was calculated for the various sample thicknesses involved, by means of the MCNP-4C code. As a result, the measured IP response could be reproduced by the calculations within the uncertainties, depending on the thickness of the standard sources. Thus, the validity of the proposed numerical method to correct the IP response for sample thickness has successfully been demonstrated.

90Sr in deciduous teeth from 1950 to 2002: the Swiss experience

Switzerland has recorded the level of activity of 90Sr in the milk teeth of children from different regions of the country since the first atomic explosions in the atmosphere. Activity peaked at 0.421 Bq g-1 Ca at the beginning of the sixties, coinciding with the detonation of many large nuclear devices. Following the Nuclear Test Ban Treaty that ended atmospheric nuclear weapon tests, a steady and significant decrease in 90Sr activity in milk teeth has been observed-down to a value of 0.03 Bq g-1 Ca for children born in 1994. The apparent half-life of 90Sr in milk teeth is 9.8+/-3 years. With the exception of the period from 1962 to 1964, there is no correlation between the activity in the teeth of children born in a given year and the year of extraction. Between 1953 and 1992, the milk teeth of children born in Zürich county showed 16% less activity than teeth from children born in Vaud county. Dairy consumption habits might be responsible for this trend. The effect of the 90Sr deposition from Chernobyl is barely measurable in milk teeth, and no effect is seen from the five Swiss nuclear reactors. This paper emphasizes the necessity of a very high purity chemical separation of 90Sr or 90Y to determine 90Sr activity in milk teeth or other samples.

Trace elements and butyltins in a Dall's porpoise (Phocoenoides dalli) from the Sanriku coast of Japan

Concentrations and body burdens of 14 trace elements (Hg, Cr, Mn, Co, Cu, Zn, Sr, Ag, Cd, V, Se, Pb, Mo, and Fe) and butyltins (BTs) (tributyltin TBT, dibutyltin DBT, and monobutyltin MBT) were determined in various tissues of a mature male Dall's porpoise (Phocoenoides dalli) collected off the Sanriku coast of Japan. Selective accumulation in this porpoise was observed for Hg, Mn, Cu, Ag, Mo, Fe, and total BTs (TBT, DBT, and MBT) in the liver, Cd in the kidney, Zn, Sr, V, Pb, and Co in the bone, and Se in the skin. In contrast, Cr concentrations in all tissues were similar. This distribution pattern in this mature porpoise was in general agreement with the accumulation characteristics of trace elements and butyltins reported for other marine mammals. The whole body of the porpoise contained approximately 62 g Fe, 8.8 g Zn, 4.0 g Sr, 0.6g Se, 0.41 g Cu, 0.19 g Hg, 0.17 g Cd, 0.16 g Mn, 0.05 g Cr, 0.009 g Ag, 0.008 g Mo, 0.005 g Pb, 0.004 g Co, and 0.7 mg of BTs (0.4 mg TBT, 0.2 mg DBT, and 0.1 mg MBT). Metabolism of TBT to its breakdown products of this porpoise seems to be limited, since TBT still accounted for about half of the total burden of BTs. As in the cases of Hg, Mn, Cu, Se, and Fe, the muscle was the most important reservoir (43%) for the whole body burden of total BTs, 80% of which was TBT, and thus muscle played a crucial role in the higher body composition of TBT in this Dall's porpoise.

Difficulty in dislodging in vivo fixed radiostrontium

Many trials based on the basic phenomena of isotopic dilution, adsorption, ion exchange, chelation, etc., have been attempted for the decorporation of radiostrontium, particularly Sr, after its entry in the in vivo system. We have recently demonstrated a non-isotopic carrier effect of some common calcium salts (calcium = 9 mg mL) to reduce the whole body retention of radiostrontium, if administered within 2 h after radiostrontium exposure and furthermore once daily, in rats, supplemented with calcium fortified diet. However, 25-30% of radiostrontium (compared to 50-60% in untreated animals) was still found to be retained in the animal even after 2 wk of treatment. Trial of some simple interventional measures, which would not adversely affect the animal metabolism, like pyrophosphate and magnesium sulfate, sodium citrate, chitin (a bio-absorbent), crown ether (a metal-chelator), and ammonium chloride, was therefore attempted to dislodge this remaining radiostrontium by switching over these animals to normal diet and subjecting them to different lines of treatment with these simple interventions through diet and drinking water separately for a further 4 wk. However, this remaining portion of radiostrontium is fixed in the bone and is difficult to dislodge.

An unexpected rise in strontium-90 in US deciduous teeth in the 1990s

For several decades, the United States has been without an ongoing program measuring levels of fission products in the body. Strontium-90 (Sr-90) concentrations in 2089 deciduous (baby) teeth, mostly from persons living near nuclear power reactors, reveal that average levels rose 48.5% for persons born in the late 1990s compared to those born in the late 1980s. This trend represents the first sustained increase since the early 1960s, before atmospheric weapons tests were banned. The trend was consistent for each of the five states for which at least 130 teeth are available. The highest averages were found in southeastern Pennsylvania, and the lowest in California (San Francisco and Sacramento), neither of which is near an operating nuclear reactor. In each state studied, the average Sr-90 concentration is highest in counties situated closest to nuclear reactors. It is likely that, 40 years after large-scale atmospheric atomic bomb tests ended, much of the current in-body radioactivity represents nuclear reactor emissions.

Trace elements in skin of Dall's porpoises (Phocoenoides dalli) from the northern waters of Japan: an evaluation for utilization as non-lethal tracers

Concentrations of Fe, Zn, Cu, Se, Mn, Mo, Hg, Cd, Cr, Ag, Pb, Sr and V were determined in skins of Dall's porpoises (Phocoenoides dali) of the Pacific coast truei-type population (PT population) (N = 45), and the Sea of Japan-Okhotsk dalli-type population (JD population) (N = 31) from the northern waters of Japan. Cutaneous Hg concentrations in both PT and JD populations were significantly correlated with age, indicating a possible alternative method of age estimation. A significant correlation was also noted between Hg concentrations in skin and liver, suggesting that biopsy samples of skin can provide a non-lethal surrogate for monitoring Hg contamination in this species. Trace element accumulation patterns differed strongly between PT and JD populations, when analyzed by principal component analysis, suggesting these patterns could be utilized as non-lethal tracers of population identification.