Thorium and fetal neural tube defects: an epidemiological evidence from large case-control study

Background Thorium is ubiquitous in the environment and its relationship with birth defects is still under discussion. This study aimed to investigate the associations of maternal exposure to thorium with risk of neural tube defects (NTDs) by using a case–control study, as well as the relationship between thorium exposure and the indoor air pollution from coal combustion. Methods This study was conducted in 11 local healthcare hospitals during 2003–2007 in Shanxi and Hebei provinces, China. A total of 774 mothers were included as participants who delivering 263 fetuses with NTDs including 123 with anencephaly, 115 with spina bifida, 18 with encephalocele, and 7 other NTD subtypes (cases), and 511 health fetuses without NTDs (controls). Their hair samples were collected as close as to the occipital posterior scalp, of which those grew from 3 months before to 3 months after conception was cut to measure the thorium concentration by inductively coupled plasma-mass spectrometry. Results We found a higher hair thorium concentration in the total NTD cases with 0.901 (0.588–1.382) ng/g hair [median (inter-quartile range)] than that in the controls with a value of 0.621 (0.334–1.058) ng/g hair. Similar results were found for the three concerned NTD subtypes. Maternal hair thorium concentration above its median of the controls was associated with an increased risk of the total NTDs with an adjusted odds ratio of 1.80 [95% confidence interval (CI), 1.23–2.63)] by adjusting for all confounders. There was obvious dose-response relationship between maternal hair thorium concentration and the risk of total NTDs, as well as their two subtypes (i.e. anencephaly and spina bifida). Maternal hair thorium concentration was positive associated with their exposure level to indoor air pollution from coal combustion during cooking. Conclusions Overall, our findings revealed that maternal periconceptional thorium exposure was associated with the risk of NTDs in North China. Reducing the coal usage in the household cooking activities may decrease maternal thorium exposure level. Graphical abstract

Peralihan Rezim Tektonik: Implikasinya pada Konsentrasi Torium di Mamasa dan Tana Toraja, Sulawesi-Indonesia

ABSTRAK Mamasa dan Tana Toraja secara geografis merupakan bagian dari lengan barat Pulau Sulawesi. Batuan-batuan mafik di daerah tersebut dan sekitarnya memiliki nilai laju radiasi tinggi dan anomali kandungan torium (Th). Penelitian ini bertujuan untuk mengetahui mekanisme tataan tektonik yang berperan dalam peningkatan konsentrasi Th. Enam sampel batuan dianalisis menggunakan analisis petrografi dan geokimia (AAS, ICP-MS, NA, dan XRF), dilengkapi dengan pentarikhan umur menggunakan metode 40K-40Ar pada sampel batuan terpilih. Pengamatan petrografi memperlihatkan kehadiran mineral plagioklas, olivin, piroksen, hornblenda, nefelin, dan alanit pada batuan yang diidentifikasi sebagai nefelin-basanit, basalt, trakhibasalt, dan gabro. Sejumlah tekstur yang tampak pada batuan tersebut mengindikasikan kontaminasi dan perubahan kondisi tektonik. Analisis geokimia menunjukkan bahwa nefelin-basanit, basalt, trakhibasalt, dan gabro (absarokit) terbentuk pada batas kontinental aktif (ACM) yang sedang mengalami transisi dari subduksi aktif (penunjaman ke arah barat) menjadi post-subduksi. Perubahan tataan tektonik membuat magma membeku pada kondisi yang sangat ekstrim. Proses pembekuan magma diinterpretasikan terjadi pada umur sekitar 13,10-11,02 Ma. Mekanisme tersebut berperan penting terhadap terjadinya peningkatan konsentrasi torium di Mamasa dan Tana Toraja.ABSTRACT Mamasa and Tana Toraja geographically are part of the western arm of Sulawesi Island. The mafic rocks in these areas and their surroundings have high radiation dose rate and thorium (Th) anomaly content. This research aim is to determine tectonic setting mechanism which play the important role on the increasing of Th concentration. Six rock samples were analysed using petrography and geochemical analyses (AAS, ICP-MS, NA, and XRF) completed with the 40K-40Ar dating on selected rock samples. Petrography observations show plagioclase, olivine, pyroxene, hornblende, nepheline, and allanite minerals presence in the rocks which identified as nepheline-basanite, basalt, trachybasalt, and gabbro. Numbers of texture appearances in the rocks indicate contamination and changes on tectonic setting. Geochemistry analysis shows that nepheline-basanite, basalt, trachybasalt, and gabbro (absarokite) were formed at the active continental margin (ACM), which is undergoing active subduction (westward subduction) to post-subduction transition. The changing of tectonic setting made magma solidify in extreme conditions. The magma solidify process is interpreted to occur at the age of 13.10-11.02 Ma. These mechanisms play an important role for the increase of thorium concentration in Mamasa and Tana Toraja.

Adsorption of Th(IV) on the modified multi-walled carbon nanotubes using central composite design

Adsorption of thorium onto nitric acid modified multi-walled carbon nanotubes was investigated by central composite design as a function of contact time, pH, initial thorium concentration and temperature. The results showed that optimum uptake capacity was 65.75±2.23 mg·g−1 with respect to pH=4, initial thorium concentration of 100 mg·L−1, 25 °C and 15 min contact time. Thermodynamic parameters [standard enthalpy (ΔH0), entropy (ΔS0), and free energy (ΔG0)] were calculated, and the results indicated that adsorption was endothermic. Langmuir, Freundlich and Dubinin-Radushkevich isotherms have been investigated in order to characterize the adsorption process in the range of 25–100 mg·L−1 initial thorium concentration. The Freundlich isotherm is the best suited as a model because it has the highest correlation coefficient (R2=0.9485). The pseudo-second order kinetics well defined the adsorption process.

In situ high-temperature EXAFS measurements on radioactive and air-sensitive molten salt materials

The development at the Delft University of Technology (TU Delft, The Netherlands) of an experimental set-up dedicated to high-temperature in situ EXAFS measurements of radioactive, air-sensitive and corrosive fluoride salts is reported. A detailed description of the sample containment cell, of the furnace design, and of the measurement geometry allowing simultaneous transmission and fluorescence measurements is given herein. The performance of the equipment is tested with the room-temperature measurement of thorium tetrafluoride, and the Th—F and Th—Th bond distances obtained by fitting of the EXAFS data are compared with the ones extracted from a refinement of neutron diffraction data collected at the PEARL beamline at TU Delft. The adequacy of the sample confinement is checked with a mapping of the thorium concentration profile of molten salt material. Finally, a few selected salt mixtures (LiF:ThF4) = (0.9:0.1), (0.75:0.25), (0.5:0.5) and (NaF:ThF4) = (0.67:0.33), (0.5:0.5) are measured in the molten state. Qualitative trends along the series are discussed, and the experimental data for the (LiF:ThF4) = (0.5:0.5) composition are compared with the EXAFS spectrum generated from molecular dynamics simulations.

Determination of uranium and thorium concentrations in thorium ore sample using artificial neural network and comparison with net area peak method

In order to determine favorable and different elements in soil, the rapid and accurate methods are required. In this research, simultaneous prediction of thorium and uranium in soil samples was performed via gamma spectrometry. Then, the acquired data were analyzed with artificial neural network (ANN) and net area peak (NAP). Natural soil samples obtained from thorium ore consisting of thorium and uranium were used to train models (ANN and NAP). The techniques were evaluated with respect to prediction ability of uranium and thorium concentrations and robustness. Using proposed ANN and NAP methods, the thorium concentration was predicted with mean relative error percentage less than 8.27% and 9.30%, respectively. Also, uranium concentration just was determined with ANN because the NAP method cannot measure uranium concentration. The performance of the neural network model and NAP technique were compared with the acquired empirical data. The results showed that the neural network can more accurately predict the thorium and uranium concentrations in soil samples.

Studi Keterdapatan Torium Pada Endapan Laterit Bauksit di Pulau Singkep Dalam Rangka Pengembangan Eksplorasi Torium di Wilayah Granit Jalur Timah

Eksplorasi torium di wilayah granit jalur timah pada lima tahun terakhir ditargetkan pada keterdapatan torium di cebakan timah primer maupun sekunder. Pulau Singkep adalah bagian dari Granit Jalur Timah, yang potensial terhadap keberadaan torium, sebagai cebakan primer maupun sekunder. Penelitian ini bertujuan untuk mengetahui karakteristik keterdapatan torium pada laterit bauksit menyangkut kadar torium dan kaitannya dengan keterdapatan mineral radioaktif dan kandungan cerium (Ce), lantanum (La), itrium (Y), dan zirkon (Zr) pada laterit bauksit. Data yang diperoleh dari penelitian ini akan digunakan sebagai bahan evaluasi untuk pengembangan eksplorasi torium pada cebakan laterit bauksit di Indonesia. Metode yang digunakan adalah pemetaan geologi, pengukuran kadar torium, dan pengambilan sampel konsentrat dulang untuk analisis mineral butir dan analisis kadar Ce, La, Y, dan Zr. Litologi yang menyusun daerah penelitian terdiri atas granit lapuk yang telah terubah menjadi laterit bauksit dengan kadar torium berkisar antara 25,9 hingga 177,8 ppm eTh. Konsentrat hasil pendulangan adalah konsentrat zirkon-ilmenit dengan kandungan mineral radioaktif terdiri dari zirkon, monasit, dan anatas. Kadar lantanum pada konsentrat zirkon-ilmenit adalah 0–412 ppm, cerium 0–80 ppm, itrium 27–82 ppm, dan zirkon 9.420–100.000 ppm. Keterdapatan torium pada endapan laterit bauksit di Pulau Singkep berhubungan erat dengan keterdapatan mineral zirkon, monasit, dan anatas. Karakterisrik keterdapatan torium pada endapan laterit bauksit mempunyai kemiripan dengan karakteristik keterdapatan torium pada cebakan timah primer dan sekunder. The thorium exploration in the last five years in the granite tin belt region is targeted at thorium availability in primary and secondary tin deposits. Singkep island is the part of granite tin belt which potential for thorium occurences either primer or secondary deposits. The purpose of this study was to determine the characteristics of thorium availability in bauxite laterite deposits concerning thorium content and its relation to the availability of radioactive minerals and cerium (Ce), lanthanum (La), Yttrium (Y), and zircon (Zr) contents on the bauxite laterite deposit. The data obtained from this study will be used as an evaluation material for the development of thorium exploration in bauxite laterite deposits in Indonesia. The methods used are geological mapping, thorium concentration measurements, and sampling of pan concentrate for mineral grain analysis and analysis of Ce, La, Y, and Zr contens. The lithology of the study area was granite that had weathered and turned into bauxite laterite deposit with thorium content ranging from 25.9 to 177.8 ppm eTh. The concentrate of the repeating result is zircon-ilmenite concentrate with radioactive mineral content composed of zircon, monazite, and anatase. La concentration on zircon-ilmenite concentrate is 0–412 ppm, Ce is 0–80 ppm, Y is 27–82 ppm and zircon is 9,420–100,000 ppm. Avaibility of thorium at the bauxite laterite deposit on Singkep Island is closely related to the zircon, monazite, and anatase minerals. Characteristics of thorium availability in the bauxite laterite deposit are similar to the thorium characteristics of the primary and secondary tin deposits.