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At least 19 recordsLinked to original sources
PubMed1991

Natural radiation background in metropolitan Taipei.

A high-pressure ionization chamber was used to measure the natural background radiation in metropolitan Taipei, Taiwan, R.O.C. during a period in 1987-1988. The average exposure rate was 27.55 x 10(-10) C kg-1 h-1 including cosmic radiation, but the radon contribution was excluded. Scintillation survey meter, gamma-ray spectroscopy for soil samples, in-situ measurement with a NaI(Tl) detector coupled to a portable multichannel analyzer, instrumental neutron activation analysis of rock samples, and even thermoluminescent dosimeters were used as complementary measuring devices. Areas of higher radiation background were detected. They are the radium-bearing Peitou stones, an unusual occurrence of uraniferous zone at Sanhsia, and uranium precipitation in the glassy olivine basalt in a tea field at Tachi. All these areas are located in suburban sites of Taipei. Three types of building in Taipei City were selected for radon detection. No significantly elevated level of radon was detected, since Taipei is located in a semitropical area where ventilation of buildings is not a problem.

Background Radiation↗
PubMed2026

Radiation-resistant and desiccation-tolerant bacteria from the Chavara-Neendakara high background radiation area, india: phenotypic characterisation and genomic insights.

Radiation-resistant microorganisms that survive high doses of ionising radiation serve as valuable models for understanding stress adaptation; however, the genomic determinants underlying extreme radiation tolerance in bacteria from natural environments with high background radiation remain insufficiently characterised. Bacterial isolates from the Chavara-Neendakara HBRA (Kerala, India) were evaluated for desiccation tolerance, and the desiccation-resistant isolates were subsequently exposed to gamma irradiation (1-10 kGy) using a 60Co source. Isolates were identified through 16S rRNA sequencing, morphologically characterised by FE-SEM, and screened for antibiotic susceptibility. The highly radiation-resistant strain underwent whole-genome sequencing via Oxford Nanopore Technology, with De novo assembly, polishing, and genome annotation. Four bacterial isolates (Micrococcaceae and Paenibacillaceae) exhibited D10 values of 1-7 kGy, including one multidrug-resistant strain; no endospores were observed in the Paenibacillus isolate under the tested conditions. Paenibacillus sp. HBRA004 survived 10 kGy gamma radiation, exceeding all previously reported HBRA isolates by over fourfold. Its 5.0 Mbp genome (GC = 48.27%, ≥ 99% completeness) encodes five mechanistically independent DNA repair pathways; homologous recombination (recA, recN, radA), base excision repair (mutM, mutY, mutT), mismatch repair (mutL, mutS), nucleotide excision repair (uvrA, uvrB, uvrD), and non-homologous end joining (ku, ligD), alongside a redundant antioxidant network comprising triple-copy Fe/Mn-family superoxide dismutases and ahpC peroxiredoxin. A thioredoxin system (trxA, trxB, msrA) and manganese uptake via mntH may contribute to further layers of ROS defence. Their specific contribution to the HBRA004 phenotype remains to be experimentally and comparatively validated. These findings represent the first genomically characterised 10 kGy-resistant bacterial isolate from the Chavara-Neendakara HBRA, establishing a new benchmark for radiation tolerance within this ecologically significant environment. Pathway depth, gene copy amplification, and Mn/Fe homeostasis appear to be candidate mechanisms contributing to high-level radiation tolerance, consistent with patterns in other radiation-resistant taxa, though their contribution requires functional validation.

India↗
PubMed1991

Chromosome aberration, cancer mortality and hormetic phenomena among inhabitants in areas of high background radiation in China.

The respective average annual doses are about 330 and 110 mR/yr, in the high background radiation areas (HBRA) in Yangjiang County and the control areas (CA) in Enping and Taishan Counties. Both the HBRA and CA are in Guangdong Province which borders the South China Sea. The frequencies of chromosome aberration in circulating lymphocytes were examined for persons residing in the HBRA and CA. Those in the HBRA had increased frequencies of detectable abnormalities in stable aberrations (translocations and inversions) and unstable aberrations (dicentrics and rings). Previous reports have shown that when samples of circulating lymphocytes taken from inhabitants were tested in vitro for mitotic responses to phytohemagglutinin (PHA) and for the degree of unscheduled DNA synthesis (UDS) induced by UV-irradiation, there were higher responsiveness and UDS rates for those in the HBRA than in the CA. In contrast, mortality from all cancers and those from leukemia, breast and lung cancers that are inducible by radiation was not higher in the HBRA. Although the differences in the cancer mortality rates for the HBRA and CA are not significant, the findings are compatible with the assumption that the lower mortality from cancer in the HBRA is the result of the hormetic effects of the three-fold higher dose rate of background radiation in that areas. This assumption requires further study.

Adolescent↗
PubMed1975

Radioresistance in natural populations of Drosophila nebulosa from a Brazilian area of high background radiation.

D. nebulosa, collected in two woods of a high background radiation area (both in Iron Hills, State of Minas Gerais, Brazil), were compared to and found to be more resistant than flies collected as controls in two other woods of an adjacent area. This was the second time that average differences in radioresistance between natural populations were established. Previous experiments were carried out with D. willistoni, in the same area and in comparable fashion. In spite of their higher radiation resistance the flies from the radiation area carried a higher expressed load than the controls. The following tests were performed to estimate the differences: (a) survival, after whole body exposure to 90 000 R of 60Co-gamma-rays on 120 strains set up from single inseminated females and (b) reproductive performance, in 240 duplicate croses, measured in terms of the difference between irradiated series (males received 3000 R of 60Co-gamma-rays) and their unirradiated counterparts. The data are based on an offspring of 293784 individuals. Futhermore, two diallel crosses between sensitive and resistant strains have shown that the differences probably are due mainly to additive genes.

Animals↗
PubMed1990

Thyroid nodularity and chromosome aberrations among women in areas of high background radiation in China.

Thyroid nodularity following continuous low-dose radiation exposure in China was determined in 1,001 women aged 50-65 years who resided in areas of high background radiation (330 mR/yr) their entire lives, and in 1,005 comparison subjects exposed to normal levels of radiation (114 mR/yr). Cumulative doses to the thyroid were estimated to be of the order of 14 cGy and 5 cGy, respectively. Personal interviews and physical examinations were conducted, and measurements were made of serum thyroid hormone levels, urinary iodine concentrations, and chromosome aberrations in circulating lymphocytes. For all nodular disease, the prevalences in the high background and control areas were 9.5% and 9.3%, respectively. For single nodules, the prevalences were 7.4% in the high background area and 6.6% in the control area (prevalence ratio = 1.13; 95% confidence interval = 0.82-1.55). There were no differences found in serum levels of thyroid hormones. Women in the high background region, however, had significantly lower concentrations of urinary iodine and significantly higher frequencies of stable and unstable chromosome aberrations. Increased intake of allium vegetables such as garlic and onions was associated with a decreased risk of nodular disease, which seems consistent with experimental studies suggesting that allium compounds can inhibit tumor growth and proliferation. The prevalence of mild diffuse goiter was higher in the high background radiation region, perhaps related to a low dietary intake of iodine. These data suggest that continuous exposure to low-level radiation throughout life is unlikely to appreciably increase the risk of thyroid cancer. However, such exposure may cause chromosomal damage.

Autoantibodies↗
PubMed1992

[The reproductive potential of the bank vole (Clethrionomys glareolus Schreb) and of the tundra vole (Microtus oeconomus Pall.) under the conditions of the elevated radiation background of Bryansk Province].

The continuous irradiation (connected with the accident on the Chernobyl atomic power plant) by cesium-137 of the dominant species of rodents (Clethrionomys glareolus, Microtus oeconomus) in the forests of Bryansk Province had a deteriorating effect on the state of reproductive organs and on the course of embryogenesis, stimulated the reproduction cycle but inhibited the rate of sexual maturation and increased the death-rate of young animals. These effects resulted in significant ageing of the population. But all these phenomena provoked by radiation are within the limits of rodents adaptive capacities.

Accidents↗