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PubMed2002

Routine chest radiography following imaging-guided placement of tunneled central lines: a waste of time, money, and radiation.

BACKGROUND: This study sought to evaluate routine chest radiography following placement of tunneled central lines using combined ultrasound and fluoroscopic guidance. MATERIALS AND METHODS: A prospective study of 150 consecutive patients who underwent placement of tunneled central lines in the vascular radiology suite. Ultrasound-guided vein puncture was performed with an 18-gauge needle in each case, and the access site was noted. Line position was confirmed by fluoroscopy. Following the procedure, 50 patients had both an on-table digital chest radiograph and a conventional chest radiograph. Subsequent patients had a digital radiograph and a fluoroscopic image grab. Final line tip position was scored, and complications were recorded. RESULTS: Line placement was optimal (95%) or acceptable (5%) in all patients. Line tip position could be satisfactorily evaluated on supine fluoroscopy. Mean fluoroscopic x-ray dose was 0.5 cGy/cm2. Digital chest x-ray dose was 9.0 cGy/cm2, and formal chest radiography dose was 12.0 cGy/cm2. The only complications were 2 carotid artery punctures without clinical sequelae. CONCLUSION: When lines are placed under imaging guidance with ultrasound to direct the venous puncture, complications are rare and are not likely to be clinically important. Conventional and digital chest radiographs do not contribute clinically relevant information but do add to the radiation dose, time, and expense of the procedure.

Journal Article↗
PubMed2001

Ultraviolet protection by summer textiles. Ultraviolet transmission measurements verified by determination of the minimal erythema dose with solar-simulated radiation.

BACKGROUND: Apart from sunscreen lotions, clothing provides protection from acute and chronic sun damage. Therefore, it is very important to know the ultraviolet (UV) protection factor (UPF) of textiles, in particular of lightweight summer clothing. Usually, the UPF of a textile is determined by spectrophotometric assessment of the UV transmission (in vitro method). OBJECTIVES: To compare the relationship between in vitro tests and in vivo tests of UPF using solar simulators for determination of the minimal erythema dose (MED), applied to 30 different summer textiles. METHODS: Thirty summer textiles were spectrophotometrically assessed, and UPFs were calculated with respect to the International Commission on Illumination (CIE) erythemal action spectrum.1 Based on the in vitro UPFs 'on skin' and 'off skin', in vivo testing was performed using a solar simulator for the determination of the MEDunprotected and MEDprotected. RESULTS: The UPFs obtained from in vivo 'on skin' testing were significantly (r = 0.95; P < 0.001) lower than the predicted in vitro UPFs. This disparity was also confirmed by chromometric assessment of the MED testing; the erythemal responses measured after textile protection were significantly (P < 0.001) higher than those obtained without protection. However, the in vivo 'off skin' UPFs did not significantly (r = 0.98; P > 0.05) differ from the in vitro UPFs; comparison of the chromometrically assessed erythemal responses was also insignificant (P > 0.05). CONCLUSIONS: The different correlation between in vitro and in vivo measurements of the UPF may be due to the optical-geometrical properties of textiles and the different amount of direct and diffuse radiation passing through the spaces between the yarns. As spectrophotometric measurements of a textile may generally yield lower UPFs than those obtained under average field conditions, the in vitro test method provides 'safe' UPF values representing a 'worst-case scenario'. In contrast to in vitro testing, in vivo methods are much more expensive and time-consuming. Thus, with respect to practicality, spectrophotometric measurements seem to be most suitable for the evaluation of UV protection of textiles.

Adult↗
PubMed2005

Bystander cell proliferation is modulated by the number of adjacent cells that were exposed to ionizing radiation.

BACKGROUND: Direct cell-to-cell contact appears to be a prerequisite for the proliferative response of bystander WB-F344 cells co-cultured with irradiated cells; however, neither gap junctional intercellular communication nor long-range factors released into the medium appear to be involved (Cytometry 2003;56A:71-80). The present work investigated whether the proliferative bystander response depends on the number of irradiated cells (cells exposed to external gamma-rays or cells exposed to short-range beta-particles emitted by DNA-incorporated (3)H-thymidine) that are adjacent to unirradiated bystander cells. METHODS: Subconfluent monolayers of rat liver epithelial cells (WB-F344) were incubated in the presence of (methyl-(3)H)thymidine at a concentration of 5.8 kBq/ml for 18 h. Radiolabeled cells containing 0.7 x 10(-3) Bq/cell (absorbed dose: 0.14 Gy) were plated together with unlabeled cells in proportions of 6% and 94%, 12% and 88%, 25% and 75%, 50% and 50%, and 75% and 25%, respectively, keeping constant the total number of plated cells. In a parallel experiment, cells acutely exposed to 5 Gy of (137)Cs gamma-rays were plated with unirradiated cells in the same proportions. In both experiments, cells were co-cultured for 24 h followed by a flow cytometric study of their proliferation. The two cell populations in the co-cultures were distinguished by staining one population with carboxyfluorescein diacetate, succinimidyl ester, which metabolizes intracellularly. RESULTS: Increasing the fraction of irradiated cells relative to unirradiated bystander cells led to an increase in proliferation of bystander cells. Specifically, in co-cultures in which irradiated cells were initially mixed with unirradiated cells in proportions of 50% and 50% and of 75% and 25%, respectively, bystander cells showed a statistically significant increase of their proliferation compared with the controls. CONCLUSIONS: The proliferative response of WB-F344 bystander cells is modulated by the number of adjacent cells that are exposed to ionizing radiation from external gamma-rays or intracellularly emitted (3)H beta-particles.

Animals↗
PubMed2000

New technique for producing hybridoma by using laser radiation.

BACKGROUND AND OBJECTIVE: With conventional methods, cell fusion rate is extremely low, and fusion of two specific cells is not possible. We developed a new method for inducing cell fusion under the microscope by using a microprocessing device by laser. STUDY DESIGN/MATERIALS AND METHODS: Under a microscope, the target cells were irradiated with laser beams for trapping. Then, the trapped cells were transferred and placed in contact with the corresponding cells, which were also fixed by laser beam. The pulse laser beams are focused on the contact surface to cut small perforations for mutual communication of the cytoplasms. RESULTS: The fusion rate of mouse myeloma cells was 38%. The rate of hybridoma production of myeloma cell and lymphocyte was 2%. We confirmed the proliferation of the newly formed hybridoma in HAT medium and the production of immunoglobulin G. CONCLUSION: This new cell fusion method is characterized by production of hybridomas of target cells, lower cell toxicity, and a high rate of hybrid production.

Animals↗
PubMed2004

Differences in production of melanin radicals by 694 nm ruby laser and UVA radiation.

BACKGROUND AND OBJECTIVES: The 694 nm ruby laser is used clinically for hair removal and the mechanism is predominantly photo thermal via melanin targeting. We investigated 694 nm laser-irradiation of human hair, and laser-irradiation of synthetic dopa melanin to establish whether photolysis and oxygen radical production is also contributory, and which may have side effects. STUDY DESIGN/MATERIALS AND METHODS: Ultraviolet-A (UVA) irradiation of melanin was used as a positive control for radical production. Laser- and UVA-irradiated hair samples, and synthetic dopa melanin in media of different viscosity, were analyzed using electron spin resonance spectroscopy, and compared. The spin trap 5,5-dimethyl- 1-pyrroline N-oxide (DMPO) was used to probe laser-irradiated dopa melanin for superoxide radical production. RESULTS: Comparable to UVA, laser-irradiation of hair increased the signal-intensity of the intrinsic melanin radical. UVA-induced radicals decay rapidly; however, laser-induced radicals decayed slowly and did not fully revert to original levels after 24 hours. Laser-induced radicals were increasingly stable with viscosity of the medium. Superoxide radicals were detected using DMPO in UVA- but not laser-irradiated synthetic dopa-melanin at pH 4.5. CONCLUSIONS: Laser-irradiation of melanin does not result in oxygen radical formation; however, a paramagnetic species, long-lived in rigid media, is detected which is worth further investigation.

Free Radicals↗
PubMed2004

Young adult survivors of childhood acute lymphoblastic leukemia: spontaneous GH secretion in relation to CNS radiation.

BACKGROUND: Young adults who are long-term survivors of acute lymphoblastic leukaemia (ALL) in early childhood usually do well and do not have to go to regular medical checkups. Many of these survivors did receive prophylactic cranial radiotherapy during their oncological treatment. The effect of cranial irradiation on the hypothalamus is considered to be progressive. Therefore, late effects, such as reduced growth hormone (GH) secretion, may remain undetected until adulthood. PROCEDURE: Records from all patients treated for ALL before the onset of puberty in the region of West Sweden, between 1 January 1973 and 31 December 1985 were included, provided they were in first remission with a minimum follow-up time of 15 years, and a minimum age of 20. These criteria were met by 47 young adults aged 20-32 years, of whom 35 agreed to participate. We studied spontaneous GH secretion over 24 hr, IGF-I and IGFBP-3, final height and BMI. The patients had been treated according to three consecutive Swedish childhood leukaemia group protocols. The median follow-up time was 20 years, and 19 of the patients had been treated with cranial irradiation (CRT+), 16 had not (CRT-). RESULTS: CRT+ patients had significantly lower maximal peaks of GH than CRT- patients. Fifty percent of the CRT+ patients had a GH(max) below the cut-off level (3.3 microg/l), for GH treatment. CRT- patients all had GH(max) levels considered within the normal range. Final height of all the patients, except one CRT+ women, was in the range of expected midparental height, the median loss in final height in the CRT+ patients was 0.8 standard deviation (SD). No patient in this study was obese by definition (BMI <30 kg/m(2)). IGF-I and IGFBP-3 concentrations did not correlate to variations in spontaneous GH secretion in these patients. CONCLUSIONS: In spite of the little effect on final height, we found impaired spontaneous GH secretion in 79% of young adults 20-32 years of age, and GH deficiency (GHD) in 47% after low-dose cranial irradiation in early childhood. The consequences of this low-GH secretion need to be investigated.

Adult↗
PubMed2006

Dose escalation study of docetaxel and nedaplatin in patients with relapsed or refractory squamous cell carcinoma of the esophagus pretreated using cisplatin, 5-fluorouracil, and radiation.

BACKGROUND: Definitive chemoradiation with cisplatin (CDDP) and 5-fluorouracil (5FU) has been playing an important role in the treatment of esophageal cancer, but some patients are not curable or have recurrent lesions. However, few chemotherapeutic regimens are available for such patients. Docetaxel and nedaplatin are active for esophageal cancer. We conducted a dose-escalation study of docetaxel and nedaplatin as second line-chemotherapy after definitive chemoradiation in patients with relapsed or refractory squamous cell carcinoma of the esophagus after chemoradiation. METHODS: Nedaplatin was administered on day 1 and docetaxel was administered on days 1 and 15, every 4 weeks. Dose escalation was based on the dose-limiting toxicity (DLT) observed during the first cycle. RESULTS: Twelve patients were enrolled. At a docetaxel dose of 30 mg/m(2) and a nedaplatin dose of 80 mg/m(2), one grade 4 neutropenia occurred and caused one treatment break longer than 2 weeks, but there were few DLTs. At doses of 35 and 80 mg/m(2), respectively, two grade 4 neutropenias and one grade 2 thrombopenia occurred and caused three treatment breaks longer than 2 weeks. Therefore, the maximum tolerated dose was established at this dose level. Two grade 3 anorexias and one grade 3 nausea occurred, but other non-hematological toxicities were generally mild. Responses were seen in one-fourth of the 12 patients, including one complete remission. CONCLUSION: The recommended doses of docetaxel and nedaplatin were 30 and 80 mg/m(2), respectively. This combination could be a potential second-line treatment for this target population.

Aged↗
PubMed2003

Molecular requirements for the combined effects of TRAIL and ionising radiation.

BACKGROUND AND PURPOSE: Previously it was shown that combination of death ligand TRAIL and irradiation strongly increases cell kill in several human tumour cell lines. Since Bcl-2 overexpression did not strongly interfere with the efficacy, components of the mitochondrial death pathway are not required for an effective combined treatment. In the present study the minimal molecular prerequisites for the efficacy of a combined treatment were determined. MATERIALS AND METHODS: Apoptosis induction in control, caspase-8 and FADD negative Jurkat cells, BJAB control and FADD-DN cells was analysed by FACS. Activation of caspase-8, -10 and -3 and cleavage of PARP was determined by immunoblotting. TRAIL receptors were activated using recombinant human TRAIL. Surface expression of TRAIL receptors DR4 and DR5 was analysed by FACS. RESULTS: Jurkat T-cells express the agonistic DR5 receptor but not DR4. Presence of FADD was found to be essential for TRAIL induced apoptosis. Caspase-8 negative cells show very low rates of apoptosis after prolonged stimulation with TRAIL. No combined effects of TRAIL with irradiation could be found in FADD-DN overexpressing and FADD deficient cells. However, the combination of TRAIL and irradiation clearly lead to a combined effect in caspase-8 negative Jurkat cells, albeit with reduced death rates. In these cells activation of the alternative initiator caspase-10 could be detected after combined treatment. CONCLUSION: Our data show that a combined therapy with TRAIL and irradiation will only be effective in cells expressing at least one agonistic TRAIL receptor, FADD and caspase-8 or caspase-10.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Combined modality therapy of A431 human epidermoid cancer using anti-EGFr antibody C225 and radiation.

BACKGROUND: Monoclonal antibodies (mAb) to epidermal growth factor receptor (EGFr) inhibit tumor cell proliferation and enhance cytotoxicity of chemotherapeutic agents. The purpose of this study was to investigate the interaction of the anti-EGFr antibody C225 combined with radiotherapy (RT) on EGFr expressing A431 human epidermoid cancer cells. METHODS: Cell proliferation, apoptosis, EGFr expression and phosphorylation, and clonogenic survival were assayed in vitro. A431 tumor growth inhibition and immunohistochemistry analysis of EGFr expression and apoptosis were assessed in vivo. RESULTS: C225 plus RT produced greater inhibition of A431 cell proliferation than C225 or RT alone which was corroborated by enhanced apoptosis. Similar clonogenic survival occurred following the addition of C225 to RT, although colonies were smaller in the presence of C225. C225 produced inhibition of EGF-induced phosphorylation of EGFr without concurrent down-regulation of surface receptor, which was not altered by RT. Combined treatment of mice bearing tumors demonstrated enhancement of complete regressions, reduction in time to tumor size doubling, and prolongation of survival. Significant apoptosis occurred in xenograft tumors treated with C225 with or without RT. CONCLUSIONS: These data demonstrate an interaction between C225 and RT. C225-mediated apoptosis and inhibition of EGFr phosphorylation may be critical in the interaction. Studies to define the precise influence of combined modality treatment on the EGFr signal transduction cascade need to be pursued. The combination of growth factor receptor antibodies and RT has potential application in clinical oncology.

Animals↗
PubMed1996

Treatment of ovarian cancer with surgery, short-course chemotherapy and whole abdominal radiation.

BACKGROUND: The primary aim was to induce a high number of pCR in early (FIGO IC, IIB + C) - and advanced (FIGO III-IV) - stage ovarian cancer with a surgery plus 4 cycles of cisplatin and melphalan (PAMP) regimen. The second objective was to prevent relapse with WAR in patients in remission after chemotherapy. PATIENTS AND METHODS: 218 eligible patients were treated after staging laparotomy with cisplatin 80 mg/sqm i.v. on day 1 and melphalan 12 mg/sqm i.v. on day 2 q 4 weeks. Response was verified by second-look laparotomy. WAR was carried out with the open field technique on a linear accelerator (daily dose: 1.3 Gy, total dose: 29.9 Gy) in patients with pathological or clinical CR or pathological PR with microscopical residual disease. RESULTS: 146/218 patients (67%, 95% CI: 61%-73%) responded to PAMP: 56 (26%) achieved pCR, 24 (11%), cCR, 56 (26%) pPR and 10 (5%) cPR (c = clinical, p = pathological). Multivariate analyses revealed that in advanced stages (92 cases in remission), the achievement of pCR was the most important factor for longer time to failure (TTF) and survival. Only 51/118 (43%) patients in remission received WAR. Early-stage patients <= 55 years were more likely to have WAR than patients older than 55 years (77% vs. 23%; p = 0.02). Advanced-stage patients with cCR were less likely to be irradiated than patients with pCR or pPR (10% vs. 51%; p = 0.003). Toxicity of PAMP was acceptable with 10% of WHO grade 4 hematologic toxicity. Acute hematological toxicity of WAR caused interruption (33%) or incompleteness (33%) of irradiation in the majority of patients. CONCLUSIONS: PAMP is an effective treatment for advanced ovarian cancer with a 67% response rate after 4 cycles. For the majority of patients in remission, WAR as a consolidation treatment was hardly feasible. For these patients new treatment modalities to consolidate remission are needed.

Adult↗
PubMed1995

[The postoperative therapy of epithelial ovarian carcinoma. Has systemic cytostasis replaced percutaneous radiation?].

BACKGROUND: Abdominopelvic external beam radiotherapy as a primary postoperative therapy after a comprehensive surgical staging in completely resected stages ovarian carcinoma has been used worldwide less frequently during the last decade despite proven curative effects of this therapeutic modality. Systemic chemotherapy, mostly platinum-based combination chemotherapy, has been established as a postoperative routine treatment because of the high response rates achieved in advanced cases of disease. The controversy concerning the choice of chemotherapy continues and gave rise to a review of recently reported treatment outcome data. PATIENTS AND METHODS: As a result of the low incidence of ovarian carcinoma diagnosed in early stages, only a few randomized clinical trials have been performed of both systemic chemotherapy and external beam radiotherapy in intermediate/high risk patients. Thus we collected data based on a review of the literature with special regard to criteria recommended to select patients for postoperative abdominopelvic radiotherapy and chemotherapy respectively. RESULTS: Despite high response rates and high negative second-look operation findings to chemotherapy, the rates for cures and long-term survival have not been improved significantly and have also failed to show a significant advantage compared with results achieved by the use of external beam radiotherapeutic modalities. CONCLUSIONS: Long-term survival rates of the relative small number of ovarian carcinoma patients in the early stages treated in prospective randomized trials comparing both treatment modalities do not justify the assumed superiority of chemotherapy over radiotherapy, but demonstrate the need and underline the importance of further randomized clinical trials. Abdominopelvic irradiation following staging laparotomy is not recommended for advanced stages and has at the most limited benefit as consolidation therapy after successfully cytoreductive chemotherapy depending on the amount of residual tumor.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

[The phospholipid composition of the liver in root voles living under different radioecological conditions].

The effect of the increased natural radiation background (within some areas in Komi Republic) and man-caused radioactive contamination in the Chernobyl NPP accident zone on the composition of liver phospholipids in Microtus oeconomus inhabiting these areas was studied. The significant changes in the liver lipid composition in rodents inhabiting both the Chernobyl accident zone and the areas with the increased natural radiation background were found. The maximal changes in the liver phospholipid composition were revealed during the first year after the accident. The reverse dependence between the phosphatidyl choline/phosphatidyl ethanolamine ratio and the ratio between the sum of more readily oxidizable phospholipids and the sum of more poorly oxidizable ones was found. However, the slope of corresponding curves significantly depends on the radioactive state in the area of the population inhabitance. The conclusion about high sensitivity of the lipid composition of hepatocytes in Microtus oeconomus both to the impact of the man-caused radioactive contamination and the increased level of the natural radioactivity was drawn.

Air Pollution, Radioactive↗
PubMed2003

Determination of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb concentration in excreta samples of inhabitants of a high natural background area.

The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper, the concentrations of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1) for 238U, 9.2 +/- 4.0 mBq g(ash)(-1) for 234U, 7.0 +/- 4.2 mBq g(ash)(-1) for 232Th, 256.1 +/- 134.6 mBq g(ash)(-1) for 228Th, 335.5 +/- 192.8 mBq g(ash)(-1) for 228Ra, 156.6 +/- 74.1 mBq g(ash)(-1) for 226Ra and 66.7 +/- 17.7 mBq g(ash)(-1) for 210Pb. The results were compared with background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.

Background Radiation↗
PubMed1996

Pilot study of the Urals population by tooth electron paramagnetic resonance dosimetry.

During 1949-1956, about 76 x 10(6)m3 of radioactive liquid waste containing a total activity of 10(17) Bq was discharged into the Techa River by the first Russian industrial nuclear facility Mayak. As a consequence, the population living in the river valley received considerable internal and external radiation doses. The results of a first application of electron paramagnetic resonance (EPR) of tooth enamel for a retrospective individual dose evaluation of the residents of the Techa riverside are presented. Three main contributions to the dose absorbed in tooth enamel have been considered: external exposure mainly from the Techa River sediments, internal exposure mainly due to 90Sr; and background radiation including all other sources of exposure except the Techa River. The teeth of 86 inhabitants of the town Kamensk-Uralskii were analysed to determine the age-dependent contribution of the background radiation to the enamel dose. For 22 residents of the middle and lower Techa riverside, measurements of the 90Sr whole-body content and EPR measurements of the absorbed dose in enamel were used to establish a correlation between these two quantities. Finally, absorbed doses in the enamel of five residents of the upper Techa riverside were determined by EPR method. Contributions of the background radiation and the internal 90Sr contamination were subtracted to determine the external exposure of the residents.

Aged↗
PubMedDate not supplied

[Genetic monitoring of natural Drosophila populations in radiation contaminated regions of Belarus].

Genetic monitoring of natural Drosophila melanogaster populations inhabiting regions of Belarus with different radiation background (Vetka and Svetilovichi villages), radonuclide-contaminated after the Chernobyl accident, compared with populations from the Berezinsky biosphere reserve (the control area) were conducted. The dominant and recessive lethal mutation levels and genetic structure of the populations were analyzed for frequencies of F- and S-alleles of Adh (alcohol dehydrogenase) of Gpdh (glycerinophosphate dehydrogenase) and Sod (superoxide dismutase) loci. Populations inhabiting the regions with high radiation background exhibited higher frequency of lethal mutations and higher heterozygosity than those from the control area. Moreover, higher frequency of polymorphous Sod locus S-allele was detected in these populations. Apparently, Sod S-alleles are more adaptively valuable under conditions of high radiation background, because as is known, superoxide dismutase is an effective radioprotector at all levels molecular, cellular and organism. Adaptation of populations to stress impacts was analyzed, since 1998. Nonspecific adaptation of natural Drosophila melanogaster populations from Vetka and Svetilovichi villages of Gomel region was reveled. They are higher adapted than the control population from the Berezinsky biosphere reserve to both ionizing radiation effect and to chemical mutagen EMS. After laboratory cultivation within 6-8 generations without irradiation adaptation to radiation in the population from radiocontaminated regions remained. The content of samples from the control natural drosophila population in the laboratory conditions is an environmental stress that led to the formation of nonspecific adaptation within 6-8 generations to unfavorable factors, including ionizing radiation. It should be taken into account that the population adaptation is formed via death of sensitive genotypes at various ontogenesis stages.

Adaptation, Physiological↗
PubMed1982

Effects of low-dose radiation - a correlation study.

The effects of low-dose radiation have been a matter of controversy over the years, and the epidemiologic results have been conflicting. A couple of recent studies have indicated a possible impact on lung cancer mortality from exposure to indoor levels of radon and radon daughters. In this study, selected mortality rates, ie, lung cancer, pancreatic cancer, breast cancer (females only), leukemia, and multiple myeloma were correlated for the counties of Sweden with estimates of average background radiation exposure in these areas. Significant correlations were obtained for lung cancer (males, r = 0.46; females r = 0.55) and pancreatic cancer (males, r = 0.59; females, r = 0.40) , and there was a borderline correlation (r = 0.36; p = 0.04) for leukemia in males. In all, there were positive correlations for eight out of the nine computations made. Since background radiation correlates with urbanization and therefore with smoking, air pollution, etc, the correlations might be spurious due to confounding; on the other hand confounding is a reciprocal phenomenon which suggests that background radiation should to be taken into consideration when widespread risk factors like smoking, coffee drinking, general air pollution, etc, are studied.

Adult↗
PubMed2002

Terrestrial isopods congregate under a low-level beta-emitter source.

Ionizing radiation is ubiquitous, but very few experiments have investigated the biological effects of the natural background radiation at very low doses (>10 mGy/yr). We examined whether the background radiation, or radiation of a slightly higher level, has a role in evoking changes in behaviors of terrestrial isopods (woodlice). Upon exposure to a source giving 15 times the background level placed at one end of a box, a significant increase in the number of woodlice gathering under the beta-source was observed with time, as compared with the sham control. Terrestrial isopods have chemoreceptors (the olfactory system) on the terminal segment of their antennae. An additional experiment confirmed the involvement of these antennae in the radiation effect on behavior. After the excision of the antennae, no beta-taxis response was observed. The behavior of the group exposed to the source giving 30 times the background tended to decrease gradually in the area of the source, and the individuals aggregated in the area away from the source. Thus, the olfactory sensor in the antennae may be an important organ involved in the prompt response to radiation exposure, and the discrimination of the radiation field strengths of radioisotopes.

Animals↗