Revisiting HERQL, the hernia-specific quality-of-life assessment instrument, to extend the clinical applicability for abdominal wall hernias.

PURPOSE: In the past we have developed and validated the hernia-specific quality of life assessment instrument, HERQL, for groin hernias. In current study we evaluated the conceptual structure and validated HERQL for abdominal wall hernias. METHODS: Subjective quality-of-life perceptions from abdominal wall hernia patients were assessed. Clinical responsiveness was evaluated comparing treatment naïve with follow-up hernia patients. Measurement invariance between groin and abdominal wall hernias was approached with structural equation modeling (SEM). Subgroup comparisons were conducted between primary ventral and incisional hernias, as well as the presence of co-morbidity, hernia incarceration, surgical complications, and recurrent abdominal wall hernias. RESULTS: A total of 775 HERQL assessments, including 167 from abdominal wall hernias, were successfully performed. Cronbach's alpha coefficients for the summative pain, worse symptoms for treatment-naïve patients, and improving summative pain scores across the pre-operative, immediately post-operative, and post-operative 3-month assessments indicating clinical responsiveness were observed and comparable between groin and abdominal wall hernias. Configural invariance was evidenced by that the same model held true for both types of hernias with multi-group SEM, while mean structure exploration showed that abdominal wall hernia patients reported less latent summative pain (- 0.535, p < 0.0001) but worse latent quality-of-life score (0.207, p < 0.0001). Patients with peri-operative complications suffered from worse pain during mild activities (2.7 versus 1.5, p = 0.01), and patients with recurrent hernias reported compromised global health/quality of life (2 versus 1.6, p = 0.001). CONCLUSIONS: The study successfully validated and extended the clinical applicability of HERQL across distinct types of hernias. Measurement invariance was ascertained and the same HERQL construct could be administered for both abdominal wall and groin hernias in Taiwan.

Magnetic Resonance Spectroscopy in Living-Donor Liver Transplantation.

OBJECTIVE: The purpose of this study is to evaluate the accuracy rate of the one breath-hold single voxel hydrogen-1 magnetic resonance spectroscopy (MRS) in comparison with intraoperative biopsy for liver fat quantification in living-donor liver transplantation. MATERIALS AND METHODS: A total of 80 living liver donors participated in this study. Each patient underwent both MRS and intraoperative biopsy for evaluation of liver fatty content. MRS was performed using 1.5-T magnetic resonance imaging and placed in segments 2-4, 5-8, and left lateral segment for each donor. Accuracy was assessed through receiver operating characteristic curve analysis. Sensitivity and specificity of MRS fat fractions were also calculated. RESULTS: Eighty living-donor liver transplantation donors were enrolled in this study. There was no fatty liver in 59 subjects (73.8%), 5% to 10% fatty liver in 17 subjects, 11% to 15% fatty liver in 3 subjects, and >16% fatty liver in 1 subject. MRS fat fraction showed excellent parameters to predict between normal liver and fatty liver groups (1.85% ± 0.98, 8.13% ± 3.52, respectively; P < .0001). Linear regression between MRS fat fraction and pathology grading showed high correlation (R(2) = 0.7092). Pearson correlation revealed high correlation between MRS and pathology results (r = 0.936), poor correlation between body mass index and pathology results (r = 0.390). The sensitivity and specificity for detection of liver steatosis in MRS fat fraction were 95.2% and 98.3%, respectively. CONCLUSION: (1)H MRS fat fraction is a highly precise and accurate method in quantification of hepatic steatosis for the living donor and can be finished in a single breath-hold.

Association of Attention deficit hyperactivity disorder and Kawasaki disease: a nationwide population-based cohort study.

AIMS: The association between Kawasaki disease (KD) and Attention deficit hyperactivity disorder (ADHD) has rarely been studied. In this study, we investigated the hypothesis that KD may increase the risk of ADHD using a nationwide Taiwanese population-based claims database. METHODS: Our study cohort consisted of patients who were diagnosed with KD between January 1997 and December 2005 (N = 651). For a comparison cohort, five age- and gender-matched control patients for every patient in the study cohort were selected using random sampling (N = 3255). The cumulative incidence of ADHD was 3.89/1000 (from 0.05 to 0.85) in this study. All subjects were tracked for 5 years from the date of cohort entry to identify whether or not they had developed ADHD. Cox proportional hazard regression analysis was performed to evaluate 5-year ADHD-free survival rates. RESULTS: Of all patients, 83 (2.1%) developed ADHD during the 5-year follow-up period, of whom 21 (3.2%) had KD and 62 (1.9%) were in the comparison cohort. The patients with KD seemed to be at an increased risk of developing ADHD (crude hazard ratio (HR): 1.71; 95% confidence interval (CI) = 1.04-2.80; p < 0.05). However, after adjusting for gender, age, asthma, allergic rhinitis, atopic dermatitis and meningitis, the adjusted hazard ratios (AHR) of the ADHD in patients with KD showed no association with the controls (AHR: 1.59; 95% CI = 0.96-2.62; p = 0.07). We also investigated whether or not KD was a gender-dependent risk factor for ADHD, and found that male patients with KD did not have an increased risk of ADHD (AHR: 1.62; 95% CI = 0.96-2.74; p = 0.07) compared with the female patients. CONCLUSIONS: The findings of this population-based study suggest that patients with KD may not have an increased risk of ADHD and whether or not there is an association between KD and ADHD remains uncertain.

Prolonged time to pregnancy in residents exposed to ionising radiation in cobalt-60-contaminated buildings.

OBJECTIVES: Radiation-induced cytogenetic damage in somatic cells has raised concern that low-dose ionising radiation can also damage germ cells and influence gamete production and/or function, resulting in decreased fertility. Time to pregnancy (TTP) was used to investigate whether exposure to gamma-radiation affected fertility among the residents of cobalt-60-contaminated buildings in Taiwan. METHODS: This was a retrospective pregnancy-based study of 357 pregnancies born to 124 exposed couples. Both the cumulative dose and the dose rate for each pregnancy was estimated based on a physical dose reconstruction programme. The comparison population consisted of 612 pregnancies born to 225 couples randomly sampled from the Taiwan general population. Information on TTP was collected by personal interviews. Fecundability ratios (FRs) were calculated with a discrete proportional hazards model. RESULTS: For exposed mothers, fertility decreased significantly when unprotected intercourse began during the period of living in the radiation-contaminated buildings (FR 0.75, 95% CI 0.61 to 0.92). The effect was borderline significant for fathers (FR 0.83, 95% CI 0.68 to 1.02). There was evidence that prolonged TTP was associated with the rate of exposure for both mothers and fathers (tests for trend: female, p=0.0006; male, p=0.03), especially evident for dose rates > or =10 mSv/year (female, FR 0.60, 95% CI 0.43 to 0.84; male, FR 0.68, 95% CI 0.49 to 0.96). CONCLUSIONS: Our findings suggest that exposure to low-dose ionising radiation of cobalt-60-contaminated buildings may decrease fertility, especially in females. Fertility declined with increasing concurrent dose but not with cumulative dose.

Cancer risks in a population with prolonged low dose-rate gamma-radiation exposure in radiocontaminated buildings, 1983-2002.

PURPOSE: To assess cancer risks in a population that received prolonged low dose-rate gamma-irradiation for about 10 years as a result of occupying buildings containing 60Co-contaminated steel in Taiwan. MATERIALS AND METHODS: The cancer risks were compared with those populations with the same temporal and geographic characteristics in Taiwan by standardized incidence ratios (SIR), adjusted for age and gender. The association of cancer risks with excess cumulative exposure was further evaluated for their relative risks by the Poisson multiple regression analysis. RESULT: A total of 7271 people were registered as the exposed population, with 101,560 person-years at risk. The average excess cumulative exposure was approximately 47.8 mSv (range < 1 - 2,363 mSv). A total of 141 exposed subjects with various cancers were observed, while 95 developed leukemia or solid cancers after more than 2 or 10 years initial residence in contaminated buildings respectively. The SIR were significantly higher for all leukemia except chronic lymphocytic leukemia (n = 6, SIR = 3.6, 95% confidence interval [CI] 1.2 - 7.4) in men, and marginally significant for thyroid cancers (n = 6, SIR = 2.6, 95% CI 1.0 - 5.7) in women. On the other hand, all cancers combined, all solid cancers combined were shown to exhibit significant exposure-dependent increased risks in individuals with the initial exposure before the age of 30, but not beyond this age. CONCLUSIONS: The results suggest that prolonged low dose-rate radiation exposure appeared to increase risks of developing certain cancers in specific subgroups of this population in Taiwan.

Long driving time is associated with haematological markers of increased cardiovascular risk in taxi drivers.

AIMS: To examine the association between driving time and changes in haematological markers of increased risks for cardiovascular diseases (CVD). METHODS: The authors conducted a cross sectional analysis of baseline data from the Taxi Drivers' Health Study cohort in Taipei, Taiwan. They retrieved information on comorbidity, laboratory tests, age, and anthropometric measures from medical records of 1157 subjects (mean age 44.6 (SD 8.6) years). Whole blood cell (WBC) count was used as the primary haematological marker for increased CVD risk, and platelet count and haematocrit as the secondary markers. Standardised questionnaires were implemented to collect information on demographics, lifestyle, work related physical and psychosocial factors, and driving time profiles. Multiple regression was used to estimate the adjusted effects of driving time on three haematological markers. RESULTS: The mean measured hematological marker was 6656 (SD 1656) cells x10(6)/l for WBC, 47.2 (SD 3.5) % for hematocrit, and 243 (SD 52) cells x10(9)/l for platelets. The driving time was 264 (SD 76) hours/month. Compared with drivers who drove < or =208 hours/month (1st quartile cut off), drivers who drove >208 hours/month had a higher WBC count (by 317 x10(6)/l; 95% CI 99 to 535), haematocrit (by 0.8%; 95% CI 0.3 to 1.2), and platelets (7.9 x10(9)/l; 95% CI 1.0 to 14.8). After adjusting for conventional CVD risk factors (age, sex, smoking, hypertension, diabetes, and hypercholesterolaemia), obesity, alcohol drinking, regular exercise, and sociodemographics (education, marital status, income, and so on), long driving time was still associated with significant increases in WBC and platelets, whereas the effect on haematocrit was diminished and became statistically non-significant. Additional controls for physical workload, self-perceived job stress, and job dissatisfaction did not alter the associations with increased WBC and platelets. CONCLUSIONS: Longitudinal studies are needed to confirm the observed cross sectional association and to further examine the specific occupational exposures accountable for the association between driving time and haematological markers of systemic inflammation and haemostatic alteration.

Occupational and personal factors associated with acquired lumbar spondylolisthesis of urban taxi drivers.

AIMS: To investigate the occupational and personal factors associated with lumbar spondylolisthesis in taxi drivers. METHODS: Cross-sectional analysis of the baseline data from the Taxi Drivers' Health Study cohort. Information was retrieved from the medical records of standardised lumbosacral spine plain films, age, and anthropometric measures of 1242 subjects. Acquired spondylolisthesis (ASL) was defined as non-lytic spondylolisthesis involving lumbar spines above L5. Questionnaires were used to gather information on demographic features, health behaviours, exercise, work related physical and psychosocial factors, and driving time profiles. Multiple logistic regression was used to model the odds ratio (OR) for prevalent ASL cases associated with personal and occupational factors. RESULTS: A total of 40 cases (3.2%) of ASL were diagnosed. Among those driving < or =5 years, 6-15 years, and >15 years, the estimated prevalence of lumbar spondylolisthesis was 1.1%, 2.4%, and 7.1% respectively. Results of multiple logistic regression suggested that taxicab driving >15 years (OR = 3.4, 95% CI 1.1 to 10.7, compared to driving < or =5 years), age (OR = 2.6, 95% CI 1.1 to 6.6 for age 46-55; and OR = 4.8, 95% CI 1.8 to 12.9 for age >55), body mass index > or =25 kg/m2 (OR = 2.2, 95% CI 1.1 to 4.6), and frequent strenuous exercise (OR = 2.2, 95% CI 1.1 to 4.5) were significantly associated with higher prevalence of spondylolisthesis. There was a consistent likely exposure-response relation between professional seniority and ASL prevalence. CONCLUSIONS: Longitudinal studies are needed to confirm the observed association between professional driving and spondylolisthesis, and to examine further the specific occupational exposures accountable for this association.

Predictors of whole-body vibration levels among urban taxi drivers.

To identify a set of important WBV predictors that could be used to develop a statistical instrument for exposure assessment in a large epidemiologic study, a total of 432 WBV measures were taken from a sample of 247 male drivers in Taipei City, Taiwan. In accordance with the ISO 2631-1 (1997) methods, we measured the frequency-weighted vertical acceleration (z-axis) over drivers' seat surface, under conditions representing different types of rides (vacant vs. short vs. long) assigned to random destinations. Mixed effect models were used to analyse the WBV data including repeated measures. For this group of urban taxi drivers regularly exposed to WBV of low intensity (mean = 0.31 ms( - 2), ranging from 0.17 to 0.55 ms( - 2) r.m.s.), our analyses indicated that average driving speed was the primary predictor (p < 0.0001). As average driving speed increased, measured vertical acceleration increased in a quadratic-linear manner (p < 0.0001). Other WBV predictors, after adjusting for the effects of other covariates, included automobile manufacturer (p = 0.02), engine size (p = 0.04), body weight (p = 0.002), age (p = 0.02), use of seat cushion (p = 0.03), and traffic period (p = 0.02). Our study suggests that a similar statistical approach could be employed in future studies to improve the quality and efficiency of WBV exposure assessment in professional drivers.

HUMN project: detailed description of the scoring criteria for the cytokinesis-block micronucleus assay using isolated human lymphocyte cultures.

Criteria for scoring micronuclei and nucleoplasmic bridges in binucleated cells in the cytokinesis-block micronucleus assay for isolated human lymphocyte cultures are described in detail. Morphological characteristics of mononucleated cells, binucleated cells, and multinucleated cells as well as necrotic and apoptotic cells and nuclear buds are also described. These criteria are illustrated by a series of schematic diagrams as well as a comprehensive set of colour photographs that are of practical assistance during the scoring of slides. These scoring criteria, diagrams and photographs have been used in a HUman MicronNucleus (HUMN) project inter-laboratory slide-scoring exercise to evaluate the extent of variability that can be attributable to individual scorers and individual laboratories when measuring the frequency of micronuclei and nucleoplasmic bridges in binucleated cells as well as the nuclear division index. The results of the latter study are described in an accompanying paper. It is expected that these scoring criteria will assist in the development of a procedure for calibrating scorers and laboratories so that results from different laboratories for the cytokinesis-block micronucleus assay may be more comparable in the future.

Spread of 60Co contaminated steel and its legal consequences in Taiwan.

Since 1992, over 200 civilian residential and school buildings in Taiwan have been identified to have contained 60Co contaminated steel rebar emitting excessive gamma-radioactivity in living environments. These buildings were mostly constructed in early 1983 and 1984 by employing steels from one steel mill, which had recycled unknown 60Co orphan sources in northern Taiwan. In 1994, a group of residents who once stayed for a protracted period up to 10 y in the contaminated Ming-Sheng Villa filed a civil action against Taiwan's nuclear regulatory office, the Atomic Energy Council, for state tort compensation of 3.4 M U.S. dollars in equivalent. After three years of court processes, the Taipei District Court handed down a decision in partial favor of the exposed residents. Both parties soon appealed against this judgment to the Taiwan Appellate Court. This article analyzes the main legal issues involved, including government's obligations to prevent and eliminate contamination, to take preventive measures, and to take necessary remedial measures; and plaintiffs' assertion on any legal right against governmental offices. Moreover, discussion issues contain the scope of damage and compensation, causation analysis, absence of effective and efficient regulation over radioactive contamination, limit of tort compensation law and compensation amount, weight of medical evidence as well as role of expert witnesses, and related comparative legal studies.

Effect of prolonged radiation exposure on the thyroid gland of residents living in 60Co-contaminated rebar buildings.

PURPOSE: To evaluate prolonged low dose-rate gamma-exposure effects on the thyroid glands of residents living in 60Co-contaminated steel buildings. MATERIALS AND METHODS: Physical examination and ultrasonography of the thyroid, determination of thyroid function and anti-thyroid microsomal antibodies were performed for 1346 residents. Ultrasound-guided aspiration cytology was done for thyroid nodules. The study subjects were stratified by age at examination (< or = 15 and > 15 years), sex and exposure dose to the body. Dose-response data on the prevalence of various thyroid diseases were analysed by the multiple logistic regression analysis. RESULTS AND CONCLUSIONS: The prevalence of simple goitre was related to the exposure with a dose-response relationship for males of all ages, and for females of < or = 15 years. There was a biological gradient of thyroid cyst prevalence with the increase in exposure dose for females of all ages. The prevalence of elevated serum tri-iodothyronine level showed a dose-response relationship for males of < or = 15 years. A significant increase in thyroid abnormalities with dose was observed for males of all ages, and for females of < or = 15 years.

Biodosimetry using chromosomal translocations measured by FISH in a population chronically exposed to low dose-rate 60Co gamma-irradiation.

PURPOSE: To evaluate the cumulative gamma-radiation personal exposure by analysing lymphocyte chromosome translocations using FISH painting and to compare FISH-derived biodoses with those derived from retrospective physical dose reconstruction in residents receiving chronic low dose-rate gamma-irradiation while living in radio-contaminated buildings. MATERIALS AND METHODS: Chromosome translocation frequencies were evaluated by scoring 933 to 3077 metaphases under fluorescence microscope for each of the five male and four female exposed individuals after they had relocated from the radioactive environment for 34-82 months. FISH painting was conducted using kits of whole-chromosome probes for chromosomes 1, 2 and 4 in orange and 3, 5 and 6 in green and counter-stained with 4',6-diamidino-2-phenylindole (DAPI). The retrospective dose estimation termed Taiwan Cumulative Dose (TCD) was conducted by assessment using detailed information of historical exposure and the environmental radioactivity for each apartment during previous residency. RESULTS: A total of 20 244 well-prepared metaphases were scored. Biodoses were calculated from the translocation frequencies and physical doses were estimated from detail questionnaires for each individual. The translocation frequencies measured ranged from 2.2x10(-3) to 26.8x10(-3) translocations per cell and the dose equivalent from 52.2 to 992.2mSv. A good correlation was observed between the physical and biodoses. A plot of TCD against FISH-derived doses produced D(fish) =0.65 D(TCD), when fitted by a linear model, and D(fish) = 0.53 D(TCD)+ 1.26x10(-4 ) D(2)(TCD), when fitted with a linear-quadratic model. Given the scatter in the data and the extremely small quadratic dose contribution, neither model could be ruled out. CONCLUSION: Chromosome translocations provide a valid method of dose estimation in extremely protracted low dose-rate gamma-radiation exposure. Validation of the TCD method by FISH-measured translocations supports the use of TCD for epidemiological studies.

Unusual 232Th and 238U contamination on some road surfaces in Taoyuan, Taiwan.

At least eight bustling streets or approximately 3-5% of all the road surface of civilian utility in the downtown area of Taoyuan City, Taiwan, were inadvertently found to contain unusual levels of radioactivity during a routine environmental radiation surveillance in mid-1994. Crushed rock debris and coarse sands separated from the asphalt pavement were identified to be the source of excessive radioactivity. By employing gamma spectrometry, we have measured 232Th activity (via 228Ac) and mU activity (via 214Bi) in some of the samples to be up to about 4,000 and 1,000 Bq kg(-1), respectively. The dose rate on the road surface reached about 1.3 microSv h(-1), as compared with the background level of 0.08 microSv h(-1) in much of Taiwan. This unusual radioactivity was due to accidental mixing of road construction materials with materials enriched 232Th and 238U.

Lenticular opacities in populations exposed to chronic low-dose-rate gamma radiation from radiocontaminated buildings in Taiwan.

Chen, W-L., Hwang, J-S., Hu, T-H., Chen, M-S. and Chang, W. P. Lenticular Opacities in Populations Exposed to Chronic Low-Dose-Rate Gamma Radiation from Radiocontaminated Buildings in Taiwan. Radiat. Res. 156, 71-77 (2001). Epidemiological and experimental studies have revealed the cataractogenic potential of large acute doses of radiation. However, studies on the dose-response effect and the incidence of lenticular changes after exposure to chronic low doses of radiation have seldom been conducted. To evaluate quantitatively the lenticular changes in a population exposed to chronic low-dose-rate gamma radiation in their daily living or school environment in steel buildings contaminated with (60)Co in Taiwan, a total of 114 exposed individuals participated in a thorough ophthalmological examination in 1998. The lenticular opacities were evaluated by slit-lamp biomicroscopy after full pupil dilatation and were scored by the Lens Opacities Classification System III (LOCS III) and a modified subclinical minor lenticular focal defects system. These individuals were further divided into those less than 20 years old, those between 20 and 40 years old, and those more than 40 years old to evaluate the effects of age. The cumulative doses were assessed for each individual using the Taiwan Cumulative Dose (TCD) estimation system. A significant dose-dependent increase in the numbers of focal lens defects in those less than 20 years old was demonstrated, while less significant changes were observed in the other two age groups or by the LOCS III scoring. Results suggested that chronic low-dose-rate irradiation might induce minor lenticular changes, especially in lenses of young subjects. The delayed clinical changes in these young exposed subjects warrants further long-term follow-up.

A dose reconstruction of 60Co-contaminated window frames in a Taiwanese school.

Since 1992, hundreds of buildings in Taiwan were discovered to have 60Co contamination in the structural rebar. The contamination resulted from improper handling of 60Co-contaminated scrap metal in 1982 and 1983, which subsequently was recycled and used throughout Taiwan. Hsin-hsin Kindergarten school enrolled about 600 students over the 10-y period before the contamination was discovered. Hsin-hsin Kindergarten had three 60Co-contaminated steel window frames with measured dose rates on contact up to 150 microSv h(-1). In this study, a range of potential doses received by the Hsin-hsin Kindergarten students were estimated using ISOSHLD dose modeling software. ISOSHLD is a rapid, inexpensive screening tool to reconstruct dose ranges. To assess the potential risks to habitants of the school for the first year after construction, calculated dose rate ranges of 0.08 microSv h(-1) to 75.38 microSv h(-1) were then applied to the International Commission [corrected] on Radiation Protection 60 nominal detriment coefficients for stochastic effects. Risk estimates ranged from 1.46 x 10(-4) to 7.42 x 10(-4) excess fatal cancers per lifetime.

Determination of 8-oxoguanine in individual cell nucleus of gamma-irradiated mammalian cells.

8-Oxoguanine, through its ability to mispair bases other than cytosine, is assumed to be one of the most potent premutagenic lesions in nuclear DNA damaged by reactive oxygen radicals. In this study, we examine whether the presence of residual 8-oxoguanine can be detected in mammalian cells after exposure to ionizing radiation. MOLT-4 human leukemia cells and CHO-K1 Chinese hamster cells were acutely irradiated in vitro with 0, 0.2, 0.4, 0.6 and 1.0 Gy gamma radiation at room temperature. The amounts of 8-oxoguanine and total DNA in the cell nucleus were detected by fluorescein-isothiocyanate (FITC)-labeled avidin, which binds specifically and directly to 8-oxoguanine, and propidium iodide, respectively. The intensity ratios between these two fluorescent dyes were then taken as indices to measure the content of 8-oxoguanine within individual cells. We found an apparent dose-dependent increase in the amount of 8-oxoguanine accumulated in cells of both lines. Moreover, the content of 8-oxoguanine decreased from 2 to 20 h after irradiation in CHO-K1 cells, which may reflect the time-dependent repair processes at the 8-oxoguanine lesions. This novel approach may provide a sensitive tool for in situ measurement of 8-oxoguanine in cells or even in the human body after exposure to ionizing radiation.

Distribution of 137Cs in soil along Ta-han River Valley in Tau-Yuan County in Taiwan.

Environmental 137Cs contamination was suspected from accidents at spent fuel storage pits of a research reactor site in the Ta-han River valley in Taiwan. In order to further characterize this contamination, soil samples were collected and measured by a gamma-spectroscopy system in 1999. It was found that 137Cs contamination is distributed up to 4 km from the reactor in an area covered mostly by rice and plant fields. 137Cs concentration in the topsoil ranged up to about 1000 Bq kg-1, as compared with soil beyond the contaminated area, which does not exceed 15 Bq kg-1. Spatial distribution of 137Cs was characterized by strong non-uniformity, which complicated our understanding of the distribution pathway of the radionuclides. The highest concentrations of 137Cs, up to more than 1000 Bq kg-1, were found within a few rice fields. The relative location of these rice fields and the water supplies from local streams suggested that the 137Cs was distributed along water pathways in the valley.

Dynamics of changes in micronucleus frequencies in subjects post cessation of chronic low-dose radiation exposure.

To assess DNA damage remaining in peripheral lymphocytes, 48 individuals were evaluated twice for lymphocyte micronucleus frequencies by the cytokinesis-blocking cytochalasin B (CBMN) analysis post relocation from radio-contaminated apartments after various periods of time. The frequencies of CBMN at the first evaluation were significantly higher than those at the second examination (Chang et al., 1999c). These individuals were categorized into three groups: those with cumulative exposure of >300 mSv (defined as high exposure, HDose), those with 100-300 mSv (MDose) and those with <100 mSv (LDose). Using the Poisson mixed-effect model (Little et al., 1996), the estimated mean CBMN frequencies ( per thousand) for individuals in HDose, MDose and LDose exposure categories when they had only recently relocated were 21.8, 17.6 and 15.4, respectively. The estimated mean duration post relocation for the CBMN frequencies of these individuals to reduce to 10.2, the second CBMN frequency, on average, was 47.5, 37.2 and 28.3 months in the three exposure groups, respectively. The rates of change in CBMN frequencies were shown to be significantly higher in the HDose group than in the MDose and LDose groups. The results suggested a characteristic dose-dependent decline in the CBMN frequencies in the exposed population post cessation of chronic low-dose ionizing radiation exposure.

Physical heights of children with prolonged low dose-rate gamma-radiation exposure in radiocontaminated buildings.

PURPOSE: To evaluate low dose-rate radiation effects on the physical heights of children staying in apartments with 60Co-contaminated steel construction. MATERIALS AND METHODS: Children who once resided in radiocontaminated apartments since early 1983 were examined for height and body weight status from age 1 month to 18 years and before they moved out of the apartments. The physical heights and body weights of 21 898 age- and sex-matched non-exposed children from a nationwide school surveillance in 1997-98 were taken as controls. The physical height data were shown as height percentiles (HP) compared with reference children and age-specific relative height differences (RHD). RESULTS: HP and RHD in 48 exposed boys and 37 girls were analysed using generalized estimating equations (GEE), which accounted for multiple measurements and correlation between these measurements in the same individuals during this period. After adjusting for effects from parental heights and body mass index (BMI), clear dose-related decreases in HP and RHD were observed in the exposed boys with a cumulative exposure > 60 mSv. CONCLUSIONS: Prolonged low dose-rate y-radiation exposure was associated with adverse effects on the physical heights of growing boys, but were less apparent in the exposed girls.

HUman MicroNucleus project: international database comparison for results with the cytokinesis-block micronucleus assay in human lymphocytes: I. Effect of laboratory protocol, scoring criteria, and host factors on the frequency of micronuclei.

Micronucleus (MN) expression in peripheral blood lymphocytes is well established as a standard method for monitoring chromosome damage in human populations. The first results of an analysis of pooled data from laboratories using the cytokinesis-block micronucleus (CBMN) assay and participating in the HUMN (HUman MicroNucleus project) international collaborative study are presented. The effects of laboratory protocol, scoring criteria, and host factors on baseline micronucleated binucleate cell (MNC) frequency are evaluated, and a reference range of "normal" values against which future studies may be compared is provided. Primary data from historical records were submitted by 25 laboratories distributed in 16 countries. This resulted in a database of nearly 7000 subjects. Potentially significant differences were present in the methods used by participating laboratories, such as in the type of culture medium, the concentration of cytochalasin-B, the percentage of fetal calf serum, and in the culture method. Differences in criteria for scoring micronuclei were also evident. The overall median MNC frequency in nonexposed (i.e., normal) subjects was 6.5 per thousand and the interquartile range was between 3 and 12 per thousand. An increase in MNC frequency with age was evident in all but two laboratories. The effect of gender, although not so evident in all databases, was also present, with females having a 19% higher level of MNC frequency (95% confidence interval: 14-24%). Statistical analyses were performed using random-effects models for correlated data. Our best model, which included exposure to genotoxic factors, host factors, methods, and scoring criteria, explained 75% of the total variance, with the largest contribution attributable to laboratory methods.