Development of the negative ion beams relevant to ITER and JT-60SA at Japan Atomic Energy Agency

In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications.

Development of design technique for vacuum insulation in large size multi-aperture multi-grid accelerator for nuclear fusion

Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators for fusion application. In this method, the nested multi-stage configuration of the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages was based on the previous experimental results about the area effect and the multi-aperture effect. Since the multi-grid effect was found to be the extension of the area effect by the total facing area this time, the total voltage holding capability of the multi-stage can be estimated from that per single stage by assuming the stage with the highest electric field, the total facing area, and the total apertures. By applying these consideration, the analysis on the 3-stage MAMuG accelerator for JT-60SA agreed well with the past gap-scan experiments with an accuracy of less than 10% variation, which demonstrated the high reliability to design MAMuG accelerators and also multi-stage high voltage bushings.

A novel metabolic activation associated with glutathione in dimethylmonothioarsinic acid (DMMTA(V))-induced toxicity obtained from in vitro reaction of DMMTA(V) with glutathione

The purpose of the present study was to elucidate the metabolic processing of dimethylmonothioarsinic acid (DMMTA(V)), which is a metabolite of inorganic arsenic and has received a great deal of attention recently due to its high toxicity. The metabolites produced from an in vitro reaction with GSH were analyzed by high performance liquid chromatography-time of flight mass spectrometer (HPLC-TOFMS), HPLC with a photodiode array detector (PDA), and also gas chromatography-mass spectrometry (GC-MS) and GC with a flame photometric detector (FPD). The reaction of dimethylarsinic acid (DMA(V)) with GSH did not generate DMA(V)-SG but did generate dimethylarsinous acid (DMA(III)) or DMA(III)-SG. On the contrary, we confirmed that the reaction of DMMTA(V) with GSH directly produced the stable complex of DMMTA(V)-SG without reduction through a trivalent dimethylated arsenic such as DMA(III) and DMA(III)-SG. Furthermore, the present study suggests the production of hydrogen sulfide (H2S) and dimethylmercaptoarsine (DMA(III)-SH), a trivalent dimethylated arsenic, as well as DMA(III) and DMA(III)-SG in the decomposition process of DMMTA(V)-SG. These results indicate that the toxicity of DMMTA(V) depends not only on the formation of DMA(III) but also on at least those of H2S and DMA(III)-SH.

Associations between estrogen receptor genetic polymorphisms, smoking status, and prostate cancer risk: a case-control study in Japanese men

OBJECTIVE

Prostate cancer (PCa) is one of the major causes of death among men. Our study investigated the association of ESR1 and ESR2 genotypes with susceptibility to PCa in relation to smoking status in Japanese.

METHOD

A case-control study was performed with 750 Japanese prostate cancer patients and 870 healthy controls. After age-matching in case-controls, 352 controls and 352 cases were enrolled in this study. By using logistic regression analysis, the different genotypes from ESR1 and ESR2 were analyzed according to case/control status.

RESULT

ESR2 rs4986938 AG and AG + AA genotypes were associated with significantly decreased risk of PCa (AG: OR = 0.68, 95 % CI 0.47-0.97, P < 0.05 and AG + AA: OR = 0.67, 95 % CI 0.47-0.94, P < 0.05). However, there was no significant association between ESR1 rs2234693 and PCa risk. When patients were grouped according to smoking status, the ESR2 rs1256049 AA genotype (OR = 0.48, 95 % CI 0.25-0.95, P < 0.05) and ESR2 rs4986938 AG + AA genotype (OR = 0.64, 95 % CI 0.41-1.00, P < 0.05) showed significantly decreased PCa risk in the ever-smoker group.

CONCLUSION

Our results suggest that the estrogen receptor ESR2 has a very important function to predict PCa and that different SNPs have different predictive values. Smoking may influence estrogenic activity and may influence PCa together with the estrogen receptor.

Association of arteriosclerosis index and oxidative stress markers in school children

BACKGROUND

Recent years have seen increased numbers of children with conditions that contribute strongly to atherosclerotic disease, such as passive smoking, obesity, and dyslipidemia. In the present study, we evaluated the utility of non-invasive urinary markers in preventing lifestyle-related diseases by comparing lipid metabolism-related parameters with oxidative stress markers in school children.

METHODS

Subjects were 85 first-grade students. The variables examined included the smoking in subjects' household; exercise habits; height and weight; blood pressure; and plasma total cholesterol, high-density lipoprotein cholesterol, triglyceride, leptin, blood sugar, urinary cotinine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and 8-isoprostaglandin F2α (IsoP).

RESULTS

Of the subjects, 10.6% were obese (% overweight ≥ 20%), 3.5% had a high-risk arteriosclerosis index (AI; 3 ≤ AI < 5), and 29.4% were passive smokers. No significant differences were seen between boys and girls for any of the measurement parameters. Both urinary 8-OHdG (6.8-24.5 ng/mg creatinine) and IsoP (0.9-7.4 ng/mg creatinine) were detected in all subjects, and a significant positive correlation was seen between the two markers. On multiple regression analysis using AI as an objective variable and all non-invasive markers as explanatory variables, urinary IsoP correlated most strongly with AI (P ≤ 0.01).

CONCLUSIONS

Risk factors for atherosclerosis in adults, such as obesity and hypercholesterolemia, are associated with oxidative stress and inflammation. The present findings of the strongest correlation between urinary IsoP and AI suggest that urinary IsoP may serve as a non-invasive and effective early marker in predicting risk in children of developing lifestyle-related diseases.

Possible production of arsenic hemoglobin adducts via exposure to arsine

OBJECTIVES

Arsine is an arsenic compound generated as a by-product in metal refineries. Accidental poisoning occurs sporadically; however, the administrative level for workers has not been established. Thus, it is essential to identify a highly specific biomarker for risk management in the workplace. The aim of this study was to identify an arsenic adduct, a potential biomarker, in the plasma.

METHODS

Preserved mouse blood was exposed to arsine in vitro, and the plasma was separated. The residual clot of the control sample was hemolyzed using ultrapure water, and the supernatant was collected. Plasma from mice exposed to arsine in vivo was also separated from blood. Immunoprecipitation assays were conducted using all samples after ultrafiltration, and three fractions were collected. The total arsenic concentration in each fraction was quantified using inductively coupled plasma mass spectrometry (ICP-MS). The three in vitro samples and the eluate fraction from immunoprecipitation were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS).

RESULTS

In the exposed samples, the arsenic concentration in the fraction containing immunocomplexes was higher when immunoprecipitation was conducted with an anti-globin antibody. Three peaks were specifically observed in arsine-exposed samples after MALDI-TOF-MS analysis. Two of them were around m/z 15,000, and the other was m/z 15,700. The latter peak was confirmed even after immunoprecipitation.

CONCLUSIONS

Globin forms an adduct with arsenic after both in vitro and in vivo exposure to arsine. This adduct together with hemoglobinuria could be a candidate biomarker of acute arsine poisoning in plasma.

Relation between cotinine in the urine and indices based on self-declared smoking habits

OBJECTIVES

The reliability of surveys on smoking habits based on questionnaires was investigated, using the urinary cotinine content as an objective index.

METHODS

The subjects tested were 2,849 office workers of middle age, who responded to questions concerning their smoking status, and also their urinary cotinine was measured by the HPLC method.

RESULTS

The boundary value between smokers and non-smokers, determined by the histogram independent of the questionnaire, was 63.1 and 79.4 ng/mg of creatinine for males and females, respectively. The rate of misclassification of the non-smokers and former smokers as smokers was 1.3% for males and 1.8% for females, whereas that of current smokers as non-smokers was 6.3% and 2.1%. We also assessed the effect of smoke inhalation on the urinary cotinine value, and found a significant difference for males in the cotinine value by the presence of inhalation and also its depth.

CONCLUSIONS

The rate of misclassification in this study was considered to be comparatively low. Several studies have also assessed the reliability of the questionnaire on smoking habits, and found different misclassification rates, indicating the dependence on the race and number of subjects tested. To our knowledge, there were only a few surveys on smoking among large groups, particularly in Japan, such as this one, therefore the results obtained in this study are meaningful.

Common variants at 11q12, 10q26 and 3p11.2 are associated with prostate cancer susceptibility in Japanese

We have previously reported multiple loci associated with prostate cancer susceptibility in a Japanese population using a genome-wide association study (GWAS). To identify additional prostate cancer susceptibility loci, we genotyped nine SNPs that were nominally associated with prostate cancer (P < 1 × 10(-4)) in our previous GWAS in three independent studies of prostate cancer in Japanese men (2,557 individuals with prostate cancer (cases) and 3,003 controls). In a meta-analysis of our previous GWAS and the replication studies, which included a total of 7,141 prostate cancer cases and 11,804 controls from a single ancestry group, three new loci reached genome-wide significance on chromosomes 11q12 (rs1938781; P = 1.10 × 10(-10); FAM111A-FAM111B), 10q26 (rs2252004; P = 1.98 × 10(-8)) and 3p11.2 (rs2055109; P = 3.94 × 10(-8)). We also found suggestive evidence of association at a previously reported prostate cancer susceptibility locus at 2p11 (rs2028898; P = 1.08 × 10(-7)). The identification of three new susceptibility loci should provide additional insight into the pathogenesis of prostate cancer and emphasizes the importance of conducting GWAS in diverse populations.

Vacuum insulation of the high energy negative ion source for fusion application

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of ∼2 m(2). The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D(-) ion beams for 100 s.

The effect of sleep restriction and psychological load on the diurnal metabolic changes in tryptamine-related compounds in human urine

OBJECTIVE

The effect of a severely stressful situation (sleep restriction and psychological load) on the diurnal changes in novel tryptamine-related compounds (hydroxydiacetyltryptamine, sulphatoxymelatonin, and dihydromelatonin) was evaluated in human subjects for 16 days.

METHODS

The subjects were allowed to sleep for 5 h on days three through 12 and for 8 h on the other days. On days three through 12, the subjects were asked to perform a psychological task. The first two and the last 4 days were viewed as control days. A performance test was administered to evaluate the extent of the subjects' fatigue. Total urine was sampled by collecting it into bottles three times a day [(1) during the sleeping period, (2) in the morning, and (3) in the afternoon]. Seven tryptamine-related compounds in urine were assayed using HPLC-fluorometry.

RESULTS

The urine melatonin level was high at night and low during the day. In contrast, urinary levels of hydroxydiacetyltryptamine and sulphatoxydiacetyltryptamine were low at night and high during the day. Dihydromelatonin was undetectable in urine during the sleeping period. Sleep restriction and psychological load did not affect diurnal changes in urinary melatonin, hydroxydiacetyltryptamine, sulphatoxydiacetyltryptamine, or N-acetylserotonin levels. The concentrations of hydroxymelatonin and sulphatoxymelatonin in urine did not show diurnal changes and decreased gradually during the experimental days. A principal component analysis confirmed the diurnal changes and suggested two novel metabolic pathways: (1) N-acetylserotonin to sulphtoxydiacetyltryptamine via hydroxydiacetyltryptamine, and (2) melatonin to dihydromelatonin.

CONCLUSION

Severely stressful situations did not affect diurnal changes in melatonin, hydroxydiacetyltryptamine, sulphatoxydiacetyltryptamine, or N-acetylserotonin levels in urine.

Occupational exposure in methyl bromide manufacturing workers: 17-year follow-up study of urinary bromide ion concentration for biological monitoring

To elucidate the circumstances of their occupational exposure to methyl bromide (MeBr), we conducted a 17-yr study on 124 workers employed by a MeBr manufacturer. Subjects were classified into three groups according to the nature of their work: synthesis group, filling group, and other group. Urinary concentrations of bromide ion (Br(-)) were assessed, and data attained via MeBr-health examinations were analyzed. The highest Br(-) concentrations were seen in the synthesis group, with a median value of 13.0 μg/mg CRE (2.5-51.8), followed by the filling group, with a concentration of 11.9 μg/mg CRE (3.1-34.8). Both values were significantly higher than the levels noted in the other group (p<0.001). Three major opportunities for exposure were identified: during exchange of reaction equipment for maintenance or cleaning, during operations to adjust for weight variations after filling canisters, or when canisters were recycled. Overall, however, the workplace environment concentration remained largely below the administrative control level throughout the study period. Therefore, while this was a relatively well-controlled workplace, exposure opportunities still arose when performing certain tasks, indicating the need for ongoing improvement in workplace procedures and underscoring the importance of biological monitoring.

Passive smoking is associated with lower serum HDL-C levels in school children

BACKGROUND

In recent years, a number of studies have reported that exposure to environmental tobacco smoke (ETS) reduces high-density lipoprotein cholesterol (HDL-C) levels in children, as well as in adults. Further, a number of countries have indicated that passive smoking increases the risk of early arteriosclerosis onset. Here, to evaluate the effects of ETS exposure, we conducted a cross-sectional epidemiological study on primary school children in Japan using answers from a questionnaire survey, as well as urine cotinine and lipid metabolism-related variable measurements.

METHODS

A total of 121 sixth-grade primary school children participated in this study by completing a questionnaire about their food intake, lifestyle and family smoking habits. Early in the morning, we also measured height, weight, blood pressure, serum levels of total cholesterol, triglyceride, HDL-C, and blood sugar, as well as urine levels of cotinine and creatinine under unfed conditions.

RESULTS

From the questionnaire, 40 and 81 children reported being exposed and not exposed to ETS, respectively. Serum HDL-C levels, which were adjusted for the degree of corpulence and exercise habits, were significantly lower in the passive smoker group than the non-passive-smoker group (65.3 and 72.1 mg/dL, respectively; P= 0.012). In addition, proportional differences in serum HDL-C levels were also observed based on the amount of cigarettes smoked at home by family members of the child.

CONCLUSIONS

Results suggest that ETS exposure at home is associated in a dose-related manner with lower serum HDL-C levels in primary school children. In addition, our results suggest that smoking in the presence of children who are not usually exposed to ETS increases the risk of arteriosclerosis. Given these findings, we strongly recommend the establishment of anti-passive-smoking measures.

[Questionnaire survey of workers in specific buildings regarding multiple chemical sensitivity]

OBJECTIVES

The purpose of this study was to investigate the incidence of multiple chemical sensitivity (MCS) and effectiveness of the Quick Environment Exposure and Sensitivity Inventory (QEESI) in Japanese workers in specific buildings.

METHODS

The survey was performed in 2004-2006 in Japan. QEESI (Japanese version) and a checklist on accumulation of fatigue developed by the Ministry of Health, Labour and Welfare were used in the examination of 410 workers in specific buildings. Three criteria of QEESI's "symptom severity", "chemical intolerance", and "other intolerance" were evaluated in this study. Clinical histories were also surveyed.

RESULT

Responses were obtained from 368 (89.8%) workers. The results showed that 132 (35.9%) individuals have been diagnosed as having allergy. Only two (0.5%) individuals were found to be MCS patients. There was no sick building syndrome patient. Applying the "high" criteria with QEESI to the standard of Miller and Ashford, we determined that only four (1.1%) individuals met all the three criteria, and 17 (4.6%) individuals met two of the three criteria. The QEESI score of allergy persons was higher than that of nonallergy persons. Among nonallergy persons, those who have a high score on accumulation of fatigue in the checklist showed a high score in QESSI.

CONCLUSIONS

These findings indicated that the QEESI score tended to increase with workload and be high in individuals with allergy. Therefore, careful consideration is required, when QEESI is applied for screening MCS patients in Japan.

[Investigation of air pollution in a shopping center and employees' personal exposure level]

OBJECTIVES

To investigate the concentrations of chemicals found inside a shopping center (SC), we investigated the condition of air pollution in a SC and the personal exposure level of SC employees.

METHODS

The survey was performed in June 2006 in Kyushu. The chemicals studied were volatile organic compounds (VOCs) and aldehydes. The chemicals were collected by a personal passive sampler.

RESULT

Thirty-one VOCs and aldehydes were detected inside the SC. The results showed that the concentrations of all the chemicals detected in indoor air were less than those specified in the indoor air quality guideline of Ministry of Health, Labor and Welfare, Japan. The chemical concentrations in the SC decreased in the order of food corner > electric, clothing corner > outdoor and were clearly higher than those outdoors. Therefore, it is thought that the source of chemicals is indoors. The high indoor concentration of 2-ethyl-1-hexanol may be due to diffusion from the walls and floors. In addition, it is suggested that the personal exposure condition of the employees reflected the indoor concentration of each sales floor. The exposure level to formaldehyde was higher at nonworking time than at working time, suggesting that a larger exposure source exists in the place of residence than in the work place.

CONCLUSIONS

We found that indoor air quality in SC is maintained at good levels. This might be because of the Japanese strict regulations that require administrations of large-scale buildings to provide adequate ventilation and perform regular measurement of indoor air quality.

Genetic polymorphisms of human cytosol glutathione S-transferases and prostate cancer

Glutathione S-transferases (GSTs) are involved in the metabolism of a wide range of carcinogenic chemicals. In humans, cytosol GSTs are divided into eight classes: alpha (GSTA), mu (GSTM), pi (GSTP), theta (GSTT), tau (GSTZ), sigma (GSTS), omicron (GSTO) and kappa (GSTK). The allelic polymorphism of these enzymes is associated with variations in enzyme activity; hence, it may affect the concentration of activated carcinogenic chemicals in the body. In addition to the metabolism of chemical carcinogens, GSTs metabolize steroid hormones, compounds in the diet and other agents potentially involved in prostate carcinogenesis. Three genetic polymorphisms of GSTs, GSTM1*0 (null), GSTT1*0 (null) and GSTP1 A313G, have been well documented. No consistent associations between GSTM1, GSTT1 or GSTP1 genotypes and prostate cancer have been observed. Recent meta-analysis reports show that these polymorphisms of GSTM1, GSTT1 and GSTP1 are unlikely to be major determinants of susceptibility to prostate cancer.

Surface discharge related properties of fiberglass reinforced plastic insulator for use in neutral beam injector of JT-60U

Neutral beam injection (NBI) used for JT-60U is required to generate negative ions of 500 keV energies. To produce such high-energy ions, three-stage electrostatic accelerators consisting of three insulator rings made of fiberglass reinforced plastic (FRP) are applied. The surface discharges along FRP insulators are one of the most serious problems in the development of NBI. To increase the hold-off voltage against surface flashover events, it is necessary to investigate the FRP insulator properties related to surface discharges in vacuum. This paper describes surface flashover characteristics for FRP and alumina samples under vacuum condition. The results show that the fold-off voltages for FRP samples are inferior to those of alumina ceramics. In addition, measurement results of surface resistivity and volume resistivity under vacuum and atmospheric conditions, secondary electron emission characteristics, and cathodoluminescence under some keV electron beam irradiation are also reported. These are important parameters to analyze surface discharge of insulators in vacuum.

Molecular epidemiology and urothelial cancer

Tobacco smoking is the main cause of human urothelial cancer. It has been suggested that genetic susceptibility may contribute to the risk, because only a small portion of smokers develops urothelial cancer. Tobacco smoke contains many carcinogens which are activated or detoxified by phase-I or phase-II enzymes. The concentration of the ultimate carcinogen, which will react with DNA, is determined by the rate of activation and detoxification. Individuals with an increased rate of activation or a decreased rate of detoxification have a slightly higher level of bulky carcinogen-DNA adduct in the urothelial mucosa. Thus metabolic polymorphisms have been recognized as important determinants of carcinogen susceptibility, and recent efforts have shown that inter-individual differences in specific cytochrome P450 enzymes (CYPs), N-acetyltransferases (NAT), glutathione S-transferases (GST) and sulfotransferases (SULT) are often disproportionately represented in epidemiological studies between urothelial cancer cases and controls. It has been revealed that GSTM1 null genotype or NAT2 slow acetylator genotype may be associated with a small increase in urothelial cancer risk. Associations between other polymorphisms of metabolic enzymes and urothelial cancer are not well-known or are inconsistent. To reveal these associations, further well-designed and large-scale studies are needed.

Network-based analysis of calcium-binding protein genes identifies Grp94 as a target in human oral carcinogenesis

To characterise Ca(2+) -binding protein gene expression changes in oral squamous cell carcinomas (OSCCs), we compared the gene expression profiles in OSCC-derived cell lines with normal oral tissues. One hundred Ca(2+) -binding protein genes differentially expressed in OSCCs were identified, and genetic pathways associated with expression changes were generated. Among genes mapped to the network with the highest significance, glucose-regulated protein 94 kDa (Grp94) was evaluated further for mRNA and protein expression in the OSCC cell lines, primary OSCCs, and oral premalignant lesions (OPLs). A significant (P<0.001) overexpression of Grp94 protein was observed in all cell lines compared to normal oral epithelium. Immunohistochemical analysis showed highly expressed Grp94 in primary OSCCs and OPLs, whereas most of the corresponding normal tissues had no protein immunoreaction. Real-time quantitative reverse transcriptase-PCR data agreed with the protein expression status. Moreover, overexpression of Grp94 in primary tumours was significantly (P<0.001) correlated with poor disease-free survival. The results suggested that Grp94 may have potential clinical application as a novel diagnosis and prognostic biomarker for human OSCCs.

Differentiation of HAM/TSP from patients with multiple sclerosis infected with HTLV-I

OBJECTIVE

To better differentiate patients with human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) from patients with multiple sclerosis (MS) who are HTLV-I seropositive, we compared the HTLV-I antibodies and HTLV-I proviral DNA loads in CSF and peripheral blood mononuclear cells (PBMC).

METHODS

Intrathecal synthesis of HTLV-I antibodies and HTLV-I proviral DNA loads in CSF and PBMC were measured and compared in 39 Brazilian patients: 17 HAM/TSP and 22 HTLV-I-seropositive non-HAM/TSP (7 with other neurologic diseases, 11 asymptomatic carriers, and 4 HTLV-I-seropositive patients with an MS-like phenotype). In addition, we followed immunologic and virologic markers in comparison to the clinical course (by Kurtzke Expanded Disability Status Scale) of seven patients (five with HAM/TSP and two with an MS-like phenotype) for a mean period of 16 (SD +/- 5) months.

RESULTS

The proviral load in CSF and PBMC was higher in HAM/TSP than in non-HAM/TSP patients, except in the two HTLV-I-seropositive patients with an MS-like phenotype that also fulfilled the criteria for HAM/TSP. Higher HTLV-I proviral DNA load in CSF was associated with the higher proviral DNA load in PBMC and lower intrathecal synthesis of HTLV-I antibodies. These laboratory findings remained stable during follow-up.

CONCLUSION

The high proviral load in peripheral blood mononuclear cells or in CSF or both may be a good marker of human T lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and can differentiate patients with HAM/TSP from patients with multiple sclerosis infected with HTLV-I.

A cross sectional study of the respiratory health of workers handling printing toner dust

BACKGROUND

Although recent case reports have suggested possible respiratory effects of solid toner dust inhalation, this hypothesis has not been verified by epidemiological studies.

OBJECTIVES

To conduct a cross sectional study to evaluate the association between the biological indices of lung fibrosis and toner dust exposure in an occupational cohort handling solid toner dust in their work life.

METHODS

A total of 600 male toner workers and 212 control subjects were surveyed in terms of their subjective respiratory symptoms, pulmonary functions, and chest radiographic findings. In addition to the exposure history, the current working conditions and personal exposure levels to toner dust were also examined.

RESULTS

Although subjects handling toner for more than 20 years tended to show a higher prevalence of respiratory symptoms and minimal chest x ray abnormalities, there was no consistent relation between the exposure to toner dust and the biological responses of the respiratory system.

CONCLUSION

Deterioration of respiratory health related to toner dust exposure is less likely to occur in current well controlled work environments, especially if the powdered toner is handled carefully. Nonetheless, it is important to collect further epidemiological evidence on the biological effects of toner dust inhalation, preferably using a longitudinal study design.