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Biomedical subjects

A Andersen

Publications and source records attributed to A Andersen.

At least 19 recordsLinked to original sources
PubMed2001

Cancer incidence among workers in the Norwegian silicon carbide industry.

The presence of silicon carbide (SiC) fibers in the SiC smelter work environment has suggested a possible cancer hazard. The authors studied cancer incidence among 2,620 men employed for more than 6 months in three Norwegian SiC smelters. Follow-up from 1953 to 1996 revealed an overall excess risk of lung cancer (standardized incidence ratio = 1.9, 95% confidence interval (CI): 1.5, 2.3) and an elevated risk of stomach cancer (standardized incidence ratio = 1.5, 95% CI: 1.1, 2.0). Both standardized incidence ratio and Poisson regression analyses showed that lung cancer risk increased according to cumulative exposure to total dust, SiC fibers, SiC particles, and crystalline silica. The standardized incidence ratio for the upper SiC fiber exposure category was 3.5 (95% CI: 2.1, 5.6) when exposure was lagged by 20 years, while the Poisson regression analysis showed a rate ratio of 4.4 (95% CI: 2.1, 9.0). Smoking did not seem to be an important confounder. The excess risk of lung cancer may be explained by exposure to SiC fibers, but a strong correlation between the different exposures made it difficult to distinguish between them.

Adult↗
PubMed2001

Random matrix theory and acoustic resonances in plates with an approximate symmetry.

We discuss a random matrix model of systems with an approximate symmetry and present the spectral fluctuation statistics and eigenvector characteristics for the model. An acoustic resonator like, e.g., an aluminum plate may have an approximate symmetry. We have measured the frequency spectrum and the widths for acoustic resonances in thin aluminum plates, cut in the shape of the so-called three-leaf clover. Due to the mirror symmetry through the middle plane of the plate, each resonance of the plate belongs to one of two mode classes and we show how to separate the modes into these two classes using their measured widths. We compare the spectral statistics of each mode class with results for the Gaussian orthogonal ensemble. By cutting a slit of increasing depth on one face of the plate, we gradually break the mirror symmetry and study the transition that takes place as the two classes are mixed. Presenting the spectral fluctuation statistics and the distribution of widths for the resonances, we find that this transition is well described by the random matrix model.

Journal Article↗
PubMed2001

Risk of breast cancer among Norwegian women with visual impairment.

Experimental studies suggest that melatonin has a protective effect against breast cancer. Exposure to light suppresses melatonin secretion, but to a lesser degree in totally blind persons. Breast cancer was investigated in a cohort of 15 412 Norwegian visually impaired women. The risk among totally blind women was 0.64 (95% CI = 0.21-1.49, 5 cases only), and for those who became blind before age of 65, the SIR was 0.51 (95% CI = 0.11-1.49). Our findings give support to the 'melatonin hypothesis'.

Adolescent↗
PubMed2001

Effects of dose-intensive chemotherapy and radiotherapy on serum n-terminal proatrial natriuretic peptide in high-risk breast cancer patients.

By using N-terminal proatrial natriuretic peptide (proANP) in serum as a marker of cardiac function, we compared the cardiac side effects of two intensive adjuvant treatment regimens for breast cancer. Patients received either 9 cycles of FEC (5-fluorouracil, epirubicin and cyclophosphamide) where the doses of epirubicin and cyclophosphamide were escalated according to the leucocyte nadir (n = 49, FEC-group) or three cycles of FEC followed by high-dose chemotherapy with alkylating agents (n = 56, CTCb-group) given with the support of peripheral blood stem cells support. Both groups received adjuvant radiotherapy. Serial measurements of proANP were performed up to three years after treatment. Mean proANP values in the FEC-group was on average 19% higher than in the CTCb-group (p = 0.002). The proANP levels showed a significant association with the cumulative dose of epirubicin (p < 0.001) but not with cyclophosphamide (p = 0.151) and 5-FU (p = 0.160). The pharmacokinetics of epirubicin was studied at the first and third chemotherapy course. The proANP levels after treatment were significantly related to the AUC (p = 0.034) and Cmax(p = 0.037) of epirubicin. Left-sided chest irradiation was associated with on average 12% higher proANP values than right-sided (p = 0.031). We conclude that dose-escalated FEC causes a stronger increase in proANP than 3 FEC followed by high-dose CTCb-treatment. Increase of proANP levels might represent an early sign of cardiotoxicity secondary to chemotherapy and radiation treatment. Long-time follow-up is necessary to determine the clinical significance of these findings.

Adult↗
PubMed2000

Cancer incidence and cause specific mortality among workers in two Norwegian aluminum reduction plants.

BACKGROUND: Concern about the health hazards in the aluminum industry has initiated this study where we have investigated associations between exposure to polycyclic aromatic hydrocarbons (PAH) and fluorides, and cancer incidence and cause specific mortality among workers in two Norwegian aluminum plants in operation since 1954 and 1957, respectively. METHODS: The study was designed as a historical cohort study and comprised 5627 identified men employed for more than six months. Cancer incidence was investigated from start of employment to 1995, and cause specific mortality was investigated from 1962 to 1995. The observed cases of cancers and observed deaths were compared with expected numbers calculated from national rates. Internal comparisons were made using Poisson regression with age and smoking included in the models. Historical exposure to PAH and fluoride had been estimated previously by use of statistical modeling on industrial hygiene measurements and process parameters. A job exposure matrix was used to investigate possible associations between cumulative exposures, and cancer incidence and cause specific mortality. Smoking habits were identified for 92% of the cohort members. RESULTS: The study showed a significant excess risk for urinary bladder cancer among workers exposed to PAH, but no clear dose-response relationship. When using a 30-year lag period, a significant excess of bladder cancer in the highest exposure category (> 2000 microg/m(3);year PAH) was shown (SIR 4.08). The data also suggested an association between exposure to PAH and pancreatic cancer, but no association with lung cancer was seen. The mortality analysis indicated an association between exposure to pot-room emissions (fluorides) and mortality from chronic bronchitis, emphysema and asthma, but no associations with cardiovascular diseases. CONCLUSIONS: The study findings are compatible with an excess risk for bladder cancer for aluminum plant workers exposed to PAH. The increased risk for cancer of the pancreas indicated, should be further evaluated in larger exposed populations.

Aged↗
PubMed2000

Variability in methotrexate serum and cerebrospinal fluid pharmacokinetics in children with acute lymphocytic leukemia: relation to assay methodology and physiological variables.

Methotrexate (MTX) steady state concentrations were evaluated in 42 children who had received high-dose infusions (6-8 g/m2) for acute lymphocytic leukemia. Concentrations in serum and cerebrospinal fluid (CSF) measured by immunoassay were found to be highly variable. Reanalysis by a reference high-pressure liquid chromatography method ruled out analytical factors as a source of this variability. The correlation coefficient between the analytical methods was 0.77 for the serum data and 0.88 for the CSF data. The variability of serum and CSF concentrations was higher in younger patients (serum; P = 0.05 and CSF; P = 0.18), and the CSF concentration decreased with decreasing age and in later courses. Body surface area, body mass index, weight, and gender were not significantly related to MTX variability. We conclude that the pronounced pharmacokinetic variability seen during MTX infusions remains largely unexplained.

Antimetabolites, Antineoplastic↗
PubMed2000

Motor slowing and parkinsonian signs in aging rhesus monkeys mirror human aging.

Motor slowing is a universal feature of human aging, and parkinsonian signs are commonly expressed in human senescence. In the present study, age-associated declines in motor functions in 31 female rhesus monkeys were quantified by activity monitors and an automated test panel, and the incidence of parkinsonian signs was scored using a movement dysfunction assessment scale. Activity levels in middle-aged monkeys (12-17 years old) were less than half that of young animals (5-8 years old) and were further depressed in aged monkeys (21-27 years old). Movement dysfunction scores increased significantly with increasing age. Two or more parkinsonian signs were exhibited by 20% of the middle-aged monkeys and 36% of the aged monkeys. Slowing performance times on fine-motor hand tasks correlated significantly with increasing age. Motor learning was seen in all age groups, but improved faster in the young monkeys. The data suggest that aging rhesus monkeys provide an appropriate model to analyze the biological processes leading to motor slowing and the expression of parkinsonian signs in human senescence.

Aging↗
PubMed2000

Incidence of cancer among welders and other shipyard workers with information on previous work history.

The incidence of cancer among 4480 shipyard workers, including 861 welders, was investigated for a potential relationship between exposure to welding fumes and lung cancer. A subcohort of 3150 workers with information on previous work history was studied separately. This investigation is a historical prospective cohort study. Environmental air samples were collected in 1973, 1977, and 1989. Information on smoking habits was surveyed in 1976 and 1984. The employment work histories were collected from the personnel register. There were 411 observed cancers of all sites versus 387.5 expected, and 45 cases of lung cancer versus 51.3 expected. Nine cases of lung cancer were found among the welders versus 7.1 expected. Among 310 former seamen with welding experience, there was 1 case of lung cancer versus 2.1 expected. These shipyard workers showed no excess risk of lung cancer. Tobacco smoking and asbestos exposure are potential confounders in the study. There was no clear relationship between exposure to welding fumes and lung cancer, but welders with the longest experience had a relative risk of 1.9 for lung cancer. The differences in lung cancer incidence among the different shipyard workers could not be attributed to differences in recruitment patterns or previous work history.

Adolescent↗
PubMed2000

Incidence of cancer among workers exposed to vinyl chloride in polyvinyl chloride manufacture.

Based on results from two previous studies where an excess of melanomas was found in a cohort of workers exposed to vinyl chloride (VCM), a follow up of the incidence of cancer in the same cohort of 428 workers was carried out to scrutinize whether or not the excess could be confirmed by new cases. The total number of deaths in the study group from 1953 to the end of 1993 was 132 v 141 expected, and the total number of incident cancer cases was 56 v 57 expected. There were 11 cases of lung cancer v eight expected, seven cases of melanomas v 2.07 expected, and two cases of thyroid cancer v 0.34 expected. Five of the seven melanoma cases had occurred in the group that had been most heavily exposed to VCM v 0.7 expected. In the present follow up we also found five cases of the spinocellular cancer of the skin v 1.7 expected. Out of these five cases four were diagnosed after 1984. Two of the five cases v 0.7 expected had occurred in the most heavily exposed group. The total number of skin cancers (melanomas and spinocellular cancers) were 12 v 3.7 expected. There was one new case of melanoma between 1985 and 1993 v 0.7 expected. Hence, the strength of the relation between the observed and expected number of cases was reduced compared with the last follow up, and does not strengthen the previously indicated causal relation between exposure to VCM and development of malignant melanoma. There was no excess of testicular cancers in this study. The present results may indicate that occurrence of spinocellular skin cancer could bear some relation to work in the manufacture of polyvinyl chloride (PVC). Confirmation is needed from studies on other cohorts exposed to VCM.

Cohort Studies↗
PubMed2000

Lung and bladder cancer among workers in a Norwegian aluminium reduction plant.

OBJECTIVE: To investigate the relation between exposure to polycyclic aromatic hydrocarbons (PAHs) and the incidence of lung and bladder cancer among aluminium production workers. METHODS: The cohort comprised 1790 men employed for more than 5 years at a Norwegian aluminium plant contributing 36 587 person-years to the study. Historical exposure to PAHs was estimated by the use of industrial hygiene measurements and by a panel of three people familiar with the industry. Cancer incidence was investigated from 1953 to 1995. The observed cases of cancer among men were compared with expected numbers calculated from national rates for men, and dose-response relations were investigated by internal comparison by Poisson regression with age, period, smoking, and cumulative exposure included in the models. The effect of lagging exposure by 10, 20, and 30 years was also investigated. RESULT: The present study showed no increased risk of urinary bladder cancer or lung cancer with increasing cumulative exposure to PAHs. No significant changes in risk were found for different lag times. CONCLUSIONS: Due to the small size of this study, a minor increase in risk could not be excluded.

Adult↗
PubMed2000

Cancer incidence among male pulp and paper workers in Norway.

OBJECTIVES: The study investigated cancer incidence among 23,718 male pulp and paper workers employed continuously for at least 1 year between 1920 and 1993 in Norway. METHODS: The name, date of birth, personal identification number, dates of hire and termination for all employment periods, specific department, and job categories were registered for each worker. Six subcohorts were established (sulfite mill, sulfate mill, paper mill, maintenance department, administrative staff and other departments). Data on the cohort were linked with data in the Norwegian Cancer Register. The follow-up period for cancer incidence, date of death, or emigration was from 1953 through 1993. RESULTS: An excess incidence of lung cancer was found among both short- and long-term employees [standardized incidence ratio (SIR) 1.5, 95% confidence interval (95% CI) 1.13-2.03 and SIR 1.2, 95% CI 1.09-1.34, respectively], especially for workers with the longest latency (SIR 1.3, 95% CI 1.08-1.44) and for sulfite mill workers (SIR 1.5, 95% CI 1.09-1.99). The risk for pleural mesothelioma was also increased (SIR 2.4, 95% CI 1.45-3.75), especially among maintenance workers. The results also showed an increased risk for malignant melanoma (SIR 1.3, 95% CI 1.04-1.60), an unexpected finding. CONCLUSIONS: Almost all the increased risk for lung cancer can be explained by a combination of smoking habits and asbestos use. although an effect of other work-related exposures (sulfur and chloride compounds, wood dust) cannot be excluded. Most of the cases of pleural mesothelioma occurred in departments where asbestos was used. There is no clear explanation for the excess of malignant melanoma, and the finding may be a chance occurrence.

Adult↗
PubMed2000

Hormone-dependent cancer and adverse reproductive outcomes in farmers' families--effects of climatic conditions favoring fungal growth in grain.

OBJECTIVES: The impact of grain farming and climate on late-term abortion among female farmers, male genital birth defects among their sons, and hormone-dependent cancer among male and female farmers and their adult children was investigated. METHODS: National registers were cross-matched in Norway and 246,043 male and female farmers born in 1925-1971 were identified, as were their 264,262 children, born in 1952-1980, in agricultural censuses and in the population register. The subjects were followed in the Cancer Register through 1995. Farmers' births, conceived in 1973-1991, were identified, and the prevalences of late-term abortion in mothers and hypospadias and cryptorchidism in their sons at birth were examined. Exposure, defined as the combination of grain farming and categories of seasonal or cumulative warnings, was based on data in agricultural censuses and on local, seasonal, field fungal warnings. Estimated adjusted rate ratios or prevalence ratios served as the measures of association. RESULTS: Categories of high exposure were associated with reproductive outcomes and cancer among female farmers, the strongest occurring for late-term abortion (ratio 2.6, 95% confidence interval (95% CI) 1.6-4.3). Exposure associations for ovarian and breast cancer, and male genital defects, were more moderate. Endometrial cancer was associated with grain farming (ratio 2.0, 95% CI 1.4-2.8) across all levels of fungal warnings. Exposure associations for cancer were strongest for premenopausal, parous women. Exposure was not associated with cancer among male farmers or children. CONCLUSIONS: Climatic conditions favoring fungal growth in grain were associated with hormone-dependent adverse outcomes among female farmers; the results are consistent with hormonal effects of inhaled mycotoxins during pregnancy.

Abortion, Spontaneous↗
PubMed2000

Assessment of historical exposures in a nickel refinery in Norway.

OBJECTIVES: The aim of the study was, on the basis of new information on nickel species and exposure levels, to generate a specific exposure matrix for epidemiologic analyses in a cohort of Norwegian nickel-refinery workers with a known excess of respiratory cancer. METHODS: A department-time-exposure matrix was constructed with average exposure to total nickel estimated as the arithmetic mean of personal measurements for periods between 1973 and 1994. From 1972 back to the start of production in 1910, exposure concentrations were estimated through retrograde calculation with multiplication factors developed on the basis of reported changes in the metallurgical process and work environment. The relative distribution of water-soluble nickel salts (sulfates and chlorides), metallic nickel, and particulates with limited solubility (sulfides and oxides) was mainly derived from speciation analyses conducted in the 1990s. RESULTS: The average concentration of nickel in the breathing zone was < or = 0.7 mg/m3 for all workers after 1978. Exposure levels for smelter and roaster day workers were 2-6 mg/m3 before 1970, while workers in nickel electrolysis and electrolyte purification were exposed to concentrations in the range of 0.15-1.2 mg/m3. The level of water-soluble nickel was of the same order for workers in the smelting and roasting departments as in some of the electrolyte purification departments. CONCLUSIONS: Compared with earlier estimates, the present matrix probably offers a more reliable description of past exposures at the plant.

Air Pollutants, Occupational↗
PubMed2000

Cancer incidence among workers in six Norwegian aluminum plants.

OBJECTIVES: This study investigated associations between exposure to polycyclic aromatic hydrocarbons (PAH) and the incidence of lung, bladder, kidney, and pancreatic cancer among Norwegian aluminum plant workers. METHODS: Cancer incidence was investigated from 1953 to 1996 among 11,103 men employed for more than 3 years in the industry, giving 272,554 person-years during follow-up. A job exposure matrix was constructed to estimate exposure to particulate PAH and fluorides. The observed cases of cancer were compared with expected figures calculated from national rates. Dose-response relations were investigated by internal comparisons using Poisson regression and stratified analyses for standardized incidence ratio. Potential confounding by smoking was investigated in subanalyses restricted to 3 of the plants. RESULTS: The study showed an overall excess for bladder cancer, standardized incidence ratio 1.3 (95% confidence interval 1.1-1.5), which increased with increasing cumulative exposure to PAH and reached a relative risk of about 2 for the upper exposure category in the analysis with 30 years of lag time. There was no association between cumulative PAH exposure and lung cancer, but there were indications of an elevated risk of kidney cancer among the most heavily PAH-exposed persons in the analyses with a lag time of 30 years. For pancreatic cancer we found a higher incidence among the PAH-exposed persons than among the unexposed ones, but no clear dose-response association was found. CONCLUSIONS: The study showed an association between bladder cancer and exposure to PAH, but gave no support to an association between PAH exposure and lung cancer in the primary aluminum industry.

Aluminum↗
PubMed2000

Nonmalignant mortality among workers in six Norwegian aluminum plants.

OBJECTIVES: This study investigated the associations between exposure to fluorides and polycyclic aromatic hydrocarbons (PAH) and mortality from nonmalignant diseases among workers in the Norwegian primary aluminum industry. METHODS: Mortality among 10,857 men, employed for more than 3 years in 1 of 6 aluminum plants, was investigated from 1962 to 1996, giving 239,246 person-years during follow-up. Ajob-exposure matrix covering all 6 plants was used to estimate the individual exposure to total fluorides and particulate PAH. The observed cause-specific deaths were compared with expected figures calculated from national rates. Dose-response relations were investigated by internal comparisons using Poisson regression and by stratified analyses for standardized mortality ratio. Potential confounding by smoking was investigated in subanalyses restricted to 3 of the plants for which information on smoking habits was accessible. RESULTS: Mortality from circulatory disease was slightly lower than expected [SMR 0.95, 95% confidence interval (95%CI) 0.9-1.0], while there was an increased mortality from asthma, emphysema, and chronic bronchitis combined, SMR 1.2 (95% CI 1.0-1.5). Mortality from these diseases was associated with cumulative exposure to fluorides. The rate ratio in the internal analysis rose steadily to 2.5 (95% CI 1.5-4.3) for the upper exposure category. No association was observed between cumulative fluoride exposure or PAH exposure and circulatory mortality. CONCLUSIONS: The study showed an association between exposure to potroom emissions measured by fluorides and mortality from asthma, emphysema, and chronic bronchitis combined.

Aluminum↗
PubMed2000

Particle deposition in the nose related to nasal cavity geometry.

A number of studies have been made to characterise the deposition-pattern of inhaled airborne particles in the nose. Common to all results has been considerable differences in deposition fractions between normal human subjects. It was the aim of the current study to improve our understanding of individual differences in nasal deposition of inhaled particles. Depositions were measured in ten adult normal subjects and were related to dimensional measurements by acoustic rhinometry. Five litres of a polydisperse aerosol (MMAD = 0.7 micron, sigma g = 1.7) were inhaled through one nostril only during 5 inspirations with flows of 10, 20, and 30 L/min with decongested mucosa. Increasing flow was found to increase the fraction deposited in the nose, while there was an inverse correlation between nasal deposition fraction and minimum cross-sectional area of the nasal cavity (Amin). Information based on acoustic rhinometry measurements significantly reduced the amount of unexplained variation between subjects in nasal deposition fraction. We conclude that an estimate of maximum linear air velocity, calculated as airflow divided by Amin, was the best single predictor of nasal deposition fraction, which was found to increase with increasing air velocity raised to a power of approximately 4/3.

Adult↗