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Biomedical subjects

Y Thomassen

Publications and source records attributed to Y Thomassen.

At least 19 recordsLinked to original sources
PubMed2003

Intercommunity and temporal variation of eleven essential and five toxic elements in human placentas from deliveries in thirteen arctic and sub-arctic areas of Russia and Norway.

Research is described that constitutes an extension of an earlier paper (J. Environ. Monit., 2001, 3, 177-184), in which concentrations were measured in 263 human placentas of 11 essential elements (P, Ca, Mg, Cu, S, Na, Fe, Zn, K, Se, Mn) and 5 toxic elements (Ba, Sr, Pb, Ni, Cd). The additional data considered derive from earlier visits to 4 of the original 6 communities and 3 others, all but one of which are located in northern Norway and neighbouring areas of Russia. This more than doubled the number of placental samples available (263 to 571). Unfortunately, the personal, life-style and morphometric information obtained for the first study group was not available for the additional mothers. Country differences were evident for all elements except Ba, Fe and Zn; Cd, Cu, Mn, Na, Se, Ni, Pb, Sr and S were higher and K, P, Ca and Mg were lower in Russia (p < 0.03). Not unexpectedly, the highest median lead concentration was observed for the largest city in the western arctic region of Russia, namely Murmansk. Similarly, the higher median nickel level observed for Russia reflects the established observation that urinary nickel concentrations are higher in the Russian than in the Norwegian communities. Even though sampling was performed at different times of the year and before and after a 3-year interval in four centres, inter-collection differences were of relatively small magnitude and appear not to be linked to seasonal or temporal changes. Principal component analysis (PCA) confirmed the prominence of Factor 1, which grouped those metals that are known to form insoluble phosphate complexes and whose concentrations showed a dependence on gestational age and maternal smoking in the earlier study. It is concluded that PCA is a powerful statistical tool for exploring and identifying fundamental pathways and processes involved in governing the inorganic elemental composition of placental tissue. It also has the potential of identifying study limitations and quality assurance shortfalls. Further our findings show promise that placental concentrations of toxic elements may serve as an index of exposure and of nutritional intake for selected essential micro-elements.

Adult↗
PubMed2001

Neuropsychological effects of low mercury vapor exposure in chloralkali workers.

Neuropsychological effects were examined in 47 mercury vapor exposed male chloralkali workers with current low concentrations of urinary mercury (mean U-Hg 5.9 nmol/mmol creatinine (Cr)). Their average duration of exposure was 13.3 years, and the calculated mean concentration of U-Hg was 9.0 nmol Hg/mmol Cr per year (exposure intensity) during their time of exposure. They were compared with 47 age-matched male referents in a cross-sectional study. The two groups were not statistically significantly different with respect to neuropsychological test performance or number of self-reported subjective symptoms. The test results of the Static Steadiness Test, which assesses tremor, were not associated with exposure to mercury vapor. However current smokers had more hand tremor than non-smokers. Statistically significant associations were found between indices of current exposure (the concentration of inorganic mercury in whole blood) and the results of the WAIS Digit Symbol Test and the Benton Visual Retention Test (number of correct responses). This could indicate a small effect of current exposure on visuomotor/psychomotor speed and attention, and immediate visual memory. Whether the association found between the historical exposure intensity and the Digit Symbol Test results may represent long-term consequences of exposure cannot be determined in this study.

Adult↗
PubMed2001

Prophylactic iron supplementation in pregnant women in Norway.

In the present study 67 non-anaemic women were randomly allocated to either 100 mg or 15 mg iron daily at about the 10. week of pregnancy. At about week 18, 30 and 36 of pregnancy, as well as 6 weeks after delivery, hemoglobin and the serum concentrations of ferritin, vitamin B12, folates, Zn, Cu and Se were monitored. Dietary allowances of other minerals and vitamins are also increased in pregnancy, and the 15 mg iron tablet was enriched with Zn (10 mg), Cu (2 mg), Se (50 microg), vitamin B12 (3 microg), and folate (0.1 mg). Neither ferritin, nor Cu, Zn or Se concentrations differed statistically significantly between the treatment groups during pregnancy. Ferritin and Zn appeared to decrease approximately parallel to the hemodilution, whereas Cu concentrations increased from a non-pregnant reference mean of 18 micromol Cu/L to a maximum mean of nearly 33 micromol Cu/L during pregnancy. Se decreased concomitantly to about 1.0 micromol Se/L. Serum folate (around 15 micromol/L) was essentially unaffected by pregnancy in the group given multivitamin/mineral supplementation, whereas the mean concentration fell below 10 micromol/L in the group supplemented with 100 mg iron daily. Our results indicate that supplementation of 15 mg Fe daily during pregnancy results in a small reduction of hemoglobin. It is suggested that additional supplementation with folate might be of importance to maintain the serum folate concentration during pregnancy.

Adult↗
PubMed2001

Factor analysis of essential and toxic elements in human placentas from deliveries in arctic and subarctic areas of Russia and Norway.

Concentrations in human placenta of 11 essential elements (P, Ca, Mg, Cu, S, Na, Fe, Zn, K, Se, Mn) and 5 toxic elements (Ba, Sr, Pb, Ni, Cd) are compared for each of two arctic communities in eastern Norway and western Russia, and for another in each country located at more southerly latitudes. All but Mg, Fe, P and K were present in higher concentrations in the Russian study group. The observed inter-element correlations are reflected by the four major factors identified in a principal component analysis. The total variation explained was 67.3%, of which more than half (35.3%) was contributed by Factor 1. P, Ca, Mg, Ba, Sr, Pb, and Ni were major contributors to this factor. The placental concentrations of these elements depended strongly on gestational age, increasing from about week 35 and peaking near weeks 39 and 40, and exhibited skewed frequency distributions and a dependence on maternal smoking. The gestational-dependent mineralization of the placenta is interpreted to reflect the deposition of metal phosphates coinciding with smoking-induced tissue damage. The loadings of the remaining three factors are reviewed in the context of common uptake mechanisms, similar biochemistries and unique transport pathways. The inter-element relationships and grouping of the elements observed should constitute a scientific base for the use of placenta composition in environmental monitoring and epidemiological studies.

Adult↗
PubMed2001

Chemical speciation and sequential extraction of Mn in workroom aerosols: analytical methodology and results from a field study in Mn alloy plants.

Workers in the Mn alloy producing industry are exposed to aerosols containing a variety of Mn compounds (MnO, MnO,, Mn2O3, Mn3O4, FeMn and SiMn). This paper reports a novel four-step chemical speciation/ fractionation procedure developed for characterisation of workroom aerosols collected in Mn alloy producing plants. The following components of the aerosol have been quantified: "water soluble" Mn dissolved in 0.01 M ammonium acetate: Mn0 and Mn2+ dissolved in 25% acetic acid; Mn3+ and Mn4+ dissolved in 0.5%) hydroxylamine hydrochloride in 25%) acetic acid; and "insoluble" Mn digested in aqua regia and hydrofluoric acid. Dissolution of pure Mn compounds with well-defined stoichiometries were essentially complete in the respective leaching steps with detectable amounts of < 1% in others. Recoveries of a mixed quality control sample were also acceptable in the range 92-97% for the different oxidation states. The levels measured in the inhalable and respirable fractions in three Mn alloy producing plants were approximately 300 and 35 microg m(-3) of total Mn, respectively. The most obvious feature of the speciation results is that none of the work areas is characterised by a single Mn contaminant. The predominant oxidation states in the inhalable aerosol fraction are Mn0 and Mn2+ independent of job functions/departments. The occurrence of insoluble Mn compounds in both the inhalable and respirable aerosol fractions is significantly higher during production of SiMn.

Aerosols↗
PubMed2000

Determination of 1-(2-methoxyphenyl)piperazine derivatives of isocyanates at low concentrations by temperature-programmed miniaturized liquid chromatography.

A temperature-programmed packed capillary LC method with large-volume injection on-column focusing has been developed for screening and determination of 1-(2-methoxyphenyl)piperazine derivatives of airborne toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, hexamethylenediisocyanate and methylenebisphenyl-4,4-diisocyanate, based on sampling methods described in MDHS 25/3. Injection volumes up to 100 microl were successfully loaded onto the 250x0.32 mm I.D. capillary column packed with 3 microm Hypersil ODS particles. The isocyanate derivatives were loaded at 10 degrees C and eluted by a three-step temperature program starting at 10 degrees C for 10 min, followed by a temperature ramp of 2.5 degrees C min(-1) to 45 degrees C and then 9.9 degrees C min(-1) to 90 degrees C. The mobile phase consisted of acetonitrile-acetate buffer (3% triethylamine, pH 4.5) (45:55, v/v). The isocyanate derivatives were dissolved in acetonitrile-acetate buffer (3% triethylamine, pH 4.5) (30:70, v/v) to achieve sufficient focusing. The concentration limit of detection of the individual derivatives utilizing an "U" shaped flow cell with a 8.0 mm light path and an injection volume of 100 microl was 44, 87, 43 and 210 pg ml(-1) for toluene-2,6-diisocyanate, hexamethylenediisocyanate, toluene-2,4-diisocyanate and methylenebisphenyl-4,4-diisocyanate, respectively. Within the investigated concentration range, 10-500 ng ml(-1), the linear calibration curves gave correlation coefficients ranging from 0.994 to 0.998. The repeatability of the method with regard to retention time and peak height ranged from 0.3 to 1.1% and 1.1 to 2.3% (n=9) relative standard deviation, respectively. The average recovery of the method, with regard to toluene-2,4-diisocyanate, was 97.7+/-1.6% (n=9).

Chromatography, Liquid↗
PubMed2000

Neurobehavioral performance in aluminum welders.

METHODS: Twenty aluminum welders (mean age 33 years; range 21-52), who had been exposed to aluminum for an average of 8.1 years (range 2-21), were tested for tremor and reaction time and screened for neuropsychiatric symptoms in a cross-sectional study. The welders' median urinary aluminum concentration was 1.5 micromol/L (range 0. 7-4.8). Aluminum in air, measured inside the respiratory protection, was 0.9 mg/m(3) (range 0.6-3.8). The welders were compared with twenty construction workers matched for age. RESULTS: Welders reported more symptoms than referents did (median 2 vs. 1; P=0.047). Although the welders as a group performed better than the referents on a tremor test, years of exposure, but not age, was predictive of poorer performance. The welders' reaction times were rapid by clinical standards (mean simple reaction time (SRT): 221 milliseconds; mean continuous performance test (CPT): 364 milliseconds). Although, as a group, they performed better than the referents, there was a statistically significant relation between longer reaction times and aluminum in air (air-Al). CONCLUSIONS: The relations between hand steadiness and years exposed, and between reaction time and air-Al, could indicate slight effects from exposure to aluminum. The possibility of selection of workers with high manual skills into welding work and a possible job-related training effect, might partly serve to explain the good performance among the welders.

Adult↗
PubMed2000

Chemical composition of individual aerosol particles in workplace air during production of manganese alloys.

Aerosol particle samples were collected at ELKEM ASA ferromanganese (FeMn) and silicomanganese (SiMn) smelters at Porsgrunn, Norway, during different production steps: raw material mixing, welding of protective steel casings, tapping of FeMn and slag, crane operation moving the ladles with molten metal, operation of the Metal Oxygen Refinement (MOR) reactor and casting of SiMn. Aerosol fractions were assessed for the analysis of the bulk elemental composition as well as for individual particle analysis. The bulk elemental composition was determined by inductively coupled plasma atomic emission spectrometry. For individual particle analysis, an electron microprobe was used in combination with wavelength-dispersive techniques. Most particles show a complex composition and cannot be attributed to a single phase. Therefore, the particles were divided into six groups according to their chemical composition: Group I, particles containing mainly metallic Fe and/or Mn; Group II, slag particles containing mainly Fe and/or Mn oxides; Group III, slag particles consisting predominantly of oxidized flux components such as Si, Al, Mg, Ca, Na and K; Group IV, particles consisting mainly of carbon; Group V, mixtures of particles from Groups II, III and IV; Group VI, mixtures of particles from Groups II and III. In raw material mixing, particles originating from the Mn ores were mostly found. In the welding of steel casings, most particles were assigned to Group II, Mn and Fe oxides. During the tapping of slag and metal, mostly slag particles from Group III were found (oxides of the flux components). During movement of the ladles, most particles came from Group II. At the MOR reactor, most of the particles belonged to the slag phase consisting of the flux components (Group III). The particles collected during the casting of SiMn were mainly attributed to the slag phase (Groups III and V). Due to the compositional complexity of the particles, toxicological investigations on the kinetics of pure compounds may not be easily associated with the results of this study.

Aerosols↗
PubMed2000

Chemical composition of individual aerosol particles from working areas in a nickel refinery.

Individual aerosol particles (n = 1170) collected at work stations in a nickel refinery were analyzed by wavelength-dispersive electron-probe microanalysis. By placing arbitrary restrictions on the contents of sulfur and silicon, the particles could be divided into four main groups. Scanning electron images indicated that most of the particles examined were relatively small (< or = 2 microm, equivalent projected area diameter), and that their morphology suggested formation from a melt. There was an absence of well-defined phases and simple stoichiometries, indicating that exposures to pure substances such as nickel subsulfide or specific oxides appeared not to occur. Although the elemental composition of particles varied greatly, a rough association was evident with the known elemental content of the refinery intermediates. The implications of the findings for aerosol speciation measurements, toxicological studies and interpretation of adverse health effects are explored.

Aerosols↗
PubMed2000

The clinical expression of hemochromatosis in Oslo, Norway. Excessive oral iron intake may lead to secondary hemochromatosis even in HFE C282Y mutation negative subjects.

BACKGROUND: The prevalence of hereditary hemochromatosis in Norway is one of the highest reported in the world. However, the clinical presentation in patients with hemochromatosis in Norway seems to be different compared with recent studies elsewhere. The aim of this study was to investigate patients with hemochromatosis in one community hospital in Norway and to study the prevalence of the C282Y mutation. METHODS: One hundred and twenty patients were consecutively admitted to one medical department in Oslo. Serum transferrin and ferritin concentrations were measured in all patients, and a percutaneous liver biopsy was obtained in 108 of 120 (90%) patients. Stainable iron (Perls stain) in hepatocytes was graded from 0 to 4+ and fibrosis from 1 to 4. Genotyping for the C282Y and H63D mutation in the HFE gene was performed by PCR-RFLP. RESULTS: Forty-eight (40%) of the patients suffered from tiredness and astenia and 29 (24%) had typical arthropathy. Only 5 of 105 (4.5%) had biopsy confirmed cirrhosis and 5 had diabetes mellitus. Patients referred from a blood bank had significantly less symptoms and signs compared with other patients. Twenty-one of 120 (17.5%) patients were C282Y mutation negative. Seventeen (81%) of these patients (16 women and 1 man) had a history of extensive oral iron intake lasting from 5 to 50 years. When excluding those with extensive oral iron intake (n = 17), 92 of 103 (89%) were homozygous for the C282Y mutation, 7 (7%) were heterozygous including 3 compound heterozygous and 4 (4%) were mutation negative. CONCLUSIONS: Only a minority of our patients with hemochromatosis had a far advanced disease at the time of diagnosis (less than 5% had cirrhosis) and hemochromatosis in a majority of the C282Y mutation negative patients was associated with excessive oral iron intake for several years.

Adult↗
PubMed2000

Renal and immunologic markers for chloralkali workers with low exposure to mercury vapor.

OBJECTIVES: The aim of this study was to investigate renal function and immunologic markers among chloralkali workers with long-term low exposure to mercury vapor. METHODS: Forty-seven currently exposed workers were compared with reference workers matched for age in a cross-sectional design. RESULTS: The mean urinary mercury concentration was 5.9 (range 1.1-16.8) nmol/mmol creatinine (Cr) for the exposed workers and 1.3 (range 0.2-5.0) nmol/mmol Cr for the referents. The chloralkali workers had been exposed for an average of 13.3 (range 2.8-34.5) years. The activity of N-acetyl-beta-D-glucosaminidase in urine (U-NAG) was higher in the exposed workers (mean 0.18 U/mmol Cr versus 0.14 U/mmol Cr, P=0.02). Associations between current urinary mercury, cumulative urinary mercury, and cumulative urinary mercury per year (intensity) and U-NAG, autoantibodies to myeloperoxidase (anti-MPO) and proteinase 3 in serum, respectively, were observed. The activity of U-NAG and anti-MPO was increased in the workers with the highest exposure, as assessed by their mean intensity of exposure. The highest activity of U-NAG was observed in the exposed workers with the lower concentrations of selenium in whole blood. CONCLUSIONS: The study indicates an effect of exposure on the kidney proximale tubule cells, possibly modified by individual selenium status, and an effect mediated by neutrophil granulocytes.

Acetylglucosaminidase↗
PubMed1999

Critical evaluation of medical, statistical, and occupational data sources in the Kola Peninsula of Russia pertinent to reproductive health studies.

BACKGROUND: The feasibility study described herein was prompted by a report in 1992 of possible reproductive and developmental health concerns among female workers in a Russian nickel refinery. OBJECTIVE: The primary goal was to ascertain whether medical, statistical, and occupational data bases could be accessed for information about the pregnancy histories, occupational histories, and life-style factors of the women affected. METHODS: The project was facilitated by construction of a registry of all births in three towns with a nickel refinery and verification of its contents against patients' records obtained from hospital delivery and gynecology departments and community polyclinics. Municipal Registration Board, Regional Health Statistics Board, and nickel company records were also reviewed. RESULTS: Reproductive/developmental outcome information and workplace histories were acceptable. Sample-size calculations indicated that a cohort or cross-sectional study would be amenable and suitable for the detection of an excess risk for spontaneous abortion with adequate statistical significance and power. Such investigations would need to be supplemented by workplace environmental/biological monitoring assessments for evaluation of exposure to occupational hazardous factors and a worker's questionnaire to obtain information about life-style factors. A case-control design is recommended for the study of congenital defects. CONCLUSIONS: A well-designed, comprehensive epidemiology study is technically feasible because of the availability of a favorable pool of study subjects, reproductive/developmental outcome data, information to control for major confounders, and suitable occupational records.

Adult↗
PubMed1999

Characterisation of workers' exposure in a Russian nickel refinery.

In support of a feasibility study of reproductive and developmental health among females employed in the Monchegorsk (Russia) nickel refinery, personal exposure and biological monitoring assessments were conducted. The inhalable aerosol fraction was measured and characterised by chemical speciation and particle-size distribution measurements. Unexpected findings were that: (i), pyrometallurgical working environments had significant levels of water-soluble nickel; (ii), significant exposure to cobalt occurred for the nickel workers; (iii), particles of size corresponding to the thoracic and respirable fractions appeared to be virtually absent in most of the areas surveyed. The water-soluble fraction is judged to be primarily responsible for the observed urinary nickel and cobalt concentrations. It is concluded relative to current international occupational-exposure limits for nickel in air, and because of the high nickel concentrations observed in urine, that the Monchegorsk nickel workers are heavily exposed. The implication of this finding for follow-up epidemiological work is alluded to.

Adult↗
PubMed1999

Urinary nickel concentrations and selected pregnancy outcomes in delivering women and their newborns among arctic populations of Norway and Russia.

The two objectives of this study were to compare urinary nickel excretion in pregnant women and their newborns living in the Murmansk and Arkhangelsk Counties of Russia with that in comparable Norwegian populations living in Finnmark and the city of Bergen and to assess the influence on pregnancy outcome of different risk variables, specifically urinary nickel concentrations and questionnaire-based anamnestic information. Life-style information and urine samples were collected from 50 consecutive mother-infant pairs from hospital delivery departments in three Russian and three Norwegian communities. Pregnancy outcomes were verified from medical records. Urinary nickel excretion was significantly higher in the Russian communities, independent of the presence of a nickel refinery as a local environmental source. The birth weight and mean body mass index of the newborn children (BMIC) were significantly lower (p < 0.001) in the Russian groups, with or without adjustment for gestational age. A multivariate linear regression analysis indicated that maternal urinary nickel concentration had no impact on birth weight. The maternal body mass index (BMI) and maternal height were positive explanatory variables; maternal urinary creatinine is suggested as a weak negative factor. Smoking was shown to be a strong negative predictor only in the Norwegian group among whom there was a significantly higher smoking frequency (p = 0.005). The significant contribution of a country factor in the predictive model is interpreted to indicate that a number of important risk factors for low birth weight were not identified.

Adolescent↗
PubMed1999

Application of recent advances in aerosol sampling science towards the development of improved sampling devices: the way ahead.

This paper reviews the framework that underpins the development of a new generation of personal samplers capable of operating at much lower flowrates that those of the current generation and so capable of being used for exposure assessment not only for 'traditional' occupational populations (i.e., industrial workers) but also for people exposed to aerosols in the ambient atmosphere (including children). The opportunity for this new generation of samplers stems from the availability of very light and compact low-flowrate pumps. The development and deployment of such instruments presents: (a) physical challenges in terms of how to collect particle size fractions in a manner which is consistent with the new particle size-selective sampling criteria, and (b) analytical challenges in terms of how to quantitate the much smaller amounts of collected material that need to be analysed. The paper lays out the physical and analytical scenarios, and points the way forward to how such challenges can be overcome. Work is already in progress in several countries to develop prototype instruments for applications like those described.

Adult↗
PubMed1999

A study of exposure standards in Russia and the role of occupational hygiene.

This paper is the result of an investigation carried out in February 1997, which set out to learn about the development and application of occupational health standards, and in turn approaches to occupational environmental monitoring, in Russia, and to see how these were similar to, or different from, what takes place in other countries. The enquiry involved face-to-face meetings with senior Russian occupational health scientists and officials. It was confirmed that Russian occupational exposure standards are very stringent and provide a very high level of protection of workers. However, they are difficult to enforce, and it is suggested that the development of a strong and distinctive occupational hygiene discipline and profession in Russia would provide a "bridge" to enable more effective implementation and interpretation of those standards.

Guideline Adherence↗
PubMed1999

Correlation of urinary nickel excretion with observed 'total' and inhalable aerosol exposures of nickel refinery workers.

An investigation of the relationship between observed nickel aerosol exposures and urinary nickel excretion was undertaken at a Scandinavian nickel refinery. The goal of the study was to assess the impact of nickel aerosol speciation, the use of particle size-selective sampling instrumentation and adjustment of urinary levels for creatinine excretion on the usefulness of urinary nickel excretion as a marker for exposure. Urinary nickel measurements and paired 'total' and inhalable aerosol exposure measurements were collected each day for one week from refinery workers in four process areas. The mean observed urinary nickel concentration was 12 micrograms L-1 (11 micrograms of Ni per g of creatinine). The strongest relationships between urinary excretion and aerosol exposure were found when urinary nickel levels were adjusted for creatinine excretion and when exposure to only soluble forms of nickel aerosol was considered. No significant difference was observed between measures of 'total' and inhalable aerosol in the ability to predict urinary excretion patterns. In the light of these results, it is recommended that consideration be given to the chemical species distribution of nickel aerosol in the use of urinary nickel measurements as a screening tool for cancer risk in occupationally-exposed populations.

Adult↗