Siri M. Hetland

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.

Dust exposure assessed by a job exposure matrix is associated with increased annual decline in FEV1: a 5-year prospective study of employees in Norwegian smelters.

RATIONALE The relationship between dust exposure and annual decline in lung function among employees in the smelting industry is unknown. OBJECTIVES The aim of the study was to investigate the relationship between annual change in lung function and occupational dust exposure among workers in 15 Norwegian smelters. METHODS All employees (n = 2,620) were examined annually for 5 years (11,335 health examinations). At each examination spirometry was performed and a respiratory questionnaire was completed. The smelters were grouped as follows: (1) ferrosilicon alloys (FeSi) and silicon metal (Si-metal); and (2) silicon manganese (SiMn), ferromanganese (FeMn), and ferrochromium (FeCr). A job exposure matrix was available on the basis of 2,619 personal dust exposure measurements. The association between lung function expressed as FEV(1) and FVC per squared height (height(2)) and dust exposure was investigated using multivariate linear mixed model analyses. MEASUREMENTS AND MAIN RESULTS The annual change in FEV(1)/height(2) (deltaFEV(1)) related to dust exposure in the FeSi/Si-metal and SiMn/FeMn/FeCr smelters was -0.42 (95% confidence interval, -0.95 to 0.11) and -1.1 (-2.1 to -0.12) (ml/m(2)) x (mg/m(3))(-1) x year(-1), respectively. The annual decline in FEV(1)/height(2) was 1.6 ml/m(2) (0.15 to 3.1) steeper in smokers than in nonsmokers. The median geometric mean of the time-weighted dust exposure concentration levels of the employees was 2.3 mg/m(3) in the FeSi/Si-metal smelters and 1.6 mg/m(3) in the SiMn/FeMn/FeCr smelters. Among nonsmokers, deltaFEV(1) was -0.86 (-1.6 to -0.10) and -1.1 (-2.5 to 0.25) (ml/m(2)) x (mg/m(3))(-1) x year(-1) in the FeSi/Si-metal and SiMn/FeMn/FeCr smelters, respectively. Thus, for a 1.80 m tall employee the annual decline in FEV(1) associated with average dust exposure was 5.7 ml/year in the SiMn/FeMn/FeCr smelters, and 6.4 ml/year for a nonsmoker in the FeSi/Si-metal smelters. CONCLUSIONS In all smelters combined, the annual change in FEV(1) was negatively associated with increasing dust exposure. This association was also significant among workers in SiMn/FeMn/FeCr smelters and among nonsmokers in the FeSi/Si-metal smelters.

Decreased lung function among employees at Norwegian smelters

BACKGROUND In the smelting industry airborne pollutants are emitted into the workplace atmosphere during the production process. Our aim in this study was to investigate the relationship between production and lung function among employees at Norwegian smelters. METHODS Spirometry was performed on 3,924 employees, who also completed a standardized questionnaire. The employees were classified by job functions: (i) line operators were employed full-time on the production line, (ii) non-exposed employees did not work in production, and (iii) the remainder of the employees were classified as non-line operators. RESULTS The mean age of the participants was 38.6 (range 20.0-55.0) years, 88.5% were males. The multivariate analyses showed that, compared to the forced expiratory volume in one second (FEV(1)) in non-exposed employees, the FEV(1) (95% confidence interval) was 87 (33-141) ml and 65 (12-118) ml lower in line and non-line operators, respectively. The prevalence of airflow limitation (FEV(1)/forced vital capacity (FVC) below the 5th percentile of the predicted value) was 4.7% in non-exposed employees, 7.5% in non-line operators and 8.3% in line operators. CONCLUSION Compared with non-exposed employees, impairment of lung function among employees at Norwegian smelters was significantly related to the job categories of line operator and non-line operator.

Quantitative and Qualitative Assessment of Exposure among Employees in Norwegian Smelters

OBJECTIVES To generate a job exposure matrix (JEM) for dust exposure in Norwegian smelters to be used in an epidemiologic study of respiratory diseases and to identify determinants of exposure. METHODS The arithmetic mean and geometric mean (GM) of 2619 personal dust exposure measurements were applied in constructing the JEM, which was assigned to 2620 employees participating in a respiratory survey including yearly spirometry and a respiratory questionnaire. A qualitative exposure classification was constructed: (i) line operators were those employed full time in the production line, (ii) non-exposed employees were those who did not work in production and (iii) the remainder were classified as non-line operators. RESULTS In the ferrosilicon alloy and silicon metal production group (FeSi/Si-metal), the median GM of dust exposure was 2.3 mg m(-3) (0.04-5.6) (10-90% percentiles) compared with 1.6 mg m(-3) (0.02-2.3) in the silicomanganese, ferromanganese and ferrochromium production group (SiMn/FeMn/FeCr). Multivariate analyses showed that dust exposure concentration levels decreased significantly with increasing age (FeSi/Si-metal), was significantly lower in females than in males and was significantly higher in current smokers than in never-smokers. Dust exposure concentration levels were also higher in employees reporting previous exposure to dust, fumes and gases than in employees without such previous exposure, though, significant only in the FeSi/Si-metal production group. CONCLUSION The dust exposure levels of the employees were higher in the FeSi/Si-metal production group than in the SiMn/FeMn/FeCr production group. Age, gender, smoking status and previous exposure were significant determinants of dust exposure and should be evaluated in future analyses of the relationship between health outcomes and dust exposure in this industry.

Prevalence of airflow limitation among employees in Norwegian smelters: a longitudinal study

Aims To investigate the association between airflow limitation and occupational exposure and to compare a fixed limit with an age adjusted limit for airflow limitation. Methods 3924 employees in 24 Norwegian smelters and related workplaces were investigated annually over 5 years (n=16 570) using spirometry and a respiratory questionnaire on smoking habits and job category. Employees working full time on the production line were classified as line operators; subjects who never worked on the production line were regarded as non-exposed. A job exposure matrix (JEM) was available in most smelters. Airflow limitation was expressed as (i) forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC ratio) <0.7 and (ii) FEV1/FVC ratio less than the lower limit of normal (LLN). Longitudinal analyses on the prevalence of airflow limitation were performed using a generalised linear mixed model. Results The prevalence of airflow limitation was stable during follow-up. The OR of airflow limitation during follow-up was 1.24 (95% CI 1.03 to 1.50) in line operators compared with unexposed subjects for FEV1/FVC ratio <0.7 and 1.44 (1.14 to 1.81) for FEV1/FVC ratio <LLN. A dose–response relationship was also found between prevalence of airflow limitation and dust exposure. The annual decline in FEV1 was −77.5 (SD 99.9) ml/year in subjects with FEV1/FVC ratio <0.7 and −83.8 (114.2) ml/year in subjects with FEV1/FVC ratio <LLN. Conclusion Prevalence of airflow limitation was higher in exposed than non-exposed employees. Both the FEV1/FVC ratio <0.7 and FEV1/FVC ratio <LLN identify subjects with accelerated annual decline in FEV1.

A method for establishing tentative occupational exposure limits for inhalable dust

Four-fold classification tables are used on five datasets containing 112 parallel personal measurements of total dust and inhalable dust. The classification are carried out in such a way that the frequency of non-compliance is equal for total dust and inhalable dust. The results can be used as tentative occupational exposure limits (OELs) for inhalable dust, and the results range from 0.7 to 3.4 of OELs for total dust. The results depend on the industry and the content of the dust.

Production of silicon metal and alloys is associated with accelerated decline in lung function : A 5-year prospective study among 3924 employees in norwegian smelters

Objectives: To investigate the association between decline in lung function and production of alloys in the Norwegian smelting industry. Methods: All employees (N = 3924) were examined annually for 5 years (16,570 examinations). The employees were classified into three categories: 1) line operators (employed full time in the production line), 2) nonexposed (no exposure last year), and 3) non-line operators (remaining subjects). The outcome variable was expressed as forced expiratory volume in 1 second per squared height (FEV1/height2). Results: In the subcohorts of the ferrosilicon/silicon metal and silicon carbide industries, the differences between line operators and nonexposed workers were −2.3 (−4.3 to −0.3) (CI = 95%) and −5.6 (−10.4 to −0.7) mL/(m2 × year), respectively. Conclusion: Line operators in the ferrosilicon/silicon metal and silicon carbide industries had a steeper annual decline in FEV1/height2 compared with nonexposed workers.

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.

Incidence of airflow limitation among employees in Norwegian smelters

We have investigated the association between the incidence of airflow limitation and occupational exposure. The employees (n = 3,924) were investigated annually during five years (n = 16,570) using spirometry. Exposure was classified using job category and a job exposure matrix. Airflow limitation was expressed using two indices: (i) as forced expiratory volume in one second/force vital capacity (FEV(1) /FVC) <0.7 and (ii) lower limit of normal (LLN). The incidence of airflow limitation was 21.2/1000 years(-1) and 15.1/1000 years(-1) using the fixed limit (0.7) and the LLN criterion, respectively. We found a dose-response relationship between the incidence of airflow limitation and tobacco consumption and with job-category in non-smokers. The associations between airflow limitation and covariates were independent of how airflow limitation was defined. The incidence of airflow limitation defined as FEV(l) /FVC <0.7 yielded higher incidence rates of airflow limitation than LLN. We found a significant association between the incidence of airflow limitation and occupational exposure in non-smokers.

Sampling and chemical characterization of aerosols in workplace air

Contamination of the air in the workroom as well as the outside atmosphere is discussed. The particle type, composition and size distribution of aerosol contaminants is characteristic of a given type of work atmosphere. Health factors are discussed. Sampling methods and the chemical composition of samples are discussed in relation to analytical methods. In particular AAS, flame and electrothermal methods are considered with respect to analysis of these samples. The importance of reference materials and standards is stated. SAMPLING FOR AEROSOLS IN WORKPLACE AIR The inhalation of aerosols is a problem notonlyfor industrial workers but also forthegeneral population. Fractions of the airborne particulates are deposited in the respiratory tract and may give rise to undesirable effects. Since the complete removal of airborne environmental pollutants is impossible, concentration limits for contaminants have been established for a variety of workplaces (threshold limit values (TLV’s)) in an attempt at preventing adverse health effects. The application of modern physical methods in analytical chemistry makes it possible to identify the origin and source of organic and inorganic particulate air pollutants. Some of the most important factors used in the characterization of airborne particulates are size, shape, optical and electrical properties, structure, heterogeneity and chemical composition. The particle type, chemical composition and size distribution of aerosol contaminants are usually quite characteristic for a given type of work atmosphere and affect the deposition of different chemical species in the lung. Total amounts of contaminating particles and droplets are of interest whenever these may cause adverse effects either at or close to deposition sites in the extrathoracic region (i.e. the head), or systemically after deposition of soluble materials anywhere in the respiratory tract.