Mortality of mental disorders in relation to potential pesticide exposure

Some studies have suggested a role of pesticide exposure in the development of neurobehavioral disorders. This case-control study examined the association between mortality from mental disorders and occupational exposure to pesticides. The study population consisted of 7756 deaths and 330,452 eligible controls identified from US death certificate files for the years 1988 through 1992. Exposure assignment was based on job title reported on the death certificates. Employment in jobs potentially involving pesticide exposure was weakly associated with the risk of death from mental disorders (odds ratio [OR] = 1.46; 95% confidence interval (95% CI) = 1.33-1.60). This association was stronger among women (OR = 2.65; 95% CI = 1.89-3.71), in particular for deaths from neurotic disorders (OR = 4.32; 95% CI = 2.44-7.64). These results must be interpreted with caution, however, because the impact of social and work-related factors other than pesticide exposure is not known.     

Decrease in selenium status in relation to coal dust exposure

Selenium (Se) plasma levels were studied 222 coal miners to assess whether selenium is decreased in relation to coal dust exposure, taking age, alcohol, and tobacco consumption into account. Selenium levels decreased significantly with age and current tobacco consumption, among miners aged 34–50. Long-term and current exposure to coal dust were studied. The lowest Se values were observed for those with both long-term and current exposure (60.2 ng/ml), the highest for those never or slightly exposed (64.1 ng/ml); those with long-term exposure not currently exposed fell in an intermediate position (61.3 ng/ml). No relation was observed with alcohol consumption. The association of coal dust with low selenium remained significant after adjustment for age and smoking. © 1996 Wiley-Liss, Inc.     

The relation between subjective dust exposure estimates and quantitative dust exposure measurements in California agriculture

Measuring exposure levels for epidemiologic research is time consuming and expensive and therefore subjective exposure estimates are sometimes used instead. In this study we related the subjective dust exposure estimates of workers in California agriculture to personal dust exposure measurements. One hundred and twenty-four observations were available for comparison of subjective dust estimates and inhalable dust measurements and 129 observations for comparison of subjective dust estimates and respirable dust measurements. Individual subjective dust estimates showed weak to moderate correlations with measured dust concentrations for both the inhalable (R_s = 0.67) and respirable dust fraction (R_s = 0.36). The within-worker reliability coefficients were low (0.2 and 0.1, respectively). Grouped subjective dust estimates performed better and showed a consistent increase with average measured dust levels, in particular for the inhalable dust fraction (R² = 0.81). Age, the number of years working in agriculture, education level, the presence of any respiratory symptoms, and the language of the questionnaire did not have a significant independent effect on the relationship between measured dust levels and subjective dust estimates. California agricultural workers appear to be reasonably good at estimating inhalable dust levels, in particular if an average of many different workers is taken, but they are unable to provide good estimates of respirable dust levels. Measuring dust levels remains the preferred option. Am. J. Ind. Med. 32:355–363, 1997. © 1997 Wiley-Liss, Inc.     

A comprehensive assessment of exposures to respirable dust and silica in the taconite mining industry

This study assessed the present-day levels (year 2010–2011) of exposure to respirable dust (RD) and respirable silica (RS) in taconite mines and evaluated how the mining process influences exposure concentrations. Personal samples (n = 679) were collected to assess exposure levels of workers to RD and RS at six mines in the Mesabi Iron Range of Minnesota. The RD and RS concentrations were measured using the National Institute for Occupational Safety and Health (NIOSH) 0600 and NIOSH 7500, respectively. Between-mine, between-SEG (similar exposure groups), within-SEG, and within-worker components of variability for RD and RS exposures were estimated using a two- or three-way nested random-effects ANOVA model. The majority of RD concentrations across all mines were below the Mine Safety and Health Administration (MSHA) Permissible Exposure Limit (PEL). The highest concentrations of RD were often observed in either the Pelletizing or Crushing departments, which are inherently dusty operations. With a few exceptions, the concentrations of RS in the crushing and concentrating processes were higher than those in the other mining processes, as well as higher than the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for RS. The magnetic separation and flotation processes in the concentrating department reduced the levels of RS significantly, and lowered the percentage of quartz in RD in the pelletizing department. There was little variability among the six mines or between the two mineralogically distinct zones for either RD or RS exposures. The between-SEG variability for RS did not differ substantially across most of the mines and was a major component of exposure variance. The within-SEG (or between-worker) variance component was typically the smallest because in many instances one worker from a SEG within a mine was monitored multiple times. Some of these findings were affected by the degree of censoring in each SEG and mine, characteristics of the taconite rock, seasonal effects during sampling, or the tasks assigned to each job in that mine.     

Mortality study of employees with potential exposure to epichlorohydrin: a 10 year update.

OBJECTIVES: A 10 year extension of follow up (up to 1993) of 863 employees who had potential exposure to epichlorohydrin at two chemical plants between May 1948 and December 1965 was conducted to further evaluate the previously reported potential association between exposure to epichlorohydrin and heart disease. METHODS: The mortality observed was compared with that expected from the death rates from the local male population where these chemical plants are located. Workers were assigned to one of five exposure categories based on their job with the highest level of potential exposure. Vital status was ascertained to the end of 1993. RESULTS: Among diseases of particular interest, there were no excess deaths from heart disease (standardised mortality ratio (SMR) 63.3), lung cancer (SMR 63.8), or non-malignant respiratory disease (SMR 37.7) for employees with 20 or more years after first exposure. Based on the level of potential exposure to epichlorohydrin, mortality for heart disease was slightly higher (SMR 75.7, 95% confidence interval (95% CI) 51.8-106.7) in the moderate to heavy exposure group than in the none to light exposure group (SMR 59.5, 95% CI 37.7-89.3); this difference is well within the range of random variation. The SMR for heart disease was 90.4 among employees who had both probable exposure to allyl chloride and moderate to heavy exposure to epichlorohydrin, although it was 88.1 among employees who had moderate to heavy potential exposure to epichlorohydrin but no exposure to allyl chloride. CONCLUSIONS: This study does not support an association between exposure to epichlorohydrin and heart disease or lung cancer. There were no additional deaths from leukaemia in this update; the raised SMR for leukaemia noted in the previous study has substantially decreased from 500.0 to 161.3 (95% CI 33.2-471.0) and is not significant. The overall mortality and cancer mortality of employees potentially exposed to epichlorohydrin continued to be lower than that of the local population.     

Mortality rates in the Federal Republic of Germany following previous occupational exposure to asbestos dust

Summary In 1972, a procedure was introduced by the Industrial Injuries Insurance Institutes (Berufsgenossenschaften) of the Federal Republic of Germany, which is to be used by the special occupational health service for employees exposed to asbestos dust. Since 1 January 1972, occupational health examinations are performed when exposure to asbestos dust has been of at least 3 years' duration.On 1 January 1977, a prospective cohort study was started with employees formerly exposed to asbestos dust whilst working for companies manufacturing or using asbestos. Data on these persons are collected in the Central Register of Employees Exposed to Asbestos Dust of the Industrial Injuries Insurance Institutes. A total of 3,070 male and female employees in whom asbestos exposure terminated after 1 January 1972 formed subcohort I of the study. For comparison, 665 persons whose exposure terminated before 1 January 1972 served as subcohort II. In addition to several other inclusion criteria, each individual's permission was required before personal data could be evaluated.Of the subjects in the two subcohorts, 185 and 71, respectively, had died by 31 December 1982. Tumours were more frequently than this cause of death is expected in the general population. In addition to a high incidence of mesothelioma, the standard mortality rate was especially increased for lung cancer.The proportional mortality rates of about 40% for tumours of all sites (with about 17% lung cancer and 8% mesothelioma) especially in subcohort II, seemed to be comparable to the international figures for epidemiological mortality.Supported by the Central Office of the Industrial Injuries Insurance Institutes, Bonn, Contract no.638.31:376.3-4104.Presented as a Short Communication at the XXI International Congress on Occupational Health, Dublin, September 9–14, 1984.     

Lung function decrease in relation to pneumoconiosis and exposure to quartz-containing dust in construction workers

BACKGROUND: Prevalence of exposure related respiratory symptoms and decreases in lung function are unknown among quartz dust exposed construction workers. METHODS: In a cross-sectional study (n = 1335), the occurrence of respiratory symptoms, was recorded and spirometric lung function was measured. Results were associated with exposure data and presence of radiographic abnormalities and compared with a reference population. RESULTS: Pneumoconiosis (profusion category 1/1 or greater) was associated with increased risks of FEV(1) and FVC values in the lowest 5% group, and with group-based decreases of 270 ml/s and 180 ml, respectively. Average lung function of construction workers was somewhat lower compared to a Dutch reference population. Lung function was not associated with exposure, except for a reduction in FVC of 5 ml per year for those with higher exposure. CONCLUSIONS: In quartz dust exposed construction workers obstructive and restrictive lung function loss was detected.     

Development of a model to aid in reconstruction of historical silica dust exposures in the taconite industry

The ability to reconstruct employee exposure histories would be a valuable research tool for the evaluation of occupation as a factor in disease. In many cases, however, historical environmental data are available but have not been used to compute past exposures because of differences in sampling methods. This paper describes a quantitative model to convert historical environmental data (from taconite mine and mill operations) into a form consistent with current sampling methods and results and, therefore, will enable past exposure histories to be used. (Past exposure histories are to be determined in an epidemiological study.) In this study, parallel sampling results from the environmental data base were used to obtain a coefficient for the conversion of impinger-particle counts (old sampling method) to filter-respirable mass sampling results (new sampling method). Parameters in the model were estimated using multiple regression techniques. Results show that a consistent ratio exists between impinger-particle counts and filter-respirable mass concentrations for samples collected at the same locations.     

Cross-shift changes in FEV1 in relation to wood dust exposure: the implications of different exposure assessment methods

Background: Exposure-response analyses in occupational studies rely on the ability to distinguish workers with regard to exposures of interest.

Aims: To evaluate different estimates of current average exposure in an exposure-response analysis on dust exposure and cross-shift decline in FEV₁ among woodworkers.

Methods: Personal dust samples (n = 2181) as well as data on lung function parameters were available for 1560 woodworkers from 54 furniture industries. The exposure to wood dust for each worker was calculated in eight different ways using individual measurements, group based exposure estimates, a weighted estimate of individual and group based exposure estimates, and predicted values from mixed models. Exposure-response relations on cross-shift changes in FEV₁ and exposure estimates were explored.

Results: A positive exposure-response relation between average dust exposure and cross-shift FEV₁ was shown for non-smokers only and appeared to be most pronounced among pine workers. In general, the highest slope and standard error (SE) was revealed for grouping by a combination of task and factory size, the lowest slope and SE was revealed for estimates based on individual measurements, with the weighted estimate and the predicted values in between. Grouping by quintiles of average exposure for task and factory combinations revealed low slopes and high SE, despite a high contrast.

Conclusion: For non-smokers, average dust exposure and cross-shift FEV₁ were associated in an exposure dependent manner, especially among pine workers. This study confirms the consequences of using different exposure assessment strategies studying exposure-response relations. It is possible to optimise exposure assessment combining information from individual and group based exposure estimates, for instance by applying predicted values from mixed effects models.

     

Bakers' exposure to flour dust

We aimed to characterize bakers' personal exposure to airborne flour dust with respect to the health-related aerosol fractions inhalable, extrathoracic, and thoracic dust, and to examine possible production-related determinants of dust exposure.

Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009–2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients.

Bakers' overall geometric mean personal exposure to inhalable, extrathoracic, and thoracic dust were 2.6 mg/m³ (95% CI: 2.0, 3.2), 2.2 mg/m³ (95% CI: 1.9, 2.7), and 0.33 mg/m³ (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m³. The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust exposure. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p < 0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01).

Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust—likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis—represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.     

Inflammation mediators in employees in chronic exposure to neurotoxicants

Objectives

The aim of this work is to perform comparative estimation of cytokines levels in chlorinated hydrocarbons and metallic mercury exposure in employees in the dynamics of neurologic disorders formation.

Material and Methods

The contents of cytokines IL-1β, IL-2, IL-4, IL-6, TNF-α, INF-Γ were determined in blood sera using the method of hardphasic immunoferment analysis. The significance of different average values was assessed using the parametric and non-parametric criteria — Student (in normal distribution) and Mann-Whitney tests taking into account the Bonferonni correction (non-difference from normal distribution).

Results

It was shown that, a number of inflammation mediators with the dominance, depending on the expositional toxicant and expression of neurological deficiency, take part in the neurointoxication development. Healthy employees show pro-inflammatory responses with different expression degree, which dominate in the immune regulation processes regardless of the expositional factors (metallic mercury vapors and chlorinated hydrocarbons).

Conclusions

The production intensity and interconnection between the pro- and anti-inflammatory cytokines may change in the occupational injuries of the nervous system development process. The decrease in the serum concentrations of cytokines along with the increase of clinical manifestation severity may prove dysregulation of the immune system, which promotes maintaining of pathological process and progradient process of neurointoxication. The most obvious is the imbalance of cytokines in the employees exposed to metallic mercury (in all the examined groups) that increases neurointoxication in the distant period.     

Pleural abnormalities and exposure to elongate mineral particles in Minnesota iron ore (taconite) workers

Background

Iron ore (taconite) mining and processing are an important industry in northern Minnesota and western Michigan. Concerns around exposures have centered largely on exposure to non‐asbestiform amphibole elongate mineral particles (EMPs) found in the eastern portion of the Minnesota iron range.

Methods

A cross sectional survey was undertaken of current and former taconite workers and spouses along with a detailed exposure assessment. Participants provided an occupational history and had a chest radiograph performed.

Results

A total of 1188 workers participated. Potential exposures to non‐amphibole EMPs were evident across multiple jobs in all active mines. Pleural abnormalities were found in 16.8% of workers. There was an association of pleural abnormalities with cumulative EMP exposure that was not specific to the eastern portion of the range.

Conclusion

There was evidence of a mild to moderate increase in pleural abnormalities in this population of miners, associated with geographically non‐specific cumulative EMP exposure.

     

Mortality of employees in plants manufacturing 4,4'-bipyridyl

A historical-prospective cohort study was conducted of 729 male employees of plants manufacturing 4,4'-bipyridyl. The cohort was studied because employment in some of the plants had been linked to malignant and nonmalignant skin lesions attributed to exposure to tarry by-products. The overall mortality experience of the cohort did not show any statistically significant findings. More-detailed analysis of subdivision of the cohort gave results that justified further inquiry into lung cancer incidence. A nested case-referent study did not indicate that any occupational factor other than employment in a bipyridyl plant was related to the incidence of lung cancer. The epidemiologic, toxicologic, and industrial hygiene information was assessed, and it was concluded that there was no evidence of a plausible occupational hazard of lung cancer to the bipyridyl workers, but that a follow-up of the cohort after an interval of five years should be undertaken.     

Mortality in employees of a Scottish paper mill

To assess possible health risks associated with the manufacture of paper, we carried out a retrospective analysis of mortality among 4,242 men and women employed at a Scottish paper mill between 1955 and 1992. During follow-up to 1994, 959 subjects had died giving an SMR of 0.85 (95% CI 0.80–0.90) in comparison with the national population. Mortality from all cancer (SMR 0.77, 95% CI 0.68–0.88) and particularly from lung cancer (SMR 0.64, 95% CI 0.50–0.81) was lower than expected. An excess of lymphatic and hematopoietic cancer (11 deaths, SMR 2.17) was observed in the making department. These findings do not support an occupational hazard of lung cancer as suggested by several earlier studies. The excess of lymphatic and hematopoietic cancer in the making department was unexpected, and may be a chance occurrence. Am. J. Ind. Med. 32:535–539, 1997. © 1997 Wiley-Liss, Inc.