Occupational exposure to magnetic fields and electric shocks and risk of ALS: The Swiss National Cohort

Amyotrophic lateral sclerosis (ALS) has been associated with exposures in so-called 'electrical occupations'. It is unclear if this possible link may be explained by exposure to extremely low-frequency magnetic fields (ELF-MF) or by electrical shocks. We evaluated ALS mortality in 2000-2008 and exposure to ELF-MF and electrical shocks in the Swiss National Cohort, using job exposure matrices for occupations at censuses 1990 and 2000. We compared 2.2 million workers with high or medium vs. low exposure to ELF-MF and electrical shocks using Cox proportional hazard models. Results showed that mortality from ALS was higher in people who had medium or high ELF-MF exposure in both censuses (HR 1.55 (95% CI 1.11-2.15)), but closer to unity for electrical shocks (HR 1.17 (95% CI 0.83-1.65)). When both exposures were included in the same model, the HR for ELF-MF changed little (HR 1.56), but the HR for electric shocks was attenuated to 0.97. In conclusion, there was an association between exposure to ELF-MF and mortality from ALS among workers with a higher likelihood of long-term exposure.

Parental demographic risk factors and occupational exposure to ionizing radiation for achondroplasia, thanatophoric and autosomal deletions in Texas, 1996--2002

Little is known about the etiology of Achondroplasia (AC), Thanatophoric Dwarfism (TD), and autosomal deletions (CD). These syndromes are due to fully penetrate genetic mutations, yet arise de novo, instead of being inherited. We examined the association between parental demographic characteristics and parental occupations with exposure to ionizing radiation and these birth defects. ^ We conducted a cross-sectional study and two case-control studies using a large database that was created by linking records from Texas Birth Defects Registry, Texas birth certificates and Texas fetal death certificates from 1996 to 2002. The first case-control study was matched on paternal age and examined 73 cases of AC and 43 cases of TD. The second case-control study was unmatched and examined 343 cases of autosomal deletion syndromes. ^ We used a job exposure matrix (JEM) to measure exposures to ionizing radiation in the workplace. This gives an estimate of the intensity and probability of exposure to ionizing radiation for each occupation and industry. ^ The prevalence rate of Achondroplasia, Thanatophoric Dwarfism and autosomal deletions was 0.36 per 10,000, 0.21 per 10,000, and 1.68 per 10,000 births respectively in Texas 1996–2002. ^ Older fathers had a strong increase in the risk of having offspring with AC or TD and a modest increase in the risk of CD. Fathers who were Black or Hispanic were less likely to have infants with AC or TD compared to Whites (adjusted POR=0.61; 95% CI 0.30, 1.26 and 0.44; 95% CI 0.27, 0.88, respectively). Black fathers and Hispanic mothers were also less likely to have infants with CD (adjusted POR=0.54; 95% CI 0.22, 1.35 and 0.62; 95% CI 0.39, 0.97). ^ After adjusting for other parental demographic factors, there was no significant relation between fathers exposure to ionizing radiation in the work place and AC or TD (adjusted OR=0.48; 95% CI 0.19, 1.25) and no significant relation between parental exposure to ionizing radiation in the work place and CD (adjusted OR=1.16; 95% CI 0.73, 1.85). ^ This is the first study to find an association between father's age and TD and CD and paternal race and AC or CD. Parental exposure to radiation for therapeutic or diagnostic indications was not measured, thus it can not be excluded as a cause of these birth defects. ^

Cytogenetic assessment of occupational exposure to antineoplastic agents

This study has evaluated the utility of measuring effects of low level occupational exposure of nursing personnel to antineoplastic agents. The effect measured in this study is chromosomal damage in peripheral lymphocytes (chromosomal breakage and micronuclei frequency).^ Using nursing personnel in three exposure classifications (low, moderate and high) and breast cancer patients before and after treatment with antineoplastic agents, a weak but statistically significant association was found between exposure and chromosomal damage. Of special interest was the finding that consistent glove usage was negatively associated with increased chromosomal damage.^ The study also demonstrated a statistically significant association between the two measures of chromosomal damage: chromosomal breakage and micronuclei frequency. This suggests that the micronucleus method is a useful test for studying cytogenetic effects in lymphocytes. ^

Leukemia and occupational exposure to electromagnetic fields: An incident case-control study

The existence of an association between leukemia and electromagnetic fields (EMF) is still controversial. The results of epidemiologic studies of leukemia in occupational groups with exposure to EMF are inconsistent. Weak associations have been seen in a few studies. EMF assessment is lacking in precision. Reported dose-response relationships have been based on qualitative levels of exposure to EMF without regard to duration of employment or EMF intensity on the jobs. Furthermore, potential confounding factors in the associations were not often well controlled. The current study is an analysis of the data collected from an incident case-control study. The primary objective was to test the hypothesis that occupational exposure to EMF is associated with leukemia, including total leukemia (TL), myelogenous leukemia (MYELOG) and acute non-lymphoid leukemia (ANLL). Potential confounding factors: occupational exposure to benzene, age, smoking, alcohol consumption, and previous medical radiation exposures were controlled in multivariate logistic regression models. Dose-response relationships were estimated by cumulative occupational exposure to EMF, taking into account duration of employment and EMF intensity on the jobs. In order to overcome weaknesses of most previous studies, special efforts were made to improve the precision of EMF assessment. Two definitions of EMF were used and result discrepancies using the two definitions were observed. These difference raised a question as to whether the workers at jobs with low EMF exposure should be considered as non-exposed in future studies. In addition, the current study suggested use of lifetime cumulative EMF exposure estimates to determine dose-response relationship. The analyses of the current study suggest an association between ANLL and employment at selected jobs with high EMF exposure. The existence of an association between three types of leukemia and broader categories of occupational EMF exposure, is still undetermined. If an association does exist between occupational EMF exposure and leukemia, the results of the current study suggest that EMF might only be a potential factor in the promotion of leukemia, but not its initiation. ^

An assessment of the relative influence of a vapor recovery system in reducing occupational exposure to volatile organic compounds in high performance liquid chromatography

Occupational exposures to organic solvents, specifically acetonitrile and methanol, have the potential to cause serious long-term health effects. In the laboratory, these solvents are used extensively in protocols involving the use of high performance liquid chromatography (HPLC). Operators of HPLC equipment may be potentially exposed to these organic solvents when local exhaust ventilation is not employed properly or is not available, which can be the case in many settings. The objective of this research was to characterize the various sites of vapor release in the HPLC process and then to determine the relative influence of a novel vapor recovery system on the overall exposure to laboratory personnel. The effectiveness of steps to reduce environmental solvent vapor concentrations was assessed by measuring exposure levels of acetonitrile and methanol before and after installation of the vapor recovery system. With respect to acetonitrile, the concentration was not statistically significant with p=0.938; moreover, exposure after the intervention was actually higher than prior to intervention. With respect to methanol, the concentration was not statistically significant with p=0.278. This indicates that the exposure to methanol after the intervention was not statistically significantly higher or lower than prior to intervention. Thus, installation of the vapor recovery device did not result in statistically significant reduction in exposures in the settings encountered, and acetonitrile actually increased significantly.^

Use of a modified delphi process for establishing occupational exposure limits in support of health surveillance for space travelers

On-orbit exposures can come from numerous factors related to the space environment as evidenced by almost 50 years of environmental samples collected for water analysis, air analysis, radiation analysis, and physiologic parameters. For astronauts and spaceflight participants the occupational exposures can be very different from those experienced by workers performing similar tasks in workplaces on Earth, because the duration of the exposure could be continuous for very long orbital, and eventually interplanetary, missions. The establishment of long-term exposure standards is vital to controlling the quality of the spacecraft environment over long periods. NASA often needs to update and revise its prior exposure standards (Spacecrafts Maximum Allowable Concentrations (SMACs)). Traditional standards-setting processes are often lengthy, so a more rapid method to review and establish standards would be a substantial advancement in this area. This project investigates use of the Delphi method for this purpose. ^ In order to achieve the objectives of this study a modified Delphi methodology was tested in three trials executed by doctoral students and a panel of experts in disciplines related to occupational safety and health. During each test/trial modifications were made to the methodology. Prior to submission of the Delphi Questionnaire to the panel of experts a pilot study/trial was conducted using five doctoral students with the goals of testing and adjusting the Delphi questionnaire to improve comprehension, work out any procedural issues and evaluate the effectiveness of the questionnaire in drawing the desired responses. The remainder of the study consisted of two trials of the Modified Delphi process using 6 chemicals that currently have the potential of causing occupational exposures to NASA astronauts or spaceflight participants. To assist in setting Occupational Exposure Limits (OEL), the expert panel was established consisting of experts from academia, government and industry. Evidence was collected and used to create close-ended questionnaires which were submitted to the Delphi panel of experts for the establishment of OEL values for three chemicals from the list of six originally selected (trial 1). Once the first Delphi trial was completed, adjustments were made to the Delphi questionnaires and the process above was repeated with the remaining 3 chemicals (trial 2). ^ Results indicate that experience in occupational safety and health and with OEL methodologies can have a positive effect in minimizing the time experts take in completing this process. Based on the results of the questionnaires and comparison of the results with the SMAC already established by NASA, we conclude that use of the Delphi methodology is appropriate for use in the decision-making process for the selection of OELs.^

Occupational exposure to chloroprene.

Mode of access: Internet.

Occupational exposure to acetylene.

Mode of access: Internet.

Occupational exposure to styrene.

"September 1983."

Occupational exposure to refined petroleum solvents.

Issued July 1977.

Occupational exposure to carbon monoxide.

Mode of access: Internet.

Occupational exposure to hand-arm vibration.

Mode of access: Internet.

Occupational exposure to hot environments : revised criteria 1986.

Mode of access: Internet.