A risk assessment for exposure to grunerite asbestos (amosite) in an iron ore mine

The potential for health risks to humans exposed to the asbestos minerals continues to be a public health concern. Although the production and use of the commercial amphibole asbestos minerals—grunerite (amosite) and riebeckite (crocidolite)—have been almost completely eliminated from world commerce, special opportunities for potentially significant exposures remain. Commercially viable deposits of grunerite asbestos are very rare, but it can occur as a gangue mineral in a limited part of a mine otherwise thought asbestos-free. This report describes such a situation, in which a very localized seam of grunerite asbestos was identified in an iron ore mine. The geological occurrence of the seam in the ore body is described, as well as the mineralogical character of the grunerite asbestos. The most relevant epidemiological studies of workers exposed to grunerite asbestos are used to gauge the hazards associated with the inhalation of this fibrous mineral. Both analytical transmission electron microscopy and phase-contrast optical microscopy were used to quantify the fibers present in the air during mining in the area with outcroppings of grunerite asbestos. Analytical transmission electron microscopy and continuous-scan x-ray diffraction were used to determine the type of asbestos fiber present. Knowing the level of the miner’s exposures, we carried out a risk assessment by using a model developed for the Environmental Protection Agency.

N2 fixation in marine heterotrophic bacteria: dynamics of environmental and molecular regulation.

Molecular and immunological techniques were used to examine N2 fixation in a ubiquitous heterotrophic marine bacterium, the facultative anaerobic Vibrio natriegens. When batch cultures were shifted from aerobic N-replete to anaerobic N-deplete conditions, transcriptional and post-translational regulation of N2 fixation was observed. Levels of nifHDK mRNA encoding the nitrogenase enzyme were highest at 140 min postshift and undetectable between 6 and 9 h later. Immunologically determined levels of nitrogenase enzyme (Fe protein) were highest between 6 and 15 h postshift, and nitrogenase activity peaked between 6 and 9 h postshift, declining by a factor of 2 after 12-15 h. Unlike their regulation in cyanobacteria, Fe protein and nitrogenase activity were present when nifHDK mRNA was absent in V. natriegens, indicating that nitrogenase is stored and stable under anaerobic conditions. Both nifHDK mRNA and Fe protein disappeared within 40 min after cultures were shifted from N2-fixing conditions (anaerobic, N-deplete) to non- N2-fixing conditions (aerobic, N-enriched) but reappeared when shifted to conditions favoring N2 fixation. Thus, unlike other N2-fixing heterotrophic bacteria, nitrogenase must be resynthesized after aerobic exposure in V. natriegens. Immunological detection based on immunoblot (Western) analysis and immunogold labeling correlated positively with nitrogenase activity; no localization of nitrogenase was observed. Because V. natriegens continues to fix N2 for many hours after anaerobic induction, this species may play an important role in providing "new" nitrogen in marine ecosystems.

Fish Consumption and Prenatal Mercury Exposure

Methyl mercury levels in fish tissues have recently become a health issue. Does this toxin adversely affect humans to the point that fish consumption should be severely limited? Health effects of high levels of mercury exposure to human adults are fairly well known, however the effects of lower levels of exposure on human fetal development are less understood. Recent guidelines issued by the United States Food and Drug Agency and the Environmental Protection Agency recommended that pregnant women should refrain from consuming some types of fish, and limit consumption to certain levels, but results of health studies used to develop recommendations were inconclusive when low levels of in-utero methyl mercury exposure were compared. Other studies demonstrated health benefits of fish consumption to developing fetuses. These health benefits may be an over-riding factor, and my interpretation of various studies concludes that restricted consumption of some fish species may be premature at this time due to a need to balance potential health benefits against mercury toxicity hazard.

Environmental and Occupational Optometry. Lesson 4 (Course 2013-2014)

Tema 4. Actividad voluntaria nº 2.

Welfare state regimes and gender inequalities in the exposure to work-related psychosocial hazards

Background: Gender inequalities in the exposure to work-related psychosocial hazards are well established. However, little is known about how welfare state regimes influence these inequalities. Objectives: To examine the relationship between welfare state regimes and gender inequalities in the exposure to work-related psychosocial hazards in Europe, considering occupational social class. Methods: We used a sample of 27, 465 workers from 28 European countries. Dependent variables were high strain, iso-strain, and effort-reward imbalance, and the independent was gender. We calculated the prevalence and prevalence ratio separately for each welfare state regime and occupational social class, using multivariate logistic regression models. Results: More female than male managers/professionals were exposed to: high strain, iso-strain, and effort–reward imbalance in Scandinavian [adjusted prevalence ratio (aPR) = 2·26; 95% confidence interval (95% CI): 1·87–2·75; 2·12: 1·72–2·61; 1·41: 1·15–1·74; respectively] and Continental regimes (1·43: 1·23–1·54; 1·51: 1·23–1·84; 1·40: 1·17–1·67); and to high strain and iso-strain in Anglo-Saxon (1·92: 1·40–2·63; 1·85: 1·30–2·64; respectively), Southern (1·43: 1·14–1·79; 1·60: 1·18–2·18), and Eastern regimes (1·56: 1·35–1·81; 1·53: 1·28–1·83). Conclusion: Gender inequalities in the exposure to work-related psychosocial hazards were not lower in those welfare state regimes with higher levels of universal social protection policies.

Routine histological technique applied to a biological model for environmental studies

Introduction and aim Earthworms are an important test organisms used in several standard ecotoxicological tests (e.g. ISO, 2008, 2012; OECD, 2004, 1094) and they are also model organisms to test soil structure and permeability, as well as for important soil services as the degradation organic matter. Although histopathological changes have been demonstrated to be good biomarkers to assess the exposure of these animals to different physical and chemical stress agents, studies with clear and high quality images describing normal tissue conditions are scarce in the literature, so the aim of this work was to better characterize this biological model. Material and Methods Eight adult earthworms exposed to an artificial standard soil (OECD, 2004) for 28 days, were extracted and placed in a plastic box to depurate their gut content, fixed in 10% neutral-buffered formalin and processed for routine histopathological diagnosis. Results and discussion Satisfactory histological sections were obtained. Some difficulties were faced related with microtome sectioning, resulting in artefacts, namely lines across sections produced by a nick in the cutting edge of the microtome knife cutting tear, motivated by the presence of sand and other solid particles that persisted in the gut of earthworms. Nevertheless, it was possible to obtain representative figures from different earthworm sections. Conclusion Routine histological technique was effective for obtaining satisfactory histological sections and the knowledge of the histology of earthworms could be very useful for future application in environmental studies, using this biological model.

Support document for proposed rule on friable asbestos-containing materials in school buildings : health effects and magnitude of exposure.

Mode of access: Internet.

Economic/social impact of occupational noise exposure regulations : testimony presented at the OSHA hearings on the Economic Impact of Occupational Noise Exposure, Washington, D.C.

Mode of access: Internet.

Methodology for assessing health risks associated with indirect exposure to combustor emissions : interim final.

Mode of access: Internet.

Exposure factors handbook.

Mode of access: Internet.

Radiofrequency radiation levels and population exposure in urban areas of the Eastern United States /

Issued May 1978.

Human exposure model-II : user's guide.

Mode of access: Internet.

Potential effectiveness of barriers toward reducing highway noise exposure on a national scale /

Issued July 1978.

Teratologic effects of long-term exposure to diesel exhaust emissions (rabbits) /

"Contract no. 68-03-2652."