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Results for “Threshold Limit Values”

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Are we closer to developing threshold limit values for allergens in the workplace?

The use of immunoassays has facilitated the measurement of high molecular weight sensitizers, usually protein molecules, in the picogram and nanogram per cubic meter range. This facilitated the evaluation of exposure response relationships for bakery workers, exposed to wheat allergens and fungal alpha-amylase and other groups exposed to other allergens such as laboratory animal workers. The application for the standard setting is still limited and requires rigorous standardization, but can be expected in the near future.

Allergens↗

A description of the standardized measurement procedures and recommended threshold limit values for biological hazards in Germany.

On the basis of EU directives 89/391/EEC (to encourage improvements in the safety and health of workers at work) and 2000/54/EC (on the protection of workers from risks related to exposure to biological agents at work), biological hazards at work have to be assessed and preventive measures have to be introduced in all member states of the EU. In Germany, national legislation (Biological Agents Ordinance - BioStoffV and Technical Rules on Biological Agents, TRBA) and recommendations of workers' compensation boards define standardized methods for the assessment of airborne mold, bacteria, and endotoxins. This article describes policies and practices in Germany for measurement of airborne bioaerosols and for interpretation of measurements relative to the standards. As an example, methods and results of measurements in agriculture are shown. The standardized measurement procedures proved suitable for use in livestock buildings. The results of the exploratory measurements in different livestock buildings confirmed the often high concentrations of airborne biological hazards in agriculture that are reported in the literature.

Agricultural Workers' Diseases↗

Should the threshold limit value for power frequency (60 Hz) magnetic fields be changed? Perceptions among scientists and other risk experts.

Over the past few years several studies have raised questions about childhood cancer and exposure to electric and magnetic fields (EMFs). Reports by the National Academy of Sciences and the National Cancer Institute concluded that there is no clear, convincing evidence that exposure to electric power lines and electric power appliances is a threat to human health, whereas the National Institute of Environmental Health Sciences concluded that there is weak evidence that EMF exposure may be a leukemia hazard. Based on the conflicting agency reports on EMF, what do experts in the field of bioelectromagnetics believe regarding the effectiveness of the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines? Surveys were sent to 163 participants at the 1997 annual Department of Energy Contractors meeting on Electric and Magnetic Fields. Approximately one-half (49%, n = 81) of the participants returned the survey. Utility workers demonstrated greater levels of agreement with the current TLV standard in comparison to government, university, and other private sector workers. Utility workers were less likely to perceive that ACGIH guidelines should be changed to be made more strict. In addition, workers who had worked at their present job for 10 years or more indicated less agreement with the acceptability of ACGIH guidelines to protect workers' health. The scientists and other risk experts in this study illustrate the importance of how type of industry may influence perceptions of TLV effectiveness.

Adult↗

Quantitative level of protection offered to workers by ACGIH threshold limit values occupational exposure limits.

The details of the example or modeling methodologies used herein are not critical to the general point of this article, which advises the estimation of residual risk at the OEL by using some quantitative modeling structure. Specifically, the authors believe that an explicit attempt to gauge the level of residual risk at the OEL based on conceptual stochastic models with transparent and testable assumptions could be seen as an important enhancement to the process. This is especially true in sharing the OEL deliberations and explaining OEL decisions to the stakeholders. Indeed, if this approach is used, it is critically important to understand and continually communicate that this "cloud of uncertainty" represents model estimates in which the true risk would most likely be less than worst case estimates and could possibly be zero. It is also possible but highly unlikely that it could be higher than the worst case upper-bound estimate. The above quantitative estimation scheme represents a possible improvement that could provide a reasoned attempt on the part of the risk assessors to use rational science (i.e., conceptual models with transparent and testable assumptions) to inform all of the OEL users and stakeholders of their meaning.

Air Pollutants, Occupational↗

Perspectives on what we formerly called threshold limit values.

From the point of view of an epidemiologist with experience in community air quality standards, occupational health standards, radiation standards, and water quality standards, reasons are given for discarding the assumption that occupational health protection should be based on threshold concepts. The weakness of worker health protection based on prescription of maximal exposure levels is noted, regardless of whose judgement is used for such levels.

Air Pollutants, Occupational↗

Can a threshold limit value for natural rubber latex airborne allergens be defined?

BACKGROUND: Recent studies have shown that systemic or respiratory occupational responses to latex can be induced by inhalation of latex aeroallergens. OBJECTIVE: Our objectives were to study the relationship between exposure to different latex aeroallergen levels and type I allergic reactions in subjects with occupational contact with latex and to assess a threshold value for latex airborne allergens required for sensitization and symptom elicitation. METHODS: We screened 145 subjects working in 32 hospitals or operating rooms with different latex aeroallergen levels. The quantified latex aeroallergen concentrations in the 32 rooms were compared with latex-related allergic symptoms. RESULTS: Different latex aeroallergen concentrations could be detected in rooms where powdered latex gloves were used and no effective ventilation systems were installed. In environments with latex aeroallergen levels of 0.6 ng/m3 or greater, the reported workplace-related symptoms were significantly increased (p < 0.02). All 22 subjects with latex-specific IgE antibodies worked in rooms contaminated with latex aeroallergens (p < 0.05). CONCLUSIONS: Our results demonstrate that symptoms and presence of latex-specific IgE antibodies in subjects are significantly associated with measurable levels of latex aeroallergens. A latex aeroallergen level of 0.6 ng/m3 is a critical threshold, especially for health care workers who are sensitized to natural rubber latex.

Air Pollutants, Occupational↗