Neil Zimmerman

Lifetime cumulative exposure as a threat for neurodegeneration: need for prevention strategies on a global scale.

Exposure to neurotoxic agents represents a concern of high priority in modern society. The nervous system can compensate for the toxic effects caused by low doses, but prolonged and lifetime exposure can also lead to delayed neurodegenerative effects for very low levels. The reported frequency of neurodegenerative diseases is constantly increasing, resulting in serious negative impacts on the health of the worldwide population. Future estimates indicate that Parkinsons Disease will increase mostly in industrialized countries during the next few years. Exposure to neurotoxic agents can take place during the various phases of life, beginning from the embryonic stage. The time variable plays an important role in neurotoxicity, both in terms of exposure duration and the period of life when it occurs. Prevention and the standards necessary to achieve it are needed to avoid health effects due to lifetime exposure. Risk assessment is a fundamental requirement for risk management and related preventive policies. Therefore, the relationship between exposure and effects should consider measures of cumulative exposure, to integrate both the historical exposure and the exposure to mixed agents, and the related cumulative effects. Examples and suggestions of different metrics for lifetime and cumulative exposure are illustrated in this paper, which reflects a summary of the key note lecture presented at the 10th International Symposium on Neurobehavioral Methods and Effects in Occupational and Environmental Health of the International Commission on Occupational Health.

A new non-destructive method for chemical analysis of particulate matter filters: the case of manganese air pollution in Vallecamonica (Italy).

Total Reflection X-ray Fluorescence (TXRF) is a well-established technique for chemical analysis, but it is mainly employed for quality control in the electronics semiconductor industry. The capability to analyze liquid and uniformly thin solid samples makes this technique suitable for other applications, and especially in the very critical field of environmental analysis. Comparison with standard methods like inductively coupled plasma (ICP) and atomic absorption spectroscopy (AAS) shows that TXRF is a practical, accurate, and reliable technique in occupational settings. Due to the greater sensitivity necessary in trace heavy metal detection, TXRF is also suitable for environmental chemical analysis. In this paper we show that based on appropriate standards, TXRF can be considered for non-destructive routine quantitative analysis of environmental matrices such as air filters. This work has been developed in the frame of the EU-FP6 PHIME (Public Health Impact of long-term, low-level Mixed element Exposure in susceptible population strata) Integrated Project (www.phime.org). The aim of this work was to investigate Mn air pollution in the area of Vallecamonica (Italy).

Airborne particulate matter (PM) filter analysis and modeling by total reflection X-ray fluorescence (TXRF) and X-ray standing wave (XSW)

This work is presented as an improvement of a recently introduced method for airborne particulate matter (PM) filter analysis [1]. X-ray standing wave (XSW) and total reflection X-ray fluorescence (TXRF) were performed with a new dedicated laboratory instrumentation. The main advantage of performing both XSW and TXRF, is the possibility to distinguish the nature of the sample: if it is a small droplet dry residue, a thin film like or a bulk sample. Another advantage is related to the possibility to select the angle of total reflection to make TXRF measurements. Finally, the possibility to switch the X-ray source allows to measure with more accuracy lighter and heavier elements (with a change in X-ray anode, for example from Mo to Cu). The aim of the present study is to lay the theoretical foundation of the new proposed method for airborne PM filters quantitative analysis improving the accuracy and efficiency of quantification by means of an external standard. The theoretical model presented and discussed demonstrated that airborne PM filters can be considered as thin layers. A set of reference samples is prepared in laboratory and used to obtain a calibration curve. Our results demonstrate that the proposed method for quantitative analysis of air PM filters is affordable and reliable without the necessity to digest filters to obtain quantitative chemical analysis, and that the use of XSW improve the accuracy of TXRF analysis.

Effects of respirators on performance of physical, psychomotor and cognitive tasks.

Possible work decrements caused by respirator usage were examined. A battery of physical, psychomotor and cognitive tasks was used to investigate the effects of respirator wear on 12 subjects. A repeated measures experimental design was used to study the effects of three types of respirators: a disposable dust mask; an air purifying half-mask; and a full-face airline mask. Performance while wearing a mask was compared to the control condition without a respirator. The results from the physical work task of riding a bicycle ergometer indicated approximately a 10% increase in oxygen consumption when subjects wore half and full-face masks in comparison to when they performed the tasks without a mask. The results indicate that wearing the respirators did not have a significant effect on the performance of cognitive tasks but did affect significantly the performance of psychomotor tasks such as steadiness of work performance and movements requiring accurate control for positioning of objects.

Ergonomics. The effect of occupational exposure to environmental tobacco smoke on the heart rate variability of bar and restaurant workers.

Changes in heart rate variability (HRV) have been linked with cardiac disease and death. Exposure to particulate matter from various sources such as tobacco smoke has been shown to cause alterations in HRV. This study investigated the effects of occupational exposure to environmental tobacco smoke (ETS) on HRV. Air monitoring was conducted in three bars in which smoking was permitted and one bar where smoking was not permitted. Pre- and post-work shift heart rate monitoring was conducted on volunteer staff from the establishments. Heart rate variability parameters, including SDNN and RMSSD, were calculated, and the differences between pre- and post-shift values were plotted and analyzed with respect to ETS exposure. Post-shift minus pre-shift values of SDNN and RMSSD significantly decreased with exposure to ETS (p < 0.05). Occupational exposure to ETS may decrease heart rate variability.Changes in heart rate variability (HRV) have been linked with cardiac disease and death. Exposure to particulate matter from various sources such as tobacco smoke has been shown to cause alterations in HRV. This study investigated the effects of occupational exposure to environmental tobacco smoke (ETS) on HRV. Air monitoring was conducted in three bars in which smoking was permitted and one bar where smoking was not permitted. Pre- and post-work shift heart rate monitoring was conducted on volunteer staff from the establishments. Heart rate variability parameters, including SDNN and RMSSD, were calculated, and the differences between pre- and post-shift values were plotted and analyzed with respect to ETS exposure. Post-shift minus pre-shift values of SDNN and RMSSD significantly decreased with exposure to ETS (p < 0.05). Occupational exposure to ETS may decrease heart rate variability.

Manganese concentrations in soil and settled dust in an area with historic ferroalloy production

Ferroalloy production can release a number of metals into the environment, of which manganese (Mn) is of major concern. Other elements include lead, iron, zinc, copper, chromium, and cadmium. Mn exposure derived from settled dust and suspended aerosols can cause a variety of adverse neurological effects to chronically exposed individuals. To better estimate the current levels of exposure, this study quantified the metal levels in dust collected inside homes (n=85), outside homes (n=81), in attics (n=6), and in surface soil (n=252) in an area with historic ferroalloy production. Metals contained in indoor and outdoor dust samples were quantified using inductively coupled plasma optical emission spectroscopy, whereas attic and soil measurements were made with a X-ray fluorescence instrument. Mean Mn concentrations in soil (4600 μg/g) and indoor dust (870 μg/g) collected within 0.5 km of a plant exceeded levels previously found in suburban and urban areas, but did decrease outside 1.0 km to the upper end of background concentrations. Mn concentrations in attic dust were ~120 times larger than other indoor dust levels, consistent with historical emissions that yielded high airborne concentrations in the region. Considering the potential health effects that are associated with chronic Mn inhalation and ingestion exposure, remediation of soil near the plants and frequent, on-going hygiene indoors may decrease residential exposure and the likelihood of adverse health effects.

Health Effects Associated With Organic Dust Exposure During the Handling of Municipal Solid Waste

Municipal solid waste is a collection of discarded liquid and solid materials that serves as a breeding ground for bacteria and fungi. Individuals involved in the collection, transport, transfer and management of this waste may be exposed to elevated concentrations of biological aerosols. Based on the nature of the work environment and the knowledge of bioaerosol related health effects in other occupations, the handling of municipal solid waste can be expected to result in adverse health outcomes. Only limited research has been performed to date evaluating the relationship between organic dust exposure and adverse health effects in these workers. The majority of this work has been conducted in Europe, with little performed in the United States. Although not extensive, the existing body of research suggests that there is an association between the performance of job tasks involving the handling of municipal solid waste and various respiratory, dermatologic and gastrointestinal health effects. While increased incidences of specific adverse health outcomes have been documented in this group of workers, the limited nature of exposure assessment in this body of research does not allow for strong evidence based conclusions to be drawn regarding exposure levels and associated health effects. Based on this review it is concluded that the detailed characterisation of organic dust exposure experienced by municipal solid waste workers is necessary in order to both improve understanding of resultant health effects and develop strategies to improve occupational health.

Evaluation of Cut-Off Saw Exposure Control Methods for Respirable Dust and Crystalline Silica in Roadway Construction

Dust reduction equipment adapted for single-person operation was evaluated for gas-powered, commercially available cut-off saws during concrete curb cutting. Cutting was performed without dust control and with two individual exposure control methods: wet suppression and local exhaust ventilation (LEV). The wet suppression system comprised a two-nozzle spray system and a 13.3-L hand-pressurized water supply system with an optimum mean flow rate of 0.83 L/min for 16 min of cutting. The LEV system consisted of a spring-loaded guard, an 18.9-L collection bag, and a centrifugal fan with an estimated exhaust rate of 91 ft3/min. Task-based, personal filter samples were obtained for four saw operators during cutting durations of 4 to 16 min on five job sites. Seventeen filter samples were collected without dust control, 14 with wet suppression, and 12 with LEV, yielding a geometric mean respirable dust concentration of 16.4 mg/m3, 3.60 mg/m3, and 4.40 mg/m3, respectively. A dust reduction of 78.0% for wet suppression and 73.2% for LEV was observed vs. no dust control. A statistically significant difference (p < 0.001) was also revealed for wet suppression and LEV when compared with no dust control; however, a significant difference (p = 0.09) was not observed between wet suppression and LEV. Despite these significant dust reductions, workers are still projected to exceed the ACGIH 8-hr time-weighted average threshold limit value for quartz (0.025 mg/m3) in less than 1 hr of cutting for both dust control methods. Further research is still needed to improve dust reduction and portability of both control methods, but the current LEV system offers important advantages, including a drier, less slippery work area and year-round functionality in cold weather.

The Critical Orifice Revisited: A Novel Low Pressure Drop Critical Orifice

The ability to maintain a constant air flow rate under varying load conditions is of basic importance in air sampling. Critical orifice flow devices are often used to accomplish this. A major disadvantage of most critical orifice designs is that a pressure drop in excess of 350 mm Hg (14 in. Hg) is required to ensure stable flow. It is possible, however, to design a flow restricting device which will function as a critical orifice at pressure drops significantly less than those required for conventional designs. Presented here is an inexpensive and convenient method for controlling flow in the range of 20-90 L/min. Pressure drop versus flow rate data demonstrate that a vacuum of 150 mm Hg (6 in. Hg) or less is required to reach critical flow conditions using this design. Thus the convenience of unattended constant flow rate control with a substantial reduction in vacuum pump capacity and cost is achieved.

Evaluation of Culturable Particle Load on HVAC Filters Before and After Remediation: A Pilot Study

This pilot research was performed to evaluate a quantitative method for culturing particles on HVAC filters. The reasons were to compare relative concentrations of culturable fungi found in two separate rooms of a six-floor building and to re-evaluate culturable fungi in the same building after remediation efforts. The evaluated quantification method involved shaking samples of filter materials in sterile saline followed by plating out. The pilot study consisted of two phases. Firstly, a case study comparison of two HVAC filters from a building with a history of indoor air quality concerns in the space served by one of the filters. The second, following remediation efforts in the same building. This involved the quantification of culturable fungal particles on each of ten filters serving ten separate areas of the building. Statistical analysis of the phase I results indicated a significantly greater number of viable particles on the complaint filter than on the non-complaint filter following culture and quantification on either malt extract agar (p=0.02) or potato dextrose agar (p=0.03). Phase II results suggested a factor of four decrease in culturable fungal load following remediation. This limited study was performed for preliminary assessment of the use of a filter quantification method to estimate relative airborne fungal load. The results suggest that more work is merited but limitations in the scope of the research and the statistical power of the analysis mean further conclusions regarding method efficacy cannot be drawn.