F. Parker, G. Luther, R. Conrad, Environmental Technologies Inc., Magnolia, TX.
This presentation describes the results of a 10-year study on the reliability of using percent concentration of benzene in cargos and the semiquantitative variables of low wind, stable air, and high temperature to predict the maximum and average benzene exposure concentrations to workers in a maritime environment.
In 1991, the U.S. Coast Guard promulgated a regulation governing exposure to benzene vapors on maritime vessels. The regulations required that the workers’ exposures be monitored when the “maximum” exposure concentrations would be expected, which the U.S. Coast Guard defines as the month of August, low wind, stable air, and high temperature. The regulation only excludes vessels “carrying liquid cargoes containing less than 0.5% benzene.”
The relationship between these variables and worker exposure was correlated based on 10 years of data collected during cargo transfer operations on 48 ships and 14 barges in the Gulf of Mexico, Atlantic and Pacific Oceans, and the North and Red Seas. A total of approximately 1300 TWAs and 525 STELs were collected using 3M OVM badges and analyzed by AIHA accredited laboratories using standard methods. Simple correlation calculations [Excel Correl] indicate poor correlations between these variables and worker exposure to benzene. The best correlation found was between percent benzene concentration in the cargo and the maximum TWA [0.54]. Other correlations were substantially less, some were even negative, and there was no relationship between months and exposure concentrations.
B. Fotta, P. Jurovcik, D. Reinke, NIOSH, Pittsburgh, PA.
Observing and recording workplace activities and worker behaviors in real-time (time-activity studies) can be a powerful tool for identifying the determinants of exposure. However, the difficulties inherent in hand recording, editing, and coding observational data can limit both its utility and effectiveness as an aid in exposure assessments. These limitations became particularly evident during a noise exposure assessment of drill rig operators working at surface mines, where rapid changes in drilling operations and rig operator behaviors occurred simultaneously or in quick succession. In response to these limitations, a feasibility study examined an alternative method of collecting observational data using a handheld personal digital assistant (PDA) and an observational software system, originally developed to record animal behaviors. Using this system, a data acquisition file was created by entering nine rig activities and five worker behaviors that were of interest to record. By installing this file onto a PDA, field observations were easily captured by touching a stylus to the appropriate screen display of predefined behaviors or rig activities to turn them on or off. The resultant file of observations and times of occurrence were downloaded into a spreadsheet. Using a standard statistical software package, each of the 14 different behaviors were converted to dichotomous variables with values recorded at one-second intervals denoting whether the behavior was on (value of one) or off (value of zero). By merging the observational variables with personal noise dosimetry readings in time, the resultant combined data file was easily manipulated to generate graphic and statistical analyses to assess the relationship between observational events and variations in noise exposure. In conclusion, the use of PDAs to record workplace behaviors and events in real-time improves the consistency, accuracy, and breadth of observations, and enhances their utility as an aid in identifying the determinants of exposure.
P. Logan, W. Reagen, 3M Company, St. Paul, MN.
Most mathematical exposure models require an estimate of the ventilation rates and contaminant generation to accurately predict contaminant concentrations. Contaminant generation rates are a critical part of mathematical exposure models and are usually harder to obtain than ventilation rates. Retrospective and prospective exposure assessments can rely heavily on mathematical exposure models to predict past and future exposures. Consequently, new more accurate tools for measuring or estimating generation rates are needed to enhance the application of mathematical exposure models for occupational health studies. Recent developments in analytical methods utilizing Fourier transform infrared (FTIR) spectrometry now enable generation rates to be measured for many chemical mixtures and environmental conditions. The NIOSH Manual of Analytical Methods details the sampling and analytical method utilizing FTIR in method 3800. The FTIR technique applied to a test chamber provides simultaneous, real-time measurements of many gaseous target analytes from test materials under atmospherically-controlled conditions. Comprehensive emissions analysis, real-time data, controlled atmosphere, and controlled temperature testing conditions result in the data necessary for the determination of quantifiable materials off-gas emission rates. Graphical data from a full production materials emissions study detailing multichemical concentrations versus time will be presented. Applications and illustrations of the FTIR test method to production materials emissions assessments and the experimental equipment will also be presented.
J. Pfaendtner, Northwestern University, Evanston, IL; P. Logan, 3M Company, St. Paul, MN.
Basic characterization is the process of documenting all of the important information about tasks, chemicals, equipment, workforce, and process conditions to make an exposure judgment. For a hygienist at a manufacturing facility, basic characterization provides the foundation for exposure assessment and monitoring activities. The quality of basic characterization information directly effects the efficiency and accuracy with which exposure assessments are completed. Appropriately-detailed basic characterization work affords the hygienist the opportunity to quickly make qualitative exposure assessments, PPE assignments, and also coordinate monitoring activities. This notwithstanding, completing basic characterization for a large manufacturing facility is often a daunting task. We have developed a number of methods and tools that very much streamline the process of basic characterization for a variety of facilities and technology platforms. Discussion topics include efficiently collecting process information, selection and verification of similar exposure groups, selecting the appropriate level of detail for task descriptions, as well as strategies for naming process equipment.
J. Pfaendtner, Northwestern University, Evanston, IL; P. Logan, 3M Company, St. Paul, MN.
All NIOSH, OSHA, and EPA sampling and analytical methods assume the chemicals of interest are known to some extent. Unfortunately, for many new processes scale ups or upset conditions, chemical speciation is not clearly understood which leaves the industrial hygienist in speculation. For the past decade, tremendous advances in computing technology have given rise to a number of exciting developments in the field of kinetic modeling. Complex reacting systems such as polymer degradation or atmospheric chemistry can contain tens of thousands of chemically reacting species and reactions. Historically, such systems have been modeled only in “bulk” fashion, neglecting many important intermediate reactions. As a result, kinetic models for complex systems typically are valid only for very specific conditions such as temperature or pressure. On the contrary, a mechanistic or reaction-network model actually follows the chemical events of every reacting species. Network generation techniques have been demonstrated to be extremely accurate for a number of systems. Network generation techniques are incredibly powerful modeling tools and may have much to offer the speculating industrial hygienist. In broad terms, we will discuss the basic principles of network generation and applications to the field of industrial hygiene.
K. Wisniewski, S. Monk, U.S. Army CHPPM, Aberdeen Proving Ground, MD.
The Department of Defense (DoD) is a multifaceted conglomerate, with 5.3 million employees, 6000 locations, 30 million acres of real estate, 600,000 buildings and structures, and a worldwide presence in over 146 countries. Not surprisingly, DoD organizations differ in industrial hygiene practices. Developing corporate guidance on exposure assessment prioritization presented a challenge.
Using proven practices from each of the military services, we integrated the Navy Health Effects Ranking, the Army Exposure Effect Ranking, and the Air Force Uncertainty Rating Matrix to create the DoD Exposure Assessment Prioritization (EAP). The EAP will be used in implementation of the DoD Exposure Assessment Module. This model is based on the AIHA Strategy for Assessing and Managing Occupational Exposures, and was a critical functional design component of the Defense Occupational and Environmental Health Readiness System-Industrial Hygiene, the automated occupational data management system for DoD. The EAP will be useful in basic characterization when there is little qualitative assessment of occupational hazards and for exposure assessment when more quantitative data is available. The EAP will ensure consistent and comparable prioritization and also provide valuable information for workplace monitoring plans, focusing scarce industrial hygiene resources on high risk situations.
M. Nunnally, 3M Company, Cordova, IL.
WITHDRAWN
C. Carlton, P. Williams, J. Fisher, L. Naeher, The University of Georgia, Athens, GA; D. MacIntosh, Environmental Health & Engineering Inc., Newton, MA; D. Shea, USDA Forest Service, New Ellenton, SC; G. Achtemeier, USDA Forest Service, Athens, GA.
As part of a respiratory health study, exposure to PM2.5 during prescribed forest burns was studied in Winter 2003 in a cohort of 12 forest fighters over a 5-wk study in a southeastern U.S. forest. Fifty-four individual work shift samples were collected during burn activities and 9 during non-burn activities (controls). Over the 5-wk study, there were 9 days of prescribed burn activity when firefighters were sampled, with an average of 5.4 firefighters monitored per burn. Burn sizes ranged 1 to 2042 acres (avg = 613.1 acres). Workers were studied for an average duration of 7.9 hrs. Samples were collected using an SKC pump at 4.0 L/min with a BGI KTL cyclone and 2.0-micron pore size glass-fiber Teflon-coated filters. The overall average PM2.5 for the 54 burn activity samples was 385.5 ug/m3 (range 21.3–2462 ug/m3 ). Daily PM2.5 24-hr measures were taken during the study period as a measure of background PM2.5 in the area. A daily exposure questionnaire was administered daily post-shift to qualitatively assess worker exposure to smoke. A time activity diary (TAD) was also administered daily post-shift to study worker activities. This study investigates personal PM2.5 and the utility of using a post-shift questionnaire and TAD to predict these exposures. Results of the study show a positive correlation between personal PM2.5 and personal questionnaire assessed measure of smoke exposure (high, medium, low). Personal PM2.5 was also correlated with the size of the prescribed burn. This study is unique because it provides a true snapshot of what one fire worker might expect as an average exposure during 8 burns or 5-weeks of a given prescribed burn season. Data from this suggest that prescribed forest burn-related occupational exposures to PM2.5 are of concern for forest fighters and warrant further exposure and health effects studies.
Posted May 30, 2004