Regulatory and Communication Issues in Hazard Assessments


Wednesday, May 25, 2016, 10:00 AM - 12:00 PM


Experimental Measurements of the Interzonal Air Flow Parameter (β) for Two-Zone Concentration Modeling

C. Keil, Wheaton College, Wheaton, IL

Objective: Historic, contemporary, and potential exposures to airborne chemicals can be modeled using a variety of approaches. For scenarios where a worker is close to a source, a two-zone model can be used to describe the higher concentrations near the point of pollutant release. The interzonal airflow rate (β) is important in describing the mass flow between near and far zones.

Methods: β was measured in 74 experiments conducted in 13 indoor airspaces. The airspace ranged in volume from 79 to 1,000 m3. The air change rates ranged from 0.20 to 21 ACH. Tracer vapors were released at known rates and the resulting concentration were measured by 4 photoionization detectors in the near zone around the point of release. A robot arm was used to simulate worker motion in the near field. The tracer mass release rate and the measured vapor concentrations were used to solve mass balance equations for β.

Results: The mean value of β for all air spaces was 5.2 m3/min (95% CI 3.4 - 7.0) and the geometric mean was 3.4 m3/min (95% CI 2.5 - 4.5).

Conclusions: These values will be useful in applying the two-zone model for estimation of workers’ exposures near sources of air pollutants.



Managing Compliance to New N-Methyl Pyrrolidone (NMP) PEL: A Challenge for the IH Professional

A. Torres, Northrop Grumman Corporation, Redondo Beach, CA; N. Mack, Northrop Grumman, Torrance, CA

Situation/Problem: N-Methylpyrrolidone (NMP) is a highly effective solvent cleaner for various materials, making it a widely used chemical in many industries, including aerospace. NMP is currently listed as a California Proposition 65 chemical due to its reproductive/developmental toxicity and exposure may result in both short and long term adverse health effects to workers. In 2014, CalOSHA published a NMP PEL of 1.0 ppm. This new PEL poses challenges for some industries because many different chemicals and products contain NMP. The California Department of Public of Health has developed regulations for material handling and use of NMP, as well as a list of alternative chemicals to substitute NMP. Despite all this, industries have continued to use NMP due to its high performance and effectiveness. Furthermore, any modifications altering the process could cause complications and potential extensive requalification procedures that could lead to additional losses such as time and other resources. In addition to the challenge of enforcement from a safety perspective, is the challenge of shifting the work culture. Due to this recent change in CalOSHA exposure regulations, Industrial Hygienist/ Safety Professionals are tasked to assist in managing industry compliance to the new standard without disrupting daily operations.

Resolution: Industrial Hygienist/Safety Professionals developed strategies to address the challenges associated with complying with the new NMP standard with existing processes. Addressing the task includes effectively identifying NMP usage, assessing exposure potential for each process, determining how to mitigate/minimize exposure to NMP through engineering controls/PPE, and educating affected personnel.

Results: Process activities which utilized NMP, successfully met the new compliance standards through collaborative efforts between Industrial Hygienists/Safety Professionals, employees, management, facilities and vendors.

Lessons learned: To achieve success in meeting the new compliance standards, it is essential that employees, management and facilities are fully engaged in their efforts. Although FedOSHA has not adopted this new standard, industries should take a pro-active approach in identifying NMP in their processes and deploy measures to mitigate exposure risks. This will help minimize potential production interruption if compliance standards become adopted.



Justification for an Occupational Exposure Limit for Shale Gas Mixture

P. Haas, Ever Green Health and Safety Consulting LLC, Palm Beach Gardens, FL

Situation/Problem: There is the potential for significant worker exposures to hydrocarbon vapor from production equipment used to extract shale reserves at well sites. Emissions from storage tanks at well sites have also led to serious exposure risks. Emissions include a bolus or plume of released vapor in the form of pressurized gas and mist when a tank inspection hatch is opened for workers to check volumes of liquid. Reported exposures to massive amounts of the hydrocarbon mixtures in the plume have resulted in lightheadedness, shortness of breath and suffocation (arrhythmia, anoxia and death).

Resolution: Using data contained in environmental, health, marketability and research reports, a case can be made for an occupational exposure limit (OEL) for shale gas hydrocarbon vapors. An OEL-C (ceiling limit) for bolus exposures may be the safest alternative. Anecdotal information suggests the primary compounds are light-end aliphatic compounds including methane, butane, and propane up to hexane (C2-C7). Interim OEL’s for controlling exposures exist on the basis of: industry practice API 18.1, interventions from recent governmental evaluations of reports of fatalities, and oil and gas industry requirements. NIOSH Current Intelligence Bulletin (CIB-66) recommends an OEL Ceiling limit (C-OEL) for compounds with health-based IDLH values which are greater than 10% of the lower explosive limit (10% LEL).

Results: Because of the compositional, mixture and toxicological variations in shale gas mixtures, there are many obstacles to providing a single limit, or even multiple provisional limits for worker health. There are hurdles to overcome in estimating what extent of the total amount of the gas vapor in a bolus exposure is potentially inhaled displacing oxygen and how this exposure causes effects to health. This invites controversy as to what portion of the total dose a worker should receive (5%, 10%... 40% of the LEL) before deciding a safe limit. This discussion does not intend to cover the great deal of toxicological research needed or decision making required to arrive at an OEL. This presentation offers relevant data and makes a case for consensus among the industry and scientific community concerned with limiting health effects to workers from exposures to shale gas mixtures.

Lessons learned: Recent reports of exposures suggest that the practice of tank gauging for shale gas warrants intervention. Government evaluations of the fatalities and allied oil and gas industry partners are considering changes to exposures by recommending an OEL. Obviously, across the far reaching shale plays in the U.S. and worldwide the composition of a production mixture could widely vary; so this estimate needs a great deal of research in order to bear out a common toxicological profile. Recent evidence from U.S. fatalities in the Bakken shale and reports of air samples from other locations bears out a commonality, on the basis of reported concentrations of methane, butane, propane up to n-hexane gas mixtures evolved which may be found in concentrations up to 40% of LEL in the bolus. Calculations of exposure limits for shale gas concentration using a method analysis as described by ACGIH® TLV® Appendix H. Reciprocal Calculation Method for Certain Refined Hydrocarbon Solvent Vapor Mixtures and others such as the British Health and Safety Executive Reciprocal calculation procedure for mixtures of hydrocarbon solvents are discussed as a means beyond using 10% of the LEL as an interim control step of worker safety and health.



Premiering the NIOSH Manual of Analytical Methods, 5th Edition

P. O'Connor, CDC/NIOSH, Cincinnati, OH

Objective: The NIOSH Manual of Analytical Methods (NMAM) is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed. In 2016, the NMAM will begin publishing the 5th Edition.

Methods: The 1st edition of the NMAM was published in 1975. For this 5th edition, there will not be a printed version of the NMAM. This will be a living document: meaning that as the methods and chapters are reviewed and approved they will be posted on the NMAM Website. The results of a survey of NMAM users helped shape the direction of the 5th edition, with new and updated chapters as well as new methods for air sampling, for biomonitoring and for w​​​ipe sampling. A number of the new methods were published in collaboration with our international partners. The webpage has a new look that uses a responsive design format to allow viewing of the NMAM on any electronic device. In addition to access of all the methods for the 5th edition, the “historical” 4th edition will still be available for use.

Results: Methods for assessment of workplace air quality were evaluated by using air samples taken in controlled laboratory atmospheres. These sample results were evaluated using the NIOSH Accuracy Criteria as well as determining the methods’ bias and precision. Examples of some of the new methods are wipe methods for methamphetamines, elements using microwave digestion, and measuring such compounds as acetone or toluene in biological matrices such as urine or blood. A new method that combines a great number of the 4th Edition NMAM volatile organic compound (VOC) methods into one method (with all the evaluation data in one place) should allow industrial hygiene labs to be accredited now for just one method while retaining the ability to analyze many VOCs under their accreditation.

Conclusions: Harmonization of NIOSH methods with related voluntary consensus standards is a strategic goal for the 5th edition of NMAM. This 5th Edition NMAM is responsive to the current needs of the industrial hygiene community and the living nature of the document lends itself to adaption to meet any future needs in occupational exposure assessment.



Assessment and Control of Low Observable Sanding Processes on F-22 Aircraft


Situation/Problem: US Air Force F-22 aircraft use Chromium VI and silver paints as part of the low observable stealth coatings. As part of the maintenance of the aircraft along with maintenance of the stealth coatings, Low Observables (LO) workers hand and pneumatic sand aircraft to remove coatings to allow for reapplication. The 154 Wing LO shop needed to move to a new building due to renovations of their current facility. A new controls scheme needed to be developed in compliance with OSHA substance specific standards and Air Force Instructions (AFI).

Resolution:  The Air Force Bioenvironmental Engineering flight performed 4 sets of personal and area samples to determine the extent of the chromium VI and silver exposures. This data was used to develop a control scheme and housekeeping plan for the control of the chromium VI and silver exposure along with establishing regulated area extent.

Results: Statistical analysis for personal and area samples showed a 95th percentile personal exposure to chromium VI of 0.001 mg/m3 with an exceedance fraction of 0.599%. Analysis of silver data showed a 95th percentile personal exposure of 0.181 mg/m3 with an exceedance fraction of 55.3%. Area samples at the 20’ distance also showed silver samples above the PEL for silver, but levels below the PEL at 40’. A 40’ cordon from hazard point of generation was established for sanding processes. LO workers inside the cordon utilize ventilated sanders and full face respiratory protection. Additionally, a thorough contamination control plan was developed to support LO workers and reduce chromium VI and silver contamination.

Lessons learned: Sometimes the expected worst hazard is not the hazards that drives control actions. Worker practices are a dominant determinant of exposure. Different areas of the aircraft have different stealth coating layups and this will drive level of exposure to workers.



What Do You Mean My Laboratory Report May Have Errors? Successful Methods for Identifying, Mitigating, and Managing Data-Related Errors

S. Funk, R. Strode and A. Duane, Chemistry & Industrial Hygiene, Inc., Wheat Ridge, CO

Situation/Problem: All analytical data are subject to both random and systematic errors. Through deliberate efforts, the IH should try to minimize potential errors associated with data generation. Many IHs consider laboratory data ready for use and interpretation. However, laboratories are not infallible and errors associated with reported results should be anticipated and controlled. Some common issues associated with the laboratory data include rounding errors, transcription errors, and significant figure errors. Additionally, mistakes made by the IH in the field, or in reporting field related information to the laboratory, may also occur before and after sample submission, including transcription and statistical calculation errors. From a health protection and liability perspective, making exposure and risk assessments, or other data-based determination using inaccurate data can be a serious problem for both the exposed individual(s) and the IHs performing the work.

Resolution: As an IH you should be intimately familiar with your data and establish a QA/QC process to ensure data accuracy and completeness. All field generated data provided to the laboratory should be reviewed prior to laboratory receipt or analysis, and all laboratory generated data should be reviewed upon receipt of the laboratory work order notification, and after analysis. An approach was developed and implemented to ensure a thorough QA/QC procedure with tracking capabilities for all samples that are collected by field personnel. In this process, all data are reviewed at multiple levels, utilizing a systematic QA/QC approach. Implementation of these processes has reduced the errors associated with reported data, from sample collection through use of the data in assessing exposures and risks.

Results: Both personnel and laboratory errors associated with sample collection were identified that would have been missed. Reducing these errors is very important as any data errors are magnified during exposure and risk assessments, or other data-based calculations.

Lessons learned: The error associated with data collection and analysis can be significantly reduced with simple standardized QA/QC procedures, and by the IH taking ownership of the data they collect.​