Intriguing Unknown and Known IH Hazards


Thursday, May 26, 2016, 1:00 PM - 3:20 PM


Cold Storage of Fumigated Fruit: Worker Illnesses Uncover an Unforeseen Route of Pesticide Poisoning

H. Fong and P. Tehrani, California Department of Pesticide Regulation, Sacramento, CA

Situation/Problem: In 2010, the California Department of Pesticide Regulation’s (DPR) noted two workers at a cold storage facility in Long Beach had been diagnosed with methyl bromide poisoning. The Worker Health and Safety Branch of DPR investigated the situation, since methyl bromide (MBr), a fumigant, was not normally associated with cold storage facilities. These facilities stored Chilean grapes. Fumigation is required by USDA for imported grapes. Six large cold storage facilities (CSF), that were known to receive fumigated grapes, were investigated using colorimetric tubes. All showed unacceptably high levels (as high as 24 ppm, California PEL = 1 ppm) in the cold storage chillers. As more CSFs were discovered to be accepting fumigated fruit, the monitoring program expanded and in all cases MBr was detected.

Resolution: Two CSFs were selected for intensive monitoring using charcoal tube sampling. One was tested during the first three hours after receiving fruit, the other three days after receiving. Additionally, different mitigation strategies were employed, including extended dockside aeration, in transit venting, predelivery aeration, facility ventilation, filtration, and real-time MBr monitoring.

Results: Overall sampling results indicated that without active control measures, unacceptable levels occur in the chillers, but drop off after 72 hours. Sampling also found that MBr had infiltrated into rooms within the building envelope distant from the chillers holding the fumigated fruit. Some mitigation measures were of little use (extended aeration), while others reduce build-up of MBr in cold storage rooms.

Lessons learned: A state mandated program, designed to mitigate the off-gassing hazard, has been developed in cooperation with the CSFs. Key elements include ventilation, worker education, real-time monitoring of MBR and worker exposure time management. Only CSFs that have this program are allowed to receive and store freshly fumigated grapes. And although the greatest bulk imported fruit required to be fumigated is grapes, other fruits, including kiwis and blueberries, are also fumigated and have been folded into this program.



Protecting Workers Who Manufacture the Insensitive Munitions that Protect the Warfighter

L. Kneten, Army Public Health Center, Bel Air, MD

Situation/Problem: The safety and health of workers in manufacturing the new insensitive munitions IMX is of concern. Three of the four main ingredients of IMX, 2,4-dinitroanisol (DNAN), 3-Nitro-1,2,4-triazol-50one (NTO) and nitroguanidine (NQ) do not have established occupational exposure levels (OELs). Without OELs and exposure assessment methodology, it is unclear whether the workers in IMX Army Ammunition Plants are properly protected.

Resolution: 1. Establish OELs for IMX. The Army Public Health Center (Provisional) conducted toxicology studies and submitted results to the Toxicology Excellence for Risk Assessment (TERA) Occupational Alliance for Risk Science (OARS) to publish Workplace Environmental Exposure Levels (WEELs) for DNAN, NTO and NQ. 2. Establish Sampling and Analytical Methodology. The analytical laboratory at the Army Public Health Center (Provisional) developed procedures for sampling and analysis of DNAN, NTO, and NQ. 3. Conduct Worker Exposure Assessments at IMX Army Ammunition Plants. Comprehensive Industrial Hygiene assessments were conducted at several IMX Army Ammunition Plants. Over 240 personal samples and 620 wipe samples were collected. Personal exposures were measured for each of the explosive compound constituents. Results were compared to recently published OARS WEELs. Controls (engineering and personal protective equipment) at plants were assessed and work practices were observed to identify opportunities to control or eliminate exposures.

Results: Personal air monitoring results and observations from work practices indicate the potential exists for workers to be exposed above the OARS WEELs for three out of the four chemical constituents of the new insensitive munitions explosives. Exposure to NQ was not significant. Poor work practices and improper use of personal protective equipment often contribute to exposure. Production area work surfaces contained high levels of the chemical compounds and validates the need to wear gloves to reduce skin contact.

Lessons learned: Environmental conditions and requirements for intrinsic safety make implementing controls difficult. All equipment must be grounded or classified as intrinsically safe for Class 1, Division 1, Group D. Due to the concentrations of chemicals present workers are wearing flame retardant coveralls and respirators. In addition, the atmosphere temperature must be maintained to at least 85 degrees Fahrenheit in order for the mixture to maintain necessary temperature, which adds to the workers’ heat stress burden.. Until engineering controls can be retrofitted into the operation to reduce and/or control exposures, interventions such as improved personal hygiene, reduced exposure duration, improved housekeeping and work practices, and use of respiratory protection can be used to protect the workers during production operations.



Hazard Assessment of High-Nitrogen Explosive Compounds: A Novel in Vitro Multi-Cellular Approach

T. Maurais, C. Gellasch, and M. Bruggermeyer, DoD, Uniformed Services University of Health Sciences, Bethesda, MD; K. Donohue, N. Garcia-Reyero, E. Perkins, and K. Gust, USACE Engineer Research and Development Center, Vicksburg, MS

Objective: The energetic properties of high-nitrogen (high-N) content materials have increased the interest towards the development of high-N compounds for use in insensitive munitions. However, the use of such compounds is known to lead to an increase risk of adverse health effects towards munition factory workers and the general population. While chemical hazard assessment with live animals has many advantages, the high cost of in vivo testing, in terms of resource consumption, animal usage, and time, only allows for the testing of a limited number of compounds. Current in vitro systems are limited by screening cells in isolation, underestimating the cytotoxicity of metabolites. In order to address these limitations, the objective of this research is to develop a rapid and efficient in vitro model capable of assessing the toxicological impact of high-N compounds.

Methods: The Integrated Discrete Multiple Organ Co-Culture (IdMOC) system allows for the co-culture of up to 6 discrete organ cell types; demonstrating cell-specific toxicity of parent compounds and of metabolites generated by other cells. In this research, 5 cell lines were used: kidney, liver, lung, heart and vascular endothelium. The high-N compounds assessed through this system were 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN). TNT, with its well documented cytotoxicity, served as a comparative model, while the assessment of DNAN led to a better understanding of its less known toxicity. Cytotoxicity was assessed by viability and functional assays as well as by functional analysis of common regulated genes following microarray analysis.

Results: Following viability assays with the cell lines used in the IdMOC system, the toxicity of DNAN was found to be less than the toxicity of TNT by a factor of 10. Furthermore, results from the functional assays and microarray analysis indicate the effects of TNT and DNAN on the gene expression profiles of the different cell lines as well as the impact of metabolites, leading to a better understanding of the in vitro multi-tissue dynamic of high-N metabolism.

Conclusions: The IdMOC system is expected to play an increasing role in the hazard assessment of high-nitrogen compounds in order to facilitate their safe development and use in insensitive munitions, with the potential for an extended use of the system with other contaminants, natural or industrial.



Occupational Exposure Assessment of 1-Bromopropane

Y. Lin, H. Lee, and C. Ko, Fu-Jen Catholic University, New Taipei City, Taiwan; J. Wu, C. Chang, and Y. Dai, Chang Jung Christian University, Tainan, Taiwan

Objective: 1-Bromopropane (1-BP) has been applied as a metal cleaning agent in manufacture industries since the ozone-depletion substances were banned. Exposure of 1-bromopropane has been reported in relation to peripheral neuropathy. The ACGIH® has classified 1-BP as an A3 chemical. Several occupational disease cases due to the 1-BP exposure have been reported in Japan, the USA and Taiwan. No official PEL and occupational exposure profile of 1-BP are established in Taiwan. This study investigated the exposure profiles of workplaces using 1-BP.

Methods: The 1-BP sampling protocol was modified from OSHA Method 1017 and NIOSH Method 1025. Active samples were collected by drawing workplace air through coconut shell charcoal tubes with personal sampling pumps at flowrate 200 mL/min for 6 hours. All samples were analyzed by GC/MS with a method detection limit of 0.84 ppb. At the time of collection of the personal samples, urine samples were collected. The 1-BP metabolite, n-acetyl-S-(n-propyl)-L-cysteine (AcPrCys) was selected as the biological exposure index (BEI) and quantified by HPLC-MS/MS. The limit of quantitation was 0.023 ng/mL. A total of 100 area and personal air samples and 76 urine samples (before and after the work shift) were collected from three plants.

Results: The 1-BP concentrations of the 95th percentiles of exposure group (cleaning operation) ranged from 31.44 to 41.96 ppm for personal samples. The 95th percentile1-BP concentrations of area samples air ranged from 20.43 to 41.84 ppm. The AcPrCys concentrations in urines were between 11.58 mg/g cre and 4,945.71 mg/g cre before shifts, and the AcPrCys concentrations in urines were from 3.72 mg/g cre to 7,818.26 mg/g cre after shift. The correlation between the after-shift urine AcPrCys concentrations and the 1-BP concentrations of personal air samples was significant (r = 0.679, p = 0.05). This implied that after-shift is a better specimen collecting time for 1-BP BEI, AcPrCys. Meanwhile, an enclosure process was implemented in one of the survey plants and the 1-BP air concentration in the working area was reduced by 70%.

Conclusions: The sampling results exceeded Cal OSHA PEL 5 ppm and ACGIH® TLV®  0.1 ppm. The occupational exposures of 1-BP should receive a high level of attention in Taiwan. Effective engineering controls, respiratory protection program and dermal protection program should be implemented to limit exposures.



Isocyanate Exposure Assessment When a Paint Brush and Roller Are Used to Apply Moisture-Cure Polyurethane Paint

T. Schoonover, Washington State Department of Labor & Industries, Olympia, WA

Situation/Problem: A public mass transit agency established a maintenance program to paint metal surfaces at bus and light rail stations. The agency was concerned about worker and public exposure to airborne isocyanates, chemicals that irritate mucus membranes and are well known to cause occupational asthma. The paint system most compatible with the previously painted shelter frames, doors, and light poles was an isocyanate based moisture-cure primer and paint. Isocyanate exposure is known to be hazardous when polyurethane paints are applied with a spray gun, but less is known of exposure when paint is applied with a paint brush and roller.

Resolution: To guide the agency’s on-site exposure control plan, airborne isocyanate concentrations were assessed under two scenarios. The first scenario was an indoor test environment in which isocyanate concentrations were evaluated in an enclosed non-ventilated test room followed by application in an outdoor test setting. The second scenario was the in situ application of the paint to an outdoor transit station in the public domain. Concentrations of 1,6-hexamethylene diisocyanate (HDI) monomer and three HDI polymers were assessed when two moisture-cure polyurethane paints containing 31-35% isocyanates were applied with a paint roller and brush. Short-term 15-minute samples were taken during paint application in an indoor test environment with no ventilation (n=12); in an outdoor test environment (n=11); and in an outdoor in situ assessment (n=22).

Results: All isocyanates were below analytical limits of detection during the initial test condition in a closed room with no ventilation. Furthermore, all isocyanates were below detection limits in the subsequent outdoor test and during in situ station painting. This is primarily attributed to the roller and brush application method which generate low aerosol and therefore low exposure.

Lessons learned: The paint formulation studied here contains a very low fraction of HDI monomer (0.10%). Thus, there is a low reservoir of isocyanate available to naturally vaporize from the paint can, tray, or from uncured applied paint. If a paint formulation has a higher concentration of isocyanate monomer, isocyanate exposure during roller application may be higher. The non-detectable airborne isocyanate concentrations attributed to the use of roller and brush do not infer that workers do not need proper respiratory or skin protection when doing similar work.



Use of Aggressive Air Sampling for Assessing the Sufficiency of Indoor Firing Range Cleaning for Lead (Pb) Removal

A. Weber and R. Seymour, Army Public Health Center (Provisional), Aberdeen Proving Ground, MD; B. Grace, Public Health Command-Pacific, Camp Zama, Japan

Situation/Problem: In indoor firing ranges, ongoing weapon firing can deposit lead on walls and floors.  These surfaces must be periodically cleaned to maintain surfaces “as free as practicable” of accumulations of Pb as required by the OSHA standard 29CFR1910.1025, Lead. Presently, there are no quantitative occupational exposure limits for Pb on surfaces that can be used to evaluate the adequacy of cleaning. Current lead surface wipe methods for Pb can yield highly variable results which may be inconclusive with respect to showing cleaning effectiveness, particularly when surfaces are porous.

Resolution: Aggressive air sampling, modeled after asbestos post-abatement clearance sampling, was implemented as a more meaningful and practical measure of the effectiveness of indoor range cleaning and the inhalation hazard posed by settled Pb containing dust. Pb air concentrations were measured using National Institute for Occupational Safety and Health (NIOSH) 7300 method.

Results: The Pb air concentrations measured during aggressive air sampling prior to range cleaning were at or above the OSHA permissible exposure limit. The precleaning results exceeded the proposed criteria of 5 µg/m3 or less for a thirty-minute sample collected at 4 L/min. After cleaning, Pb air concentrations were found to be below the method limit of quantitation. Non-detectable concentrations were measured regardless of the porosity of the surface material.

Lessons learned: Using surface wipe sample results to demonstrate the effectiveness of cleaning in shooting ranges is challenging, and the results are difficult to interpret with respect to quantifying hazards. Aggressive air sampling may be a more meaningful tool because it provides a more homogeneous measure of Pb present on surfaces and can quantify Pb which has the potential to become airborne and thus become an inhalation hazard.



Material Substitution of Methylene Chloride/Phenol Paint Stripper

K. Walter, T. Harper, F. Blount, V. Sackmann, and T. Nelsen, Hill AFB, US Air Force, Layton, UT

Situation/Problem: In 2011, the Occupational Safety and Health Administration (OSHA) visited and cited the Air Force Depots for methylene chloride overexposure during paint stripping of aircraft flight controls. Material substitution had been attempted many times, but had failed due to lack of treatability of the waste water or high disposal costs.

Resolution: Several engineering controls were implemented, however, the controls were unable to reduce the exposure below the Permissible Exposure Limit/Action Level. After four rounds of material substitution trials with undesirable results, a new formulation of a of a non-methylene chloride containing paint stripping product was tested and passed all of the test requirements.

Results: This new formulation passed all three important tests for implementation: It was listed on the Air Force Corrosion Prevention and Control Office Qualified Products List, it removed multi-layer paint systems, and it was treatable by the Industrial Wastewater Treatment Plant at Hill AFB. Through testing, the new paint stripper removed coatings in a similar timeframe as the previous stripper. Rinse water was collected and a treatability test was performed at the wastewater treatment plant. This test was performed at 5% of total plant flow and showed no adverse effects. Furthermore, this material substitution significantly reduces chemical loading at the Industrial Wastewater Treatment Plant, which would reduce environmental regulatory risk and treatment costs. Finally, the new material did not contain an OSHA’s Expanded Standards chemical, providing a reduced exposure to employees, and OSHA regulatory risk.

Lessons learned: Integrating the entire implementation team to include engineering, EHS, and subsidiary processes allowed for validating the entire process from cradle to grave. In addition, the team’s effective communication with the material manufacturer has aided in the successful process substitution. As a result of this project, these efforts have reduced chemical exposures to personnel and decreased our regulatory risk.​