The following discussion of various occupational exposure criteria provides a framework to evaluate the exposures that occurred during the Gulf War. A direct comparison of the exposures during the Gulf War to these standards is theoretical since no workplace measurements were taken during the war. These standards are discussed in detail below and in the applicable cited references, but the most important aspect of this discussion is that there were no measurements taken during the Gulf War for direct comparison.
Nevertheless, two conclusions can be drawn. First, current Army and federal occupational and safety directives clearly call for the use of personal protective equipment (PPE), including respiratory protection, during polyurethane (CARC) painting operations. Based on experience and professional judgment of the health and safety professionals monitoring the CARC painting operations in-theater, unprotected personnel who were spray painting CARC in the conditions documented in the Gulf were exposed to potentially hazardous conditions.
A. Occupational Safety and Health Requirements
Most of the standards established by occupational health authorities are based on routine time-weighted exposures over a working lifetime, typically 8 hours per day, 40 hours per week. Two exceptions are the short-term exposure limit (STEL) and the ceiling limit.
The STEL is defined as a 15-minute time-weighted average that should not be exceeded at any time during the workday. The STEL allows for brief excursions above the 8-hour time-weighted average, as long as the daily average exposure is less than the standard. In contrast, the ceiling standard is a limit that should never be exceeded at anytime during the workday.
The Occupational Safety and Health Administration (OSHA) establishes legally enforceable occupational exposure limits to substances. OSHA sets these standards in the form of permissible exposure limits (PELs). Currently, OSHA does not have a permissible exposure limit for HDI as either a monomer or a prepolymer. (Note: HDI may be present in CARC as either a monomer or a partially reacted prepolymer, also called an oligomer. This is significant because the monomer is more volatile and usually exists as a vapor after CARC has been sprayed. On the other hand, the prepolymer is less volatile and is usually present as an aerosol mist or droplet after CARC has been sprayed.)
The National Institute for Occupational Safety and Health (NIOSH) developed a recommended exposure limit (REL) for HDI monomer of 35 �g/m3 or 0.005 parts per million (ppm), but has not established a recommended exposure limit for the HDI prepolymer. The NIOSH REL is a time-weighted-average value for a normal working lifetime (up to 10 hours per day, 40 hours per week, for 40 years). NIOSH also established a ceiling value of 140 �g/m3 (0.020 ppm) for HDI monomer. A ceiling value is a concentration that should not be exceeded during any part of the working exposure; if instantaneous monitoring is not feasible, the ceiling must be assessed as a 10-minute time-weighted-average (TWA) exposure for HDI. Though the NIOSH recommended exposure limits have undergone study, they have not completed the regulatory review process to become legally enforceable OSHA standards.
The American Conference of Governmental Industrial Hygienists (ACGIH) has also established threshold limit values (TLV� ). [Note: Threshold limit values are registered trademarks of the American Conference of Governmental Industrial Hygienists.] Threshold limit values refer to airborne concentrations of substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse health effects. However, because of wide variation in individual susceptibility, a small percentage of workers may experience discomfort from some substances at concentrations at or below the threshold limit value (TLV� ). A smaller percentage may be affected more seriously by aggravation of a pre-existing condition or by development of an occupational illness. The TLV� for HDI monomer is 34 �g/m3 (0.005 ppm). The level of exposure above the threshold determines the severity of the adverse health effect. The American Conference of Governmental Industrial Hygienists considers threshold limit values to be recommendations to be used as guidelines for good practice.
An exposure limit for the HDI prepolymer has not been established by OSHA, NIOSH or ACGIH. Oregon is the only state OSHA program that has established an exposure limit. Oregon's 8-hour time-weighted average limit for HDI prepolymer is 500 �g/m3 with a ceiling level of 1000 �g/m3. In addition, Bayer Chemicals, a leading producer of HDI, established a corporate recommended ceiling level for HDI of 0.02 ppm.
Despite the prevalence of occupational health and safety exposure limits and regulations in the military workplace during peacetime, regulations from the Occupational Health and Safety Administration (OSHA) do not apply in combat situations. Though the Department of Defense states that all DoD personnel worldwide fall under OSHA regulations, exemptions or exceptions from this oversight for military personnel apply in military-unique operations and workplaces (e.g., a wartime setting). However, the Department of Defense retains its obligation to protect the health of its servicemembers at all times.
B. Safety Guidance Prior to Operation Desert Shield/Storm
When troops and vehicles deployed to the Gulf for Operation Desert Shield in 1990, a detailed body of doctrine already existed for the use of CARC and the establishment of paint sites. Military technical guides, manuals, and bulletins, as well as OSHA regulations, clearly detail the necessary procedures involved in establishing CARC painting operations.
Army Technical Guide Number 144, "Guidelines for Controlling Health Hazards in Painting Operations" clearly spells out the procedures for proper set-up and testing from the initial stages of the operation. As Technical Guide No. 144 explains, " statistically valid personal samples must be collected for HDI ... results determine the required types and level of respiratory protection and engineering controls." Not only is personnel testing required for paint site set-up and annual monitoring, but also when any change occurs in an existing sites process, controls, or personnel. Such change requires additional environmental and personnel monitoring.
All types of monitoring are performed in conjunction with a standardized medical surveillance process. A pre-placement, or baseline health evaluation, of individuals is the first step in medical surveillance. Baseline determination involves three main steps: 1) determining an individuals medical and occupational history, with emphasis on prior exposure to HDI, allergies, respiratory disease, and smoking; 2) a physical examination with attention to the respiratory system; and 3) clinical laboratory tests (e.g., chest x-ray, pulmonary function tests). An annual physical examination and a pulmonary function test should follow the establishment of baseline data.
The use of proper respiratory protection, particularly in spray painting operations, is vital when working with CARC. Due to the significant toxicity and lack of odor-threshold warning properties associated with HDI, OSHA dictates the use of only positive-pressure air-supplied respirators. [191,192] This guidance is echoed by the National Institute for Occupational Safety and Health (NIOSH), and the Department of the Army. A positive-pressure air-supplied respirator is one in which the pressure inside the mask is higher than the outside environment. Clean, supplied air constantly flows into the mask from a tube for inhalation, while exhaled air exits the mask through vents. Either a full face respirator or a half-face respirator with goggles is appropriate.
Unlike spray painting operations, brush or roller painting does not cause significant aerosolization of paint constituents, and exposures to HDI are at much lower levels. In large open bays and outdoors, the potential for overexposure when using brush and rollers is remote.
Workers painting or mixing CARC must use not only respiratory protection, but they must wear eye protection and clothes that provide full skin coverage and protection from contact with CARC. Gloves and coveralls are particularly important, especially gloves. As noted earlier, HDI is both a skin and eye irritant.
Beyond physical personal protective equipment, training and the dissemination of information on the hazards associated with CARC application also reduce the risks of worker exposure. Material safety data sheets (MSDS), which detail hazards, protective measures, and chemical formulation, accompany all batches of paint. Federal regulation requires that material safety data sheets be filed in a location readily accessible to workers exposed to a hazardous substance, such as CARC. Federal law also requires the use of material safety data sheets in training new workers.
In 1988, the US Army Safety Center produced a safety support pamphlet about CARC painting that was available as a reference for civilian and military safety offices. This comprehensive guide discusses the required safety equipment and procedures for a CARC painting operation. The pamphlet also explained each of the potential components of a CARC systemthe primers, solvents, and topcoatsand the dangers of each. (Primers were not used in the painting process during Operations Desert Shield/Storm.) In addition, the pamphlet included suggestions on ways that safety professionals could train personnel to work safely with CARC.
C. Material Safety Data Sheets
The military uses material safety data sheets (MSDS) to ensure that health and safety information associated with a product is available to the users. The military also uses MSDSs to ensure full disclosure of information regarding the types of raw materials used in the formulations. Material safety data sheets accompany each product. Federal regulations require that all material safety data sheets be filed in a location readily accessible to workers potentially exposed to hazardous substances, such as CARC. In practice, the material safety data sheets are usually taken from the package of paint cans and then filed.
D. Hazard Communication Program
Military regulations and standard operating procedures require conformance to, and compliance with, public law and national consensus standards for the hazard communication program (HAZCOM). DoD Instruction 6050.5, the Department of Defense Hazard Communication Program, outlines responsibilities and procedures for a comprehensive hazard communication program that includes training for DoD personnel in potential occupational health hazards. Department of Defense personnel are to be informed of safe work practices and are to be trained in the selection, use, and availability of personal protective equipment (PPE) to prevent injuries and illnesses. It states that it is the Department of Defense policy to protect personnel from the adverse effects of workplace hazardous materials and waste, to reduce chemically related injuries and illnesses, and to establish and maintain a standardized hazardous materials information system. Each service and component is required to establish and maintain hazard communication programs that conform to the requirements of DoD Instruction 6050.5 and comply with the Occupational Safety and Health Administration (OSHA) hazard communication requirements.
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