## Workers' Exposures to n-Propyl Bromide at an Aerospace Components Manufacturer

Kevin W. Hanley, MSPH, CIH, REHS/RS Kevin Dunn Ron Sollberger

Industrywide Studies Branch Division of**Surveillance~** Hazard Evaluations and Field Studies National Institute for Occupational Safety and Health Centers for Disease Control and Prevention US Public Health Service Department ofHealth and Human Services

IWSB 232.12

November 2006

### Abstract The National Institute for Occupational Safety and Health (NIOSH) conducteda field study at an aerospace componentmanufacturing plantwhere n-propyl bromide (nPB) was used as avapor degreasing solvent. Workers' breathing zone and exhaledbreath concentrations ofnPB and isopropyl bromide (iPB), and urinary metabolite concentrations ofbromide andpropyl mercapturic acid were measured. n-Propyl bromide has been marketed to replace ozone depleting solvents 1,1,I-trichloroethane and freons®, as well as suspectcarcinogens trichloroethylene and methylene chloride; chemicals that were commonly used in industry. Very little data are currently available to evaluate 

### human exposure to nPB. However, there is concern that nPB may be a hematological, reproductive, or neurological toxin, based on analogy to otherbrominated-propanes, animal toxicity studies, and a limited number ofcase studies. Full-shiftexposure to nPB in air samples collected in workers' breathing zones ranged from 0.19 to 2.6 parts per million (ppm). All ofthe workers were exposed to nPB at levels belowthe American Conference ofGovernmental Industrial Hygienist (ACGIH) Threshold Limit Value® (10 ppm) as well as the industrial guideline of25 ppm publishedby the EPA in theirproposed rulemaking to acceptnPB underthe Clean AirAct. Isopropyl bromide was not detected in either the air orbreath samples. Exhaled breath concentrations ofn-propyl bromide ranged from ND to 0.13 ppm and ND to 0.38 ppm, respectively, for pre-shift samples and post-shift samples. Average urinary bromide concentrations were approximately 77% higher for workers than for unexposed control subjects who were not employedby the company. Twenty-fourhour average propyl mercapturic acid concentrations measured in urine specimens from workers were over an order ofmagnitude higherthan that measured in control samples. Dermal absorption mayhave contributed to some ofthe workers' exposure in addition to inhalation exposure. Workers with the lowest breathing zone concentrations ofnPB had urinary metabolite levels similarto those measured in control specimens. At this time, the healthsignificance ofthese levels ofurinary metabolites is unclear. Recommendations include, but are notlimited to, substitution ofnPB solvents with a less toxic solvent (iffeasible), periodic exposure monitoring, use ofgloves that are impermeable to nPB, and routine medical examinations.

1

### Introduction The Industrywide Studies Branch ofthe National Institute for Occupational Safety and Health (NIOSH) conducted a field study at Hamilton Sundstrand, an aerospace component manufacturing plant in Rockford, Illinois onFebruary 23-25, 2004. Atthis facility, n-propyl bromide (nPB) was used as a vapor degreasing solventto remove oils, chemicals, and dirtfrom various parts and components priorto the inspection, surface treatments, painting, and assembly. In this research study, we measured workers' breathing zone concentrations to nPB and isopropyl bromide (iPB), an impurity, with standard air sampling methods in conjunction with new methods for measuring exhaledbreath and urinary metabolites. 

### Background The toxicity ofnPB, also named I-bromopropane (CAS no. 106-94-5), is notfully understood as there is limited information inthe published literature. The Environmental Protection Agency (EPA, 1999; 2003) is evaluating nPB as an alternative to ozone-depleting solvents for vapordegreasing and liquid cleaning ofmetal, precision, and electronic components as well as for use as a solvent in aerosol products and adhesives. n-Propyl bromide has been marketedto replace 1,1,I-trichloroethane, freons®, and suspect carcinogens trichloroethylene and methylene chloride, chemicals that were commonly used in industry. Very little data are currently available to evaluate 

### human exposure to nPB. However, based on analogy to otherbrominated-propanes, animal toxicity studies, and a limited number ofcase studies, there is concern that nPB may be a hematological (blood), reproductive, orneurological toxin. (Referto Attachment I for more detailed informationregarding the toxicity ofnPB and iPB.) Based on the uncertainty regarding the toxicity ofnPB, the Occupational Safety and Health Administration (OSHA) andNIOSH requested the National ToxicologyProgram (NTP) to evaluate the toxicity ofthis chemical (OSHA, 1999; NTP, 2004). The absence ofnPB exposure assessment information has promptedthis occupational exposure study to evaluate industrial exposures to nPB by measuring workers' personal breathing zone, exhaled breath, and urinary metabolite concentrations. 

### Process Description Hamilton Sundstrand is a subsidiaryofUnited Technologies, a diversified multi-industry corporation which manufactures aviation engines; power fuel cells; elevators and escalators; climate control, fire and security systems; and components for industrial and aerospace applications. The company thatparticipated in this study is one ofthe largest global suppliers of advanced aerospace systems for commercial, regional, corporate, and military aircraft as well as for sea and spacecraft. This companyhas 10 manufacturing sites inthe U.S. and additional facilities in Puerto Rico, SoutheastAsia, and throughoutEurope. Electric and flight control systems were the primary products manufactured atthe Rockford site including, butnot limited to, power generation, distribution, and control systems; constant speed drives; auxiliary generators; electric power conversion equipment; flight control actuation and electro-magnetic systems. 2Atthis site, the main campus consists ofthree majormanufacturing plants, with another industrial plant approximately two miles away. Twenty-five hundred employees work at these facilities; seven hundred workers are represented bythe United Automobile Workers, UAW local 592. A nPB-based solvent (Leksol, Amity International, Inc.) is used as a vapor degreasing agent in six departments to remove oils, chemicals, and dirt from casings, drive components, and other parts necessary for inspection, surface treatments, painting, and assembly tasks. Eightvapor degreasers ofdifferent makes, models, and capacities are available; however, three ofthe units are seldom used, only a few times permonth. The production schedule for this company is dictated by customerorders, typicallyin small quantities ofless than 10-20units. As such, vapor degreasers are not continuously operated, ratherparts are cleaned in batches on an "as-needed" basis. Although approximately 100 employees have access to the degreasers, only about 30 routinely cleanparts. Vapor degreasers utilize a refrigerated cooling coil around the top ofthe interior ofthe vapor chamber, which condenses nPB vapor into liquid droplets on the cool surface ofparts to remove surface contamination. Excess solventdrips back into the solvent sump andis recycled as the parts slowly ascend from the vapor to condensing zones. A secondary function ofthe cooling coil is to control solventvapor emissions by "capping" the heatedvapor zone with a refrigerated air space, typically six to twelve inches in height. Some ofthe nPB degreasers also had a chamber coverthat was closed when the degreaser was notin use, and mechanical hoists to remove the partracks at a programmed speedto minimize excessive vaporfrom being carried out ofthe unit. Most ofthe parts cleaning occurredinplant 6 on the main campus for Assembly Prep (one worker was the principal user ofthe degreaser); Repair-Overhaul (two workers); Electric Systems

- Paint & Wire departments (two shifts, six workers per shift), and atplant 1 for MXM cell/corrosion treatment and non-destructive testing (three shifts, six or seven per shift); and Engine Control Systems

- Paint 

### & Wire departments (two shifts, six workers per shift).
In the Assembly Prep area, parts needed for the main assembly floor are cleaned in a small (15" x 46") open-topped Delta Sonics vapor degreaser which was equipped with ultrasound vibration to aid with cleaning, and a back plenum-slotexhaustventilation system for additional contaminant control. Inthe Repair-Overhaul room, an open-topped, medium size**(~2.5'** x 4') degreaser (Branson B3550R) was used for non-destructive testing which included fluorescent dye penetrant inspections. A chamberlid and local exhaust ducting was provided above the condensing zone to assist with vapor emission control. Final assembly ofcomponents were conducted inthe Paint & Wire locations for both the Electric Systems and Engine Control Systems departments. Assemblers'job tasks included degreasing, painting, and fastening wires and identificationplates priorto shipment. Spray painting was performed with methyl ethyl ketone (MEK) and other organic solventbasedpaints in large ventilated spray booths; acetone, Stoddard solvent, and isopropyl alcoholwere also presentin 

### 3these locations for clean-up activities. The Paint& Wire vapor degreasers were large semienclosed units because ofthe size ofsome components. Components were loaded into baskets (-2.5 x 4') orcrates and placed into an open framed rack. The rack was mechanically hoisted up and overthe external wall ofthe degreaseI', lowered into the vapor zone, and similarly removed atprogrammedrate for effective cleaning and to reduce solventcarry-out. A similarvapor degreasing unitwas present in the MXM Cell area, Plant 1 to service anticorrosion surface treatment andnon-destructive testprocedures. Surface treatments were applied by immersing parts into a series ofchemical solutions and water rinses with an overheadhoist. Phosphate coating was the principal anti-corrosion tr.eatment;chemical solutions includedTurco alkaline rustremover, sodium hydroxide, sodium fluoride, andphosphate fluoride. A number of non-destructive testprocedures were employed in the 

### MXM Cell room to evaluate the integrity ofmetal casings and housings: magnaflux (magnetic particles in Stoddard solvent); zyglo (fluorescentpenetrant dye); metalnox with ultrasound; and X-ray radiation. The vapor degreaser used in MXM Cell was very similar in size and designto those installed inthe Paint & Wire locations. Even thoughthe degreaser was enclosed, the large size and shape ofsome casings caused solventto pool in the parts and subsequently carried-out ofthe vapor control zone. As a response to this problem, an auxiliary push-pull slotted local exhaustventilation systemwas installed on the sides ofthe exitconveyorto reduce workers' exposures to nPB vapors. The slot opening in the suctionplenum was approximately 4" x 5'

. Personal protective equipmentused by employees included nitrile, neoprene, orbutyl rubber gloves, safety glasses, and safety shoes. Organic vapor half-face piece respirators were available for protection against high nPBexposures such as draining spent solvent from the degreaser sump and replenishing it with Leksol. Chemical aprons, and face shields were also required when using the degreaser in MXM cell room. Hearing protection was also available as specified by the Health & Safety department. 

### Evaluation Criteria Atpresent, occupational exposure limits (OELs) for nPB are not available from either OSHA (2006) orNIOSH (1992), and suggested manufacturers' guidelines are inconsistent, ranging from 10 to 100parts per million (ppm) (Great Lakes Chemicals, 2005; Enviro-Tech International, 2005). The EPA initially reviewed industry-sponsored animal studies and suggested that 50 to 100 ppm should provide adequate protection, but cautioned thatthis was a preliminary decision since it was based on limited data with considerable uncertainty (EPA, 2000). This proposal was largely based on hepatic toxicity observed in rats, not on reproductive, hematopoietic, or neurologic effects. Afterreviewing industry studies (Clintrials Biorecherchesl997a, 1997b; WIL Research Laboratories, 2000) and published literature, Rozman and Doull (2002) concludedthat neurotoxicity is the most sensitive endpoint and an OEL for nPB in the range of60 to 90 ppm shouldprovide an adequate margin ofsafety. On June 03, 2003, the EPA published aproposedrulemaking to accept nPB as a replacement solvent for ozone depleting substances for general metals, precision, and electronics cleaning, aerosol products, and adhesives (EPA, 2003). In this proposedrule, the EPA recommends an 

### 4industrial exposure guideline for nPB of25 ppm over an 8-hrwork shift. The proposed rulemaking is currently being re-assessed bythe EPA. Albemarle Co. (2003), one ofthe domestic suppliers ofnPB solvents, also recommends an exposure guideline for nPB equal to 25 ppm as an 8-hourtime weighted average (TWA) concentration. In 2005, ACGIH published a recommended Threshold LimitValue® (TLV) for nPB as a 10 ppm, 8-hr TWA based on suspected neurological toxicity (ACGIH, 2006). As one can see from these exposure guidelines, the OELs for nPB recommended by different organizations vary by an order ofmagnitude. Following a case study ofreproductive and hematological health effects in workers exposed to iPB in an electronics plant (Kim et aI., 1996; Park et aI., 1997), the Republic ofSouth Korea promulgated an OEL for iPB of 1 ppm, measured as an8-hourTWA. No other OELs are presently published for iPB. Occupational exposure criteria fortwo ofthe urinary metabolites of nPB which were analyzed atthese facilities (e.g., bromide and propyl mercapturic acid) are currently unavailable. 

### Methods
In this research study, we measured nPB inhalation exposures with standard air sampling methods in conjunction with new methods for measuring exhaledbreath and urinary metabolites. Employees voluntarily participating in the study were informed ofthe study requirements and provided theirwritten consent in accordance with Human Subjects Review Boardprotocol. A total of11 workers were included, each ofwhom worked with orwas expectedto be in the vicinity ofvapor degreasers using nPB. The workers also wore a light-weight air sampling device on 2 consecutive days, providedpre- and post-shiftexhaled breath samples, and all of their urine specimens over a 48-hourperiod. The air and breath samples were analyzed for nPB as well as iPB, a low level contaminant in nPB solvents. The urine samples were analyzed for bromide (Br) ion and propyl mercapturic acid (PMA), also calledN-acetyl-S-(n-propyl)-Lcysteine. Personal breathing zone exposures and exhaled breath samples were collected with Anasorb carbon molecular sieve (CMS) sorbenttubes. The sorbenttubes were desorbed with 1 milliliter (ml) ofcarbon disulfide, and analyzed for nPB and iPB by gas chromatography with flame ionization detection (GC-FID) viaNIOSH method 1025 (NIOSH, 2003a). The limit ofdetection (LOD) for this method is 1**~g** which equates to a minimum detectable concentration (MDC) of 0.017 ppm in air using the maximum recommended air sampling volume of 12liters and a MDC of0.066 ppm in an exhaled breath volume of3 liters. Qualitative evaluation ofskin contact potential was conductedby visual observation of job tasks since effective quantitative skin exposure measurementmethods do not exist for compounds, such as nPB, that are volatile and readily penetrate intact skin. To obtain data on nPB metabolites excretedby humans, all ofthe workers' urine voids over a 48-hourperiod were collected, including the amountexcreted while away from work. The specimens were collected as composite samples over sequential time intervals: 1) atwork, 2) after work but before bedtime, and 3) upon awakening. Each sampling survey was intended to occurover a 48-hourperiodthat started atthe beginning ofthe work week (Monday, pre-shift), 5following a weekend ofno exposure and end before the work shift on Wednesday. [However, three (out offour) employees in plant 6, and one (out ofseven) employees 

### in plant 1 worked withnPB overthe weekend.] Forcomparison, single "spot" control samples were collected from twenty-one unexposed office workers who were not employedby this company. Urine specimens were collected in nitric acid rinsedNalgene® bottles [highdensity polyethylene (llDPE)] and immediately chilled in 10 quart coolers with gel ice that were individually.supplied to each participant. Upon the end ofthe collectionperiod, three-25 ml sample aliquots were dispensed into nitric acid rinsed HOPE bottles and immediately frozen on carbonic .acid (dryice). The total urine volume for this collectionperiod was also measured with a graduated cyclinder. In additionto Brand PMA, the specimens were also analyzed for creatinine (cr). 

### Bromine Bromine (Br) was measured with.inductively coupledplasma/mass spectrometry (ICP/MS; VarionUltra-mass 700) using yttrium as an internal standard(Allain et aI., 1990; Ichihara et aI., 2004; Kawai et aI., 2001). The LOD for bromine was 90 micrograms per liter (Jlg/I). One ml of each sample was diluted to 10 ml with 1% nitric acid priorto analysis. Analytical.standards and quality control samples were preparedusing Uri-sub, a synthetic urine solution. This was necessarybecause background concentrations ofbromine may be presentinpooledurine from the general population. 

### Propyl mercapturic acid The urine specimens were analyzed for PMA, one ofthe majormercapturic acid metabolites of nPB (Grenby and Young, 1960; Jones and Walsh, 1979). Fourml aliquots ofthe urine specimens were loaded onto a solidphase extraction cartridge, rinsed with three ml ofa methanol-acidified water mixture (pH = 3); PMA was then extracted in four ml ofacetone, dried undernitrogen, and reconstitutedin one ml ofmethanol. Analysis was performedusing high performance liquid chromatography (HPLC) with electrospray ionization-tandem mass spectrometry (ESI-MS/MS) for improved sensitivity and specificity (e.g., confirmation of chemical identity). 

### Creatinine Creatinine was analyzed using Sigma diagnostics testkit, procedure #555. Room temperature urine specimens were diluted by a factor of20 (or 40 ifvery concentrated) and mixedwith six ml ofalkaline picrate. After 10-15 minutes, color analysis ofthe creatinine-picrate complex was performed with a spectrophotometer (Milton Roy Spectronic 20 D). A 0.2 ml aliquot ofacid reagentwas then added and the specimen was re-analyzed afterfive minutes; positive results from the second analysis were subtracted from the first measurements as itis due to interfering compounds. Creatinine is a protein by-productexcreted in urine due to the metabolism ofcreatine from muscle exertion. It is often used to adjusturine data due to different levels ofphysical activity, 

### 6hydration, and urine concentrations between differentindividuals. Theurine data inthis report, however,are only presented as unadjusted concentrations, eithermg/l or p.g/l for Br and PMA, respectively. Once the data are compiled from multiple sites inthis study, the urine data will be adjusted ("normalized") for creatinine (mg Br/gm creatinine or p.g PMA/gm creatinine) for publication in scientificjournals. 

### Results Table lA presents the air sampling results collected inworkers' breathing zones overtwo full work shifts. Table 1B and 1C provide the data stratified separately for eachplant. The TWA concentrations for alljobs in bothplants ranged from 0.19 to 2.6 ppm withdaily averages of0.99 and 1.2 ppm. All workers' TWA exposures were less than 10 ppm. Iso-propyl bromide was not detected in any ofthe air samples. The two highestTWAs occurred in MXM cell department on a day whenthe degreaserwas used thirteen times. Although the highest exposures occurred in MXM cell (plant 1) when conducting non-destructive testing, the average TWA exposure in plant 6 was greaterthan for plant 1 on both days (1.5 versus 0.69 and 1.5 versus 1.09, respectively for day 1 and day 2). One reason may be thatthree ofthe Assemblers who were monitored in plant 1,collectively used the degreaser once and only walked neartheses areas on a few occasions. Workers in plant 6 reported infrequentuse ofthe degreasers because they worked overthe weekend. Tables 2A, 2B, and 2C provide a summary ofthe breath concentrations for nPB, respectively for both plants combined, plant 1, and plant 6. The nPB concentrations measured in the post-shift samples ranged from non-detectable to 0.38 ppm. Ten (out of22) samples had detectable levels ofnPB in the pre-shift samples, ranging from ND to 0.13 ppm. Isopropyl bromide was not detected in any ofthe breath samples. The average breath concentrations measured in each building were nearly identical. However, nPB was detected in low concentrations (0.022-0.11 ppm) from air samples collected inthe nurse's office during breath collectionperiods in Plant 1 butnot Plant 6. This may have caused sample contamination. The average Br concentration from urine samples collected before the work-weekbegan was 8.8 milligrams per liter (mg/l) for bothplants combined (Table 3A). For comparison, the average Br concentration was 4.0 mg/l in spot samples from control subjects who were not employed by this company. Moreover, the 24-hour.average concentrations ofurinary Br for all workers were approximately 77% greaterthanthe control subjects. In plant 1, the average 24-hourBr concentrations were similarto the control average, butwere two to three times higherin plant 6. The data for PMA are provided in Table 4A, 4B, and 4C, which show a similartrend as the average before work week concentrations for workers was approximately 44% higherthanthe average calculated from control specimens. Furthermore, the average 24-hourconcentrations of PMA from all workers were .an order ofmagnitude higherthan controls for both work days. The mostheavily exposed workers in plant 6 had the highestPMA inurine concentrations, however, the average 24-hourPMA levels in plant 1 were also at least four times as high as controls. The potential for solvent splashing and dermal contact exists with vapor degreasing processes, especially inMXM cell department because ofthe shape ofthe parts. The gloves observedto be 

### 7used inthese departments (nitrile and neoprene) do notprovide adequate protection for more than a few hours. Statistical analyses were not conducted for the data collected at this site since only 11 workers participated 

### in the monitoring. Statistical analyses will be performed after all ofthe data collected at separate sites are pooled into larger databases. 

### Conclusions

• All ofthe workers' full-shift exposures were below the industrial guideline of25 ppm proposed by the EPA as well as the ACGIH TLV® of 10 ppm.

• The condensing coils and exhaustventilation provided for the vapor degreasers is relatively effective in controlling nPB air emissions from these operations in bothplants, given the observedproduction rates.

• Workers' exposures to iPB were not detected with a minimal detected concentration (MDC) well below 1 ppm, the only occupational exposure limit available (publishedby South Korea).

• The post-shiftbreath monitoring showedmeasureable levels ofnPB butnot iPB.

• With the exception ofone sample, breath concentrations ofnPB were not detected inpreweek samples. Dermal contact with recently degreasedparts may contribute to the workers' exposures. nPB is appreciably absorbed through workers' intact skin, which contributes to their overall absorbed dose. Average 24-hour concentrations ofthe urinary Brwere 77% higher for workers than for control subjects. Average 24-hour concentrations ofthe urinary PMA measuredin worker specimens were at least 10 times as high as PMA concentrations measured in control specimens. The conclusions drawn are based on the data from the grouped population ofworkers. These data demonstrate that workers using degreasersare exposed to and are excreting nPB metaboles. However, the health significance ofan individual's urine metabolite level is uncertain. 

### Recommendations Human health effects from exposure to nPB are notfully understood as there are only a few reports in the published literature. The occupational exposure criteriaof25 ppm suggestedby the EPA and some solvent manufacturers are largely based on limited data observed in animal 

### 8

### toxicity studies. As additional scientific informationbecomes available, the OEL currently proposed may, in fact, be lowered. Therefore, NIOSH scientists believe it is prudentto reduce occupational exposure ofnPB to the lowestfeasible levels. To reduce the risk ofhazardous exposures inthe workenvironment, industrial hygiene principles incorporate the following hierarchy ofexposure control, in decreasing orderofpnbference (and effectiveness): i) Eliminate atoxic substance by substituting itwith a less toxic one orbyprocess changes, ii) Install engineering controls to remove orreduce the airborne contaminants, preferably atthe point ofemissionusing: local exhaustventilation; isolation ofcontaminant emissions away from workerpositions; orby process changes, iii) Use ofadministrative controls to reduce individual exposures by altering orrotating job tasks and work schedules, thereby reducing high exposure durations, and iv) Use ofpersonal protective equipment (PPE), such as respiratory protection, gloves, aprons, etc., to reduce the absorbed dose from potential exposure. Although PPE is frequently used because it is a cheaper and easiermethod ofcontrol, itis the least desirable because it is not always effective. NIOSH policy is thatPPE should only be used when engineering controls are infeasible; during the interim period when engineering controls are being installed orrepaired; orwhen engineering controls are not effective inreducing exposure belowhazardous levels. More specific recommendations to minimize workers' exposures to nPB atthis facility are provided below: 1. Eliminate nPB based solvents iffeasible by using a less toxic substitute. It 

### is advisable to consult with technical experts and solvent distributors to evaluate if there are any suitable alternative solvents that are less toxic which perform in accordance with engineering specifications. 2. Employee exposures to nPB should be periodically re-evaluated. Ifmonitoring results exceed relevant criteria, install engineering controls consisting oflocal exhaust for the degreaser and provide make-up air ventilations systems to reduce airborne nPB concentrations. Design specifications are available inthe ACGrn Industrial Ventilation Manual, 25th 

### edition (2006). In addition, a routine maintenance schedule mustbe implementedto ensure effective performance of the equipment. 3. Respiratory protection should be provided for those workers who desire to use it when operating the vapor degreaser orifthe controls are noteffective inreducing exposures sufficiently. OnlyNIOSH approved airpurifying respirators with organic vaporcartridges orNIOSH approved air suppliedrespirators shouldbe used. The use ofrespiratoryprotectionrequires the implementation ofa comprehensive respiratory protectionprogram in accordance with OSHA regulations (29 CFR 1910.134) andNIOSH recommendedprocedures (NIOSH, 

### 91987). A minimal acceptable program mustbe managedby a competentperson and include: written procedures; proper selection; usertraining; routine cleaning and inspection; proper storage; surveillance ofwork conditions and worker exposures; program audits; medical determination ofuserfitness; and use of approved respirators. 4. n-Propyl bromide readily penetrates intact skin and common glove materials. The relatively low TWA air concentrations coupled with high PMA metabolites suggests that dermal contact and absorption ofnPB is substantial for some workers using the vapor degreasers. When skin contactpotential with nPB or parts recently removed from the degreaseris high, appropriate gloves, arm sleeves, aprons or otherPPE should be used as appropriate. Solvent manufacturers recommend use ofmultiplelayer laminates for protection against nPB. These include, but are not limitedto, VitonTM, 4H (pE/EVAL)TM, and Silver ShieldTM. Othermore common glovelPPE materials (e.g., latex, nitrile, neoprene, butyl rubber, PVC, etc.) do not adequately preventnPB from penetrating the PPE material for more than 30 minutes to a few hours. This may include time after the glove is contaminatedeven though it is no longer worn by a worker. The more common gloves may still be required for protection against other chemicals used inthese areas. Hence, itis advisable to consult with technical experts and safety supply vendors to select an array ofgloves needed in these departments. Periodic training ofemployees is importantto preventthem from using the wrong gloves for different applications. 5. Ifalternative solvents are not feasible, use nPB solvents thathave the lowest iPB contamination as is possible. Based on the non-detectable iPB results, it appears that nPB solvents used at your facilities do not contain excessive iPB contamination. The ASTM (2001) standard for iPB contamination in nPB solvents is 0.10%. In the EPA proposedrulemaking (2003) to accept nPB solvents, a use restriction includes using nPB solvents with an iPB contamination not exceeding 0.05%, before blending into products. It is advisable to confirm that the nPB solvents at your sites meetthis criterion. 6. Company management must maintain an awareness ofthe latest scientific information regarding occupational exposure guidelines for nPB as well as relevanthealth, safety, and environmental standards from regulatory agencies. 7. Employees potentially exposed to nPB should be provided withroutine medical examinations. Reports ofhealth effects shouldbe referred to a health care providerwho specializes in occupational orenvironmental medicine.

10Table lAo Summary ofworkers' TWA8 air sample concentrations ofn-propyl bromide and isopropyl bromide for plants I and 6 combined. 

### Hamilton Sundstrand Rockford, IL 

### NationalInstitute for Occupational Safety and Health Centers for Disease Control and Prevention IWSB232.12 TWA Air Concentration (ppml Chemical Measure (n = 11) Day I Day 2 Average 0.99 1.2 nPBc Range 0.19

- 2.1 0.11-2.6 Average



### - - iPBd Range NDe ND

Table lB. Summary ofworkers' TWA8 airsample concentrations ofn-propyl bromide and isopropyl bromide for plant 1. TWA Air Concentration (ppml Chemical Measure (n= 7) Day 1 Day 2 Average 0.69 1.1 nPBc Range 0.19 -1.1 0.11- 2.6

iPBd Average

- 

### - Range NDe ND

11Table IC. Summary ofworkers' TWAa air sample concentrations ofn-propyl bromide and isopropyl bromide for plant 6. 

### Hamilton Sundstrand Rockford, IL 

### National Institute forOccupational Safety and Health Centers for Disease Control and Prevention IWSB232.12 TWAAir Concentration (ppmr Chemical Measure (n == 4) Day 1 Day 2 Average 1.5 1.5 nPBc Range 0.82

- 2.1 1.3 -1.6 Average

- - iPBd Range NDe 

### ND

Footnotes for Tables lA, IB, and Ie: a) TWA = time weighted average. It is used when multiple samples are collected OVerthe work shift to calculatethe average exposure concentration "pro-rated" for time. Example: TWA = [(time 1 x cone. 1) + (time 2 x cone. 2)

... + (timei x cone.i)] + total time for both sample 1 and 2 plus all additional samples (i) b) Units are in parts per million by volume; the amount ofbromopropane per 1 million parts ofair. c) nPB= n-propyl bromide (also called I-bromopropane). d) iPB = isopropyl bromide (also called 2-bromopropane). e) ND = non-detectable.



### 12Table2A. Summary ofworkers' breath concentrations ofn-propyl bromideafor plants 1 and 6 combined. 

### Hamilton Sundstrand Rockford, IL 

### National Institute for Occupational Safety andHealth Centers for Disease Control and Prevention IWSB232.12
nPB Breath concentration (ppmt Date Measure (n=l1) Pre-shift Post-Shift Average



### - 0.23 Day 1 Range NDe 0.11- 0.38 AverageC 0.11 (n 

### =5)d 0.17 (n 

### =

## 8t Day 2 Range ND-O.B NO-0.21 Average 0.097 (n

### =

# st n.a.e Day 3 Range ND-O.B n.a.

Table2B. Summary ofworkers' breath concentrations ofn-propyl bromidef for plant 1.
nPB Breath concentration (ppm)g Date Measure (n =7) Pre-shift Post-Shift Average



### - 0.23 Day 1 Range NOn 0.12

- 0.38 Averageh 0.11 (n

### =4) 0.16 (n

### =4) Day 2 Range NO

- 0.13**ND~0.19** Average 0.096 (n

### =2) 1 n.a. Day 3 Range NO-0.13 n.a.



### 13Table

## 2e. Summary ofworkers' breath concentrations ofn-propyl bromide8 for plant6. 

### Hamilton Sundstrand Rockford, IL National Institute for Occupational Safety and Health Centers for Disease Control and Prevention IWSB232.12
nPB Breath concentration (ppml Date Measure (n=4) Pre-shift Post-Shift Average



### - 0.23 Day 1 Range NDc 0.11- 0.33 Average I 0.18



### - Day 2 Range ND-0.12 0.13-0.21 AverageC 0.098 (n = 3)° e n.a. Day 3 Range ND-0.12 n.a.

Footnotes for Tables 2A, 2B, and 2C: a) iPB was not detected in any ofthe breath samples. b) Units are in parts per million by volume; the amount ofbromopropane in 1 million parts ofbreath. c) ND = non-detectable. Only detectable values were used to calculate averages. d) n varies because only detectable values, in lieuofzero or imputed values, were used to calculate averages. e) Not applicable. Only a "before work" breath sample (e.g. 16-hourpost shift) was collected on day 3. f) Average wasn't calculated because nPB was detected in only one breath sample from this collection period.



### 14Table3A. Summary ofworkers' bromine eoneentrations in urine for plants 1 and 6 eombined. 

### Hamilton Sundstrand Rockford, IL National Institute for Occupational Safety and Health Centers for Disease Control and Prevention IWSB232.12
Chemieal Job Day 1, Before Work 8 Ran2e Avera2e Plants 1& 6 1.8 -22 8.8 Bromine (n = 11) (mg/liter)b ControlsC 0.98

- 16 4.0

Chemical Job Day 1, 24-Hr.Coneentrationd Day 2, 24-Hr. Concentration Ran2e Averae;e Ran2e Avera2e Bromine Plants 1& 6 1.9

- 21 7.7 2.8 -15 6.5 (mglliter) (n = II)

Table 3B. Summary ofworkers' bromine concentrations in urine for plant 1.
Chemical Job Day 1, Before Work 8 Rane;e Averae;e
Plant I 1.8 -13 4.8 Bromine (n = 7) (mg/liter)b ControlsC 0.98

- 16 4.0

Chemical Job Day 1, 24-Hr. Coneentrationd Day 2, 24-Hr. Concentration Rane;e Avera2e Rane;e Avera2e
Bromine Plant 1 1.9

- 8.1 4.1 2.8-8.2 4.6 (mg/liter) (n= 7)



### 15Table3C. Summary ofworkers' bromiue concentrations in urine for plant6. 

### Hamilton Sundstrand Rockford, IL 

### National Institute for Occupational Safety and Health Centers forDisease Control and Prevention IWSB232.12 Chemical Job Day 1, Before Work a Ran2e Avera2e Plant 6 8.7-22 16 Bromine (n :=: 4) (mglliterl ControlsC 0.98 -16 4.0

Chemical Job Day 1, 24-Hr. Concentrationd Day 2, 24-Hr. Concentration Rane:e Averae:e Ran2e Averae:e Bromine Plant 6 7.6**~21** 14 4.2 -15 9.7 (mglliter) (n 

### =4)

Footnotes for Tables 3A, 3B, and 3C: a) Sample was collected before ornearthe start ofthe work shift, after the weekend away from work. b) Units are in milligrams ofbromine per liter ofurine. c) Control samples were collected from 2loffice workers unexposed to nPB, not employed by this company. d) 24-Hour concentrations were calculated from 3 combined samples ofall urine specimens collected at work; after work before bedtime; and upon waking.



### 16Table 4A. Summary ofworkers' propyl mercapturic acid concentrations in urine for plants 1 and 

### 6 combined. 

### Hamilton Sundstrand Rockford, IL 

### National Institute for Occupational Safety and Health Centers for Disease Control and Prevention IWSB 232.12 Chemical Job Day 1, Before Work Ran2e Avera2e Plants 1 & 6**ND~499** 85.9 PMN (n = 11) (/lglliter)b ControlsC**NDd~207** 59.7

Chemical Job Day 1, 24-Hr. Concentratione Day 2, 24-Hr. Concentration Ran2e Avera2e Ran2e Avera2e PMA Plants 1 & 6 15.6**~2390** 649 4.99 2510 571**(~~/liter)** (n = 11)

Table 4B. Summary ofworkers' propyl mercapturic acid concentrations in urine for plant 1. Chemical Job Day 1, Before Work Ran2e Avera2e Plant 1 ND-23.4 10.8 PMN (n = 7) (/lglliter)b**NDd~207** ControlsC 59.7

Chemical Job Day 1, 24-Hr. Concentratione Day 2, 24-Hr. Concentration Ran2e Avera2e Ran2e Avera2e PMA Plant 1 15.6

- 883 250 4.99 -755 268**(~~/liter)** (n= 7)



### 17Table 4C. Summary ofworkers' propyl mercapturic acid concentrations in urine for plant 6. 

### Hamilton Sundstrand Rockford, IL National Institute for Occupational Safety and Health Centers for Disease Control and Prevention IWSB 232.12 Chemical Job Dav 1, Before Work Range Average Plant 6 52.6

- 499 217 PMAa (n :=: 4) (/lglliter)b NDd-207 ControlsC 59.7

Chemical Job Day 1, 24-Hr. Concentratione Day 2, 24-Hr. Concentration Range Average Range Average
PMA Plant 6 (/lglliter) (n 

### =4) 607

- 2390 1350 427-2510 1100

Footnotes for Tables 4A, 4B, and 4C: a) PMA = propyl mercapturic acid. b) Units are in micrograms ofpropyl mercapturic acid per literofurine. (One microgram is one thousand times lessthan a milligram.) c) Control samples were collected from 21office workers unexposed to nPB, not employed by this company. d) ND = non-detectable. e) 24-Hour concentrations were calculated from 3 combined samples ofallurine specimens collected at work; after work beforebedtime; and upon waking.



### 18

### AttachmentI Toxicity ofn-propyl bromide and isopropyl bromide

The molecular structure ofbromopropanes is a simple three carbon alkane chain containing a single bromine substitution. There are two bromopropane isomers: n-propyl bromide [(nPB) also called 1-bromopropane; CAS No. 106-94-5] and isopropyl bromide [(iPB) also called 2- bromopropane; CAS No.75-26-3]. Priorto the lastseveral years, nPB was primarily used to manufacture pharmaceuticals, pesticides, and other chemicals typically in well controlledclosed processes. An international agreementbetween a number ofindustrial nations restricts the manufacture and use ofozone depleting substances including some compounds which were widely used throughout general industry: 1,1 ,I-trichloroethane and chlorofluorocarbons (freons®). In an effortto develop alternatives to replace these ozone depleting solvents, nPB products have been marketed, or are being considered, for metal cleaning/degreasing, automotive degreasing, electronics cleaning, precision cleaning (e.g., plastics, optics, and medical equipment), aerosol products, adhesive solvents, paint and coating solvents, textile drycleaning, printing inks, and asphalt blending (EPA, 2003; Dead Sea Bromine, 1999; Petroferm, 2000). Products containing potential carcinogens trichloroethylene and methylene chloride are also candidates for alternative solvents, especially since the OSHA methylene chloride standard imposes more stringent occupational exposure and medical surveillance criteriawith increased compliance costs. Currently, the principal application for nPB, in terms ofquantities used, is for a vapor degreasing and liquid cleaning agent as well as spray adhesive solvent (EPA, 2003). However, the need to find suitable alternative solvents could expand nPB market applications, substantially increasing the quantities manufactured. The first reports ofhealth effects for bromopropanes occurredin 1996 in a Korean electronics plantwhere iPB was used as a cleaning solvent for electronic switches (Kimet aI., 1996; Park et aI., 1997). An epidemiology case study of33 workers revealed that approximately two-thirds were experiencing reproductive disorders affecting both genders (e.g., low sperm concentrations, low motility or deformed sperm in men; and amenorrhea and elevated follicle stimulating hormone in women) (Kim et aI., 1996). Further, seven workers had pancytopenia (e.g., reduced blood cell counts). An exposure-health effect association was obscuredin this study since breathing zone monitoring was notperformed, and the significance ofreported dermal contact and briefshort-term exposure to very high air concentrations is unclear. Ichihara et ai. (1997; 1999) conducted a similar study at a chemical plantmanufacturing iPB in China. Although severe reproductive disorders were not observed, reduced sperm concentrations and motility as well as decreased hemoglobin and hematocrit were suspected by the authors to be relatedto iPB exposure. Subsequentto these occupational investigations, a series ofrat studies were conducted in Japan with iPB to evaluate male reproductive and female reproductive orhematopoietic toxicity. In a review ofthe literature, Takeuchi et ai. (1997) concludedthatiPB impairs: 

### (i) the testes, especially spermatogonia, (ii) ovarian function by disturbing the estrous cycle, damaging primordial follicles and oocytes, (iii) bone marrow causing pancytopenia. Neurologic effects in rats exposed to iPB were also discovered by Yu et ai. (1999; 2001). 19There has been incentive to use nPB in lieu ofiPB because ofthe perception that nPB has lower toxicity. There are several reports inthe published literature regarding epidemiological and toxicological studies ofnPB which are contraryto this supposition. In a 2001 report, Yu .et

### aI. (2001) demonstrated peripheral and possibly central neurotoxicity 

### in rats but did not show reproductive orhematologic .effects. Several additional reports have concludedthat nPB produces dose dependant estrous cycle irregularities (Yamadaet aI., 2003; Takeuchi et

### aI., 2001); spermiation destruction (Takeuchi et ai., 2001; Ichihara et aI., 2000a); reproductive and developmental toxicity (NTP, 2002; 2004; Ichiharaet aI., 2005); increasedliverenzymes (Lee et aI., 2005); and peripheral and central neurotoxicity (Yu et aI., 2001; Ichiharaet aI., 2000b) inrats at similardose levels thatproducedthese effects by iPB. Ichiharaet aI. (2000b) concluded that nPB appeared to be a more potentneurotoxin than iPB. This conclusionis supported by several rat studies which have shown ataxic gait and hyper-excitability ofthe central nervous system, particularly at higher doses (Fuetaet aI., 2000, 2002a, 2002b, 2004; Honma et aI., 2003; Wang et aI.,2003). Garner et aI. (2006) published a metabolism study which investigated the disposition and excretion ofnPB following intravenous, inhalation and dermal administration using mice and rats ofboth genders, metabolic inhibitors, and genetically altered animals. The authors concludedthat metabolism and excretion were independent ofroute ofadministration. Elimination ofnPB was very rapid with ahalflife under one hour, mostly via exhalation. Urinary excretion occurred by two principal mechanisms: dehalogenation by cytochrome P-450 and conjugation with glutathione. Minor metabolites were also observed indicating several other pathways for elimination. Two case studies inthe US have been published which describe decreased peripheral nerve functioning for three foam cushion workers using spray adhesives containing over 50% nPB (lchihara, et aI. 2002) and aworker who performed metal stripping using a degreasing solvent with approximately 95% nPB (Sclar, 1999). Presenting symptoms included numbness, weakness oflowerextremities, staggering, and parasthesia or dysesthesia. The authors concludedthat nPB likely caused the peripheral and central nervous system defects in these workers. NIOSH has conducted Health HazardEvaluations (HHEs) attwo foam cushion fabricators and an aircraft seat cushion manufacturerwhere nPB was used as a spray adhesive solvent (NIOSH, 2003b; 2002a; 2002b). Full-shiftnPB exposures at these plants identified numerous excursions exceeding 100 ppm, one recommended exposure guideline by some solvent distributers. For comparison, the 2003 proposed EPA industrial exposure guideline is 25 ppm, and the ACGIH TLV® published in 2005 is 10 ppm, measured as an eight-hourtime-weighted average (TWA). Atthe aircraft seat cushion plant, full-shift nPB exposures ranged from 60 to 381 ppm, and 67 of 69 measurements exceeded 100 ppm (NIOSH, 2002a). Analysis ofcomplete blood counts obtained from 43 (61%) ofthe aircraft cushion workers did not establish nor exonerate abnormalities associated with nPB exposure. A reproductive health questionnaire was also administeredbutthe results were also inconclusive.

20Toraason et al. (2006) conducted genotoxic studies to assess DNA damage, invitro, andfrom 64 workers employed attwo ofthe above HHE foam fabricating plants NIOSH investigatedusing PB-based adhesives. The authors concludedthat limited evidence existed at these facilities to show exposure to nPB was associated with increasedDNA damage.

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