Health Hazard Evaluation Report 2014-0170-3263 Page 1

Evaluation of Metalworking Fluid Exposure 

and Dermatitis among Rifle Barrel 

Manufacturing Employees

HHE Report No. 2014-0170-3263

December 2016

Loren C. Tapp, MD, MS

Kendra Broadwater, MPH

Charles A. Mueller, MS

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
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Contents

Highlights...............................................i

Abbreviations ..................................... iii

Introduction......................................... 1

Methods ............................................... 3

Results .................................................. 6

Discussion .......................................... 21

Conclusions........................................ 23

Recommendations............................. 24

Appendix A ........................................ 28

Appendix B ........................................ 31

Appendix C ........................................ 33

References.......................................... 36

Acknowledgements........................... 43

The employer is required to post a copy of this report for 30 days at or near the 

workplace(s) of affected employees. The employer must take steps to ensure 

that the posted report is not altered, defaced, or covered by other material.

The cover photo is a close-up image of sorbent tubes, which are used by the HHE 

Program to measure airborne exposures. This photo is an artistic representation that may 

not be related to this Health Hazard Evaluation. Photo by NIOSH.
Health Hazard Evaluation Report 2014-0170-3263 Page i

We evaluated exposure to 

metalworking fluid and dermatitis 

among employees at a gun 

barrel manufacturing facility. One 

metalworking fluid mist level was 

measured at the occupational 

exposure limit. Some production 

employees reported work-related 

asthma-like symptoms. We also 

found that skin exposure to 

metalworking fluid contributed 

to dermatitis. We recommend 

limiting skin and respiratory 

exposure to metalworking fluid 

by improving metalworking 

fluid mist control, changing 

manual handling practices, 

and improving access to 

and consistent use of gloves. 

Additionally, encouraging 

employees to report possible 

work-related symptoms early may 

prevent more serious problems. 

Highlights of this Evaluation

The Health Hazard Evaluation Program received a request from a manager at a rifle barrel 

manufacturing company. The manager was concerned about skin irritation and rashes among 

employees who were exposed to metalworking fluids. We visited the facility in August 2014 

and November 2014.

What We Did

● We observed work practices and personal protective equipment use.

● We reviewed illness and injury logs, workers’ compensation claims, and air 

sampling reports.

● We interviewed 46 employees about 

work and medical concerns and looked at 

employees’ rashes.

● We took personal air samples for metalworking 

fluid mist and endotoxin. We asked sampled 

employees to complete a symptom survey after 

their work shift.

● We asked all employees to complete a 

questionnaire about their work exposures and 

possible work-related symptoms.

What We Found

● Many employees had skin exposure to 

metalworking fluids, including oils and coolant, 

and to rust inhibitor.

● Several current and former primary area 

employees had a history of rash from skin 

exposure to oil.

● Employees with skin exposure to coolant had 

more work-related dermatitis than employees 

without skin exposure to coolant.

● Ten production employees reported workrelated asthma-like symptoms (chest tightness 

or wheeze that improves away from work). 

● Two shipping employees reported work-related asthma-like symptoms. 

● Work-related asthma-like symptoms may be related to exposures to metalworking fluid 

or other contaminants in the facility.

● One metalworking fluid mist level in the air reached the recommended limit during 

our visit.
Page ii Health Hazard Evaluation Report 2014-0170-3263

● The highest metalworking fluid mist levels occurred in the milling and 

chambering departments.

What the Employer Can Do

● Provide drilling employees with additional tools to reduce handling of oil-covered 

metal chips. 

● Provide computer numerical control machining employees with tools they can use to 

dip parts into rust inhibitor.

● Establish a complete metalworking fluid maintenance program and include mist 

collector maintenance.

● Repeat air monitoring yearly and when processes change or production increases. If levels 

are more than half the recommended exposure limit, repeat monitoring every 6 months. 

● Start a medical surveillance program for employees who are exposed to metalworking fluids.

● Train employees on the hazards of metalworking fluids and ways to avoid skin 

exposure when they are hired and repeat training once every year.

● Make gloves more accessible to production employees and enforce their use when there 

is direct contact with metalworking fluid. 

What Employees Can Do

● Use tools and gloves to avoid skin contact with metalworking fluids and rust inhibitor.

● Wash skin with soap and water if metalworking fluid (coolant or oil) or rust inhibitor 

gets on your skin.

● Do not wash your hands with solvent.

● Tell your supervisor if you notice early signs of skin problems or respiratory 

symptoms that you think may be related to work. Taking action early may prevent 

more serious problems.
Health Hazard Evaluation Report 2014-0170-3263 Page iii

Abbreviations

ACGIH® American Conference of Governmental Industrial Hygienists

ANSI American National Standards Institute 

BLS Bureau of Labor Statistics

CFR Code of Federal Regulations

CFU/mL Colony forming units per milliliter

CI Confidence intervals

CNC Computer numerical control

EU/m3 Endotoxin units per cubic meter

ISEA International Safety Equipment Association

mg/m3 Milligrams per cubic meter

MWF Metalworking fluid

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PPE Personal protective equipment

PR Prevalence ratios

REL Recommended exposure limit

TLV® Threshold limit value

TWA Time-weighted average

WEELTM Workplace environmental exposure level
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Health Hazard Evaluation Report 2014-0170-3263 Page 1

Introduction 

The Health Hazard Evaluation Program received a request from managers at a rifle barrel 

manufacturing company. The request concerned skin irritation and rashes among production 

employees who were exposed to metalworking fluids (MWFs). We visited the facility in 

August and November 2014 to assess MWF exposures and learn more about employee 

symptoms and health concerns. We sent letters summarizing our preliminary findings and 

recommendations in August 2014 and November 2014. We provided employees with their 

own exposure results and the employer with summary exposure results in February 2015 and 

November 2016. 

Background

The rifle barrel manufacturing company began operating in 1976 and moved to the current 

100,000-square-foot-building in 1995. The building was divided into two production areas on 

the first floor and administrative offices on the second floor. At the time of our visits, 

86 nonunion employees worked across two 10-hour shifts Monday through Thursday. 

In 2012, higher demand for the product led the company to hire more employees (up to 

200) and institute two 10-hour work shifts per day. Since then, the number of employees 

has fluctuated between 80 and 200 depending on production demands. Between 2013 and 

2014, three informal, confidential complaints were made to the Occupational Safety and 

Health Administration (OSHA) about lack of access to personal protective equipment (PPE), 

skin and breathing problems, and exposure to MWF. OSHA did not inspect the facility, but 

requested by letter that the company investigate, make needed corrections, and document its 

findings and modifications in writing. At the suggestion of OSHA, the company requested a 

National Institute for Occupational Safety and Health (NIOSH) health hazard evaluation. 

Metalworking Fluids 

This facility mainly used two types of MWFs, a mineral oil-based MWF they refer to as 

“oil” and a semisynthetic water-based MWF they refer to as “coolant,” wording we have 

maintained in this report. Inhalation of MWF aerosols may irritate the throat, nose, and 

lungs and has been associated with chronic respiratory problems. Skin contact with MWF 

may cause skin disorders. Detailed information on occupational exposure limits (OELs) and 

health effects from MWF exposure is presented in Appendix A.

Process Description

The two production areas were separated by a concrete wall with a large center passageway 

for moving materials from one side to the other. The front production area contained the 

shipping department that had large bay doors for receiving raw materials (stainless steel 

and steel alloy cylinders) and shipping finished rifle barrels. The sawing, and secondary 

production processes (chambering, milling, and stamping departments) were located adjacent 

to the shipping department. The back production area contained the primary production 

processes (drilling, reaming, and rifling departments), the clean and inspect stations, the 
Page 2 Health Hazard Evaluation Report 2014-0170-3263

ovens, and the lathe department (a secondary production process). Rifle barrels were 

inspected at each step. The barrels were heated at prescribed times during manufacturing to 

relieve stress and increase strength. Most employees worked in only one department. 

Sawing

After receipt, stock metal bars were cut to length according to the design specifications for 

the rifle barrel order. Stock metal bars came in a variety of steel alloys and stainless steel 

alloys. Semisynthetic water-based MWF (“coolant”) was used during stock metal sawing 

(cutting). Two or three employees worked in sawing.

Primary Production: Drilling, Reaming, and Rifling

Cut metal bars were sent to primary production to machine and finish the inside of the rifle 

barrel. The machines used Garia® 2600 M-12, a 30%–60% mineral oil-based MWF (“oil”) 

to reduce heat, lubricate, and remove metal chips during drilling. The company started using 

this oil in September 2013; previously, the company used Met Drill 744 cutting oil. During 

drilling, the oil was applied to the site of action through the end of the drill bit at about 1,000 

pounds per square inch. The stock bar rotated several thousand times a minute while the 

hole was drilled. The oil was filtered and recycled at each machine reservoir. Drilling caused 

the temperature of the lubricating oil to increase. Using a heat exchange system, the heat 

from the lubricating oil was either exhausted out of the building or used to heat the building, 

depending on the season. The drill created a bore slightly smaller than the diameter required 

in the order specifications. Ten employees worked in drilling. The reaming machines ensured 

that the appropriate bore diameter was reached and was uniform for the length of the barrel. 

The reaming machines also put a finer finish on the interiors of the barrels. The reaming bits 

rotated at a slower rate than during drilling, fewer than 500 rotations per minute. Oil was also 

used during this step but was applied at a lower pressure. Four employees worked in reaming.

In the rifling department, spiral grooves or “rifling” were added to the inside of the rifle 

barrel. Garia 2600 M-12 was used during cut rifling, and QualiChem Company Met-form 

581, another type of straight oil, was used in the button rifling machines. Met-form 581 

contains 60%–80% alkanes and 20%–40% naphthenic petroleum distillates, which are 

both components of mineral oil. Other ingredients together may comprise up to 10% of the 

mixture, but each of these individually is less than 1% of the total mixture. Usually two 

employees worked in rifling.

Clean and Inspect, Heat Treatment

In each department, the supervisor inspected completed barrels. When barrels reached the 

final stage, they underwent a final inspection and cleaning. Employees cleaned barrels by 

dipping batches of them consecutively in three large drums of naphtha solvent. Barrels 

underwent heat treatment in ovens in the back production area. Barrels were placed in ovens 

in batches, where the temperature was gradually increased to 1,100 degrees Fahrenheit. Four 

to six employees cleaned, inspected, dipped, or heat treated rifle barrels. 
Health Hazard Evaluation Report 2014-0170-3263 Page 3

Secondary Production: Lathing, Milling, and Chambering

Secondary production processes machined and finished the outside of the barrel using 

computer numerical control (CNC) machines in the lathe and milling departments. Coolant 

was used to cool, lubricate, and remove chips in these two departments. Seven employees 

worked in lathe and five in milling. CNC chambering machines created threads and 

ammunition housing or “chambers” in the rifle barrels. Of the thirteen CNC chambering 

machines, nine used Garia 2600 M-12 oil as a MWF; the other four machines used coolant. 

Six employees worked in the chambering department. Most CNC-machined parts were 

dipped in Cimcool® Cimguard 10® corrosion inhibitor. 

Methods

The objectives of our evaluation were to: 

1. Assess employee health problems related to MWF exposure.

2. Assess workplace exposures to MWFs, endotoxin, and other workplace hazards.

3. Provide recommendations to reduce exposures and prevent work-related health problems.

In August 2014, we met with employer and employee representatives to discuss the health 

hazard evaluation request and learn more about their concerns. During the initial visit, we held 

confidential medical interviews; reviewed reports, records, and health and safety programs; 

observed employees doing their jobs; and looked at the ventilation system. We returned in 

November 2014 to collect air and bulk MWF samples, observe work practices and PPE use, 

administer a health questionnaire to employees, and collect post-shift symptom surveys. 

First Site Visit

Observations

We observed work processes, practices, and conditions in the manufacturing and shipping 

areas. We noted what kinds of PPE were used, consistency of use, and how effective PPE 

was in preventing dermal exposure to MWF. We looked at the building ventilation and heat 

exchange system. We measured the temperature of MWF in reservoirs using a noncontact 

laser infrared thermometer at the beginning and end of the workday. 

Document Review

We reviewed the following documents:

● Two consultants’ reports concerning exposure to airborne MWF and microbes in bulk MWF 

● OSHA complaint files from 2013–2014 

● Company safety and health, hazard communication, and oil exposure and hygiene 

programs, including training materials 

● Mist collector model information and maintenance information 
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● Safety data sheets 

● OSHA Form 300 Logs of Work-Related Injuries and Illnesses from 2011 through 2014.

Nonfatal Injury and Illness Rates

We used data from the company’s OSHA Logs and data from the Bureau of Labor Statistics 

(BLS) to calculate and compare incidence rates of nonfatal injury and illness between this 

facility and the U.S. small arms manufacturing industry as a whole (North American Industry 

Classification System [NAICS] Code 332994) for years 2011 and 2012. BLS does not 

provide data for NAICS 332994 for years 2013 and 2014, so we compared this facility’s rates 

to NAICS 332990, all other U.S. fabricated metal product manufacturing, for years 2013 and 

2014 [BLS 2016]. 

The incidence rates are for nonfatal injuries and illnesses per 100 full-time employees for 

each year. These rates are useful for comparing incidence to similar industries and tracking 

progress in preventing work-related injuries and illnesses. Incidence rates were calculated 

using the following formula [BLS 2016]:

Incidence rate = number of injuries and illnesses × 200,000 hours / employee hours 

worked annually 

The “200,000 hours” in the formula represents the equivalent of 100 employees working 

40 hours a week, 50 weeks a year. For the number of “employee hours worked annually,” we 

used the number of annual work hours reported by the company on its OSHA 300A forms 

for each year from 2011–2014. These calculations and explanations can be found on the BLS 

website at http://data.bls.gov/iirc/.

Medical Interviews and Medical Record Review

We confidentially interviewed 46 of 47 production employees who worked with MWFs and 

were working on the dates of our visit. We asked about their medical and work history using 

a semi-structured interview form. We reviewed medical records of interviewed employees 

with health problems that might be work-related. We also reviewed medical records related to 

workers’ compensation claims submitted from 2010 through 2014.

Second Site Visit

Observations

We observed work practices and conditions in the manufacturing departments. We noted 

changes in work practices and PPE use since our first visit. 

Sampling for Metalworking Fluid and Endotoxin 

We collected personal air samples for thoracic-sized particles and endotoxin in the production, 

quality control, engineering, and shipping departments. Endotoxin is a compound released from 

certain bacteria when they die or multiply and is believed to cause respiratory illness. Health 

effects and exposure limits related to endotoxin exposure are discussed in Appendix A. 
Health Hazard Evaluation Report 2014-0170-3263 Page 5

We collected 25 personal air samples for thoracic-sized particles and MWF mist and 

7 personal air samples for endotoxin on the first day of the site visit. We collected 19 personal 

air samples for thoracic-sized particles and MWF mist and 2 personal air samples for 

endotoxin on the second day of the site visit. All personal samples were full shift (ranging 

7 hours 11 minutes to 10 hours) except one partial shift sample for endotoxin on a shipping 

employee (2 hours 17 minutes). Thoracic-sized particles have an aerodynamic diameter of 

30 micrometers or less and can reach deeper parts of the lungs than larger particles. We 

collected 8 bulk MWF samples for endotoxin analysis. 

The personal thoracic-sized particle air samples were collected and analyzed by gravimetric 

analysis per NIOSH Method 5524 [NIOSH 2016]. After the filter was gravimetrically 

weighed, a ternary solvent blend was used to extract the MWF fraction from each sample. 

Endotoxin personal air samples were collected using an endotoxin-free three-piece 

37-millimeter closed-face cassette, preloaded with 0.45-micrometer-pore-size polycarbonate 

filters at 2 liters per minute. We collected bulk MWF samples using a sterile pipette to fill 

a 4-ounce sterile bottle. These samples were kept on ice and shipped within 1 day to the 

laboratory for analysis. Samples were analyzed for endotoxin content with the kineticchromogenic procedure using the limulus amebocyte lysate assay [Cambrex 2005]. For these 

analyses, one endotoxin unit (EU) was equivalent to 0.053 nanograms of endotoxin. The 

limit of detection was 0.50 EU per sample.

Questionnaires

We asked all 80 employees at the facility to complete a written questionnaire; 79 participated. 

The questionnaire included questions from the European Community Respiratory Health 

Survey [Grassi et al. 2003] and questions modified from the Nordic Occupational Skin 

Questionnaire [Susitaival et al. 2003]. The questionnaire asked about demographic 

information, work and medical history, PPE use, hygiene habits, and personal exposures. We 

also asked about skin, nasal, and respiratory symptoms in the month prior and in the 

12 months prior to the questionnaire, and whether these symptoms changed on days away 

from work. Self-reported symptoms that improved on days away from work could indicate 

work relatedness and were defined as work-related symptoms.

We created a combination variable, which we called “asthma-like symptoms.” This definition 

may include people who have not been diagnosed as having asthma [Grassi et al. 2003]. 

Asthma-like symptoms were defined as any of the following: 

● current use of asthma medicine 

● wheezing or whistling in the chest in the past 12 months 

● awakening with a feeling of chest tightness in the past 12 months 

● an attack of asthma in the past 12 months

We created another variable called “work-related asthma-like symptoms.” Work-related 

asthma-like symptoms were defined as any of the asthma-like symptoms that improved away 

from work. For each of the bulleted items above, we asked if the symptom had improved 

away from work. Work-related asthma-like symptoms were defined as having one or more of 
Page 6 Health Hazard Evaluation Report 2014-0170-3263

the following:

● Less use of asthma medicine when away from work 

● Wheezing or whistling in the chest in the past 12 months that improves away from work 

● Awakening with a feeling of chest tightness in the past 12 months that improves away 

from work 

● Attacks of asthma in the past 12 months that are less frequent away from work 

We analyzed the data using SAS statistical software version 9.3 to evaluate relationships 

between exposures (oil and coolant) and symptoms (respiratory and skin). When looking 

at skin symptoms, we put employees into exposure groups on the basis of responses to 

questions about handling oil, coolant, or parts wet with oil or coolant. When looking at 

respiratory symptoms, we put employees into exposure groups based on job title as a 

surrogate for airborne oil and coolant exposures. We calculated prevalence ratios (PR) and 

P values using Fisher’s exact test or chi-square test to determine the statistical significance 

of the relationships between MWF exposure groups and symptom prevalence. We also 

calculated 95% confidence intervals (CI). The prevalence ratio is the prevalence of the 

symptom in the exposed group divided by the prevalence of the symptom in the comparison 

group. Statistical significance was set at P < 0.05. When there were sufficient data, we 

evaluated confounding and effect modification factors by stratified analyses. In addition, 

we evaluated the relationship between frequency of MWF skin exposure and work-related 

dermatitis prevalence using the Cochran-Armitage trend test.

Comparing Post-shift Symptom Surveys and Sampling Results 

We administered post-shift symptom surveys over 2 consecutive days to production 

employees who participated in personal air sampling. The surveys asked about pre-shift and 

post-shift skin, eye, and respiratory symptoms that employees may have experienced on the 

days of our evaluation. We defined new-onset symptoms as those present at the end of the 

shift but not present before the shift. We reported the frequency of each new-onset symptom 

for all completed surveys. We also looked at the relationship between airborne MWF levels 

and post-shift symptom occurrence. For new-onset symptoms reported by five or more 

employees, we used a linear mixed model to determine if there was an association between 

personal air MWF concentrations and the reported new-onset symptom. 

Results

First Site Visit

Observations

Work Practices and Equipment Design

We observed that work practices and equipment design contributed to dermal exposure to 

oil and coolant on employees’ hands, arms, legs, and feet. During reaming, oil streaming out 

the barrel being reamed was not well contained by the machine and frequently splashed onto 
Health Hazard Evaluation Report 2014-0170-3263 Page 7

the reaming operator. Some employees, particularly those working in reaming, wore long 

chemical-resistant aprons to protect their clothing against oil contamination. However, we 

observed oil dripping onto employees’ lower pant legs below the aprons. Drilling, reaming, 

and rifling department employees manually handled oil-contaminated parts and removed 

chips from collection basins frequently throughout their shift (Figure 1). The company 

supplied machine operators with tools to scrape scrap metal chips into a pile before manually 

removing the scrap metal chips from drilling machines. Some employees used these tools, 

while others opted to use their gloved hands to gather chips from the machines. Additionally, 

most surfaces, including tools, machinery, and storage baskets in primary production areas 

(drilling, reaming, rifling) were covered in oil and not cleaned regularly. Incidental contact 

between most surfaces and bare skin would lead to contamination. 

We observed that oil splashed or spilled onto the primary production floor throughout the 

workday, creating a slippery walking surface. In some cases, work practices, such as moving 

parts in and out of the machine, transporting parts via baskets, or scooping oil-covered metal 

chips from machines into bins, contributed to oil spills on the floor. Otherwise, oil splashed 

out of some of the machines onto the ground or onto employee aprons, eventually dripping to 

the ground. The main walkways were cleaned twice a day with a commercial floor cleaner to 

reduce the amount of oil on the floor surface and to reduce the risk of slips and falls. During 

our visit, we noted that the floor remained slick despite frequent cleaning and created a slip 

hazard in the drilling, reaming, and rifling departments and the walkways between them. 

Figure 1. Employee with bare forearms removing metal chips from a drilling machine using his gloved hands.

Personal Protective Equipment

Employees were required to wear closed-toed, impact-resistant shoes and safety glasses. 

We observed some employees wearing short-sleeved shirts, sleeveless shirts, and short 

pants while working in production areas. The company provided gloves, but employees 

were not required to wear them. We observed all but one of the drilling, reaming, and rifling 

employees wearing gloves. 
Page 8 Health Hazard Evaluation Report 2014-0170-3263

Employees generally wore one of two types of nitrile gloves when handling parts wet with 

MWF: a 0.015-inch thick (15 mil) cotton-lined green nitrile glove with a gauntlet cuff for oil 

exposure or a thinner black nitrile glove for coolant exposure. Per American National Standards 

Institute/ International Safety Equipment Association (ANSI/ISEA) standard 105-2011, the 

thick green nitrile gloves offer high protection against abrasion (rated 4 on a scale of 5), low 

protection against puncture (rated 1 on a scale of 5) and minimal cut protection against a blade 

(rated 0 on a scale of 5) [ANSI/ISEA 2011]. Employees could get gloves from a vendingstyle machine using their employee numbers. They could also get gloves from department 

supervisors or the tool crib manager. We observed an employee handling oil and parts covered 

in oil not wearing gloves and other employees handling parts wearing torn gloves. We observed 

employees emptying oil and metal chips from inside their gloves. 

Some employees did not wear gloves while removing parts from the rust inhibitor product 

(Cimguard 10). We observed employees fully submersing both hands without gloves in 

Cimguard 10. 

During some tasks, especially in the drilling department, we observed that oil and metal 

chips entered the glove at the cuff. Employees removed the metal chips by taking the gloves 

off and shaking them out. While this may remove larger metal chips, small chips and oil can 

remain inside the gloves and cut and contaminate employees’ hands when they put the gloves 

back on. Most employees folded down the cuffs of the gauntlet-style thicker nitrile green 

gloves to make the gloves easier to remove and to prevent oil from running down the cuff of 

the gloves onto their arms when they raised their hands up. However, this practice also left 

the upper forearm exposed to oil. We saw some employees with oil on their forearms. We 

also observed that employees did not always wash oil off of their arms when they washed 

their hands.

The company provided employees with personal work uniforms to prevent soiling their street 

clothing. A contract uniform company delivered and laundered the uniforms every week. 

However, new employees were not given work uniforms until they had worked 90 days with 

the company. Employees received a work locker where they could keep their uniforms, street 

clothes, and personal effects. 

Oil reservoir temperatures increased from the beginning of the shift to the end of the 

shift. The drilling and rifling department oil reservoirs warmed more than those in other 

departments. We found that the temperature of the MWFs varied between departments and 

within departments. The temperature reached 130° Fahrenheit when operating under 

normal conditions in the drilling department. During our August 2014 site visit, we noted 

that one rifling machine was fitted with a 5-gallon bucket as an oil reservoir while the other 

machines had reservoirs of 15 gallons or larger. The temperature of the 5-gallon reservoir 

reached 140° Fahrenheit, about 45° Fahrenheit hotter than the larger reservoirs in the same 

department. Employees reported that the temperature of the oil in this rifling machine made 

handling the parts uncomfortably hot compared to working on other rifling machines. Prior 

to our second visit, the bucket was replaced with a larger reservoir, effectively reducing oil 

temperature. Maintaining MWF temperatures as low as feasible by using 15-gallon or larger 

reservoirs will ensure that parts are not excessively hot for handling. 
Health Hazard Evaluation Report 2014-0170-3263 Page 9

Ventilation

Supply air was provided to the production facility by large fans attached to fabric ducts 

whose length and diameter were adjusted using ropes. The fans brought 50,000 cubic feet 

per minute of outdoor air into the building, which was designed to be positively pressurized. 

During cold weather, the outdoor air was heated by a heat exchanging unit that conditioned 

incoming air using heat diverted from the oil reservoirs. When the heat exchanger was 

not used to heat incoming air, the heated air was exhausted out of the building from the 

heat exchanger. During our visit, several stationary pedestal fans operated in the drilling 

department to cool employees. They were positioned to draw air from the drilling area and 

blow the air toward duct openings in the exterior wall that housed non-operational fans, 

which have not worked for several years, including during our visit. Large articulated bay 

doors were opened to the outdoors in the secondary area during our evaluation. These doors 

are reportedly only kept closed during cold weather. Radiant heaters above the drilling 

department were used during winter. Employees noted that when the heaters were first turned 

on, typically on the first very cold day of fall or winter, the oil and dust accumulation burned 

off and filled the facility with thick smoke.

Metalworking Fluid Maintenance 

According to managers, the oil in the drilling, reaming, and rifling machines was not changed 

regularly. MWF was changed only when it was obviously contaminated or developed an 

odor. The company had no written MWF maintenance plan. Additional oil was added to the 

reservoir as needed. Metal particles were removed from the MWF with custom bag filtration 

and magnets. The pH of the coolant used in the CNC machines was checked regularly and 

maintained within an operational range of 8.5 to 9.5 by adding coolant. CNC machines in the 

chambering department that used the Garia 2600 M-12 were equipped with mist collectors, 

which collected MWF mist and reduced ambient levels of MWF in the air. 

Document Review

In 2012 and 2013, the company’s insurance provider took eight full-shift personal samples 

for total MWF in air. The total MWF exposures ranged from 0.05 to 0.50 milligrams per 

cubic meter (mg/m3). One full-shift personal exposure measurement was equal to the NIOSH 

REL for total MWF mist of 0.50 mg/m3. This employee worked as a CNC machine operator, 

but the department was unspecified. Four personal measurements exceeded half of the 

NIOSH REL, or 0.25 mg/m3; these measurements were taken in the CNC (n = 2), 

reaming (n = 1), and drilling (n = 1) locations.

OSHA received three employee complaints in 2013 and 2014. The complaints were about 

skin and breathing exposure to MWF, improper maintenance of MWF, and lack of access 

to PPE. OSHA noted that several cases of dermatitis occurred after the Met-Drill 744 was 

replaced with the Garia 2600 M-12. As part of its response to OSHA in October 2013, the 

company provided sampling results from October 2008. In October 2008, the company took 

five full-shift personal air samples. Three drilling employees had total MWF exposures of 

0.53, 0.61, and 0.68 mg/m3. Total MWF exposures for two employees in the CNC areas were 

0.63 and 0.40 mg/m3. Four of the five measurements exceeded the NIOSH REL of 0.5 mg/m3
Page 10 Health Hazard Evaluation Report 2014-0170-3263

for total MWF particulate.

According to February 2013 sample results for bacteria provided to us by the company, one 

coolant sample contained 105 colony forming units per milliliter (CFU/mL). According to 

the coolant manufacturing company, the coolant system had been designed to be colonized 

by specific nonpathogenic bacteria [Blaser Swisslube Inc. 2013]. The Health and Safety 

Executive in the United Kingdom states that well-maintained MWFs should have bacterial 

concentrations below 103 CFU/mL of fluid [HSE 2006]. Concentrations between 103 and 106

CFU/mL indicate reasonable control, and concentrations greater than 106 CFU/mL indicate 

poor control [HSE 2006]. 

We reviewed product information about the mist collectors used on CNC machines in the 

chambering department. The company had installed MistBusters® on CNC machines that 

use Garia 2600 M-12, which are all located in the chambering area. They had installed eight 

MistBuster Model 500 mist collectors and three MistBuster Model 850 mist collectors. Mist 

collectors are not used on CNC machines running the water-based coolant. The company 

does not perform scheduled maintenance on the mist collectors. The maintenance department 

stocks replacement elements. We learned from management that when a mist collector’s 

performance declines and mist becomes visible in the air, the element is cleaned or replaced. 

The maintenance department does not keep records of when they are serviced or which 

elements are replaced. The manufacturer recommends periodic maintenance that includes 

cleaning the mist impingers and the electronic cell when they contain “excessive buildup.” 

The manufacturer notes in the MistBuster manual that the frequency of maintenance depends 

on the operation and machines collecting water-based machining fluid will need to be cleaned 

more frequently than those collecting petroleum-based fluid [Air Quality Engineering 2016]. 

Occupational Safety and Health Administration Injury and Illness Log Review

We reviewed the company’s OSHA 300 and 300A Logs from 2011 through 2014. Table 1 

shows the number of employees, hours worked, and OSHA 300 Log entries during those years. 
Health Hazard Evaluation Report 2014-0170-3263 Page 11

Table 1. Numbers of hours worked, employees, and injury and illness entries reported on 

OSHA Logs from 2011 through 2014

2011 2012 2013 2014

Total # employees 119 171 225 110

Total # hours worked 73,313 311,486 368,412 237,076

Total # of entries 11 36 39 27

Skin entries 2 7 7 3

Respiratory entries 0 0 0 2

Musculoskeletal sprains or strains 3 16 20 9

Lacerations, punctures, contusions, 

abrasions

3 9 8 10

Slips and falls 0 0 1 3

Musculoskeletal disorders 

(cumulative trauma)

0 0 2 0

Other entries 3 4 1 0

Musculoskeletal sprains/strains and lacerations/punctures/contusions/abrasions accounted for 

most entries for each year. Drilling operators accounted for 12 of the 19 skin entries over the 

4 years. Primary machine operators other than drilling operators accounted for 5 skin entries 

(one reaming, one rifling, and three employees not designated to one primary machining 

type); one material handler and one saw operator accounted for the remaining two entries. 

One drilling operator and one CNC deburr operator accounted for the two respiratory entries. 

Comparing Nonfatal Injury and Illness Rates to the U.S. Small Arms 

Manufacturing Industry 

Figure 2 compares the rates of workplace injuries and illnesses per 100 full-time workers 

between the facility and U.S. small arms manufacturing industry for years 2011 and 2012, 

and between the facility and all other fabricated metal product manufacturing for years 2013 

and 2014, on the basis of company OSHA Logs and BLS data. This facility’s rates were four 

to six times higher than the U.S. industry rates from 2011–2014. 
Page 12 Health Hazard Evaluation Report 2014-0170-3263

Figure 2. Comparing rates of workplace injuries and illnesses per 100 full-time workers between the 

facility and U.S. small arms manufacturing industry (NAICS 332994), years 2011−2012, and U.S. all 

other fabricated metal product manufacturing (NAICS 332990), years 2013–2014 [BLS 2016].

Medical Interviews

We confidentially interviewed 46 of the 47 production employees: 17 worked with CNC 

machines, 19 worked or inspected in drilling, reaming, or rifling (primary department), and 

10 worked in other jobs including maintenance, saws, material handling, assembly/deburr, 

floating, stamping, and ovens. Among the 46 interviewed employees, 42 (91%) were male, 

the mean age was 42 years (range: 21–65 years), and the mean time worked at the facility 

was 5 years (range: 10 months–19 years). 

Seventeen of the 46 employees reported having symptoms in the past year that they felt were 

work-related. Of these 17 employees, 11 described having a rash in the past year, 3 reported 

respiratory symptoms (1 with flu-like illness, 1 with chest heaviness at work, and 1 with 

dry cough at work), 2 reported nasal symptoms at work, and 1 reported a shoulder injury. 

Of the 11 employees reporting rash in the year prior to our site visit, all reported working 

in drilling, reaming, or rifling when their rash began and 8 reported that they thought the oil 

at work caused the rash. Of these 11 employees, 3 had a rash at the time of our interviews. 

On examination, red papules, pustules, and inflamed hair follicles were present on these 

employees’ wrists and/or forearms, areas that were not covered by protective gloves. The 

skin examinations and employees’ medical and work history provide evidence that many of 

these 11 employees’ rashes were likely related to oil exposure at work. Two employees’ skin 

lesions looked consistent with oil folliculitis (Figure 3). Of the three employees reporting 

work-related respiratory symptoms, two worked in CNC milling and one in maintenance.
Health Hazard Evaluation Report 2014-0170-3263 Page 13

Figure 3. Two inflamed, reddened hair follicles (folliculitis) on forearm of employee working in 

primary production. 

Additionally, during the interviews, some employees reported that gloves, especially the 

black nitrile gloves, were not easily accessible and they felt they were discouraged from 

asking for additional gloves during the work shift. Therefore, they would continue to wear 

their gloves when torn or contaminated inside. Some employees reported purchasing their 

own thin nitrile gloves to use at work.

Medical Record and Workers’ Compensation Claims Review

We reviewed medical records from two interviewed employees and two former employees 

who reported experiencing skin or respiratory illness between 2010 and 2014, possibly 

related to work exposures. The two former employees had histories and physical 

examinations that were consistent with work-related contact dermatitis. These employees 

worked in primary production. A third employee, a CNC machinist, had a rash that was not 

work-related and respiratory symptoms that might have been related to work exposures. 

However, there was not enough information in the medical record to determine workrelatedness of the respiratory symptoms. A fourth employee, working as an inspector 

in primary production, was diagnosed with chronic obstructive pulmonary disease with 

bronchospasm that could have a work-related component.

We also reviewed medical records from thirteen (one current and twelve former) employees 

seen for workers’ compensation claim examinations from 2010 through 2014 related to skin 

or respiratory illness. Of these thirteen employees, eleven were seen for rash only, one was 

seen for rash and respiratory symptoms (two different claims), and one employee was seen 

for respiratory symptoms. Of the twelve claims for rash, ten were determined to be related 

to oil exposure from work (eight occurred prior to September 2013 when the company 

changed the oil in the primary department), one was from a reaction to ingredients in gloves 

worn at work, and one was not work-related. Of the two respiratory claims, one was found 
Page 14 Health Hazard Evaluation Report 2014-0170-3263

to be related to particulate exposure at work, and the second was determined to be possibly 

aggravated by work but more likely from cardiopulmonary disease.

Second Site Visit

Observations and Workplace Changes

During our August 2014 site visit, we noted that oil splashes were common in the reaming 

department, regularly contaminating employees’ clothing, especially pants below protective 

aprons on reaming operators. By November 2014, the employer had provided guards that 

employees placed on reaming machines manually after setting up the parts. The guards 

worked well in preventing oil from splashing out of the machines (Figure 4). 

Figure 4. Using the handle, a metal guard is placed over the site on the reaming machine where oil is 

streaming from the end of metal cylinders. Prior to using this guard, oil splashed from the end of the 

metal cylinders onto employees.

Between our first and second site visits, the employer trained all production employees on 

preventing MWF contamination of the skin, and the importance of frequent and thorough 

skin washing. The training also included information about the effects of MWF exposure 

on skin, including folliculitis. During informal conversations on our November 2014 site 

visit, some employees reported washing their hands, forearms, and face more frequently than 

before the training. 
Health Hazard Evaluation Report 2014-0170-3263 Page 15

Metalworking Fluid and Endotoxin Exposures

Overall, personal thoracic particulate mass exposures ranged from 0.056–0.40 mg/m3. 

Summary exposure results are shown in Table 2. The highest geometric mean exposures 

occurred in the chambering department where exposures ranged from 0.23–0.40 mg/m3 and 

averaged 0.33 mg/m3 of thoracic particulate mass. The highest individual personal 

exposures occurred in the chambering department (0.40 mg/m3) and milling department 

(0.39 mg/m3). We compared the air sample results for thoracic-sized particulate to the NIOSH 

REL. The NIOSH REL does not differentiate between oil-based and water-based MWFs. Of 

the 43 personal air samples for thoracic particulate over these two shifts, one was at 

the NIOSH REL of 0.40 mg/m3, the lowest OEL for MWF particulate. Additionally, 15 of the 

43 personal air thoracic particulate samples were over 0.2 mg/m3, which is half of the NIOSH 

REL. These employees worked in chambering, quality control inspection, lathe, milling, 

maintenance, drilling, and reaming. In the production areas, extracted MWF mass comprised 

80% of total thoracic particulate mass, on average. Individual exposure measurements for 

thoracic particulate mass and extracted MWF mass can be found in Table B1 in Appendix B. 

Table 2. Personal air sampling results for thoracic particulate mass in November 2014

Job/Activity # of 

samples

Sample duration range 

(min)

Geometric mean and (range) 

concentration

(mg/m3)

Drilling operator 7 449–625 0.18 (0.13–0.21)

Reaming operator 5 574–636 0.18 (0.13–0.21)

Rifling operator 4 524–631 0.15 (0.12–0.19)

Lathe operator 3 360–577 0.23 (0.19–0.30)

Milling operator 5 606–621 0.26 (0.15–0.39)

Chambering operator 4 590–607 0.33 (0.23–0.40)

Quality control inspector 5 516–613 0.17 (0.12–0.27)

Engineer 2 478–525 0.07 (0.056–0.08)

Maintenance 2 542–577 0.21 (0.18–0.24)

Hand grinder 1 624 0.21

Oven operator 2 613–614 0.14 (0.12–0.16)

Saws 1 321 0.12

NIOSH REL 0.4

Full shift exposures to endotoxin in air ranged from 12–58 endotoxin units per cubic meter of 

air (EU/m3) (Table B2 in Appendix B). One partial shift (2 hours 17 minutes) exposure was 

70 EU/m3. The geometric mean exposure was 24 EU/m3 across nine personal samples. We 

compared the air sample results for endotoxin to the OEL set by the Dutch Expert Committee 

on Occupational Safety. There are no OELs for endotoxin in the United States. All 

samples were below the recommended OEL of 90 EU/m3. The highest endotoxin exposure 

measurement occurred in the shipping department (70 EU/m3). This was only a partial 

shift exposure measurement, lasting just over two hours because the employee declined to 

continue sampling after the lunch break.
Page 16 Health Hazard Evaluation Report 2014-0170-3263

Across the eight bulk MWF samples, endotoxin concentrations ranged from 3.36–598 

EU/mL. There are no exposure limits for endotoxin in bulk MWF. However, the 

concentrations of endotoxin were not high compared with levels reported in the scientific 

literature. Simpson and associates found endotoxin ranging from the limit of detection 

to 1,870,000 EU/mL in 154 water-based MWF samples; the median was 8,039 EU/mL 

[Simpson et al. 2003]. In a study of three facilities, Cyprowski et al. [2007] found that the 

average concentration of bacterial endotoxin in the used MWFs was 773 EU/mL. Endotoxin 

concentrations ranged from 220 to 1,700 EU/mL in a manufacturing facility for steel roller 

bearings [NIOSH 2006].

Questionnaires

Of the 79 employees who completed a health questionnaire, 68 (86%) were male. The mean 

age was 43 years (range: 21–65 years), and the median amount of time worked at the facility 

was 3 years (range: 1 month–28 years). 

The 79 participating employees reported working the most time in the following jobs during 

the year prior to the questionnaire: 25 in primary manufacturing (including sawing, drilling, 

reaming, rifling, and quality control), 25 in secondary manufacturing (including CNC 

lathes, milling, and chambering, and quality control), 18 in other jobs on the manufacturing 

floor (including machine shop/maintenance, material handler, shipping, clean and inspect, 

stamping, assembly, and supervisory personnel), and 11 in administrative or clerical jobs. 

Of the 79 employees, 70 (89%) reported handling oil, coolant, or parts wet with oil or coolant 

the week of the survey. Among these 70 employees, 47 (67%) reported wearing gloves when 

handling these substances that week (20 always, 13 usually, and 14 sometimes). Of the 

70 employees, 23 (33%) reported that they did not wear gloves the week of the survey when 

handling oil or coolant, or parts wet with these fluids.

We asked about PPE use during the year prior to the questionnaire. Among the 68 employees 

who were not administrative or clerical staff, 20 (29%) reported that they always wore 

gloves, 13 (19%) usually, 19 (28%) sometimes, and 16 (24%) never. Among employees 

who reported wearing gloves, they reported that they changed their gloves once per shift 

on average (range: 0 to 8 times per shift). However, three employees reported changing 

their gloves only when torn. One employee reported wearing a respirator sometimes while 

performing work duties, three reported wearing protective sleeves (1 usually, 2 sometimes), 

and 8 reported wearing aprons (4 always, 1 usually, and 3 sometimes).

The 79 employees reported washing their hands with soap and water 2 to 16 times per shift, 

with one employee reporting 50 times per shift. Without this employee, the mean was seven 

times per shift. Seven employees reported using solvents to wash their hands at work, seventeen 

reported using skin moisturizer at work, and eight reported using barrier creams at work. 

Among the 79 participating employees, 23 (29%) reported dermatitis on some part of their 

body during the 12 months prior to the questionnaire. Of these 23 employees, 14 reported 

dermatitis on the wrists or forearms during the prior 12 months, 11 on the hands or fingers, 

7 on the face or neck, 5 on the legs or ankles, and 3 on the back or abdomen; 
Health Hazard Evaluation Report 2014-0170-3263 Page 17

12 reported dermatitis on more than one body area. Among these 23 employees, 12 reported 

symptoms that were work-related based on our definition. All 12 employees with workrelated dermatitis reported skin exposure to coolant during the 12-month period; 9 of the 

12 also reported skin exposure to oil. No work-related dermatitis was reported among the 

16 employees with skin exposure to oil only. Five employees reported having dermatitis on 

the day of the survey.

To evaluate the relationships between work-related dermatitis and skin contact with oil 

or coolant, we asked about these exposures during the previous 12 months. Fifty-seven 

employees reported skin exposure to oil, and 50 reported skin exposure to coolant. Among 

these employees, 36 reported exposure to both oil and coolant. Only 8 employees reported 

no oil or coolant exposure to skin (Table 3). Work-related dermatitis was reported only by 

employees who reported skin exposure to coolant (either coolant alone or coolant and oil).

Table 3. Reported skin exposure to MWFs during past 12 months 

Reported skin exposure 

(n = 78*)

Number of employees with 

work-related dermatitis†

% of employees with 

work-related dermatitis

Both oil and coolant (n = 36) 9 of 34 26

Only coolant (n = 13) 3 of 10 30

Only oil (n = 21) 0 of 16 0

Neither oil or coolant (n = 8) 0 of 8 0

*One employee who reported skin exposure to coolant did not provide data on skin exposure to oil.

†Ten employees did not provide data to assess work-related dermatitis.

Table 4 shows results of the analysis of the association between skin exposures and workrelated dermatitis. We found no statistically significant association between skin exposure 

to oil and work-related dermatitis (PR = 1.08, 95% CI [0.34, 5.38], P = 0.99). However, we 

found a statistically significant increase in work-related dermatitis among employees with 

skin exposure to coolant (27%, including those with coolant alone plus those with coolant 

and oil) compared to employees without this exposure (0%) (PR = undefined, 95% CI [1.58, 

undefined], P < 0.01). We looked at other factors individually to see whether they changed 

the relationship between skin exposure to oil or coolant and the prevalence of work-related 

dermatitis, but we found no meaningful changes. These factors included age, sex, smoking 

status, atopy, glove use, washing hands with solvent, lotion use, barrier cream use, and 

participating in hobbies with chemical or substance exposures that could affect skin. One 

difficulty in evaluating the effect of glove use, lotion use, and barrier cream use on dermatitis 

is that we had no information on whether the employee started using these items before or 

after developing dermatitis.
Page 18 Health Hazard Evaluation Report 2014-0170-3263

Table 4. Prevalence of work-related dermatitis during past 12 months 

Exposure Yes or No No. 

employees

No. reporting workrelated dermatitis (%)Prevalence ratio 

(P value) [95% CI]

Skin exposure to oil Yes

No

50

18

9 (18)

3 (17)

1.08 (0.99)

[0.34, 5.38]

Skin exposure to 

coolant

Yes

No

45

24

12 (27)

0

Undefined* (0.01)

[1.58, undefined]

*Denominator of the ratio of prevalences is 0.

In addition, we found no cases of work-related dermatitis among those reporting no coolant 

exposure, five cases (25%) among those exposed to coolant a few times a week or few 

times a month, and seven cases (32%) among those with daily exposure to coolant. In other 

words, as the frequency of skin exposure to coolant increased, the prevalence of work-related 

dermatitis significantly increased (P < 0.01). 

To evaluate the relationship between MWF exposure and respiratory symptoms, we asked 

participants which job they spent the most time in during the past 12 months. We classified 

the predominant air exposure (coolant or oil) for each job title on the basis of information and 

observations from our first site visit. We classified employees working in drilling, reaming, 

rifling, “clean and inspect,” or “primary group leader” jobs as having predominantly air 

exposure to oil (n = 22), those working with CNC lathe, CNC milling, or sawing jobs as 

having predominantly air exposure to coolant (n = 17), those working in CNC chambering, 

CNC set up, machine shop/maintenance, material handling, or a job working both saws 

and primary machines as having air exposure to both oil and coolant (n = 20), and the other 

employees (administrative/clerical employees, engineers, shipping, stamping, assembly, or 

dipping employees) as having minimal air exposure to oil or coolant (n = 19). It is possible 

for some employees, such as the 19 with minimal air exposure to oil or coolant, to have skin 

exposure to oil or coolant if they handle parts wet with oil or coolant. We could not classify 

one employee’s job into one of these four categories so did not include him/her in this 

analysis. Table 5 shows the number and percent of employees reporting respiratory illness or 

work-related respiratory symptoms in each group. 
Health Hazard Evaluation Report 2014-0170-3263 Page 19

Table 5. Employee reports of work-related nasal symptoms, work-related respiratory symptoms, 

and respiratory illness in the past 12 months, by type of MWF exposure in air (N = 78)

Symptom Employees in 

jobs with 

predominantly 

coolant 

exposure

(n = 17)

No. (%)

Employees in 

jobs with 

predominantly 

oil exposure

(n = 22)

No. (%)

Employees in 

jobs with both 

coolant and oil 

exposure 

(n = 20)

No. (%)

Employees in 

jobs with 

minimal coolant 

and oil 

exposure 

(n = 19)

No. (%)

Statistical 

measure: 

P value*

Work-related 

nasal 

symptoms†

4 (24) 7 (32) 6 (30) 2 (11) 0.38

Work-related 

wheeze

1 (6) 4 (18) 3 (15) 2 (11) 0.77

Work-related 

chest tightness

0 1 (5) 0 2 (11) 0.39

Work-related 

asthma attack

0 0 0 1 (5) 0.46

Work-related 

use of asthma 

medication

0 0 0 0 1

Asthma-like 

symptoms‡

3 (18) 5 (23) 9 (45) 2 (11) 0.09

Work-related 

asthma-like 

symptoms§

1 (6) 4 (18) 3 (15) 2 (11) 0.77

Pneumonia or 

flu 

2 (12) 2 (9) 0 5 (26) 0.07

*P value compares the difference in the percent of symptoms for the four groups. A P value < 0.05 

is considered statistically significant.

†Work-related symptoms were defined as symptoms that improved away from work.

‡Asthma‐like symptoms were defined as any of the following: current use of asthma medicine, 

wheezing or whistling in the chest in the past 12 months, awakening with a feeling of chest 

tightness in the past 12 months, or attack of asthma in the past 12 months.

§Work-related asthma-like symptoms were defined as having one or more of the following: less 

use of asthma medicine when away from work, wheezing or whistling in the chest in the past 

12 months that improves away from work, awakening with a feeling of chest tightness in the past 

12 months that improves away from work, or attacks of asthma in the past 12 months that are less 

frequent away from work. Employees reporting work-related asthma-like symptoms are a subset of 

those reporting asthma-like symptoms.

When we looked at employee groups based on the categories in Table 5, we found that the 

work-related nasal and respiratory symptom percentages were not significantly different 

between the groups. Work-related nasal symptoms were reported more than other workrelated respiratory symptoms. Employees reporting work-related asthma-like symptoms are 

included among the employees reporting asthma-like symptoms. Two employees reporting 

work-related asthma-like symptoms also reported having flu or pneumonia during the 

same year. It is possible that the asthma-like symptoms were related to having a respiratory 

infection, although we would not expect the symptoms to improve away from work. 
Page 20 Health Hazard Evaluation Report 2014-0170-3263

When we looked at only production employees (n = 65), we found 10 (14%) employees 

reporting work-related asthma-like symptoms (by our definition) and 19 (29%) reporting 

work-related nasal symptoms. Production employees included those with jobs predominantly 

on the production floor: sawing, drilling, reaming, rifling, CNC lathe, CNC milling, 

CNC chambering, CNC set up, machine shop/maintenance, material handling, clean and 

inspect, dipping, stamping, assembly, shipping, primary group lead and QC team lead. Non 

production employees included administrative, clerical, engineering, and administrative 

assistant (n = 13).

Post-shift Health Survey

Over our 2-day evaluation, 30 employees completed 48 post-shift surveys, 29 on the first day 

and 19 on the second day. Eighteen employees participated both days, eleven participated the 

first day only, and one participated the second day only. Eight of the 30 employees reported 

one or more new-onset symptoms; all eight reported new-onset runny nose. Runny nose was 

the most common new-onset symptom employees reported (n = 10) (Table 6). 

Table 6. Results of post-shift symptom surveys over 2 days (n = 48 surveys)

Symptom Number of times 

symptom was 

reported at 

end of shift

Number of times 

symptom was 

reported at 

start of shift*

Number of times 

symptom was reported 

at end, but not start, 

of work shift

Runny nose 15 5 10

Nasal congestion 6 4 2

Persistent cough 6 4 2

Shortness of breath 2 1 1

Chest tightness 2 1 1

Wheezing 3 2 1

Irritated eyes 3 2 1

Skin redness on 

hands, wrists, or arms

2 0 1

*If post-shift symptom was not present, we did not ask about pre-shift symptom.

Comparing Post-shift Symptom Survey Results with Metalworking Fluid 

Sampling Results

We looked at new-onset symptoms during the work shift in relation to MWF concentration in 

air during the same shift. We were able to analyze only the relationship between new-onset 

runny nose and MWF concentration; the numbers were too small for this analysis for the 

other new-onset symptoms. We did not find a relationship between new-onset runny nose and 

concentrations of MWF in air. 
Health Hazard Evaluation Report 2014-0170-3263 Page 21

Discussion

Results from our initial evaluation (August 2014) found skin exposure to oil as the likely cause 

of work-related dermatitis among employees. However, on the basis of our questionnaire 

findings from our second site visit (November 2014), employee reports of skin contact with 

coolant, but not oil, were significantly associated with work-related dermatitis. The difference 

in findings between our first and second site visits is likely due to a variety of factors: 

1. Preventive measures were introduced after our first site visit. Splash guards were 

installed on reaming machines to prevent oil splashes and we saw an increased use 

of tools to remove oil-coated chips in the primary department, rather than manual 

removal techniques. 

2. Employee training was held after our first site visit, which led to improvements in 

employee skin hygiene and work practices, and increased use of PPE. This training 

may have been emphasized to primary employees since the primary area was the one 

with the most skin problems at the time.

3. Different methods of data collection were used. During our first site visit, two NIOSH 

investigators interviewed employees using a semi-structured interview form with openended questions. During the second visit, self-administered questionnaires were completed 

by the employees. The questionnaire asked more in-depth questions about symptoms. 

4. Recall bias may have occurred. During the first site visit, employees reporting 

dermatitis the year prior to the interview may have forgotten about their bout of 

dermatitis at the time of the second site visit. 

5. A modest decrease in production occurred between our first and second site visits, so fewer 

employees made fewer parts, resulting in reduced dermal and respiratory exposures.

6. An increase in production during 2012 and 2013 may have led to higher exposures 

during this time period, particularly in the primary area where machines are not 

enclosed and do not have mist collectors. Additionally, newly hired employees may 

have had less experience in avoiding oil exposure to their skin (through proper work 

practices and consistent PPE use) and removing oil from their skin regularly through 

frequent and thorough hand hygiene. The OSHA Logs and workers’ compensation 

claim records included several employees who no longer worked at the company 

during our visits. 

7. In the fall of 2013, the plant changed to a new type of oil-based MWF. Since dermatitis 

can sometimes take months to resolve, employees who may have developed a rash from 

the old oil would have responded yes when asked about rash in the year prior to August 

2014. The new oil may have led to a reduction in dermatitis among primary department 

employees which was observed in our second site visit (November 2014). 

Employees working on CNC machines also had skin exposure to the corrosion inhibitor, 

Cimguard 10. We did not ask about exposure to the anticorrosion product on our 

questionnaire, so we do not know if exposure to this corrosion inhibitor, to the coolant, or 

to both, led to dermatitis. However, we observed that nearly all employees who worked 
Page 22 Health Hazard Evaluation Report 2014-0170-3263

on CNC machines manually dipped their machined parts into the Cimguard 10, and some 

employees did not wear gloves when performing this work task. According to the safety data 

sheet, Cimguard 10 can cause defatting, drying, and irritation of the skin. The manufacturer 

recommends that employees wear nitrile gloves when handling this product to prevent 

skin problems. We also found, based on our observations and questionnaire data, that most 

employees with skin exposure to oil, coolant, or both, did not wear gloves or protective 

sleeves adequately to protect their skin. Skin contact with MWF may cause allergic contact 

dermatitis, irritant contact dermatitis, or oil folliculitis (irritation or infection of hair follicles) 

depending on the chemical composition, additives and contaminants, type of metal being 

machined, and the exposed individual’s tendency for developing allergies [Chew and 

Maibach 2003; Slodownik et al. 2008; WISHA 2001]. Limiting skin exposure is critical to 

preventing allergic and irritant disorders and folliculitis related to MWF exposure. Studies 

have shown that about one in four employees diagnosed with occupational contact dermatitis 

will have persistent symptoms despite treatment or job change [Cretkovski et al. 2006; 

Jungbauer et al. 2004]. Additional information about contact dermatitis and tips to reduce or 

prevent work-related contact dermatitis are given in Appendix C.

Although the HHE request did not include concerns about respiratory symptoms, our 

experience at other plants using MWFs has shown that employees with MWF exposure 

generally report both skin and respiratory symptoms. This plant was no different. Work-related 

nasal, respiratory, and asthma-like symptoms were reported by production employees in this 

plant and were likely related to coolant and/or oil exposures. This, paired with measurements 

showing historical and current MWF concentrations that meet or exceed the NIOSH REL, 

indicate additional measures are needed to reduce airborne exposures on the production floor to 

prevent these work-related symptoms. Appendix A includes additional information about MWF 

health effects. Our findings are consistent with other studies which show nasal symptoms are 

commonly reported among MWF-exposed employees [Park et al. 2008]. 

One MWF mist level we measured was at the NIOSH REL and some MWF mist levels were 

above half of the REL. NIOSH recommends more frequent air sampling when MWF air 

exposures are more than half the REL. The highest levels were found in the CNC chambering 

and milling departments. We measured several MWF air levels close to half of the REL in the 

primary area during our visit. The company sampling records indicated that MWF exposure 

levels varied during 2008–2014. The causes of these variations are difficult to pinpoint, but 

are likely related to changes in exposure controls in the workplace and variations in control 

performance, work practices, hygiene, and production levels. The NIOSH REL is intended 

to prevent or greatly reduce respiratory disorders associated with MWF exposure. Limiting 

exposure to MWF aerosols is also prudent because previous exposures to some MWF have 

been associated with increased risk of some types of cancer. Although actions taken by the 

manufacturing industry in the last several decades have reduced that risk, it is not known if 

these actions have eliminated the risk [NIOSH 2013].

We know that employees can develop respiratory symptoms when exposed to MWF levels 

below the NIOSH OELs [NIOSH 1998]. One study found significantly more upper and lower 

respiratory symptoms among employees exposed to a mean value of total MWF aerosols 

of 0.4 mg/m3, which is below the NIOSH REL for total MWF aerosols of 0.5 mg/m3, 
Health Hazard Evaluation Report 2014-0170-3263 Page 23

compared to unexposed employees [Lillienberg et al. 2010]. Park et al. studied an auto parts 

manufacturing employee population; 61% of MWF-exposed employees reported rhinitisrelated symptoms. Air sampling found that 82% of employees at this facility were exposed 

to total MWF levels at or below 0.5 mg/m3 [Park et al. 2008]. Looking at the general 

population, Guerra et al. found rhinitis (defined as runny or stuffy nose or episodes of 

sneezing apart from a cold) to be a significant risk factor for adult-onset asthma in those with 

and without history of allergies [Guerra et al. 2002]. The majority of production employees 

who reported respiratory symptoms at your facility were exposed to MWF air levels 

below the REL. Overall, the best way to prevent upper and lower respiratory symptoms 

and diseases among MWF-exposed employees is to keep MWF levels as low as feasible. 

Additionally, employees exposed to MWF would benefit from medical monitoring and any 

employee reporting asthma-like symptoms needs to be medically evaluated.

Shipping employees, who we considered minimally exposed to airborne MWF, reported 

work-related respiratory symptoms. We cannot determine the cause(s) of these symptoms 

with certainty, based on the exposures we evaluated. A partial-shift endotoxin exposure 

measurement for one shipping employee was high; although the sampled exposure for this 

employee may not reflect full shift exposure, endotoxin exposure may be contributing to 

respiratory symptoms among employees in this work area. Endotoxin has been found in 

agricultural dusts (cotton, grain, potato, peanut processing plants; animal barns and compost 

bins), in contaminated water systems (metalworking fluids; paper, nylon, and fiberglass 

manufacturing plants), office and home dust (likely from pools of water in heating and 

ventilation systems), and cigarette smoke [Reed and Milton 2001]. In your facility, coolant 

is a likely source of endotoxin exposure, with the endotoxin settling onto surfaces over time. 

Exposure to endotoxin has been shown to cause respiratory symptoms [DECOS 2010; Reed 

and Milton 2001]. Additional information on endotoxin exposure limits and health effects are 

discussed in Appendix A. Other possible exposures in the shipping department may include 

gasoline and diesel vehicle exhaust when trucks deliver raw materials to the shipping bay or 

when finished materials are trucked away from the facility. Since this evaluation focused on 

the evaluation of metalworking fluid exposures, finding work-related respiratory symptoms 

among shipping employees was unexpected since they were not directly involved in 

production. When work-related symptoms are newly identified, jobs in which employees are 

experiencing symptoms should be evaluated for exposures and work characteristics that may 

be contributing factors.

The higher rates of illnesses and injuries in this facility compared to the U.S. small arms 

manufacturing industry identifies a need to further improve prevention measures. The 

majority of injury and illness entries were marked as musculoskeletal strains and sprains.

Conclusions

Reduced production levels and changes made in the plant in 2013–2014 —including 

switching to a different oil and improving exposure controls, training, work practices, and 

hygiene— have reduced the risk of dermatitis from oil-based MWFs. However, we found 

a significant association between skin exposure to coolant and work-related dermatitis. 

Co-exposure to the corrosion inhibitor may have been an important contributing factor. 
Page 24 Health Hazard Evaluation Report 2014-0170-3263

Employees with work-related respiratory symptoms were exposed to airborne MWF levels 

that have been known to cause or exacerbate respiratory symptoms, although the exposures 

are at or below NIOSH-recommended limits. Actions are needed to protect employees from 

developing or exacerbating dermal and respiratory problems related to MWF and other 

chemical exposures in the plant.

Recommendations

On the basis of our findings, we recommend the actions listed below. We encourage the rifle 

barrel manufacturing company to use a labor-management health and safety committee or 

working group to discuss our recommendations and develop an action plan. Those involved 

in the work can best set priorities and assess the feasibility of our recommendations for the 

specific situation at the facility. 

Our recommendations are based on an approach known as the hierarchy of controls. This 

approach groups actions by their likely effectiveness in reducing or removing hazards. In 

most cases, the preferred approach is to eliminate hazardous materials or processes and install 

engineering controls to reduce exposure or shield employees. Until such controls are in place, 

or if they are not effective or feasible, administrative measures and PPE may be needed. 

Engineering Controls

Engineering controls reduce employees’ exposures by removing the hazard from the process or by 

placing a barrier between the hazard and the employee. Engineering controls protect employees 

effectively without placing primary responsibility of implementation on the employee. 

1. Change the chip removal procedures in the drilling department to reduce dermal 

MWF exposure. This may include providing small shovels, dust pans, or vacuums and 

discouraging employees from pulling chips from the machine or collection bins by hand. 

2. Provide baskets or other tools for employees to use when dipping parts into the 

corrosion inhibitor (Cimguard 10). Until baskets can be provided, require employees 

to use nitrile gloves when manually dipping parts into the Cimguard 10. The glove 

cuff should be long enough to prevent dermal exposure to both MWF and Cimguard 

10 while working. 

3. Provide all employees with high friction mats at their work stations to prevent slips 

and falls in locations where regular cleaning is not sufficient.

Administrative Controls

The term administrative controls refers to employer-dictated work practices and policies 

to reduce or prevent hazardous exposures. Their effectiveness depends on employer 

commitment and employee acceptance. Regular monitoring and reinforcement are necessary 

to ensure that policies and procedures are followed consistently.

1. Establish a comprehensive preventive MWF maintenance program, as specified 

in Chapter 9 of the NIOSH document, “Criteria for a Recommended Standard: 
Health Hazard Evaluation Report 2014-0170-3263 Page 25

Occupational Exposure to Metalworking Fluids” [NIOSH 1998]. This includes cleaning 

machines thoroughly before adding clean MWF and cleaning and maintaining mist 

collectors regularly. If the maintenance program does not consistently reduce airborne 

MWF exposure below half the NIOSH REL, install additional mist collectors on 

chambering and milling CNC machines and replace lower capacity mist collectors with 

higher capacity mist collectors. Do not rely on poor performance and visible MWF 

mist in the production floor air to determine when mist impingers and electronic cells 

in the mist collector should be cleaned. The mist collectors used at the site can also be 

installed on CNC machines that use coolant. More information about the function and 

maintenance of MWF mist collectors can be found in OSHA’s “Metalworking Fluids: 

Safety and Health Best Practices Manual” at the following website: 

https://www.osha.gov/SLTC/metalworkingfluids/metalworkingfluids_manual.html.

2. Consult with the MWF manufacturers to identify best practices for MWF maintenance, 

including change-out and cleaning schedules. If not properly maintained, the recycling 

reservoirs in CNC machines can harbor undesirable and unexpected bacteria. Proper 

maintenance is particularly important to maintain coolant quality. The manufacturer of 

the coolant used at this facility recommends cleaning coolant systems and replacing 

used coolant annually [Blaser Swisslube Inc. 2013].

3. Encourage drilling, reaming, and rifling employees to use work practices and tools 

to prevent oil from spilling onto to the floors and walkways when removing metal 

chips, transferring parts to and from the machines, and transporting parts between 

departments. Ensure that normal equipment operation doesn’t cause oil to splash onto 

the floor or onto aprons. 

4. Implement an exposure monitoring program for MWF in air. All employees exposed to 

MWF should be included in the air monitoring program. Perform exposure monitoring 

annually in each department where MWF is used and at least every 6 months in 

departments where exposures have exceeded one half of the NIOSH REL. The NIOSH 

MWF RELs are 0.40 mg/m3 for thoracic particulate and 0.5 mg/m3 for total particulate. 

Notify workers of all sampling results and monitor exposed workers more frequently 

until at least two consecutive samples indicate that exposures no longer exceed the 

REL. Additionally, perform personal MWF air monitoring when significant process 

changes have been made or production levels have changed. 

5. Start a medical monitoring program for employees who are exposed to MWFs. 

Periodic use of a medical questionnaire that focuses on skin and respiratory symptoms 

may be helpful. The questionnaire should be given prior to placement in a job with 

MWF exposure and periodically thereafter. Questionnaire responses can help identify 

work areas and tasks that need additional evaluation and employees who need 

additional medical follow-up. A medical monitoring program helps prevent, identify, 

and manage skin and respiratory disease among included employees. It includes 

preplacement or initial examination, periodic examination, detailed examination for a 

subset of employees, physician’s reports, and follow-up evaluations. More information 

about medical monitoring and its implementation can be found in the NIOSH 

document “What You Need to Know About Occupational Exposure to Metalworking 
Page 26 Health Hazard Evaluation Report 2014-0170-3263

Fluids” at https://www.cdc.gov/niosh/docs/98-116/pdfs/98-116.pdf.

6. Assess respiratory hazards in the departments where shipping employees work. 

Identify and evaluate respiratory exposures, existing ventilation, and workplace 

practices that may be contributing to work-related asthma-like symptoms among 

shipping department employees. 

7. Prohibit employees from using solvents to clean their skin. Provide non-irritating 

cleaning agents and soaps at wash stations for employees to use.

8. Encourage employees to report all potential work-related skin or respiratory problems 

to their supervisors. Employees with persistent symptoms should be evaluated by 

an occupational medicine physician or a medical provider specializing in workplace 

illnesses. The Association of Occupational and Environmental Clinics has an online 

directory of such providers at http://www.aoec.org/directory.htm. Employees with 

definite or possible occupational skin or respiratory diseases should be protected from 

exposures to substances that cause or exacerbate the disease. In some cases of allergic 

contact dermatitis, allergic occupational asthma, and hypersensitivity pneumonitis, 

employees may have to be reassigned with retention of pay and employment status to 

areas where exposure is minimal or nonexistent.

9. Encourage employees to discuss their work exposures with their primary healthcare 

provider and to share any exposure sampling records and any health concerns with 

him or her.

10.Train all employees who will be handling MWF on the proper handling and use of 

MWF and on the hazards and potential health effects associated with MWF exposure 

upon entering the workforce and annually thereafter. Include information on how 

to avoid skin irritation, such as by washing their arms up to the elbows whenever 

they wash their hands at work. Also include information on how to carefully select 

moisturizers, soaps, and skin cleaners because some components such as lanolin and 

fragrances are known allergens and may cause allergic contact dermatitis in sensitive 

individuals. Guidelines for MWF training are included in the NIOSH document “What 

You Need to Know about Occupational Exposure to Metalworking Fluids” at https://

www.cdc.gov/niosh/docs/98-116/pdfs/98-116.pdf. 

11.When considering a change in MWFs, corrosion inhibitors, or other products used 

in production, consider the potential impact on employee respiratory and dermal 

health. As part of managing health risks of product changes, consult with the product 

manufacturers about reported health risks, perform exposure monitoring to carefully 

monitor the impact of the change of product on exposures, and closely monitor 

changes in employee-reported health effects. As part of a comprehensive health and 

safety program, all new processes, process changes, or product changes should be 

evaluated for new exposures or changes in exposures. 

12.Clean surfaces in the plant periodically to reduce and prevent dust and other 

particulate buildup. Wet wiping or using a vacuum with a high efficiency particulate 

air (HEPA) air filter would be appropriate; avoid dry sweeping because it can cause 

settled materials to be kicked up into the air. 
Health Hazard Evaluation Report 2014-0170-3263 Page 27

13.Monitor injury and illness logs routinely to identify particular job duties, work 

materials, machines, or areas of the plant that may be associated with high numbers 

of workplace injuries and illnesses. Focus on these areas for preventive actions. For 

example, OSHA has guidelines for preventing musculoskeletal strains and sprains. 

They can be found at https://www.osha.gov/SLTC/ergonomics/controlhazards.html. 

14.Do not turn on the radiant overhead heaters for the first time in the cold season when 

employees are present. Before a forecast of cold weather, turn on the radiant heaters 

when the building is unoccupied to prevent smoke exposure to employees. 

Personal Protective Equipment

PPE is the least effective means for controlling hazardous exposures. Proper use of 

PPE requires a comprehensive program and a high level of employee involvement and 

commitment. The right PPE must be chosen for each hazard. Supporting programs such as 

training, change-out schedules, and medical assessment may be needed. PPE should not 

be the sole method for controlling hazardous exposures. Rather, PPE should be used until 

effective engineering and administrative controls are in place.

1. Provide new employees with non-personalized work uniforms for temporary use until 

they reach the employment benchmark of 90 days, at which time they could receive 

the personalized uniforms.

2. Improve access to gloves so employees can change their gloves when needed. For 

example, have gloves available in each work area. Production employees should have 

a new pair of disposable gloves every shift and change gloves when they are damaged 

and at lunch breaks. Educate employees that reusing gloves increases the risk of 

contaminating the inside of the gloves, which would result in dermal MWF exposure 

and possible skin problems.

3. Try multiple styles of longer cuffed gloves that are easier to remove without rolling 

down the cuff. Ensure that chosen gloves are of the appropriate material and thickness 

to prevent cuts during metal chip handling. Involving employees in the selection 

process will help ensure that the selected gloves will be used properly. 

4. Require CNC machining employees to use gloves to protect their hands from the 

corrosion inhibitor (Cimguard 10) until dipping baskets or dipping tools are available.
Page 28 Health Hazard Evaluation Report 2014-0170-3263

Appendix A: Occupational Exposure Limits and 

Health Effects

NIOSH investigators refer to mandatory (legally enforceable) and recommended OELs for 

chemical, physical, and biological agents when evaluating workplace hazards. OELs have 

been developed by federal agencies and safety and health organizations to prevent adverse 

health effects from workplace exposures. Generally, OELs suggest levels of exposure that 

most employees may be exposed to for up to 10 hours per day, 40 hours per week, for a 

working lifetime, without experiencing adverse health effects. However, not all employees 

will be protected if their exposures are maintained below these levels. Some may have 

adverse health effects because of individual susceptibility, a pre-existing medical condition, 

or a hypersensitivity (allergy). In addition, some hazardous substances act in combination 

with other exposures, with the general environment, or with medications or personal habits of 

the employee to produce adverse health effects. Most OELs address airborne exposures, but 

some substances can be absorbed directly through the skin and mucous membranes.

Most OELs are expressed as a time-weighted average (TWA) exposure. A TWA refers to 

the average exposure during a normal 8- to 10-hour workday. Some chemical substances 

and physical agents have recommended short-term exposure limits ceiling values. Unless 

otherwise noted, the short-term exposure limit is a 15-minute TWA exposure. It should not be 

exceeded at any time during a workday. The ceiling limit should not be exceeded at any time.

In the United States, OELs have been established by federal agencies, professional 

organizations, state and local governments, and other entities. Some OELs are legally 

enforceable limits; others are recommendations. 

● The U.S. Department of Labor OSHA permissible exposure limits (29 CFR 1910 

[general industry]; 29 CFR 1926 [construction industry]; and 29 CFR 1917 [maritime 

industry]) are legal limits. These limits are enforceable in workplaces covered under the 

Occupational Safety and Health Act of 1970. 

● NIOSH RELs are recommendations based on a critical review of the scientific and 

technical information and the adequacy of methods to identify and control the hazard. 

NIOSH RELs are published in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 

2010]. NIOSH also recommends risk management practices (e.g., engineering controls, 

safe work practices, employee education/training, PPE, and exposure and medical 

monitoring) to minimize the risk of exposure and adverse health effects.

● Other OELs commonly used and cited in the United States include the threshold limit 

value (TLVs), which are recommended by American Conference of Governmental 

Industrial Hygienists (ACGIH), a professional organization, and the workplace 

environmental exposure levels (WEELs), which are recommended by the American 

Industrial Hygiene Association, another professional organization. The TLVs and 

WEELs are developed by committee members of these associations from a review of 

the published, peer-reviewed literature. These OELs are not consensus standards. TLVs 

are considered voluntary exposure guidelines for use by industrial hygienists and others 
Health Hazard Evaluation Report 2014-0170-3263 Page 29

trained in this discipline “to assist in the control of health hazards” [ACGIH 2016]. 

WEELs have been established for some chemicals “when no other legal or authoritative 

limits exist” [AIHA 2016].

Outside the United States, OELs have been established by various agencies and organizations 

and include legal and recommended limits. The Institut für Arbeitsschutz der Deutschen 

Gesetzlichen Unfallversicherung (Institute for Occupational Safety and Health of the German 

Social Accident Insurance) maintains a database of international OELs from European Union 

member states, Canada (Québec), Japan, Switzerland, and the United States. The database, 

available at http://www.dguv.de/ifa/GESTIS/GESTIS-Internationale-Grenzwerte-fürchemische-Substanzen-limit-values-for-chemical-agents/index-2.jsp, contains international 

limits for more than 2,000 hazardous substances and is updated periodically. 

OSHA requires an employer to furnish employees a place of employment free from 

recognized hazards that cause or are likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970 (Public Law 91–596, sec. 5(a)(1))]. This is 

true in the absence of a specific OEL. It also is important to keep in mind that OELs may not 

reflect current health-based information.

When multiple OELs exist for a substance or agent, NIOSH investigators generally 

encourage employers to use the lowest OEL when making risk assessment and risk 

management decisions. NIOSH investigators also encourage use of the hierarchy of controls 

approach to eliminate or minimize workplace hazards. This includes, in order of preference, 

the use of (1) substitution or elimination of the hazardous agent, (2) engineering controls 

(e.g., local exhaust ventilation, process enclosure, dilution ventilation), (3) administrative 

controls (e.g., limiting time of exposure, employee training, work practice changes, medical 

surveillance), and (4) PPE (e.g., respiratory protection, gloves, eye protection, hearing 

protection). Control banding, a qualitative risk assessment and risk management tool, is a 

complementary approach to protecting employee health. Control banding focuses on how 

broad categories of risk should be managed. Information on control banding is available at 

http://www.cdc.gov/niosh/topics/ctrlbanding/. This approach can be applied in situations 

where OELs have not been established or can be used to supplement existing OELs.

Metalworking Fluids

Metalworking fluids are complex mixtures used to cool, lubricate, and remove metal 

chips from tools and parts during machining of metal stock. Most straight oils are highly 

refined products of petroleum stocks and do not contain water. Other types of MWFs 

(soluble, semisynthetic, and synthetic) are water-based mixtures that may require dilution. 

Metalworking fluids often contain other substances, including biocides, corrosion inhibitors, 

metal fines, tramp oils, and biological contaminants [Burton et al. 2012; NIOSH 1998]. 

MWFs may increase in temperature, depending on the heat created by the process and the 

composition of the MWF. Inhalation of MWF aerosols may irritate the throat, nose, and lungs 

and has been associated with chronic bronchitis, asthma, hypersensitivity pneumonitis, and 

worsening of pre-existing respiratory problems [Burton et al. 2012]. NIOSH recommends 

limiting exposures to MWF aerosols to 0.4 mg/m3 for the thoracic particulate mass, as a 
Page 30 Health Hazard Evaluation Report 2014-0170-3263

TWA concentration, for up to 10 hours per day during a 40-hour workweek. However, some 

workers have developed work-related asthma or hypersensitivity pneumonitis at MWF 

exposures below the NIOSH recommended exposure level, so maintaining MWF levels 

below the REL is best practice [NIOSH 1998]. 

Skin contact with MWF may cause allergic contact dermatitis or irritant contact dermatitis, 

depending on the chemical composition, additives and contaminants, type of metal being 

machined, and the exposed individual’s tendency for developing allergies [WISHA 2001]. 

Synthetic, semisynthetic, and soluble oil MWF are diluted with water, so excess bacteria may 

grow if MWF is not properly monitored and maintained. The Health and Safety Executive in 

the United Kingdom states that well-maintained MWF should have bacterial concentrations 

below 103 CFU/mL of fluid [HSE 2006]. Concentrations between 103 and 106 CFU/mL 

indicate reasonable control, and concentrations greater than 106 CFU/mL indicate poor 

control [HSE 2006]. 

The NIOSH REL is intended to prevent or greatly reduce respiratory disorders associated 

with MWF exposure. In addition, limiting dermal (skin) exposure is critical to preventing 

allergic and irritant disorders related to MWF exposure. NIOSH recommends that all 

employees exposed to MWF at over half the REL receive medical monitoring, and all 

employees with exposure to MWF may benefit from medical monitoring [NIOSH 1998]. 

Supervision of the medical monitoring program should be done by a physician or other health 

professional with expertise in the identification and management of MWF-related respiratory 

conditions and skin diseases. 

Endotoxin

The outer cell walls of Gram-negative bacteria may release lipopolysaccharide compounds 

called endotoxin when the bacteria die or multiply. Endotoxin is believed to cause adverse 

respiratory effects such as chronic bronchitis and asthma. In 2010, the Dutch Expert 

Committee on Occupational Safety recommended a health-based OEL for airborne endotoxin 

of 90 EU/m3 as an 8-hour TWA [DECOS 2010]. No accepted OELs have been developed in 

the United States because of the variability of sampling and analytical methods, and because 

of a lack of data showing a consistent dose-response relationship.
Health Hazard Evaluation Report 2014-0170-3263 Page 31

Appendix B: Detailed Personal Exposure 

Measurements

Table B1. Individual thoracic particulate and extracted MWF full-shift exposure measurements 

Job title Day 1

sample

time

(min)

Day 1

total thoracic

particulate

(mg/m3)

Day 1

extracted

MWF

particulate

(mg/m3)

Day 2

sample

time

(min)

Day 2

total

thoracic

particulate

(mg/m3)

Day 2

extracted

MWF

particulate

(mg/m3)

Chambering CNC 

operator

607 0.37* 0.34 592 0.23* 0.17

Chambering CNC 

operator

603 0.34* 0.30 590 0.40† 0.33

Drilling operator 449 0.17 0.15 — — —

Drilling operator 591 0.21* 0.20 523 0.20* 0.16

Drilling operator 612 0.17 0.10 618 0.13 0.093

Drilling operator 622 0.21* 0.19 625 0.15 0.12

Drilling quality 

control inspector

613 0.27 0.22 — — —

Engineer 478 [0.056] [0.055] 525 [0.077] [0.027]

Hand grinder — — — 624 0.21* 0.17

Lathe operator 420 0.21* 0.16 577 0.19 0.15

Lathe operator 491 0.30* 0.20 — — —

Lathe quality 

control inspector

547 0.17 0.14 516 0.13 0.12

Maintenance 577 0.18 0.090 542 0.25* 0.18

Milling CNC operator 612 0.13 0.10 621 0.39* 0.34

Milling CNC operator 606 0.15 0.11 — — —

Milling CNC operator — — — 610 0.35* 0.15

Milling CNC operator 617 0.25* 0.15 — — —

Oven operator 614 0.16 0.12 613 0.12 0.10

Reaming operator 574 0.19 0.20 — — —

Reaming operator 632 0.20* 0.16 623 0.15 0.11

Reaming operator 636 0.21* 0.19 623 0.13 0.084

Rifling operator 614 0.19 0.16 516 0.12 [0.075]

Rifling operator 611 0.13 0.12 524 0.16 0.12

Rifling operator 616 0.15 0.14 631 0.15 0.13

Rifling quality 

control inspector

600 0.17 0.12 602 0.12 0.12

Saw operator 431 0.12 0.12 — — —

NIOSH Recommended Exposure Limit for total thoracic particulate is 0.4 mg/m3

— The compound was not sampled for on this day

[ ] The concentration was between the minimum detectable concentration and the minimum 

quantifiable concentration and there is more uncertainty associated with this value; the minimal 

quantifiable concentration ranged from 0.074 to 0.11 mg/m3 for extracted MWF fraction and 

0.075 to 0.11 mg/m3 for total thoracic particulate

*The exposure is at least one half of the NIOSH REL

†The exposure meets the NIOSH REL
Page 32 Health Hazard Evaluation Report 2014-0170-3263

Table B2. Individual full-shift endotoxin exposure concentrations

Job title Day 1 

endotoxin 

(EU/m3)

Day 1 

sample time 

(min)

Day 2 

endotoxin 

(EU/m3)

Day 2 

sample time 

(min)

Lathe operator 17 579 — —

Milling CNC operator — — 38 595

Milling CNC operator 58 1 — —

Hand grinder 12 462 — —

Shipping 70* 137 — —

Milling CNC operator 21 500 — —

CNC set up 28 544 — —

Safety 15 577 13 615

— The compound was not sampled for in air on this day

*This sample was partial-shift (2 hours 17 minutes)
Health Hazard Evaluation Report 2014-0170-3263 Page 33

Appendix C: Contact Dermatitis

Contact dermatitis makes up 90% to 95% of all occupational skin diseases [Ingber 

and Merims 2004; Lushniak 2004]. Contact dermatitis, both irritant and allergic, is an 

inflammatory skin condition caused by skin contact with agents such as chemical irritants 

(irritant contact dermatitis) or allergens (allergic contact dermatitis). Irritant contact 

dermatitis is skin inflammation due to direct cell damage from a chemical or physical agent, 

while allergic contact dermatitis is a delayed immune reaction. Over 57,000 chemicals are 

reported to cause skin irritation, but only 3,700 chemicals are known skin allergens [Belsito 

2005]. Usually, only a small percentage of people are susceptible to skin allergens.

In contact dermatitis, the skin initially turns red and can develop bumps and small, oozing 

blisters. After several days, crusts and scales form. Stinging, burning, and itching often occur. 

With no further contact with the agent, the dermatitis usually disappears in 1 to 3 weeks. 

With chronic exposure, deep fissures, scaling, and darkening of the skin can occur. Exposed 

areas of the skin, such as hands and forearms, have the greatest contact with irritants or 

allergens and are most commonly affected. Over 80% of occupational contact dermatitis 

involves the hands [Belsito 2005; Flyvholm et al. 2007; Warshaw et al. 2003]. If the agent 

gets on clothing, it can bring on dermatitis at areas of greatest contact, such as thighs, upper 

back, armpits, and feet. Dusts can produce dermatitis at areas where the dust accumulates 

and is held in contact with the skin, such as under the collar and belt line, at the tops of socks 

or shoes, and in skin creases, such as inside elbows and behind knees. Mists can produce 

dermatitis on the face and neck. Irritants and allergens can be transferred to distant areas of 

the body, such as the trunk or genitalia, by unwashed hands or from areas of accumulation, 

such as under rings or in finger webs. 

It is often impossible to clinically distinguish irritant contact from allergic contact dermatitis, 

as both can have a similar appearance and both can result in an acute, subacute, or chronic 

condition. Irritant contact dermatitis can be caused by many factors. The most common 

skin irritant at work is wet work, defined as exposure of skin to liquid for more than 2 hours 

per day, use of occlusive gloves for more than 2 hours per day, or frequent hand washing 

[Chew and Maibach 2003; Slodownik et al. 2008]. Other common causes of irritant contact 

dermatitis include soaps and detergents, solvents, food products, cleaning agents, plastics and 

resins, petroleum products and lubricants, metals, and machine oils and coolants [Chew and 

Maibach 2003; Slodownik et al. 2008]. Frictional irritant contact dermatitis can be caused by 

low humidity, heat, paper, tools, metals, fabrics, plastics, fibrous glass and other particulate 

dusts, and cardboard, among other causes [McMullen and Gawkrodger 2006; Morris-Jones 

et al. 2002]. Causes of allergic contact dermatitis include plants (e.g., poison ivy), metallic 

salts, germicides, plastic resins, rubber additives, and fragrances [Mathias 1990]. In patients 

with occupational contact dermatitis who were skin-patch tested, the most common relevant 

allergens included thiuram mix, carba mix, bacitracin, methyldibromo glutaronitrile/

phenoxyethanol, formaldehyde, glutaraldehyde, methylmethacrylate, nickel, cobalt, and 

chromium [Warshaw et al. 2007, 2008].

Studies on the prognosis of occupational contact dermatitis stress the importance of primary 

prevention. One study found that 32% of 124 surveyed patients had severe hand dermatitis 
Page 34 Health Hazard Evaluation Report 2014-0170-3263

5 years after they were initially diagnosed with irritant hand dermatitis. Severity was 

measured by self-reported frequency of relapses, frequency of dermatologist visits, and 

use of topical corticosteroids [Jungbauer et al. 2004]. Another study found that 25% 

of 540 surveyed patients had persistently severe or aggravated symptoms 1 year after 

initial diagnosis of occupational hand dermatitis. Poor prognosis was associated with the 

presence of atopic dermatitis and being 25 years of age or older. Prognosis was not affected 

by whether the dermatitis was irritant or allergic. Those with severe occupational hand 

dermatitis at baseline had a higher risk of taking sick leave and job loss in the following year 

than those with mild cases. The study found no significant improvement in the disease after 

the change of job [Cvetkovski et al. 2006]. Widespread hand dermatitis on initial examination 

was found to be the greatest factor for a poor long-term prognosis in a third study [Meding et 

al. 2005]. In addition, many skin disorders, including contact dermatitis, have been shown to 

have a significant impact on quality of life [Cvetkovski et al. 2005; Fowler et al. 2006; Kadyk 

et al. 2003; Lan et al. 2008].

Prevention of Contact Dermatitis

Avoiding irritants and allergens, in addition to wet work, is the first step in dermatitis 

prevention. Liberal use of skin moisturizers helps to prevent contact dermatitis by 

maintaining a healthy skin barrier, and also helps to repair this barrier if it has been 

compromised [Chew and Maibach 2003]. The following list provides strategies in the 

prevention of occupational contact dermatitis:

○ Identifying irritants and allergens

○ Substituting chemicals that are less irritating or allergenic

○ Establishing engineering controls to reduce exposure

○ Emphasizing personal and occupational hygiene

○ Establishing educational programs to increase awareness in the workplace

○ Using PPE, such as gloves and special clothing [NIOSH 1988]

Chemical changes in industrial materials have been beneficial. For example, the addition of 

ferrous sulfate to cement to reduce the hexavalent chromium content has been effective in 

reducing occupational allergic contact dermatitis in Europe [Goh and Gan 1996]. Protective 

gloves can reduce or eliminate skin exposure to hazardous substances if used correctly, but 

may actually cause or worsen hand dermatitis (by permeation and penetration) if selected 

poorly and used improperly (by contamination) [Foo et al. 2006]. The use of PPE may 

occlude irritants or allergens next to the skin, and PPE components may directly irritate 

the skin. Therefore, the correct use of PPE is at least as important as the correct selection 

of materials [Kwon et al. 2006]. Similarly, the excessive pursuit of personal hygiene in 

the workplace may actually lead to misuse of soaps and detergents and cause irritant 

contact dermatitis. Proper hand washing methods and adequate moisturizing are valuable 

in preventing contact dermatitis [Warshaw 2003]. The effectiveness of barrier creams is 

controversial because data on the protective nature of these topical products during actual 

working conditions involving high-risk exposures are limited. Educating the workforce about 
Health Hazard Evaluation Report 2014-0170-3263 Page 35

skin care, exposures, and PPE use is an especially important measure in the prevention of 

occupational contact dermatitis [Loffler et al. 2006; Schwanitz et al. 2003; Weisshaar et al. 

2006]. The following list provides tips on proper hand washing [Warshaw et al. 2003]:

● Avoid hot water; use lukewarm or cool water instead.

● Use mild cleansers without perfume, coloring, or antibacterial agents.

● Pat hands dry, especially between fingers.

● Apply skin moisturizer generously after hand washing and repeat throughout the day.

● Avoid rubbing, scrubbing, the use of washcloths, and the overuse of soap and water.

This additional list provides tips for the workplace [Warshaw et al. 2003]:

● Remove rings before work.

● Wear protective gloves in cold weather and for dusty work.

● Wear tight-fitting leather gloves for frictional exposures.

● When performing wet work, wear cotton gloves under vinyl or other nonlatex gloves.

● Avoid immersing hands; use running water if possible.
Page 36 Health Hazard Evaluation Report 2014-0170-3263

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Keywords: North American Industry Classification System 332994 (Small Arms, Ordnance, 

and Ordnance Accessories Manufacturing), New Hampshire, metalworking fluids, MWFs, 

respiratory, dermatitis, coolant, mineral oil, rifles, guns
Health Hazard Evaluation Report 2014-0170-3263 Page 41

The Health Hazard Evaluation Program investigates possible health hazards in the workplace 

under the authority of the Occupational Safety and Health Act of 1970 (29 U.S.C. § 669(a)

(6)). The Health Hazard Evaluation Program also provides, upon request, technical assistance 

to federal, state, and local agencies to investigate occupational health hazards and to prevent 

occupational disease or injury. Regulations guiding the Program can be found in Title 42, Code 

of Federal Regulations, Part 85; Requests for Health Hazard Evaluations (42 CFR Part 85).

Disclaimer

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by NIOSH.

Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. NIOSH is not responsible for the 

content of these Web sites. All Web addresses referenced in this document were accessible as of 

the publication date.

Acknowledgments

Analytical Support: Bureau Veritas North America

Desktop Publisher: Shawna Watts 

Editor: Ellen Galloway 

Industrial Hygiene Field Assistance: Karl Feldmann, Leonard Zwack

Logistics: Donnie Booher, Kevin Moore

Medical Field Assistance: Sophia Chiu, Kerton Victory

Data Support: Denise Giglio

Availability of Report

Copies of this report have been sent to the employer and employees at the facility. The state and 

local health department and the Occupational Safety and Health Administration Regional Office 

have also received a copy. This report is not copyrighted and may be freely reproduced. 

Recommended citation for this report:

NIOSH [2016]. Evaluation of metalworking fluid exposure and dermatitis among rifle 

barrel manufacturing employees. By Tapp LC, Broadwater K, Mueller CA. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, NIOSH Health 

Hazard Evaluation Report 2014-0170-3263, 

http://www.cdc.gov/niosh/hhe/reports/pdfs/2014-0170-3263.pdf.
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