Health Hazard Evaluation Report 2013-0075-3264 Page 1

Investigation of Dermal and Respiratory 

Exposures to Metalworking Fluids at an 

Automotive Parts Manufacturer

Report No. 2013-0075-3264

December 2016

Joshua M. Harney, MS, CIH

Loren Tapp, MD, MS

U.S. Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Page 2 Health Hazard Evaluation Report 2013-0075-3264

Contents

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

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

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

Methods ............................................... 2

Results .................................................. 4

Discussion .......................................... 17

Conclusions........................................ 20

Recommendations............................. 20

Appendix A ........................................ 23

Appendix B ........................................ 24

Appendix C ........................................ 28

Appendix D ........................................ 37

References.......................................... 40

Acknowledgements........................... 47

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 2013-0075-3264 Page i

We evaluated medical 

concerns and employee 

exposures at an automotive 

part manufacturer. Some 

employees reported 

skin and respiratory 

symptoms related to 

work. The company 

lowered metalworking 

fluid mist levels below the 

recommended exposure 

limit by improving local 

exhaust ventilation and 

adding a splash shield to 

each compressed air gun.

Highlights of this Evaluation

The Health Hazard Evaluation Program received a request from a manager at an automotive 

part manufacturing plant. The request concerned respiratory, skin, and gastrointestinal 

symptoms among employees exposed to metalworking fluids. We visited the plant four times 

in 2013 and 2014.

What We Did

● We interviewed employees about their medical and work histories, examined 

employees’ rashes, and reviewed employee medical records.

● We asked employees to fill out a questionnaire about 

work exposures and symptoms.

● We took air samples for metalworking fluid mist, 

formaldehyde, and endotoxin.

● We measured machine operators’ metalworking 

fluid mist exposures while videotaping them do 

machining tasks. 

What We Found

● Some machine operators had skin rashes from 

metalworking fluid exposure.

● Some machine operators reported breathing problems.

● Most machine operators were exposed to 

formaldehyde above the NIOSH limit.

● Before the company made changes, most machine 

operators were overexposed to metalworking fluid mist. 

● No employees were overexposed to metalworking fluid mist after the company 

improved ventilation and added splash shields to the compressed air guns.

● Machine operators had brief, high exposures to metalworking fluid mist when they 

blew parts off with compressed air.

What the Employer Can Do

● Reduce the number of times machine operators use compressed air for each part.

● Continue improving metalworking fluid management practices.

● Train employees about the health hazards of metalworking fluids and ways to reduce or 

prevent exposure.

● Periodically measure employee exposures to metalworking fluid mist, formaldehyde, 

and noise.
Page ii Health Hazard Evaluation Report 2013-0075-3264

What Employees Can Do

● Report skin and breathing problems that may be related to work to your supervisor.

● Use compressed air on each part as few times as possible.

● Machine operators should cover their arms and legs to prevent metalworking fluid from 

splashing on them.
Health Hazard Evaluation Report 2013-0075-3264 Page iii

Abbreviations

CFR Code of Federal Regulations

CFU Colony forming unit

EU Endotoxin unit

EU/m3 Endotoxin units per cubic meter of air

LAL Limulus amebocyte lysate

MWF Metalworking fluid

mg/m3 Milligrams per cubic meter

mL Milliliter

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PPE Personal protective equipment

ppm Parts per million

REL Recommended exposure limit
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Health Hazard Evaluation Report 2013-0075-3264 Page 1

Introduction

The Health Hazard Evaluation Program received a request from a manager at an automotive 

engine water pump manufacturer. The manager submitted the request because of employee 

health concerns including respiratory problems, dermatitis, and gastrointestinal problems that 

may be related to metalworking fluid (MWF) exposure. We conducted on-site evaluations in 

March and May 2013. We returned in April 2014 after the company improved engineering 

controls for MWF mists. We provided exposure monitoring result summaries in September 

2013 and June 2014. 

Process Description

The plant produced diesel engine water pumps by machining cast iron with a soluble oil 

MWF. The plant had an employee census that fluctuated from 20–40 employees. Production 

employees worked in either the assembly department or the machining department. The 

plant operated two shifts per day during our 2013 visits and three shifts per day during our 

2014 visits, typically with 4–5 machine operators per shift. Four machining lines (body 

line 1, body line 2, cover line 1, cover line 2) each had a minimum of four fully enclosed 

computer numerical controlled machining centers, each with its own MWF sump, and a parts 

washer. Machine operators manually moved each part through each machining center and 

the parts washer sequentially, also performing quality control measurements on the parts and 

stacking finished parts on pallets at the end of the line. A fifth machining line (pulley line) 

automatically transferred parts among machines, but it required a machine operator (usually 

from cover line 2, adjacent to the pulley line) to stock parts into the beginning of the line and 

take them off at the end of the line. 

All production employees were required to wear safety glasses and steel toe boots. Those 

entering the machining department were also required to wear hearing protection devices. 

Production employees were allowed to wear street clothes. When handling parts, machine 

operators were required to wear breathable fabric gloves coated in polyurethane on the palm 

and fingers. When they handled metal parts coated with MWFs, they also donned extended 

mid-forearm length, cuffed, heavy nitrile gloves. 

To maintain the proper concentration of MWF in their machines, machine operators took 

refractometer readings at the start of their shift and added concentrated MWF or water 

to bring the sump mixture to the desired concentration. A chemical supply company 

representative maintained the proper concentration of triazine-containing biocide (Grotan®) 

in all machining center sumps. Assembly operators moved parts manually through a series of 

machines until the finished cover or body part was assembled. Their final step before placing 

the part on a pallet for shipment was to coat the part with a petroleum-based rust inhibitor, 

either by applying it with a brush or by spraying it with a small hand-pumped sprayer. 
Page 2 Health Hazard Evaluation Report 2013-0075-3264

Methods

The objectives of our evaluation were to: 

1. Assess whether any current employees had dermatitis, respiratory problems, or 

gastrointestinal problems associated with their exposures to MWFs. 

2. Characterize employee exposures to MWF mist (measured as thoracic particulate) and 

select components of MWF mist.

2013 Site Visits

Medical Interviews and Review Review

We invited all 25 production employees to participate in confidential medical interviews. We 

examined their skin if they reported having a current rash. We requested employee medical 

records if an employee reported being medically evaluated for a skin or respiratory problem. 

We also reviewed the company’s Occupational Safety and Health Administration (OSHA) 

Logs for years 2006 through 2013. 

Environmental Assessment

MWF environments contain numerous potential exposure hazards for employees. 

We collected bulk fluid samples for amines (monoethanolamine, diethanolamine, and 

triethanolamine), fungi and bacteria, and endotoxin. Amines are common corrosion-inhibiting 

MWF additives, some of which may contribute to developing occupational asthma [NIOSH 

1998a]. Fungi and bacteria can flourish in water-miscible MWFs. Endotoxin, a component 

of the cell wall in Gram negative bacteria common in water-miscible MWF, can cause acute 

and chronic respiratory health effects [NIOSH 1998a]. We also collected air samples for 

MWF mist, formaldehyde (released from triazine-containing biocides like the one used at 

this plant), and endotoxin; looked at the local exhaust ventilation system; observed employee 

work practices and workplace conditions; and reviewed the chemical storage, labeling, and 

safety data sheet management plan. Table 1 shows the numbers and types of environmental 

samples we collected. Machine operators, assembly workers, forklift drivers, and production 

team leads participated in the air sampling exposure assessment. More detailed information 

about some of these sampling and analytical methods is in Appendix A. Appendix B contains 

additional information on the health effects and occupational exposure limits (OELs) for 

substances we evaluated.
Health Hazard Evaluation Report 2013-0075-3264 Page 3

Table 1. Environmental samples collected during 2013 site visits

Date collected Sample type Number of 

samples

Analyte (analytical method)

3/28/2013 Bulk fluids 10 Solubility testing for future air sampling 

(NIOSH Method 5524*); triazine and 

amines (GC-FID)

5/29–30/2013 Personal air samples

Area air samples

Bulk fluids

30

16

16

8

10

10

MWF (NIOSH Method 5524*)

Formaldehyde (NIOSH Method 2016*)

Endotoxin (LAL) 

Bacteria and fungi (culture)

Triazine, monoethanolamine, 

diethanolamine, triethanolamine (GC-FID)

Endotoxin (LAL)

GC-FID = gas chromatograph with flame ionization detector

LAL = limulus amebocyte lysate assay

*National Institute for Occupational Safety and Health [NIOSH 2016] 

Other Observations

We looked at the local exhaust ventilation associated with each machining center and at the 

building’s general ventilation exhaust fan. We used ventilation smoke tubes to qualitatively 

test several machining centers to see whether the local exhaust ventilation drew air into the 

machine cabinet, out of the machine operator’s breathing zone. To learn about the company’s 

plans for working with hazardous chemicals, we evaluated the company’s chemical and 

safety data sheet management policy. We focused on whether there was a complete written 

chemical inventory (including safety data sheets), what the company’s plans were for 

informing employees of potential chemical exposure risks and how to protect themselves, 

and how to respond safely to small chemical spills. This plan included a description of the 

company’s yet to be fully implemented MWF management practices.

2014 Site Visit

After our 2013 site visits, the company made engineering control improvements (described 

more fully in the Results section of this report) to reduce MWF mist exposures. Anticipating 

that MWF mist exposures may have decreased as a result of those changes, we returned in 

2014 for medical and environmental assessments.

Questionnaires

We asked all 19 permanent nonsupervisory production employees and 4 temporary 

production employees who were available at the time to complete a written questionnaire. 

The questionnaire asked about demographic information, work and medical history, 

personal protective equipment (PPE) use, hygiene habits, and personal exposures. We 

used four questions from the European Community Respiratory Health Survey which have 

been validated for asthma symptoms [Grassi et al. 2003]. The dermatologic questions 
Page 4 Health Hazard Evaluation Report 2013-0075-3264

included standardized questions modified from the Nordic Occupational Skin Questionnaire 

[Susitaival et al. 2003], which is widely used in studies of dermatitis. 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 were defined as work-related symptoms.

In addition to analyzing the data for individual respiratory symptoms and physiciandiagnosed asthma, we also looked at prevalence of “asthma-like symptoms” defined as 

answering “yes” to any of the following questions [Grassi et al. 2003]:

● Are you currently taking any medicine for breathing problems or asthma?

● Have you had wheezing or whistling in your chest in the past 12 months?

● Have you woken up with a feeling of tightness in your chest in the past 12 months?

● Have you had an attack of asthma in the past 12 months?

These questions were intended to identify employees who had asthma-like symptoms but had 

not been diagnosed as having asthma. 

Environmental Assessment

We collected 29 personal air samples and two area air samples for MWF mist and had them 

analyzed by NIOSH Method 5524. We did video exposure monitoring of machine operators 

on two machining lines (cover line 1, body line 2) using a TSI SidepakTM real-time personal 

air monitor (model AM510) to record moment by moment breathing zone thoracic particulate 

concentrations while videotaping those tasks. Thoracic particulate refers to inhaled particles 

that can penetrate beyond the larynx into the respiratory system. The time-stamped air 

monitoring data were combined with the video footage using NIOSH-developed freeware 

(Enhanced Video Analysis of Dust Exposures, http://www.cdc.gov/niosh/mining/Works/

coversheet1867.html) to produce video files showing real-time exposure concentrations for 

all tasks recorded on the video. Additional details about the video exposure monitoring done 

during this survey are in Appendix A. 

Results

2013 Site Visits 

Medical Interviews 

We interviewed 23 of 25 production employees; 2 declined. The 23 participants included 14 first 

shift and 9 second shift employees and consisted of 10 machine operators, 5 assembly operators, 

and 8 who worked in other jobs including floaters, forklift drivers, quality assurance lab personnel, 

planning, and maintenance. Among the 23 interviewed employees, the average age was 42 years 

(range: 19–62 years), the average time worked for this company was 3 years (range: 3 weeks to 7 

years), and the average time in their current job was 2 years (range: 3 weeks to 7 years). 
Health Hazard Evaluation Report 2013-0075-3264 Page 5

Ten of the 23 employees reported current or past medical problems they related to working 

at this plant: five assembly employees, three machinists, and two other production 

employees. Reported health problems included rash (five employees), upper respiratory 

symptoms including nasal congestion, runny nose, throat irritation (three employees with 

sinus symptoms and one employee with throat symptoms), and lower respiratory symptoms 

including cough, wheeze, chest tightness, and shortness of breath (two employees). No 

employees reported gastrointestinal symptoms. 

Four of the five assembly employees had worked as machinists at this plant previously; 

three reported developing a rash when working as machinists and eventually transferring to 

assembly because of their rash. Two of the three reported being medically diagnosed with 

work-related contact dermatitis. Among these three employees with a history of rash, two 

reported the rash cleared after transferring away from MWF, and one reported improvement 

but not complete clearing. Skin examination of this employee revealed signs of chronic 

contact dermatitis (dry, flaking, reddened skin on the hands and wrists). Three of the 

assembly employees also reported sinus and eye symptoms they thought were from the rust 

inhibitor that was sprayed onto the finished parts. One assembly employee also reported hand 

and wrist pain and numbness that was worse because of increased use of their hand at work. 

Two assembly employees reported the presence of more than one medical problem. 

Among the three machinists reporting work-related medical problems, two reported shortness 

of breath, coughing, and labored breathing at work particularly when the large shipping/

receiving bay doors of the plant were closed; one reported developing a rash when heavily 

splashed with coolant. 

Of the two other production employees reporting health problems, one reported developing 

a sore throat and raspy voice only when fresh coolant was added to the MWF. The other 

reported a rash that had improved but not resolved. Upon examination, this employee had skin 

discoloration on the lower extremities that did not appear to be related to work exposures.

When asked if they had any concerns about their work environment or exposures, most 

machine operators reported they were concerned about the lack of ventilation and the 

accumulation of MWF mist in the air over the workday in the machining area. Some reported 

that the air felt “too thick to breathe” at times. Others reported that the MWF was not 

maintained as it should be. Heat and lack of air movement were common concerns. 

Medical Record Review

We reviewed medical records of three employees who reported seeing a medical provider 

for possible work-related illnesses. Two of the employees were diagnosed with work-related 

conditions linked to chemical exposure. One was diagnosed with atypical chest pain after an 

acute chemical exposure, and the second employee was diagnosed with contact dermatitis. 

The employee with chest pain had also reported being diagnosed with work-related contact 

dermatitis, but this evaluation and diagnosis was not included in the medical records. The 

second employee was also diagnosed with carpal tunnel syndrome, which the record states 

may have been aggravated by work. The third employee was diagnosed with conjunctivitis 

(irritation of the membranes in the eye), but the record did not indicate work-relatedness.
Page 6 Health Hazard Evaluation Report 2013-0075-3264

OSHA Log Review

The type and number of entries from the OSHA recordable injury and illness logs from 

2006–2013 are shown in Table 2. The number of entries ranged from 1–8 per year during this 

time period. The most common entries were musculoskeletal disorders and eye injuries.

Table 2. Review of entries from the plant’s OSHA Logs, years 2006–2013

Number of: Year

2006 2007 2008 2009 2010 2011 2012 2013

Total employees 

in the plant

4 19 19 20 33 36 36 40

Total work hours 5520 33,395 38,453 43,315 52,315 69,703 * 85,000

Entries:

Skin — — — 3 — 1 — 1

Respiratory — — — 2 — 1 — —

MSD† — 3 3 — 1 3 1 2

Eye — 3 — — 1 — 2 3

Slip/trip/fall — 1 — — — — 1 1

Cuts, etc.‡ — — 1 3 2 — — —

Other 1 — 1 — — — — —

Total entries: 1 7 5 8 4 5 4 7

*Not included on the OSHA 300A summary for 2012

†Musculoskeletal disorder

‡Lacerations, contusions, abrasions

Environmental Sampling

Metalworking Fluid Mist

Table 3 contains the summary air sampling results for MWF mist in 2013; detailed results are 

in Appendix C, Tables C1 and C2. We compared personal MWF mist sample results to the 

NIOSH recommended exposure limit (REL) of 0.4 milligrams per cubic meter (mg/m3) for 

thoracic particulate mass. 
Health Hazard Evaluation Report 2013-0075-3264 Page 7

Table 3. Summary of full-shift MWF personal air sampling 

results

Job/location Number 

of 

samples

MWF mist 

concentration 

range, (mg/m3)

Machine operator – cover line 1 4 0.37–0.55

Machine operator – cover line 2 

(and pulley line)

4 0.26–0.37

Machine operator – body line 1 5 0.29–0.76

Machine operator – body line 2 5 0.45–0.68

Forklift driving 4 0.24–0.33

Assembly operator 8 0.19–0.25

NIOSH REL — 0.4

% above the NIOSH REL 33 —

% at/above half the NIOSH REL 97 —

Forty-four percent of machine operators’ MWF mist exposures exceeded the NIOSH REL. 

At least one machine operator from all lines but cover line 2 were exposed to MWF mist 

above the REL. The average percentage of extractable material on the air samples was 68%, 

(range: 47%–86%) (Tables C1 and C2 in Appendix C). Machine operators on all machining 

lines frequently used compressed air guns to blow off parts and machine dies. Machining 

centers on cover line 1 and body line 1 were connected to a single large Donaldson Torit® 

WSO model 25-2 mist collector, but none of the others were. When we used ventilation 

smoke tubes to qualitatively assess the direction of airflow at breathing zone height at each 

machining center on body line 1 and cover line 1, we found very few that consistently drew 

the smoke into the machine and into the exhaust ventilation system. Several roll-top garage 

doors in the shipping and receiving department, adjacent to the machining department, 

provided passive natural ventilation when they were open. However, no outdoor air was 

mechanically supplied to the production areas of the plant. 

Formaldehyde

We assessed formaldehyde exposures only for the machine operators. We took 16 personal 

air samples, one on each of four machine operators on both shifts for 2 days. The detailed 

results are in Table C3, Appendix C. Formaldehyde concentrations ranged from 0.041 parts 

per million (ppm) to 0.19 ppm. These results were below the OSHA permissible exposure 

limit of 0.75 ppm and the OSHA action level of 0.5 ppm. One short-term sample (89-minute 

sample time on the pulley line machine operator) indicated the potential for exposures to 

exceed 0.1 ppm, the level at which the OSHA formaldehyde standard (29 CFR 1910.1048[n]) 

requires additional employee safety training. All personal air sample results exceeded the 

NIOSH REL of 0.016 ppm. 
Page 8 Health Hazard Evaluation Report 2013-0075-3264

Endotoxin 

We took 16 full-shift area air samples for endotoxin in the machining department, placing the 

sampling trains atop machining centers. The sampling filters hung at approximately breathing 

zone height and close to the opening machining center enclosure doors wherever possible. 

The results, shown in Table C4, Appendix C, ranged from not detected to 10 endotoxin units 

per cubic meter of air (EU/m3). Because these were area samples, the results are not directly 

comparable to OELs. However, it is helpful to note these concentrations would have been 

well below the 90 EU/m3 exposure limit recommended by the Dutch Expert Committee on 

Occupational Safety [DECOS 2010] had they been collected as personal air samples.

Bulk Fluid Samples

Results from chemical analysis of bulk fluid samples are shown in Tables C5 and C6, 

Appendix C. There are no occupational health limits for triazine or amines in MWF. We 

sought to verify the presence or absence of these chemicals because of the potential health 

effects they can cause and to show their relative abundance compared to each other. Though 

not listed as an ingredient on the safety data sheet, we suspected the soluble oil MWF 

used at this plant (SYN-SOL 7000, Metalloid Corporation) had triethanolamine in it. 

We found that it had triethanolamine and diethanolamine in it. The fresh water used to 

dilute SYN-SOL 7000 for use in the machining centers also had a low concentration of 

triethanolamine but it was below the lab’s quantifiable limit. All used MWF samples had 

triethanolamine in them. More than half of the used MWF samples had monoethanolamine; 

less than half had diethanolamine. No triazine was detected in any sample.

Bacteria and fungi results are shown in Table C7, Appendix C. The Health and Safety 

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

concentrations below 103 colony forming units per milliliter (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 sample concentrations we 

measured (none exceeding 500 CFU/mL) were in the category of “good control” (below 103

CFU/mL) of bacterial contamination. This indicated no further action required to control 

bacterial contamination was needed at that time. The primary organisms (Bacillus spp.) found 

in the used MWF were mostly of the same genera found in the fresh water sample from the 

source used to dilute concentrated MWF for use in machining centers. Aerococcus viridans, 

Pseudomonas alcaligenes, Staphylococcus spp., and Streptomyces spp. were also present. 

Mycobacterium gordonae was isolated only from the fresh water sample. Only one sample 

contained culturable fungi (Cladosporium spp).

Endotoxin concentrations in the bulk MWF samples, shown in Table B8, Appendix B ranged 

between not detected and 160 EU/mL. There are no limits for endotoxin in MWF. 

Metalworking Fluid Management

In 2013, the primary elements of the company’s MWF management program consisted of the 

following: 

1. MWF concentration measurements and fluid additions made by each machine operator 
Health Hazard Evaluation Report 2013-0075-3264 Page 9

each shift for each machining center

2. Periodic triazine biocide additions made by the MWF supplier

3. Periodic sump cleanouts (the most recent was 7 months before our testing)

The company was in the process of implementing a more robust MWF management system, to 

include monthly testing of used MWF for bacteria and fungi, conductivity, and oil sediment. 

Other Observations

We evaluated the company’s chemical and safety data sheet management policy to learn 

about safety plans for working with hazardous chemicals. We observed that staff followed the 

policy’s requirements for safe chemical storage, handling, and labeling of bulk quantities of 

chemicals. We also observed that safety data sheet books were available to staff as described 

in the policy. This policy did not specify plans to effectively inform and train staff about 

hazardous chemicals they may become exposed to or how to work safely during chemical 

spills. It also did not contain a complete list of hazardous chemicals at the plant. We observed 

that production employees consistently wore safety glasses and gloves when handling parts, 

but often wore short sleeves and shorts, with fully exposed arms and legs. Machine operators 

consistently were able to accurately tell us what PPE they had to wear when transferring bulk 

MWF into a smaller container used to add fluid to their machining centers.

On the basis of a recommendation made by a state occupational safety professional, the 

company treated the machining department as a hearing conservation area. As a result, the 

company required people working in the area to wear hearing protection devices. Employees 

had access to earmuffs and several types of Moldex® disposable ear plugs, all of which had 

a noise reduction rating of at least 27 decibels. We observed that some employees did not use 

hearing protection devices when working in the machining department, which increased their 

exposure to potentially hazardous noise. The company informed us of plans to increase the 

number of machines in the machining department, which could increase noise exposures.

2014 Site Visit

Results from our initial environmental assessment led us to focus our attention on MWF 

mist exposures in our follow-up assessment. Before our surveys in April 2014, the company 

made several engineering control improvements to reduce MWF mist exposures. They 

disconnected body line 1 from the large mist collector, thus increasing the amount of exhaust 

ventilation for cover line 1. The company installed Amano® Mistria model MZ-15 mist 

collectors for all other machining centers and Amano Mistria model MZ-10 mist collectors 

on the parts washers. As well, the company installed a general building air-conditioning 

system that they stated brought outdoor air into the work environment. Information about the 

amount of outdoor air brought in by this system was not available. The company also added 

small (approximately 6 inches in diameter) shields to the handheld compressed air guns 

each machine operator used. The shields reduced the amount of MWF mist blowing back 

towards machine operators when they blew metal shavings and MWF out of each part when 

transferring parts between machining centers.
Page 10 Health Hazard Evaluation Report 2013-0075-3264

Questionnaire

Twenty-one production employees participated in the questionnaire including all 17 

permanent nonsupervisory employees who were at the plant during our visit and four of nine 

temporary employees who were available. Ten of the 21 employees had been hired within the 

past year; 5 machinists, 3 assembly, 1 quality assurance, and 1 forklift driver. Nonmachinist 

production jobs included assembly operator (n = 5), quality assurance inspectors (n = 3), 

forklift drivers (n = 2), and planner (n = 1). Employee characteristics are shown in Table 4.

Table 4. Employee characteristics by machining and nonmachining production jobs

Machine operators 

(n = 10)

Nonmachinist production 

employees (n = 11)

Average age in years (range) 39 (23–53) 40 (20–54)

Average no. of months since hired [median]

(range)

24 [11]

(1.5–84)

35 [18]

(1–84)

Number of female employees 2 0

Number handling coolant or parts wet with 

coolant

10 5

Number of employees reporting current smoking 7 4

History of atopy (atopic eczema, asthma, or 

hay fever)

7 5

When asked about medical history, four employees reported a history of childhood asthma. 

All were current smokers, and three were machine operators. Eleven had a history of 

allergic rhinitis/hay fever; seven were machine operators. Two machine operators and two 

nonmachinist production employees reported a history of skin disease. Other than childhood 

asthma, no employees reported a history of a respiratory condition.

Fifteen of the 21 employees reported handling used MWF, called “coolant,” or parts wet 

with MWF in the previous month. Of these 15 employees, 12 reported always wearing 

gloves when doing these tasks, and 3 reported usually wearing gloves. Of those reporting 

any glove use, the black fabric gloves, the green extended cuff nitrile gloves, or both were 

worn. Over half reported wearing one pair of gloves over their entire shift. One employee 

reported always wearing protective sleeves (“yellow plastic”) and three employees reported 

sometimes wearing protective aprons. The employer provided the sleeves and aprons for 

optional use. 
Health Hazard Evaluation Report 2013-0075-3264 Page 11

Information Regarding Symptoms in the Month prior to the 

Questionnaire

Among the 21 employees, 17 (including all 10 machine operators) reported experiencing 

one or more of the symptoms listed in Table 5 in the month prior to our visit; 13 (including 8 

machine operators) reported work-related symptoms, as defined by questionnaire responses. 

No employees reported seeking medical care or taking time off from work because of workrelated symptoms.

All three employees reporting work-related respiratory symptoms (cough, shortness of breath, 

or chest tightness) were machine operators. Machine operators and nonmachinist production 

employees reported work-related eye irritation and runny nose. All employees reporting 

respiratory or nasal symptoms had a history of current or past smoking.

All but one employee reported having the same job during the 12 months prior to the 

survey as they did in the month prior. The one employee remained in a job with similar 

MWF exposure, so the number of machine operators (n = 10) and nonmachinist production 

employees (n = 11) remained the same. Among the 21 employees, nine reported dermatitis 

in the 12 months prior to the survey. Of these, seven were machine operators, and two 

were nonmachinist production employees. When asked if the dermatitis improved away 

from work when away for more than 5 days, five of the seven machine operators and both 

nonmachinist production employees reported improvement. Two machine operators reported 

they had not been away from work more than 5 days. Six machine operators reported that 

they thought MWF caused their rash, and one reported wearing gloves caused a rash. The 

two nonmachinist production employees thought gloves caused their rash. One machine 

operator reported changing jobs to one without MWF exposure because of dermatitis and 

Table 5. Number of employees reporting work-related symptoms in the month prior to the 

NIOSH visit, by job category 

Work-related symptom in the 

month prior to NIOSH visit

No. of machine operators 

reporting (n = 10)

No. of nonmachinist production 

employees reporting (n = 11)

Irritated eyes 3 3

Cough 3 0

Shortness of breath 2 0

Chest tightness 2 0

Wheezing 0 0

Skin redness 3 0

Dry, cracking skin 2 1

Runny nose 2 2 

Sinus problems 1 0
Page 12 Health Hazard Evaluation Report 2013-0075-3264

that the change improved the dermatitis. One machine operator reported seeing a doctor for 

dermatitis who said it was related to work. When asked if they had dermatitis at the time of 

the survey, four machine operators and two nonmachinist production employees reported yes. 

All four machinists reported skin changes on wrists and forearms; three also reported changes 

on hands and fingers. The two nonmachinist production employees reported skin changes 

only on their hands and fingers. These findings suggest that MWF exposure to skin above the 

gloved hands of machinists likely caused their dermatitis. 

We asked certain standardized questions that have been shown to predict asthma [Grassi et 

al. 2003; Susitaival et al. 2003]. When asked these questions, no employees reported asthma 

attacks, episodes of chest tightness, or episodes of illness with two or more respiratory 

symptoms during the 12 months prior to the questionnaire, suggesting that no employees had 

asthma. Two nonmachinist production employees reported wheezing that did not improve 

away from work for 5 days or more in the prior 12 months, suggesting that the symptom was 

likely not related to work. Both had a smoking history. 

Environmental Assessment

Summary results for MWF in personal air samples are below in Table 6; detailed results 

are in Appendix C, Tables C9 and C10. None of the machine operators’ MWF mist samples 

exceeded the NIOSH REL, and fewer than 30% of them were above half the NIOSH REL. 

In contrast, one third of all personal air samples collected during our initial survey were 

above the NIOSH REL, and nearly all (97%) were above half the NIOSH REL. Overall 

exposures were lower in 2014 compared to 2013. However, the average percentage of each 

air sample that was extractable increased from 68% in 2013 to 91% in 2014 (Tables C9 and 

C10, Appendix C), indicating that on average a greater proportion of each sample collected 

in 2014 was liquid aerosol, and not aerosolized particulate, compared to the ones collected 

in 2013. The role of extractable MWF on the respiratory health of exposed employees has 

not been thoroughly differentiated from that of unextractable MWF. NIOSH considers MWF 

mist to consist of the MWF mist itself and all the contaminants in the mist generated during 

machining operations [NIOSH 1998a]. 
Health Hazard Evaluation Report 2013-0075-3264 Page 13

Table 6. Summary of full-shift MWF personal air sampling 

results

Job/location Number of 

samples

MWF mist concentration 

range, (mg/m3)

Machine operator –

cover line 1

1 [0.044]

Machine operator – 

cover line 2 (and 

pulley line)

6 [0.064]–0.31

Machine operator – 

body line 1

4 0.13–0.34

Machine operator – 

body line 2

4 0.13–0.31

Forklift driver 4 [0.083]–0.15

Team lead 2 [0.028, 0.11]

Assembly operator 8 [0.061]–0.26

NIOSH REL 0.4 —

% samples above the 

NIOSH REL

0 —

% samples at/above 

half the NIOSH REL

28 —

[ ] = Concentrations in brackets are between the minimum 

detectable and minimum quantifiable concentrations and have 

more uncertainty associated with them.

Video Exposure Monitoring

When we compared the thoracic particulate mass concentrations collected by the two area air 

samples to the measurements recorded by the real-time air monitors, we found two results that 

are important for properly interpreting the data. First, the thoracic particulate concentrations 

measured by our area air samples were between the minimum detectable concentration and the 

minimum quantifiable concentration, meaning there is more uncertainty associated with them. 

As a result, accurate calibration of the real-time monitor results was not possible. The results 

we report here are considered estimated thoracic particulate concentrations, which are best used 

to assess relative particulate concentrations during different tasks and not for direct comparison 

to OELs. Second, the two area air sample results were 10%–40% lower than the real-time 

concentrations measured at the same time in the same location by the real-time air monitors. 

Therefore, the real-time personal air monitoring results measured during video exposure 

monitoring likely overestimate the true concentration. As such, we refer to these results as 

“estimated thoracic particulate concentration(s).”

We observed brief peaks (ranging 1–12 seconds in duration) in MWF mist concentrations 

that were associated with certain work practices. Machine operators often used compressed 

air to clean metal shavings and excess MWF off machine dies before placing a part inside a 

machine for processing. They also used compressed air (1) to blow metal shavings and MWF 
Page 14 Health Hazard Evaluation Report 2013-0075-3264

out of parts’ holes, channels, and recesses before moving the part further in the machining 

process (Figure 1), and (2) to perform one final blow-off of each finished part before 

stacking it on a pallet with other parts (Figure 2). We saw that sometimes, depending on the 

orientation of the part and the compressed air gun, MWF mist sprayed onto the machine 

operators and into their breathing zone. 

Figure 1. Machine operator holds a part in his gloved left hand, while blowing it off with the 

compressed air gun held in his gloved right hand. Photo by NIOSH.

The final blow-off step on each machining line was supposed to occur within a roughly 

waist-height enclosure (Figure 2), but these blow-off boxes were rarely used during our 

evaluations. Instead, we observed that machine operators tended to allow each part to partly 

drip dry in the blow-off box, then remove the part, hold it up with their hand or place it on 

a nearby shelf or table out in the open, and blow it off using compressed air. During this 

task, the body line 2 machine operator was exposed briefly to as high as 11 mg/m3 estimated 

thoracic particulate (Figure 3). This task was the only one that caused peak exposures for the 

body line 2 machine operator during the time we monitored his exposures. In contrast, the 

cover line 1 machine operator’s peak exposures came from more than just one task but did 

not exceed 2 mg/m3 during the time we monitored.
Health Hazard Evaluation Report 2013-0075-3264 Page 15

Figure 2. Machine operator standing in front of blow-off box, blowing off finished part before placing it 

on pallet to his left. Photo by NIOSH.

Figure 3. Estimated thoracic particulate concentration measured in breathing zone of body line 2 

machinist.
Page 16 Health Hazard Evaluation Report 2013-0075-3264

The timing of certain work practices sometimes affected peak exposures. In some cases, 

a machine finished its machining cycle, the machine cabinet doors opened, but some time 

passed before the machine operator removed the part and advanced it to the next machine. 

In these cases, MWF mist exposures when the machine operator stood between the open 

machine cabinet doors tended to be nearly indistinguishable from those encountered when the 

machine operator was far from a machine, for example at their quality control bench (Figure 

4). Other times, a machine operator waited by the machining center’s door to transfer the part 

just as soon as the doors opened. In these cases, the machine operator sometimes received a 

brief increase in exposure (Figure 4). The OP30 machine in cover line 1 demonstrated these 

effects the most consistently. Most peak exposures, however, were not caused by this timing 

issue but by using compressed air.

Figure 4. MWF mist concentrations measured in breathing zone of machine operator on cover line 1.

Other Observations

We observed work practices similar to what we had initially seen at this plant. Machine 

operators consistently wore safety glasses and gloves, made frequent use of compressed air, 

and commonly had exposed skin on legs and arms. They also occasionally neglected to wear 

hearing protection devices in the area where it is required. Also, at the final blow-off station, 

they commonly removed parts from the blow-off box and blew them down on a nearby 

railing or when holding the part aloft in their other hand.
Health Hazard Evaluation Report 2013-0075-3264 Page 17

Discussion

During our Spring 2013 site visit, machine operators were exposed to MWF mist and 

formaldehyde above the NIOSH REL. The personal air sampling results and airflow patterns 

observed around the machines confirmed that the local exhaust ventilation (mist collectors) 

was not effective in controlling exposures. Additionally, local exhaust ventilation was 

present on only a few machining centers. Interviews found that most machine operators were 

concerned about poor ventilation and inhaling MWF mist. 

Some current and former machine operators reported upper and lower respiratory symptoms 

and skin symptoms consistent with coolant exposure. No employees reported gastrointestinal 

symptoms. Three former machine operators transferred to other work located away from 

MWF exposure because they had developed skin rashes. Two of these employees had 

complete clearing of their rash and one had improvement, but some skin symptoms persisted. 

Skin contact with MWFs is known to 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]. The widespread use of compressed air by machine operators, who often had much 

exposed skin on their arms and legs, presented a plausible route of skin exposure despite 

consistent use of gloves. Inhalation of MWF aerosols may irritate the throat, nose, and lung 

and has been associated with chronic bronchitis, asthma, hypersensitivity pneumonitis, and 

worsening of pre-existing respiratory problems [Burton et al. 2012]. Machine operators’

symptoms were consistent with MWF exposure. These findings suggest that, at the time of 

our initial assessment, control of dermal and respiratory MWF exposure was inadequate.

Between our 2013 and 2014 site visits, the employer made sure all machining centers were 

connected to mist collectors and reduced the “splash back” effect of blowing off parts with 

compressed air guns by installing plastic shields on each air gun in front of the handle. 

When we returned in April 2014, the MWF mist personal air sampling results were all 

below the REL; however, some exceeded half the REL. This means that daily variability 

in workplace conditions could result in some personal exposures exceeding the REL and 

that continued exposure reduction efforts and medical surveillance are warranted. NIOSH 

recommends more frequent air sampling when airborne MWF exposures are more than half 

the REL. Machine operators continued to report work-related respiratory and skin symptoms; 

nonmachinist production employees did not report work-related respiratory symptoms. This 

suggests that MWF exposure was a likely cause of machinists’ symptoms. Formaldehyde is 

also associated with upper and lower respiratory and skin symptoms. No employees reported 

asthma-like symptoms on the questionnaires. 

Some employees can develop respiratory symptoms at MWF levels below OELs like the 

REL [NIOSH 1998a]. 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, 

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

parts manufacturing employee population; 61% of MWF-exposed employees reported 

rhinitis-related symptoms. Air sampling found that 82% of employees at this plant were 
Page 18 Health Hazard Evaluation Report 2013-0075-3264

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]. Overall, the best way to prevent 

upper and lower respiratory symptoms and diseases among MWF-exposed employees is 

to keep MWF mist levels as low as feasible. Additionally, all employees exposed to MWF 

mist should be medically monitored annually, and those who report wheezing, asthmalike symptoms, and work-related asthma-like symptoms need to be referred to a health 

practitioner for medical evaluation. 

Limiting skin exposure is critical to preventing allergic and irritant skin disorders 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 [Jungbauer et 

al. 2004]. Limiting exposure to MWF aerosols is also prudent because previous exposures to 

some MWFs have been associated with increased risk of some types of cancer [NIOSH 2013]. 

Although actions taken in the last several decades have reduced that risk, it is not known if these 

actions have totally eliminated the risk [NIOSH 2013]. Additional information about contact 

dermatitis and tips to reduce or prevent work-related contact dermatitis are given in Appendix D. 

The role of short-term peak MWF mist concentrations in affecting the respiratory and 

dermal health of employees is uncertain. Nonetheless, reducing these short-term exposures is 

prudent. Video exposure monitoring showed that using compressed air to blow off parts and 

machine dies caused the vast majority of peak exposures measured during this evaluation. 

Peak exposures also occurred when a machine operator stood in front of opening machining 

center cabinet doors before the mist collector had time to sufficiently reduce MWF aerosol 

concentrations. This information may provide a starting point for future exposure control 

efforts. Because all the machining centers now have mist collectors on them, there may be 

benefit in delaying the cabinet doors’ opening until the mist collector has adequate time to 

filter the air within the machining center cabinet. Using compressed air the way machine 

operators did at this plant can also contribute to employees’ dermal exposure by blowing 

MWF mist onto unprotected skin [HSE 2011]. Minimizing the use of compressed air, 

and allowing enough time for mist collectors to lower airborne concentrations within the 

machining centers before the cabinet doors open, could lower the risk for respiratory and 

dermal routes of exposure. 

The design of some features within the machining lines contributed to respiratory and dermal 

exposure of employees to MWF mist. The blow-off box at the end of each machining line 

seemed too low (and, on the cover lines, too small) for most of the machine operators to use 

comfortably, providing incentive for them to remove parts before blowing them off. As well, 

because the blow-off boxes were not connected to local exhaust ventilation, and open only 

on the side facing the machine operator, they were not optimized for MWF mist exposure 

prevention. A second feature that likely contributed to MWF mist exposure, as documented 

by video exposure monitoring on cover line 1, was the lack of a splash guard where machine 

operators blew off parts along the parts conveyor between machining centers. The small 

splash shields the company installed were effective a great deal of the time. However, MWF 

mist escaped to the surrounding area depending on the angle of compressed air applied to the 
Health Hazard Evaluation Report 2013-0075-3264 Page 19

part and the depth the air gun nozzle was inserted into the holes and recesses of the part. The 

complexities inherent with solving these exposure challenges underscore the importance of 

first seeking ways to reduce or eliminate the need for machine operators to use compressed 

air on things covered with MWF and metal shavings.

We analyzed bulk MWF for biological and chemical constituents. The culturable analyses of 

bulk MWF indicated well controlled MWF, having virtually no fungal growth and bacteria 

not exceeding 500 CFU/mL of sample [HSE 2006]. However, the samples we collected 

contained no detectable triazine, possibly indicating the eventual need to add biocide to 

maintain low culturable counts of microbes in the future. The endotoxin concentrations in 

bulk MWF were generally lower than those reported in the scientific literature for other 

facilities using similar types of MWF. Simpson and associates found endotoxin ranging from 

the limit of detection to 1,870,000 EU/mL in 154 water-based MWF samples [Simpson et al. 

2003]. The median endotoxin concentration for these samples was 8,039 EU/mL [Simpson 

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

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

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

bearings [NIOSH 2006], but were below 75 EU/mL in an aluminum can manufacturing plant 

[NIOSH 2012]. The health relevance of the low endotoxin concentrations in bulk MWF 

at the plant we visited remains unclear, however. Detecting ethanolamines, particularly 

diethanolamine and triethanolamine, in the process MWF samples was not surprising because 

(1) they are relatively common additives in water miscible MWF [NIOSH 1998a] and (2) the 

unused concentrated MWF (SYN-SOL 7000) contained both these ethanolamines. 

The results from the formaldehyde in air testing indicated a potential health risk. One sample 

indicated the potential for exposures to exceed 0.1 ppm, the level at which the OSHA

formaldehyde standard (29 CFR 1910.1048[n]) requires additional employee safety training. 

The personal air samples for formaldehyde all exceeded the NIOSH REL. The NIOSH REL 

was established in 1981 when NIOSH recognized formaldehyde as a potential occupational 

carcinogen. On the basis of the carcinogen policy in existence at the time, NIOSH set the 

REL to the “lowest feasible concentration.” For formaldehyde, this was defined as the 

analytical limit of quantification of 0.016 ppm for up to a 10-hour TWA and a ceiling limit 

of 0.10 ppm that should not be exceeded [NIOSH 1981]. However, research has shown that 

concentrations of formaldehyde in ambient air can approach or exceed this level [Lemen 

1987]. Additionally, the subsequent revision of the NIOSH carcinogen policy [NIOSH 

1995], combined with better exposure characterization and advances in risk assessment and 

management strategies, support the need for NIOSH to reassess the formaldehyde REL. In 

the meantime, minimizing formaldehyde exposures seems prudent.

The company treated the machining department as a hearing conservation area, requiring 

employees and visitors to wear hearing protection devices. Evaluating potentially hazardous 

noise levels was outside the scope of this health hazard evaluation, but we observed some 

employees neglecting to wear hearing protection devices when in the machining department. 

Adhering to company requirements for using PPE like hearing protection devices is 

an important element of employee health and safety. So is periodically assessing noise 

exposures after making changes in the workplace that could potentially change noise levels.
Page 20 Health Hazard Evaluation Report 2013-0075-3264

Conclusions

Current and former machine operators reported respiratory and skin symptoms consistent with 

work-related exposure to MWF, both before and after ventilation improvements were made 

at this plant. Exposures to MWF mist and formaldehyde were above the REL in 2013 before 

the ventilation improvements, but microbial contaminants in bulk MWF were low. Local 

exhaust ventilation improvements were effective at reducing employees’ MWF mist exposure 

to below the REL. However, workers can develop respiratory illness from MWF exposures 

below the REL. Short-term peak exposures to MWF mist were associated primarily with two 

work practices: using compressed air to blow off machine dies and parts, especially at the last 

station in each machining line, and removing a part from a machining center immediately after 

the cabinet doors open. The company needed to improve several elements of their chemical 

and safety data sheet management program and may need to update their noise exposure risk 

assessment if new machines are added to the machining department.

Recommendations

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

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 plant. 

Our recommendations are based on an approach known as the hierarchy of controls (Appendix 

B). 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. 

Elimination and Substitution

Eliminating or substituting hazardous processes or materials reduces hazards and protects 

employees more effectively than other approaches. Prevention through design, considering 

elimination or substitution when designing or developing a project, reduces the need for 

additional controls in the future.

1. Eliminate the need for machine operators to use compressed air, perhaps by 

developing machining centers that can blow off the part and die as part of each 

machining cycle, inside the enclosed and ventilated machining cabinet. 

2. Substitute biocides with less irritating and sensitizing components if proper fluid 

maintenance and PPE use does not alleviate employee contact dermatitis. Be aware 

that formaldehyde releasing agents such as triazines are known sensitizers, but other, 

less studied chemicals in MWF may also cause contact dermatitis.

3. Switch to a less irritating rust inhibitor spray in the assembly department. 
Health Hazard Evaluation Report 2013-0075-3264 Page 21

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. Adjust machining center operating software settings to allow the cabinet doors to 

remain closed long enough for the mist collectors to adequately lower MWF mist 

concentrations inside. This will minimize machine operators receiving short-term peak 

MWF exposures when the cabinet doors open.

2. Ensure compressed air line pressure used to clean parts and machines stays below 

30 pounds per square inch and that all air guns have splash guards. 

3. Actively ventilate and optimize the height of the blow-off station at the end of each 

machining line. 

4. Add a splash shield to conveyor lines between machining centers so machine operators 

who blow off parts have a barrier between themselves and the MWF mist coming off 

the part they are cleaning.

5. Partially enclose assembly department rust inhibitor spray stations and connect 

exhaust ventilation if switching to a less irritating rust inhibitor is not feasible.

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. Implement fully a comprehensive MWF management program as specified in the 

1998 NIOSH document, “Criteria for a Recommended Standard: Occupational 

Exposure to Metalworking Fluids” [NIOSH 1998a]. 

2. Periodically monitor full-shift employee exposures to MWF mist, noise, and formaldehyde, 

particularly when process changes are made that could affect those exposures. MWF mist 

should be monitored every 6 months until exposures are reduced to below half the REL, 

and then annually thereafter [NIOSH 1998a]. Noise should be monitored at least once 

every 2 years until exposures are consistently below the REL [NIOSH 1998b]. 

3. Develop a training program on the proper handling and use of MWF, the hazards and 

potential health effects associated with MWF exposure, and ways to prevent or reduce 

MWF exposure. Include information on 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 MWF criteria document [NIOSH 1998a]. 

4. Include formaldehyde in the hazard communication program for employees working 

in machining areas. If follow-up air monitoring shows employees’ exposures meet or 
Page 22 Health Hazard Evaluation Report 2013-0075-3264

exceed 0.1 ppm, additional formaldehyde-specific safety training will be required at 

least annually, per 29 CFR 1910.1048(n).

5. Look for health problem or injury trends in company injury and illness logs that may 

be related to particular job duties, work materials, machines, or areas of the plant. 

Evaluate areas or jobs that show an increase in injuries or health problems and develop 

an intervention to reduce exposures. For more information, refer to Chapter 9 in the 

NIOSH MWF criteria document [NIOSH 1998a].

6. Encourage employees to take prompt action when their skin or clothing contacts 

MWFs. For example, exposed skin should be flushed with large amounts of running 

water or washed with soap and water as soon as possible. Residual soap should be 

washed off the skin surface. Clothing contaminated with MWFs should be removed 

and laundered prior to reuse.

7. 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 before 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 

participants. 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 Chapter 9 of 

the NIOSH MWF criteria document [NIOSH 1998a].

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

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

or her.

Personal Protective Equipment

Personal protective equipment 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. Personal protective equipment 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. Encourage the use of protective sleeves and aprons when working with MWFs to 

prevent splash exposures. Exactly which PPE and when it should be used should be 

determined by a hazard assessment with employer and employee involvement. Written 

procedures should define the necessary PPE and include guidance on proper selection 

and use. The PPE should also be inspected, cleaned, or replaced as needed, and 

properly stored according to OSHA requirements [29 CFR 1910.132].

2. Enforce hearing protection device use in hearing conservation areas.
Health Hazard Evaluation Report 2013-0075-3264 Page 23

Appendix A: Methods

Endotoxin

Bulk samples and air samples were analyzed for endotoxin using the Endpoint Chromogenic 

LAL assay, a quantitative test used to detect Gram negative bacterial endotoxin. Samples 

were incubated with the LAL reagent and then a chromogenic substrate reagent causing the 

sample to turn yellow in the presence of endotoxin. After the reaction stopped, the plate was 

read at 405 nm by a plate reader. Sample results were quantified using an endotoxin standard 

curve. Because the polycarbonate air filters used to collect air samples contained endotoxin, 

field sample results were blank corrected using the average endotoxin concentration of the 

filter blanks submitted for analysis with the field samples.

Bulk Sampling for Microbial Analysis

We collected bulk MWF samples using sterile pipettes and 50 mL conical centrifuge tubes. 

The samples were immediately cooled and shipped overnight to the laboratory for analysis. 

The laboratory reported total CFUs plus the top three most prevalent species for each sample.

Bulk Sampling for Chemical Analysis

We collected bulk MWF samples using sterile pipettes and 50 mL conical centrifuge tubes. 

The samples were immediately cooled, and shipped overnight to the laboratory for analysis. 

These samples were analyzed by preparing dilutions of the MWF in acetone, and directly 

injecting an aliquot into a gas chromatograph with flame ionization detection.

Video Exposure Monitoring

The TSI SidepakTM Personal Air Monitor (model AM510) was factory calibrated with Arizona 

road dust which may have different light-scattering and aerodynamic properties than the 

MWF mist in this plant. To help us understand whether this difference affected our results, we 

compared the thoracic particulate mass concentrations collected by the two area air samples 

(which collected MWF mist on filters and were analyzed by NIOSH Method 5524) to the 

results recorded by the real-time air monitors. We collected these two pairs of samples at 

separate machining centers’ operator stations at approximately breathing zone height. 
Page 24 Health Hazard Evaluation Report 2013-0075-3264

Appendix B: 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 exposure. A time-weighted average 

refers to the average exposure during a normal 8- to 10-hour workday. Some chemical 

substances and physical agents have recommended short term exposure limit or ceiling 

values. Unless otherwise noted, the short term exposure limit is a 15-minute time-weighted 

average 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 values, which are recommended by the American Conference of Governmental 

Industrial Hygienists, a professional organization, and the workplace environmental 

exposure levels, which are recommended by the American Industrial Hygiene 

Association, another professional organization. The threshold limit values and 

workplace environmental exposure level are developed by committee members of these 

associations from a review of the published, peer-reviewed literature. These OELs are 
Health Hazard Evaluation Report 2013-0075-3264 Page 25

not consensus standards. Threshold limit values are considered voluntary exposure 

guidelines for use by industrial hygienists and others trained in this discipline “to assist 

in the control of health hazards” [ACGIH 2016]. Workplace environmental exposure 

level 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 Fluid

MWFs are complex mixtures used to cool, lubricate, and remove metal chips from tools 

and parts during machining of metal stock. MWFs often contain other substances including 

biocides, corrosion inhibitors, metal fines, tramp oils, and biological contaminants [Burton 

et al. 2012; NIOSH 1998a]. 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]. Additionally, skin 

contact with MWFs 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]. 
Page 26 Health Hazard Evaluation Report 2013-0075-3264

NIOSH recommends limiting exposures to MWF aerosols to 0.4 mg/m3 for the thoracic 

particulate mass, as a time-weighted average concentration for up to 10 hours per day 

during a 40-hour workweek [NIOSH 1998a]. 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 MWFs at over half the 

REL, or who work in areas where one or more employees have recently developed asthma, 

hypersensitivity pneumonitis, or other serious conditions related to MWF exposure, receive 

medical monitoring, and all employees with exposure to MWF may benefit from medical 

monitoring [NIOSH 1998a]. Medical monitoring is needed for the early identification of 

employees who develop symptoms of MWF-related conditions such as hypersensitivity 

pneumonitis, asthma, and dermatitis. 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. 

Contaminated water in MWFs may also contain fungi. Some fungi may infect susceptible 

hosts, such as immune compromised persons, and exposure to some fungi may result in 

adverse health effects such as hypersensitivity pneumonitis, allergic sensitization, and 

asthma. At this time, health data are insufficient to recommend a specific limit for fungal 

contamination in MWFs.

Triazine

Triazine is the major component of the biocide used at the plant, and exposure to triazine 

may also be a factor in employees’ symptoms. Triethanol triazine (i.e., 1,3,5-triazine-1,3,5-

triethanol) is a formaldehyde-releasing biocide/preservative that is often added to MWF. 

Formaldehyde is a known corrosive and may cause irritant contact dermatitis, in addition 

to eye irritation [EPA 1997]. Although animal studies have not found triethanol triazine to 

be sensitizing (causing an allergic reaction), medical case studies have reported that it has 

caused allergic contact dermatitis in humans [Dahl 1981; Keczkes and Brown 1976; Veronesi 

et al. 1987]. Pre-existing eczematous dermatitis may increase the likelihood of sensitization 

in some individuals. Schnuch et al. found that a 1% concentration of triazine (as Grotan BK) 

produced positive sensitization reactions in 1% of 1,772 patients with suspected allergic 

contact dermatitis [Schnuch et al. 1998]. 

Formaldehyde

Formaldehyde is a microbiocidal breakdown product of triazine, the active ingredient 

in the biocide (Grotan®) added to the MWF at this company. Formaldehyde is also a 

potential dermal sensitizer and respiratory sensitizer [ACGIH 2016]. The NIOSH REL for 

formaldehyde initially was set as low as possible (at the analytical limit of detection at the 

time, [NIOSH 1981]) because formaldehyde is a potential human carcinogen. Additional 

research has shown, however, that sometimes ambient air can have formaldehyde levels 

as high or higher than the NIOSH limit, even with no obvious source nearby. As a result, 

NIOSH is revising its formaldehyde limit and, in the meantime, recommends that employers 

and employees minimize formaldehyde exposures to the extent feasible. The most commonly 
Health Hazard Evaluation Report 2013-0075-3264 Page 27

reported and best documented health complaints due to exposure to low concentrations of 

formaldehyde include irritation of the eyes, nose, and throat; nasal congestion; headaches; 

skin rash; and asthma. Following the NIOSH carcinogen policy in existence at the time, 

NIOSH set the REL to the “lowest feasible concentration.” For formaldehyde, this was 

defined as the analytical limit of quantification of 0.016 ppm for up to a 10-hour timeweighted average and a ceiling limit of 0.10 ppm that should not be exceeded [NIOSH 1981, 

2010]. Since then, experience has shown that this REL is actually not the “lowest feasible 

concentration” because formaldehyde in the ambient air can exceed 0.016 ppm, a fact 

later acknowledged by NIOSH [Lemen 1987]. Additionally, the subsequent revision of the 

NIOSH carcinogen policy [NIOSH 1995], combined with better exposure characterization 

and advances in risk assessment and management strategies, support the need for NIOSH to 

reassess the formaldehyde REL that is in progress.
Page 28 Health Hazard Evaluation Report 2013-0075-3264

Appendix C: Tables

Table C1. Personal air sample results for metalworking fluid mist (thoracic particulate), 

May 29, 2013

Job/Activity Shift Sample time 

(minutes)

Total volume

(liters)

Concentration

(mg/m3)

Percent that 

was extractable

Machine operator – 

Cover line 1

1 581 930 0.52 79

Machine operator – 

Pulley line

1 618 983 0.26 62

Machine operator – 

Body line 2

1 591 946 0.63 72

Machine operator – 

Body line 1 (trainee)

1 586 938 0.29 85

Machine operator – 

Body line 1 (trainer)

1 257 409 0.76 68

Forklift driver 1 607 959 0.24 70

Assembly operator – 

Cummins line

1 551 882 0.26 70

Assembly operator – 

Navistar line

1 549 878 0.23 70

Machine operator – 

Cover line 1

2 641 1,026 0.40 76

Machine operator – 

Cover line 2 & Pulley 

line

2 629 1,006 0.32 72

Machine operator – 

Body line 1

2 628 1,005 0.54 65

Machine operator – 

Body line 2

2 596 954 0.45 86

Forklift driver 2 557 891 0.24 76

Assembly operator 2 594 950 0.24 78

Assembly operator 2 592 947 0.19 47

NIOSH REL 0.4 —
Health Hazard Evaluation Report 2013-0075-3264 Page 29

Table C2. Personal air sample results for metalworking fluid mist (thoracic particulate), 

May 30, 2013

Job/Activity Shift Sample time 

(minutes)

Total volume

(liters)

Concentration

(mg/m3)

Percent that 

was extractable

Machine operator – 

Cover line 2

1 615 984 0.37 83

Machine operator – 

Body line 1 (trainee)

1 613 980 0.30 79

Machine operator – 

Body line 1 (trainer) 

1 572 915 0.62 72

Machine operator – 

Cover line 1 

1 612 979 0.55 69

Machine operator – 

Body line 2

1 598 957 0.68 62

Forklift driver 1 590 944 0.33 52

Assembly operator – 

Navistar line

1 573 917 0.24 55

Assembly operator – 

Cummins line

1 576 922 0.20 67

Machine operator – 

Body line 1

2 626 1,002 0.34 74

Machine operator – 

Cover line 1

2 627 1,003 0.37 68

Machine operator – 

Body line 2

2 627 1,003 0.47 67

Machine operator – 

Cover line 2

2 615 984 0.37 68

Forklift driver 2 557 891 0.24 76

Assembly operator 2 608 973 0.25 46

Assembly operator 2 553 885 0.23 70

NIOSH REL 0.4 —
Page 30 Health Hazard Evaluation Report 2013-0075-3264

Table C3. Machine operator personal air sample results for formaldehyde, May 29–30, 2013

Employee work 

location

Day Shift Sample duration 

(minutes)

Sample volume 

(liters)

Concentration 

(ppm)

Cover line 1 1 1 584 29.8 0.043

Pulley line 1 1 89 4.5 0.19

Body line 2 1 1 405 20.3 0.055

Body line 1 1 1 * * *

Cover line 1 1 2 645 32.4 0.044

Cover line 2 & 

Pulley line

1 2 634 31.7 0.050

Body line 1 1 2 405 20.3 0.043

Body line 2 1 2 599 29.9 0.053

Body line 2 2 1 601 30.1 0.045

Cover line 1 2 1 617 30.9 0.041

Body line 1 2 1 510 25.5 0.043

Cover line 2 2 1 616 30.8 0.041

Body line 1 2 2 521 26.1 0.052

Cover line 1 2 2 630 31.5 0.043

Body line 2 2 2 588 29.4 0.052

Cover line 2 2 2 * * *

NIOSH REL 0.016

OSHA permissible exposure limit 0.75

*Result censored due to pump failure
Health Hazard Evaluation Report 2013-0075-3264 Page 31

Table C4. Area air sample results for endotoxin in May 29–30, 2013

Area Day Shift Sample duration 

(minutes)

Sample volume

(liters)

Concentration

(EU/m3)

Cover line 1 – 

OP210

1 1 553 1,099 3

Body line 1 – 

OP120

1 1 550 1,084 ND

Body line 2 – 

OP120

1 1 547 1,084 4.6

Pulley line – 

above tool door

1 1 545 1,089 3.6

Body line 2 1 2 606 1,212 ND

Body line 1 1 2 * * *

Cover line 1 1 2 607 1,214 3.4

Cover line 2 & Pulley line1 2 606 1,212 5.2

Cover line 1 – 

parts washer

2 1 591 1,182 ND

Body line 1 – 

OP10A

2 1 590 1,180 7.3

Body line 1 – 

between 220 & 230

2 1 589 1,178 4.3

Body line 2 – 

OP110C

2 1 582 1,164 ND

Cover line 1 2 2 609 664 7.8

Body line 1 2 2 609 1,218 8.3

Body line 2 2 2 609 1,218 10

Cover line 2 2 2 332 664 3.7

ND = Not detected; the minimum detectable concentration was 2.3 EU/m3 based on a 

sample volume of 1.1 m3.

*Result censored due to pump failure.
Page 32 Health Hazard Evaluation Report 2013-0075-3264

Table C5. Chemical analysis of bulk metalworking fluid samples, μg/mL, collected March 28, 2013

Sample location Triazine Monoethanolamine Diethanolamine Triethanolamine

Fresh water (used for 

mixing MWF)

ND ND ND [46]

Cover line 1, OP-10A ND [340] ND 2,600

Cover line 1, OP-10B ND ND ND 2,200

Body line 1, OP-10B ND [400] ND 3,000

Body line 1, OP-10B ND ND ND 2,100

Cover line 2, OP-20 ND [430] ND 3,100

Pulley line ND ND ND 2,100

Cover line 1 – 

parts washer

ND ND ND 780

Unused SYN-SOL 

7000

ND* ND* 9700* 31,000*

Body line 2 – 

parts washer

ND ND [530] 2,700

Minimum detectable 

concentration†

40, 400 30, 300 30, 300, 500, 

600, 700, 800

30, 300

Minimum quantifiable 

concentration†

120, 1,300 83, 910 83, 910, 1700, 

2,000, 2,300, 

2,600

83, 910

ND = Not detected

[ ] = Concentrations in brackets are between the minimum detectable concentration and 

minimum quantifiable concentration for that particular sample, and have more uncertainty 

associated with them.

*Sample was too viscous to be analyzed by volume and had to be weighed; units are in 

milligrams per kilogram.

†Some samples required various amounts of dilution prior to analysis, and as a result these 

table values may vary from sample to sample.
Health Hazard Evaluation Report 2013-0075-3264 Page 33

Table C6. Chemical analysis of bulk metalworking fluid samples, μg/mL, collected May 30, 2013

Sample location Triazine Monoethanolamine Diethanolamine Triethanolamine

Cover line 1, OP-10A ND [350] ND 3,000

Cover line 1, OP-40 ND [550] [500] 4,900

Cover line 1, 

parts washer

ND ND ND 1,600

Body line 1, OP-10A ND [510] [550] 4,100

Body line 1, 

parts washer

ND ND [660] 1,800

Body line 1, OP-30 ND [550] [670] 4,300

Body line 2, OP-10C ND [500] [450] 3,800

Body line 2, OP-40 ND [640] 1100 5,700

Cover line 2, OP-230C ND ND ND 1,900

Cover line 2, OP-210C ND [410] ND 2,900

Minimum detectable 

concentration

400 300 300 300

Minimum quantifiable 

concentration

1,300 910 910 910

ND = Not detected

[ ] = Concentrations in brackets are between the minimum detectable concentration and 

minimum quantifiable concentration, and have more uncertainty associated with them.
Page 34 Health Hazard Evaluation Report 2013-0075-3264

Table C7. Microbial analysis of bulk fluids collected March 28, 2013

Fluid type and 

source

Predominant organisms Fungal 

content

Mycobacterial 

content

Used MWF, cover 

line 1 OP220

28 CFU/mL Aerococcus viridans None None

Used MWF, cover 

line 1 OP230

500 CFU/mL Pseudomonas alcaligenes 100 CFU/mL 

Cladosporium 

spp.

None

Used MWF, body 

line 1, OP110A

1 CFU/mL Bacillus spp., morphotype 1

1 CFU/mL Bacillus spp., morphotype 2

1 CFU/mL Bacillus spp., morphotype 3

1 CFU/mL Streptomyces spp.

None None

Used MWF, body 

line 1, OP130

100 CFU/mL Bacillus spp.

100 CFU/mL Staphylococcus spp.

coagulase negative

None None

Used MWF, body 

line 2 OP110B

100 CFU/mL Bacillus spp. None None

Used MWF body 

line 2 robodrill

1 CFU/mL likely Bacillus pumilus None None

Used MWF, cover 

2 body mount 

surface finish

None None None

Fresh water for 

MWF mixing

100 CFU/mL Bacillus spp., morphotype 1

100 CFU/mL Bacillus spp., morphotype 2

100 CFU/mL Staphylococcus spp., 

coagulase negative

None Mycobacterium 

gordonae*

*Isolated from the broth only, and unable to be counted.

Table C8. Endotoxin concentration in bulk fluid samples 

collected May 30, 2013

Sample location Endotoxin, EU/mL

Cover line 1, OP-10A 42

Cover line 1, OP-40 98

Cover line 1, parts washer 2.8

Body line 1, OP-10A 5.7

Body line 1, parts washer 13

Body line 1, OP-30 3.4

Body line 2, OP-10C 160

Body line 2, OP-40 4

Cover line 2, OP-230C ND

Cover line 2, OP-210C 1.7

ND = Not detected; the limit of detection was 1.25 EU/mL.
Health Hazard Evaluation Report 2013-0075-3264 Page 35

Table C9. Personal air sample results for metalworking fluid mist (thoracic particulate), 

April 8, 2014

Title – location Shift Sample time 

(minutes)

Total volume

(liters)

Concentration

(mg/m3)

Percent that 

was extractable

Machine operator – 

Cover line 2

1 503 798 0.16 94

Machine operator – 

Pulley line (plus 

trainee on cover line 2)

1 500 795 0.15 100

Machine operator – 

Body line 1

1 435 690 0.13 86

Machine operator – 

Body line 2

1 505 804 0.20 95

Forklift driver 1 470 746 [0.083] 100

Assembly operator – 

Cummins line

1 542 858 0.24 87

Assembly operator – 

Navistar line

1 543 859 [0.061] 100

Machine operator – 

Body line 2

2 502 801 0.21 95

Machine operator – 

Cover line 2

2 501 796 0.31 93

Machine operator – 

Body line 1

2 456 729 0.13 32

Forklift driver 2 551 876 0.15 94

Assembly operator – 

Cummins line

2 529 843 [0.074] 100

Assembly operator – 

Cummins line

2 527 838 0.13 100

NIOSH REL 0.4 —

[ ] = Result fell between the minimum detectable concentration and the minimum quantifiable 

concentration (0.09 mg/m3 based on an average sample volume of 816L), and has more 

uncertainty associated with it.
Page 36 Health Hazard Evaluation Report 2013-0075-3264

Table C10. Personal air sample results for metalworking fluid mist (thoracic particulate), 

April 9, 2014

Title – location Shift Sample time 

(minutes)

Total volume

(liters)

Concentration

(mg/m3)

Percent that 

was extractable

Machine operator – 

Body line 2

1 492 784 0.31 100

Machine operator – 

Cover line 2

1 209 333 [0.13] 69

Machine operator – 

Pulley line

1 488 778 0.15 100

Machine operator – 

Body line 1

1 485 774 0.19 100

Machine operator – 

Cover line 1

1 754 1,195 [0.044] 56

Forklift driver 1 518 821 0.16 94

Assembly operator – 

Cummins line

1 524 830 0.24 100

Assembly operator – 

Navistar line

1 522 828 [0.075] 95

Team lead 1 501 796 [0.028] 100

Machine operator – 

Body line 2

2 513 817 0.13 100

Machine operator – 

Cover line 2

2 512 815 [0.064] 100

Machine operator – 

Body line 1

2 446 713 0.34 100

Forklift driver 2 586 924 0.10 64

Assembly operator – 

Cummins line

2 586 930 0.26 97

Assembly operator – 

Cummins line

2 583 928 [0.067] 95

Team lead 2 433 687 [0.11] 100

NIOSH REL 0.4 —

[ ] = Result fell between the minimum detectable concentration and the minimum quantifiable 

concentration (0.09 mg/m3 based on an average sample volume of 797 L), and has more 

uncertainty associated with it.
Health Hazard Evaluation Report 2013-0075-3264 Page 37

Appendix D: 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].
Page 38 Health Hazard Evaluation Report 2013-0075-3264

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 

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]. Avoiding 

the use of formaldehyde-releasing biocides in MWF will likely reduce contact dermatitis 

among machinists [Aalto-Korte et al. 2008]. 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 
Health Hazard Evaluation Report 2013-0075-3264 Page 39

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 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 40 Health Hazard Evaluation Report 2013-0075-3264

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Health Hazard Evaluation Report 2013-0075-3264 Page 45

Keywords: North American Industry Classification System 333618 (Other Engine Equipment 

Manufacturing), Indiana, Metalworking fluid, MWF, triazine, formaldehyde, endotoxin, 

respiratory, dermatitis, cast iron, video exposure monitoring 
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Health Hazard Evaluation Report 2013-0075-3264 Page 47

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 and Microbiology Specialists Inc.

Desktop Publisher: Shawna Watts 

Editor: Ellen Galloway 

Industrial Hygiene Field Assistance: Aalok Oza, Wei Gong, Alia El Burai Felix

Logistics: Donnie Booher, Kevin Moore

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]. Investigation of dermal and respiratory exposures to metalworking 

fluids at an automotive parts manufacturer. By Harney JM, Tapp L. 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 2013-0075-3264, 

http://www.cdc.gov/niosh/hhe/reports/pdfs/2013-0075-3264.pdf.
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