Metalworking Fluid 

Exposure at an Aircraft 

Engine Manufacturing 

Facility – Ohio

Lilia Chen, MS, CIH

Francisco Meza, MD, MPH

Naomi Hudson, Dr PH, MPH

Health Hazard Evaluation Report

HETA 2010-0144-3164

August 2012

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2010-0144-3164 Page i

Report Abbreviations................................................................................................ii

Highlights of the NIOSH Health Hazard Evaluation........................iii

Summary .........................................................................................................v

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

Assessment.....................................................................................................2

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

Discussion.................................................................................................... 13

Conclusions................................................................................................. 17

Recommendations.................................................................................... 17

References.................................................................................................... 20

Contents

Acknowledgments Acknowledgments and Availability of Report................................ 37

Appendix A Occupational Exposure Limits and Health Effects......................... 24

Appendix C Tables............................................................................................................. 31

Appendix B Methods........................................................................................................ 27

Appendix D Tips on Preventing Dermatitis.............................................................. 35
Page ii Health Hazard Evaluation Report 2010-0144-3164

Abbreviations

o

C Degrees Celsius

μm Micrometer

ACGIH® American Conference of Governmental Industrial Hygienists

BCYE Buffered charcoal yeast extract

CFR Code of Federal Regulations

CFU/mL Colony forming units per milliliter

CI Confidence interval

EU/m3 Endotoxin unit per cubic meter

HHE Health hazard evaluation

HP Hypersensitivity pneumonitis

LEV Local exhaust ventilation

Lpm Liters per minute

MDC Minimum detectable concentration

mg/m3 Milligrams per cubic meter

mm Millimeter

MQC Minimum quantifiable concentration

MWF Metalworking fluid

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PBZ Personal breathing zone

PPE Personal protective equipment

PEL Permissible exposure limit

PR Prevalence ratio

REL Recommended exposure limit

TLV® Threshold limit value

TWA Time-weighted average

VTL Vertical turret lathe

WEELTM Workplace environmental exposure level
Health Hazard Evaluation Report 2010-0144-3164 Page iii

The National Institute for 

Occupational Safety and 

Health (NIOSH) received 

a request from the United 

Automobile, Aerospace 

& Agricultural Implement 

Workers of America 

to evaluate exposure 

to metalworking fluids 

(MWFs) at an aircraft 

engine manufacturing 

facility in Ohio. The 

requestors were 

concerned about possible 

health hazards from a new 

MWF formulation.

Highlights of the

NIOSH Health

Hazard Evaluation

What NIOSH Did

● We visited the facility in September 2010 and again in May 

2011.

● We asked employees who did and did not work with MWFs 

to fill out a questionnaire about their medical and work 

history.

● We took air samples for MWFs and endotoxin and bulk 

samples of MWF for microbials.

● We reviewed the MWF maintenance and training programs.

● We assessed engineering controls (including ventilation). We 

also looked at work practices.

What NIOSH Found

● Employees who worked with MWFs reported more workrelated asthma symptoms and dermatitis than employees who 

did not work with MWFs.

● All airborne MWF concentrations were very low. These levels 

were below applicable occupational exposure limits.

● Concentrations of endotoxin in the air were very low. These 

levels were below recommended guidelines.

● The central MWF supply systems had good microbial 

control.

● Some employees did not use splash guards, enclosures, and 

mist collectors when machines were in use.

● The preventive maintenance schedule for the mist collectors 

was not always followed.

What Managers Can Do

● Start a medical surveillance program for employees who are 

exposed to MWFs.

● Ensure that employees use engineering controls 

appropriately. These engineering controls can help control 

employees’ exposure to MWFs.

● Follow a preventive maintenance schedule for the mist 

collectors.

● Have employees who work with MWFs wear protective 

sleeves.
Page iv Health Hazard Evaluation Report 2010-0144-3164

Highlights of the

NIOSH Health

Hazard Evaluation

 (continued)

 

● Train employees on MWF health hazards, use of personal 

protective equipment, and proper hygiene.

● Remind employees to report health concerns to their 

manager.

● Refer employees with possible work-related respiratory or 

skin problems to a physician. The physician should be 

knowledgeable about occupational exposures such as MWFs.

What Employees Can Do

● Leave mist collectors on and completely close machine 

enclosures.

● Use splash guards to contain splashing and misting.

● Tell your manager about any injuries or health concerns 

related to your work.

● Take any training that applies to your job when it is offered.

● Use personal protective equipment, such as gloves and 

protective sleeves, to keep MWFs off your skin.

● Wash MWFs off your skin with soap and water as soon as 

possible.

● Maintain good skin health through proper hygiene and use 

of moisturizers.
Health Hazard Evaluation Report 2010-0144-3164 Page v

MWF-exposed 

participants reported 

significantly higher 

rates of work-related 

asthma symptoms and 

work-related dermatitis 

symptoms in the last 12 

months than participants 

not exposed to MWF. 

MWF and endotoxin 

concentrations were 

very low and below 

applicable occupational 

exposure limits. Low 

bacteria counts in the 

bulk MWF samples 

collected from the central 

MWF supply systems 

indicated good microbial 

control. A medical 

surveillance program and 

a healthy skin program 

are recommended for 

early identification and 

prevention of health 

symptoms.

Summary

In July 2010, NIOSH received a request for an HHE from 

a representative of the United Automobile, Aerospace & 

Agricultural Implement Workers of America to evaluate 

exposure to MWFs in an aircraft engine manufacturing 

facility in Ohio. The evaluation focused on workers exposed 

to a new formulation of a semisynthetic MWF introduced in 

January 2010.

We administered questionnaires to employees who worked 

with MWFs and to employees who did not use MWFs. The 

questionnaire asked about demographics, workplace practices 

and location, cigarette smoking, and skin and respiratory 

symptoms. We performed area and PBZ air sampling for MWF 

aerosols (thoracic particulate mass and extracted MWF) in 

the areas fed by the three central MWF supply systems. We 

also performed area air sampling for endotoxin. Bulk samples 

from the central MWF supply systems were collected for 

microbial analysis. We looked at the results of MWF tests done 

regularly at the facility. We also reviewed the company’s MWF 

management program, PPE program, training materials, and 

material safety data sheets.

We found that MWF-exposed participants reported 

significantly higher rates of work-related asthma symptoms 

and of work-related dermatitis symptoms in the last 12 

months than participants not exposed to MWFs. All airborne 

MWF concentrations were below applicable occupational 

exposure limits. Airborne endotoxin concentrations were 

below recommended guidelines. Low bacteria counts in bulk 

samples from the central MWF supply systems indicated good 

microbial control.

We recommended training employees on how to properly 

use engineering controls, such as mist collectors, machine 

partitions, enclosures, and splash guards. Management 

should ensure that the mist collector preventive maintenance 

scheduled is followed. The MWF management program should 

include better documentation of processes and procedures. 

This program should include information on employee 

training, environmental monitoring, and medical screening. 

A medical surveillance program should be started. It should 

include pre-employment and periodic questionnaires about 

respiratory and dermal symptoms. Employees with symptoms 
Page vi Health Hazard Evaluation Report 2010-0144-3164

should be evaluated by a medical professional who is trained 

in occupational health. A healthy skin program should be 

started, which should include teaching employees about 

proper cleansing and use of protective sleeves.

Keywords: NAICS 336412 (Aircraft Engine and Engine Parts 

Manufacturing), metalworking fluid, MWF, thoracic particulates, 

asthma, dermatitis, endotoxin, mycobacteria, microbial 

contamination, fungi, aircraft engine manufacturing
Health Hazard Evaluation Report 2010-0144-3164 Page 1

Introduction

NIOSH received a request for an HHE from the United 

Automobile, Aerospace & Agricultural Implement Workers of 

America to evaluate the possible health hazards of exposure to 

MWFs used as a coolant at an aircraft engine manufacturing 

facility in Ohio. In January 2010, a new formulation of a 

semisynthetic MWF was introduced. This product had lower 

foaming properties than the previous formulation. The new 

MWF was used in the three central MWF supply systems that fed 

approximately 275 machines in one large building.

Various types of aircraft engines were manufactured in a 70-yearold, one-story facility of approximately one million square feet. 

Approximately 360 employees worked in 11 cells (areas) over three 

shifts. Most machines in these cells were served by three central 

MWF supply systems: north, south, and shaft. These systems used 

approximately 20,000 gallons of MWFs. Machining operations 

included grinding, cutting, milling, and drilling. The most 

common machines on the production floor were VTLs, which 

remove material from a rotating work piece with cutting tools, 

mills, and drills. Other machines on the production floor included 

turning centers and grinders. MWFs were used to cool the cutting 

tools and machined parts and to remove metal shavings. Several 

machines not connected to the central supply systems operated 

on their own stand-alone MWF system. The MWFs in these 

stand-alone systems had different formulations from those in the 

central supply systems and MWFs were selected on the basis of 

requirements for specific tasks.

Metalworking Fluids

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 [NIOSH 1998; Burton et al. 2012]. Inhalation of 

MWF aerosols may irritate the throat, nose, and lung and has been 

associated with chronic bronchitis, asthma, HP, and worsening 

of pre-existing respiratory problems [Burton et al. 2012]. HP is a 

spectrum of granulomatous, interstitial lung diseases that occurs 

after repeated inhalation and sensitization to one or more of a 

wide variety of microbial agents (i.e., bacteria, fungi, amoebae), 

animal proteins, and low-molecular weight chemical antigens 
Page 2 Health Hazard Evaluation Report 2010-0144-3164

Sampling for MWF, Endotoxin, and 

Microbials

Full-shift area and PBZ air samples for MWF aerosols (thoracic 

particulate mass and extracted MWF) were collected over 2 days 

of sampling. During the sampling periods, we noted the type of 

engineering and ventilation controls used, location of each sample 

(north, south, or shaft central systems), cutting method (carbide, 

ceramic, or both) and activity performed (e.g., milling or grinding). 

Because each participant was already wearing multiple air sampling 

Introduction

 (continued) [CDC 1996; Kreiss and Cox-Ganser 1997; Zacharisen et al. 1998]. 

NIOSH recommends limiting exposures to MWF aerosols to 0.4 

mg/m3 for the thoracic particulate mass, as a TWA concentration 

for up to 10 hours per day during a 40-hour workweek [NIOSH 

1998]. Detailed information on OELs is presented in Appendix A.

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].

Synthetic, semisynthetic, and soluble oil MWFs are diluted with 

water, so bacteria may grow if an inadequate amount of biocide is 

present. The Health and Safety Executive in the United Kingdom 

states that well-maintained MWFs have bacterial concentrations 

below 103 CFU/mL of fluid [HSE 2006]. Concentrations 

between 103 and 106 CFU/mL indicate reasonable control, and 

concentrations greater than 106 CFU/mL indicate poor control 

[HSE 2006]. The outer cell walls of Gram-negative bacteria may 

release lipopolysaccharide compounds called endotoxin when the 

bacteria die or multiply. Endotoxin is believed to cause adverse 

respiratory effects such as chronic bronchitis and asthma. In 

2010, the Dutch Expert Committee on Occupational Safety 

recommended a health-based occupational exposure limit for 

airborne endotoxin of 90 EU/m3 [DECOS 2010]. Contaminated 

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

susceptible hosts, such as immune compromised persons, and some 

fungi may cause HP. At this time, health data are insufficient to 

recommend a specific limit for fungal contamination in MWFs.

Assessment
Health Hazard Evaluation Report 2010-0144-3164 Page 3

Assessment

 (continued) pumps, we collected area endotoxin air samples at the employees’ 

work stations. Background concentrations of endotoxin were 

collected in a meeting room of a separate building. Additional 

details about MWF and endotoxin sampling and analysis are 

included in Appendix B.

We collected bulk samples of MWFs from each of the central 

supply systems, unused MWFs, and the water that was mixed with 

the concentrated MWFs. Eight bulk MWF samples were collected 

and analyzed by culture for bacteria, mycobacteria (which has been 

associated with HP), and fungi by a commercial laboratory. Details 

on the culture media, incubation temperature, and incubation 

times are contained in Appendix B.

We reviewed reports of the routine tests for MWF parameters, 

material safety data sheets, the MWF management program, MWF 

training materials, and PPE programs.

Exposure Groups

We recruited employees from the first and second shifts in the 

aircraft engine manufacturing building who usually worked 

with MWFs in their current jobs (exposed) and employees in 

an adjacent building who did not work directly with MWFs 

(unexposed). Employees in the unexposed group did assembly 

work, packing, and shipping.

Questionnaire

Participating employees filled out a questionnaire about 

demographics, work practices and location, cigarette smoking, and 

dermal and respiratory symptoms. Other questions addressed use 

of LEV controls, PPE use, and hand hygiene. Data were analyzed 

by age, sex, smoking status, hours worked per week, work area, 

and job title. We compared risk factors and symptoms between 

the exposed and unexposed participants. A P value equal to or 

less than 0.05 was considered significant. A 95% CI that does 

not include one was considered significant. Detailed methods are 

presented in Appendix B.
Page 4 Health Hazard Evaluation Report 2010-0144-3164

Air Sampling for MWFs

On May 5–6, 2011, we collected 48 PBZ air samples (Table C1 in 

Appendix C) and nine area air samples (Table C2 in Appendix C) 

for MWFs. Each sample was analyzed for thoracic particulates and 

the extractable fraction of MWFs. Thoracic particulates include all 

dust and other aerosols in the air (such as bioaerosols) in addition 

to the MWFs. The extractable fraction represents the portion of 

the sample that was MWFs.

Overall, concentrations of thoracic particulates and extracted 

MWFs were very low and did not exceed the NIOSH REL for 

thoracic particulates of 0.4 mg/m3. Of the 48 PBZ air samples 

collected, two were excluded because of missing information 

on the datasheets and wide sampling pump precalibration and 

postcalibration differences. Eighteen of 43 PBZ air samples 

analyzed for thoracic particulates were quantifiable and 25 had 

concentrations between the MDC and MQC. None of the air 

samples had quantifiable concentrations of extracted MWFs, and 

only 4 of 43 PBZ air samples had extracted MWF concentrations 

between the MDC and MQC. Three air samples were taken on 

employees who did not work directly with MWF from the central 

systems (e.g., worked on a machine on a stand-alone system or in 

hot oil flush), but their work stations were surrounded by machines 

that were on the central systems. These concentrations were 

comparable to those found in the other air samples (Table C1).

Machines with various control techniques (e.g., types of enclosures, 

mist collectors) and cutting methods were spread throughout 

the work area. Older machines had splash guards and were 

partially enclosed, whereas newer machines were typically fully 

enclosed and computer operated. Because employees were usually 

assigned to one or two machines at a time during their shift, we 

identified similar exposure groups to evaluate any differences 

in exposures on the basis of control technique. These groups 

were classified by machine enclosure (fully enclosed, partially 

enclosed, no enclosure), ventilation controls (mist collector used 

or not), and cutting method (carbide or ceramic). Employees 

reported that ceramic cutting was performed at faster speeds and 

could cause more misting of MWFs. We observed that samples 

with quantifiable concentrations of thoracic particulates were 

collected mostly at grinders and at machines that did only ceramic 

cutting, although only one or two samples were taken in each of 

Results
Health Hazard Evaluation Report 2010-0144-3164 Page 5

Results

 (continued) these groups. Because no meaningful air sample concentration 

differences were observed and because the number of samples in 

some groups was low, we did not further analyze the data by similar 

exposure groups.

Area air samples for MWFs were taken to supplement the PBZ 

air samples. One area sample was placed next to the north central 

system tank, two were obtained in areas where ceramic cutting was 

done by multiple machines close to each other, and one was taken 

in a different building (where the unexposed participants worked). 

The thoracic particulate air concentrations measured were similar 

to those in the PBZ air samples. No extracted MWF samples were 

quantifiable; two had concentrations between the MDC and MQC 

(Table C2).

Endotoxin

We took 20 area air samples for endotoxin throughout the plant. 

Two samples were taken in a meeting room in a completely separate 

area; one of these samples contained insufficient information 

so it is not reported (Table C3 in Appendix C). Endotoxin 

concentrations in the areas with MWF use ranged from 0.42 EU/

m3 to 2.7 EU/m3 with a mean of 1.2 EU/m3. The meeting room 

sample concentrations were 0.23 EU/m3 and 0.24 EU/m3. Because 

all concentrations were very low and did not vary widely, we did not 

analyze results further by similar exposure groups.

Microbials

Two bulk samples from each of the central systems were collected 

for microbial analysis. An unused sample of MWFs mixed from 

concentrated MWFs and deionized water to the manufacturer’s 

recommended concentration, and a sample of the deionized 

water used to dilute the MWFs were also collected and analyzed 

(Table 1). The highest bacteria counts were in the south central 

system and ranged from 3 to 401 CFU/mL. Two types of bacteria 

were found in the deionized water. Our results showed that all 

bacterial concentrations were low, below 103 CFU/mL of fluid. 

The deionized water also contained four types of fungi. Although 

the shaft central system had no bacteria isolated, Penicillium spp. 

(a fungus) was isolated. The north and shaft central systems also 
Page 6 Health Hazard Evaluation Report 2010-0144-3164

Results

 (continued)

Table 1. Results from microbial analyses of bulk metalworking fluid samples

Bacteria Isolated Fungus Isolated Mycobacteria

Location Bacteria (CFU/mL) Fungus (CFU/mL) Presence

South branch Bacillus spp. 100 None None

GNR, NF, morph* A 300

GNR, NF, morph* B 1

South tank GNR, NF, morph* B 10 Penicillium spp. 1 None

GNR, NF, morph* C 10

GNR, NF, morph* D 100

North tank GNR, NF, morph* E 3 None Present

North branch None None Present

Shaft tank None Penicillium spp. 200 Present

Shaft branch None Penicillium spp. 2 Present

Deionized Corynebacterium spp. 180 Acremonium spp. 3 None

Water Aerobic actinomycetes 6 Penicillium spp. 2

Cladosporium spp. 100

Sterile hyaline mold 2

Unused fluid 

(10.7% MWF)

None None None

*GNR, NF, morph = Gram-negative rod, non fermenter, morphotype

Bulk samples collected by the company at the same time as the 

NIOSH samples had similar results. However, the company’s 

results showed higher bacteria counts (up to 4,000 CFU/mL). 

Fungi were not detected except in the deionized water sample (30 

CFU/mL). Both sets of results showed that the deionized water 

used to dilute the MWF concentrate for the central systems had 

low levels of bacteria.

Other Observations

Overall, the production floor appeared to be clean, and visible 

mist was not present. The MWF maintenance program appeared 

to be comprehensive, but was not well documented, such as having 

had mycobacteria present. These mycobacteria were identified as a 

Ziehl-Neelsen stain species; however, the laboratory was unable to 

identify the exact species.
Health Hazard Evaluation Report 2010-0144-3164 Page 7

Results

 (continued) a written standard operating procedure for testing the fluid. The 

coolant team met biweekly or as necessary, handled issues that 

arose concerning maintenance of the three central MWF supply 

systems, and oversaw activities of the contractor who performed 

daily maintenance of these systems. MWFs in the central systems 

were tested weekly for concentration, pH, conductivity, bacterial 

counts, percent free oil, fungal counts, total anaerobes, and amount 

of stabilizer. Our review of these results indicated that most of the 

parameters fell within the MWF manufacturer’s recommended 

ranges. Parameters outside recommended ranges were bolded on 

the logs, and we were told that the MWF system contractor took 

necessary actions to rectify them in a timely manner.

Preventive maintenance activities, including filter changes on the 

mist collectors, were scheduled annually; however, we were told 

that due to resource limitations, some of these activities had not 

been completed as scheduled. We observed that some machines 

had mist collector systems, enclosures, and splash guards that 

operators did not always use when the machines were in use. In 

specific instances, enclosures and splash guards were not closed 

completely when the machines were in use. In other cases, mist 

collectors were not turned on.

PPE

Everyone in the manufacturing work area was required to wear 

safety glasses. However, we observed some employees not wearing 

safety glasses. This facility had a mandatory hearing conservation 

program for employees at machines where noise sampling 

performed by the company showed levels above the OSHA action 

level. Other employees used hearing protection voluntarily and 

only when needed. Earmuffs and a variety of ear plugs were 

available and stationed in various places in the work area. We 

observed that some ear plugs were not inserted fully in some 

employees’ ears.

Employees were provided with a wide variety of gloves and barrier 

creams for dermal protection. These items were kept in a central 

location accessible to employees. We observed employees wearing 

nitrile, leather, or cut-resistant wrist-length gloves. We observed 

two employees not wearing gloves. We were told that for a few jobs 
Page 8 Health Hazard Evaluation Report 2010-0144-3164

that required fine manual manipulation, employees chose not to 

wear gloves because the gloves interfered with their work. Most 

employees wore short sleeve shirts. Uniforms were not required.

Questionnaire Results 

Four hundred and seven employees completed the questionnaire. 

The participation rate was 82% (183/223) among the exposed 

group and 87% (224/257) among the unexposed group. Ninetyfour percent of participants were aged 45 years or older (Table 2). 

The majority of both exposed and unexposed participants worked 

41 hours or more per week. The proportion of participants who 

currently smoked was similar between groups, although more 

exposed participants were former smokers. The proportion of 

participants who were atopic (history of allergic symptoms such as 

allergic rhinitis, asthma, or eczema) was similar between exposed 

and unexposed.

Table 2. Demographic characteristics of participants by exposure group (n=407)

Characteristics Total Number (%)

Exposed

Number (%)

n=183

Unexposed

Number (%)

n=224

Age

 18–24

 25–34

 35–44

 45–54

 55–64

 65+

 Unknown

2 (<1)

11 (3)

10 (2)

163 (40)

212 (52)

8 (2)

1 (<1)

1 (1 )

—

5 (3)

88 (48)

83 (45)

5 (3)

1 (1)

1 (<1)

11 (5)

5 (2)

75 (33)

129 (58)

3 (1)

—

Sex

 Male

 Female

340 (84)

67 (16)

174 (95)

9 (5)

166 (74)

58 (26)

Smoking Status

 Never

 Former

 Current

 Unknown

190 (47)

152 (37)

59 (15)

6 (1)

75 (41)

79 (43)

26 (14)

3 (2)

115 (51)

73 (33)

33 (15)

3 (1)

Hours Worked/Week

 0–40 Hours

 41+ Hours

192 (47)

214 (53)

69 (36)

113 (64)

123 (55)

101 (45)

Atopy 228 (56) 110 (60) 118 (53)

Results

 (continued)
Health Hazard Evaluation Report 2010-0144-3164 Page 9

Results

 (continued) The prevalence of dermatitis in the last 12 months was statistically 

significantly greater in the exposed group than in the unexposed 

group after controlling for atopy (Table 3). The most common 

location of dermatitis in both groups was the hands or fingers. 

Almost half of those reporting dermatitis in the past 12 months 

in both the exposed and unexposed groups reported having 

dermatitis currently. More exposed participants reported that their 

dermatitis symptoms were reduced with more than 5 days away 

from work (Table 3).

Table 3. Prevalence of dermatitis by MWF exposure category

Exposed 

(n=183)

Number (%)

Unexposed 

(n=224)

Number (%)

PR (95% CI)

Dermatitis in the last 12 months 41 (22) 25 (11) 1.86 (1.20–2.90)

 Location of dermatitis†

 Hands or fingers 30 (16) 21 (9) 1.61 (0.97–2.68)*

 Wrists or forearm 20 (11) 9 (4) 2.45 (1.16–5.17)*

 Face or neck 12 (7) 8 (4) 1.65 (0.70–3.90)*

 Dermatitis currently 20 (11) 12 (5) 1.89 (0.96–3.72)

 Dermatitis better when 

 away from work more than 

 5 days

31 (17) 14 (6) 2.50 (1.39–4.49)

 Changed job because of dermatitis 2 (1) 1 (<1) 2.15 (0.20–23.33)

 Changed glove type or began 

 wearing gloves because of 

 dermatitis

15 (8) 0 (0) —

*Adjusted for atopy

†Some participants reported more than one location of dermatitis

Exposed and unexposed participants were similar in frequency 

of glove use, but exposed participants were significantly more 

likely than unexposed to wear synthetic rubber (51% vs. 41%, P

= 0.049) and leather gloves (49% vs. 27%, P < 0.01). Unexposed 

participants wore gloves to protect against cuts and abrasions 

during assembly work. Hand hygiene practices (use of barrier 

cream, hand washing, use of hand wipes or solvents to clean 

hands) did not differ significantly between exposed and unexposed 
Page 10 Health Hazard Evaluation Report 2010-0144-3164

Results

 (continued)

Table 4. Hand hygiene practices and glove use by dermatitis on the hands or fingers, or wrists or forearms, in the 

last 12 months for exposed and unexposed participants combined

Dermatitis in the last 12 

months 

Number (%)

n=58

No dermatitis in the last 12 

months 

Number (%)

n=348-349*

PR (95% CI)†

Applies barrier cream at 

work 12 (21) 20 (6) 4.64 (2.29-9.37)

Wash hands at least once 

per shift 58 (100) 345 (99) —

Use hand-wipes to clean 

hands at least once per 

shift

33 (57) 186 (53) 1.13 (0.87–1.46)

Applies moisturizing lotion 

to hands or arms at work 31 (53) 190 (55) 0.98 (0.75–1.28)

Uses solvents to clean 

hands at work 8 (14) 24 (7) 2.23 (1.00–4.96)

Use gloves all of the time 19 (33) 90 (26) 1.33 (0.87–2.04)

Use gloves at least 

some of the time 56 (97) 320 (92) 1.07 (0.98–1.17)

 *Denominators vary because of missing information

†Adjusted for atopy

participants. For the most part, hand hygiene practices, glove 

use, and glove type did not differ significantly between those who 

reported dermatitis on their hands or fingers or wrists or forearms 

in the last 12 months and those who did not (Table 4). However, 

participants with dermatitis on their hands or fingers or wrists or 

forearms in the last 12 months were significantly more likely to 

apply barrier cream at work (Table 4). Only 22% (9/41) of exposed 

participants with dermatitis in the last 12 months reported seeing 

a doctor for their dermatitis. Of these, none had patch testing.
Health Hazard Evaluation Report 2010-0144-3164 Page 11

Results

 (continued) The proportion of participants who reported ever having asthma 

was similar between the exposed (11%) and unexposed groups 

(9%). About one third of those who reported ever having asthma 

reported that their asthma began during their current job. The 

prevalence of reported asthma symptoms by exposure group 

are in Table 5. These symptoms are taken from the European 

Community Respiratory Health Survey; a positive answer to any 

one indicates potential asthma (detailed information about the 

European Community Respiratory Health Survey can be found in 

Appendix B). The prevalence of work-related wheezing or whistling 

in the chest was significantly higher for the exposed than the 

unexposed participants (Table 5). The prevalence of participants 

who reported at least one asthma symptom and at least one workrelated asthma symptom was significantly greater for participants 

exposed to MWFs than for unexposed participants after 

controlling for cigarette smoking status (Table 5). Because the REL 

is for a 40-hour work week, we compared the prevalence of asthma 

symptoms and work-related asthma symptoms between exposed 

participants who worked 40 hours per week or less and those who 

worked more than 40 hours per week. There was no significant 

difference between these groups.

The prevalence of sneezing, runny nose, or blocked nose was 

similar between exposed and unexposed participants; however, the 

prevalence of work-related nasal symptoms was significantly higher 

among the exposed (PR 1.36; CI: 1.003–1.86).

The prevalence of reported symptoms of HP by either of our 

definitions did not differ between exposed and unexposed 

participants. Six percent of exposed and unexposed participants 

reported one or more episodes of fever and weight loss in the last 

12 months plus at least two of cough, wheeze, shortness of breath, 

or chest tightness. Less than 1% of participants in each group 

reported having pneumonia or chest flu more than twice in the last 

12 months.
Page 12 Health Hazard Evaluation Report 2010-0144-3164

Results

 (continued)

Table 5. Prevalence of asthma symptoms by exposure category*

Symptoms

Exposed

(n=183)

Number (%)

Unexposed

(n=224)

Number (%)

PR (95% CI)

Wheezing or whistling in chest†

 Breathless when wheezing or whistling

 Wheezing or whistling without a cold

 Wheezing or whistling better on days 

off/vacation 

46 (25)

18 (10)

37 (20)

32 (17)

35 (16)

19 (9)

26 (12)

14 (6)

1.54 (1.03–2.29)

1.13 (0.61–2.10)

1.66 (1.04–2.66)

2.84 (1.56–5.18)

Attack of asthma† 6 (3) 6 (3) 1.22 (0.40–3.76)

 Attacks of asthma less often on days 

off/vacation

5 (3) 5 (2) 1.21 (0.35–4.13)

Woke up with feeling of tightness in chest† 

 Episodes of chest tightness less often 

on days off/vacation

26 (14)

18 (10)

13 (6)

10 (4)

2.47 (1.30–4.69)

2.22 (1.05–4.72)

Currently taking any medicine for asthma† 10 (5) 12 (5) 1.05 (0.46–2.39)

 Take medicine less often on days 

 off/vacation

5 (3) 3 (1) 2.28 (0.55–9.42)

Asthma symptoms‡ 

 Work-related asthma symptoms 

54 (30)

37 (20)

43 (19)

24 (11)

1.49 (1.05–2.13)

1.92 (1.19–3.09)

*Controlled for smoking status

†Derived from European Community Respiratory Health Survey; positive answer to any one indicates potential 

asthma

‡Asthma symptoms based upon a positive answer to one or more of four European Community Respiratory 

Health Survey questions
Health Hazard Evaluation Report 2010-0144-3164 Page 13

Discussion

Airborne MWF concentrations in this facility were generally 

well controlled, and none exceeded the NIOSH REL of 0.4 mg/

m3 for the thoracic particulate mass, as a TWA concentration 

for up to 10 hours per day during a 40-hour week. Because some 

employees reported working longer than 40 hours per week, this 

REL may be lowered by a reduction factor depending on the 

duration of exposure. We observed that samples with quantifiable 

concentrations of thoracic particulates were collected mostly at 

grinders and at machines that did only ceramic cutting. Although 

only one or two samples were taken in each of these similar 

exposure groups, other studies have found that grinding can 

generate higher concentrations of MWF mist than milling and 

turning [Simpson et al. 2003].

Mist collectors were installed on most of the machines that used 

MWFs. The mist collectors pulled air containing MWF mist 

from the area of the mist-generating activity through a highefficiency particulate air filter and released the filtered air back 

into the work area. Mist collectors’ performance degrades over 

time from various causes such as dust or contaminant buildup 

and mechanical failures. Therefore, if the filters are not replaced 

regularly and the performance parameters are not periodically 

checked, mist collectors lose the ability to maintain designed 

airflow requirements, which could expose workers to higher MWF 

concentrations. Adhering to a preventive maintenance plan to 

ensure optimum LEV performance will provide long-term worker 

protection from exposures and capitalize on the initial investment 

in the mist collectors [ACGIH 2007].

Wiring mist collectors so that they automatically turn on when 

the machine is in use would reduce the burden on the operator. 

Mist collectors should also be used as designed for optimum 

performance of drawing air contaminants away from the worker. If 

the machine’s mist collector system was designed to be used with 

the enclosures in place, leaving the enclosures open could reduce 

capture efficiency and increase exposures.

The highest endotoxin concentration measured (2.7 EU/m3) was 

well below the Dutch Expert Committee on Occupational Safety 

recommendation of 90 EU/m3 for airborne endotoxin. Most of 

our endotoxin sampling results were much lower than those cited 

in other studies. Gilbert et al. found endotoxin levels ranging 

from 2.1 EU/m3 to 183 EU/m3 at 44 sites from 25 industries 

using MWFs in Quebec, Canada [Gilbert et al. 2010]. Another 
Page 14 Health Hazard Evaluation Report 2010-0144-3164

study measuring area endotoxin concentrations at a facility using 

semisynthetic MWFs in turning lathe and milling machining 

centers and a facility machining large and small parts using 

semisynthetic and synthetic MWFs found concentrations that 

ranged from 3.3 to 127 EU/m3 [Wang 2007].

Our results showed good bacterial control in this facility based 

upon HSE recommendations of bacterial concentrations below 103

CFU/mL of fluid [HSE 2006]. The company’s results showed good 

control overall because all bacterial counts fell below the 103 CFU/

mL recommendation except for one sample. This sample had 

4,000 CFU/mL, which indicated reasonable control [HSE 2006]. 

Mycobacteria of the Ziehl-Neelsen stain were present in the bulk 

samples, but the laboratory was unable to isolate the exact species 

for identification. Because mycobacteria have been found in MWFs 

in workplaces with HP outbreaks [Kreiss and Cox-Ganser 1997], 

bioaerosol control should be practiced to prevent the occurrence of 

HP [Passman et al. 2009].

Typically, fungi isolated from MWFs are common saprophytic 

species that live on decaying organic matter in the environment. 

Although present, fungi usually are not a major microbial 

contaminant in MWFs. The Penicillium species, which we found 

in the MWF in this facility, has been implicated in HP, but the 

relationship between fungal contamination and occupational 

asthma associated with MWF exposures is uncertain [NIOSH 1998].

While we did not find a difference in the occurrence of HP 

symptoms between exposed and unexposed employees, others 

have found cases of work-related HP in employees exposed to 

MWFs below the NIOSH REL [Kreiss and Cox-Ganser 1997]. 

The company’s clinical staff was aware of HP in the past, but no 

cases had occurred recently. HP is rare and often misdiagnosed 

making it difficult to detect. Employees with fever, weight loss, 

cough, shortness of breath, wheeze, chest tightness, chest flu, 

or pneumonia should be evaluated by a healthcare provider 

knowledgeable about HP who can monitor symptoms to ensure 

early diagnosis and treatment.

Despite the low airborne concentrations of MWF, exposed 

participants were significantly more likely to report asthma 

symptoms and work-related asthma symptoms than unexposed 

participants. However, there was no significant difference when 

employees were asked if they ever had asthma. This might be due 

Discussion

 (continued)
Health Hazard Evaluation Report 2010-0144-3164 Page 15

Discussion

 (continued) to underdiagnosis of asthma; Milton et al. suggested that asthma is 

underreported in the workplace [Milton et al. 1998]. Case reports 

of occupational asthma have demonstrated that the NIOSH REL 

for MWFs did not consistently protect against allergic respiratory 

sensitization [Kreiss and Cox-Ganser 1997; Mapp et al. 2005]. 

NIOSH recognized that the REL might not be protective of all 

employees when it was developed [NIOSH 1998].

Contact dermatitis results from skin contact with MWFs and 

can be irritant, allergic, or both [Rom 2007]. Contact dermatitis 

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. Usually only a small percentage of people are susceptible 

to skin allergens. Exposed areas of skin, such as hands and forearms, 

have the greatest contact with irritants or allergens and are most 

commonly affected [Warshaw et al. 2003]. 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. Skin patch testing is 

required to distinguish between the two. In our evaluation, exposed 

participants were significantly more likely to report dermatitis in 

the last 12 months. Wrist and forearm dermatitis was significantly 

more prevalent among exposed participants, but hand dermatitis, 

while more common in exposed participants, was not significantly 

higher. We noted many employees wearing short sleeves, which may 

allow wrist and forearm contact with MWFs, while the hands are 

protected by gloves.

Frequency of glove use was similar between exposed and 

unexposed participants, and between those with and without 

dermatitis, but this does not rule out the possibility that glove 

use may be related to dermatitis for some employees in either 

group. Protective gloves can reduce or eliminate skin exposure 

to hazardous substances if used correctly, but may actually cause 

or worsen hand dermatitis (contamination by permeation and 

penetration) if selected poorly and used improperly [Foo et al. 

2006]. Gloves may hold/keep irritants or allergens next to the 

skin [Kwon et al. 2006]. In addition, certain components of gloves 

are allergens themselves, and merely wearing gloves can lead to 

sweating and irritant dermatitis. Often if working in a water-tight 

glove, it is best to place a breathable cotton glove underneath 
Page 16 Health Hazard Evaluation Report 2010-0144-3164

Discussion

 (continued) the occlusive glove. Similarly, the excessive pursuit of personal 

hygiene in the workplace may actually lead to misuse of soaps 

and detergents and cause irritant contact dermatitis. Proper hand 

washing methods and adequate moisturizing are valuable in 

preventing contact dermatitis [Warshaw 2003].

Those with dermatitis in our evaluation reported using barrier 

creams significantly more often than those without dermatitis. It is 

not clear if they were using the cream because they had dermatitis 

or if the dermatitis was caused or exacerbated by the barrier cream. 

The effectiveness of barrier creams is controversial. Evidence of the 

protective nature of these topical products during actual working 

conditions is limited [Schwantiz et al. 2003; Loffler et al. 2006; 

Weisshaar et al. 2006].

Solvents are able to dissolve grease and fat. When skin is exposed 

to solvents, solvents may remove the fat from the skin, causing 

dryness, scaling, and fissuring of the hands [Rom 2007]. Some 

solvents may also allow other chemicals to penetrate the skin more 

easily [OSHA 2008]. Solvents should not be used directly on the 

skin. Six percent of exposed participants and 5% of unexposed 

participants reported using solvents to clean their hands at work, 

but the prevalence of hand and finger dermatitis, and wrist and 

forearm dermatitis was higher among those exposed to MWFs.

Limitations of this work include the cross-sectional design of the 

evaluation. Cross-sectional studies collect information on exposures 

and health outcomes at the same time, so that causality cannot be 

proven. Industrial hygiene sampling can only document exposures 

on the days of sampling in the locations sampled. In addition, 

we did not perform clinical examinations to diagnose dermatitis 

and asthma. However, the European Community Respiratory 

Health Survey has a sensitivity of 75% and a specificity of 80% 

for asthma symptoms on the basis of a clinical examination with 

immunoglobulin E testing against common allergens, spirometry, 

and methacholine challenge testing [Grassi et al. 2003]. The 

dermatologic questions include standardized questions modified 

from the Nordic Occupational Skin Questionnaire [Susitaival et al. 

2003], which is widely used in studies of dermatitis.
Health Hazard Evaluation Report 2010-0144-3164 Page 17

Conclusions

Participants exposed to MWFs reported significantly higher 

prevalence rates of work-related dermatitis and work-related asthma 

symptoms in the last 12 months than participants not exposed to 

MWFs. Dermal and respiratory symptoms were reported despite 

airborne exposure to MWFs below the REL. Following a preventive 

maintenance program for the mist collectors and appropriate use 

of engineering controls (i.e., machine enclosures, splash guards, 

mist collectors) will help lower airborne levels of MWFs. Instituting 

a medical surveillance program can provide earlier identification of 

potential problems.

Recommendations

On the basis of our findings, we recommend the actions listed 

below to create a more healthful workplace. We encourage you 

to use a labor-management health and safety committee or 

working group to discuss the recommendations in this report and 

develop an action plan. Those involved in the work can best set 

priorities and assess the feasibility of our recommendations for 

this specific situation. We also recommend referring to the OSHA 

document “Metalworking Fluids: Safety and Health Best Practices 

Manual” [OSHA 1999], which contains best practices to assist 

employers in providing safe and healthful workplace for workers 

exposed to MWF through effective prevention programs. Our 

recommendations are based on the hierarchy of controls approach 

(refer to Appendix A: Occupational Exposure Limits and Health 

Effects). 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/or PPE may be needed.

Engineering Controls

Engineering controls reduce exposures to employees by removing 

the hazard from the process or placing a barrier between the 

hazard and the employee. Engineering controls are very effective 

at protecting employees without placing primary responsibility of 

implementation on the employee.

1. Enforce the use of available engineering controls. Use 

partitions and splash guards as recommended by the 

machine manufacturer.
Page 18 Health Hazard Evaluation Report 2010-0144-3164

2. Wire mist collectors to automatically turn on when the 

machine is in use.

3. Prioritize and perform the scheduled preventive 

maintenance on the mist collectors. Refer to the Industrial 

Ventilation Manual of Recommended Practice for Operation 

and Maintenance for specific recommended practices for 

maintaining mist collector effectiveness [ACGIH 2007].

Administrative Controls

Administrative controls are management-dictated work practices and 

policies to reduce or prevent exposures to workplace hazards. The 

effectiveness of administrative changes in work practices for controlling 

workplace hazards is dependent on management commitment and 

employee acceptance. Regular monitoring and reinforcement are 

necessary to ensure that control policies and procedures are not 

circumvented in the name of convenience or production.

1. Improve documentation of the MWF management program. 

MWF management programs include a written standard 

operating procedure for testing MWF, a data collection 

and tracking system, safety and health training, exposure 

monitoring, employee participation, hazard prevention and 

control, and medical monitoring [OSHA 1999].

2. Maintain bacterial concentrations below 1,000 CFU/mL 

[HSE 2006]. Consider filtering bacteria from the deionized 

water used to mix with unused MWF.

3. Provide training on hand hygiene and ensure that employees 

do not wash hands with solvents.

4. Start a medical surveillance program for employees who 

are exposed to MWFs. At a minimum, use a medical 

questionnaire that focuses on skin and respiratory symptoms 

that may be work related. The questionnaire should be 

given prior to placement in a job with MWF exposure 

and periodically thereafter. In addition, employees should 

report work-related skin, eye, and respiratory symptoms 

to their supervisor. Employees who report work-related 

symptoms should be evaluated by a physician experienced 

in occupational medicine or allergy. If employees develop 

occupational rhinitis or asthma, they should be removed 

from exposure to MWF and placed in a job without MWF 

exposure while maintaining their earnings, seniority, and 

other rights and benefits.

Recommendations 

(continued)
Health Hazard Evaluation Report 2010-0144-3164 Page 19

Recommendations 

(continued) 5. Refer employees with recurrent or persistent skin symptoms 

in a timely manner to a dermatologist knowledgeable about 

occupational skin diseases and skin patch testing. Allergic 

contact dermatitis can be diagnosed definitively only with 

skin patch allergy testing. Skin patch testing allows these 

employees to know if they have skin allergy to certain 

workplace substances, as well as to other common skin 

allergens. The results can be used to counsel employees 

individually on what substances to avoid to prevent 

dermatitis recurrence. If these protective methods fail to 

relieve the dermatitis symptoms, then removal from exposure 

may be necessary. In some cases of allergic skin disease, 

employees may have to be reassigned to areas where exposure 

is minimal or nonexistent with retention of earnings, 

seniority, and other rights and benefits.

6. Provide annual healthy skin program training in the fall to 

help employees remember preventive measures they can take 

to protect their skin from drying out in winter. Employees 

with a history of allergic disease should be informed that 

they are at increased risk for developing contact dermatitis 

and need to take extra precautions to keep their skin healthy. 

See Appendix D for tips on preventing dermatitis. Healthy 

skin is one of the best protections against irritant and allergic 

contact dermatitis.

Personal Protective Equipment 

PPE is the least effective means for controlling employee 

exposures. Proper use of PPE requires a comprehensive 

program and calls for a high level of employee involvement and 

commitment to be effective. The use of PPE requires the choice 

of the appropriate equipment to reduce the hazard and the 

development of supporting programs such as training, change-out 

schedules, and medical assessment if needed. PPE should not be 

relied upon as the sole method for limiting employee exposures. 

Rather, PPE should be used until engineering and administrative 

controls can be demonstrated to be effective in limiting exposures 

to acceptable levels.

1. Ensure gloves used by employees are appropriate for the task. 

Discontinue the use of natural rubber latex gloves. Natural 

rubber latex can lead to serious allergy (rhinitis, asthma, 

hives, and anaphylaxis).
Page 20 Health Hazard Evaluation Report 2010-0144-3164

ACGIH [2007]. Industrial ventilation. A manual of 

recommended practice for operation and maintenance. 

Cincinnati, OH: American Conference of Governmental 

Industrial Hygienists.

Burton CM, Crook B, Scaife H, Evans GS, Barber CM [2012]. 

Systematic review of respiratory outbreaks associated with 

exposure to water based metalworking fluids. Ann Occup Hyg 

[epub online ahead of print – doi:10.1093/annhyg/mer121].

Centers for Disease Control and Prevention (CDC) [1996]. 

Biopsy-confirmed hypersensitivity pneumonitis in automobile 

production workers exposed to metalworking fluids – Michigan, 

1994–1995. MMWR 45(28):606–610.

DECOS [2010]. Endotoxins: health-based recommended 

occupational exposure limit. The Hague: Health Council of 

the Netherlands, Dutch Expert Committee on Occupational 

Safety. [http://www.gezondheidsraad.nl/sites/default/

files/201004OSH.pdf]. Date accessed: April 2012.

Foo CC, Goon AT, Leow YH, Goh CL [2006]. Adverse skin 

reactions to personal protective equipment against severe acute 

respiratory syndrome–a descriptive study in Singapore. Contact 

Dermatitis 55(5):291–294.

Gilbert Y, Veillette M, Meriaux A, Lavoie J, Cormier Y, 

Duchaine C [2010]. Metalworking fluid-related aerosols in 

machining plants. J Occup Environ Hyg 7(5):280–289.

Grassi M, Rezzani C, Biino G, Marinoni A [2003]. Asthma-like 

symptoms assessment through ECRHS screening questionnaire 

scoring. J Clin Epidemiol. 56(3):238–247.

Recommendations 

(continued) 2. Place a breathable cotton glove underneath non-breathable 

gloves.

3. Consider the use of protective sleeves to prevent MWFs from 

getting on wrists and forearms.

4. See Appendix D for tips on preventing dermatitis.

5. Provide additional training on the proper use of hearing 

protection.

References
Health Hazard Evaluation Report 2010-0144-3164 Page 21

References

 (continued)

 

HSE (Health and Safety Executive) [2006]. Managing sumps 

and bacterial contamination - control approach 4. COSHH 

essentials for machining with metalworking fluids. [http://www.

hse.gov.uk/pubns/guidance/mw05.pdf]. Date accessed: April 

2012.

Kreiss K, Cox-Ganser J [1997]. Metalworking fluid-associated 

hypersensitivity pneumonitis: a workshop summary. Am J Ind 

Med 32(4):423–432.

Kwon S, Campbell LS, Zirwas MJ [2006]. Role of protective 

gloves in the causation and treatment of occupational irritant 

contact dermatitis. J Am Acad Dermatol 55(5):891–896.

Loffler H, Bruckner T, Diepgen T, Effendy I [2006]. Primary 

prevention in health care employees: a prospective intervention 

study with a 3-year training period. Contact Dermatitis 

54(4):202–209.

Mapp CE, Boschetto P, Maestrelli P, Fabbri LM [2005]. 

Occupational asthma. Am J Respir Crit Care Med 172(3):280–

305.

Milton DK, Solomon GM, Rosiello RA, Herrick RF [1998]. 

Risk and incidence of asthma attributable to occupational 

exposure among HMO members. Am J Ind Med 33(1):1–10. 

NIOSH [1998]. Criteria for a recommended standard. 

Occupational exposure to metalworking fluids. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers 

for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, Publication No. 98-102.

OSHA [1999]. Metalworking fluids: safety and health best 

practices manual. Washington, DC: U.S. Department of Labor, 

Occupational Safety and Health Administration. [http://www.

osha.gov/SLTC/metalworkingfluids/metalworkingfluids_

manual.html]. Date accessed: May 2012.

OSHA [2008]. OSHA technical manual. Washington, D.C.: 

Department of Labor, Occupational Safety and Health 

Administration, Section 2, Chapter 12. [http://www.osha.gov/

dts/osta/otm/otm_ii/otm_ii_2.html]. Date accessed: April 

2012.
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References

 (continued) Passman FJ, Rossmoore K, Roosmoore L [2009]. Relationship 

between the presence of mycobacteria and non-mycobacteria 

in metalworking fluids. Tribology & Lubrication Technology, 

pp. 52–55. [http://www.stle.org/assets/document/52_

Mycobacteria.pdf]. Date accessed: April 2012.

Rom WN [2007]. Environmental and occupational medicine. 

4th ed. Philadephia, PA: Lippincot Williams & Wilkins, pp. 

620–627.

Schwanitz HJ, Riel U, Schlesinger T, Bock M, Skudlik C, 

Wulfhorst B [2003]. Skin care management: educational 

aspects. Int Arch Occup Environ Health 76(5):374–381.

Simpson AT, Stear M, Groves JA, Piney M, Bradley SD, Stagg S, 

Crook B [2003]. Occupational exposures to metalworking fluid 

mist and sump fluid contaminants. Ann Occup Hyg 47(1):17–

30.

Susitaival P, Flyvholm MA, Meding B, Kanerva L, Lindberg 

M, Svensson A, Olafsson JH [2003]. Nordic Occupational 

Skin Questionnaire (NOSQ-2002): a new tool for surveying 

occupational skin diseases and exposure. Contact Dermatitis 

49(2):70–76.

Wang H, Reponen T, Lee SA, White E, Grinshpun SA [2007]. 

Size distribution of airborne mist and endotoxin-containing 

particles in metalworking fluid environments. J Occup Environ 

Hyg 4(3):157–165.

Warshaw E, Lee G, Storrs FJ [2003]. Hand dermatitis: a 

review of clinical features, therapeutic options and long-term 

outcomes. Am J Contact Dermat 14(3):119–137.

Weisshaer E, Radulescu M, Bock M, Albrecht U, Diepgen TL 

[2006]. Educational and dermatological aspects of secondary 

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Safety & Health Assessment & Research for Prevention 

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Page 24 Health Hazard Evaluation Report 2010-0144-3164

Appendix A: Occupational Exposure Limits and Health Effects

In evaluating the hazards posed by workplace exposures, NIOSH investigators use both mandatory (legally 

enforceable) and recommended OELs for chemical, physical, and biological agents as a guide for making 

recommendations. OELs have been developed by federal agencies and safety and health organizations to prevent 

the occurrence of 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 from adverse health effects even 

if their exposures are maintained below these levels. A small percentage may experience adverse health effects 

because of individual susceptibility, a preexisting medical condition, and/or hypersensitivity (allergy). In addition, 

some hazardous substances may act in combination with other workplace exposures, the general environment, 

or with medications or personal habits of the employee to produce adverse health effects even if the occupational 

exposures are controlled at the level set by the exposure limit. Also, some substances can be absorbed by direct 

contact with the skin and mucous membranes in addition to being inhaled, which contributes to the individual’s 

overall exposure.

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, while others are recommendations. 

The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general industry]; 29 CFR 1926 [construction 

industry]; and 29 CFR 1917 [maritime industry]) are legal limits 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 available on a given hazard and the adequacy of methods to identify and 

control the hazard. NIOSH RELs can be found in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 2010]. 

NIOSH also recommends different types of risk management practices (e.g., engineering controls, safe work 

practices, employee education/training, personal protective equipment, and exposure and medical monitoring) 

to minimize the risk of exposure and adverse health effects from these hazards. Other OELs that are commonly 

used and cited in the United States include the TLVs recommended by ACGIH, a professional organization, and 

the WEELs recommended by the American Industrial Hygiene Association, another professional organization. 

The TLVs and WEELs are developed by committee members of these associations from a review of the published, 

peer-reviewed literature. They are not consensus standards. ACGIH TLVs 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 2011]. WEELs have been established for some chemicals “when no other legal or authoritative 

limits exist” [AIHA 2011].

Outside the United States, OELs have been established by various agencies and organizations and include both 

legal and recommended limits. The Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung 

(IFA, 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/en/gestis/limit_values/index.jsp, contains 

international limits for over 1,500 hazardous substances and is updated periodically.

Employers should understand that not all hazardous chemicals have specific OSHA PELs, and for some agents 

the legally enforceable and recommended limits may not reflect current health-based information. However, an 

employer is still required by OSHA to protect its employees from hazards even in the absence of a specific OSHA 
Health Hazard Evaluation Report 2010-0144-3164 Page 25

Appendix A: Occupational Exposure Limits and Health Effects

 (continued)

PEL. 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))]. Thus, NIOSH investigators encourage employers to make use of other OELs when 

making risk assessments and risk management decisions to best protect the health of their employees. NIOSH 

investigators also encourage the use of the traditional hierarchy of controls approach to eliminate or minimize 

identified 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) personal protective equipment (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 that focuses resources on exposure controls by describing how a risk needs 

to 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 

the OELs, when available.

Below we provide the OELs and surface contamination limits for the compounds we measured.

Metalworking Fluid

NIOSH recommends limiting exposures to MWF aerosols to 0.4 mg/m3 for the thoracic particulate mass, as a 

TWA concentration for up to 10 hours per day during a 40-hour workweek [NIOSH 1998]. The NIOSH REL is 

intended to prevent or greatly reduce respiratory disorders associated with MWF exposure. Some employees have 

developed work-related asthma, HP, or other adverse respiratory effects when exposed to MWFs concentrations 

below the NIOSH REL. Limiting exposure to MWF aerosols is also prudent because certain MWF exposures have 

been associated with various cancers. In addition, limiting dermal (skin) exposure is critical to preventing allergic 

and irritant disorders related to MWF exposure. In most metalworking operations, it is technologically feasible to 

limit MWF aerosol exposures to 0.4 mg/m3 or less. Medical monitoring is needed for the early identification of 

employees who develop symptoms of MWF-related conditions such as HP, asthma, and dermatitis.

Microbial Contaminants

Insufficient data exist to determine what constitutes a safe level of microbial contamination in MWF – either in 

terms of species present, absolute number of colony forming units, or microbial components, such as endotoxin. 

The Health and Safety Executive has suggested that well-maintained MWFs should have bacterial concentrations 

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

control; control measures should be reviewed control and lower bacteria. Concentrations greater than 106 CFU/

mL indicate poor control, and immediate action should take place, including draining and cleaning the system 

if necessary [HSE 2006]. At this time there is insufficient health data to recommend a specific limit for fungal 

contamination in MWF.
Page 26 Health Hazard Evaluation Report 2010-0144-3164

Appendix A: Occupational Exposure Limits and Health Effects

 (continued)

Rylander and Jacobs have suggested an occupational threshold concentration equivalent to 100 EU/m3 of air to 

prevent airway inflammation [Rylander and Jacobs 1997]. No accepted occupational exposure limits have been 

developed in the United States because of the variability of sampling and analytical methods, and because of a lack 

of data showing a consistent dose-response relationship. In 2010, the Dutch Expert Committee on Occupational 

Safety recommended a health-based occupational exposure limit for airborne endotoxin of 90 EU/m3 as an 

8-hour TWA [DECOS 2010].

References

ACGIH [2011]. 2011 TLVs® and BEIs®: threshold limit values for chemical substances and physical agents and 

biological exposure indices. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

AIHA [2011]. AIHA 2011 emergency response planning guidelines (ERPG) & workplace environmental exposure 

levels (WEEL) handbook. Fairfax, VA: American Industrial Hygiene Association.

CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, Office of the Federal 

Register.

DECOS [2010]. Endotoxins: health-based recommended occupational exposure limit. The Hague: Health 

Council of the Netherlands, Dutch Expert Committee on Occupational Safety. [http://www.gezondheidsraad.nl/

sites/default/files/201004OSH.pdf]. Date accessed: April 2012.

HSE (Health and Safety Executive) [2006]. Bacterial contamination. [http://www.hse.gov.uk/metalworking/

bacterial.htm]. Date accessed: April 2012.

NIOSH [1998]. Criteria for a recommended standard: Occupational exposure to metalworking fluids. Cincinnati, 

OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 98-102.

NIOSH [2010]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and 

Health, DHHS (NIOSH) Publication No. 2010-168c. [http://www.cdc.gov/niosh/npg/]. Date accessed: April 

2012.

Rylander R, Jacobs RR [1997]. Endotoxin in the environment. Intl J Occup Environ Health 3(1):S1–S31. 
Health Hazard Evaluation Report 2010-0144-3164 Page 27

Appendix B: Methods 

Metalworking Fluid 

Air samples for MWFs were collected using 37-mm closed-faced three-piece cassettes containing a tared 

2-μm pore-size polytetrafluoroethylene filter and the supporting pad. The sampling train consisted of the 

37-mm cassette, a BGI thoracic cyclone, and Tygon® tubing connecting the sampling assembly to SKC Air 

Check® 2000 air sampling pumps. A sampling rate of 1.6 Lpm was used to collect the thoracic fraction 

of the aerosol. Each pump was calibrated before and after use. The sampling media was attached to the 

employee’s lapel within the breathing zone (breathing zone is defined as an area in front of the shoulders 

with a radius of 6 to 9 inches). The samples were analyzed by gravimetric analysis for the thoracic fraction 

of MWF particulates per NIOSH Method 5524 [NIOSH 2012]. After the filter was gravimetrically 

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

Method 5524.

Endotoxin

Air samples were collected using an endotoxin-free three-piece 37-mm closed-face cassette, preloaded 

with 0.45 μm pore-size polycarbonate filters. Samples were collected with AirCheck2000® personal air 

sampling pumps calibrated at 2 Lpm. Each pump was calibrated before and after use. Endotoxin analysis 

was performed by a contract laboratory. Samples were analyzed for endotoxin content with the kineticchromogenic procedure using the limulus amebocyte lysate assay [Cambrex 2005]. For these analyses, one 

EU was equivalent to 0.053 nanograms of endotoxin. The limit of detection was 0.025 EU per sample.

Microbial Sampling 

Bulk samples of MWFs were collected by filling 1-liter sterile bottles leaving at least 2 inches of headspace. 

These samples were kept at ambient room temperature and shipped within 2 days to the laboratory for 

analysis. Each sample was concentrated by a 30-minute centrifuge, and excess fluid was poured off. The 

concentrate was vortexed for 1 minute and then plated to the appropriate media.

For aerobic bacteria, the media consisted of tryptic soy agar with polysorbate 80 and lecithin and BCYE. 

Plates were incubated at 23°C ± 2°C for 5 to 7 days and read daily. The media for fungi was yeast malt 

extract, inhibitory mold agar with gentamicin and chloramphenicol, and BCYE. Plates were incubated at 

23°C ± 2°C for 10 days as needed. Plates were read on day 3 to see if it was overgrown, and on days 5 or 7 

and day 10.

The media for mycobacteria consisted of BCYE, Middlebrook 7H10, and Mitchison 7H11S. Plates and 

broth were incubated at 32°C ± 2°C in 7%–10% CO2 for 4 weeks. Cultures were read at 3 to 5 days and 

7 days. If specimens were overgrown, additional dilutions were made. A Ziehl-Neelsen stain of broths was 

performed at 2–3 weeks and 4 weeks [MSI 2011].
Page 28 Health Hazard Evaluation Report 2010-0144-3164

Appendix B: Methods

 (Continued) 

Questionnaire

We recruited employees (exposed) in the aircraft manufacturing building who worked with MWFs and 

employees in an adjacent building without MWF use (unexposed). Participating employees filled out 

a questionnaire about demographics, work practices and location, smoking status, and dermal and 

respiratory symptoms.

The dermatologic questions include questions modified from the Nordic Occupational Skin 

Questionnaire [Susitaival et al. 2003]. Three questions from the Nordic Occupational Skin Questionnaire 

were used to determine if participants were atopic (prone to allergic diseases such as asthma, eczema, 

and allergic rhinitis). A validated question about having an itchy rash that comes and goes for at least six 

months and has at some time affected skin creases was used to determine a history of atopic dermatitis 

or eczema [Williams et al. 1994]. A question asking if the participant had ever had hay fever or other 

symptoms of nasal allergy was used to determine a history of allergic rhinitis. Finally, each participant 

was asked if he or she had ever had asthma. A participant with a positive answer to any of these three 

questions was considered atopic.

The respiratory questions include validated questions on asthma symptoms from the European 

Community Respiratory Health Survey [Grassi et al. 2003]. The questions are: (1) Have you been woken 

up with a feeling of tightness in your chest at any time in the last 12 months?; (2) Have you had an attack 

of asthma in the last 12 months?; (3) Are you currently taking any medicine (including inhalers or pumps, 

aerosols, or tablets) for asthma?; and (4) Have you had wheezing or whistling in your chest at any time in 

the last 12 months? If participants answered yes to (4) they were asked (a) Have you been at all breathless 

when the wheezing or whistling noise was present? and (b) Have you had this wheezing or whistling when 

you did not have a cold? A positive response on any of these questions on the survey has a sensitivity 

of 75% and a specificity of 80% for asthma symptoms on the basis of a clinical examination with 

immunoglobulin E testing against common allergens, spirometry, and methacholine challenge testing. 

We modified these questions by adding the following, “or since beginning your current position if in that 

position less than 12 months,” because some participants had not been in their current position for 12 

months. In addition, we added questions about changes in symptoms or medication used on days off work 

or on vacation. If participants responded that symptoms improved on days off work or on vacation, or that 

medication use was less frequent on days off or on vacation, then their symptoms were classified as workrelated. Finally, if a participant responded positively to any of these questions, he or she was classified as 

having asthma symptoms.

A question regarding problems with sneezing, runny nose, or blocked nose in the last 12 months probes 

work-related rhinoconjunctivitis and was adapted from the International Study of Asthma and Allergies in 

Childhood [Asher et al. 1995]. If participants responded that symptoms improved on days off work or on 

vacation, then their symptoms were classified as work related. A question regarding more than one episode 

of illness in the last 12 months with at least two of the following symptoms: cough, wheeze, shortness of 

breath, or chest tightness was based on diagnostic criteria for HP identified in two prior studies [Fox et al. 

1999; Lacasse et al. 2003]. If participants responded positively to this question, they were asked if they had 
Health Hazard Evaluation Report 2010-0144-3164 Page 29

Appendix B: Methods

 (Continued) 

fever or weight loss with these episodes. If they answered yes, they were classified as having symptoms of 

HP. Participants were also asked if they had pneumonia or chest flu in the last 12 months, and if yes, how 

many times. This was asked because HP is often misdiagnosed as pneumonia or chest flu. We compared 

the number of times these illnesses were reported between exposed and unexposed participants. 

Workplace information on the questionnaire was used to classify exposure. Participants were defined 

as exposed to MWFs if they usually worked with MWF in their current job. Other information in the 

questionnaire included LEV controls, type of MWF supply, PPE use, and hand hygiene questions.

Statistical Analysis

All data were analyzed using SAS 9.2 (SAS Institute Inc., Cary, North Carolina). Data were analyzed by 

age, sex, smoking status, hours worked per week, work area, and job title. The log binomial regression, 

Poisson regression, and the Cox proportional hazards model have been recommended to estimate PR 

[Barros and Hirakata 2003]. The log binomial model directly models the prevalence ratio when the 

variable is dichotomous [Skov et al. 1998] and was used to estimate PR with 95% CI for dermal and 

respiratory outcomes in this study. Fitted models for dermal and respiratory outcomes included exposure 

variables that had greater than 10% change in the PR when included in the model. Chi square or Fisher’s 

exact tests were calculated to determine if there was an association between exposure to MWFs and dermal 

and respiratory symptoms. The chi square or Fisher’s exact tests were used because dichotomous outcomes 

were compared across 2 groups (exposed and unexposed). The Fisher’s exact test was used for sparse data. 

A P value equal to or less than 0.05 was considered significant. A 95% CI that does not include one was 

considered significant.

References

Asher MI, Keil U, Anderson HR, Beasley R, Crane J, Martinez F, Mitchell EA, Pearce N, Sibbald B, 

Stewart AW, Strachan D, Weiland SK, Williams HC [1995]. International Study of Asthma and Allergies 

in Childhood (ISAAC): rationale and methods. Eur Respir J 8(3):483–491.

Barros AJ, Hirakata VN [2003]. Alternatives for logistic regression in cross-sectional studies: an empirical 

comparison of models that directly estimate the prevalence ratio. BMC Med Res Methodol 3(1):21.

Cambrex [2005]. Limulus Amebocyte Lysate (LAL), Kinetic-QCL. Catalog Number: 50-650U. Walkersville, 

MD.

Fox J, Anderson H, Moen T, Gruetzmacher G, Hanrahan L, Fink J [1999]. Metal working fluid-associated 

hypersensitivity pneumonitis: an outbreak investigation and case-control study. Am J Ind Med 35(1):58–

67.
Page 30 Health Hazard Evaluation Report 2010-0144-3164

Appendix B: Methods

 (Continued) 

Grassi M, Rezzani C, Biino G, Marinoni A. [2003] Asthma-like symptoms assessment through ECRHS 

screening questionnaire scoring. J Clin Epidemiol 56(3):238–247.

Lacasse Y, Selman M, Costabel U, Dalphin J, Ando M, Morell F, Erkinjuntti-Pekann R, Muller N, Colby 

TV, Schuyler M, Cormier Y [2003]. Clinical diagnosis of hypersensitivity pneumonitis. Am J Respir Crit 

Care Med 168(8):952–958.

MSI [2011]. Microbial analysis – metalworking fluids, Standard operating procedures. Environmental 

Manual II: SS030.01. Microbiology Specialists, Inc. Houston, TX.

NIOSH [2012]. NIOSH manual of analytical methods (NMAM®), 4th ed. Schlecht PC, O’Connor PF, 

eds. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

94–113 (August 1994); 1st Supplement Publication 96–135, 2nd Supplement Publication 98–119; 3rd 

Supplement 2003–154. [http://www.cdc.gov/niosh/docs/2003-154/]. Date accessed: April 2012.

Skov T, Deddens J, Petersen MR, Endahl L [1998]. Prevalence proportion ratios: estimation and 

hypothesis testing. Int J Epidemiol 27(1):91–95.

Susitaival P, Flyvholm MA, Meding B, Kanerva L, Lindberg M, Svensson A, Olafsson JH [2003]. Nordic 

Occupational Skin Questionnaire (NOSQ-2002): a new tool for surveying occupational skin diseases and 

exposure. Contact Dermatitis 49(2):70–76.

Williams HC, Burney PG, Pembroke AC, Hay RJ [1994]. The U.K. Working Party’s diagnostic criteria for 

atopic dermatitis. I. Derivation of a minimum set of discriminators for atopic dermatitis. Br J Dermatol 

131(3):383–396.
Health Hazard Evaluation Report 2010-0144-3164 Page 31

Appendix C: Tables

Table C1. Production cell machine operators’ PBZ air sampling results, engineering control use, and cutting type 

from May 5–6, 2011

Machine Time Volume

Thoracic 

Particulate Extracted MWF Enclosure Mist Cutting

Type (minutes) (m3) Concentration (mg/m3) Collector Type

Drill 438 0.708 0.11 ND* None No Carbide

Grinder 400 0.650 0.17 ND Full Yes NA†

Grinder 304 0.492 0.16 ND Partial Yes NA

Grinder 407 0.657 0.13 ND Partial Yes NA

Mill 380 0.611 0.29 [0.31]‡ Full Yes Carbide

Mill 426 0.680 0.28 ND None No NA

Mill 431 0.696 0.11 ND Full No Carbide

Mill 227 0.367 [0.13] ND Partial No Carbide

Mill 376 0.607 [0.10] [0.16] Partial No Carbide

Mill 425 0.699 [0.10] ND Full No Carbide

Mill drill 365 0.593 [0.06] ND None No Carbide

Mill drill 399 0.646 0.12 [0.15] Partial No Carbide

Omni mill 370 0.601 0.13 ND Partial No Carbide

Omni mill 385 0.617 [0.11] ND None No Carbide

Omni mill 401 0.645 [0.09] ND Partial No Carbide

Omni mill 401 0.653 [0.07] ND Partial No Carbide

Omni mill 319 0.519 [0.05] ND Partial No Carbide

Turning 367 0.595 0.20 ND Partial Yes Carbide

Turning 379 0.613 0.14 ND Partial§ Yes, but off Carbide

Turning 421 0.689 0.14 ND Full Yes Ceramic

Turning 398 0.637 [0.09] ND Full Yes Carbide

Turning 400 0.639 [0.09] ND Partial Yes Carbide

Turning 381 0.621 [0.08] ND Full Yes Carbide

Turning 361 0.584 [0.07] [0.19] Partial Yes, but off Both¶

Turning 444 0.688 [0.06] ND Partial Yes Both

Turning 441 0.712 [0.05] ND Partial No Carbide

Turning 419 0.676 [0.04] ND Partial Yes Both

VTL 379 0.615 0.21 ND Full Yes Both

VTL 426 0.687 0.14 ND Partial Yes Both

VTL 390 0.626 0.14 ND Partial Yes Ceramic

VTL 392 0.635 0.12 ND None No Carbide

VTL 411 0.668 0.12 ND Full Unknown Ceramic

VTL 434 0.696 0.11 ND Full Yes Both

VTL 333 0.538 [0.11] ND Full Yes Both

VTL 415 0.649 [0.11] ND None No Carbide

VTL 416 0.675 [0.10] ND Partial Yes Carbide

VTL 421 0.683 [0.09] ND Partial Yes Carbide

VTL 412 0.661 [0.09] ND Partial Yes Both
Page 32 Health Hazard Evaluation Report 2010-0144-3164

Appendix C: Tables

 (continued)

Machine Time Volume

Thoracic 

Particulate Extracted MWF Enclosure Mist Cutting

Type (minutes) (m3) Concentration (mg/m3) Collector Type

VTL 237 0.385 [0.07] ND Partial Yes, but off Carbide

VTL 247 0.399 [0.07] ND Partial Yes Carbide

VTL 427 0.685 [0.07] ND Partial Yes Carbide

VTL 411 0.666 [0.07] ND Partial No Carbide

VTL 427 0.695 [0.04] ND None No Carbide

Hot oil 

flush 437 0.705 0.12 ND NA NA NA

Hot oil 

flush 298 0.484 [0.08] ND NA NA NA

Standalone 

machine

388 0.620 0.13 ND None Yes NA

NIOSH REL (10-hour TWA) 0.4 None

OSHA PEL None None

ACGIH TLV None None

MDC** (mg/m3) 0.03 0.14

MQC** (mg/m3) 0.12 0.50

*ND – not detected

†NA – not applicable

‡Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more 

uncertainty associated with these values than with concentrations above the MQC.

§Observed that enclosure was left open when machine was operating

¶Both carbide and ceramic cutting

**Based on an average air volume of 0.625 m3

Table C1. Production cell machine operators’ PBZ air sampling results, engineering control use, and cutting type 

from May 5–6, 2011 (continued)
Health Hazard Evaluation Report 2010-0144-3164 Page 33

Appendix C: Tables

 (continued)

Table C2. Area air sampling results for MWFs on May 5–6, 2011

Day 1 Day 2

Time Volume Concentration (mg/m3) Time Volume Concentration (mg/m3)

Location (minutes) (m3)

Thoracic 

Particulate

Extracted 

MWF (minutes) (m3)

Thoracic 

Particulate

Extracted 

MWF

Large parts 468 0.755 0.17 [0.17]* 417 0.676 0.12 ND†

North central 

system 432 0.692 0.13 ND 416 0.661 0.13 ND

Milling 376 0.607 0.13 ND 430 0.695 0.24 [0.22] 

Mill drill NA‡ NA NA NA 348 0.565 0.16 ND

Building 800 271 NA§ NA§ NA§ 346 0.564 [0.07] ND

MDC¶ (mg/m3) 0.03 0.14 0.03 0.14

MQC¶ (mg/m3) 0.12 0.50 0.12 0.50

*Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty 

associated with these values than with concentrations above the MQC. 

†ND – not detected

‡NA – not applicable

§Missing information

¶Based on an average air volume of 0.625 m3
Page 34 Health Hazard Evaluation Report 2010-0144-3164

Appendix C: Tables

 (continued)

Table C3. Area endotoxin air sampling results on May 5–6, 2011

Time Volume Concentration

Location (minutes) (m3) (EU/m3)

Mill 376 0.745 2.7

VTL 382 0.76 2.6

Hot oil flush 198 0.40 1.9

North Central System 431 0.86 1.7

VTL 375 0.74 1.5

Omni mill 385 0.76 1.6

VTL 194 0.39 1.4

Turning machine 371 0.74 1.3

Mill 320 0.63 0.85

Turning machine 318 0.63 0.83

VTL 315 0.63 0.69

Turning machine 304 0.47 0.61

VTL 375 0.74 0.55

VTL 298 0.59 0.48

VTL 318 0.63 0.46

Drill mill 364 0.73 0.45

Grinder 319 0.64 0.42

Mean 1.18

Meeting room sample 1 176 0.53 0.23

Meeting room sample 2 244 0.80 0.24
Health Hazard Evaluation Report 2010-0144-3164 Page 35

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

● Utilizing 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.

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]. Gloves may occlude irritants or allergens next to the skin, 

and PPE components may directly irritate the skin, so the correct use of PPE is at least as important as the 

correct selection of materials [Kwon et al. 2006].

Similarly, the excessive pursuit of personal hygiene in the workplace may actually lead to misuse of 

soaps and detergents and cause irritant contact dermatitis. Proper hand washing methods and adequate 

moisturizing are valuable in preventing contact dermatitis [Warshaw et al. 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 [Schwanitz et al. 2003; Loffler et al. 2006; 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.

Appendix D: Tips on preventing dermatitis
Page 36 Health Hazard Evaluation Report 2010-0144-3164

Appendix D: Tips on preventing dermatitis

 (continued)

The following 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.

References

Chew AI, Maibach HI [2003]. Occupational issues of irritant contact dermatitis. Int Arch Occup Environ 

Health 76(5):339–346.

Foo CC, Goon AT, Leow YH, Goh CL [2006]. Adverse skin reactions to personal protective equipment 

against severe acute respiratory sundrome-a descriptive study in Singapore. Contact Dermatitis 55(5):291–294.

Kwon S, Campbell LS, Zirwas MJ [2006]. Role of protective gloves in the causation and treatment of 

occupational irritant contact dermatitis. J Am Acad Dermatol 55(5):891–896.

Loffler H, Bruckner T, Diepgen T, Effendy I [2006]. Primary prevention in health care employees: a 

prospective intervention study with a 3-year training period. Contact Dermatitis 54(4):202–209.

NIOSH [1988]. Proposed national strategy for the prevention of leading work-related diseases and injuries: 

Dermatological conditions. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH), 

Publication No. 89-136.

Schwanitz HJ, Riel U, Schlesinger T, Bock M, Skudlik C, Wulfhorst B [2003]. Skin care management: 

educational aspects. Int Arch Occup Environ Health 76(5):374–381.

Warshaw E, Lee G, Storrs FJ [2003]. Hand dermatitis: a review of clinical features, therapeutic options and 

long-term outcomes. Am J Contact Dermat 14(3):119–137.

Weisshaer E, Radulescu M, Bock M, Albrecht U, Diepgen TL [2006]. Educational and dermatological 

aspects of secondary individual prevention in healthcare workers. Contact Dermatitis 54(5):254–260.
Health Hazard Evaluation Report 2010-0144-3164 Page 37

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Health Hazard Evaluation Report 2010-0144-3164 Page 39

Acknowledgments and

Availability of Report

The Hazard Evaluations and Technical Assistance Branch (HETAB) of the National Institute for 

Occupational Safety and Health (NIOSH) conducts field investigations of possible health hazards in the 

workplace. These investigations are conducted under the authority of Section 20(a)(6) of the Occupational 

Safety and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary of Health and Human 

Services, following a written request from any employer or authorized representative of employees, to 

determine whether any substance normally found in the place of employment has potentially toxic effects 

in such concentrations as used or found. HETAB also provides, upon request, technical and consultative 

assistance to federal, state, and local agencies; labor; industry; and other groups or individuals to control 

occupational health hazards and to prevent related trauma and disease.

Mention of any company or product does not constitute endorsement by NIOSH. In addition, citations 

to websites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or 

their programs or products. Furthermore, NIOSH is not responsible for the content of these websites. All 

Web addresses referenced in this document were accessible as of the publication date.

This report was prepared by Lilia Chen and Francisco Meza of HETAB, and Naomi Hudson of Surveillance 

Branch, Division of Surveillance, Hazard Evaluations and Field Studies. Industrial hygiene field assistance 

was provided by Diana Ceballos, James Couch, Matthew Dahm, and Todd Niemeier. Industrial hygiene 

equipment and logistical support were provided by Donald Booher and Karl Feldmann. Medical field 

assistance was provided by Carlos Aristeguieta, Marie De Perio, Chad Dowell, Judith Eisenberg, Stefanie 

Evans, Kemka Hekerem, Melody Kawamoto, Charles Mueller, Elena Page, Robert McCleery, Alysha 

Meyers, Jessica Ramsey, Loren Tapp, Allison Tepper, and Douglas Wiegand. Statistical analysis was 

provided by Naomi Hudson. Analytical support was provided by Bureau Veritas North America (Novi, 

Michigan), Microbiology Specialists Incorporated (Houston, Texas), and EMLab P&K (Cherry Hill, New 

Jersey). Health communication assistance was provided by Stefanie Evans. Editorial assistance was provided 

by Ellen Galloway. Desktop publishing was performed by Greg Hartle and Mary Winfree.

Copies of this report have been sent to employee and management representatives, the state health 

department, and the Occupational Safety and Health Administration Regional Office. This report is not 

copyrighted and may be freely reproduced. The report may be viewed and printed at http://www.cdc.gov/

niosh/hhe/. Copies may be purchased from the National Technical Information Service at 5825 Port 

Royal Road, Springfield, Virginia 22161.
Below is a recommended citation for this report:

NIOSH [2012]. Health hazard evaluation report: metalworking fluid exposure at 

an aircraft engine manufacturing facility – Ohio. By Chen L, Meza F, Hudson N. 

Cincinnati, OH: U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and 

Health, NIOSH HETA No. 2010-0144-3164.

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