Health Hazard Evaluation Report 2013-0033-3238 Page 1

Evaluation of Skin and Respiratory Symptoms 

among Employees with Exposure to Metals, 

Metalworking Fluids, and Noise at an Orthopedic 

Implant Manufacturer

HHE Report No. 2013-0033-3238

July 2015

Catherine Beaucham, MPH, CIH

Loren Tapp, MD, MS

Charles Mueller, MS

Aalok Y. Oza, MPH

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 2013-0033-3238

Contents

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

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

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

Background ..........................................1

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

Results .................................................. 7

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

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

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

Appendix B ........................................ 28

References ......................................... 34

Acknowledgements .......................... 39

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 2013-0033-3238 Page i

We assessed exposure to 

metals, metalworking fluids, and 

noise at an orthopedic implant 

manufacturer. We measured an 

overexposure to cobalt before 

local exhaust ventilation system 

improvements were made. We 

also measured overexposures 

to noise. One air sample for 

hexavalent chromium was 

more than half the NIOSH REL. 

Working as a femoral finisher 

was associated with having 

nasal and skin symptoms, 

suggesting symptoms could be 

related to cobalt dust exposure. 

We recommended improving 

engineering controls, starting a 

hearing conservation program, 

improving employee training, 

and doing medical evaluations 

for employees with persistent 

work-related symptoms.

Highlights of this Evaluation 

The Health Hazard Evaluation Program received a confidential request from employees 

who were concerned about exposures to mold, metalworking fluid mists, and metals at an 

orthopedic implant manufacturer. Our evaluation was in one building (building 2402) that 

manufactured cobalt chromium femoral implants, titanium femoral stem implants, and plastic 

patellar implants.

What We Did

● We looked at employee work practices.

● We tested the air and work surfaces for metals.

● We tested the air for metalworking fluid mist.

● We reviewed company records on air tests and 

written policies and procedures.

● We asked employees about their health and 

work-related symptoms using interviews 

and questionnaires.

● We collected urine from employees to check 

their cobalt and chromium levels.

● We measured noise levels.

What We Found

● One air cobalt level in the finishing area was 

above the most protective exposure limit.

● Cobalt and chromium levels in employee urine 

samples were low.

● Working as a femoral finisher was 

associated with having nasal and skin 

symptoms. These symptoms could be related 

to cobalt dust exposure.

● Femoral finishers doing box polishing 

had exposure to low levels of hexavalent 

chromium, a known carcinogen.

● Some surfaces in the break room were 

contaminated with cobalt, chromium, and aluminum.

● Some noise exposures were above the limits set by the Occupational Safety and Health 

Administration and most noise exposures by the polishing and buffing stations and 

in the nitric passivation room were above the limits set by the National Institute for 

Occupational Safety and Health. 
Page ii Health Hazard Evaluation Report 2013-0033-3238

What the Employer Can Do

● Implement better engineering controls (for protection from metals and noise exposures) 

and a hearing conservation program.

● Train employees to recognize work hazards and prevent exposures.

● Stop employees from using compressed air to clean work clothing.

● Measure finishing department employee exposures to hexavalent chromium to find out 

if new exposure controls or medical monitoring is needed.

● Encourage employees to report potential work-related health conditions to their 

supervisor. Employees with persistent symptoms should be evaluated by an 

occupational medicine physician.

● Stop using latex gloves because of the potential for allergic reactions to latex.

● Require nitrile glove use when skin contact with metalworking fluids or metal dust 

is possible. 

What Employees Can Do

● Stop using compressed air to clean work clothing.

● Remove gloves and wash hands when leaving the production area. 

● Report symptoms and health concerns to your supervisor.

● Inform your doctor about your exposure to chromium and cobalt metals.

● Wear nitrile gloves when skin contact with metalworking fluids or metal dust is possible.

● Use hearing protection when working at the polishing and buffing stations and in the 

nitric passivation room.
Health Hazard Evaluation Report 2013-0033-3238 Page iii

Abbreviations

μg Micrograms

μg/100 cm2 Micrograms per 100 squared centimeters

μg/L Micrograms per liter

μg/m3 Micrograms per cubic meter

ACGIH® American Conference of Governmental Industrial Hygienists

AL Action level

BEI® Biological exposure index

CFR Code of Federal Regulations

dBA Decibels, A-scale

Hz Hertz

MWF Metalworking fluid

MDC Minimum detectable concentration

MQC Minimum quantifiable concentration

ND Not detected

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PEL Permissible exposure limit

REL Recommended exposure limit

STEL Short-term exposure limit

TLV® Threshold limit value

TWA Time-weighted average

WEELTM Workplace environmental exposure level
Page iv Health Hazard Evaluation Report 2013-0033-3238

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Health Hazard Evaluation Report 2013-0033-3238 Page 1

Introduction

The Health Hazard Evaluation Program received a confidential request from employees 

at an orthopedic implant manufacturer. The request concerned exposures associated with 

machining of cobalt-chromium and titanium stem femoral implants, and mold from a water 

leak in the employee break area. Employees were concerned that these exposures were 

causing respiratory problems. We visited the facility in February and June 2013. We sent 

letters to the employer and employees with initial findings and recommendations in March 

and August 2013. 

Background

The company began operations in the 1980s, manufacturing orthopedic joint-replacement 

products and surgical instruments for use in hip, knee, shoulder, and other orthopedic surgical 

procedures. At the time of our evaluation, the company had nine buildings and operated 5 or 

6 days a week, with two 8-hour shifts per day. Approximately 400 employees worked for the 

company. Twenty-six employees (all non-union) worked in the building of concern (building 

2402), where plastic patellas (knee caps), cobalt-chromium femoral implants (used for knee 

joint replacement), and titanium stem femoral implants (used for hip joint replacement) 

were manufactured. All employees were required to wear safety glasses and steel-toe boots; 

company-issued coveralls, earplugs, protective gloves, and respirator use were optional and 

varied by department.

In fall 2012, an anonymous complaint to the Occupational Safety and Health Administration 

(OSHA) resulted in a visit by a state consultation program working in cooperation with the 

OSHA Safety and Health Achievement Recognition Program. The complaint concerned 

employee exposures to mold in the employee break room and to oil mist in the production 

area of the building we later evaluated. In October 2012, a consultant collected personal 

and area air samples for oil mist and dust. The concentrations of oil mist and total dust were 

below the OSHA permissible exposure limits (PELs). The consultant did not analyze the dust 

samples for metals. Mold was discovered in the break room. The break room was closed, and 

remediation was performed prior to our first visit.

Process Description

Plastic Implants

The facility produced plastic prosthetic patellas by slicing polyethylene rods with an electric 

chain-driven saw. The employees used a handheld burr grinder to remove irregularities in the 

polyethylene slices. A local exhaust ventilation hose attached to a vacuum pump removed 

dust. The employees processed the slices in a mill and then a lathe to shape the plastic slices 

into prosthetic patellas. The plastic implant mill used one type of water-soluble metalworking 

fluid (MWF). Employees wore latex gloves. Some employees wore an N95 filtering 

facepiece respirator and earplugs, both of which were optional.
Page 2 Health Hazard Evaluation Report 2013-0033-3238

Metal Implants

Cobalt-Chromium Femoral Implants

The employees in the building of concern machined and finished cobalt-chromium femoral 

implants used for prosthetic knee joints. Four enclosed grinding machines with mist 

collectors processed up to six implants at a time, depending on the model. Three employees 

worked in femoral machining and three in plastic patella machining. The facility used two 

types of MWFs for the femoral implant grinders. The Haas® grinders used Blasomill® 

10 MWF and the Walter® grinder used Sintogrind® TTS. A third type of MWF, Blasocut 

2000, was used in the plastic patellar implant lathe. No biocides were added to the MWFs. 

After a machining cycle was complete, machinists manually removed the implants, wiped 

off excess MWF with a paper towel, and washed the implants in an open basin containing an 

alkaline cleaning solution. The machinists did not wear gloves when handling the implants. 

After cleaning, machinists transferred the implants to the finishing department where eleven 

employees worked femoral finishing. Femoral finishing tasks included coarse polishing, box 

polishing, buffing, drag finishing, “mask and blast,” and “trim and blast.” Femoral finishing 

employees first removed irregularities using a large belt sander at the coarse polishing station, 

then transferred the implants to the box polishing station (Figure 1). At this station, finishers 

used a small belt sander with a thin abrasive strip to polish the sharper angles and bends on 

the implants. Some employees wore an N95 filtering facepiece respirator and earplugs.

Figure 1. Box polish station. Photo by NIOSH.

The coarse polishing station and box polishing station generated dusts that could contain 

cobalt and chromium. Femoral finishing employees may also be exposed to hexavalent 

chromium in this setting when polishing cobalt-chromium parts because “hot work” such 

as grinding on chromium sometimes generates hexavalent chromium [OSHA 2015]. When 

polishing and buffing, employees wore cut-resistant, palm-coated gloves; safety glasses; and 

steel toe boots. Some employees wore an N95 filtering facepiece respirator, company-issued 

coveralls, and earplugs.
Health Hazard Evaluation Report 2013-0033-3238 Page 3

Following box polishing, the implants were polished in a large tumbler filled with a ceramic 

abrasive, a process called drag finishing. Then finishing employees used a cloth wheel and 

buffing compound at one of the finishing stations to remove scratches and abrasions from 

the surface of the femoral implant. This buffing compound contained aluminum oxide. Some 

employees wore an N95 filtering facepiece respirator, company-issued coveralls, and earplugs.

Finishing employees then cleaned the parts, dipped them with a gloved hand into a 350°F 

molten plastic sealant, and sandblasted the exposed surface of the implant in an enclosed 

cabinet. This task was called mask and blast. The finishers carefully inspected each part for 

imperfections and removed the part with a hand-held tool. This task was called trim and 

blast. The implants were transferred to the passivation room where they were cleaned with 

methyl ethyl ketone by two employees wearing gloves and then dipped into a nitric acid 

passivation tank to prevent corrosion. These employees wore latex gloves, steel toe boots, 

safety glasses, and a disposable apron. Some employees wore an N95 filtering facepiece 

respirator and earplugs.

Titanium Stem Implants

The titanium femoral stems used in prosthetic hip joints were also finished in this building. 

Two employees (titanium stem finishers) polished the stems with a belt sander and then 

transferred them to a tumbler/polisher filled with ceramic, plastic, or corncob abrasive polishing 

media. Employees sandblasted the stem heads inside of a glove box-type enclosure to create 

a coarse surface to permit bone attachment. Employees then transferred finished parts to the 

passivation room for a dip into the nitric acid passivation process described above. 

Methods

We had the following four objectives for this evaluation:

1. Assess work-related health concerns of employees

2. Evaluate employees’ exposures to mold, dusts, MWFs, and metals 

3. Qualitatively evaluate the effectiveness of the local exhaust ventilation systems

4. Assess noise exposures associated with different jobs

In February 2013, we met with employer and employee representatives to discuss the health 

hazard evaluation request and evaluate the building of concern. During this initial visit, 

we walked through the building to become familiar with the layout and to observe work 

processes, practices, and conditions. We held confidential medical interviews, reviewed 

reports and records, collected air and surface samples to analyze for dust, metals, and MWF; 

measured sound levels; and examined the break room area for mold growth and moisture. We 

performed a follow-up visit in June 2013 to further evaluate metal and noise exposures. We 

also administered a health questionnaire to employees, collected employee urine samples to 

analyze for metals, and examined changes implemented between the two visits. Information 

on health effects and occupational exposure limits (OELs) for the contaminants we measured 

can be found in Appendix B.
Page 4 Health Hazard Evaluation Report 2013-0033-3238

Employee Interviews and Records Review

In February 2013, we confidentially interviewed all 26 employees working in the building 

of concern about their medical and work history, and we reviewed medical records of 

employees with health problems they thought might be work-related. We reviewed the OSHA 

Form 300 Logs of Work-Related Injuries and Illnesses and workers’ compensation claims 

from 2010 through 2012. In addition, we reviewed the facility’s safety and health program, 

hazard communication program, and respiratory protection program.

Contaminant Sampling, Ventilation Assessment, and 

Observations

In February 2013, we took personal and area air samples for total particulate, metals 

(chromium, cobalt, and titanium), and MWF over two work shifts to identify work locations 

and processes where employees had the highest potential for airborne exposure. We also 

collected personal and area air samples for hexavalent chromium to learn whether the 

manufacturing process was generating this hazardous compound from the chromium metal 

in the femoral implants. In this report, we use the term “chromium” for chromium metal 

and all compounds containing chromium (in the trivalent and hexavalent states) and use the 

term “hexavalent chromium” for chromium compounds that exist only in the hexavalent 

state which is considered a more toxic form of chromium (see Appendix B for explanation). 

We collected surface wipe samples throughout the facility to evaluate housekeeping 

effectiveness. Table 1 lists the number of samples we collected and the sampling and 

analytical methods we used. We analyzed the chromium, cobalt, and titanium in air samples 

by the National Institute for Occupational Safety and Health (NIOSH) Method 7303 [NIOSH 

2014a], with modification. The modification included wiping the interior walls of the filter 

cassette with a wet smear tab to collect particles on the inside walls. The smear tab was then 

analyzed along with the filter sample as recommended by NIOSH [2014b]. 

We observed work practices and examined the local exhaust ventilation system at the box 

polishing station and nitric passivation tank using smoke tubes to help visualize airflow. We also 

examined the newly renovated break room area for visual signs of mold growth or water damage. 

We opened all of the newly installed cabinets to look for pooled water or stains on the wood.
Health Hazard Evaluation Report 2013-0033-3238 Page 5

Table 1. Air and surface sampling and analytical methods, February 2013

Analyte Total number of 

personal samples 

collected

Total number of 

area samples 

collected

NIOSH

method

number*

Hexavalent chromium in air 4 7 7605

MWFs in air 3 7 5524

Total particulate in air 9 10 0500

Chromium, cobalt, and titanium in air† 10 Not applicable 7303

Chromium, cobalt, and titanium on surfaces Not applicable 15 9102

*[NIOSH 2014]

†Total particulate, chromium, titanium, and cobalt in air were collected on the same filter.

In June 2013, we evaluated employee exposures to aluminum, chromium, cobalt, and 

titanium in air and on surfaces. In addition, we collected and analyzed bulk samples of the 

used and unused MWF for cobalt and chromium (Table 2). We also noted changes in work 

practices and local exhaust ventilation systems.

Table 2. Air, surface, and bulk sampling and analytical methods, June 2013

Analytes Total number of 

personal samples 

collected

Total number of 

area samples 

collected

NIOSH 

method 

number*

Aluminum, chromium, cobalt, and 

titanium in air

16 Not applicable 7303†

Cobalt and chromium in bulk MWF Not applicable 4 7303‡

Aluminum, chromium, cobalt, and 

titanium on surfaces

Not applicable 11 9102

*[NIOSH 2014]

†Modified to address sampler wall losses

‡Modified for liquid matrix

Questionnaire

In June 2013, we asked all 26 employees in the building to complete a written questionnaire. 

The questionnaire asked about demographics, work and medical history, personal protective 

equipment use, and tobacco use. We asked about possible non-work exposures to cobalt 

and chromium that could affect the urinalysis results. These exposures included painting, 

staining, or glazing with cobalt- or chromium-containing pigments; taking vitamins that 

contain Vitamin B12, or cyanocobalamin, a form of cobalt; or having joint replacement 

surgery with a metal replacement joint [ACGIH 2001]. We also asked about skin, nasal, and 

respiratory symptoms and whether these symptoms changed on days off work. 

We compared symptoms of employees exposed to chromium and cobalt dust with symptoms 

of employees having minimal or no chromium and cobalt dust exposure. We also compared 

symptoms of employees exposed to MWF with symptoms of employees with minimal or 
Page 6 Health Hazard Evaluation Report 2013-0033-3238

no MWF exposure. We based the workplace exposure groups on employee job titles and 

observations. We evaluated relationships between workplace exposure groups and symptoms 

by using Fisher’s exact test. All statistical analyses were done with SAS statistical software 

version 9.3. All tests were two-tailed, and statistical significance was set at P < 0.05. We 

looked at symptoms that improved on days away from work as an indication of potential 

work-relatedness.

Biological Exposure Monitoring

We asked employees to provide an end-of-shift, end-of-workweek urine sample to analyze 

for urinary cobalt and chromium levels. We obtained their consent to participate. The 

urine analyses provided a measure of recent exposure to cobalt and chromium metals. 

We also measured creatinine in the urine to see how well the participants’ kidneys were 

functioning; if the creatinine level is too high or too low, the urine is too concentrated or 

dilute so that the cobalt and chromium results are not accurate and cannot be reported. 

Urine samples were collected in acid-washed containers, kept cold, and shipped overnight 

to the laboratory. The samples were analyzed for cobalt and chromium by inductively 

coupled plasma mass spectrometry, which is capable of detecting metals at concentrations 

as low as one part per trillion. 

We compared the cobalt and chromium urine concentration results to OELs where available 

(see Appendix B). 

Comparing Questionnaire, Contaminant Sampling, and 

Biomonitoring Data

We compared urine and air cobalt levels among employee groups based on job titles and 

exposure information reported on the questionnaire by using Wilcoxon tests. For the 

12 employees who had both types of measurements, we also compared their urine cobalt 

levels with their air cobalt levels. Four of these 12 participants had two air sample 

measurements each. We used the average of the two air measurements to obtain a single 

measurement to use in our calculations. We evaluated the correlation between air and urine 

cobalt levels by using the Spearman correlation coefficient.

Noise Monitoring

In February 2013, we measured area sound levels, using a Larson Davis Model 824 

integrating sound level meter. We documented the highest sound levels in approximately a 

1-minute period at each location to evaluate potential areas of concern and to identify areas 

for subsequent evaluation with noise dosimetry.

During our visit in June 2013, we took 17 full-shift time-weighted average (TWA) personal 

noise exposure measurements on employees over two shifts. We used Larson Davis 

SparkTM model 706RC integrating noise dosimeters. The noise dosimeters were attached 

to the wearer’s belt, and a small microphone was fastened to the wearer’s shirt at a point 

midway between the ear and outside of the shoulder. Windscreens provided by the dosimeter 
Health Hazard Evaluation Report 2013-0033-3238 Page 7

manufacturer were placed over the microphones to reduce or eliminate artifact noise, which 

can occur if objects bump against unprotected microphones. The dosimeters simultaneously 

collected data with three different settings to allow comparison of noise measurements at 

three different noise exposure limits: the OSHA PEL, OSHA action level (AL), and NIOSH 

recommended exposure limit (REL). The dosimeters averaged noise levels every second. 

Noise levels below the threshold level are not integrated into the dose calculation of noise 

levels. We downloaded the noise measurement information from the dosimeters with Larson 

Davis Blaze® software. We calibrated the dosimeters before and after the measurement 

periods according to the manufacturer’s instructions.

Results

Employee Interviews and Record Review

Interviews

We interviewed all 26 employees working in the building during first and second shifts. Most 

interviewed employees (n = 19) did not report symptoms that they thought were work-related 

or concerns about their work environment. However, seven (27%) reported having nasal and/

or sinus symptoms (nasal congestion, runny nose, sinus headache, post-nasal drip); five of the 

seven reported that symptoms were aggravated by work or improved away from work. Some 

employees reported blowing “black” from their noses. Three of the seven employees also 

reported respiratory symptoms (cough, shortness of breath, chest tightness, or wheezing) that 

improved away from work, and one reported skin symptoms that improved away from work. 

Medical Records Review 

We reviewed medical records of seven employees who had seen a medical provider for sinus, 

respiratory, or skin symptoms. Two of the employees’ records did not provide evidence of a 

work-related health condition. The other five employees were medically evaluated for sinus 

symptoms; three were diagnosed with sinusitis, two on the basis of abnormal computerized 

tomography findings. Three of the five with sinus symptoms were also evaluated for respiratory 

symptoms (shortness of breath, wheezing, and chest tightness). Medical diagnoses for these 

three employees included pneumonia, “asthma-like symptoms,” reactive airway disease, and 

chemical inhalation (one of the employees had more than one diagnosis). Two of these three 

employees were referred to a lung specialist and told to avoid workplace chemicals. 

OSHA Form 300 Logs of Work-related Injury and Illness Record Review

There were 14 entries in the OSHA Logs of 2010–2012 for the entire facility. The majority of 

entries (n = 10) were for musculoskeletal injuries or disorders. There was one entry in 2012 

for smoke inhalation injury. 

Workers’ Compensation Claims Record Review 

The company had 13 claims during years 2010, 2011, and 2012. The pertinent claims from 

employees of the building we evaluated included two for respiratory disorders thought to be 
Page 8 Health Hazard Evaluation Report 2013-0033-3238

due to MWF or dust exposure, one for a smoke inhalation injury from responding to a fire in 

a machine, and one for a sinus disorder thought to be due to dust exposures at work. Job titles 

of these employees included femoral finisher, machinist, and maintenance technician.

Program Review

A review of the safety program suggested that management and employee participation was 

encouraged. The internal safety consultant team and the lead safety team were responsible for 

performing safety inspections, accident investigations, and job hazard analyses. The safety 

plan also described the safety training, including new-employee orientation, specific safety 

and health programs, and job-specific safety training, as coordinated by the team leader.

The written hazard communication program had the elements required by 29 Code of Federal 

Regulations (CFR) 1910.1200, except that it did not list cobalt, chromium, or titanium as 

hazardous chemicals that were present in the workplace. The hazardous chemicals list and 

safety data sheets were maintained by the occupational safety and health coordinator. The 

program included provisions for labels to be consistent with the globally harmonized system 

of classification and labelling of chemicals and secondary container labelling. Reportedly, 

training was performed prior to assignment in a specific department and whenever chemical 

hazards or job assignments changed but this training did not include the specific hazards 

associated with cobalt, chromium, or titanium.

The written respiratory protection program had the required elements from 29 CFR 1910.134, 

including medical evaluation; fit testing; proper use, maintenance, and care of respirators; 

training; voluntary use of N95 filtering facepiece respirators; types of respirators permitted 

at the facility; and locations where specific respirators were authorized. We observed that 

all particulate filter cartridges were marked with the date they were issued and when the 

employer required that they be replaced with new cartridges. 

Sampling, Ventilation Assessment, and Observations 

Air Sampling

Results of personal air samples for total particulate, chromium, cobalt, and titanium from 

February 2013 are in Table 3. One personal air sample for cobalt taken on femoral finisher 

number 2 doing box polishing [26 micrograms per cubic meter of air (μg/m3)] exceeded the 

American Conference of Governmental Industrial Hygienists (ACGIH®) threshold limit 

value (TLV®) of 20 μg/m3. The air sample results for femoral finisher number 2 for other 

contaminants (2,100 μg/m3 for total particulate and 10 μg/m3 for chromium) were also higher 

than those for other employees, although they did not exceed applicable exposure limits. 

There are no applicable OELs for total particulates in this situation; the results, however, are 

useful for assessing overall particulate exposure. On the first day of sampling, two femoral 

finishers doing box polishing rotated in and out of the box polishing station based on the need 

for that task to be performed; therefore, at any given time throughout the day, there was either 

one, two, or three femoral finishers doing box polishing at the same time. Femoral finisher 

number 2, whose cobalt concentration exceeded the ACGIH TLV, was consistently at the box 

polishing station throughout the entire work shift. Due to the configuration of the connecting 
Health Hazard Evaluation Report 2013-0033-3238 Page 9

ducts, when more than one box polishing station was in use, the local exhaust ventilation was 

not increased but was split among the box polishing stations in use. On the following day, 

only one box polishing station was used for most of the day by one employee. 

Table 3. Personal air sample result concentrations for total particulate, chromium, cobalt, and 

titanium, February 2013

Job title Job task Sample 

duration 

(minutes)

Total 

particulate

(μg/m3)

Chromium

(μg/m3)

Cobalt

(μg/m3)

Titanium

(μg/m3)

Day 1

Metal machinist #1 Machine 

femorals

452 69 0.24 0.35 0.080

Femoral finisher #1 Femoral 

buffer

439 84 ND 0.55 0.093

Femoral finisher #2 Box polisher 228* 2100 10 26 0.53

Plastic machinist #1 Machine 

patellas

423 74 0.99 2.6 0.42

Maintenance 

tech #1

Maintenance 376 1900 1.3 3.1 9.0

Maintenance 

tech #2

Maintenance 383 810 0.5 1.4 3.2

Day 2

Titanium stem 

finisher #1

Titanium 

sandblaster

447 220 0.26 0.56 0.50

Femoral finisher #1 Box polisher 439 140 2.2 4.9 0.25

Maintenance 

tech #1

Maintenance 429 62 ND 0.25 0.13

Plastic machinist #1 Machine 

patellas

446 7 0.65 (0.17)† 0.042

NIOSH REL — Not 

applicable

500 50 Not 

applicable

OSHA PEL — Not 

applicable

1,000 100 Not 

applicable

ACGIH TLV — Not 

applicable

500 20 Not 

applicable

Minimum detectable concentration — 0.02 0.04 0.06 0.007

Minimum quantifiable concentration — 0.091 0.15 0.19 0.030

The minimum detectable concentration (MDC) and the minimum quantifiable concentration (MQC) 

were determined on the basis of an average sampling duration of 406 minutes and sample volume 

of 812 liters.

ND = Not detected

*This employee left work early on this day; 228 minutes was the employee’s full-shift exposure.

†Values in parentheses are between the minimum detectable concentration and the minimum 

quantifiable concentration, meaning there is more uncertainty associated with these results.
Page 10 Health Hazard Evaluation Report 2013-0033-3238

The maintenance technicians were exposed to dust when cleaning out the dry dust collector 

and were wearing full facepiece respirators with N95 particulate filters. The total particulate 

exposures for the maintenance technicians were 1,900 μg/m3 for one technician and 

810 μg/m3 for the other; the chromium, cobalt, and titanium concentrations in those dust 

samples did not exceed applicable exposure limits. The maintenance technicians performed 

several tasks during the initial visit. The task that generated the highest concentration of dust 

was cleaning out the baghouse dust collector from the cobalt chromium grinding and polishing 

stations. This task involved two maintenance technicians who donned full facepiece respirators 

with N95 cartridges, hoodless Tyvek® suits, and latex gloves. These employees had been 

medically cleared, trained, and fit tested to wear respirators and were included in the facility’s 

respiratory protection program. On the day of the evaluation we observed that the respirators 

were cleaned after use and stored in a sealed bag at the technicians’ workstations. They 

removed each filter cylinder from the baghouse and poured the dust into a 55-gallon receptacle, 

then replaced the filter cylinders (Figure 2). They dry-swept the spilled dust, placed it into the 

drum, and then sealed the drum. They also cleaned the wet-dust-collection system using a hose 

and shovel while wearing the same personal protective equipment.

Figure 2. Maintenance technicians cleaning out the baghouse dust collector. Photo by NIOSH.

Personal and area air sampling results for hexavalent chromium are in Appendix A, Table A1 

(personal samples) and Table A2 (area samples). One of the four personal air samples 

(0.14 μg/m3) and one of the seven area air samples (0.081 μg/m3) had quantifiable 

concentrations of hexavalent chromium. 

The personal air sampling results for MWF measured as total particulate fraction are in 

Appendix A, Table A3. MWFs were detected in only one of the three personal air samples at 

34 μg/m3, less than 10% of the NIOSH REL (500 μg/m3). Area air sampling results for MWF 

are in Appendix A, Table A4. Low concentrations of MWF were found on three of seven area 

air samples. These MWF sampling results were consistent with those previously reported by 

the consultant.
Health Hazard Evaluation Report 2013-0033-3238 Page 11

In June 2013, all personal air sample concentrations of aluminum, chromium, cobalt, 

and titanium were well below their respective OELs (see Table 4). Detailed results for 

personal air samples are in Appendix A, Table A5. The highest cobalt concentrations 

(7.6 and 5.0 μg cobalt/m3) were measured on the femoral finishers working the first and 

second polishing and buffing stations (Table A5). In addition, these femoral finishers had the 

highest exposure to aluminum (4.5 and 3.6 μg aluminum/m3), which is not surprising because 

they used an aluminum buffing compound. The chromium concentration was also highest on 

the two femoral finishing employees who worked at these polishing stations (2.7 and 2.2 μg 

chromium/m3). The titanium concentrations collected on titanium stem polishers were low, 

ranging from “not detected” to 1.9 μg/m3.

Table 4. Summary of personal air sample concentration results, June 2013

Substance* Sample 

results

OSHA PEL

(μg/m3)

NIOSH REL

(μg/m3)

ACGIH TLV

(μg/m3)

Aluminum ≤ 4.5 15,000 10,000 1,000†

Chromium ≤ 2.7 1,000 500 500

Cobalt ≤ 7.6 100 50 20

Titanium ≤ 1.9 Not applicable Not applicable Not applicable

*16 samples were collected for each substance.

†This limit is for the respirable fraction of the dust, but we collected total dust samples, which 

includes the respirable fraction and larger, inhalable dust particles.

Surface Sampling

We detected chromium, cobalt, and titanium in most of the surface samples we collected 

on February 2013, including those from nonproduction areas (Appendix A, Table A6). As 

expected, samples collected in the production area had the highest levels of metals. The 

concentrations were lower in non-production areas. The floor in front of the men’s restroom 

(9.4 micrograms per 100 squared centimeters [μg/100 cm2] chromium, 22 μg/100 cm2

cobalt), the break room floor (3.1 μg/100 cm2 chromium, 7.0 μg/100 cm2 cobalt), the break 

room door handle (2.9 μg/100 cm2 chromium, 5.1 μg/100 cm2 cobalt), and the refrigerator 

handle in the break room (2.3 μg/100 cm2 chromium, and 1.0 μg/100 cm2 cobalt) had 

detectable levels of chromium (1.0 μg/100 cm2). We measured 3.1 μg/100 cm2 titanium on 

the break room door handle, however all other titanium results were between the limit of 

detection (0.007 μg/100 cm2) and 0.35 μg/100 cm2. 

We performed additional wipe sampling in June 2013. Complete wipe sample testing results 

are in Appendix A, Table A7. We found chromium, cobalt, and titanium in nonproduction 

areas, including areas where employees ate and drank. These metals were also found inside 

employees’ gloves. We found the highest aluminum level (12 μg/100 cm2) on the door handle 

to the break area. The highest chromium (5.0 μg/100 cm2 and 4.8 μg/100 cm2) and cobalt 

(11 μg/100 cm2 and 11 μg/100 cm2) levels were found on the break room counter by the 

coffee maker and the top stair to the break area, respectively. 
Page 12 Health Hazard Evaluation Report 2013-0033-3238

Bulk MWF Sampling

The three bulk samples of used MWF showed higher concentrations of chromium and cobalt 

than shown in the three unused MWFs.

Ventilation

The cobalt chromium femoral grinding and polishing operations had hard metal ventilation 

ducts terminating at a baghouse dust collector located outside, on the other side of the exterior 

wall from each process. Each polishing station was attached to the metal duct with plastic 

flexiduct (Figure 3). The box polishing station, located at the far end of the cobalt chromium 

polish area, was attached to the exhaust ventilation system with flexible duct that had to be 

manually opened by lifting a damper when the box polishing stations were used. The titanium 

stem grinding operation was attached to a wet dust collector, located next to the dry dusthandling system outdoors. The nitric passivation room had a recirculating air handler that 

passed air through a charcoal filter before releasing it back into the room (Figure 4).

Figure 3. Local exhaust ventilation at one of the buffing/polishing stations. Photo by NIOSH.

Figure 4. Local exhaust ventilation at the nitric acid passivation tank. Photo by NIOSH.
Health Hazard Evaluation Report 2013-0033-3238 Page 13

Employees working at the box polishing station could be unnecessarily exposed to dust 

because the setup of the exhaust ventilation was not optimal. In February 2013, we found that 

the exhaust ventilation at the box polishing station was unable to capture smoke at the face of 

the femoral finisher doing box polishing. The ducts connected to this station had a 90° turn 

and multiple twists in the flexible duct (Figure 5), features that reduce the capture velocity 

and thus the effectiveness of the local exhaust ventilation system.

Figure 5. Local exhaust ventilation at the box polishing station. Photo by NIOSH.

The “metals only” burr grinders (adjacent to the patellar lathes) captured smoke poorly, 

indicating insufficient airflow. During our evaluation the maintenance technicians replaced 

the dust collector’s filter bag in an attempt to improve performance. Afterward, the dust 

collector’s ability to capture smoke improved. In the passivation room, the slot hood for the 

nitric acid wash had a flexible duct that was long and twisted, which could lead to inefficient 

vapor capture (Figure 6).

Figure 6. Excess duct in the nitric passivation area. Photo by NIOSH.
Page 14 Health Hazard Evaluation Report 2013-0033-3238

Workplace Observations

We did not observe mold or signs of water damage in the newly renovated break room. In 

addition, we discussed with the maintenance staff all the repairs and renovations performed 

in the break room, which seemed sufficient to address the previously existing mold problem.

The patella-shaping lathe was designed to function as an enclosed machining cabinet; 

however, the door closer had been overridden so that the operator could manually hold the 

polymer puck to a spinning support as the lathe shaped it. The employees did this to catch 

the polymer shavings before they could build up and dislodge the patella (Figure 7). We 

recommended that a device be developed to hold the puck in place so that the operator would 

not need to hold it manually. This was done prior to our second visit, and an interlock was 

installed on the machine to prevent the operator from opening the door to the patella lathe 

while it was running.

Figure 7. Plastic patella lathe. Photo by NIOSH.

We had the following additional observations:

● One of the cabinets used to sandblast a rough finish on all exposed surfaces of the implants 

had worn out seals that allowed clouds of dust to be released from the sandblaster. 

● Femoral finishing employees were observed using compressed air to blow dust off 

themselves and the femoral implants. 

● Natural rubber latex gloves were used throughout the facility. 

● Some employees in the finishing department voluntarily wore an N95 filtering facepiece 

respirator when polishing parts, but the respirators were not always worn correctly. For 

example, the metal nose clip was not properly molded to the user’s nose, facial hair 

interfered with a proper face seal, or the bottom neck strap was not worn consistently. 

● Some disposable respirators were used beyond the time limit recommended by 

the manufacturer.

● Employees handled parts covered in MWF with their bare hands. 
Health Hazard Evaluation Report 2013-0033-3238 Page 15

Questionnaire

In June 2013, all 26 employees working in the building completed a questionnaire; 21 had 

participated in the first site visit interviews. Their average age was 43 (range, 25 to 62 years), 

and the average number of years worked at the company was 5 (range, 2 months to 20 years). 

Two of the employees were female. When asked about smoking history, 12 employees reported 

never smoking, 8 reported being former smokers, and 6 reported they were current smokers.

When asked at what job they spent the most time during the previous 12 months, employees 

reported the following: metal implant machining (n = 6); finishing (n = 13, including femoral 

finishing [11], and titanium stem finishing [2]); maintenance (n = 3); passivation (n = 2); 

laser operating (n = 1); and plastic implant machining (n = 1). Thirteen employees reported 

handling used MWF or parts wet with MWF in the past 12 months; eight usually wore gloves 

when handling used MWF or parts wet with MWF. Seventeen reported polishing or buffing 

parts in this time period; thirteen usually wore gloves and two sometimes wore gloves when 

polishing or buffing parts. 

Four employees reported having two or more episodes of illness in the 12 months prior to 

the evaluation, with two or more of the following symptoms: cough, wheeze, shortness of 

breath, or chest tightness. None had fever or weight loss with these symptoms. Table 5 shows 

the number of employees who reported specific symptoms within the 12 months prior to our 

evaluation and the number who reported that the symptom improved away from work. 

Table 5. Reported symptoms among 26 employees in the 12 months prior to the evaluation 

Symptom Number of employees 

reporting symptom

Number reporting symptoms 

improving away from work

Nasal congestion, runny nose, 

sneezing (not from cold or flu)

12 5

Nasal symptoms with itchy, 

watery eyes

6 Not applicable*

Wheezing in chest 5 3

Pneumonia or chest flu 4 Not applicable*

Chest tightness upon waking 3 3

Attack of asthma 2 2

*We did not ask about days away from work for these symptoms.
Page 16 Health Hazard Evaluation Report 2013-0033-3238

Questionnaire Analysis

We compared the prevalence of symptoms (wheeze, chest tightness, asthma, nasal symptoms, 

and dermatitis on fingers, hands, wrists, forearms, face, or neck) that improved away 

from work for employees with MWF exposure in the 12 months prior to the evaluation 

(n = 13) and employees without such exposure (n = 13). MWF exposure was not statistically 

significantly associated with employee reports of skin or respiratory symptoms. 

We compared the prevalence of symptoms (wheeze, chest tightness, asthma, nasal symptoms, 

and dermatitis on fingers, hands, wrists, forearms, face, or neck) that improved away 

from work for employees with (n = 17) and without (n = 9) buffing/polishing exposure in 

the 12 months prior to the evaluation. Buffing or polishing exposure was not statistically 

significantly associated with employee reports of skin or respiratory symptoms.

When we looked at the 11 employees who reported spending the most time finishing 

femoral implants in the 12 months prior to our evaluation, we found a statistically significant 

association (P < 0.01) between working as a femoral finisher and having nasal symptoms that 

improved away from work. We also found a statistically significant association (P = 0.04) 

between working in this job and having dermatitis that improved away from work on the 

hands, fingers, wrists, forearms, face, or neck (Table 6). All five of the employees reporting 

dermatitis in the prior 12 months were femoral finishers. Three of the five reported that 

their dermatitis was better when away from work more than 5 days; two reported that they 

had not been away from work more than 5 days and therefore could not say whether it was 

better away from work. Two of the five had dermatitis at the time of the questionnaire. Two 

employees had seen a doctor for their dermatitis in the 12 months prior to the evaluation. We 

reviewed medical records for one of these employees and they did not reveal a diagnosis for 

a skin condition.

Table 6. Number of employees reporting symptoms that improved on days away from work among 

femoral finishers versus other job groups in the 12 months prior to the evaluation

Symptom Femoral finishers 

(n = 9 to 11)

Other job groups 

(n = 15)

P value

Nasal congestion, runny nose, sneezing 

(not from cold or flu)

5 0 < 0.01

Nasal symptoms with itchy, watery eyes 3 0 0.052

Dermatitis (hands, fingers, wrists, 

forearms, face, or neck)

3 0 0.04

Wheezing in chest 3 0 0.06

Chest tightness upon waking 3 0 0.06

Attack of asthma 2 0 0.17
Health Hazard Evaluation Report 2013-0033-3238 Page 17

Biological Exposure Monitoring

Of the 26 employees, 24 participated in the biological sampling and reported spending the most 

time during the week of the evaluation at the following jobs: finishing (n = 12), metal implant 

machining (n = 5), maintenance (n = 3), passivation (n = 2), laser operating (n = 1), and plastic 

implant machining (n = 1). Fourteen employees reported polishing or buffing parts during the 

week of our evaluation; 11 of the 14 reported usually wearing gloves during that workweek 

when polishing or buffing parts. No employees reported participating in hobbies that involved 

artist paints, glazes, or stains during the week of the evaluation. No employees reported ever 

having joint replacement surgery with a metal replacement joint. Nine employees reported 

taking vitamins during the week of our evaluation. We did not see a meaningful difference in 

urine cobalt levels between employees who did and did not take vitamins.

Three employees had creatinine levels outside the range that ACGIH has suggested is valid 

(0.5 to 3 grams per liter), so we could only accurately interpret the remaining 21 employees’

urine cobalt and chromium levels.

Cobalt

All 21 employees had urine cobalt levels below the ACGIH biological exposure index (BEI®). 

The median urine concentration of cobalt among the 21 employees was 0.6 micrograms per 

liter (μg/L) (range, 0.3–2.0 μg/L), which is well below the BEI for cobalt (15 μg/L). 

Chromium

All 21 employees had urine concentrations of chromium less than 1.0 μg/L (the limit of 

detection), which is well below the BEI for chromium (25 μg/L). 

Comparing Questionnaire, Sampling, and 

Biomonitoring Data

Comparing Questionnaire Data with Air and Urine Cobalt Data 

We found that those spending the most time in femoral finishing during the week of 

our second visit had significantly higher personal air cobalt levels (median = 1.2 μg/m3; 

range, 0.13–7.6 μg/m3; n = 8) than those working at other jobs (median = 0.11 μg/m3; range, 

0.045–2.8 μg/m3; n = 9) (P = 0.03). We also compared urine cobalt levels for these two job 

groups. Femoral finishers had higher median urine cobalt levels (median = 0.95 μg/L; range, 

0.30–2.0 μg/L; n = 8) than those working most of the time in other jobs (median = 0.50 μg/L; 

range, 0.50–1.0 μg/L; n = 13), but the difference was not statistically significant (P = 0.10).

Comparing Urine Cobalt Data with Air Cobalt Data

The correlation coefficient for the air and urine cobalt measurements was positive (r = 0.41), 

but it was not statistically significant (P = 0.18). 
Page 18 Health Hazard Evaluation Report 2013-0033-3238

Noise Monitoring

Personal noise dosimetry measurements are in Appendix A, Table A8. We measured full-shift 

noise exposures for all job categories in the building, except the maintenance technicians. 

OSHA and NIOSH use different criteria for measuring TWA noise exposures (see Appendix 

B). Although the NIOSH REL for noise is not a legally enforceable noise-exposure limit, it is 

more protective than the OSHA PEL in preventing hearing loss [NIOSH 1998b]. On the basis 

of the NIOSH, OSHA AL, and OSHA PEL criteria, the full-shift results measured according 

to each respective convention were 74 to 96 decibels, A-scale (dBA), 67 to 93 dBA, and 67 to 

93 dBA. Twelve of the 17 noise exposures exceeded the NIOSH REL, 6 exceeded the OSHA 

AL, and 1 exceeded the OSHA PEL. The job titles that were over the NIOSH REL included 

the femoral finishers working at the buffing and polishing stations, titanium finishers, the nitric 

passivation operators, and the femoral finishers working on the tumbler polishing stations. A 

cobalt polishing/buffing operator had the highest noise exposure (93 dBA on the basis of OSHA 

criteria, or 96 dBA on the basis of NIOSH criteria, averaged over an 8-hour work shift). The 

lowest noise levels were measured on the drag finishers and the machinists.

Insert-type hearing protectors (earplugs) were available for use, but we observed very few 

employees using them. Some of the employees using these hearing protectors did not insert 

them deeply enough in the ear canal, a deficiency which can reduce the noise attenuation. 

None of the employees were enrolled in a hearing conservation program, nor did they have 

periodic training and annual audiometric tests. 

Discussion

Our evaluation found employee exposures to MWF, cobalt, chromium, and hexavalent 

chromium. Each of these substances can result in nasal symptoms and contact dermatitis, 

both irritant and allergic [Gheysens et al. 1985; Burton et al. 2012; Walters et al. 2012]. 

The results of our exposure assessment, medical interviews, and analysis of the health 

questionnaire suggest that cobalt dust exposure was a likely cause of nasal, respiratory, and 

skin symptoms reported by femoral finishers. We found one high airborne cobalt dust level 

at the box polishing station during our first visit and a statistically significant relationship 

between working as a femoral finisher (finishing cobalt-chromium parts) and having workrelated nasal and skin symptoms. One limitation of our data is that our sampling results do 

not reflect the variability in exposures that occur over time, and therefore, exposures on 

different days could be higher or lower. On our second site visit, we found low air and urine 

cobalt levels among employees indicating low overall exposure to cobalt. Despite the low 

cobalt levels, caution is still needed because very small levels of cobalt exposure in sensitized 

individuals could lead to skin allergy or an asthma-like allergy.

We found that the air and urine cobalt results were only weakly correlated. Although 

employees with higher air cobalt results did tend to have higher values of urine cobalt, 

knowing the air sampling results alone do not give enough information to predict their urine 

cobalt levels accurately. The small number of air and urine samples collected and the short 

sampling time period could have limited our statistical findings. In addition, skin exposure 

from contaminated surfaces, and ingestion of cobalt through contaminated skin, food, and 
Health Hazard Evaluation Report 2013-0033-3238 Page 19

drink, possibly contributed to cobalt exposure among all production employees. 

Employees can be exposed to hexavalent chromium as a by-product of heat-producing tasks 

such as welding, sanding, or grinding on products containing chromium. The personal and 

area air sampling results, although below OELs, indicate that finishing cobalt-chromium 

femorals resulted in airborne hexavalent chromium. The personal air sample results for 

hexavalent chromium for the femoral finisher doing box polishing was 0.14 μg/m3, more than 

half the NIOSH REL of 0.2 μg/m3 [NIOSH 2013]. Hexavalent chromium is carcinogenic 

to humans and is associated with cancer of the lung, nose, and nasal sinuses [IARC 2012; 

NIOSH 2013]. A 2015 study suggests that hexavalent chromium is associated with an 

increased risk for stomach cancer [Welling et al. 2015]. Occupational hexavalent chromium 

exposure has also been associated with irritation or damage to the nose, throat, lungs, eyes, 

and skin, including allergic contact dermatitis.

We found low air concentrations of MWF but no association between employee respiratory 

or skin symptoms and working as a machinist, indicating that MWF exposures do not appear 

to be resulting in health problems at this facility. However, machinists could have cobalt 

and chromium exposure from the tungsten carbide machining tools. Studies have found that 

machining with these tools can potentially leach cobalt and chromium into MWFs [Sjogren et 

al. 1980; Walters et al. 2012], which can be inhaled via MWF mist or contacted through skin 

contamination. Our results for cobalt and chromium in used MWF samples were consistent 

with this finding. Many types of MWFs contain potential skin allergens and irritants. In 

addition, heavy metals such as cobalt can be absorbed into the fluids and transferred to the 

employee’s skin. Persons who are sensitized to chromium or cobalt may experience an 

allergic reaction if these metals touch the skin or are inhaled.

We found aluminum in the air at very low concentrations. Because the air concentrations 

of aluminum were very low, it is unlikely that employees would develop health problems 

associated with airborne aluminum exposure (Appendix B). 

Aluminum, chromium, cobalt, and titanium were found on non-production area surfaces. 

This finding indicates that metals were migrating out of the production area and onto surfaces 

throughout the facility, including the break room, refrigerator, and conference room where we 

held interviews. Although there are no OELs for the substances we sampled on surfaces, the 

presence of these metals outside the production area could contribute to employee exposure 

through ingestion. The presence of these metals on surfaces contributes to overall exposure 

and can lead to sensitization. In persons sensitized to these metals, skin contact with the 

offending metal can result in allergic contact dermatitis.

Some employees wore latex gloves. Latex can cause irritant contact dermatitis, allergic 

contact dermatitis, and immediate hypersensitivity [NIOSH 1997]. Because of the severity 

of symptoms that sensitized individuals my experience, latex should be avoided in most 

occupational settings.

We found noise exposures above the NIOSH REL among cobalt polishers/grinders, titanium 

stem grinders, nitric passivation operators, and tumbler/polishers; some noise exposures were 

above the OSHA PEL and AL. The company did not have a hearing conservation program 
Page 20 Health Hazard Evaluation Report 2013-0033-3238

and few employees wore hearing protection. Engineering controls are the most effective in 

preventing noise induced hearing loss among employees and reduce the need for employees 

to wear hearing protection. Because effective noise engineering controls can be challenging 

to design and implement, noise reduction should be considered as part of an overall longterm strategy. For example, when equipment is replaced, the amount of noise generated by 

the new equipment should be considered in the purchasing decision. 

Conclusions

We determined that a health hazard from airborne cobalt exposure existed in the femoral 

finishing department box polishing station. However, improvements made to the finishing 

department’s local exhaust ventilation system helped lower airborne cobalt levels. We also 

determined that femoral finishers working at the box polish station had exposure to airborne 

hexavalent chromium, an human carcinogen, up to half of the NIOSH REL. Cobalt, chromium, 

and aluminum surface contamination in the employee break room posed a risk to employees 

from skin contact and ingestion, both possibly leading to sensitization. Exposure to MWFs and 

metal contaminants present in the fluids can also result in skin and respiratory sensitization 

though we did not find evidence of this in our evaluation. We found that employees were 

overexposed to noise in the polishing and buffing areas and in the nitric passivation room, but 

no hearing conservation program was in place. We did not find evidence of mold growth or 

water damage in areas where mold growth had been found previously. 

Recommendations

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

medical implant manufacturer to use a labor-management health and safety committee or 

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

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

specific situation at the facility. 

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

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

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

install engineering controls to reduce exposure or shield employees. Until such controls 

are in place, or if they are not effective or feasible, administrative measures and personal 

protective equipment may be needed. 

Engineering Controls

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

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

effectively without placing primary responsibility of implementation on the employee. 

1. Install engineering controls at noisy equipment in the nitric passivation room and 

buffing/polishing area to reduce noise exposures. Consult with an acoustic engineer for 

specific guidance on noise control strategies.
Health Hazard Evaluation Report 2013-0033-3238 Page 21

2. Optimize the local exhaust ventilation system over the nitric acid passivation tank by 

installing a short, hard duct; removing unnecessary ductwork; and eliminating 90° 

turns. Re-evaluate the ventilation system performance after changes are made.

3. Perform periodic preventive maintenance on all local exhaust ventilation units.

4. Replace the worn-out gaskets on the older sandblasting hoods. 

5. Design a holding tool for the dip seal process so that employees do not have to use 

their fingers to dip the parts in hot liquid.

Administrative Controls

Administrative controls are 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 the 

policies and procedures are followed consistently.

1. Implement a hearing conservation program for all employees who work in the buffing, 

polishing, and grinding area and those who work in the nitric passivation room. The 

program should include annual audiometric testing and training. More information 

on establishing a hearing conservation program can be found at http://www.cdc.gov/

niosh/docs/98-126/pdfs/98-126.pdf, http://www.osha.gov/dts/osta/otm/noise/hcp/

index.html, and http://www.osha.gov/Publications/osha3074.pdf.

2. Improve hazard communication training to include the hazards and potential health 

effects associated with cobalt, chromium, solvents, and other chemical exposures in 

the workplace. Emphasize proper work practices, hand hygiene, and skin protection 

techniques that prevent exposure to these substances. 

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

hazards and potential health effects associated with MWF exposure. Guidelines for 

MWF training are included in the 1998 NIOSH document What You Need to Know 

About Occupational Exposure to Metalworking Fluids, available at: http://www.cdc.

gov/niosh/pdfs/98-116.pdf. 

4. Stop employees from using compressed air to clean work clothing. If needed, vacuum 

dust from work clothing and parts using a high-efficiency particulate arrestance air 

filter vacuum with nozzle. 

5. Collect additional personal air samples for hexavalent chromium to further 

characterize worker exposures and to determine if exposure controls and medical 

monitoring programs should be implemented.

6. Conduct periodic air sampling for cobalt around the box polishing station to ensure 

that concentrations remain below OELs. 

7. Improve housekeeping procedures in nonproduction areas and encourage personal 

hygiene such as hand washing after glove removal and prior to eating and drinking to 

reduce the risk of ingesting metals.
Page 22 Health Hazard Evaluation Report 2013-0033-3238

8. Encourage employees to report potential work-related health conditions to their 

supervisor. Employees with persistent symptoms should be evaluated by an 

occupational medicine physician or a medical provider specializing in workplace 

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

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

9. Look for health problem or injury trends reported in company injury and illness logs 

that may be related to particular job duties, work materials, machines, or areas of the 

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

develop an intervention to reduce exposures.

Personal Protective Equipment

Personal protective equipment is the least effective means for controlling hazardous 

exposures. Proper use of personal protective equipment requires a comprehensive program 

and a high level of employee involvement and commitment. The right personal protective 

equipment must be chosen for each hazard. Supporting programs such as training, changeout schedules, and medical assessment may be needed. Personal protective equipment should 

not be the sole method for controlling hazardous exposures; it should be used until effective 

engineering and administrative controls are in place.

1. Provide nitrile gloves instead of natural rubber latex gloves to protect employees’ skin 

from dermal exposures, including MWFs, parts covered with MWF, and metal dusts. 

Train employees on proper glove wear and on visual signs that the glove material is 

worn out, so that they recognize when they need new gloves. Additional information 

on the occupational hazards associated with latex exposure can be found in the NIOSH 

Alert Preventing Allergic Reactions to Natural Rubber Latex in the Workplace, 

available at http://www.cdc.gov/niosh/docs/97-135/.

2. Require employees to wear hearing protection when buffing and polishing parts 

and when they are in the nitric passivation room until engineering controls are 

demonstrated to reduce noise exposures below the NIOSH REL.

3. Encourage employees who voluntarily use disposable filtering facepiece respirators to 

wear them properly. Guidelines for putting on and taking off a disposable respirator 

are available at http://www.cdc.gov/niosh/docs/2010-133/pdfs/2010-133.pdf. 
Health Hazard Evaluation Report 2013-0033-3238 Page 23

Appendix A: Tables

Table A1. Hexavalent chromium concentrations in personal air samples, February 2013

Job title Job task Minutes sampled Concentration (μg/m3)

Femoral finisher Box polishing 431 0.14

Femoral finisher Finisher III, first polish 446 (0.010)*

Femoral finisher Polish/buff 431 ND

Femoral finisher Trim and blast (hand tool) 451 (0.030)

NIOSH REL — 0.2

OSHA PEL — 5

ACGIH TLV — 10

The MDC was 0.01 μg/m3 and the MQC was 0.050 μg/m3 on the basis of an average sample 

duration of 456 minutes and sample volume of 912 liters. 

*Values in parentheses are between the MDC and the MQC, meaning there is more uncertainty 

associated with these results.

Table A2. Hexavalent chromium concentration in area air samples, February 2013

Area Minutes sampled Concentration (μg/m3)

Cobalt chrome, hand tool, trim and blast 425 ND

Cobalt chrome, work in progress cans 426 ND

Titanium, stem cell grind 427 ND

Between box polishing stations 525 (0.02)*

Trim and blast half, box polishing 436 0.081

Cobalt/chrome by sandblaster 508 ND

By belt sander in cobalt/chrome 512 ND

The MDC was 0.01 μg/m3 and the MQC was 0.05 μg/m3 on the basis of an average sample 

duration of 456 minutes and sample volume of 912 liters. 

*Values in parentheses are between the MDC and the MQC, meaning there is more uncertainty 

associated with these results.
Page 24 Health Hazard Evaluation Report 2013-0033-3238

Table A3. MWFs in air, measured as total particulate fraction in personal samples, February 2013

Job title Minutes sampled Concentration (μg/m3)

Machinist, grinder operator 443 (34)*

CNC lathe grinder operator 445 ND

Maintenance technician 450 ND

NIOSH REL — 500

The MDC was 24 μg/m3 and the MQC was 120 μg/m3 on the basis of an average sample duration 

of 420 minutes and sample volume of 840 liters. 

*Values in parentheses are between the MDC and the MQC, meaning there is more uncertainty 

associated with these results.

Table A4. MWFs in air, measured as total particulate fraction in area samples, February 2013

Area Minutes sampled Concentration (μg/m3)

Grinder number 1 259 (38)*

Haas grinder 430 (23)

Behind the grinders, by door 425 ND

Grinder 1, by operator access point 437 (34)

Backside of grinder 3 439 ND

Grinder 3, by operator 438 (23)

Haas grinder 437 ND

The MDC was 24 μg/m3 and the MQC was 120 μg/m3 on the basis of an average sample duration 

of 409 minutes and sample volume of 840 liters.

*Values in parentheses are between the MDC and the MQC, meaning there is more uncertainty 

associated with these results.
Health Hazard Evaluation Report 2013-0033-3238 Page 25

Table A5. Metal concentrations in personal air samples, June 2013

Job Title Job Task Minutes 

sampled

Aluminum

(μg/m3)

Chromium

(μg/m3)

Cobalt

(μg/m3)

Titanium

(μg/m3)

Day 1: First shift

Femoral finisher #1 Drag finish 443 2.6 ND 0.17 (0.020)*

Titanium stem 

finisher

Titanium polish 354 ND (0.99) 2.8 1.2

Femoral finisher #2 Box polishing 463 ND (0.60) 1.3 0.35

Femoral finisher #3 Mask and blast 439 (1.3) (0.65) 1.1 0.081

Metal machinist #1 Machining/

grinding

458 ND ND (0.045) ND

Femoral finisher #4 Tumbler/polish 456 ND ND 0.11 0.19

Day 1: Second shift

Femoral finisher #1 1st cobalt polish 466 4.5 2.7 7.6 0.055

Femoral finisher #2 2nd cobalt polish 470 3.6 2.2 5.0 0.10

Metal machinist #1 Machining/

grinding

455 ND ND (0.081) ND

Femoral finisher #3 Buffing/polishing 464 (1.1) (0.67) 1.3 (0.023)

Titanium stem 

finisher

Titanium 

polishing

445 ND ND 0.19 1.9

Plastic machinist Implant 

machinist

424 ND ND 0.11 (0.012)

Day 2: First shift

Metal machinist #1 Machining/

grinding

436 ND ND (0.67) ND

Titanium stem 

finisher

Titanium polish 446 ND ND (0.07) 0.49

Femoral finisher #1 Drag finish 430 ND ND 0.13 0.020

Femoral finisher #4 Tumble/polish 438 ND ND (0.060) 0.050

Femoral finisher #3 Mask and blast 378 (1.5) ND 0.72 0.36

OSHA PEL — 15,000 1,000 100 Not 

applicable

NIOSH REL — 10,000 500 50 Not 

applicable

ACGIH TLV — 1,000† 500 20 Not 

applicable

Minimum detectable concentration — 0.7 0.4 0.04 0.01

Minimum quantifiable concentration — 2 1 0.1 0.03

The MDC and MQC were determined on the basis of an average sample duration of 432 minutes and sample 

volume of 864 liters.

*Values in parentheses are between the MDC and the MQC, meaning there is more uncertainty associated 

with these results.

†Respirable fraction of the sample; we measured the total particulate fraction which includes respirable and 

other inhalable particles.
Page 26 Health Hazard Evaluation Report 2013-0033-3238

Table A6. Metals found in surface wipe samples, February 2013

Areas Chromium

(μg/100 cm2)

Cobalt

(μg/100 cm2)

Titanium

(μg/100 cm2)

Non-production areas

Interview room table 0.3 0.61 0.074

Conference room table 0.078 ND 0.019

Carpet in main hall 0.14 0.23 0.022

Doorknob from production* 0.99 2.3 0.12

Floor in front of men’s restroom 9.4 22 0.26

Maintenance tech’s workstation 0.49 0.92 0.098

Maintenance tech’s workstation 0.72 1.6 0.043

Break room microwave 0.23 0.27 ND

Break room floor 3.1 7 0.22

Break room refrigerator handle* 2.3 1 0.35

Break room table 0.12 0.22 0.087

Break room door handle* 2.9 5.1 3.1

Production Areas

Box Polishing station 76 180 1.1

Cobalt/chromium polish station 320 760 7.5

Titanium polish workstation 95 210 170

Limit of detection 0.4 0.06 0.007

*These were irregular surfaces, and 100 cm2 was estimated

Table A7. Metals found in surface wipe samples, June 2013

Areas Aluminum

(μg/100 cm2)

Chromium

(μg/100 cm2)

Cobalt

(μg/100 cm2)

Titanium

(μg/100 cm2)

Non-production areas

Break room table, after lunch 1.2 0.1 0.13 0.04

Door into break room, on wood 5.3 2.5 6.3 0.21

Break room counter, by coffee 

maker

2 5 11 0.23

Door handle to break area* 12 0.87 1.9 0.22

Water fountain* 1.7 0.21 0.43 ND

Exit button from production area* ND 4.3 2.5 0.029

Top stair to the break area 2.2 4.8 11 0.08

Production areas

Floor in front of patella area 2 2.3 5.3 0.1

Inside gloves at mask and blast* 1.7 2.6 6.1 0.053

Inside gloves at titanium stem grind* ND 1.2 2.7 0.27

Haas “C” machinist mouse* 2.6 3.2 7.1 0.14

Limit of detection 1.0 0.03 0.06 0.02

*These were irregular surfaces, and 100 cm2 was estimated
Health Hazard Evaluation Report 2013-0033-3238 Page 27

Table A8. Noise dosimeter results by job task, June 2013

Job titles Job tasks OSHA AL

(dBA)

OSHA PEL

(dBA)

NIOSH REL

(dBA)

Sample duration 

(hours:minutes)

Femoral finisher #1 Drag finishing 70 69 78 7 h: 24 min

Femoral finisher #2 Drag finishing 75 74 80 7 h: 10 min

Femoral finisher #3 Box polishing 89 88 90 7 h: 43 min

Femoral finisher #4 Mask and 

blasting

82 82 87 7 h: 20 min

Femoral finisher #5 Mask and 

blasting

83 82 88 6 h: 16 min

Femoral finisher #6 Tumbler 

polishing

87 86 91 7 h: 37 min

Femoral finisher #7 Tumbler 

polishing

84 83 89 7 h: 18 min

Femoral finisher #8 Hand cobalt 

polishing

85 85 87 7 h: 24 min

Femoral finisher #9 Cobalt 

polishing

81 79 87 5 h: 48 min

Femoral finisher #10 Cobalt 

polishing

93 93 96 7 h: 52 min

Metal machinist #1 Femoral 

machining

75 75 80 7 h: 39 min

Metal machinist #2 Femoral 

machining

67 67 74 7 h: 29 min

Titanium finisher #1 Titanium 

stem 

polishing

87 87 89 7 h: 51 min

Titanium finisher #2 Titanium 

stem 

polishing

81 80 84 7 h: 25 min

Nitric passivation 

operator #1

Nitric 

passivation

84 84 91 7 h: 35 min

Nitric passivation 

operator #2

Nitric 

passivation

80 79 86 7 h: 42 min

Nitric passivation 

operator #3

Nitric 

passivation

85 85 93 7 h: 05 min

Exposure limits 85 90 85

Note: Areas in grey indicate an overexposure
Page 28 Health Hazard Evaluation Report 2013-0033-3238

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 TWA exposure. A TWA refers to the average exposure during 

a normal 8- to 10-hour workday. Some chemical substances and physical agents have 

recommended short term exposure limits (STELs) or ceiling values. Unless otherwise noted, 

the STEL is a 15-minute TWA exposure. It should not be exceeded at any time during a 

workday. The ceiling limit should not be exceeded at any time.

In the United States, OELs have been established by federal agencies, professional 

organizations, state and local governments, and other entities. Some OELs are legally 

enforceable limits; others are recommendations.

● The U.S. Department of Labor OSHA PELs (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 (such as 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.

● Other OELs commonly used and cited in the United States include the TLVs, which 

are recommended by ACGIH, a professional organization, and the workplace 

environmental exposure levels (WEELs), which are recommended by the American 

Industrial Hygiene Association, another professional organization. The TLVs and 

WEELs are developed by committee members of these associations from a review of 

the published, peer-reviewed literature. These OELs are not consensus standards. TLVs 

are considered voluntary exposure guidelines for use by industrial hygienists and others 
Health Hazard Evaluation Report 2013-0033-3238 Page 29

trained in this discipline “to assist in the control of health hazards” [ACGIH 2015]. 

WEELs have been established for some chemicals “when no other legal or authoritative 

limits exist” [AIHA 2015].

The ACGIH BEI is a concentration below which nearly all workers will not experience 

adverse health effects. They are correlated with TLVs, i.e., air levels of chemicals. BEIs are 

set by ACGIH and are voluntary guidelines for making decisions regarding safe levels of 

exposure to various chemical substances and physical agents found in the workplace. 

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/Gefahrstoffdatenbanken/GESTIS-InternationaleGrenzwerte-für-chemische-Substanzen-limit-values-for-chemical-agents/index-2.jsp, 

contains international limits for more than 1,500 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 (such as local exhaust ventilation, process enclosure, and dilution ventilation), 

(3) administrative controls (such as employee training, work practice changes, medical 

surveillance, and limiting time of exposure), and (4) personal protective equipment (such 

as respiratory protection, gloves, eye protection, and 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 it can be used to supplement existing OELs.

Below we provide the OELs for cobalt, chromium, hexavalent chromium, MWF, and 

aluminum (Table B1), as well as a discussion of their potential health effects. There are no 

OELs and limited information on health effects from exposure to titanium metal. OELs for 

titanium dioxide exist, but this compound has properties and effects that differ from titanium 

metal and is beyond the scope of this evaluation.
Page 30 Health Hazard Evaluation Report 2013-0033-3238

Table B1. Occupational exposure limits for metals

Substance OSHA PEL

(μg/m3

)

NIOSH REL

(μg/m3)

ACGIH TLV

(μg/m3)

Cobalt 100 50 20

Total chromium 500 500 500

Hexavalent chromium 5.0 0.2 10*

MWF 500 500† —

Aluminum 15,000 10,000 1,000 (R)

(R) = respirable fraction only. We measured the total aerosol fraction.

*As insoluble hexavalent chromium compounds

†For up to 10 hours per day during a 40-hour workweek as the total particulate fraction

Cobalt

Cobalt is an essential element and is present in the human diet in tiny amounts. Dietary cobalt 

exposure is unlikely to affect occupational urine biomonitoring measurements. Occupational 

cobalt exposure comes from metallurgical industries where metals containing cobalt are 

processed by grinding, drilling, and sanding. Cobalt is used as a pigment in some artist 

supplies. Patients who have undergone total hip replacement have been shown to have urine 

cobalt levels exceeding the upper normal value of the BEI [ACGIH 2001]. Vitamins may 

contain vitamin B12, or cyanocobalamin, which contains cobalt. Persons taking multivitamin 

pills containing cobalt have been shown to have increased cobalt excretion in the urine 

[ACGIH 2001]. In the general population of Western countries, the average concentration of 

cobalt in adult urine ranges between 0.1 and 2 μg/L [ACGIH 2001]. The BEI for end-of-shift, 

end-of-workweek cobalt in urine is 15 μg/L. OSHA does not have a legal requirement for 

levels of urine cobalt.

Cobalt exposure has been associated with the development of occupational asthma, 

pneumoconiosis (a restrictive lung disease caused from inhaling dust), heart problems, and 

allergic contact dermatitis [Sjogren et al. 1980; Gheysens et al. 1985; Walters et al. 2012].

Some studies have shown that low levels of cobalt can lead to a decrease in lung function 

[Rehfisch et al. 2015]. Other study findings indicate that skin exposure to cobalt and other 

sensitizing chemicals may lead to an asthma-like response [Sjogrens et al. 1980; Arrandale 

et al. 2012]. About 90% of absorbed cobalt is eliminated rapidly within a few days; about 

10% is eliminated with a biological half-life of about 2 years [ACGIH 2001]. No information 

was found on the dermal absorption of cobalt, but skin contact with cobalt may result in a 

hypersensitivity to cobalt in a small percentage of occupationally exposed persons.

Chromium

Chromium is most often used as an alloy (ferrochrome) in stainless steel and in chrome 

plating. In addition, chromium is used in the pigment and dye, tanning, and glassmaking 

industries. Exposure to chromium can cause eye, nose, throat, and skin irritation, and may 

cause skin allergy [NIOSH 2010]. In the general population of Western countries, the average 
Health Hazard Evaluation Report 2013-0033-3238 Page 31

concentration of chromium in the urine ranges from 0.24 to 1.8 μg/L [ACGIH 2004]. The 

BEI for end-of-shift, end-of-workweek total chromium in urine is 25 μg/L. OSHA does not 

have a legal requirement for levels of urine chromium.

Hexavalent Chromium

Chromium occurs in several valence states, and hexavalent chromium is commonly used 

in industry in various paint and primer pigments, graphic art supplies, fungicides, and 

corrosion inhibitors. Hexavalent chromium is a well-established occupational carcinogen 

associated with lung cancer and nasal and sinus cancer [NIOSH 2013]. Hexavalent 

chromium is corrosive and causes chronic ulceration and perforation of the nasal septum 

and other skin surfaces [IARC 2012]. Allergic dermatitis is one of the most common effects 

of chromium toxicity among exposed workers. Since hexavalent chromium is reduced to 

trivalent chromium in red blood cells, the level of total chromium in red blood cells can be an 

indication of hexavalent chromium exposure [ATSDR 2000].

Aluminum

Chronic occupational exposure to aluminum dust above the applicable exposure limits 

may cause pulmonary fibrosis, respiratory irritation, cough, and sore throat [Smolkova and 

Nakladalova 2014].

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 

1998a; Burton et al. 2012]. 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]. Hypersensitivity 

pneumonitis is a spectrum of granulomatous, interstitial lung diseases that occur after 

repeated inhalation and sensitization to one or more of a wide variety of microbial agents 

(bacteria, fungi, or amoebae), animal proteins, and low-molecular-weight chemical antigens 

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

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 
Page 32 Health Hazard Evaluation Report 2013-0033-3238

Expert Committee on Occupational Safety recommended a health-based OEL 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 hypersensitivity pneumonitis. At this time, health data are insufficient 

to allow us to recommend a specific limit for fungal contamination in MWFs.

Noise

Noise-induced hearing loss is an irreversible condition that progresses with noise exposure. 

It is caused by damage to the nerve cells of the inner ear and cannot be treated medically 

[Berger et al. 2003]. It is estimated that more than 22 million U.S. workers are exposed 

to workplace noise levels above 85 dBA [Tak et al. 2009] and are at risk of noise-induced 

hearing loss [NIOSH 1998b]. 

Although hearing ability commonly declines with age, exposure to excessive noise can 

increase the rate of hearing loss. In most cases, noise-induced hearing loss develops slowly 

from repeated exposure to noise over time, but the progression of hearing loss is typically 

greatest during the first several years of noise exposure. Noise-induced hearing loss can result 

also from a single noise exposure or one of short duration, depending on the intensity of the 

noise and the individual’s susceptibility [Berger et al. 2003]. Noise-exposed workers can 

develop substantial hearing loss before it is clearly recognized. Even mild hearing losses can 

impair a person’s ability to understand speech and hear many important sounds. Some people 

with noise-induced hearing loss also develop “tinnitus.” Tinnitus is a condition in which a 

person perceives sound in one or both ears, but no external sound is present. Persons with 

tinnitus often describe hearing ringing, hissing, buzzing, whistling, clicking, or chirping like 

crickets. There is no cure for tinnitus. 

The preferred unit for reporting noise measurements is the dBA. A-weighting is used because 

it approximates the “equal loudness perception characteristics of human hearing for pure 

tones relative to a reference of 40 dB at a frequency of 1000 Hertz (Hz)” and is considered 

to provide a better estimation of hearing loss risk than using unweighted or other weighting 

measurements [Earshen 2003]. 

Employees exposed to noise should have baseline and yearly hearing tests to evaluate their 

hearing thresholds and determine whether their hearing has changed over time. Hearing tests 

should be done in a quiet location. In workplace hearing conservation programs, hearing 

thresholds must be measured at 500, 1000, 2000, 3000, 4000, and 6000 Hz. Additionally, 

NIOSH recommends that 8,000 Hz should also be tested [NIOSH 1998b]. The OSHA 

hearing conservation standard requires analysis of changes from baseline hearing thresholds 

to determine if the changes are substantial enough to meet OSHA criteria for a standard 

threshold shift. OSHA defines a standard threshold shift as a change in hearing threshold 

(relative to the baseline hearing measurement) of an average of 10 dB or more at 2000, 3000, 

and 4000 Hz in either ear [29 CFR 1910.95]. If a standard threshold shift occurs, then the 

company must determine if the hearing loss also meets the requirements to be recorded on 

the OSHA 300 Log of Injury and Illness [29 CFR 1904.1]. In contrast to OSHA, NIOSH 

defines a significant threshold shift as an increase in the hearing threshold level of 15 dB or 
Health Hazard Evaluation Report 2013-0033-3238 Page 33

more, relative to the baseline audiogram, at any test frequency in either ear measured twice in 

succession [NIOSH 1998b].

NIOSH has an REL for noise of 85 dBA, as an 8-hour TWA. For calculating exposure 

limits, NIOSH uses a 3-dB time/intensity trading relationship, or exchange rate. Exposure 

to impulsive noise should never exceed 140 dBA. For extended work shifts NIOSH adjusts 

the REL. When noise exposures exceed the REL, NIOSH recommends the use of hearing 

protection and implementation of a hearing loss prevention program [NIOSH 1998b]. 

The OSHA noise standard specifies a PEL of 90 dBA and an AL of 85 dBA, both as 8-hour 

TWAs. OSHA uses a less conservative 5-dB exchange rate for calculating the PEL and AL. 

Exposure to impulsive or impact noise must not exceed 140 dB peak noise level. OSHA does 

not adjust the PEL for extended work shifts. However, the AL is adjusted. OSHA requires 

implementation of a hearing conservation program when noise exposures exceed the 

AL [29 CFR 1910.95]. 
Page 34 Health Hazard Evaluation Report 2013-0033-3238

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Health Hazard Evaluation Report 2013-0033-3238 Page 37

Keywords: North American Industry Classification System 339113 (Surgical Appliances 

and Supplies Manufacturing), surgical implants, surgical device manufacturer, cobalt, 

chromium, hexavalent chromium, aluminum, metal working fluids, MWF, noise, 

respiratory, sinus, skin, Florida
Page 38 Health Hazard Evaluation Report 2013-0033-3238

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Health Hazard Evaluation Report 2013-0033-3238 Page 39

The Health Hazard Evaluation Program investigates possible health hazards in the workplace 

under the authority of the Occupational Safety and Health Act of 1970 (29 U.S.C. § 669(a)

(6)). The Health Hazard Evaluation Program also provides, upon request, technical assistance 

to federal, state, and local agencies to investigate occupational health hazards and to prevent 

occupational disease or injury. Regulations guiding the Program can be found in Title 42, Code 

of Federal Regulations, Part 85; Requests for Health Hazard Evaluations (42 CFR Part 85).

Disclaimer

The recommendations in this report are made on the basis of the findings at the workplace 

evaluated and may not be applicable to other workplaces.

Mention of any company or product in this report does not constitute endorsement by NIOSH.

Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. NIOSH is not responsible for the 

content of these Web sites. All Web addresses referenced in this document were accessible as of 

the publication date.

Acknowledgments

Analytical Support: Bureau Veritas North America

Desktop Publisher: Shawna Watts

Editor: Ellen Galloway 

Logistics: Donnie Booher and Karl Feldmann

Medical Field Assistance: Barbara MacKenzie

Availability of Report

Copies of this report have been sent to the employer, employees, and union 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. 

This report is available at http://www.cdc.gov/niosh/hhe/reports/pdfs/2013-0033-3238.pdf.

Recommended citation for this report:

NIOSH [2015]. Health hazard evaluation report: evaluation of skin and respiratory 

symptoms among employees with exposure to metals, metalworking fluids, and noise 

at an orthopedic implant manufacturer. By Beaucham C, Tapp L, Mueller C, Oza A. 

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

Control and Prevention, National Institute for Occupational Safety and Health, NIOSH 

HHE Report No. 2013-0033-3238.
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