An evaluation of 

preventive measures

at an indium-tin oxide 

production facility 

Health Hazard Evaluation Report 

HETA 2009-0214-3153 

Rhode Island 

March 2012 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health 

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific 

facility evaluated and may not be universally applicable. Any recommendations made are not to be 

considered as final statements of NIOSH policy or of any agency or individual involved. Additional HHE 

reports are available at http://www.cdc.gov/niosh/hhe/ 

Kristin J. Cummings, MD, 

MPH, Eva Suarthana, MD, 

PhD, Gregory A. Day, PhD, 

Marcia L. Stanton, BS, Rena 

Saito, PhD, Kathleen Kreiss, 

MD 
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]. 
Contents
 

RepoRt
 Abbreviations.......................................................................ii
 

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

Summary ............................................................................vi
 

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

Assessment.........................................................................6
 

Results...............................................................................15
 

Discussion .........................................................................34
 

Conclusions.......................................................................49
 

Recommendations.............................................................49
 

References.........................................................................58
 

Tables.................................................................................63
 

Figures............................................ ..................................77
 

Appendix A Historical Industrial Hygiene Sampling Data .....................81
 

Appendix B Letter to Clinic B regarding quality of chest rediographs...95
 

ACknowledgments Acknowledgements and Availability of Report...................97
 

Health Hazard Evaluation Report 2009-0214-3153 Page i 
ABBReviAtions
 

APR air-purifying respirator 

ATS American Thoracic Society 

DLCO diffusing capacity of the lungs for carbon monoxide 

EHS environmental health and safety 

ERS European Respiratory Society 

FEV1 forced expiratory volume in one second 

FVC forced vital capacity 

GA general area 

GM geometric mean 

GM-CSF granulocyte-macrophage colony-stimulating factor 

HHE health hazard evaluation 

HRCT high-resolution computed tomography 

ILO International Labour Office 

IOM Institute of Occupational Medicine 

ITO indium-tin oxide 

KL-6 Krebs von den Lungen 6 

mcg/cm2 micrograms per square centimeter 

mcg/L micrograms per liter 

MDC minimum detectable concentration 

mg/m3 milligrams per cubic meter 

mL milliliter 

MQC minimum quantifiable concentration 

NIOSH National Institute for Occupational Safety and Health 

NHANES III Third National Health and Nutrition Examination Survey 

OSHA Occupational Safety and Health Administration 

PAPR powered air-purifying respirator 

PPE personal protective equipment 

PR prevalence ratio 

PVC polyvinyl carbonate 

REL recommended exposure limit 

RPP respiratory protection program 

Page ii Health Hazard Evaluation Report 2009-0214-3153 
HigHligHts of tHe 

niosH HeAltH 

HAzARd evAluAtion 

On August 12, 2009, the National Institute for Occupational 

Safety and Health (NIOSH) received a management request for a 

health hazard evaluation at an indium-tin oxide production facility 

in Rhode Island. The company submitted the health hazard 

evaluation request because of the potential lung toxicity of indium 

compounds. Two cases of a rare lung disease, pulmonary alveolar 

proteinosis, occurred among workers at the facility in 2000 (before 

the current owner purchased the facility) and 2005. The first case 

occurred in a reclaim worker who died of his lung disease. The 

second case occurred in an indium-tin oxide department worker 

who improved with treatment. NIOSH investigators evaluated the 

preventive measures put in place by the company. 

NIOSH provided results and recommendations to the company 

in an interim report in September 2010 and to employees in 

workforce presentations in October 2010. Since that time, the 

company has continued to invest in workplace changes. In 

addition, the company has met with NIOSH on several occasions 

to discuss a potential long-term collaboration. This final report 

reflects the findings reported in the 2010 interim report. 

What NIOSH Did 

●	 NIOSH staff toured the facility on April 7-9, 2010. 

●	 We interviewed production managers, safety managers, and 

current and former workers. 

●	 We interviewed healthcare providers and technicians 

involved in medical testing conducted for the company.
 

●	 We reviewed the company’s timeline of workplace changes. 

●	 We reviewed results of air and surface sampling conducted by 

the company. 

●	 We reviewed personnel information and results of medical 

testing conducted for the company. 

●	 We interpreted pulmonary function test results using 

comparisons to U.S. adults.
 

●	 We classified chest X-rays for dust-related changes using an 

international system. 

●	 We measured air concentrations of indium and dust in four 

work areas. 

●	 We provided feedback to the healthcare providers and 

technicians to improve the quality of their medical tests.
 

Health Hazard Evaluation Report 2009-0214-3153	 Page iii 
 

 

 

HigHligHts of tHe 

niosH HeAltH 

HAzARd evAlution 

(Continued) 

What NIOSH Found 

●	 Since acquiring the facility in 2002, the company made 

extensive workplace changes.
 

●	 Changes included improved ventilation, isolation of 

processes, introduction of enclosures on machines, and a 

comprehensive respiratory protection program. 

●	 From 2004 to 2010, the company conducted 13 air sampling 

surveys and several surface sampling surveys. 

●	 Indium air levels exceeded 0.1 milligrams per cubic meter 

throughout the facility and were highest in the refinery and 

reclaim areas. NIOSH recommended an exposure limit of 

0.1 milligrams per cubic meter before indium lung disease 

was discovered. There is no exposure limit set by regulation. 

●	 Indium air levels did not appear to change over time, 

although the small number of samples and variations in 

sampling methods make it hard to compare results.
 

●	 The company established a comprehensive medical 

surveillance program, which included annual blood indium 

level, spirometry, lung volumes, and diffusing capacity. 

Chest X-rays were conducted periodically, but not annually. 

●	 Some current and former workers had abnormalities on 

medical tests suggesting work-related health effects. These 

include: 

o	 21 (50%) had blood indium concentration greater 

than 5 micrograms per liter after hire. In Japan, 

doctors have found indium-related lung effects at 3 

micrograms per liter and greater. 

o	 Restriction (small lungs) on spirometry after hire 

was several times more common than in the general 

U.S. adult population. 

o	 Some workers had an abnormal fall in an important 

lung function measurement during employment. 

o	 Some workers tested had abnormally low gas 

exchange after hire. 

o	 Although test quality was lower than desired, the 

abnormalities could not be explained by test quality. 

Abnormalities were as common in good quality 

tests as in lower quality tests. 

●	 Workers in areas with high indium exposures did not always 

have more lung abnormalities, suggesting that different types 

of indium have different risks. For instance: 

o	 Workers in the refinery had higher levels of 

indium in the air and in their blood, but few lung 

abnormalities. 

Page iv	 Health Hazard Evaluation Report 2009-0214-3153 
 

 

HigHligHts of tHe 

niosH HeAltH 

HAzARd evAlution 

(Continued) 

o	 Workers in the indium-tin oxide department had 

lower levels of indium in the air and in their blood, 

but more lung abnormalities. 

●	 Workers hired from 2007 to 2009 had lower blood indium 

concentrations and fewer lung function abnormalities 

than workers hired before 2007, suggesting the company’s 

workplace changes have had a positive impact on exposure 

and health. 

What Managers Can Do 

●	 Control dust migration from production processes. 

●	 Develop procedures to protect workers during upset 

conditions with potentially high exposures to indium 

compounds.
 

●	 Improve the respiratory protection program including proper 

use, cleaning, maintenance, and storage of respirators. 

●	 Continue efforts to further lower exposures to indium 

compounds.
 

●	 Continue to monitor workers’ health with periodic medical 

testing. 

●	 Continue to monitor exposures with periodic exposure 

assessments.
 

●	 Enlist NIOSH’s assistance to obtain high-quality medical 

testing and comprehensive assessment of exposure. 

What Employees Can Do 

●	 Follow workplace practices intended to reduce exposure to 

indium compounds. 

●	 Wear personal protective equipment such as a respirator as 

instructed by your employer. 

●	 Participate in medical testing and air sampling offered by 

your employer. 

●	 Participate in any medical testing or air sampling offered by 

NIOSH in the future. 

●	 Report new chest symptoms such as shortness of breath 

to your employer’s health and safety official, the physician 

conducting medical testing for the company, and your 

personal physician. 

●	 Call NIOSH at (800) 232-2114 for questions or more 

information. 

Health Hazard Evaluation Report 2009-0214-3153	 Page v 
summARy
 

Air levels of indium 

exceeded the NIOSH 

recommended exposure 

limit throughout the 

facility and workers had 

abnormalities on medical 

tests consistent with 

health effects related 

to indium compounds. 

Workers hired more 

recently had lower blood 

indium concentrations 

and fewer lung function 

abnormalities, suggesting 

the company’s efforts 

have had a positive 

impact on exposure and 

health. We agreed with 

the company’s proactive 

approach to prevention 

that includes ongoing 

workplace improvements 

and more frequent 

medical surveillance and 

made recommendations 

for additional steps, which 

could include a long-term 

collaboration between the 

company and NIOSH to 

understand and prevent 

lung disease related to 

indium compounds. 

On August 12, 2009, the National Institute for Occupational 

Safety and Health (NIOSH) received a management request for 

a health hazard evaluation (HHE) at an indium-tin oxide (ITO) 

production facility in Rhode Island. The company submitted 

the request because of the potential lung toxicity of indium 

compounds. The request was for an evaluation of the preventive 

measures put in place by the company. 

To conduct the evaluation, NIOSH staff reviewed and analyzed 

industrial hygiene and health data provided by the company and 

healthcare providers, and reviewed supporting documents provided 

by the company. From April 7 through 9, 2010, we visited the 

facility to conduct interviews with managers and workers, tour the 

facility, collect bulk samples, and conduct limited air sampling. 

We also visited the current pulmonary function laboratory and met 

with members of the current healthcare provider team at a local 

hospital. 

For historical industrial hygiene data, we grouped samples by type 

and work area, calculated average values, and examined trends over 

time. We compared average values to the NIOSH recommended 

exposure limit (REL) of 0.1 milligrams per cubic meter (mg/m3

). 

Notably, NIOSH recommended this exposure limit before indium 

lung disease was discovered. There is no exposure limit set by 

regulation. 

For historical health data, we evaluated test quality, classified 

results using updated reference equations, calculated frequencies 

of abnormalities, and examined trends over time. We examined 

associations between abnormalities and worker characteristics such 

as employment status, hire date, job title category, blood indium 

concentration, and estimated indium exposure from the industrial 

hygiene data. 

We found that, since acquiring the facility in 2002, the company 

made extensive workplace changes. These changes included 

ventilation enhancements, isolation of processes, introduction of 

enclosures on machines, a comprehensive respiratory protection 

program, and a comprehensive medical surveillance program. 

Records from 13 air sampling surveys that were conducted between 

2004 and mid-2010 were provided to NIOSH. We did not find a 

clear trend in indium concentrations over time. Indium air levels 

exceeded 0.1 mg/m3 throughout the facility and were highest in the 

refinery and reclaim areas. 

Page vi Health Hazard Evaluation Report 2009-0214-3153 
summARy (Continued) 

Records from 57 workers who participated in the medical 

surveillance program from 2002 to mid-2010 were provided to 

NIOSH. We found that some current and former workers had 

abnormalities on medical tests suggesting work-related health 

effects. For instance, more than half of those tested had blood 

indium concentration greater than 5 micrograms per liter (mcg/L) 

after hire. This is important because in Japan, doctors have found 

indium-related lung effects at 3 mcg/L and greater. Restriction 

on spirometry after hire and excessive decline during employment 

in forced expiratory volume in 1 second (FEV1

) (a lung function 

measurement made using spirometry) were more common than 

expected. These findings are important because restriction on 

spirometry can be a sign of lung disease and excessive decline 

in FEV1 can be an early marker of lung disease; both have been 

documented in workers who developed severe lung disease while 

working with indium compounds. In addition, some workers 

tested had abnormally low total lung capacity and some had 

abnormally low diffusing capacity, both of which can be signs of 

lung disease. Although test quality was lower than desired, the 

high prevalence of abnormalities could not be explained by test 

quality. The prevalence of abnormalities was as high in good 

quality tests as it was in lower quality tests. 

Workers in areas with higher indium exposures tended to have 

fewer lung abnormalities than workers in areas with lower indium 

exposures. This finding suggests that different types of indium 

have different health risks and that indium air concentration 

alone is an inadequate measure of exposure. More sophisticated 

sampling and analytic methods that account for differences among 

indium compounds are needed. 

Workers hired more recently had lower blood indium 

concentrations and fewer lung function abnormalities, suggesting 

the company’s efforts have had a positive impact on exposure and 

health. However, lung function abnormalities among workers 

hired more recently remained higher than expected, indicating 

a need for continued exposure reduction measures and ongoing 

medical surveillance. 

In a September 2010 interim report, we recommended further 

lowering of exposures through engineering controls, keeping 

indium compounds confined so that they don’t contaminate 

other areas, and proper use, maintenance, and storage of personal 

protective equipment, including powered air-purifying respirators. 

Health Hazard Evaluation Report 2009-0214-3153 Page vii 
 

summARy (Continued) 

We also recommended the use of consistent methods for air 

sampling, more frequent medical surveillance for newly hired 

workers, and improvements to the sensitivity and quality of the 

medical tests included in the surveillance program. Since that 

time, company officials have met in person with NIOSH officials 

and staff on two occasions to discuss a potential long-term 

collaboration to obtain high-quality and commercially unavailable 

medical testing and comprehensive exposure assessments including 

an engineering controls evaluation. In November 2011, the 

company provided NIOSH with an update on workplace changes 

that had been introduced since 2010 or were planned for the near 

future. This update made clear that the company anticipated and/ 

or incorporated many of the recommendations we made into its 

ongoing preventive efforts. 

Keywords: NAICS 331419 (Primary Smelting and Refining 

of Nonferrous Metal [except Copper and Aluminum]), indium, 

indium oxide, indium tin oxide, interstitial lung disease, 

pulmonary alveolar proteinosis, lung function tests, spirometry, 

restriction. 

intRoduCtion	 On August 12, 2009, NIOSH received a management request 

for an HHE at an ITO production facility in Rhode Island. The 

company submitted the HHE request because of the potential 

lung toxicity of indium compounds. The HHE request was for an 

evaluation of the preventive measures put in place by the company. 

NIOSH provided results and recommendations to the company 

in an interim report in September 2010 and to employees in 

workforce presentations in October 2010. Since that time, the 

company has continued to invest in workplace changes. In 

addition, the company has met in person with NIOSH staff on 

two occasions to discuss a potential long-term collaboration. This 

final report reflects the information contained in the 2010 interim 

report. 

ITO is a sintered material typically consisting of 90% indium oxide 

(In2O3) and 10% tin oxide (SnO2) [Medvedovski et al. 2008]. 

ITO is used in the manufacture of such devices as liquid crystal 

displays, touch panels, solar cells, and architectural glass. In these 

applications, a thin coating of ITO provides the dual properties 

of electrical conductivity and optical transparency. Sputtering, a 

process in which ITO ceramic tiles or “targets” are bombarded with 

energetic particles that atomize the material, is used to deposit a 

Health Hazard Evaluation Report 2009-0214-3153	 Page 1 
intRoduCtion (Continued) 

thin film of ITO on the surface of interest. Exposures to indium 

compounds (including indium hydroxide [In(OH)3

], indium oxide, 

and ITO) may occur during ITO production, ITO use for the 

creation of thin films, and reclamation in countries including the 

United States, Japan, China, Taiwan, and the Republic of Korea. 

There is a growing literature indicating adverse health effects 

related to ITO. From 2003 to 2010, ten cases of symptomatic 

lung disease, including two deaths, were reported among workers 

in Japan, the United States, and China [Omae et al. 2011]. The 

cases occurred throughout the ITO industry, spanning the entire 

lifecycle of ITO production, use, and reclamation. One case 

occurred in an indium oxide production facility, where ITO 

exposure would not be expected. The affected workers were young 

(median age at diagnosis of 35 years), with relatively short time 

from hire to diagnosis (median length of 6 years). Symptoms 

included shortness of breath and cough that did not improve away 

from work. At an international workshop convened by NIOSH in 

2010, expert clinicians identified alveolar proteinosis, cholesterol 

clefts, cholesterol granulomas, and interstitial fibrosis as common 

features of the cases; emphysema was noted in more than half of 

the cases [Cummings et al. 2011]. 

The workshop participants suggested that exposure to indium 

compounds causes a new lung disease that may progress from 

alveolar proteinosis (filling of the lung’s air sacs with surfactant, a 

mixture of protein and lipid) to fibrosis (scarring of the lung tissue) 

and emphysema (destruction of the lung tissue) [Cummings et al. 

2011]. These findings are consistent with the results of animal 

studies that have demonstrated alveolar proteinosis and pulmonary 

fibrosis following exposure to a variety of indium compounds 

including indium oxide and ITO [Leach et al. 1961; National 

Toxicology Program 2001; Tanaka et al. 2002; Lison et al. 2009; 

Lison and Delos 2010; Tanaka et al. 2010; Nagano et al. 2011]. 

Two of the reported cases, including one death, occurred at the 

Rhode Island ITO production facility that is the subject of this 

report [Cummings et al. 2010a]. Both affected workers were 

diagnosed with pulmonary alveolar proteinosis, a rare lung disease 

that is typically considered of unknown cause (idiopathic), but 

occasionally occurs in association with other diseases or following 

occupational dust exposures [Trapnell et al. 2003; Ioachimescu 

and Kavuru 2006]. In pulmonary alveolar proteinosis, the lung’s 

air sacs fill up with surfactant, a mixture of protein and lipid made 

Page 2 Health Hazard Evaluation Report 2009-0214-3153 
intRoduCtion (Continued) 

by the lung’s cells. The excess surfactant impairs gas exchange, 

the movement of oxygen and carbon dioxide between the lung 

and the blood. Most patients with pulmonary alveolar proteinosis 

have symptoms of shortness of breath and cough, although nearly 

a third of patients in one large series had no symptoms [Trapnell 

et al. 2003; Ioachimescu and Kavuru 2006; Inoue et al. 2008]. 

Pulmonary function tests can be normal, but they typically show 

restrictive pattern on spirometry, mildly reduced lung volumes, 

and more dramatically reduced diffusing capacity, reflecting the 

impaired gas exchange [Trapnell et al. 2003]. Chest radiography 

can show a variety of patterns [Ioachimescu and Kavuru 2006]. 

The first case of pulmonary alveolar proteinosis at the Rhode 

Island facility occurred in a reclaim worker and preceded the 

current owner’s 2002 purchase of the facility [Cummings et al. 

2010a]. His tasks included crushing used targets and production 

waste materials by hand or machine and operating a hydrogenfueled reduction furnace that has since been eliminated. He was 

hired in 1999, developed symptoms approximately nine months 

after hire, and was diagnosed with pulmonary alveolar proteinosis 

in 2000. Despite treatment, he developed radiographic fibrosis 

(scarring of the lungs) and died of respiratory failure in 2006. 

The second case was in a worker in the ITO department, where 

ITO targets are made from indium oxide and tin oxide powders. 

His tasks included sanding unfired castings and deburring 

sintered targets. He was hired in January 2004 and developed 

intermittent recurrent symptoms of cough, shortness of breath, 

and chest tightness, approximately six to nine months after hire. 

He did not seek care for the symptoms, attributing them to the 

common cold. In September 2005 he experienced a workplace 

inhalational exposure that led to an evaluation by a pulmonologist 

and a diagnosis of pulmonary alveolar proteinosis. He did not 

return to work after the inhalational exposure. He had clinical and 

radiographic improvement after treatment with whole lung lavage, 

but remains limited in his activities by his lung disease. 

In idiopathic pulmonary alveolar proteinosis, autoantibodies 

against granulocyte/macrophage colony-stimulating factor (GMCSF) lead to impaired alveolar macrophage function and decreased 

surfactant clearance [Trapnell et al. 2003]. In the second case 

at this facility, autoantibodies against GM-CSF were detected 

in the worker’s blood, raising the possibility of an autoimmune 

mechanism associated with exposure to indium compounds 

Health Hazard Evaluation Report 2009-0214-3153 Page 3 
intRoduCtion (Continued) 

[Cummings et al. 2010a; Costabel and Nakata 2010; Cummings et 

al. 2010b]. 

There are several reasons to conclude that these two cases of 

pulmonary alveolar proteinosis were related to exposures occurring 

during ITO production at this facility. First, there is temporality: 

exposure preceded disease. Exposure was confirmed in both cases 

by the detection of indium in lung tissue samples [Cummings et al. 

2010a]. Second, pulmonary alveolar proteinosis is quite rare, with 

an annual incidence of less than 0.5 per million persons [Seymour 

and Presneill 2002; Inoue et al. 2008]. Thus, the occurrence by 

chance of two cases in a single facility’s small workforce is highly 

unlikely. Third, there is consistency and specificity between 

exposure to indium compounds and this rare health outcome. A 

third case of pulmonary alveolar proteinosis occurred in a Chinese 

worker exposed to ITO during production of liquid crystal 

displays for cellular telephones [Xiao et al. 2010]. Furthermore, 

pathologists participating in the international workshop at NIOSH 

found histopathological evidence of alveolar proteinosis in nearly 

all cases of lung disease in workers exposed to indium compounds, 

regardless of the initial diagnosis [Cummings et al. 2011]. Fourth, 

there is coherence between epidemiologic and laboratory findings, 

in that multiple experimental studies have demonstrated alveolar 

proteinosis in animals exposed to indium compounds [Leach et al. 

1961; National Toxicology Program 2001; Lison and Delos 2010; 

Nagano et al. 2011]. 

Workplace investigations in Japan have revealed that published 

cases occurred against a background of subclinical or undiagnosed 

lung disease in co-workers. At the Japanese ITO production facility 

in which five of the published cases occurred, 108 current and 

former workers underwent high resolution computed tomography 

(HRCT) of the chest; 23 (21%) had significant interstitial changes 

and 14 (13%) had significant emphysematous changes [Chonan 

et al. 2007]. Notably, only seven (30%) of the 23 with interstitial 

changes on HRCT had abnormalities on conventional radiography 

(chest X-ray). A positive correlation existed between serum indium 

concentration and both degree of radiographic abnormalities and 

serum level of the mucin-like glycoprotein Krebs von den Lungen 

6 (KL-6), a marker of interstitial lung disease [Kobayashi and 

Kitamura 1995]. In addition, percent predicted values of total lung 

capacity and diffusing capacity of the lungs for carbon monoxide 

(DLCO) decreased with increasing quartile of serum indium. A 

cross-sectional study of 93 indium-exposed and 93 non-exposed 

Page 4 Health Hazard Evaluation Report 2009-0214-3153 
intRoduCtion (Continued) 

workers in ITO manufacturing and recycling plants in Japan 

demonstrated exposure-response relationships between serum 

indium concentrations and serum markers of lung inflammation 

such as KL-6 and surfactant proteins (SP)-A and SP-D [Hamaguchi 

et al. 2008]. 

A subsequent multi-center study of nearly 600 current and former 

indium workers from 13 indium production, recycling, and 

research facilities included the workers described by Chonan et al. 

[2007] and Hamaguchi et al. [2008] [Nakano et al. 2009]. Among 

current workers, exposure-response relationships between serum 

indium and KL-6 were observed at serum indium values exceeding 

2.9 mcg/L and between serum indium and SP-D at serum indium 

values exceeding 4.9 mcg/L. Spirometric abnormalities were 

more common at the highest serum indium concentrations. 

Similar trends were seen in former workers, who were noted to 

have exposure-response relationships between serum indium and 

interstitial abnormalities on HRCT. In addition, concentrations 

of serum indium and serum markers of lung inflammation were 

significantly lower in workers who were hired after improvements 

in the work environment had been implemented, compared to 

those working before improvements. A more recent study of 

nine current workers and five former workers who manufactured 

indium ingots provided evidence that plasma indium 

concentrations reflect long-term exposure and remain elevated 

years after exposure cessation [Hoet et al. 2011]. 

In the years prior to the HHE request, the company in Rhode 

Island responded proactively to information that exposures 

occurring during ITO processing may cause lung toxicity. The 

company initiated periodic air sampling aimed at identifying 

areas with higher indium exposures, introduced controls in the 

workplace aimed at reducing airborne exposures, and established a 

medical surveillance program to closely monitor health indicators 

in the workforce. 

Process Description 

The facility has been in operation since the late 1990s under 

previous ownership and since mid-2002 under the current owner. 

The following section describes the process as of April 2010. 

The facility processes indium metal and tin oxide into ITO ceramic 

tiles or “targets” used by customers for sputtering applications. In 

Health Hazard Evaluation Report 2009-0214-3153 Page 5 
 

intRoduCtion (Continued) 

addition, indium metal is reclaimed from used targets that are 

returned to the facility by customers and from waste materials 

generated in the production process. Waste materials include 

cuttings, grindings, rejected castings and targets, and dusts 

collected from ventilation and recovery systems. 

Figure 1 shows the major steps in the production of ITO targets 

and reclamation of indium. The process begins in the refinery, 

where indium hydroxide powder is produced from solid indium 

metal by addition of acid. The indium hydroxide is then converted 

to indium oxide powder by calcination. In the ITO department, 

indium oxide and tin oxide along with other compounds are mixed 

together. The resulting liquid substance (“slip”) is cast using a 

pressurized system into molds for hardening. The castings are 

dried, undergo limited cutting and sanding, and then are fired. 

After firing, the now-sintered targets are further ground and cut to 

customers’ specifications in the grinding area. Final deburring is 

done by hand in the ITO department. 

In the reclaim area, spent targets returned from customers and 

waste materials are converted to indium metal. These materials 

are first broken down into a powder, transferred via a closed duct 

system, blended, loaded into crucibles, and heated in a reduction 

furnace. Molten metal is then cast into ingots. To reclaim 

additional indium metal, furnace drosses are subjected to further 

heating followed by chemical dissolution in glass-lined reactors 

located in the refinery. 

Additional information on process controls is found in the Results 

section under Industrial Hygiene Evaluation: Workplace Changes. 

Assessment	 To conduct our evaluation, we collected, reviewed, abstracted, 

and analyzed industrial hygiene and health data provided by the 

company and healthcare providers. We also reviewed supporting 

documents provided by the company. These supporting 

documents included a list of jobs by production area, a timeline of 

workplace changes from 2002 to 2009, a current facility map, the 

Employee Handbook, material safety data sheets, and the facility’s 

written respiratory protection program (RPP). We conducted 

telephone interviews with company production and environmental 

health and safety (EHS) managers and healthcare providers. 

From April 7 through 9, 2010, we visited the facility. During our 

visit, we conducted interviews with managers and with current 

Page 6	 Health Hazard Evaluation Report 2009-0214-3153 
Assessment (Continued) 

and former workers. These interviews were intended to provide us 

with a more complete understanding of the process, the workplace 

changes, and the medical surveillance program. We toured the 

facility, collected bulk samples, and conducted limited air sampling. 

We also visited the current pulmonary function laboratory and met 

with members of the current healthcare provider team at a local 

hospital. Below are more detailed descriptions of the industrial 

hygiene and medical evaluations. 

Industrial Hygiene Evaluation 

Review of Historical Records 

On multiple occasions from 2004 to 2010, the company 

conducted personal and general-area (GA) air monitoring to 

evaluate exposures to dust (total, inhalable, and respirable) and 

metals (indium, tin, and tin oxide) in several different work areas, 

including the refinery, ITO department, grinding area, and reclaim 

area (Table 1). Samples for airborne total dust were collected 

using closed-faced, three-piece 37-mm cassettes with either mixed 

cellulose ester filters or polyvinyl carbonate (PVC) filters. Samples 

for airborne inhalable and respirable particles were collected 

using Institute of Occupational Medicine (IOM) stainless steel 

samplers fitted with a foam dust plug and 10-mm stainless steel 

cyclones. On one occasion four samples were collected using 

4-stage impactors equipped with PVC filters to study particle size 

distributions in the grinding area, the reclaim area, and the ITO 

department. Most dust samples were analyzed for indium and 

some were also analyzed for tin or tin oxide. Surface wipe samples 

were collected in 2005 and 2007 and were analyzed for indium. 

All samples collected by the company were submitted to the same 

analytical laboratory over the entire time period. The company 

hired three consultants to conduct exposure assessments in select 

work areas throughout the facility in 2004, 2008, and 2010; these 

results were also included in our data analyses. 

The analytical methods used by multiple laboratories differed 

slightly, including associated reporting limits. Some analytical 

results reported by the laboratories were less than reporting limits 

(i.e., the minimum masses that could be confidently measured). 

Our approach for treating these values was to divide values 

determined for the minimum quantifiable concentrations in air 

(MQC) by a factor of two. MQCs were calculated by dividing 

the reporting limit by the volume of air for a given sample. The 

Health Hazard Evaluation Report 2009-0214-3153 Page 7 
Assessment (Continued) 

air samples submitted for gravimetric analysis of total, inhalable, 

and respirable dust concentrations were analyzed using NIOSH 

Methods 0500 and 0600 [NIOSH 2003]. Tin and indium 

concentrations were determined by atomic absorption and/or 

inductively coupled plasma atomic emission spectrometry using 

Occupational Safety and Health Administration (OSHA) Methods 

ID-121 and/or ID-125G [OSHA 2002a, 2002b]. The impactor 

samples were analyzed using the State of California Method 501 

[State of California 1990]. A laboratory used by one consultant in 

2008 analyzed samples using in-house methods based on NIOSH 

Methods 0500, 0600, and 7303. 

The company’s international EHS manager initially calculated ITO 

concentrations stoichiometrically by multiplying indium results by 

1.86. He later learned that this conversion factor was unreliable 

and may not accurately represent exposures; therefore, ITO 

concentrations were not reported after March 2007. As such, we 

focused our review of sampling data provided by the company on 

dust measurements (total, inhalable, and respirable) and indium 

and tin concentrations. 

NIOSH Industrial Hygiene Survey 

During our visit to the facility, we interviewed workers to obtain 

more detailed descriptions of their potential exposures during 

routine work activities, their use of personal protective equipment 

(PPE), and changes to their job tasks over time. We interviewed 

the company’s international EHS manager who conducted the air 

sampling to obtain more information about sampling methods, 

devices, and locations. We also conducted workplace observations, 

including identification of major tasks involved in each operational 

area and job title and determination of exposure control methods, 

such as ventilation, dust suppression by wet-grinding, and use of 

PPE. 

On April 8, 2010 we conducted air sampling at the facility. 

Our sampling strategy included the collection of samples for 

determination of concentrations of total dust, respirable dust, 

indium, and tin. Additionally, we collected airborne dust samples 

and bulk samples of materials used in various processes throughout 

the facility for the evaluation of physical and chemical properties. 

Full-shift GA air samples were collected from four work areas: 

refinery, reclaim area (blending room), grinding area, and ITO 

Page 8 Health Hazard Evaluation Report 2009-0214-3153 
Assessment (Continued) 

department. Total dust samples were collected using open-faced, 

three-piece 37-mm cassette samplers (Omega Specialty Products 

Division, SKC, Inc., Eighty Four, PA) loaded with PVC filters. 

Respirable dust samples (i.e., particles equal to or less than ~4 

micrometers in diameter) were collected using cyclones (MSA, 

unknown distributor) mounted onto closed-faced, two-piece, 

37-mm cassette samplers loaded with 37-mm, 5-μm pore size, preweighed PVC filters. Real-time dust measurements for particles 

equal to or less than ~10 micrometers in diameter were measured 

using PersonalDataRAM® model pDR-1000AN/1200 (Thermo 

Electron Corporation, Franklin, MA). Samples were submitted 

to the laboratory for gravimetric analysis of total and respirable 

dusts using NIOSH Methods 0500 and 0600 and for subsequent 

inductively coupled plasma atomic emission spectrometry analyses 

of tin and indium using NIOSH Method 7303 [NIOSH 2003]. 

Additional respirable samples were collected using cyclones 

mounted onto closed-faced, two-piece, 37-mm cassette samplers 

loaded with polycarbonate filters for analysis by scanning electron 

microscopy, but due to technical difficulties, these analyses were 

not completed and are not reported in the Results section. 

Medical Surveillance Evaluation 

To describe health trends in the workforce, we reviewed medical 

surveillance records and chest radiographs of the company’s 

current and former workers. Demographic data (name, date 

of birth, start date as temporary employee prior to hire by the 

company, hire date, job title, and termination date) were provided 

by the company. Medical records were obtained from the 

following healthcare providers: Clinic A, which conducted medical 

surveillance for the company until late 2007; Clinic B, which has 

conducted medical surveillance for the company since late 2007; 

the laboratories associated with these clinics; and consulting 

pulmonologists. In some cases, workers have sought care for 

possible work-related lung disease outside of the surveillance 

program; such records were reviewed when possible. We included 

in our analyses the results of questions on respiratory health and 

the following clinical tests: blood indium level, spirometry, static 

lung volumes, diffusing capacity, and chest radiography. To clarify 

the procedures used, we contacted the laboratories that conducted 

the test of blood indium level and the pulmonary function tests. 

Questionnaire 

Questions on respiratory health were from OSHA Respirator 

Health Hazard Evaluation Report 2009-0214-3153 Page 9 
Assessment (Continued) 

Medical Evaluation Questionnaire (available at: http:// 

www.osha.gov/pls/oshaweb/owadisp.show_document?p_ 

table=STANDARDS&p_id=9783) and were self-administered in 

the context of respirator clearance. We focused on chest symptoms 

that, while non-specific, could indicate lung disease: shortness of 

breath, cough, and chest pain. 

Blood Indium Level 

Blood indium level was determined by the same diagnostic 

laboratory throughout the surveillance period. The laboratory 

used inductively coupled plasma mass spectrometry to determine 

indium concentration. The lowest calibrator used was 5 mcg/L, 

and the laboratory did not report concentrations below this 

value. We determined the number of participants who ever had 

blood indium concentrations greater than or equal to 5 mcg/L 

during the surveillance period. We calculated the mean and range 

of indium concentrations of the most recent after-hire tests by 

worker characteristics. Tests with a value of “none detected” were 

assigned half of the lowest calibrator value, or 2.5 mcg/L, for these 

calculations. 

Spirometry 

Spirometry measures the volume of air that can be inhaled and 

exhaled. We examined spirometry reports to assign a quality grade 

on the basis of American Thoracic Society/European Respiratory 

Society (ATS/ERS) criteria of acceptability and repeatability [Miller 

et al. 2005]. A grade of “A” represents the highest quality while a 

grade of “F” represents the lowest quality (Table 2). A grade of A 

or B indicates a test had at least three curves that were acceptable 

and repeatable. A grade of C indicates a test had at least two 

curves that were both acceptable and repeatable. A grade of D 

indicates a test had one curve that was acceptable. A grade of F 

indicates a test did not have a curve that was acceptable. According 

to the ATS/ERS, an unacceptable curve may still be usable (such as 

for FEV1

) if it has a good start [Miller et al. 2005]. 

Spirometry reports from Clinic A’s laboratory contained sufficient 

information for grading purposes. Spirometry reports from Clinic 

B’s laboratory contained insufficient information for grading 

purposes. We requested and received from that laboratory the 

results of each expiratory effort that comprised the testing session, 

allowing us to assign a quality grade. We subsequently scored the 

grades (A=4, B=3, C=2, D=1, and F=0) and calculated the average 

quality score for each clinic. 

Page 10 Health Hazard Evaluation Report 2009-0214-3153 
Assessment (Continued) 

We limited our primary analyses to tests with at least one 

acceptable curve (quality grade of A, B, C, or D). To explore the 

effect of spirometry quality on interpretation, we also conducted 

analyses in which we included tests with no acceptable curve 

(quality grade of F). For spirometric classification, we selected 

the largest forced vital capacity (FVC) and FEV1

 from the testing 

session. We compared these volumes to reference values generated 

from 7,429 asymptomatic participants of the Third National 

Health and Nutrition Examination Survey (NHANES III) 

[Hankinson et al. 1999]. We defined obstruction as FEV1

/FVC 

ratio and FEV1

 below their respective lower limits of normal (5th 

percentiles) with a normal FVC. We defined a restrictive pattern 

as normal FEV1

/FVC ratio with FVC below the lower limit of 

normal. We classified tests with FEV1

/FVC ratio, FEV1, and FVC 

below their respective lower limits of normal as having a mixed 

pattern. Obstruction on spirometry can be seen with conditions 

such as asthma, emphysema, and chronic bronchitis. A restrictive 

pattern on spirometry can be seen with conditions such as 

interstitial lung disease and pulmonary alveolar proteinosis, as well 

as non-pulmonary conditions such as obesity and neuromuscular 

disorders. A mixed pattern can be consistent with the presence of 

both obstructive and restrictive conditions in the tested individual, 

but more commonly reflects obstruction with hyperinflation in the 

absence of true restriction [Dykstra et al. 1999]. Among the ten 

reported cases of lung disease in indium oxide and ITO workers, 

normal, obstructive, and restrictive patterns occurred [Cummings 

et al. 2011]. 

For workers who had more than one spirometry test session, we 

also examined the change in FEV1

 over time. After adults achieve 

their maximum lung volume in their mid-20s, they lose an average 

of about two tablespoons (30 milliliters (mL)) of lung volume every 

year for the remainder of their lives (if they do not smoke or have 

other exposures that injure the lungs). We defined excessive decline 

in FEV1 as a greater than expected decrease in FEV1

 between any 

two spirometry tests. The expected decrease in FEV1

 was based on 

the results of a large study of working males [Wang et al. 2006]. To 

determine cut-offs for excessive decline, we used the lower limit of 

normal (5th percentile) values shown in Table 3 [Wang et al. 2006]. 

Thus, for a test interval of 2 years, a decline greater than 12.2% 

(6.1% per year times 2 years) would be classified as excessive. We 

compared the observed to expected proportion of workers with 

excessive decline in FEV1

 using the chi-square goodness of fit test. 

Health Hazard Evaluation Report 2009-0214-3153 Page 11 
Assessment (Continued) 

We also examined changes in FEV1 over time using NIOSH’s 

Spirometry Longitudinal Data Analysis (SPIROLA) Software 

(http://www.cdc.gov/niosh/topics/spirometry/spirola-software. 

html). SPIROLA uses the limit of longitudinal decline, which 

takes into account expected within-person variation in FEV1 

and the duration of follow-up to determine whether or not an 

individual’s decline in FEV1

 may be excessive. After examining 

the sensitivity of within-person variation settings to detect a fall of 

500 mL/year in one of the index cases [Cummings et al. 2011], we 

used the default setting of 4%. We compared the agreement of the 

Wang et al. 2006 criteria and SPIROLA by calculating the kappa 

statistic. 

Total Lung Capacity 

Determining a lower than expected total lung capacity can confirm 

lung restriction suggested by a restrictive pattern on spirometry. 

The pulmonary function laboratory associated with Clinic A 

did not measure total lung capacity. The pulmonary function 

laboratory associated with Clinic B measured static lung volumes 

using helium dilution. We examined static lung volume reports 

and compared total lung capacity to reference values generated 

from a stratified random sample of the general population of an 

entire state [Miller et al. 1983]. We defined restriction as total lung 

capacity below the lower limit of normal (5th percentile). 

Diffusing Capacity 

DLCO is a measure of gas transfer in the lungs, and is reduced 

in interstitial lung diseases, pulmonary alveolar proteinosis, and 

emphysema. The pulmonary function laboratory associated with 

Clinic A did not measure diffusing capacity. The pulmonary 

function laboratory associated with Clinic B has measured DLCO 

using the single breath technique. We examined diffusing capacity 

reports for quality on the basis of ATS criteria of acceptability and 

repeatability [Macintyre et al. 2005]. Diffusing capacity reports 

from Clinic B’s laboratory contained insufficient information to 

evaluate quality. We requested and received from the laboratory 

results of each effort that comprised the testing session, allowing 

us to assess the tests’ quality. We compared the average of single 

breath DLCO values to reference values generated from a stratified 

random sample of the general population of an entire state [Miller 

et al. 1983]. We defined low diffusing capacity as DLCO below the 

lower limit of normal (5th percentile). 

Page 12 Health Hazard Evaluation Report 2009-0214-3153 
Assessment (Continued) Chest Radiography 

We classified chest radiographs according to the International 

Classification of Radiographs of Pneumoconiosis published by the 

International Labour Office (ILO) [ILO 2002]. This classification 

system allows physicians to describe the degree of dust-related 

changes present on a chest radiograph. NIOSH grants B Reader 

approval to physicians who pass an examination of proficiency in 

the ILO classification system. 

Profusion, or concentration, of small opacities is divided into four 

major categories (0, 1, 2, and 3), each of which is subdivided into 

three minor categories, for a total of 12 possible minor profusion 

categories. We judged category 0 films as having no evidence of 

dust-related changes (normal), and categories 1 through 3 have 

increasing degrees of abnormalities consistent with dust-related 

changes. 

The system also includes a description of radiograph quality: 

Grade 1 (Good, free of technical imperfections or artifacts), 

Grade 2 (Acceptable, without technical defects or artifacts likely to 

impair classification), Grade 3 (Acceptable, with technical defects 

or artifacts but still adequate for classification), and Grade 4 

(Unreadable, unacceptable for classification). 

Clinic A used traditional film radiography and provided original 

films to us. Clinic B used digital radiography and provided 

electronic copies to us. For our analyses, we required at least 

two independent B readings for each radiograph. As part of 

the medical surveillance program, radiographs from Clinic A 

had already undergone one B reading, which we used in our 

analyses. Radiographs from Clinic B had not been interpreted 

by a B Reader, as digital standards were not yet available from the 

ILO. Therefore, for these radiographs, we chose B Readers who 

were involved in NIOSH’s transition to use of digital imaging for 

detection of pneumoconiosis [NIOSH 2008]. 

Two B readings of a radiograph were considered to agree when: a) 

they identified the same major category of small opacity profusion 

or b) were within one minor category of each other, with the 

exception of interpretations that spanned the first two major 

categories (0 and 1), which were considered to disagree (normal 

and abnormal, respectively). When two B readings agreed, we 

assigned the B reading with the higher category to the radiograph. 

Radiographs with B readings that disagreed underwent an 

Health Hazard Evaluation Report 2009-0214-3153 Page 13 
Assessment (Continued) 

additional independent reading by a third B Reader. If two of the 

three B readings agreed, we used those two B readings and assigned 

the B reading with the higher category to the radiograph. If all 

three B readings disagreed, we assigned the B reading with the 

median category to the radiograph. 

Statistical Analyses 

The adverse health outcomes were: chest symptoms; abnormal 

spirometric classification; excessive decline in FEV1

; restriction 

by static lung volume measurement; low diffusing capacity; and 

abnormal radiograph. Blood indium concentration of 5 mcg/L 

or greater served as a surrogate adverse health outcome. We 

calculated frequencies of adverse health outcomes and examined 

patterns over time. In addition, we used logistic regression 

to explore associations between adverse health outcomes 

and participants’ employment status (current versus former 

workers), hire date (prior to 2007 versus 2007-2009), job title 

category (Production jobs: ITO grinder, ITO operator, reclaim 

operator, and refinery operator; other jobs: other jobs with some 

exposure, other jobs with minimal exposure), and blood indium 

concentration (below 5 mcg/L versus 5 mcg/L or greater) using 

contingency tables. We chose 2007 as a cut-point for hire date, as 

many of the workplace changes were completed by the end of 2006 

and blood indium values suggested exposures before and after 

2007 differed. The two “other jobs” categories were developed 

with management input and were meant to reflect relative indium 

exposure, on the basis of time spent in production and reclamation 

areas and tasks involved. Other jobs with some exposure were 

process control technician, laboratory technician, maintenance 

electrician, maintenance technician, and plant electrician. Other 

jobs with minimal exposure were mould maker, mould maker 

assistant, shipper/receiver, production planner/scheduler, 

health and safety manager, engineering manager, and controller. 

Management indicated that most workers did not change jobs 

during employment. In the few cases where a worker had changed 

jobs, we assigned the worker to the job title with the higher indium 

exposure for our analyses. 

We compared the proportions of the company’s workers with 

obstruction and a restrictive pattern on the most recent spirometry 

test to the proportion expected from a nationally representative 

survey. Specifically, we determined prevalence ratios (PRs) of 

obstruction and restrictive pattern on most recent after-hire 

Page 14 Health Hazard Evaluation Report 2009-0214-3153 
Assessment (Continued) 

spirometry from comparisons with the U.S. adult population 

prevalence reported in NHANES III [Department of Health and 

Human Services 1996] using indirect standardization for race 

(white, black, or Mexican-American), sex, age (17-39 years or 40­

69 years), cigarette smoking status (ever or never), and body mass 

index (normal, overweight, or obese). When smoking status was 

not available, we made the conservative assumption that the worker 

was an ever smoker. For our analyses, a PR is the ratio of observed 

to expected prevalence of obstruction or restrictive pattern. A 

PR greater than 1 indicates higher than expected prevalence of 

obstruction or restrictive pattern among the company’s workers, 

while a PR less than 1 indicates lower than expected prevalence of 

obstruction or restrictive pattern among the company’s workers. 

All data included in analyses were double-entered into a Microsoft 

Access database and reviewed for consistency. Analyses were 

conducted using SAS software Version 9.2 (SAS Institute Inc., 

Cary, NC). We considered p≤0.05 to be statistically significant. 

Identifying information was maintained in accordance with the 

Federal Privacy Act, 5 U.S.C. § 552a, as amended. 

Results
 Below we provide the results of our evaluation, which reflect 

conditions in the facility up to mid-2010. Additional information 

provided by the company to NIOSH on conditions in the facility 

after mid-2010 is found at the end of this report. 

Industrial Hygiene Evaluation 

Workplace Changes 

From 2002, when the company acquired the facility, to 2010, 

when we visited, the company completed various changes in the 

workplace aimed at exposure reduction. Changes include, but are 

not limited to, installation of new ventilation filtration devices 

(i.e., baghouses), process enclosures, and equipment. Prior to 

the implementation of these changes, the reclaim area utilized a 

hammer mill and jaw crusher to break up materials before being 

blended in a cement mixer. Both the hammer mill and jaw crusher 

were replaced by a different type of mill in an enclosed room. 

Crushed material from the mill is now transferred via a closed 

system to a separate blending room. Both rooms (i.e., milling and 

blending) are kept under negative pressure using a dedicated local 

exhaust ventilation system. Also in the reclaim area, the company 

eliminated the use of a hydrogen-fueled reduction furnace. 

Health Hazard Evaluation Report 2009-0214-3153 Page 15 
Results (Continued) 

Other improvements throughout the facility designed to reduce 

exposures include door flaps and new enclosed grinders in the 

grinding area, a high-speed door in the refinery, a downdraft table 

in the inspection room of the ITO department, and tacky mats 

placed outside of the doors of production and non-production 

areas. The company also implemented an RPP and associated 

training. According to the company’s written RPP, workers in 

fusible casting, the grinding area, maintenance, refinery, the 

reclaim area, and the ITO department are exposed to respiratory 

hazards including metal fumes, oxide dusts, particulate, and 

vapors. In the year prior to our visit, the company instituted a zero 

tolerance policy for non-compliance with respiratory protection 

requirements. During our evaluation, managers reported that two 

workers’ employment had been terminated on the basis of noncompliance with these requirements. 

Historical Industrial Hygiene Sampling 

We reviewed the company’s air sampling data collected on 13 

occasions from 2004 to 2010. A total of 84 personal samples (63 

cassettes, 16 IOMs, and 5 cyclones), 30 area samples (25 cassettes, 1 

IOM, and 4 impactors), and 19 surface wipe samples were collected 

over the entire period. It is important to note that many samples 

of each type were collected for the purpose of estimating dust 

and/or metal concentrations during short-duration, task-specific 

activities and that not all sample types were analyzed for both dust 

and metals. Appendix A contains more detailed information on 

the historical industrial hygiene sampling data. 

Personal Air Sampling 

Personal sampling results provided exposure estimates for dust 

(total, inhalable, and respirable), indium, and tin by work area. All 

exposure estimates varied throughout the facility. 

Dust

A total of 62 total dust cassette samples were collected from 

2004 to 2010 in the refinery, reclaim area, grinding area, and 

ITO department. The majority of samples representative of 

partial- to full-shift exposures were collected from 2007 to 2009 

(n=37). Results indicated that the geometric mean (GM) total dust 

concentration was highest in the refinery (2.1 mg/m3

; range = 0.68 

to 6.4 mg/m3

; n = 4). GM total dust concentrations were lower in 

the reclaim area (1.2 mg/m3

; range = 0.22 to 5.2 mg/m3; n = 10) 

Page 16 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

and lowest in the grinding area (0.36 mg/m3; range = 0.20 to 0.85 

mg/m3

; n = 8) and the ITO department (0.24 mg/m3; range = 0.05 

to 0.89 mg/m3

; n = 15). 

Inhalable dust samples (i.e., IOM samplers) were not collected in 

all years or work areas. Two inhalable dust samples were collected 

in the reclaim area in 2005 (3.8 and 13.7 mg/m3

). In the grinding 

area, 4 samples collected in 2005 and 2006 ranged from 0.05 

mg/m3

 to 1.1 mg/m3. In the ITO department, 3 inhalable dust 

samples collected in 2005 and 2006, ranged from 0.4 mg/m3

 to 1.6 

mg/m3

. 

Respirable dust samples (i.e., cyclones and IOMs) were not 

collected in all years or work areas. Two cyclone samples were 

collected in the grinding area in 2005, both resulting in respirable 

dust concentrations of 0.22 mg/m3

. Nine IOM samples were 

collected in the reclaim area, grinding area, and ITO department, 

ranging from 0.05 mg/m3

 to 2.1 mg/m3. The highest GM 

respirable dust concentration was in the reclaim area. 

Indium

A total of 63 samples were collected for total indium throughout 

the sampling period but not in all work areas in all years. Results 

of 38 partial- to full-shift samples indicated that GM total indium 

concentrations were highest in the refinery (1.5 mg/m3

; range = 

0.47 to 3.6 mg/m3

; n = 5), lower in the reclaim area (0.74 mg/m3; 

range = 0.06 to 4.0 mg/m3

; n = 10), and lowest in the grinding 

area (0.17 mg/m3

; range = 0.07 to 0.45 mg/m3; n = 8) and the ITO 

department (0.13 mg/m3

; range = 0.03 to 0.59 mg/m3; n = 15). 

Two inhalable indium samples were collected in 2005 from the 

reclaim area and the grinding area resulting in concentrations of 

3.3 mg/m3

 and 0.41 mg/m3, respectively. 

Respirable indium samples (i.e., cyclones n=4 and IOM samplers 

n=9) were collected in 2005 and 2006. Cyclone samples were 

collected in 2005 in the reclaim area and the grinding area. 

The sample collected in the reclaim area resulted in a respirable 

concentration of 0.27 mg/m3

, and in the grinding area the 

concentrations ranged from 0.0004 to 0.11 mg/m3

. GM respirable 

indium concentrations resulting from the 9 IOM samples (reclaim 

area n= 2, grinding area n=4, ITO department n= 3) ranged from 

0.01 to 1.1 mg/m3

, with the highest concentration in the reclaim 

area (0.35 mg/m3

). 

Health Hazard Evaluation Report 2009-0214-3153 Page 17 
Results (Continued) Tin

Forty-two samples were collected for total tin from 2006 to 2010, 

although not in all work areas. Results of 30 samples were used to 

evaluate exposures most representative of partial- to full-shift tin 

exposures. Results indicated that GM total tin concentration was 

highest in the reclaim area (0.02 mg/m3

; range = 0.002 to 0.12 mg/ 

m3

; n = 8). GM total tin concentrations were lower in the grinding 

area (0.01 mg/m3

; range = 0.005 to 0.02 mg/m3; n = 7) and lowest 

in the ITO department (0.003 mg/m3

; range = 0.0005 to 0.03 mg/ 

m3

; n = 12) and refinery (0.001 mg/m3; range = 0.0008 to 0.003 

mg/m3

; n = 3). 

Eight respirable tin samples (i.e., IOM) were collected in 2005 and 

2006. Concentrations ranged from 0.001 to 0.89 mg/m3

, with the 

highest concentrations in the reclaim area. 

General-Area Air Sampling 

Area sampling results provided estimates of dust (total, inhalable, 

and respirable), indium, and tin concentrations in three general 

work areas (reclaim area, grinding area, and ITO department). 

Dust

Twenty-five total dust samples (i.e., cassettes) were collected in 

2005, 2006, and 2010 in the reclaim area, the grinding area, 

and the ITO department. Four of the 25 samples were of short 

duration and were, therefore, not used in our calculation of means. 

Results indicated that GM total dust concentrations were highest 

in the reclaim area (1.2 mg/m3

; range = 0.16 to 6.6 mg/m3; n = 5), 

lower in the grinding area (0.20 mg/m3

; range = 0.05 to 0.85 mg/ 

m3

; n = 13), and lowest in the ITO department (0.04 mg/m3; range 

= 0.02 to 0.14 mg/m3

; n = 3). 

Indium

Twenty-five total indium samples were collected in 2005, 2006, 

and 2010 in the reclaim area, the grinding area, and the ITO 

department. Again, we excluded four of these samples from our 

calculation of means because they were short-duration. GM total 

indium concentrations were highest in the reclaim area (0.45 mg/ 

m3

; range = 0.02 to 4.5 mg/m3; n = 5), followed by the grinding 

area (0.03 mg/m3

; range = 0.002 to 0.45 mg/m3; n = 13), and the 

ITO department (0.01 mg/m3

; range = 0.009 to 0.02 mg/m3; n = 

3). 

Page 18 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) Tin

Ten samples were collected for total tin in 2005, 2006, and 2010 

in the reclaim area, the grinding area, and the ITO department. 

One sample was of short duration and was excluded from our 

calculation of means. The GM total tin concentrations were 

highest in the reclaim area (0.02 mg/m3

; range = 0.001 to 0.37 mg/ 

m3

; n = 4), lower in the grinding area (0.01 mg/m3; range = 0.007 

to 0.02 mg/m3

; n = 2), and lowest in the ITO department (0.001 

mg/m3

; range = 0.0009 to 0.001 mg/m3; n = 3). 

Impactor Sampling 

The particle size distribution results from the four samples 

collected in 2005 using 4-stage cascade impactors varied by 

operational area. By mass, less than 20% of total airborne 

particulate was respirable (~16% in the grinding area, ~10% in the 

ITO sanding room, and 3% in the reclaim area). ~

Surface wipe samples 

Surface wipe samples were collected in 2005 and 2007 from 

various surfaces in the facility including tables in the lunch 

room, lockers in the men’s locker room, seats inside workers’ 

personal cars, exhaust ventilation equipment on the roof, and 

inside respirator masks. Table 4 details the calculated indium 

concentrations from the surface wipe sample results. 

Trends in total indium and total dust 

concentrations over time 

From 2006 through mid-2010, 38 personal air samples were 

collected in the refinery, the reclaim area, the grinding area, 

and ITO department to estimate partial- to full-shift total 

indium exposures. Overall, the GM total indium and total dust 

concentrations were 0.29 mg/m3

 and 0.52 mg/m3, respectively. 

Refinery

A total of 23 personal samples were collected for total indium in 

the refinery from 2004 to 2009. The majority of those samples 

were of short duration (n = 18), with results indicating total indium 

concentrations of 3.3 mg/m3

 in 2004 (n = 9), 3.4 mg/m3 in 2006 

(n = 2), 0.85 mg/m3

 in 2007 (n = 6), and 0.49 mg/m3 in 2008 (n 

= 1). The remaining 5 samples, collected over partial or full shifts, 

resulted in measurements of 1.2 mg/m3

 in 2007 (n = 3), 1.1 mg/ 

Health Hazard Evaluation Report 2009-0214-3153 Page 19 
Results (Continued) 

m3 in 2008 (n = 1), and 3.6 mg/m3 in 2009 (n = 1). Although the 

short-duration total indium measurements appear to indicate a 

downward trend and the partial- to full-shift measurements appear 

to indicate an upward trend, the numbers of samples collected by 

year are too few to discern a clear upward or downward pattern. 

Reclaim Area

Eleven personal samples were collected in the reclaim area from 

2007 to 2010. Most of those samples were collected over partial to 

full shifts, results indicating GM total indium concentrations of 

1.4 mg/m3

 in 2007 (n = 3), 0.53 mg/m3 in 2008 (n = 3), 3.3 mg/ 

m3

 in 2009 (n = 2), and 0.1 mg/m3 in 2010 (n = 2). One shortduration sample, collected in 2008 resulted in a concentration of 

0.10 mg/m3

. There is no clear upward or downward trend in these 

measurements. 

Grinding Area

Eleven personal samples were collected in the grinding area from 

2006 to 2009. Eight of those samples were collected over partial 

to full shifts, results indicating GM total indium concentrations of 

0.19 mg/m3

 in 2007 (n = 3), 0.17 mg/m3 in 2008 (n = 1), and 0.15 

mg/m3

 in 2009 (n = 4). Three short-duration samples, collected in 

2006 and 2007, resulted in measurements of 0.16 mg/m3

 (n = 1) 

and 0.26 mg/m3

 (n = 2), respectively. There is no clear upward or 

downward trend in these measurements. 

Indium-Tin Oxide Department

Eighteen personal samples were collected in the ITO department 

from 2006 to 2010. Fifteen of those samples were collected over 

partial to full shifts, with results indicating GM total indium 

concentrations of 0.25 mg/m3

 in 2006 (n = 1), 0.13 mg/m3 in 

2007 (n = 5), 0.15 mg/m3

 in 2008 (n = 5), 0.01 mg/m3 in 2009 (n = 

3), and 0.07 mg/m3

 in 2010 (n = 1). Three short-duration samples, 

all collected in 2007, resulted in a GM concentration of 0.23 mg/ 

m3

. Among these samples, there appears to be a slight downward 

trend in total indium concentrations across all years. 

General area samples were collected in the reclaim area, the 

grinding area, and the ITO department in 2005, 2006, and 2010. 

The majority of partial- to full shift samples (18/21) was collected 

in 2005, which does not allow for evaluation of trends. 

Page 20 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) Workplace Observations 

During our visit to the facility, we observed two saws in the older 

part of the grinding area that were not enclosed. We did not 

observe these saws operating. When operated, these saws would 

be expected to generate a fine mist into the workplace air and 

cause the operator to come into contact with the cutting fluid, 

a water-soluble synthetic compound. We also observed that the 

door separating the sanding room from the casting area in the ITO 

department was not closed during the sanding of fired tiles. 

The company’s RPP document contains detailed information 

on respirator use, cleaning, maintenance, and storage. The 

company’s Employee Handbook makes few references to 

respiratory protection, but contains an appendix (Appendix 

2) that outlines respirator requirements by job operation. We 

noted some inconsistencies in respirator requirements between 

the RPP document and Appendix 2 of the Employee Handbook, 

which may reflect more recent updates to the RPP document. 

Also, respiratory protection was not included in the Employee 

Handbook’s list of safety equipment furnished by the company. 

We observed workers using respirators throughout the facility. 

These observations included: the use of disposable particulate 

respirators (dusk masks) in the grinding area and the refinery and 

by a maintenance worker in the reclaim area; the use of full-face 

air-purifying respirators in the sanding room and in the mixing 

area of the ITO department; and the use of powered air-purifying 

respirators (PAPR) in the reclaim area during material break-down, 

blending, filling of crucibles, and when skimming dross from the 

surface of molten metal. 

We observed some respirator use practices in the facility that were 

not consistent with the policies described in the RPP document. 

While a worker in the mixing area of the ITO department was 

wearing a full-face air-purifying respirator, workers without 

respiratory protection were within a distance of less than ten feet. 

In the reclaim area, workers removed their PAPRs and placed them 

on an empty crucible before ladling molten metal into casts. This 

task required one reclaim area worker to stand atop a platform 

while ladling from an open crucible; this worker did not wear a 

respirator during this task. Local exhaust ventilation was in place, 

but appeared insufficient to substantially reduce worker exposure 

to airborne metal fumes. 

Health Hazard Evaluation Report 2009-0214-3153 Page 21 
Results (Continued) 

We also observed problems with respirator storage, fit, and 

cleaning. We observed open boxes of particulate respirators 

placed within work areas. We observed a full-face air-purifying 

respirator hanging on the door knob to the sanding room. The 

respirator was later worn by a worker in the same area without 

being cleaned. In addition, it was apparent that there was not a 

proper seal between the mask and the worker’s face. We were told 

that respirators are stored in cabinets within each work area, which 

could lead to contamination of the respirators during storage. We 

did not observe an area designated for respirator cleaning. 

We understood from conversations with company management 

that the use of latex or nitrile gloves was required in some 

workplace areas, specifically in the ITO department and in 

the grinding area. Indeed, we observed some workers in those 

production areas who wore these types of gloves. In the ITO 

department, we observed that one worker’s glove was torn. 

Additionally, we learned that some workers wore gloves because 

of what they described as a tendency for infection to occur when 

cuts or abrasions on the skin were contaminated by dusts in the 

workplace. 

During our time at the facility, we observed an upset condition 

in which the closed duct system in the reclaim area was damaged 

and a cloud of dust outside of the blending room resulted. At the 

time of the incident, no one in the immediate area was wearing 

respiratory protection. Company management did not remove 

employees or themselves from the affected area at the time of the 

incident despite visible dust in the air and accumulation of dust on 

the floor. Workers and managers did not don respirators during 

this event. We were told that this was not the first time that there 

had been an upset condition in this area. 

We were told during interviews with company management and 

workers that showering is only mandatory for reclaim area workers. 

However, in the Employee Handbook, item 15 of the plant safety 

rules list states that all workers in the ITO department, the reclaim 

area, low melting alloy casting, or the refinery are required to 

shower at the end of their shift. 

NIOSH General Area Air Sampling 

Air samples that we collected in April 2010 from the refinery 

(samplers located beside the sieve machine), ITO department 

Page 22 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

(center of the ITO room), grinding area (near the partially enclosed 

grinder), and the reclaim area (inside the blending room) revealed 

total dust concentrations ranging from 0.049 mg/m3

 to 0.272 

mg/m3

 and respirable dust concentrations ranging from less than 

the minimum detectable concentration (MDC) in air to 0.135 

mg/m3

 (Table 5). The only total dust concentration above the 

MQC was in the reclaim area, which was 0.272 mg/m3

; total dust 

concentrations in all other areas were between the MDC (0.049 – 

0.051 mg/m3

) and MQC (0.146 – 0.152 mg/m3). Respirable dust 

concentrations in all areas were less than MQC (0.17 – 0.18 mg/ 

m3

) or MDC (0.057 – 0.061 mg/m3). 

Total indium mass concentrations ranged from 0.009 mg/m3

 (ITO 

department) to 0.136 mg/m3

 (the reclaim area); the only indium 

mass concentration that exceeded the NIOSH REL for indium 

(0.1 mg/m3

) was measured in the reclaim area. Respirable indium 

mass concentrations ranged from 0.002 mg/m3

 (refinery and the 

grinding area) to 0.042 mg/m3

 (the reclaim area). 

Both total and respirable mass concentrations of tin were less than 

the MDC (< 0.0005 mg/m3

) or the MQC (0.001 mg/m3) in all 

areas except the ITO department, where the total and respirable 

concentrations were 0.003 mg/m3

 and 0.002 mg/m3, respectively. 

Real-time Dust Measurements 

In the refinery, we placed the real-time monitor beside the sieve 

machine, an area isolated from the hallway by a wall and an 

overhead door. The door remained closed while the operator 

loaded machines. The real-time dust concentrations (Figure 2) 

ranged from 0.035 to 0.94 mg/m3

, with an average concentration 

of 0.07 mg/m3

 (duration = 513 minutes). Peak dust concentrations 

of approximately 0.45 and 0.94 mg/m3

 were observed while the 

operator loaded the calcining furnace with indium hydroxide. 

In the ITO department, the real-time monitor was located on a 

work bench in the center of the work area between casting and 

the sanding room. Approximately five employees worked in this 

area during the sampling period (509 minutes). The real-time 

dust concentrations (Figure 3) ranged from 0.018 to 0.092 mg/m3

, 

with an average of 0.031 mg/m3

. Real-time dust concentrations 

remained low throughout the sampling period with no notable 

peaks. 

Health Hazard Evaluation Report 2009-0214-3153 Page 23 
 

Results (Continued) 

In the grinding area, the real-time monitor was placed on the 

partially enclosed grinder when sampling began at 7:05AM, but 

was moved to a work bench located beside the grinder at 11:00 

AM. An operator ran the partially enclosed grinder between 

11:00AM and 11:20 AM resulting in slightly elevated dust 

concentrations. Fully enclosed saws were operated in the area 

during the entire sampling period (496 minutes). The real-time 

dust concentrations (Figure 4) ranged from 0.033 to 0.202 mg/m3

. 

The average concentration was 0.068 mg/m3

. 

In the reclaim area, the real-time monitor was placed inside the 

blending room, which was isolated from the hallway by a wall and 

an overhead door. The door remained closed while operators ran 

machines inside the room. Real-time dust concentrations (Figure 

5) ranged from 0.007 to 8.26 mg/m3

, with an average of 0.168 

mg/m3

. The highest concentration was observed when an upset 

condition occurred at 7:21 AM, resulting in a cloud of dust outside 

of the blending room. The upset condition was caused when a 

hole developed at the elbow of the closed transfer system ducting. 

The operators resumed the process at 8:21AM and completed 

two batches during the 478 minutes sampling period. There were 

periodic peak concentrations of approximately 0.25 mg/m3

 every 

70 minutes, but due to the lack of observation during the entire 

sampling period, we cannot identify the task(s) associated with 

these peaks. 

Additional Samples 

Table 6 provides information on the 11 bulk samples that 

we collected for future physicochemical characterization and 

toxicological studies. 

Medical Surveillance Evaluation 

The medical surveillance program evolved over time as new 

diagnostic tests were added. The company’s corporate medical 

director provided input into the program’s content. Most recently, 

the change in providers from Clinic A to Clinic B occurred so that 

the company could include additional pulmonary function testing 

(i.e., measurements of total lung capacity and diffusing capacity) 

not available from Clinic A. Medical surveillance was mandatory 

for all workers and managers who spend time in production areas 

and was available to others (such as laboratory workers) who work 

with indium outside of production areas. Annual surveillance 

included questions about respiratory health, blood indium level, 

Page 24 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

spirometry, static lung volumes, and diffusing capacity. Chest 

radiography was conducted periodically, but not annually. The ten 

workers we interviewed understood that medical surveillance was 

in place because indium is a potential lung toxin, but none was 

aware that cases of lung disease (pulmonary alveolar proteinosis), 

including a fatality, had occurred in his workplace. 

Results and recommendations were provided by Clinic B’s 

physician to the individual worker and to the company’s regional 

EHS manager. Abnormal surveillance results could prompt 

evaluation by a pulmonologist, which could include additional 

testing. At the time of our evaluation, workers with abnormal 

pulmonary function test and chest radiograph results were 

followed with HRCT scans of the chest every six months. When 

the physician recommended removal of the worker from any work 

area where he may be exposed to indium, job reassignment was 

arranged by the company. Reassignment could be to a different 

job within the same area, if the new job was considered not to have 

exposure. 

A total of 57 workers, all males, were hired by September 30, 2009, 

participated in some aspect of the medical surveillance program 

from May 2002 through March 18, 2010, and were included in our 

analyses. The mean age at hire was 37 years (range 19-56 years). 

Thirty (53%) were current workers and 27 (47%) were former 

workers. Thirty-one (54%) were hired prior to 2007 and 26 (46%) 

from 2007 to 2009. Most (n=52; 91%) participating workers were 

hired after the current owner’s 2002 purchase of the facility. Table 

7 shows additional characteristics of the participating workers. 

Questionnaire 

A total of 70 completed questionnaires from 54 workers had 

comparable questions on chest symptoms for analysis. Thirty-two 

workers completed a questionnaire at hire and 2 (6%) reported 

at least one chest symptom. Four (12%) of 34 workers reported 

at least one chest symptom after hire. Of 15 workers without 

reported chest symptoms on the first questionnaire (whether at 

or after hire) and an available subsequent questionnaire, 2 (13%) 

reported chest symptoms on the subsequent questionnaire. 

Blood Indium Level 

The laboratory that conducted the blood indium testing analyzed 

samples as either plasma (blood without cells but with clotting 

Health Hazard Evaluation Report 2009-0214-3153 Page 25 
Results (Continued) 

factors) or serum (blood without cells or clotting factors). Initially, 

the laboratory used 5 mcg/L as its “reporting value,” or cut-off for 

reporting a concentration of indium. Concentrations of indium 

below 5 mcg/L were reported as “none detected.” In some cases, 

a reporting value of 10 mcg/L was used, and concentrations of 

indium below 10 mcg/L were reported as “none detected.” In late 

2007, the laboratory made an “in-house administrative decision” 

to change the reporting value to 11 mcg/L. Thus, after 2007, 

concentrations of indium below 11 mcg/L were reported as “none 

detected.” 

We requested that the laboratory provide a measured 

concentration of indium for all 71 tests with a result of “none 

detected.” In response, the laboratory provided additional 

results using a reporting value of 5 mcg/L for those tests with a 

higher reporting value. For 14 tests, the laboratory was not able 

to provide results using a reporting value below 10 or 11 mcg/L 

because the samples had been diluted 1:2, the lowest calibrator had 

been dropped, or the laboratory was not able to find the test in its 

computer system using the information (name, date of birth, and 

date of test) we provided. These 14 tests were excluded from our 

analyses. In total, we identified an additional 10 tests with blood 

indium level of 5 mcg/L or greater through this request to the 

laboratory. The remaining 47 tests had a result of “none detected” 

using the reporting value of 5 mcg/L. 

Fifty-one (89%) of the participating workers underwent blood 

indium testing at least once (including tests done at hire), for 

a total of 101 tests included in our analyses. Nineteen workers 

were tested at hire and one (5%) had a blood indium level of 5 

mcg/L or greater. The available records did not indicate that this 

worker had previous indium exposure. Forty-two underwent blood 

indium testing at least once after hire. Figure 6 shows the mean 

and range of after-hire blood indium concentrations by year. In 

2005, the mean after-hire concentration was 24.1 mcg/L, while in 

2009 the mean after-hire concentration was 10.2 mcg/L. 

A total of 21 (50%) of 42 workers tested after hire had at least one 

test showing blood indium level of 5 mcg/L or greater. Figure 

7 shows the blood indium concentrations of these 21 workers 

over time. From 2004 to 2005, there were 5 workers who had 

substantial increases in blood indium concentration. From 2008 

to 2009, the increases that occurred appear more modest. 

Page 26 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

The proportion with blood indium level of 5 mcg/L or greater 

and the median concentration varied by hire date and job title 

(Table 8). Nineteen (70%) of 27 tested workers hired prior to 2007 

versus two (13%) of 15 tested workers hired from 2007 to 2009 

had at least one test showing a blood indium level of 5 mcg/L 

or greater after hire. Twenty-one (63%) of 33 tested production 

workers versus none of 9 tested other workers had at least one test 

showing a blood indium level of 5 mcg/L or greater after hire. 

Half of tested current workers and half of tested former workers 

had a blood indium level of 5 mcg/L or greater after hire. We 

used the last after-hire blood test to calculate median values. The 

median blood indium concentration was 11 mcg/L for those 

hired prior to 2007 versus 2.5 mcg/L for those hired from 2007 to 

2009. Refinery operators had the highest median blood indium 

concentration at 10 mcg/L. Both current and former workers had 

a median concentration of 3.8 mcg/L. 

Spirometry 

Clinic A interpreted spirometry tests using reference equations 

derived from a study of 697 healthy white subjects in Tucson, 

Arizona [Knudson et al. 1983]. Clinic B interpreted spirometry 

tests using reference equations derived from a study of 988 healthy 

white subjects in Northwest Oregon [Morris et al. 1971]. Below we 

report the results of our interpretations using reference equations 

derived from NHANES III [Hankinson et al. 1999], which may 

differ from interpretations using the earlier reference equations. 

Fifty-five (97%) of the workers participating in medical surveillance 

underwent spirometry testing with a total of 138 spirometry tests. 

We examined the quality of all tests (Table 9). Of 47 spirometry 

tests conducted by Clinic A, 29 (62%) had A or B grades for both 

FVC and FEV1

; 5 (11%) had F grades. The average grade was B 

for both FVC and FEV1

. Of 91 spirometry tests conducted by 

Clinic B, 16 (18%) had A or B grades for both FVC and FEV1

; 

55 (60%) had F grades. The average quality grade was D for both 

FVC and FEV1

. The most common reason that expiratory curves 

from Clinic B did not meet acceptability criteria was unsatisfactory 

exhalation, specifically lack of a volume-time plateau, suggesting 

that workers were not adequately coached to achieve maximal 

exhalation. 

Incomplete exhalation (evidenced by a lack of a volume–time 

plateau on the expiratory curve) could lead to underestimation 

Health Hazard Evaluation Report 2009-0214-3153 Page 27 
Results (Continued) 

of the FVC and an interpretation of restrictive pattern when 

lung volumes are truly normal. In examining curves that did not 

reach a volume-time plateau, we noted that the starts tended to 

be good, suggesting the tests were usable [Miller et al. 2005]. In 

addition, the curves’ slopes generally were not steep at the point 

of termination, indicating that the amount of additional volume 

that would have been recorded had a volume-time plateau been 

achieved was probably quite small. Thus, while these tests did not 

meet the strict quality criteria, our impression was that they were 

unlikely to grossly underestimate the FVC and thereby unlikely 

to lead to generally false interpretation of restrictive pattern in 

workers with normal lung volumes. To evaluate the effect of 

spirometry quality on interpretation, we examined quality grade 

and interpretation using the most recent after-hire spirometry tests 

(Table 10). When we limited the analysis to the 13 workers with 

good spirometry quality (FEV1

 and FVC of grade A or B), 5 (38%) 

had a restrictive pattern. When we included 3 workers with grade 

C quality, 5/16 (31%) had a restrictive pattern. When we included 

7 workers with grade D quality, 9/23 (39%) had a restrictive 

pattern. When we included 22 workers with grade F quality, 

14/45 (31%) had a restrictive pattern. Thus, the inclusion of tests 

with poor spirometry quality does not appear to have overestimated 

the prevalence of restrictive pattern among workers at this facility. 

In order to achieve a more representative analysis with larger 

numbers, rather than be limited to an analysis of a much smaller 

and less representative group, we present below the results of our 

interpretation of all spirometry tests regardless of quality, unless 

otherwise noted. 

Twenty-eight workers were tested at hire: 5 (18%) of these tests 

showed a restrictive pattern, 2 (7%) showed obstruction, and 21 

(75%) were normal. Forty-five workers underwent spirometry 

testing at least once after hire: 18 (40%) of these workers had 

at least one test showing a restrictive pattern after hire, 5(11%) 

had at least one test showing obstruction, and one (2%) had at 

least one test showing a mixed pattern. The proportion with a 

restrictive pattern on spirometry after hire varied by employment 

status and hire date (Table 11). Nine (33%) current workers and 

9 (50%) former workers had at least one test showing a restrictive 

pattern after hire. Thirteen (52%) workers hired prior to 2007 

and five (25%) workers hired from 2007 to 2009 had at least one 

test showing a restrictive pattern after hire. Thirteen (38%) of 

34 production workers, 4 (57%) of 7 other workers with some 

exposure, and 1 (25%) of 4 other workers with minimal exposure 

Page 28 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

had at least one test showing a restrictive pattern after hire. 

Table 12 shows the PRs (observed/expected) of restrictive pattern 

on spirometry comparing this company’s workers with the U.S. 

adult population. When all spirometry tests regardless of quality 

were included in the analysis, the prevalence of a restrictive pattern 

on spirometry among this company’s workers was 4.0 times 

the corresponding prevalence for the U.S. adult population, a 

statistically significant difference. When results were restricted to 

acceptable quality spirometry (FEV1

 and FVC of grade A, B, C, or 

D), the prevalence of a restrictive pattern on spirometry among this 

company’s workers was 5.3 times the corresponding prevalence for 

the U.S. adult population, also a statistically significant difference. 

When the results were restricted to good quality spirometry (FEV1 

and FVC of grade A or B), the prevalence of a restrictive pattern 

on spirometry among this company’s workers was 5.6 times the 

corresponding prevalence for the U.S. adult population, also a 

statistically significant difference. Thus, the inclusion of tests with 

poor spirometry quality does not appear to have overestimated 

the PRs of restrictive pattern. For these analyses, we assumed 

12 workers for whom smoking status was unavailable were ever 

smokers. PRs were similar when we assumed these 12 workers 

were non-smokers. PRs for obstruction demonstrated that the 

prevalence of obstruction among the company’s workers was not 

elevated compared to the corresponding prevalence for the U.S. 

adult population. 

Eighteen (33%) workers were tested at hire and during 

employment. Comparisons of spirometry interpretation from their 

at-hire and most recent spirometry tests (regardless of quality) are 

shown in Table 13. Of 13 workers with a normal interpretation 

at hire, 1 (8%) had obstruction and 3 (23%) had a restrictive 

pattern on the most recent spirometry. All 4 of these workers 

also had an excessive decline in FEV1

, resulting in abnormality. 

When the analyses were restricted to acceptable quality spirometry 

(FEV1

 of grade A, B, C, or D), a comparison of FEV1 from the 

baseline and last spirometry tests was possible for 7 workers. Of 

5 workers with normal interpretation at baseline, 1 (20%) showed 

a restrictive pattern on the last test. This worker also showed an 

excessive decline in FEV1

. Of two workers with a restrictive pattern 

at baseline, one had a restrictive pattern and one had a normal 

result on the last test. When the analyses were restricted to good 

quality spirometry (FEV1

 of grade A or B), the comparison of FEV1 

from the baseline and last spirometry tests was possible for only 3 

Health Hazard Evaluation Report 2009-0214-3153 Page 29 
 

Results (Continued) 

workers. Of 2 workers with normal interpretation at baseline, 1 

had a restrictive pattern and 1 had a normal result on the last test. 

The worker with the restrictive pattern on the last test also showed 

an excessive decline in FEV1

. One worker had a restrictive pattern 

at baseline but a normal result on the last test. 

Of 41 workers with at least two tests, 26 workers had normal 

interpretation on their first test (whether at or after hire). Two 

of these 26 (8%) had obstruction and 4 (15%) had a restrictive 

pattern on their last test. All 6 of these workers also had an 

excessive decline in FEV1

, resulting in abnormality. When the 

analyses were restricted to acceptable quality spirometry (FEV1

 of 

grade A, B, C, or D), a comparison of FEV1

 from the baseline and 

last spirometry tests was possible for 18 workers. Of 11 workers 

with a normal result on the first test, 2 (18%) showed a restrictive 

pattern on the last test. Both workers also had an excessive decline 

in FEV1

. Of 7 workers with a restrictive pattern on the first test, 

four had a restrictive pattern on the last test. One of these 4 had 

an excessive decline in FEV1

. When the analyses were restricted to 

good quality spirometry (FEV1

 of grade A or B), the comparison 

of FEV1

 from the first and last spirometry tests was possible for 8 

workers. Two (40%) of 5 workers with normal interpretation on 

their first test had a restrictive pattern on their last test. 

We evaluated the presence of excessive decline in FEV1

 in 41 

workers with at least two tests, where the first test was done either 

at hire or during employment (Tables 14a; Table 14b excludes five 

workers with spirometric interpretation of obstruction). A total 

of 12 (29%) ever had an excessive decline in FEV1

, significantly 

higher than expected (p<0.0001). Eight (30%) of 27 current and 4 

(29%) of 14 former workers ever had an excessive decline in FEV1

. 

Based on job category, 4 (57%) of 7 ITO grinders and 5 (33%) of 

15 ITO operators ever had an excessive decline in FEV1

. When 

the analyses were restricted to spirometry with good FVC and FEV1 

quality (“A” or “B” grade), there were 5 (50%) of 10 workers who 

ever had an excessive decline in FEV1

. When we included workers 

with grade C quality, 5/11 (46%) had an excessive decline in FEV1

. 

When we included workers with grade D quality, 5/22 (23%) had 

an excessive decline in FEV1

. Thus, the inclusion of tests with 

poor spirometry quality does not appear to have overestimated the 

prevalence of excessive decline in FEV1

. 

SPIROLA identified 10 (24%) workers with excessive decline in 

FEV1

 during employment on the basis of limit of longitudinal 

Page 30 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

decline criteria. Agreement between the two methods was 85% 

(kappa=0.63). 

Total Lung Capacity 

Lung volume testing was initiated in late 2007 by Clinic B. Thirtyseven (65%) of the workers participating in medical surveillance 

underwent lung volume testing with a total of 91 tests. Although 

we did not conduct a formal quality review, we noted that many 

of the lung volume test reports indicated an inadequate helium 

equilibration time of 0.00 minutes, calling into question the 

quality of the tests. However, when we inquired about this issue, 

the laboratory informed us that the information on the reports was 

incorrect, and the helium equilibration time was generally 2 to 3 

minutes. 

Clinic B interpreted lung volume tests using reference equations 

of Goldman and Becklake [1959]. Below we report the results of 

our interpretations using reference equations of Miller et al. [1983], 

which may differ from interpretations using the earlier reference 

equations. 

One (8%) of 12 workers tested at hire had a low total lung 

capacity, indicating restriction. Thirty-five (61%) of the 57 workers 

participating in medical surveillance underwent at least one lung 

volume test after hire (Table 15). Of these 35, 8 (23%) were 

interpreted as ever having a low total lung capacity, indicating 

restriction. A total of 7 (26%) of 27 current workers and 1 (13%) 

of 8 former workers ever had a low total lung capacity after hire. 

A total of 3 (25%) of 12 ITO operators and 2 (40%) of 5 of reclaim 

operators ever had a low total lung capacity after hire. 

The occurrence of new cases of low total lung capacity was 

evaluated in 33 workers with at least two total lung capacity 

measurements. Of 27 workers with normal total lung capacity 

on the first test (whether at or after hire), 2 (7%) had low total 

lung capacity on the last test. Of 6 workers with a low total lung 

capacity on the first test (whether at or after hire), 4 (67%) had a 

low total lung capacity on the last test (including the one with low 

total lung capacity at hire) and 2 (33%) had a normal total lung 

capacity on the last test. 

Diffusing Capacity 

Diffusing capacity testing was initiated in late 2007 by clinic B. 

Health Hazard Evaluation Report 2009-0214-3153 Page 31 
Results (Continued) 

Thirty-seven (65%) of the 57 workers participating in medical 

surveillance underwent diffusing capacity testing with a total of 91 

tests. We excluded one test effort due to poor quality. 

Clinic B interpreted diffusing capacity tests using reference 

equations of Gaensler and Wright [1966]. Below we report the 

results of our interpretations using reference equations of Miller et 

al. [1983], which may differ from interpretations using the earlier 

reference equations. 

All of 12 workers tested at hire showed a normal diffusing capacity. 

Thirty-five (61%) workers underwent at least one diffusing capacity 

test after hire (Table 16). Of these, 8 (23%) were interpreted as 

ever having low DLCO, indicating low diffusing capacity. A total 

of 5 (19%) of 27 current workers and 3 (38%) of 8 former workers 

ever had low DLCO after hire, indicating low diffusing capacity. 

A total of 2 (33%) of 6 of ITO grinders and 4 (33%) of 12 ITO 

operators ever had low DLCO after hire, indicating low diffusing 

capacity. Tests interpreted as having low diffusing capacity had 

acceptable curves and met repeatability criteria. 

The occurrence of new cases of low diffusing capacity was 

evaluated in 33 workers with at least two diffusing capacity tests. 

Of 28 workers with normal diffusing capacity on their first test 

(whether at or after hire), 2 (7%) had a low diffusing capacity on 

their last test. Of 5 workers with a low diffusing capacity on the 

first test, 3 (60%) had a low diffusing capacity on the last test and 2 

(40%) had a normal diffusing capacity on the last test. 

Co-occurrence of Lung Function Abnormalities 

Table 17a shows that 7 (44%) of 16 workers with a restrictive 

pattern on spirometry also had an excessive decline in FEV1

, 

in comparison to 5 (20%) of 25 workers without a restrictive 

pattern on spirometry. Likewise, 7 (88%) of 12 workers with an 

excessive decline in FEV1

 had a restrictive pattern on spirometry, in 

comparison to 9 (31%) of 29 workers without an excessive decline 

in FEV1

. Table 17b shows the results when five workers with 

spirometric obstruction are excluded. 

Table 17c shows that 7 (58%) of 12 workers with a restrictive 

pattern on spirometry had low total lung capacity, indicating 

restriction, in comparison to 1 (4%) of 23 workers without a 

restrictive pattern on spirometry. Likewise, 7 (88%) of 8 workers 

Page 32 Health Hazard Evaluation Report 2009-0214-3153 
Results (Continued) 

with low total lung capacity, indicating restriction, had a restrictive 

pattern on spirometry, in comparison to 5 (19%) of 27 without low 

total lung capacity. 

Table 17d shows that 3 (25%) of 12 workers with restrictive pattern 

on spirometry had a low diffusing capacity, in comparison to 5 

(22%) of 23 workers without a restrictive pattern on spirometry. 

Likewise, 3 (38%) of 8 workers with a low diffusing capacity had a 

restrictive pattern on spirometry, in comparison to 9 (33%) of 27 

workers without a low diffusing capacity. 

Table 17e shows that 2 (25%) of 8 workers with low total lung 

capacity, indicating restriction, had a low diffusing capacity, in 

comparison to 6 (22%) of 27 without a low total lung capacity. 

Likewise, 2 (25%) of 8 workers with a low diffusing capacity had 

low total lung capacity, indicating restriction, in comparison to 6 

(22%) of 27 workers without a low diffusing capacity. 

Chest Radiography 

Forty-six (81%) of the 57 workers who participated in medical 

surveillance had chest radiography as part of medical surveillance 

with a total of 64 tests. Of 31 chest radiographs conducted by 

Clinic A, 18 (58%) were Grade 1, 11 (36%) were Grade 2, and 2 

(6%) were Grade 3 quality. Of 33 chest radiographs conducted by 

Clinic B, none was Grade 1, 23 (70%) were Grade 2, and 10 (30%) 

were Grade 3 quality. The most common reasons that radiographs 

from Clinic B did not meet Grade 1 criteria were the presence of 

artifact and problems with exposure. 

None of 25 chest radiographs done at hire was abnormal. Twentyeight (48%) workers had chest radiography at least once after 

hire with a total of 39 tests. Two (7%) workers who had normal 

baseline chest radiographs had subsequent abnormal chest 

radiographs after hire that were consistent with pneumoconiosis. 

Both workers were reclaim operators hired prior to 2007 and had 

blood indium concentrations greater than 5 mcg/L after hire. 

In addition, two former workers had diffuse abnormalities on 

chest radiographs done after hire outside of the formal surveillance 

program. The first was an ITO grinder who had an excessive 

decline in FEV1

 of 700 mL in one year, five years after hire. His 

chest radiograph was interpreted by a radiologist as showing 

multiple reticulo-nodular densities throughout both lungs. He was 

Health Hazard Evaluation Report 2009-0214-3153 Page 33 
Results (Continued) 

evaluated by a pulmonologist, who thought that the abnormalities 

were likely caused by exposures at work. The pulmonologist noted 

near complete resolution of the abnormalities over the course 

of one month. We were unable to contact this former worker 

or obtain subsequent imaging studies. The second was the ITO 

operator who was ultimately diagnosed with pulmonary alveolar 

proteinosis. 

Referral to Pulmonologist 

Five (9%) of the 57 workers who participated in medical 

surveillance were referred to a pulmonologist as a result of 

abnormal findings on medical surveillance tests. The worker 

who developed pulmonary alveolar proteinosis was referred to a 

pulmonologist on account of an acute inhalational injury, rather 

than his abnormal medical surveillance results. 

Exposure-Response Relationship 

We used logistic regression to examine the association between 

a group of five adverse health effects ever after hire (restrictive 

pattern on spirometry, excessive decline in FEV1

, low total lung 

capacity, low diffusing capacity, and abnormal chest radiograph) 

and worker characteristics. Adverse health effects were not 

associated with employment status (p=0.35). Adverse health effects 

were significantly less common in workers hired more recently 

(2007-2009) than in workers hired before 2007 (p<0.01). Adverse 

health effects appeared to vary with job title, but these differences 

were not statistically significant (p=0.16), likely due to small 

numbers in subsets. Adverse health effects tended to be more 

common in workers with blood indium level of 5 mcg/L or greater, 

but these differences were not statistically significant (p=0.07). 

Table 18 summarizes estimates of exposure and adverse health 

effects by job and is discussed in detail in the Discussion section of 

this report. 

disCussion
 Context 

Lung disease related to indium compounds is an emerging health 

issue about which many questions remain. For instance, we 

know little about the exposure-response relationship. It appears 

that not only ITO but also indium oxide can cause lung disease, 

and perhaps other indium compounds encountered in the ITO 

industry. What characteristics of the responsible compounds are 

important, such as particle size, form (gas, vapor, mist, or dust), 

and concentration? Is cumulative or peak exposure relevant? 

Page 34 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) 

What influences do work processes such as mixing, spraying, and 

grinding have? We also have limited knowledge of the disease 

process. Exposures during ITO production appear to lead to one 

disease that can evolve from pulmonary alveolar proteinosis to 

fibrosis and emphysema. Why did some workers present early 

in employment and others later? Why have some cases been 

marked by inexorable progression and others by some degree of 

stabilization? What role does autoimmunity play? Is the process 

reversible with a reduction in exposure? For how long does indium 

persist in the body even after work exposure to indium compounds 

ceases, putting workers at risk through an immunologic or toxic 

mechanism? 

Given our limited and evolving understanding of lung disease 

related to indium compounds including ITO, a precautionary 

approach to prevention is warranted. This company appropriately 

introduced a preventive program aimed at reducing exposures 

throughout the facility. We found that the workplace changes have 

been extensive: ventilation improvements, machine enclosures, 

isolation and automation of processes, and required use of 

respiratory protection in some areas. Many of these changes were 

completed by the end of 2006, but others (particularly in the 

reclaim area) were more recent, and additional improvements have 

occurred (see below) and are planned. Indeed, it was clear from 

our interactions with managers that, despite the many changes 

that have already been introduced, the company sees exposure 

reduction as an ongoing process. The ultimate goal of exposure 

control is to limit potential risk of adverse health effects. 

Medical Surveillance Evaluation 

To monitor workers for adverse health effects, the company 

developed a medical surveillance program that is one of the most 

comprehensive we have reviewed. This medical surveillance 

program reflects the company’s substantial commitment to worker 

health. 

Our analyses of the medical surveillance data indicated that many 

workers had abnormalities on medical tests. We found that half 

of the workers had blood indium levels above 5 mcg/L. This level 

is concerning because a cut-off of 3 mcg/L has been suggested 

for preventing early effects of indium on the lungs [Nakano et al. 

2009]. We also found that more than 30% of the workers had a 

restrictive pattern on spirometry, which was at least 4 times more 

Health Hazard Evaluation Report 2009-0214-3153 Page 35 
disCussion (Continued) 

common than expected from comparisons with the U.S. adult 

population. Furthermore, about a quarter of the workers had an 

abnormal fall in lung volume (FEV1

) over time, beyond what would 

be expected from normal aging. In addition, about a quarter each 

had low total lung capacity and low diffusing capacity after hire, 

when we would expect no more than 5% of healthy non-smokers 

to have such abnormalities. 

What could cause this apparent disproportionate burden of lung 

function abnormalities in these workers? A restrictive pattern 

on spirometry can be seen with certain lung diseases and other 

conditions (such as obesity and neuromuscular disorders) that 

cause the lungs to be smaller than normal. In some cases, obesity 

may have been responsible for an individual worker’s restrictive 

pattern on spirometry. Yet our analyses accounted for the effects of 

weight and still found that a restrictive pattern was more common 

than expected. Furthermore, 12 workers with a restrictive pattern 

on spirometry underwent testing for total lung capacity (Table 17b). 

Of these, 7 (58%) had a low total lung capacity, indicating that 

the lungs were smaller than expected. If representative of all the 

workers with restrictive pattern on spirometry, this finding suggests 

that more than half of all of the workers with a restrictive pattern 

on spirometry truly had abnormally small lungs (restriction). 

Another possible explanation is that low test quality caused 

abnormal results. We did find that spirometry quality was much 

lower than desired; ideally, all tests would have three acceptable 

curves and be repeatable within 150 mL (quality grade A or B) 

[Miller et al. 2005]. However, in our analysis of the spirometry 

data, we did not find any evidence that low test quality influenced 

the proportion with restrictive pattern. Good quality spirometry 

had a similar proportion of tests with restrictive pattern as low 

quality spirometry. Low quality spirometry could also have 

influenced detection of abnormal fall in the volume of air blown 

out in the first second of the test (FEV1

) over time. However, the 

FEV1

 is unlikely to be affected by the most common quality issue 

we observed (lack of volume-time plateau). We did not conduct a 

formal quality review for the test of total lung capacity. We found 

that all but one of the workers with low total lung capacity had a 

restrictive pattern on spirometry (Table 17b), which is about what 

we would expect from a good quality test of total lung capacity. 

We reviewed the diffusing capacity tests for quality, and did not 

encounter quality issues in those tests that indicated a low diffusing 

capacity. Thus, we cannot readily invoke low test quality as an 

Page 36 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) 

obvious explanation for the apparent disproportionate burden of 

lung function abnormalities among these workers. 

Smoking is a well-known cause of lung disease. However, we 

cannot attribute the burden of lung function abnormalities in 

these workers to smoking. Smoking-related lung disease takes 

decades to develop, and these workers were relatively young, with 

a mean age less than 40 years at hire. In addition, unless very 

severe, smoking-related lung disease would be expected to result in 

obstruction (not a restrictive pattern) on spirometry, and would not 

be expected to cause low total lung capacity. In some individual 

workers with a low diffusing capacity but normal or elevated total 

lung capacity, smoking-related emphysema could explain the low 

diffusing capacity. However, for the vast majority of workers with 

a low diffusing capacity, smoking-related emphysema is not a 

plausible explanation due to young age, low total lung capacity, or 

relatively few years of smoking. 

Asthma is a common lung disease that could affect a relatively 

young group of workers. People with asthma have either a normal 

pattern, obstruction, or a mixed pattern (not solely a restrictive 

pattern) on spirometry. Thus, asthma does not account for our 

restrictive pattern findings. Worsening asthma could lead to an 

abnormal fall in FEV1

 over time. However, the majority (7 of 12, 

or 58%) of the workers with an excessive decline in FEV1

 had a 

restrictive pattern on spirometry, which suggests their abnormal fall 

in FEV1

 was not related to asthma. Furthermore, asthma does not 

cause low total lung capacity or low diffusing capacity, so cannot 

explain these abnormalities. 

Another possible explanation for the burden of lung function 

abnormalities in these workers is that they represent pre-existing 

conditions in workers. We did not find convincing evidence for 

pre-existing restrictive lung disease. Lung function abnormalities 

consistent with restrictive lung disease were far less common 

among workers tested at hire than among workers tested after hire. 

For instance, the prevalence of a restrictive pattern on spirometry 

was 18% in those tested at hire and 31% in those tested after hire; 

the prevalence of low total lung capacity was 8% in those tested at 

hire and 17% in those tested after hire; and the prevalence of low 

diffusing capacity was 0% in those tested at hire and 17% in those 

tested after hire. Although not all workers were tested at hire, the 

available evidence indicates that the majority of the lung function 

abnormalities were not present at hire, but appeared to develop 

during employment. 

Health Hazard Evaluation Report 2009-0214-3153 Page 37 
 

disCussion (Continued) 

There are several reasons to conclude that the burden of lung 

function abnormalities in these workers is primarily related to the 

workers’ common exposure to indium compounds. First, there 

is a temporal relationship to exposure in that most abnormalities 

followed employment. Lung function abnormalities were more 

common after hire than at hire. Excessive declines in FEV1 

occurred during employment, after exposure to indium compounds 

began. Second, the types of abnormalities we observed (restrictive 

pattern, abnormal fall in FEV1

, low total lung capacity, and low 

diffusing capacity) are all consistent with the reported health effects 

of indium compounds. Third, both blood indium levels above 5 

mcg/L and lung function abnormalities tended to be less common 

in workers hired more recently (2007 to 2009). This relationship 

is what we would expect if exposure to indium compounds both 

increases indium in the blood and causes damage to the lungs. 

We conclude that past exposures to indium compounds were 

high enough to cause adverse health effects. The proportions 

of lung function abnormalities in workers hired more recently 

(2007 to 2009) were lower than those among workers hired before 

2007, suggesting the company’s workplace changes had a positive 

impact on exposure and health. However, the abnormalities 

among workers hired more recently generally remained elevated 

(for instance, see Table 12). If these abnormalities were related 

to exposure to indium compounds, as the evidence suggests, then 

more recent exposures to indium compounds were still not low 

enough to prevent adverse health effects. 

How low must indium exposures be to prevent lung health effects? 

The existing NIOSH REL of 0.1 mg/m3

 [NIOSH 2005] for indium 

and indium compounds was introduced in the 1980s. The REL 

thus predates the reports of interstitial lung disease and pulmonary 

alveolar proteinosis in the ITO industry. As such, it should not 

be assumed to be protective against these diseases. While the 

Japanese experience with lung disease in ITO production workers 

has been the most extensive, industrial hygiene evaluations either 

have been limited [Chonan et al. 2007] or not pursued [Hamaguchi 

et al. 2008; Nakano et al. 2009] in Japanese studies. The Japanese 

government recently introduced a standard for respirable indium 

of 3 x 10-4 mg/m3

 on the basis of animal studies of indium oxide 

and ITO toxicity [Ministry of Health, Labor, and Welfare, 2010]. 

Whether this level will be protective remains to be determined. 

In the absence of a known protective exposure limit, guidance can 

be derived from observed health outcomes among the exposed 

Page 38 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) 

workforce. In effect, a safe exposure level is one at which workers 

do not develop adverse health outcomes that are reasonably related 

to indium compounds. This company’s medical surveillance 

program could be a means to determine a safe indium exposure 

limit, by examining cohorts by date of hire as the company 

continues to lower indium exposures. 

Industrial Hygiene Evaluation 

Our review of the historical sampling data found that GM 

total indium concentrations in the partial- to full-shift personal 

air samples ranged from 0.13 (ITO department) to 1.45 mg/ 

m3

 (refinery), without an observed decline over time. Among 

the partial- to full-shift area air samples, GM total indium 

concentrations ranged from .01 (ITO department) to 4.5 mg/ 

m3

 (reclaim). The GM total indium concentration in grinding 

was 0.03 mg/m3

. Chonan et al. (2007) reported an indium 

concentration of 0.05 mg/m3

 in the grinding area of a facility with 

affected workers. The area air sampling that we conducted on 

April 8, 2010 showed indium concentrations ranging from 0.009 

mg/m3

 (ITO department) to 0.136 mg/m3 (reclaim area). These 

concentrations suggest lower exposures than in the past, but may 

also reflect differences in sampling strategy and technique (such as 

our reliance on GA samples, which may underestimate exposures 

compared to personal samples) that make direct comparisons 

challenging. With only four GA air samples, our results are 

unlikely to be representative of personal exposures. 

The workers who developed pulmonary alveolar proteinosis while 

at the Rhode Island facility developed chest symptoms within 

a year of employment [Cummings et al. 2010a]. The second 

worker with pulmonary alveolar proteinosis was followed with 

spirometry and had an excessive decline in FEV1

 of 500 mL in his 

first year of employment. While little is known about the relevant 

exposure characteristics, the rapid development of disease suggests 

the possibility that peak concentrations (rather than cumulative 

exposures) may be important. 

The real-time dust monitoring that we conducted provides 

potentially crucial peak exposure information that is not captured 

by full-shift measurements. Real-time monitoring can be used 

to determine the ranges of dust concentrations throughout the 

facility, to evaluate the effectiveness of local exhaust ventilation 

systems, to evaluate work practices, and to identify potential 

Health Hazard Evaluation Report 2009-0214-3153 Page 39 
disCussion (Continued) 

sources of upset conditions. For instance, the real-time dust 

monitoring results from a sample collected from inside the 

blending room in reclaim suggested that the highest indium 

concentration occurred when a hole developed at the elbow of the 

closed transfer system ducting. This ducting was external to the 

blending room. We did not collect samples outside the room, but 

would expect the dust and indium concentrations to be higher 

than inside the enclosed room during such an event. Although 

workers mandatorily used PAPRs while inside the blending 

room when the process was operational, respirators were neither 

required nor worn when outside the blending room during this 

upset condition. In light of this upset condition, the company 

should consider implementing respiratory protection measures to 

be utilized during upset conditions to minimize peak exposures. 

One preventive measure to consider is the installation of a 

secondary containment system to capture process emissions due 

to failure of the primary system. Use of real-time monitoring is 

one way to identify peak exposures that cannot be identified using 

conventional sampling methods. 

The historical surface wipe samples indicated that indium was 

detected on multiple surfaces, including inside respirators, on 

the lunchroom table, in the locker room, and inside workers’ cars 

(Table 4). These results indicate that indium migration may create 

exposure opportunities and that exposure to indium compounds 

may occur in unexpected ways. For example, settled indiumcontaining dust on surfaces may become re-suspended in air, may 

contaminate workers’ skin and clothing, and may be transported 

off-site. Two surface wipe samples collected from the tops of 

lockers in the men’s locker room demonstrated the presence of 

indium-containing dust, with indium concentrations of 80.2 

micrograms per square centimeter (mcg/cm2

) and 101.4 mcg/ 

cm2

. Five surface wipe samples collected from the seats of workers’ 

personal cars demonstrated the presence of indium-containing 

dust; the highest concentration of 13.7 mcg/cm2

 was measured in 

a grinding area worker’s car. The presence of indium-containing 

dust in workers’ cars suggests that workers are taking these dusts 

home with them, thereby potentially putting non-workers (i.e., 

family members) at risk. During our walk-through of the facility, 

we toured the locker room, lunchroom, and break areas. We 

understand that these areas are cleaned by contract housekeeping 

staff and that company uniforms are picked up once a week for 

laundering off-site. During our visit, we observed that uniforms 

were overflowing from the laundry container onto the floor, which 

could also contribute to dust contamination and migration. 

Page 40 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) Exposure-Response Relationship 

As noted previously, the exposure-response relationship between 

indium compounds and lung disease is poorly understood at this 

time. Existing animal studies, case reports, and cross-sectional 

investigations of workplaces provide some guidance. Animal 

studies demonstrate that ITO is particularly toxic [Lison et al. 

2009], but also implicate other indium compounds, including 

indium oxide [Leach et al. 1961; American Conference of 

Governmental Industrial Hygienists 2001; National Toxicology 

Program 2001; Tanaka et al. 2002; Lison et al. 2009; Lison and 

Delos 2010; Nagano et al. 2011]. Early case reports of lung disease 

in ITO production workers focused on the task of wet surface 

grinding [Homma et al. 2003; Homma et al. 2005], but more 

recent reports describe health effects in workers who carried out 

other tasks as well, such as other ITO production tasks and tasks 

related to reclamation [Chonan et al. 2007; Cummings et al. 

2010a]. In addition, a recent case report describes lung disease 

(specifically pulmonary alveolar proteinosis) in a worker exposed 

to ITO during the production of cellular telephones [Xiao et al. 

2010]. Finally, one case occurred in an indium oxide production 

facility, where ITO exposure would not be expected [Cummings 

et al. 2011]. Such observations suggest that while risk may not 

be uniform throughout a facility, it is unlikely to be limited to a 

certain compound or production process. 

We attempted to explore the exposure-response relationship by 

examining exposures and health outcomes by job (Table 18). We 

found that indium exposure (as measured by total indium in 

historical personal air samples) was highest for refinery operators, 

followed by reclaim operators. ITO grinders and ITO operators 

had similar, lower indium exposures. Estimates were not possible 

for workers in other jobs with some exposure or other jobs with 

minimal exposure. Another potential measure of exposure is 

blood indium level. We found that blood indium levels of 5 

mcg/L or greater were common in production workers but not in 

other jobs considered to have lower exposure to indium. Indeed, 

more than half of the workers in each production job title, but 

none of the other workers, had blood indium levels of 5 mcg/L or 

greater. Estimates of exposure to indium thus seem to create two 

groups: Higher (refinery operator, reclaim operator, ITO grinder, 

ITO operator) and Lower (other some exposure, other minimal 

exposure). Using a blood test with a lower detection limit might 

enable refinement of exposure categories. 

Health Hazard Evaluation Report 2009-0214-3153 Page 41 
disCussion (Continued) 

Adverse health outcomes were most common in ITO operators 

and reclaim operators, intermediate in ITO grinders, and least 

common in refinery operators. For each measure of lung function, 

20 to nearly 50% of ITO operators and reclaim operators had 

abnormalities. Furthermore, all four abnormal chest radiographs 

and both known cases of pulmonary alveolar proteinosis were 

found among workers in these two job titles. In contrast, with the 

exception of one worker with a restrictive pattern on spirometry, 

refinery operators had no lung function abnormalities. Workers 

in other jobs with minimal exposure also had few lung function 

abnormalities. Abnormalities were more common among those 

in other jobs with some exposure. Indeed, more than half of the 

workers in other jobs with some exposure had a restrictive pattern 

on spirometry and half had low total lung capacity, comparable to 

the findings in ITO operators and reclaim operators. Estimates of 

adverse health response (low lung function results, abnormalities 

on chest radiography, and occurrence of pulmonary alveolar 

proteinosis) thus seem to suggest two groups that are somewhat 

different from those suggested by estimates of exposure: Higher 

(ITO operators, reclaim operators, other some exposure) and 

Lower (ITO grinders, refinery operators, other minimal exposure). 

If, as we demonstrated earlier, exposure to indium compounds is 

likely to be the primary cause of the adverse health outcomes in 

these workers, why do we see this apparent discrepancy between 

surrogates for exposure and health response? There are several 

possible explanations related to the limitations of the data we 

analyzed. First, the exposure data may not accurately reflect 

true exposure. The historical air samples were not collected in a 

systematic way to make estimates of exposure by job title. Rather, 

they were primarily intended to identify areas with higher indium 

concentrations and assess the local effects of workplace changes. 

Furthermore, estimates were not available for non-production jobs. 

In addition, the blood indium level reporting value of 5 mcg/L 

may not be an appropriate cut-off for determining exposure. In 

Japan, lung damage on chest imaging (HRCT) was observed in 

former indium workers with a serum indium level of 3.0-4.9 mcg/L 

[Nakano et al. 2009]. At the Rhode Island facility, the second 

worker with pulmonary alveolar proteinosis had a blood indium 

level less than the reporting value of 5 mcg/L more than a year 

into employment, yet had measureable indium in a lung tissue 

specimen [Cummings et al. 2010a]. Thus, although measured 

blood indium levels suggest that workers in non-production jobs 

did not have exposure to indium compounds, that conclusion 

Page 42 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) 

may not be correct. Second, the data may not accurately reflect 

response. Lung function tests and chest radiography were not 

always conducted at hire, limiting our ability to differentiate 

abnormalities that developed during employment (plausibly workrelated) from abnormalities present at hire (not work-related). 

Given the small numbers of workers in each job category, one 

or two workers with pre-employment abnormalities or with 

spirometry results influenced by poor quality testing could obscure 

true associations between exposure and health outcomes. Third, 

despite our efforts to accurately assign workers to job titles and 

job titles to categories, some misclassification may have occurred 

due to limited information on individual work histories and job 

exposure characteristics. 

Another consideration is that the healthy worker effect may have 

played a role [Li and Sung 1999]. The healthy worker effect occurs 

when workers who develop work-related symptoms or disease 

transfer within a plant away from a particular work area or leave 

a plant entirely. Workers remaining behind in that particular 

work area or plant are generally less susceptible and may appear 

healthier than the general population or workers in other work 

areas of the plant. The availability of medical records after 

workers left employment was limited, so it is possible that some 

workers developed adverse health effects during employment but 

left employment before undergoing annual medical surveillance 

testing, or developed adverse health effects after employment. 

It is also possible that the data do accurately reflect both exposure 

and response, but that the exposure-response relationship is more 

complex than can be understood from the available information. 

For instance, the role of autoimmunity in lung disease related 

to indium compounds is not clear. A recent report from Japan 

indicates that if autoimmunity played a role in the second case 

of indium lung disease at this plant, the mechanism of indium 

compounds’ toxicity is not exclusively autoimmune [Masuko et al. 

2011]. Lung disease with an autoimmune mechanism might occur 

at lower exposure thresholds or with peak exposures that are not 

well reflected by the historical air sampling results or blood indium 

levels. Indeed, there is evidence from other immune-mediated 

occupational lung diseases that peak exposures are most relevant 

to disease development [Leroyer et al. 1998; Klees and Ott 2000; 

Jacobs et al. 2008]. Lung disease that is not autoimmune might 

occur with higher exposures or in relation to cumulative exposures 

that build up a body burden of indium over time. Despite these 

Health Hazard Evaluation Report 2009-0214-3153 Page 43 
 

disCussion (Continued) 

limitations, it is notable that refinery operators had among the 

lowest rates of lung function abnormalities, despite the fact that 

most had blood indium levels of 5mcg/L or greater. The indium 

compounds in the refinery are distinct from those found elsewhere 

in the facility, and perhaps different indium compounds vary in 

their interactions with the lungs and the blood. However, it is also 

possible that the small number of refinery operators led us to miss 

an exposure-response relationship that would have been evident 

with a larger group of refinery operators. 

The difference in blood indium levels by hire date is also notable. 

In general, indium appears to persist in the blood long after 

exposure. One Japanese study looked at former indium workers 

who had left employment an average of 5 years before testing. 

The mean serum indium concentration was 9.63 mcg/L, which 

was similar to the mean concentration among current workers 

in the study of 8.35 mcg/L [Nakano et al. 2009]. A more recent 

study of nine current workers and five former workers who 

manufactured indium ingots provided evidence that plasma 

indium concentrations reflect long-term exposure and remain 

elevated years after exposure cessation [Hoet et al. 2011]. Thus, 

for the workers with long tenure, blood indium levels may 

reflect a legacy of past exposure that does not speak to current 

workplace conditions. By examining blood indium levels by 

hire date, we attempted to differentiate between past and more 

recent conditions. We found that 70% of workers hired before 

2007 but just 13% of those hired since 2007 had blood indium 

levels of 5 mcg/L or greater. Some of this difference may reflect 

differential testing. A total of 87% of workers participating in 

medical surveillance and hired before 2007 versus 62% of workers 

participating in medical surveillance and hired since 2007 have 

undergone blood indium testing after hire. It is also possible that 

this gap will close somewhat in the future, as the more recently 

hired workers spend more time at the facility. The change in the 

laboratory’s reporting value from 5 to 11 mcg/L also may have had 

an impact, but we accounted for this change to the extent possible 

by requesting indium concentrations regardless of reporting value 

used. Thus, the difference in blood indium levels by hire date 

appears real and suggests that exposures have indeed fallen in 

recent years. 

Detection of Adverse Health Effects 

We found that some aspects of the medical surveillance program 

Page 44 Health Hazard Evaluation Report 2009-0214-3153 
disCussion (Continued) 

may limit the company’s ability to detect lung disease at an early 

stage. The use of respiratory questions in the context of respirator 

clearance (a prerequisite for job performance) may lead to underreporting of chest symptoms within the surveillance program. 

Furthermore, respiratory symptoms may appear relatively late in 

the disease process, after a point at which abnormalities in lung 

function could be detected. Thus it is unlikely that questions 

on respiratory symptoms, particularly in the context of medical 

clearance for respirator use, can effectively detect lung disease at an 

early stage. 

The laboratory that conducts blood indium testing currently 

uses a reporting value of 11 mcg/L, and has never reported 

concentrations below 5 mcg/L. Given that Japanese authors 

have reported health effects at concentrations as low as 3 mcg/L 

[Nakano et al. 2009], a reporting value of 5 or 11 mcg/L seems 

inappropriately high. 

In addition, we found that the quality of spirometry tests 

conducted by Clinic B was low. In most cases, curves did not meet 

acceptability criteria because of lack of a volume-time plateau, 

which could underestimate FVC and lead to an interpretation of 

restrictive pattern in the absence of true restriction. Our sensitivity 

analyses did not demonstrate any obvious relationship between 

quality score and prevalence of a restrictive pattern, suggesting 

that the low quality did not generally influence interpretations of 

restrictive pattern. 

Yet spirometry quality has important implications when following 

workers’ lung function over time. A primary goal of monitoring 

indium-exposed workers with spirometry should be to detect 

changes in lung function before a substantial loss in lung function 

has occurred (i.e., typically before a restrictive or obstructive pattern 

has developed), so that steps can be taken to prevent further 

decline. For workers who already have abnormal spirometry 

(restriction, obstruction, or mixed pattern), longitudinal spirometry 

can be used to determine if lung function is declining further. 

Detecting losses in lung function over time requires high quality 

spirometry characterized by low variability from measurement 

errors [Hnizdo et al. 2010]. 

The use of outdated reference equations also is a concern. Clinic 

A and Clinic B interpreted spirometry using reference equations 

from small, homogeneous, geographically isolated populations that 

Health Hazard Evaluation Report 2009-0214-3153 Page 45 
disCussion (Continued) 

were studied decades ago and are unlikely to be representative of 

the company’s workers [Knudson et al. 1983; Morris et al. 1971]. 

The ATS [Pellegrino et al. 2005] recommends the use of spirometry 

reference equations derived from NHANES III, a nationally 

representative sample of more than 7000 subjects that included 

whites, blacks, and Hispanics [Hankinson et al. 1999]. In the 

case of medical surveillance of ITO industry workers, a particular 

concern is that the older equations are less likely than those 

derived from NHANES III to identify a restrictive pattern [Sood 

et al. 2007; Collen et al. 2008; Collen et al. 2010]. Thus the use 

of reference equations from Knudson et al. 1983 and Morris et al. 

1971 may underestimate the number of workers with spirometric 

abnormalities consistent with toxicity from indium compounds 

and limit the ability to detect lung disease at an early stage. We 

have similar concerns about the reference equations from the 

1950s and 1960s used by Clinic B for the lung volume and 

diffusing capacity tests. The staff at Clinic B’s pulmonary function 

laboratory indicated that they were in the process of obtaining new 

test equipment, which may address many of these issues. 

Another issue is that standard chest radiographs are likely to be 

an insensitive tool for detecting early changes in the lungs. In the 

Japanese study that found abnormalities consistent with interstitial 

lung disease on HRCT scan of the chest in 23 (21%) of 108 ITO 

production workers, just 7 of these had abnormalities on chest 

radiograph [Chonan 2007]. Lower quality chest radiography, as 

we found with Clinic B, will only make detection of abnormalities 

more error-prone. 

The frequency of testing must be considered in the context of 

what is known about disease latency and progression. Both of 

the workers at this facility who developed pulmonary alveolar 

proteinosis noted symptoms during the first year of employment. 

More frequent testing early in employment could facilitate 

early disease detection, and has been used in other workplace 

settings where some workers may be more susceptible to another 

occupational lung disease [Cummings et al. 2007]. More frequent 

testing of newly employed workers also serves to provide earlier 

feedback on the effectiveness of new workplace changes. 

Finally, there may be other biomarkers that would be useful for 

early detection of lung disease in these workers. Japanese authors 

reported strong associations between markers of lung inflammation 

that can be detected in the blood and serum indium concentration 

Page 46 Health Hazard Evaluation Report 2009-0214-3153 
 

disCussion (Continued) 

[Nakano et al. 2009]. Autoantibodies to GM-CSF may also have a 

role in detecting pulmonary alveolar proteinosis at an early stage. 

Indeed, 30% of patients with pulmonary alveolar proteinosis were 

asymptomatic at diagnosis but had detectable autoantibodies to 

GM-CSF in one study [Inoue et al. 2008]. Currently, the test for 

autoantibodies to GM-CSF is available only on a research basis. 

Response to Adverse Health Effects 

Despite the large number of workers with lung function 

abnormalities, few workers were referred to a pulmonologist for 

further diagnostic evaluation. It appears that referral has been 

triggered in the past when abnormalities were found on multiple 

tests, including abnormal chest radiograph. This approach may be 

reasonable in the primary care setting, when the probability of rare 

lung disease is low and hazardous exposures are absent. However, 

in the context of medical surveillance for an emerging occupational 

lung disease, a lower threshold for referral is appropriate. For 

example, the worker who developed pulmonary alveolar proteinosis 

had a 500 mL fall in FEV1

 nearly one year before his eventual 

diagnosis, which was prompted not by medical surveillance but by 

an inhalational exposure. Earlier referral to a pulmonologist may 

have led to a more prompt diagnosis and treatment, potentially 

altering the course of his disease. 

One powerful diagnostic tool available to a pulmonologist 

is HRCT of the chest. As noted earlier, the Japanese have 

demonstrated that HRCT is a more sensitive tool than chest 

radiography for detecting abnormalities that may be related to 

indium exposure [Chonan et al. 2007]. Notably, abnormalities 

on HRCT consistent with interstitial lung disease were common 

(27% prevalence) among former workers who had been away from 

exposure to indium compounds for an average of 5 years [Nakano 

et al. 2009]. Thus there is reason to expect that abnormalities 

related to indium compounds, once detected, may persist and do 

not need to be reconfirmed. The benefit of repeated, frequent 

use of HRCT (such as twice yearly) in this setting is unlikely to 

outweigh the associated radiation risk incurred [Smith-Bindman 

2010]. An alternative would be more frequent use of good quality 

pulmonary function tests to evaluate for changes over time. 

How should this company manage workers with abnormalities on 

pulmonary function tests or radiography that are consistent with 

lung disease related to indium compounds? Given our limited 

Health Hazard Evaluation Report 2009-0214-3153 Page 47 
disCussion (Continued) 

understanding of the exposure-response relationship, minimizing 

these workers’ exposures through job reassignment and use of 

personal protective equipment would be prudent. Although our 

analyses indicate that there are few locations and jobs at the facility 

that are without indium exposure, the jobs we categorized as other 

jobs with minimal exposure (mould maker, mould maker assistant, 

shipper/receiver, production planner/scheduler, health and safety 

manager, engineering manager, and controller) appear to be lowerrisk from the perspective both of indium exposure and adverse 

health outcomes. For workers with abnormalities consistent 

with lung disease related to indium compounds who cannot 

be relocated to one of these jobs, full-time use of a PAPR (with 

assigned protection factor of 1000) would be warranted throughout 

the facility. 

Open communication with workers about the risks and 

uncertainties of indium exposure is vital. The company’s efforts 

to share information about animal toxicity studies and Japanese 

reports of lung disease were laudable and were reflected in workers’ 

general knowledge about indium toxicity. However, the interviews 

we conducted with workers demonstrated that they were not aware 

of the occurrence of cases of lung disease in their own workplace. 

The sharing of such information can motivate an improved safety 

culture, including enhanced compliance with respirator use 

policies. 

Future Steps 

Since the release of the NIOSH interim report in 2010, the 

company has met in person with NIOSH on two occasions to 

discuss a potential long-term collaboration to determine the 

effectiveness of ongoing and newly introduced preventive measures. 

Such a collaboration could include high quality medical testing 

and research blood tests (KL-6, GM-CSF auto-antibodies) of the 

current workforce conducted by NIOSH and a comprehensive 

industrial hygiene evaluation to characterize representative full-shift 

and real-time exposures and better differentiate between exposures 

to various indium compounds. 

Page 48 Health Hazard Evaluation Report 2009-0214-3153 
ConClusions
 

ReCommendAtions
 

In response to information that exposures occurring during 

ITO processing may cause lung toxicity, the company has made 

extensive workplace changes and established a comprehensive 

medical surveillance program. We found that historical records 

of air sampling for indium did not demonstrate a clear trend 

in indium concentrations over time. We also found that 

some workers have abnormalities on medical tests suggesting 

work-related health effects. Workers hired more recently had 

lower blood indium concentrations and fewer lung function 

abnormalities, suggesting the company’s efforts have had a positive 

impact on exposure and health. Nonetheless, given our limited 

understanding of both the exposure-response relationship and 

the disease process, a precautionary approach that emphasizes 

further lowering of indium exposures and enhanced monitoring 

of adverse health outcomes among exposed workers is prudent. 

These recommendations were made in the interim report that 

was provided to the company in September 2010. Following 

these recommendations, we include information provided by the 

company in November 2011 on the status of its workplace changes. 

From this updated information, it is clear that the company 

anticipated and/or incorporated many of the recommendations we 

made into its ongoing preventive efforts. 

The hierarchy of controls approach is traditionally recommended 

as a strategy for creating a more healthful workplace. In this 

hierarchy, the preferred approach is to first eliminate hazardous 

materials or processes and install engineering controls to reduce 

exposure or shield workers. Until such controls are in place, or if 

they are not effective or feasible, administrative measures and/or 

personal protective equipment may be needed. 

In the case of an emerging occupational health issue such as 

potentially fatal lung disease related to indium compounds, 

we agree with the company’s comprehensive approach that has 

included multiple aspects of the hierarchy to reduce the risk 

of lung toxicity during ITO processing. We recommend these 

following additional steps as further improvements: 

Engineering Controls 

Engineering controls reduce exposures to workers by removing the 

hazard from the process or placing a barrier between the hazard 

Health Hazard Evaluation Report 2009-0214-3153 Page 49 
ReCommendAtions 

(Continued) and the worker. Engineering controls can be very effective at 

protecting workers. 

1.	 Separation and isolation of areas (migration control) 

●	 Clean and non-clean areas in the locker room 

should be separated. 

●	 The company should continue to monitor the 

effectiveness of the local exhaust ventilation in the 

reclaim area. 

●	 Given the upset condition we observed and the 

risk of its reoccurrence, routine observation and 

maintenance of the duct system in the reclaim area 

should be instituted. A back-up system to prevent 

the release of indium-containing dusts in the event 

of damage to the duct system should be considered. 

2.	 Some tasks in the reclaim area that involve metal fumes are 

carried out with limited ventilation controls and without 

respiratory protection. Given our limited understanding 

of the toxicity of different forms of indium, monitoring 

of exposures to metal fumes during tasks in the reclaim 

area and providing additional ventilation controls (and 

respiratory protection, see below) would be prudent. 

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 worker acceptance. Regular monitoring and 

reinforcement is necessary to ensure that control policies and 

procedures are not circumvented in the name of convenience or 

production. 

1.	 Housekeeping practices should be improved to minimize 

surface contamination in locker rooms, lunchroom, break 

areas, and production areas. 

2.	 Efforts to control the migration of contamination within 

individual work areas should include attention to work 

practices that prevent migration via hands, clothing, and 

shoes. Efforts to control the migration of contamination 

Page 50	 Health Hazard Evaluation Report 2009-0214-3153 
ReCommendAtions 

(Continued) between work areas should include limiting the transfer of 

tools and equipment. To avoid contamination of workers’ 

personal vehicles and home environments, showering at the 

end of the shift should be required for all indium-exposed 

workers. 

3.	 A section on emergency procedures should be added to the 

Employee Handbook detailing procedures for the immediate 

evacuation and isolation of work areas in the event of an 

upset condition. Workers with clean-up responsibilities 

should be provided with the necessary personal protective 

equipment, including but not limited to: respirators, eye 

and hearing protection, and chemical-protective clothing 

and gloves. Other workers should not re-enter the area(s) 

until an “all clear” signal has been given. 

4.	 Hazard communication – Workers need to be aware of 

the risks of occupational exposure to indium during ITO 

production and reclamation. We agree with the company’s 

recent efforts to share information about the toxicity of ITO 

and other indium compounds with workers and encourage 

the company to explore ways that results of ongoing medical 

surveillance could be communicated to workers on a regular 

(such as annual) basis. In addition, we recommend that a 

brief section on indium toxicity be added to the Employee 

Handbook. This section should define what indium 

compounds are, describe the potential hazards of handling 

and processing indium-containing compounds, and outline 

current information on exposure opportunities (i.e., 

inhalation, skin contact). This information may further 

motivate workers to recognize and avoid potential hazards 

associated with indium and reinforce the need for proper 

use of PPE, including respiratory protection. 

5.	 Whenever possible, workers with any otherwise unexplained 

abnormalities consistent with indium-related lung disease 

should be relocated to other jobs with minimal exposure. 

Such abnormalities include an excessive decline in FEV1 

or the development of any of the following: a restrictive 

pattern on spirometry, low total lung capacity, low diffusing 

capacity, or dust-related changes on chest radiograph or 

HRCT. As a precaution, relocation should occur whether a 

definitive diagnosis has or has not been made (see Medical 

Surveillance below). 

Health Hazard Evaluation Report 2009-0214-3153	 Page 51 
ReCommendAtions 

Personal Protective Equipment (Continued) 

PPE is the least effective means for controlling worker exposures. 

Proper use of PPE requires a comprehensive program and calls for 

a high level of worker 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. 

1.	 Our observations of the use and storage of respirators 

by the company’s workers indicate that workers need 

additional and ongoing training on the proper use, cleaning, 

maintenance, and storage of respiratory protection. 

This information should be included in the Employee 

Handbook. 

2.	 Respiratory protection should be added to the list in the 

Employee Handbook of safety equipment to be furnished by 

the company. 

3.	 The Respiratory Protection Program document and the 

Employee Handbook should be modified to assure that they 

both provide consistent information on respirator type and 

filter replacements requirements by job operation. 

4.	 The company should provide a proper location for the 

cleaning, maintenance, and storage of respirators. 

●	 Proper cleaning and disinfection of respirators 

requires a clean area where the respirator can 

be disassembled, washed with a mild detergent 

in warm water, rinsed in clean warm water, and 

allowed to air dry in a clean area prior to reassembly 

according to manufacturer recommendations. 

Given the work environment, respirators should be 

cleaned at the end of each shift and disinfected at 

least weekly. 

●	 Cabinets for respirator storage should be located 

outside of the work area, to prevent contamination. 

1.	 The role of skin exposure in causing indium-related lung 

disease is unknown. Nevertheless, workers should be 

encouraged to comply with the company’s current glove use 

policy. 

Page 52	 Health Hazard Evaluation Report 2009-0214-3153 
ReCommendAtions 

(Continued) 2.	 Respiratory protection should be worn in the reclaim area 

during tasks with exposure to metal fumes. 

3.	 In work areas where PAPRs are not currently used, PAPRs 

with assigned protection factor of 1000 should be made 

available to workers desiring a higher level of protection 

than required by the company. 

Industrial Hygiene Sampling 

Our review of historical sampling data revealed that sampling 

methods and reporting procedures for dust, indium, and tin 

changed over time, which made evaluation of trends challenging. 

These changes may have reflected the company’s need to answer 

different questions with different surveys. We recognize that in 

the future, novel sampling strategies may be needed to address new 

questions. Nonetheless, the inclusion in each survey of consistent 

methods for sampling and reporting dust and metal concentrations 

would facilitate monitoring of concentrations in workplace air over 

time and determination of trends. This exposure assessment may 

be critical in the future determination of health-protective exposure 

guidance. 

Medical Surveillance 

Our review of the medical surveillance program revealed that the 

current medical surveillance program is comprehensive. However, 

the program has had some problems with quality testing that have 

gone unrecognized, and the sensitivity of the blood indium test 

that has been used is limited. The following recommendations 

are primarily intended to improve (rather than expand) the 

current program, to allow the company to better detect possible 

occupational lung disease at an early stage. 

1.	 Frequency of testing – For newly hired workers, we 

recommend more frequent medical surveillance using 

lung function testing during the first year of employment. 

Until quality issues are resolved, testing of newly hired 

workers should occur at hire and at 3, 6, and 12 months of 

employment. Once high-quality testing is in place, it may be 

reasonable to eliminate testing at 3 months. 

2.	 Blood indium – Blood indium testing should be done 

Health Hazard Evaluation Report 2009-0214-3153	 Page 53 
ReCommendAtions 

(Continued) by a laboratory that is able to accurately determine the 

concentration of indium in blood using a limit of detection 

far lower than 5 mcg/L. The method used in the Japanese 

studies has a limit of detection of 0.1 mcg/L [Nakano et al. 

2009]. We understand that the only commercial clinical 

laboratory providing blood indium testing in the US is (at 

NIOSH’s request) currently updating its methodology to 

improve the limit of detection. 

3.	 Spirometry quality – Spirometry quality improvement is 

crucial for optimally valid interpretation of test results, 

particularly for longitudinal assessment of lung function. 

We found the most common reason that the FEV1

 and FVC 

curves from Clinic B did not meet acceptability criteria was 

unsatisfactory exhalation, specifically lack of plateau, which 

could be readily improved through technician training and 

ongoing quality feedback from a supervising pulmonologist 

or audits by an independent third party. Following the 

release of the interim report, we reviewed a series of 

spirometry tests conducted by Clinic B’s technician and 

provided feedback for further improvement. Additional 

feedback and, if warranted and desired by the technician, 

training, could be provided by NIOSH as part of a future 

collaboration with the company. 

4.	 Longitudinal spirometry – Currently Clinic B only assesses 

the spirometry abnormality classifications (i.e., restrictive, 

obstructive, or mixed pattern). Given that spirometry is 

conducted serially and at least annually, we recommend 

longitudinal assessment of the lung function measurement 

using rate of decline over time (i.e., excessive decline in 

FEV1

) for early identification of at-risk workers. [Hnizdo 

et al. 2010]. Spirometry Longitudinal Data Analysis 

(SPIROLA) software is an easy-to-use visual and quantitative 

tool intended to assist the healthcare provider in monitoring 

and interpreting computerized longitudinal spirometry data 

for individuals as well as for a group. SPIROLA software can 

be downloaded for free from the NIOSH website and easily 

installed (http://www.cdc.gov/niosh/topics/spirometry/ 

spirola.html). 

5.	 Reference equations – The reference equations for 

spirometry, lung volume testing, and diffusing capacity 

testing currently used by Clinic B’s pulmonary function 

laboratory are outdated. We recommend reference 

equations derived from NHANES III [Hankinson et al. 

Page 54	 Health Hazard Evaluation Report 2009-0214-3153 
ReCommendAtions 

(Continued) 1999] for spirometry and from a sample of the general 

population of an entire state [Miller et al. 1983] for total 

lung capacity and diffusing capacity measurements. The 

staff at Clinic B’s pulmonary function laboratory indicated 

that they were in the process of obtaining new test 

equipment, which may address this issue. 

6.	 Radiograph quality – Radiograph quality improvement 

is crucial in reducing misclassification (over or underestimation) of lung abnormalities. We found the most 

common reasons that digital radiographs from Clinic B 

did not meet Grade 1 criteria for quality were the presence 

of artifact and exposure problems, which could be readily 

addressed through ongoing quality control. [NIOSH 2008]. 

(We provided Clinic B with information on improving 

quality of digital radiographs [see Appendix B]). 

7.	 ILO classification and awareness among consulting 

radiologists – We recommend classification of chest 

radiographs according to the ILO International 

Classification of Radiographs of Pneumoconioses [ILO 

2002]. This classification system allows physicians to 

describe the degree of dust-related changes present on a 

chest radiograph and to assess the radiograph quality. ILO 

standards are now available for digital radiographs (available 

at: http://www.ilo.org/safework/info/publications/ 

WCMS_168260/lang--en/index.htm). We also recommend 

increasing the awareness of the concern for interstitial lung 

diseases among radiologists who assess the surveillance 

chest radiographs by inserting a comment such as “Rule out 

indium lung disease/interstitial lung disease/pulmonary 

alveolar proteinosis” on the request form for the chest 

radiograph. By being aware of the motivation for these 

medical surveillance radiographs, hospital-based radiologists 

will be less likely to miss subtle abnormalities. 

8.	 Referral to pulmonologist – Until more is known about 

indium-related lung disease, the company should have a 

low threshold for referring workers to a pulmonologist for 

additional evaluation. Abnormalities on lung function 

testing that could indicate early indium-related lung 

disease (excessive decline in FEV1

, restrictive pattern or 

obstruction on spirometry, low total lung capacity, and/ 

or low diffusing capacity) should prompt evaluation by a 

pulmonologist. Such an evaluation would be expected 

to include repeat testing to confirm the abnormality, 

Health Hazard Evaluation Report 2009-0214-3153	 Page 55 
ReCommendAtions 

(Continued) more frequent surveillance (such as every six months) for 

confirmed abnormalities, and possibly additional diagnostic 

tests (such as HRCT, more sophisticated lung function tests, 

and/or bronchoscopy). As noted in the Discussion section 

of this report, the benefits of frequent, repeated HRCT 

are probably not warranted by natural history and must be 

weighed against radiation exposure and cost. 

9.	 Worker reassignment –ITO industry workers with suspected 

lung disease related to indium compounds should be 

reassigned to other jobs with minimal exposure. If such 

reassignment is not possible, then the worker should be 

provided a PAPR (with assigned protection factor of 1000) 

and instructed to use that respirator at all times throughout 

the facility. 

Company’s Update 

In November 2011, the company provided an update to NIOSH on 

new workplace changes since the September 2010 interim report. 

Below is a summary of the company’s most recent changes. 

Engineering Controls 

The company is focusing its efforts on those areas with the 

highest measured levels of dust utilizing a three-pronged approach 

comprised of these elements: eliminate, segregate, and remediate. 

They have installed upgraded reclaim milling and mixing 

equipment. They have segregated the planar grinding process into 

a separate work space as well as segregating rotary segment cutting. 

They have purchased two additional enclosed rotary grinding 

units, an enclosed planar finishing unit, and are in the process of 

procuring an enclosed planar grinding machine. 

Work Practices 

The company has developed a comprehensive training program 

that includes personal protective equipment protocols. They 

have also instituted an Operator Lead Safety Committee that is 

responsible for holding monthly meetings and teams of three 

employees audit all plant areas monthly to assess the environmental 

health and safety status. Area Supervisors are now responsible 

for random reviews of safety protocols within their area. A newly 

hired facility-dedicated EHS manager is responsible for reinforcing 

Page 56	 Health Hazard Evaluation Report 2009-0214-3153 
ReCommendAtions 

(Continued) the Respiratory Protection Program, conducting Safety reviews, 

and mentoring the Safety Committee. In addition, the company 

has instituted regularly scheduled environmental health and safety 

updates for all employees. 

Industrial Hygiene Testing 

The company has verified internal testing results with independent 

test results obtained from an outside consultant. In 2011, sampling 

equipment was purchased by the company which will allow 

for measuring exposure levels throughout the plant including 

stationary and personal sampling. A full-time facility-dedicated 

EHS manager was hired in February 2011 and has assumed 

responsibility for developing a comprehensive testing plan to 

sample all tasks and jobs a minimum of twice per year. 

Medical Surveillance 

The company’s medical surveillance program includes a physical 

examination, blood indium level, spirometry, static lung volumes, 

and diffusing capacity at hire. All production workers and 

managers spending time in production areas have blood indium 

level, spirometry, static lung volumes, and diffusing capacity testing 

annually. Beginning in 2012, surveillance for all production 

workers and those frequently exposed, including laboratory 

workers, will be increased to every six months. In addition to 

screening of all production employees, mandatory yearly screening 

of all non-production employees will also begin in January 2012. 

Health Hazard Evaluation Report 2009-0214-3153 Page 57 
 

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Page 62 Health Hazard Evaluation Report 2009-0214-3153 
tABles 

Table 1. Air sampling conducted by the company or its consultants from 2004 to 2010. 

Year Companyor 

Consultant 

Reporting 

Limit 

(mcg/sample) 

Analyte Sample 

Method 

Analytical 

Method 

2004 Consultant A 4.0 Indium Cassette Modified NIOSH 

7300 

± 50 Total Dust Cassette NIOSH 0500 

2005-2007 Company 0.05 Indium IOM OSHA 121/125G 

1.0 Tin Oxide IOM OSHA 121/125G 

100 Inhalable Dust IOM NIOSH 0500 

100 Respirable Dust IOM NIOSH 0600 

1.0 Indium Cassette OSHA 121/125G 

1.0 Tin/Tin Oxide Cassette OSHA 121/125G 

100 Total Dust Cassette NIOSH 0500 

1.0 Indium Surface 

Wipe OSHA 121/125G 

10 

(Stages 3, 4, Final, 

Total Respirable 

Dust) 

Anderson 

4-stage 

Impactor 

State of California 

Method 501 

10 (Stages 1, 2) 

Anderson 

4-stage 

Impactor 

Gravimetric 

analyss 

2007-2009 1.0 Indium Cassette Modified OSHA 

125G 

1.0 Tin Cassette Modified OSHA 

125G 

100 Total Dust Cassette Modified NIOSH 

0500 

2008 Consultant B 0.50 Indium Cassette WM001.4.0 inhouse 

5.0 Tin Cassette WM001.4.0 inhouse 

45 Total Weight Cassette WM001.01 inhouse 

2010 Consultant C Indium Cassette NIOSH 7300/ 

OSHA 125G 

Tin Cassette NIOSH 7300/ 

OSHA 125G 

Total Dust Cassette NIOSH 0500 

Health Hazard Evaluation Report 2009-0214-3153 Page 63 
tABles (Continued) 

Table 2. Criteria for spirometry grading. 

Grade FVC FEV1 

A 

1) ≥ 3 acceptable curves* and 

2) Best FVC not from last maneuver, or within 

50 mL of second best FVC, and 

3) FVC repeatable within 100 mL 

1) ≥ 3 acceptable curves* and 

2) Best FEV1

 not from last maneuver, or within 

50 mL of second best FEV1, and 

3) FEV1 repeatable within 100 mL 

B 1) ≥ 2 acceptable curves* and 

2) FVC repeatable within 150 mL 

1) ≥ 2 acceptable curves* and 

2) FEV1

 repeatable within 150 mL 

C 1) ≥ 2 acceptable curves* and 

2) FVC repeatable within 250 mL 

1) ≥ 2 acceptable curves* and 

2) FEV1

 repeatable within 250 mL 

D Only one acceptable curve* Only one acceptable curve* 

F No acceptable curves* No acceptable curves* 

*Acceptable curves are those that are free from artifacts, have good starts, and show satisfactory exhalation as per ATS/ERS 

criteria [Miller et al. 2005]. 

Table 3. Criteria for excessive decline in FEV1. 

Test interval Lower limit of normal* 

< 1.5 years 10.4 

1.5 - < 2.5 years 6.1 

2.5 - < 3.5 years 4.6 

3.5 - < 4.5 years 3.8 

≥ 4.5 years 3.2 

*Percent change per year [Wang, 2006]. 

Table 4. Range of surface wipe sampling for indium in 2005 and 2007. 

Surface wipe (N=19) 

Work Area n Indium (mcg/cm2) 

Administrative 3 3.4 – 4.7 

Employee car seats 5 1.5 - 13.7 

Men’s locker room 2 80 - 101 

Lunch room 4 3.0 - 31 

ITO sanding - inside respirator mask 1 4 

Reclaim - inside respirator mask 1 9.4 

Roof - exhaust outlets 3 15 - 109 

Page 64 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 5. Total and respirable dust, indium, and tin air concentrations measured in four general areas on 

April 8, 2010. 

Total (mg/m3) Respirable (mg/m3)
 

Dust Indium Tin Dust Indium Tin
 

Refinery
	

ITO
	

Grinding
	

Reclaim 

0.068* 0.018 0.001* ND† 0.002 0.001† 

0.049* 0.009 0.003 0.058* 0.003 0.002 

0.091* 0.016 0.001* ND† 0.002 ND† 

0.272 0.136 0.001* 0.135* 0.042 ND† 

* < MQC 

†ND indicates < MDC 

Table 6. Bulk samples collected on April 8, 2010 during the facility visit. 

Sample Description Department/process Mass (g) 

Indium Hydroxide 

Indium Oxide 

Tin Oxide 

Indium Tin Oxide 

(ITO) 

Unsintered ITO 

Sintered ITO 

Sintered ITO 

Sintered and 

Unsintered ITO 

Ventilation Dust 

Dross of dross 

Sludge 

White powder 

Yellow powder 

White powder 

Yellow liquid-particle 

suspension (slip) 

Yellow powder 

Black sintered tiles 

(small pieces) 

Grey sludge 

Coarse powder 

Black powder 

Dark grey coarse particulate 

material 

Solids in liquid 

Refinery/filter press 

Refinery 

ITO 

ITO/casting 

ITO/sanding room dust 

collector 

ITO/final inspection room 

Grinding/centrifuge 

Reclaim/blender 

Reclaim/furnace dust 

collector #13 

Reclaim 

Refinery/wastewater floor 

drain 

20.03 

15.13 

12.41 

71.02 

54.71 

39.01 

30.69 

76.28 

19.81 

34.04 

71.60 

Health Hazard Evaluation Report 2009-0214-3153 Page 65 
tABles (Continued) 

Table 7. Characteristics of workers participating in the medical surveillance program. 

Employment Status as of 

March 18, 2010 

Current Former All 

(N=30) (N=27) (N=57)

n (%) n (%) n (%) 

Age at hire (years) 

< 40 15 (50) 18 (67) 33 (58) 

> 40 15 (50) 9 (33) 24 (42) 

Smoking status*

 Ever 22 (73) 13 (48) 35 (61)

 Never 5 (17) 1 (4) 6 (11)

 Unknown 3 (10) 13 (48) 16 (28) 

Body mass index (BMI)†

 Under/normal weight 5 (17) 4 (15) 9 (16)

 Overweight 15 (52) 17 (65) 32 (58)

 Obese 9 (31) 5 (19) 14 (26) 

Tenure (years)‡ 

< 4 19 (63) 22 (81) 41 (72) 

> 4 11 (37) 5 (19) 16 (28) 

Surveillance time (months)§

 Mean (range) 38 (0-93) 13 (0-66) 26 (0-93) 

Job title category 

Production 22 (73) 20 (74) 42 (74)

 ITO grinder 3 (10) 5 (19) 8 (14)

 ITO operator 13 (43) 9 (33) 22 (39)

 Reclaim operator 3 (10) 4 (15) 7 (12)

 Refinery operator 3 (10) 2 (7) 5 (9) 

Other 8 (27) 7 (26) 15 (26)

 Other with some exposure 5 (17) 4 (15) 9 (16)

 Other with minimal exposure 3 (10) 3 (11) 6 (11) 

*Determined from spirometry reports. “Ever” includes current and former smokers. “Unknown” refers to workers for 

whom no smoking information was available. 

†Determined from the most recent spirometry reports. BMI ≤ 24.9 kg/m2

 = under/normal weight; 25 – 29.9 kg/m2 = 

overweight; ≥ 30 kg/m2 = obese. 

‡Defined as time between hire and 3/18/2010 for current workers and time between hire and termination for former 

workers. 

§Defined as time between first medical surveillance test of any kind and most recent medical surveillance test of any kind. 

Workers with only one testing interval were assigned a surveillance time of 0 months. 

Page 66 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 8. Proportions of workers with blood indium level of 5 mcg/L or greater at any time after hire and 

distributions of the average blood indium level, by work status, hire year, and job category. 

Characteristics	 Blood indium level Overall Median† for 

≥5 mcg/L median* subset with blood 

n (%) (range) indium level ≥5 

mcg/L (range) 

N=42		 N=42 N=21 

All	 21 (50) 3.8 (2.5-63) 12 (5.1-63) 

Employment Status

 Current 11 (50) 3.8 (2.5-56) 12 (5.1-56) 

Former 10 (50) 3.8 (2.5-63) 12 (5.1-63) 

Hire year

 < 2007 19 (70) 11.0 (2.5-63) 13 (5.1-63) 

≥ 2007 2 (13) 2.5 (2.5-6.2) 5.7 (5.1-6.2) 

Job title category 

ITO grinder 4 (57) 5.1 (2.5-56) 24 (5.1-56) 

ITO operator 11 (65) 9 (2.5-27) 12 (5.1-27) 

Reclaim operator 3 (60) 5.1 (2.5-54) 49 (5.1-54) 

Refinery operator 3 (75) 10 (2.5-63) 14 (6.2-63) 

Other with some exposure 0 (0) 2.5 (all 2.5) N/A

Other with minimal 

exposure 0 (0)	 2.5 (all 2.5) N/A

*Using each worker’s most recent after-hire test. Tests with the reported result “none detected” or “0 mcg/L” were assigned a 

concentration of 2.5 mcg/L, half the reporting value of 5 mcg/L. 

†Using each worker’s most recent after-hire test. Tests with the reported result “none detected” or “0 mcg/L” were excluded 

from the analysis. 

Health Hazard Evaluation Report 2009-0214-3153 Page 67
tABles (Continued) 

Table 9a. Quality grades for FVC and FEV1 from 138 spirometry tests on 55 workers. 

FEV1 

A B C D F Total 

# (%) 

FVC 

A 12 5 0 0 0 17 (12) 

B 2 26 6 1 0 35 (25) 

C 0 3 0 0 0 3 (2) 

D 0 1 1 21 0 23 (17) 

F 0 0 0 0 60 60 (44) 

Total 

# (%) 14 (10) 35 (25) 7 (5) 22 (16) 60 (44) 138 

Table 9b. Quality grades for FVC and FEV1 from spirometry tests by Clinic A. 

FEV1 

A B C D F Total 

# (%) 

FVC 

A 9 3 0 0 0 12 (25) 

B 2 15 4 0 0 21 (45) 

C 0 2 0 0 0 2 (4) 

D 0 1 1 5 0 7 (15) 

F 0 0 0 0 5 5 (11) 

Total 

# (%) 11 (23) 21 (45) 5 (11) 5 (11) 5 (11) 47 

Table 9c. Quality grades for FVC and FEV1 from spirometry tests by Clinic B. 

FEV1 

A B C D F Total 

# (%) 

FVC 

A 3 2 0 0 0 5 (6) 

B 0 11 2 1 0 14 (15) 

C 0 1 0 0 0 1 (1) 

D 0 0 0 16 0 16 (18) 

F 0 0 0 0 55 55 (60) 

Total 

# (%) 3 (3) 14 (15) 2 (2) 17 (19) 55 (60) 91 

Page 68 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 10. Quality grades for FVC and FEV1 from the most recent 

spirometry tests of 45 workers tested after hire. 

FEV1 

A B C D F Total 

# (%) 

FVC 

A 5 2 0 0 0 7 (16) 

B 0 6 2 0 0 8 (18) 

C 0 1 0 0 0 1 (2) 

D 0 0 0 7 0 7 (16) 

F 0 0 0 0 22 22 (49) 

Total 

# (%) 5 (11) 9 (20) 2 (4) 7 (16) 22 (49) 45 

Table 11. Ever had a restrictive pattern on spirometry after hire, 

by worker characteristics. 

n (%) 

All (N=45) 18 (40) 

Employment Status

 Current (N=27) 9 (33)

 Former (N=18) 9 (50) 

Hire year

 < 2007 (N=25) 13 (52)

 ≥ 2007 (N=20) 5 (25) 

Job title category 

ITO grinder (N=8) 2 (25) 

ITO operator (N=17) 8 (47) 

Reclaim operator (N=5) 2 (40) 

Refinery operator (N=4) 1 (25) 

Other with some exposure (N=7) 4 (57) 

Other with minimal exposure (N=4) 1 (25) 

Blood indium (available in N=39) 

> 5 mcg/L (N=20) 9 (45)

 < 5 mcg/L (N=19) 6 (32) 

Health Hazard Evaluation Report 2009-0214-3153 Page 69
tABles (Continued) 

Table 12. Comparison of restrictive pattern on the most recent after-hire 

spirometry test to U.S. adult population (NHANES III) data.* 

N Observed 

number 

Expected 

number 

Prevalence 

ratio (95% CI)† 

Overall 

Employment status 

Current workers 

Former workers 

Hire year 

< 2007 

> 2007 

Job title category 

ITO operator 

ITO grinder 

Other – some exposure 

43 

25 

18 

24 

19 

15 

8 

7 

14 

7 

7 

9 

5 

5 

2 

4 

3.5

2.2

1.3

1.7

1.8

1.1

0.6 

0.8 

4.0 (2.4-6.7) 

3.2 (1.5-6.5) 

 5.4 (2.6-11.0) 

5.3 (2.8-10.1) 

2.8 (1.2-6.4) 

4.6 (2.0-10.7) 

3.3 (0.9-12.0) 

5.2 (2.0-13.5) 

*NHANES comparison was done in 43 workers. Two workers were 

Asian and not included in the analysis because expected values for 

this race were not available. Includes all quality tests. 

†Reflects ratio of observed prevalence to expected prevalence and 

was determined using indirect standardization for race, sex, age, 

cigarette smoking status, and body mass index. Workers for whom 

smoking status was unavailable were assumed to be smokers. 

CI=confidence interval. 

Table 13. Comparison of at-hire and most recent spirometry interpretations for 18 workers 

tested at hire and during employment.* 

Most recent interpretation 

NORMAL OBSTRUCTION RESTRICTIVE 

At-hire interpretation 

NORMAL 9 1† 3‡ 

OBSTRUCTION 0 1 0 

RESTRICTIVE 1 0 3 

*None of the 18 workers included in this analysis had a mixed pattern. 

†One had excessive decline in FEV1 

‡Three had excessive decline in FEV1 

Page 70 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 14a. Ever had an excessive decline in FEV1 after hire, 

by worker characteristics.* 

n (%) 

Total (N=41) 12 (29) 

Employment Status

 Current (N=27) 8 (30)

 Former (N=14) 4 (29) 

Hire year

 < 2007 (N=22) 8 (36)

 ≥ 2007 (N=19) 4 (21) 

Job title category 

ITO Grinder (N=7) 4 (57) 

ITO Operator (N=15) 5 (33) 

Reclaim Operator (N=5) 1 (20) 

Refinery Operator (N=4) 0 (0) 

Other with some exposure (N=7) 1 (14) 

Other with minimal exposure (N=3) 1 (33) 

Blood indium (available in N=35) 

> 5 mcg/L (N=19) 7 (37)

 < 5 mcg/L (N=16) 3 (19) 

*Five workers with spirometry interpretation of obstruction were included in these analyses. 

Health Hazard Evaluation Report 2009-0214-3153 Page 71
tABles (Continued) 

Table 14b. Ever had an excessive decline in FEV1 after hire, 

by worker characteristics.* 

n (%) 

Total (N=36) 8 (22) 

Employment Status

 Current (N=22) 4 (18)

 Former (N=14) 4 (29) 

Hire year

 < 2007 (N=19) 5 (26)

 ≥ 2007 (N=17) 3 (18) 

Job title category 

ITO grinder (N=5) 2 (40) 

ITO operator (N=12) 3 (25) 

Reclaim operator (N=5) 1 (20) 

Refinery operator (N=4) 0 (0) 

Other with some exposure (N=7) 1 (14) 

Other with minimal exposure (N=3) 1 (33) 

Blood indium (available in N=31) 

> 5 mcg/L (N=16) 4 (25)

 < 5 mcg/L (N=15) 3 (20) 

*Five workers with spirometry interpretation of obstruction were excluded from these analyses. 

Page 72 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 15. Ever had low total lung capacity (TLC) after hire, by worker characteristics. 

n (%) 

Total (N=35) 8 (23) 

Employment Status 

Current (N=27) 7 (26) 

Former (N=8) 1 (13) 

Hire year 

< 2007 (N=15) 5 (33) 

≥ 2007 (N=20) 3 (13) 

Job title category 

ITO grinder (N=6) 0 (0) 

ITO operator (N=12) 3 (25) 

Reclaim operator (N=5) 2 (40) 

Refinery operator (N=3) 0 (0) 

Other with some exposure (N=6) 3 (50) 

Other with minimal exposure (N=3) 0 (0) 

Blood indium (available in N=29) 

> 5 mcg/L (N=14) 4 (29)

 < 5 mcg/L (N=15) 2 (13) 

Health Hazard Evaluation Report 2009-0214-3153 Page 73
tABles (Continued) 

Table 16. Ever had low diffusing capacity (DLCO) after hire, 

by worker characteristics. 

n (%) 

Total (N=35) 8 (23) 

Employment Status 

Current (N=27) 5 (19) 

Former (N=8) 3 (38) 

Hire year 

< 2007 (N=15) 4 (27) 

≥ 2007 (N=20) 4 (25) 

Job title category 

ITO grinder (N=6) 2 (33) 

ITO operator (N=12) 4 (33) 

Reclaim operator (N=5) 1 (20) 

Refinery operator (N=3) 0 (0) 

Other with some exposure (N=6) 1 (17) 

Other with minimal exposure (N=3) 0 (0) 

Blood indium (available in N=29) 

> 5 mcg/L (N=14) 4 (29)

 < 5 mcg/L (N=15) 4 (27) 

Page 74 Health Hazard Evaluation Report 2009-0214-3153 
tABles (Continued) 

Table 17a. Agreement between restrictive pattern on spirometry and excessive decline in FEV1.* 

Restrictive pattern Total 

No Yes 

Excessive decline No 20 9 29 

Yes 5 7 12 

Total 25 16 41 

*Five workers with spirometry interpretation of obstruction were included in these analyses. 

Table 17b. Agreement between restrictive pattern on spirometry and excessive decline in FEV1.* 

Restrictive pattern Total 

No Yes 

Excessive decline No 19 9 28 

Yes 1 7 8 

Total 20 16 36 

*Five workers with spirometry interpretation of obstruction were excluded from these analyses. 

Table 17c. Agreement between restrictive pattern on spirometry and low total lung capacity (TLC). 

Restrictive pattern Total 

No Yes 

TLC Normal 22 5 27 

Low 1 7 8 

Total 23 12 35 

Table 17d. Agreement between restrictive pattern on spirometry and low diffusing capacity (DLCO). 

Restrictive pattern Total 

No Yes 

DLCO Normal 18 9 27 

Low 5 3 8 

Total 23 12 35 

Table 17e. Agreement between low total lung capacity (TLC) and low diffusing capacity (DLCO). 

TLC Total 

Normal Low 

DLCO Normal 21 6 27 

Low 6 2 8 

Total 27 8 35 

Health Hazard Evaluation Report 2009-0214-3153 Page 75 
tABles (Continued) 

Table 18. Summary of exposure estimates and adverse health outcomes ever after hire by job title category. 

ITO Grinder ITO Operator Reclaim 

Operator 

Refinery 

Operator 

Other 

jobs some 

exposure 

Other jobs 

minimal 

exposure 

Indium 

exposure (mg/ 

m3

)* 

0.17 

(0.1 - 0.5) 

n = 8 

0.13 

(0.03 - 0.6) 

n = 15 

0.7 

(0.06 - 4.0) 

n = 10 

1.5 

(0.5 - 3.6) 

n = 5 

N/A N/A 

Blood indium 

level ≥ 5 

mcg/L 

57% (4/7) 65% (11/17) 60% (3/5) 75% (3/4) 0 (0/5) 0 (0/4) 

Restrictive 

pattern on 

spirometry 

25% (2/8) 47% (8/17) 40% (2/5) 25% (1/4) 57% (4/7) 25% (1/4) 

Excessive 

decline FEV1 

57% (4/7) 33% (5/15) 20% (1/5) 0 (0/4) 14% (1/7) 33% (1/3) 

Restriction 

(low total lung 

capacity) 

0 (0/6) 25% (3/12) 40% (2/5) 0 (0/3) 50% (3/6) 0 (0/3) 

Low diffusing 

capacity 33% (2/6) 33% (4/12) 20% (1/5) 0 (0/3) 17% (1/6) 0 (0/3) 

Abnormal 

CXR† 0 (0/3) 0% (0/13) 67% (2/3) 0 (0/3) 0 (0/5) 0 (0/1) 

Case of 

pulmonary 

alveolar 

proteinosis 

0 (0/8) 5% (1/22) 0 (0/7) ‡ 0 (0/5) 0 (0/9) 0 (0/5) 

*GM (range) for full- or partial-shift historical personal samples analyzed for total indium 

†In addition, two former workers (one reclaim operator, one ITO operator) had diffuse abnormalities on chest radiographs 

done after hire outside of the formal surveillance program. 

‡One case occurred in a Reclaim Operator prior to the company’s purchase of the facility. 

Page 76 Health Hazard Evaluation Report 2009-0214-3153 
figuRes
 

Figure 1. Production of indium-tin oxide targets and reclamation of indium metal. 

Loaded buckets of IndiumOxide froma sieve: 6:53 1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

Loaded furnace: 7:00 Ͳ 8:23*

06:50:4407:05:4407:20:4407:35:4407:50:4408:05:4408:20:4408:35:4408:50:4409:05:4409:20:4409:35:4409:50:4410:05:4410:20:4410:35:4410:50:4411:05:4411:20:4411:35:4411:50:4412:05:4412:20:4412:35:4412:50:4413:05:4413:20:4413:35:4413:50:4414:05:4414:20:4414:35:4414:50:4415:05:4415:20:44

Figure 2. Real-time air dust concentrations in the refinery area on April 8, 2010. The average 

concentration over 513 minutes sampling period was 0.07 mg/m3

. *The task was completed sometime 

between 7:00 and 8:23. 

Health Hazard Evaluation Report 2009-0214-3153 Page 77
( ) 

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

07:05:04 06:57:1907:20:04 07:12:1907:35:0407:50:0408:05:04

07:27:1907:42:1907:57:19

08:20:04 08:12:1908:35:04 08:27:1908:50:04 08:42:1909:05:04 08:57:1909:20:04 09:12:1909:35:04 09:27:1909:50:04 09:42:1910:05:04 09:57:1910:20:04 10:12:1910:35:04 10:27:1910:50:04 10:42:1911:05:04 10:57:1911:20:04 11:12:1911:35:04

11:27:19

11:50:04

11:42:1911:57:19

12:05:04 12:12:1912:20:04 12:27:1912:35:04 12:42:1912:50:04 12:57:1913:05:04 13:12:1913:20:04 13:27:1913:35:04 13:42:1913:50:04 13:57:1914:05:04 14:12:1914:20:04 14:27:1914:35:04 14:42:1914:50:0415:05:04

14:57:1915:12:19

figuRes Continued

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Figure 3. Real-time air dust concentrations in the ITO department on April 8, 2010. The average 

concentration over 509 minutes sampling period was 0.031 mg/m3

. 

1

Enclosed grindersran forthe entire shift

Ran partially enclosed grinder: 11:00Ͳ11:20

Figure 4. Real-time air dust concentrations in the grinding area on April 8, 2010. The average 

concentration over 496 minutes sampling period was 0.068 mg/m3

. 

Page 78 Health Hazard Evaluation Report 2009-0214-3153 
figuRes (Continued) 

Figure 5. Real-time air dust concentrations in the reclaim area on April 8, 2010. The average 

concentration over 478 minutes sampling period was 0.168 mg/m3

. Four peaks of approximately 0.25 

mg/m3

 were observed between 8:50 and 13:14 (no task identification due to the lack of observation). 

Figure 6. Mean and range of after-hire blood indium level by year. Tests with the reported result “none 

detected” were assigned a concentration of 2.5 mcg/L, half the reporting value of 5 mcg/L. 

Health Hazard Evaluation Report 2009-0214-3153 Page 79 
figuRes (Continued) 

Figure 7. Blood indium level over time for 21 workers with blood indium concentration of 5 mcg/L or 

greater at any time after hire. Tests done at hire are included, if available. 

Page 80 Health Hazard Evaluation Report 2009-0214-3153 
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA 

A.1. Number of samples 

Number of Personal Air Samples by Sample Type 

Number of Personal Partial- to Full-Shift / Short Duration 

by Sample Type 

Cassette IOM Cyclone 

Total Dust 37/25 --­ 2/0 

Total Indium 38/25 --­ 4/1 

Total Tin 30/12 --­ ---

Inhalable Dust --- * 9/4 ---

Inhalable Indium --­ 2/1 ---

Inhalable Tin --­ 0/0 --­

Respirable Dust --­ 9/4 --­

Respirable Indium --­ 9/4 --­

Respirable Tin --­ 8/3 --­

* Sample not collected 

Number of General Area Air Samples by Sample Type 

Number of Area Partial- to Full-Shift / Short Duration 

by Sample Type 

Cassette IOM 

Total Dust 21/4 --­

Total Indium 21/4 --­

Total Tin 9/1 ---

Inhalable Dust ---* 0/1 

Inhalable Indium --­ ---

Inhalable Tin --­ --­

Respirable Dust --­ 0/1 

Respirable Indium --­ 0/1 

Respirable Tin --­ 0/0 

* Sample not collected 

Health Hazard Evaluation Report 2009-0214-3153 Page 81 
 

Page 82 Health Hazard Evaluation Report 2009-0214-3153 Number of Personal IOM Samples by Work Area Work Area Dust Inhalable Partial- to Full-Shift Dust Inhalable Short Duration Dust Respirable Partial- to Full-Shift Dust Respirable Short Duration Indium Inhalable Partial- to Full-Shift Indium Inhalable Short Duration Indium Respirable Partial- to Full-Shift Indium Respirable Short Duration Tin Inhalable Partial- to Full-Shift Tin Inhalable Short Duration Tin Respirable Partial- to Full-Shift Tin Respirable Short Duration ITO Department 3 ---* 3 --­ --­ 1 3 2 --­ --­ 3 --­ Grinding 4 2 4 2 1 --­ 4 --­ --­ --­ 3 1 Reclaim 2 --­ 2 --­ 1 --­ 2 --­ --­ --­ 2 --­ Refinery --­ 2 --­ 2 --­ --­ --­ 2 --­ --­ --­ 2 Total 9 4 9 4 2 1 9 4 --- --- 8 3 Sample not collected *Number of Personal Cassettes by Work Area for Indium (In) and Tin (Sn) by Year – Partial- to Full-Shift Duration Work Area 2004 In 2004 Sn 2005 In 2005 Sn 2006 In 2006 Sn 2007 In 2007 Sn 2008 In 2008 Sn 2009 In 2009 Sn 2010 In 2010 Sn Total In Total Sn ITO Dept ---* --­ --­ --­ 1 1 5 2 5 5 3 3 1 1 15 12 Grinding --­ --­ --­ --­ --­ --­ 3 2 1 1 4 4 --­ --­ 8 7 Reclaim --­ --­ --­ --­ --­ --­ 3 1 3 3 2 2 2 2 10 8 Refinery --­ --­ --­ --­ --­ --­ 3 1 1 1 1 1 --­ --­ 5 3 Total 1 1 14 6 10 10 10 10 3 3 38 30 

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Sample not collected * 
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Number of Personal Cassettes by Work Area for Indium (In) and Tin (Sn) by Year – Short Duration Work Area 2004 In 2004 Sn 2005 In 2005 Sn 2006 In 2006 Sn 2007 In 2007 Sn 2008 In 2008 Sn 2009 In 2009 Sn 2010 In 2010 Sn Total In Total Sn ITO Dept ---* --- --- --- --- --- 3 3 --- --- --- --- --- --- 3 3 Grinding --- --- --- --- 1 1 2 2 --- --- --- --- --- --- 3 3 Reclaim --- --- --- --- --- --- --- --- 1 1 --- --- --- --- 1 1 Refinery 9 --- --- --- 2 2 6 2 1 1 --- --- --- --- 18 5 Total 9 --- --- --- 3 3 11 7 2 2 --- --- --- --- 25 12 Sample not collected * 

Health Hazard Evaluation Report 2009-0214-3153 Page 83 
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued)

 Concentrations A.2.

 Concentrations (in mg/m A.2.1 3 ) by Work Area by Sample Duration in Personal Air Cassette Samples

Personal Cassette Indium (N=63)

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean 

Partial- to

Full-Shift

Geometric

Mean 

n 

Short Duration

Range 

Short Duration

Mean 

Short Duration

Geometric

Mean 

ITO department 15 0.03 – 0.59 0.18 0.13 3 0.07 – 0.45 0.31 0.23 

Grinding 8 0.07 – 0.45 0.19 0.17 3 0.17 – 0.26 0.23 0.22 

Reclaim 10 0.06 – 4.0 1.3 0.74 1 0.10 0.10 Refinery 5 0.47 – 3.6 1.8 1.5 18 0.03 – 46 6.6 1.9 

Total 38 25

Personal Cassette Tin (N=42) 

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean 

Partial- to

Full-Shift

Geometric

Mean 

n 

Short Duration

Range 

Short Duration

Mean 

Short Duration

Geometric

Mean 

ITO department 12 0.0005 – 0.03 0.006 0.003 3 0.0015 – 0.002 0.002 0.002 

Grinding 7 0.005 – 0.02 0.01 0.01 3 0.01 – 0.03 0.02 0.02 

Reclaim 8 0.002 – 0.12 0.04 0.02 1 0.01 0.01 

Refinery 3 0.001 – 0.003 0.002 0.001 5 0.002 – 0.08 0.02 0.006 

Total 30 12 

Personal Cassette Total Dust (N=62) 

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean 

Partial- to

Full-Shift

Geometric

Mean 

n 

Short Duration

Range 

Short Duration

Mean 

Short Duration

Geometric

Mean 

ITO department 15 0.05 – 0.89 0.32 0.24 3 0.16 – 0.93 0.65 0.50 

Grinding 8 0.20 – 0.85 0.40 0.36 3 0.49 – 1.10 0.75 0.71 

Reclaim 10 0.22 – 5.2 2.0 1.2 1 0.13 0.13 

Refinery 4 0.68 – 6.4 3.0 2.1 18 0.35 – 65.0 10.0 3.2 

Total 37 25 

Page 84 Health Hazard Evaluation Report 2009-0214-3153 
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Personal Cyclone Indium (N=5) Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean Partial- to Full-Shift Geometric Mean n Short Duration Range Short Duration Mean Short Duration Geometric Mean Grinding 3 0.0004 – 0.11 0.04 0.01 --­ ITO Dept ---* 1 0.03 0.03 Reclaim 1 0.27 0.27 --­ Total 4 1 *Sample not collected Personal Cyclone Total Dust (N=2 ) n Partial- to Full- Shift Range Partial- to Full- Shift Mean Partial- to Full- Shift GM n Short Duration Range Short Duration Mean Short Duration GM Grinding 2 0.217 – 0.218 0.22 0.22 ---* Sample not collected * 

Health Hazard Evaluation Report 2009-0214-3153 Page 85
 

 Concentrations (in mg/m A.2.2. 3 ) by Work Area by Year in Personal Air Cassette Samples

Geometric Mean Indium Concentrations by Work Area by Year in Personal Cassette Samples – Partial- to Full-Shift Duration

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) 

Page 86 Health Hazard Evaluation Report 2009-0214-3153 Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* --­ 0.25 n=1 0.13 n=5 0.15 n=5 0.10 n=3 0.07 n=1 Grinding --­ --­ --­ 0.19 n=3 0.17 n=1 0.15 n=4 --­ Reclaim --­ --­ --­ 1.4 n=3 0.53 n=3 3.3 n=2 0.10 n=2 Refinery --­ --­ --­ 1.2 n=3 1.1 n=1 3.6 n=1 --­ * No sample collected Geometric Mean Indium Concentrations by Work Area by Year in Personal Cassette Samples – Short Duration Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* --­ --­ 0.23 n=3 --­ --­ --­ Grinding --­ --­ 0.16 n=1 0.26 n=2 --­ --­ --­ Reclaim --­ --­ --­ --­ 0.10 n=1 --­ --­ Refinery 3.3 n=9 --­ 3.4 n=2 0.9 n=6 0.5 n=1 --­ --­ * No sample collected 
 

Geometric Mean Total Dust Concentrations by Work Area by Year in Personal Cassette Samples – Partial- to Full-Shift Duration

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) 

Health Hazard Evaluation Report 2009-0214-3153 Page 87 Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* --­ 0.57 n=1 0.26 n=5 0.27 n=5 0.13 n=3 0.22 n=1 Grinding --­ --­ --­ 0.51 n=3 0.25 n=1 0.31 n=4 --­ Reclaim --­ --­ --­ 2.6 n=3 0.67 n=3 3.9 n=2 0.33 n=2 Refinery --­ --­ --­ 2.6 n=3 1.1 n=1 --­ --­ No sample collected *Geometric Mean Total Dust Concentrations by Work Area by Year in Personal Cassette Samples – Short Duration Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* --­ --­ 0.50 n=3 --­ --­ --­ Grinding --­ --­ 0.68 n=1 0.73 n=2 --­ --­ --­ Reclaim --­ --­ --­ --­ 0.13 n=1 --­ --­ Refinery 4.3 n=9 --­ 4.8 n=2 2.4 n=6 0.53 n=1 --­ --­ No sample collected * 
 

 Concentrations (in mg/m A.2.3. 3) by Work Area by Sample Duration in General Area Cassette Samples

Area Cassette Indium (N=25) 

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean 

Partial- to

Full-Shift

Geometric

Mean 

n 

Short Duration

Range 

Short Duration

Mean 

Short Duration

Geometric

Mean 

Grinding 13 0.002 – 0.45 0.08 0.03 3 0.01 – 0.07 0.04 0.03 

ITO Department 3 0.009 – 0.02 0.01 0.01 1 0.17 0.17 

Reclaim 5 0.02 – 4.5 1.4 0.45 ---* Total 21 4 

No sample collected * 

Area Cassette Tin (N=10) 

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean 

Partial- to

Full-Shift

Geometric

Mean 

n 

Short Duration

Range 

Short Duration

Mean 

Short Duration

Geometric

Mean 

Grinding 2 0.007 – 0.02 0.01 0.01 1 .01 .01 

ITO Department 3 0.0009 – 0.001 0.001 0.001 ---* 

Reclaim 4 0.001 – 0.37 0.11 0.02 --­

Total 9 1

No sample collected * 

Area Cassette Total Dust (N=25)

Work Area n Partial- to Full- Shift Range Partial- to Full- Shift Mean Partial- to Full- Shift GM n Partial- to Full- Shift Range Partial- to Full- Shift Mean Partial- to Full- Shift GM 

Grinding 13 0.05 – 0.85 0.27 0.20 3 0.25 – 1.0 0.61 0.52 

ITO Department 3 0.02 – 0.14 0.06 0.04 1 0.63 0.63 

Reclaim 5 0.16 – 6.6 2.3 1.2 ---* 

Total 21 4 

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) 

Page 88 Health Hazard Evaluation Report 2009-0214-3153 

No sample collected * 
 

 Concentrations (in mg/m A.2.4. 3 ) by department by year in general area cassette samples

Geometric Mean Indium Concentrations by Work Area by Year in General Area Cassette Samples – Partial- to Full-Shift Duration

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) 

Health Hazard Evaluation Report 2009-0214-3153 Page 89 Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* 0.01 n=3 --­ --­ --­ --­ --­ Grinding --­ 0.03 n=13 --­ --­ --­ --­ --­ Reclaim --­ 1.0 n=2 4.5 n=1 --­ --­ --­ 0.06 n=2 Refinery --­ --­ --­ --­ --­ --­ --­ No sample collected *Geometric Mean Indium Concentrations by Work Area by Year in General Area Cassette Samples – Short Duration Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* 0.17 n=1 --­ --­ --­ --­ --­ Grinding --­ 0.03 n=3 --­ --­ --­ --­ --­ Reclaim --­ --­ --­ --­ --­ --­ Refinery --­ --­ --­ --­ --­ --­ No sample collected *
 

Geometric Mean Total Dust Concentrations by Work Area by Year in General Area Cassette Samples – Partial- to Full-Shift Duration

Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) 

Page 90 Health Hazard Evaluation Report 2009-0214-3153 Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* .04 n=3 --­ --­ --­ --­ --­ Grinding --­ 0.20 n=13 --­ --­ --­ --­ --­ Reclaim --­ 2.1 n=2 6.6 n=1 --­ --­ --­ 0.28 n=2 Refinery --­ --­ --­ --­ --­ --­ --­ No sample collected *Geometric Mean Total Dust Concentrations by Work Area by Year in General Area Cassette Samples – Short Duration Work Area 2004 2005 2006 2007 2008 2009 2010 ITO Dept ---* .63 n=1 --­ --­ --­ --­ --­ Grinding --­ --­ 0.52 n=3 --­ --­ --­ --­ Reclaim --­ --­ --­ --­ --­ --­ --­ Refinery --­ --­ --­ --­ --­ --­ --­ No sample collected *
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Concentrations (in mg/m A.2.5. 3 ) by Work Area by Size and Duration in Personal IOM Samples Personal IOM Indium (N=11) Partial- to Full-Shift Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding 1 0.41 0.41 4 0.01 – 0.03 0.02 0.02 ITO Department ---* 3 0.03 –0.08 0.06 0.05 Reclaim 1 3.3 3.3 2 0.11 – 1.1 0.62 0.35 Total 2 9 No sample collected * Personal IOM Indium (N=5) Short Duration Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding ---* 2 0.01 – 0.04 0.02 0.02 ITO Department 1 0.62 0.62 --­ Reclaim --­ --­ Refinery --­ 2 0.21 – 0.47 0.34 0.31 Total 1 4 No sample collected * 

Health Hazard Evaluation Report 2009-0214-3153 Page 91
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Personal IOM Tin (N=8) Partial--- to Full---Shift Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding ---* 3 0.001 – 0.002 0.002 0.001 ITO Department --­ 3 0.001 – 0.004 0.002 0.001 Reclaim --­ 2 0.09 – 0.89 0.49 0.28 Total 0 8 No sample collected * Personal IOM Tin (N=3) Short Duration Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding ---* 1 0.002 0.002 Refinery --­ 2 0.003 – 0.005 0.004 0.004 Total 0 3 *No sample collected Personal IOM Total Dust (N=9) Partial- to Full-Shift Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding 4 0.05 – 1.1 0.44 0.26 4 0.05 – 0.21 0.15 0.13 ITO Department 3 0.37 – 1.6 0.79 0.63 3 0.18 – 0.27 0.21 0.21 Reclaim 2 3.8 – 14 8.7 7.2 2 0.56 – 2.1 1.3 1.1 Total 9 9 

Page 92 Health Hazard Evaluation Report 2009-0214-3153 
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Personal IOM Total Dust (N=4) Short Duration Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding 2 1.01 – 1.04 1.0 1.0 2 0.71 – 1.04 0.88 0.86 ITO Department ---* --­ Reclaim --­ --­ Refinery 2 7.1 – 8.9 8.0 8.0 2 2.0 – 2.1 2.0 2.0 Total 4 4 No sample collected * 

Health Hazard Evaluation Report 2009-0214-3153 Page 93
Appendix A: HistoRiCAl industRiAl Hygiene sAmpling dAtA (Continued) Concentrations (in mg/m A.2.6. 3 ) by Work Area by Size in Area IOM samples Area IOM Indium (N=1) Short Duration Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding ---* 1 0.03 0.03 *No sample collected Area IOM Total Dust (N=1) Short Duration Work Area Inhalable n Inhalable Range Inhalable Mean Inhalable Geometric Mean Respirable n Respirable Range Respirable Mean Respirable Geometric Mean Grinding 1 .0.25 0.25 1 0.25 0.25 

Page 94 Health Hazard Evaluation Report 2009-0214-3153 
 

 

 

Appendix B: letteR to CliniC B RegARding quAlity of 

CHest RAdiogRApHs 

DEPARTMENT OF HEALTH & HUMAN SERVICES Public Health Service

 ________________________________________________________________________________________________

 Phone: (304) 285-5751 Centers for Disease Control

 Fax: (304) 285-5820 and Prevention (CDC) 

National Institute for Occupational 

Safety and Health (NIOSH) 

1095 Willowdale Road 

Morgantown, WV 26505-2888 

April 16, 2010 

Physician 

Clinic B 

Dear Doctor, 

On behalf of the NIOSH team that visited the indium-tin oxide production facility in Rhode Island 

from April 7-9, 2010, we would like to thank you for taking the time to meet with us. As part of 

our Health Hazard Evaluation, we arranged for the digitally-acquired chest radiographs from your 

institution to be classified according to the ILO Classification System by two or more NIOSH B 

readers. 

The ILO Classification System includes an assessment of radiograph quality as follows: 

Grade 1: Good 

Free of technical imperfections or artifacts 

Grade 2: Acceptable 

No technical defects or artifacts likely to impair classification 

Grade 3: Acceptable 

With technical defects or artifacts but still adequate for classification 

Grade 4: U/R 

Unacceptable for classification 

If quality is not Grade 1, an indication of the technical defect(s) is made. Minor errors in positioning 

and handling artifacts that do not overlie the heart or lungs would usually be classified as Grade 2; 

minor degrees of over- or underexposure and minor departures from proper radiographic contrast 

would usually be classified as Grade 3; and gross over- or underexposure, gross unsharpness due to 

motion or poor contact, and gross departures from proper radiographic contrast as U/R. 

During our visit, we provided some feedback on the quality of the digitally-acquired radiographs 

from your institution. None of the radiographs we reviewed had Grade 1 quality and many had Grade 

3 quality. The B readers indicated that the radiographs had problems with mottle (which refers to 

grainy, blotchy, textured, or snowy appearance in a radiographic image) and exposure. Such quality 

issues can lead to misclassification of radiographs. Defects can be misinterpreted to represent disease 

Health Hazard Evaluation Report 2009-0214-3153 Page 95 
 

 

 

Appendix B: letteR to CliniC B RegARding quAlity of 

CHest RAdiogRApHs (Continued) 

when none exists, or true interstitial lung disease can be misinterpreted as radiographic artifact. 

Either form of misclassification would impact your efforts to conduct medical surveillance.
	

Enclosed you will find a list of the radiographs reviewed and the B reader’s classification, including 

quality grading. We hope this information and the CD we provided containing NIOSH Publication 

No. 2008-139 (Application of the ILO International Classification of Radiographs of Pneumoconioses 

to Digital Chest Radiographic Images, A NIOSH Scientific Workshop) are helpful to you and the 

radiology department. Please do not hesitate to contact us if additional questions arise. 

Sincerely, 

Kristin Cummings, MD, MPH 

Eva Suarthana, MD, PhD 

Field Studies Branch 

Division of Respiratory Disease Studies 

Page 96 Health Hazard Evaluation Report 2009-0214-3153 
ACknowledgements And 

AvAilABility of RepoRt 

The Respiratory Disease Hazard Evaluation and Technical 

Assistance Program of 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 (OSH) Act of 1970, 29 U.S.C. 

669(a)(6), or Section 501(a)(11) of the Federal Mine Safety and 

Health Act of 1977, 30 U.S.C. 951(a)(11), which authorizes the 

Secretary of Health and Human Services, following a written 

request from any employers 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. 

The Respiratory Disease Hazard Evaluation and Technical 

Assistance Program 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 Kristin Cummings, Eva Suarthana, 

Gregory A. Day, Marcia L. Stanton, Rena Saito, and Kathleen 

Kreiss, of the Field Studies Branch, Division of Respiratory Disease 

Studies. Analytical support was provided by Nicole Edwards and 

Xiaoming Liang. Statistical support was provided by Kathy Fedan. 

Desktop publishing was performed by Tia McClelland. 

Copies of this report have been sent to employee and management 

representatives at the requesting company, the state health 

department, and the OSHA Regional Office. This report is not 

copyrighted and may be freely reproduced. The report may be 

viewed and printed at www.cdc.gov/niosh/hhe/. Copies may be 

purchased from the National Technical Information Service (NTIS) 

at 5825 Port Royal Road, Springfield, Virginia 22161. 

Health Hazard Evaluation Report 2009-0214-3153 Page 97 
Below is a recommended citation for this report:

NIOSH [2012]. Health Hazard Evaluation Report: An evaluation of preventive 

measures at an indium-tin oxide production facility, Rhode Island. Morgantown, 

WV: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, HETA No. 

2009-0214-3153.

To receive NIOSH documents or information about 

occupational safety and health topics contact NIOSH at:

1-800-35-NIOSH (1-800-356-4674)

Fax: 1-513-533-8573

E-mail: pubstaft@cdc.gov

or visit the NIOSH web site at:

http://www.cdc.gov/niosh/hhe

Delivering on the Nation’s promise:

Safety and health at work for all people

through research and prevention.

 National Institute for Occupational 

Safety and Health