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NORA Manufacturing Sector Strategic Goals

927ZJEH - Exposure Assessment for Toxicologically-Important Chemicals.

Start Date: 4/1/2009
End Date: 9/30/2010

Principal Investigator (PI)
Name: Cheryl Estill
Phone: 513-841-4476
Organization: NIOSH
Sub-Unit: DSHEFS
Funded By: NTP

Primary Goals Addressed
6.0 9.0

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

The purpose of this study is to characterize workplace exposures to 1) welding fumes with emphasis on manganese, 2) indium and indium compounds, 3) diacetyl, 4) 2-methoxy-4-nitroaniline, and 5) 2',2'''-Dithiobisbenzanilide. These chemicals have been nominated by various groups to the National Toxicology Program. We will identify possible candidate industries, labor unions, workplaces, and uses and users; determine if there is relevance for occupational health; estimate number of workers exposed; and perform limited workplace exposure sampling. For some chemicals we will also initiate research for analytical methods development.


This project will characterize workplace inhalation exposures to 1) indium and indium compounds, 2) 2-methoxy-4-nitroaniline, 3) 2',2'''-Dithiobisbenzanilide 4) diacetyl, and 5) welding fumes with emphasis on manganese. For these chemicals we will perform selected tasks including:

1.Identify worker populations at elevated risk of exposure during a manufacturing process, and recruit workers from manufacturing facilities for inclusion in the study;

2.Develop a NIOSH analytical method for quantitatively assessing DTBBA, 2M4N, and Manganese valance states;

3.Characterize industry wide occupational exposures including total number of workers and evaluate patterns of exposure (using available industrial hygiene sampling methods, e.g., including video exposure monitoring, and the newly developed laboratory analysis methods);

4.Provide appropriate recommendations based on the analytical results for reducing exposure including engineering controls and work practice interventions.

During FY10, worker populations will be further identified for DBBTA and 2M4N including industry sectors and likely study sites. We will finalize analytical methods for 2M4N and DBBTA and conduct walk through visits. For Welding, the Manganese analytic method will be further enhanced and site visits will be conducted. Site visits will be conducted for Indium. The National Toxicological Program is an external partner and funds this research in part.


The objective that this research will work towards is, “Manufacturing Goal 6.1.2. - Conduct and promote exposure assessment of known and suspected carcinogens in manufacturing settings". The results of this research will determine if workers are exposed to these chemicals and assess exposures. In the meantime, the NTP is determining through animal studies the toxicity of these chemicals and the health endpoint. Three of these are suspected carcinogens. This work will enable NIOSH and other organizations to determine whether or not health studies should be conducted on these chemicals. We will work directly with the NTP to make sure that our findings are adequately described on their website and in any press releases. The following methods are being used to substantiate these intermediate goals: conducting exposure assessments across the industry to determine worker exposures to these possible carcinogens. This research will add to the knowledge of exposures in these industries to establish current exposure levels to these chemicals in manufacturing.

The diacetyl work relates to the Respiratory Disease Strategic Goal #1, "and reduce work-related airways diseases”. The welding exposure assessment work relates to the Respiratory Disease Strategic Goal #5, "Prevent respiratory and other diseases potentially resulting from occupational exposures to nanomaterials." Both the diacetyl and welding exposure assessment research relate to manufacturing goal # 5, "Reduce the number of respiratory conditions and diseases due to exposures in the manufacturing sector." Methods being used to substantiate these goals include: 1) exposure to diacetyl may cause lung disease and this study will establish current exposures in food processing industries to assist in recommending ways to reduce exposure which, in turn, leads to prevention of respiratory disease; 2) exposure to manganese in welding may also lead to respiratory disease and this study will assess current exposures in industry with specific emphasis on nano-sized particles.

Mission Relevance

This is a collection of exposure assessment studies which include determination of approximate number of workers exposed,
and measurement of exposures at typical tasks and development of an air sampling analytical method, if needed. Five high
priority chemicals will be studied: indium and indium compounds, 2-methoxy-4-nitroaniline, 2',2'''-Dithiobisbenzanilide, diacetyl,
and welding fumes with emphasis on manganese (Mn).
Indium tin oxide (ITO) is used in the manufacture of flat panel displays. Indium phosphide (InP) is used in the production of
semiconducting materials, although the extent of use is unknown. Indium or indium compounds are also reportedly used in
optoelectronics (including photovoltaics), solders, alloys, radiopharmaceuticals for biomedical imaging, and in nanomaterials,
such as quantum dots. The number of workers exposed is unknown.
2-MeO-4-NA is used in the production of certain dyes. This chemical lacks toxicology and carcinogenicity data, has positive
mutagenicity data, and has been determined to be closely related to the chemical, 2-methoxy-5-nitroaniline, which was a multisite
carcinogen when tested by the NTP. Use of 2-MeO-4-NA appears to be on the rise in the U.S.
DTBBA is used mainly as a peptizing agent (plasticizer) that allows natural and synthetic rubber to be shaped and molded into
final end products, such as tires, belts, hoses, and various other components. Occupational exposures in rubber manufacturing
workers include dermal and inhalation routes during the compounding and mixing process. Toxicity and carcinogenicity is
unknown, and use of this chemical is increasing.
Flavored food production is the process of manufacturing food and beverage products with flavorings added to enhance or
modify the taste of the product. Occupational exposures in the food production industry have been associated with respiratory
disease, including bronchiolitis obliterans (BO), an uncommon lung disease characterized by fixed airways obstruction. A review
of common ingredients listed diacetyl among other flavorings and recent attention has been focused on diacetyl as the potential
cause of bronchiolitis obliterans.
Welding is the process that joins metals using extreme heat produced by electric current,generating a complex, nanometersized
aerosol consisting of the base and electrode metals which often includes Manganese (Mn). Research is needed to
determine critical information pertaining to welding fume (WF) exposure and the risk of developing parkinsonism-the physical
manifestation of a neurological syndrome resembling Parkinson’s disease, and Manganism, a form of Parkinsonism resulting
from high Mn exposures that has been observed in ore mining and refining, ferro-alloy production, and dry cell battery industries.
The International Agency for Research on Cancer (IARC) has classified indium phosphide as probably carcinogenic to humans
(Group 2A) based on a determination of sufficient evidence of carcinogenicity in animal experiments.
2-MeO-4-NA was nominated for testing in 2006 by the National Cancer Institute for toxicology and carcinogenesis studies under
the National Toxicology Program (NTP) based on the high and increasing national aggregated annual production volume, the
potential for worker exposures, and the lack of adequate data.
2',2'''-dithiobisbenzanilide (DTBBA) was nominated in 2007 by the National Cancer Institute for National Toxicology Program
(NTP) toxicology and carcinogenesis studies. The nomination was based on high and increasing production volume, the potential
for occupational and consumer exposures, the lack of adequate toxicology and carcinogenicity data, and the suspicion of toxicity
based on the structure of the chemical.
Under NAICS 311, nearly 1.5 million workers are employed in food manufacturing with the subcategories that likely include
flavorings in their products: 287,800 in Bakeries and Tortilla Manufacturing (NAICS 3118), 154,100 in Other Food Manufacturing
(NAICS 3119), 132,000 in Dairy Product Manufacturing (NAICS 3115), and 83,700 in Sugar and Confectionery Product
Manufacturing (NAICS 3113). Employers are generally small businesses with 89% employing less than 100 workers, and nearly
53% employing less than 10 workers (U. S.Census Bureau 2004).
In 2007, the Bureau of Labor Statistics estimated that 386,000 U.S. workers were employed as welders, cutters, solderers, and
The indium project will provide information on workers’ exposure to indium so that the NTP can make determinations on further
study and issue a comprehensive report which includes workers’ exposures.
There are limited environmental and occupational exposure data available for 2-MeO-4-NA and DTBBA in the scientific
literature to assess the acute exposure/response relationship. This study will provide NTP information on use of these chemicals
in the U.S., approximate numbers of workers exposed, and exposure levels for certain processes.
The flavorings project will determine which food manufacturing industries use diacetyl, how it is used, worker exposures for
certain processes, and approximate numbers of workers exposed. This research will enable NTP and OSHA to make
determinations regarding next steps in toxicology research and/or rulemaking.
The Welding Fume study will provide exposure information on Manganese in welders conducting different processes. It will
isolate the Mn+2 valance state suspected to be related to the health effects. These data will enable NTP to make toxicological
decisions in their final report and report numbers and types of exposed workers.