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workers, building, architect

NORA Manufacturing Sector Strategic Goals

9270099 - Control of Styrene Exposure in Boat Manufacturing

Start Date: 10/1/2004
End Date: 9/30/2009

Principal Investigator (PI)
Name: Duane Hammond
Phone: 513-841-4286
Organization: NIOSH
Sub-Unit: DART
Funded By: NIOSH

Primary Goal Addressed

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

Styrene is a fugitive emission and a result of evaporation from resins, gel coats, solvents, and surface coatings used in the fiber reinforced plastics (FRP) boat manufacturing process. This project will 1) assess the effectiveness of closed molding for controlling occupational styrene exposures; 2) assess the effectiveness of the Maximum Achievable Control Technology (MACT) mandated measures in open molding for controlling occupational styrene exposures; and 3) develop cost-effective control measures for controlling occupational styrene exposures in open molding processes. While closed molding is currently being used by the larger boat manufacturers, open molding is still used across the entire spectrum of boat manufacturers, including the smaller operations. Dissemination of the study findings will be done in consultation with the National Marine Manufacturers Association (NMMA), a vital partner in this project.


In the early 1980s, NIOSH conducted a control technology assessment of the boat manufacturing industry, primarily focusing on large fiber reinforced plastic (FRP) boats using open molding techniques. Since then, many changes have occurred in this industry, including the development closed molding and the promulgation of EPA's MACT standard for boat manufacturing. The MACT standard requires boat manufacturers using open molding to adopt specific control technology to control environmental releases of styrene to the environment.

The primary aims of this project are: 1) to complete assessment of closed molding processes in fiber-reinforced plastic (FRP) boat manufacturing and the associated occupational exposure to styrene; 2) to assess the effectiveness of the Maximum Achievable Control Technology (MACT) standard mandated controls for controlling occupational exposures to styrene during open molding of FRP boats; and 3) to develop cost-effective ventilation controls for reducing styrene exposures in open molding FRP boat manufacturing processes. The outcome of this study will be evaluated in terms of personal exposures of workers who operate the equipment, laborers who work alongside the operators, and by measuring emissions from styrene sources at various locations throughout the facility under study (area samples). For this project, effective environmental controls are those that maintain styrene exposures below the occupational exposure limit (in this case the NIOSH recommended exposure limit (REL) or the OSHA permissible exposure limit (PEL)).

The long-term goals of this project are to reduce worker exposures to styrene by providing data to support the development of the closed-mold process, to determine if the engineering controls applied in the open mold plants are adequate, and to develop a set of recommendations to improve the effectiveness and efficiency of control measures

This study will be conducted in phases. Phase 1 was completed in FY05 and FY06. This phase included partnership developments, six walk-through surveys, and project planning. Phase 2 was also completed in FY06, and focused on the project protocol and peer review. The project protocol was approved by HSRB and completed in FY07. Phase 3 involved in-depth surveys of the closed molding process, and was conducted during the late summer of FY06 and early FY07. Phase 4 will be the evaluation and intervention study of ventilation for open molding processes. Phase 4 of the project may occur simultaneously with Phase 3. Additional surveys could be conducted during FY07 to assess the similarities and differences between the boat manufacturing facilities and other FRP manufacturing operations. Project reports, articles and other products will be completed during FY07.


1) Complete assessment of closed molding processes and the associated occupational exposures to styrene. 2) Assess effectiveness of MACT standard mandated controls for controlling occupational exposures to styrene. 3) Develop cost-effective ventilation controls for reducing styrene exposures in open molding processes. 4) Transfer information learned in this study to the FRP boat manufacturing industry. 5) Transfer information from the FRP boat manufacturing industry to other FRP manufacturing industries.

Mission Relevance

NIOSH estimates at least 30,000 U.S. workers are potentially exposed to styrene on a full-time basis, while more than 300,000 workers are potentially exposed to compounds containing styrene. According to the 2001 Statistics of U.S. Businesses, approximately 54,500 workers were employed in the boat manufacturing industry, with 26,000 in firms of 500 employees or less. The research in this industry is of high importance due to the documented amount of styrene exposed workers and the potential carcinogenic effect styrene can have on exposed individuals. The goal of this project is to assess the effectiveness of closed molding processes. Meetings with industry trade association (IBEX Conference 2003) and individual companies have shown an interest in a study to assess the effectiveness of closed mold operations for reducing occupational styrene exposures. In addition, the trade association representatives have expressed interest in NIOSH developing cost-effective ventilation controls for open molding processes, recognizing that open molding represents the most common and highest exposure processes in their manufacturing facilities. Therefore, this project will include design and development of cost-effective ventilation systems for controlling styrene exposures in open molding processes. An economic analysis addressing implementation of engineering controls, capital investment effects, production frequency, and labor efficiency will be included in the design.

This project supports the NORA manufacturing sector strategic goal 4 of improving the understanding of occupational risk and protective factors in, and develop appropriate interventions for, the manufacturing sector through exposure assessment research. This project also relates to the manufacturing interim goal 1 of chemical exposure under strategic goal 4. The evidence based intervention of closed molding will be studied to show which closed molding technologies effectively reduce chemical styrene exposures of workers. This project relates to the cancer, reproductive, and cardiovascular disease cross sector strategic goal 1 and intermediate goal 1.2g of developing control technologies such as closed molding to reduce carcinogenic risk. This project will also meet the NORA engineering control emphasis area goal 2 of developing and evaluating new or modified engineering controls and promote the transfer of effective engineering control measures for safeguarding worker health. The effectiveness of the engineering control of closed molding for boat manufacturing will be evaluated for the effectiveness of safeguarding worker health by reducing worker exposures to styrene.