Case Study 8:
Control of Lead Exposure in a Foundry
Description of Operation
The facility is a foundry that makes automatic diesel engine blocks using both cupola and induction melting processes. The facility purchases various forms of scrap metal from scrap metal suppliers, re-melts the scrap, and pours it into engine block molds. After cooling, the casts are machined before being sent to the engine assembly facility.
Some of the scrap metal purchased from scrap vendors contained lead bearings and bushings, structural steel scrap with lead-based paints, and chunks of lead-containing materials. The melting of lead-contaminated scrap creates airborne lead exposure to employees as well as poor casting quality. As a result of the employee lead exposures, the company instituted a series of changes in its IH program including a medical surveillance program to monitor employee blood lead levels. A respiratory protection program was also initiated to protect employees who worked in the melting and metal pouring processes from overexposure to lead.
The foundry was faced with either continuing to implement a more stringent lead exposure control program or finding another means of eliminating the lead in the process. In addition to medical surveillance and PPE the facility was also faced with the prospect of expensive engineering controls to control lead exposures. As an alternative, a process was developed ensure that suppliers supplied scrap metal that was free of lead contamination. Such a purchasing specification existed but was ineffective and required changes that included the aggressive enforcement of the supplier scrap procurement requirements and the use of internal scrap inspection procedures.
Impacts of the Intervention
As a result of the aggressive purchasing specifications and increased inspections of incoming scrap metal, the melting and pouring processes were maintained free of any significant employee airborne lead exposures. Medical surveillance demonstrated that there was no lead detected in employee blood tests and the need for respiratory protection for lead exposure in manufacturing operations was eliminated.
The option to focus on the elimination of lead versus providing employee protection and engineering controls resulted not only in higher levels of employee protection, but also in millions of dollars in savings for the facility. Given the strong competitive pressures in the industry, it is possible that eliminating the hazard through stringent purchasing controls helped to keep the facility viable and saved hundreds of jobs.
The elimination of lead in the scrap metal feed stock also resulted in the prevention of lead from being introduced to the cast engine blocks. Any significant amount of lead in the engine blocks would degrade the overall strength of the casting. Previous quality problems that resulted from lead contamination had been noted.
A retrospective ROHSEI analysis was computed for the actual costs associated with the purchasing controls versus the potential costs associated with enhanced respiratory protection and engineering controls. Improving the purchasing controls and enhanced inspections required the hiring of additional inspectors, rewriting scrap specification procedures, and retraining of management and employees. The 5-year cost was a net present value (NPV) of ($1,125,347). The estimated 5-year cost associated with enhanced employee respiratory protection and significantly upgraded exhaust ventilation was a net present value (NPV) of ($20,735,212). Thus the option to eliminate the exposure was both a far superior business option as well as an approach that virtually eliminated employee lead exposure and the associated health hazard.
At this facility, management recognized the threat that lead contamination presented to the employees and the product. Contracts with waste suppliers clearly stated the need to severely restrict any lead-containing materials in the scrap metal provided. However, there was reluctance by management to take firm action to control vendors due to the competitiveness of the scrap market and a concern about not receiving sufficient scrap to supply the facility.
The site IH professional served as the catalyst to drive management actions. Identification of employee health risks, as well as defining the necessary actions to control those risks via PPE and engineering controls, convinced management that firm action was needed to enforce contract provisions and implement stringent on-site scrap audits to verify supplier compliance with the contract provisions.