By Mike McNulty, Rubber & Plastics News
Milwaukee, Wisconsin -- The chemical curing agent that pole-vaulted the Polyurethane Manufacturers Association into national prominence decades ago is back in the forefront again, only this time without the hype.
The curative 4,4'-methylene-bis (2-chloroaniline), known as MOCA, was the centre of controversy on and off for two decades and set off a long battle between the PMA and the Occupational Safety and Health Administration in 1973 -- two years after the PMA was formed. At that time, OSHA put MOCA on a list of chemicals it designated as possibly causing cancer.
For years, Milwaukee-based PMA found itself on the front lines squaring off with OSHA and other federal agencies at hearings in Washington over the MOCA issue. The association prevailed in most cases, but US agencies closely regulate the agent today.
However, early on the PMA recognised the potential for dermal absorption of MOCA and for almost 20 years has been monitoring and setting best practice guidelines for its members, according to Don Gallo, the association's attorney.
So PMA members were surprised, he said, by the results of a study in November 2007 on MOCA handling practices published by England's Health and Safety Executive, a government agency. Because the HSE's guidelines differed from the PMA's MOCA Use Guidance document posted in 2005, the association launched its own independent review, conducted by researchers at Benedictine University in Lisle, Illinois
The organisation's goal was to determine if voluntary member guidelines were sufficient in reducing the exposure to MOCA.
Results from the recently released study show that MOCA handling practices employed by PMA member companies yielded a similar or better level of protection than the regulatory approach defined by the HSE, the association said.
While MOCA can be absorbed through the skin when employees have direct contact to the cast urethane process, the study revealed that new technology has been successful in dramatically reducing an employee's risk by using computer systems that melt, weigh and dispense the agent.
Historical urinalysis data demonstrates that companies that regularly perform tests kept their exposure levels well below recommendations pushed by agencies in both England and California over the last 20 years.
The study recommended that processors should be educated on the importance of proper spill response and periodic wipe sampling of potentially contaminated surfaces. In addition, it said periodic urinalysis should be done by all processors using the agent and additional urinalysis should be performed to detect potential MOCA dermal exposure from handling partially cured polyurethane articles.
The PMA study "highlights the work of our PMA member companies in reducing exposure of MOCA in their work environments," Gallo said. "We are committed to looking for ways to utilise the findings from the research to set new guidelines that will further reduce member employees' exposure to the chemical curing agent and the cast urethane process."
Data for the study was gathered from 20 participating PMA member companies through an extensive survey, the association said, adding that 14 firms supplied historical urinalysis data to be reviewed and studied. Researchers randomly visited the plants of four companies to determine how PMA guidelines were being implemented.