No elevated cancer risk for hard metal workers, says study

Lung cancer risk is not increased for those who work in the hard metal industry, according to study conducted in the US.

The study, conducted by the University of Pittsburgh Graduate School of Public Health, surveyed 32,000 workers across five countries.

It contradicted previous studies, which suggested that tungsten carbide with a cobalt binder — the primary ingredients in hard metal — may be linked to an increased risk of lung cancer.

“Our findings will affect regulatory agencies and how they set exposure standards,” said principal investigator Gary Marsh, professor of biostatistics at Pitt Public Health and director and founder of the school’s Center for Occupational Biostatistics & Epidemiology.

“It is very good news that the workers in this industry are not at increased risk of death due to the materials used in their occupation, both for the employees and for the hard metal industry.”

Because cobalt has been shown to cause cancer in animals and can be a serious lung irritant, workers wear closed hoods with full respirators when handling the powdered metals without technical controls.

While there was no increased risk of death on average for the hard metal employees — including those who had worked in the industry for decades or in the 1950s, before modern respirators — the researchers did find small excesses in lung cancer mortality among short-term workers who were employed in the hard metal industry for less than a year, compared with long-term workers.

“These findings in short-term workers are unlikely due to occupational factors in the hard metal industry,” said Marsh.

“Instead they are more likely due to differences in lifestyle and behaviour that could impact lung cancer risk, such as higher smoking rates.”

Additionally, median worker exposure levels for tungsten, cobalt and nickel were all below the American Conference of Governmental Industrial Hygienists’ threshold limit values for airborne concentrations of chemical substances, which is one set of standards recommended by the Occupational Safety and Health Administration.

Pitt Public Health coordinated the study, which involved workers at three companies and 17 manufacturing sites in the US, UK, Austria, Germany and Sweden, and led the analysis that combined the individual country findings. The research was initiated and funded by the International Tungsten Industry Association, which is the primary trade organisation for the hard metal industry. The Pennsylvania Department of Health also provided funding.

The results of the study will be published in an upcoming issue of the Journal of Occupational and Environmental Medicine as a series of eight articles.

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