Should workers who are potentially exposed to engineered particles undergo surveillance and screening for the health effects of such particles?

The answer, according to Dr. Doug Trout, is a work in progress.

As a key contributor to the nanotechnology research center of the National Institute for Occupational Safety and Health (NIOSH), Trout participated in a roundtable discussion today on nanotechnology as part of AIHce 2011.

The number of U.S. workers who are being exposed is small, at present – approximately 620 – but is expected to increase rapidly, as the commercially attractive field of nanotechnology grows.

“We are all very interested in prevension,” said Trout. “The issue is how to apply medical monitoring to workplaces where exposure may be present.”

A few of the complicating factors in designing epidemiological studies to help make that determinination:

• The heterogeneity of nanoparticles, which Trout referred to as “a very large universe,” with an estimated 50,000 types of carbonaceous particles alone
• The difficulty of identifying a study population
• What are exposure characterizations?
• What are the disease endpoints?
• How would such studies be designed and analzed?

In “Medical Screening and Surveillance for workers Potentially Exposed to Nanomaterials,” Trout said, “Surveillance and screening are important and accepted components of a sound occuapational health program.” However, with toxicology research into the possible health implications of nanoparticle exposure still at an early stage, NIOSH currently has inadequate data to recommend medical screening.

NIOSH does, however, recommend taking prudent measures to control exposures and conduct hazard surveillance.

Trout pointed to growing evidence that exposure to carbon nanotubes and nanofibers is linked to lung inflammation, fibrotic responses, genotoxicity such as abnormal chromosome numbers, chronic obstructive pulmonary disease and cancer (i.e. mesothelioma).

“This is really a topic of debate within NIOSH now. We’re asking for public comment on what type of screening should be recommended for this type of exposure.”

Current draft recommendations call for medical monitoring of workers exposed to equal to or greater REL, and workers with the potential for intermittent elevated carbon concentration exposure.

Nano risk assessment would include the taking of a medical history, a physical examination and testing such as spirometry and chest x-rays. “We are recommending periodic evaluations,” said Trout, although he noted that the interval of such evaluations has yet to be determined.

Exposure registries – the collection and maintenance of records -- could be valuable tools in understanding nano exposure risk, although who would fund them, manage them and have access to them are questions that would ultimately need to be answered.