Narrowing in on nanoparticles

Workers in manufacturing can encounter a range of hazards on the job, but some of those dangers can pass unseen. Such is the case with nanoparticles, so tiny they can be inhaled and put workers at risk for various ailments, including lung cancer.

University of Iowa researchers, led by Tom Peters, associate professor of occupational and environmental health in the UI College of Public Health, have created a device that can detect certain nanoparticles, such as titanium dioxide, and workers’ exposure to them. The device is called the personal Nanoparticle Respiratory Deposition sampler.

The lightweight sampler, about the size of a deodorant stick, is worn on the lapel of a worker’s outfit. Air passes through the three-stage device, which collects particles smaller than 300 nanometers, mimicking the particles that normally deposit within an individual’s respiratory system.

The sampler has wide applicability beyond engineered titanium dioxide, used in the manufacture of paints and plastics, for which it was originally developed. Peters recently filled an order for the samplers from the U.S. Army, which is investigating the health effects of lead and copper nanoparticles emitted from weapons when they are fired.

With the aim of reaching a wider market, Peters and his colleague Lorenzo Cena are the inventors on a patent application that the University of Iowa Research Foundation has filed for the device. In addition, Peters has received funding through the Iowa Centers for Enterprise Commercialization GAP Fund Program to develop a disposable version of the sampler, with reduced production costs, so that the device can be sold commercially.

The challenge with detecting nanoparticles is their size. A nanoparticle measures less than 100 nanometers; a single nanometer is one-billionth of a meter, or roughly 1/50,000th of a human hair. Nanoparticles are more toxic than larger particles of the same material, studies suggest. As nanoparticle materials are used more frequently in manufactured products, they are becoming more common as an environmental contaminant for workers. However, conventional air sampling methods fall short when it comes to accurately assessing workplace exposure to ultrafine particles, says Peters.

“Conventional air samplers collect both nanoparticles and larger particles,” says Peters. “If the larger particles aren’t excluded, they can block the signal of nanoparticle presence and not fully describe risks to worker safety.”

Tom Peters

To design the sampler, Peters worked with Renée Anthony, UI assistant professor of occupational and environmental health, and Cena, at the time a doctoral student, now an associate service fellow with National Institute for Occupational Safety and Health at the Centers for Disease Control and Prevention.

“We recognized that a personal sampling method that removes larger respirable particles and collects only nanoparticles would streamline exposure assessment,” Peters says. “By capturing only nanoparticles on the sampling media, cost-efficient bulk chemical analysis techniques could be used to estimate their deposition in the respiratory system.”

Peters points out that sampling with conventional methods requires analysis by electron microscopy at a cost of about $300 per sample, while chemical analysis for his team’s device is about $30 per sample.

“Currently, we’re developing analysis methods for metals or metal oxides, including engineered nanoparticles and incidental nanoparticles, such as metal fumes from welding and exhaust from diesel combustion,” Peters says.

At NIOSH, Cena is using the sampler to investigate manganese and hexavalent chromium nanoparticles emitted during mild steel (a commonly used, low-carbon steel) and stainless steel welding. Manganese has been associated with neurological disorders, while hexavalent chromium is associated with lung cancer and asthma.