Nanoparticles: The Next Asbestos?

 

September 11, 2018

Christine G. Barlow CPCU

Nanotechnology is relatively new technology with the potential for significant impact on society. While nanoparticles have been around for hundreds of years, the invention of microscopes that can see atomic size particles made it possible for scientists to develop a wide variety of uses.

 

Nanoparticles are extremely small; they are generally from 1 to 100 nanometers, and a nanometer is one billionth of a meter. A two-nanometer size particle is over ten billion times smaller than a red blood cell. A human hair is 20,000 nanometers. When materials are reduced to the nanoparticle level, they may have different properties such as increased strength or making coatings slipperier. This change in properties makes it possible to deliver medication to specific areas, create fabric that is stronger or that doesn't wrinkle, create medical bandages that fight bacteria and other applications.

 

Nanoparticles can enhance consumer products, advance medical treatments, improve building components, help in cleanup of contaminated sites, and offer additional benefits. However, one downside is that the small size of nanoparticles allows them to enter through the skin, enter the bloodstream and cross the blood-brain barrier, pass through lung tissue, affect cells, and accumulate in the air or soil among other potentially harmful effects. This possibility combined with the potential of the nanoparticles having different characteristics than the macroparticles raises some concerns about safety.

 

There are concerns that nanoparticles could lead to cancer. Toxicity depends on the type of nanoparticle and the type of exposure; nanoparticles embedded in final products such as fabric may cause no problems, while the inhalation of powder could lead to complications similar to those found with asbestos. Studies of titanium dioxide have shown that low toxicity particles of fine and ultrafine (nanoscale) sizes have shown pulmonary responses in exposed rats, including inflammation and lung tumors. Exposure to carbon nanotubes and nanofibers has shown similar results. While there is no hard evidence that exposure to nanoparticles can eventually lead to cancer, NIOSH has developed guidelines for workplaces to follow if employees are exposed to nanoparticles and posters that can be displayed in the workplace as well.

 

Dry powders present the most potential for exposure, either through the skin or through inhalation. Likewise, nanomaterials suspended in liquids have the potential for inhalation when in spray form. Various controls are recommended for various exposures. Fume hoods, ventilated bagging stations, exhaust vents, ventilated spray booths, downdraft tables and wet cutting/machining are all recommended ways to control exposure. The use of procedures when handling nanoparticles is recommended, as well as training workers on the risks of exposure and how to handle the materials. The use of personal protective equipment is recommended when other measures cannot guarantee safety. The use of gloves, lab coats or coveralls, safety glasses or face shields, and respiratory protection are all recommended for workers that may be exposed to the particles.

 

Exposure to asbestos is a known carcinogen, although it took several decades of exposure before bans were put in place. The Environmental Protection Agency banned it in 1989, overturned that ban in 1991 and put a new ban in place in 20007. The EU and France banned all forms of asbestos in 1998. The United States is considering allowing some specific uses of asbestos once again, even though new cases of mesothelioma, which is caused by exposure to asbestos, continue to occur.

Because of studies so far, the National Institute of Occupational Safety and Health (NIOSH) has set an acceptable exposure limit of one microgram/cubic meter of elemental carbon as a respirable mass eight-hour time-weighted concentration. Even so, the overall recommendation is to limit exposure for workers as much as possible.

 

Exposure of workers to nanomaterials is recommended to be controlled as much as possible. While the exposure to raw materials is different from exposure to sunscreen and other end products, the potential exists that nanomaterials may not be totally safe. A factory worker in 1898 warned of harmful effects of asbestos, and over subsequent years there were more suspicions linking asbestos to disease and death before countries finally banned it. What if it works the same way for nanoparticles, and not just for workers, but for consumers as well? One inventory lists 1827 products containing nanomaterials. Items range from sheets to bicycle cleaning kits to socks to hair dryers and lip balm, among others. With this wide range of products, the unknown aspect of whether or not nanomaterials do have detrimental effects, or might over long-term exposure, is significant.

 

Substantial product liability issues may arise. One factor of course will be which product the consumer was exposed to that caused the ill effects? With asbestos, the product exposure is limited. Nanoparticles could be in almost anything, and at the point of illness related to exposure, would the consumer have to prove that it was the lip balm and not the sheets or sunscreen that caused the illness, or would there be reasonable claims against all manufacturers on a proportional basis? The product liability exposure is enormous, and something the industry should look at going forward.