Protect your workers from exposure to nano hazards
Understand the properties of the materials being used.
Nanotechnology – the manipulation of matter on a near-atomic scale – is used in a growing number of applications. They include computer hard drives using the magnetic properties of nanoparticles to store more data on much smaller devices, water filtration systems, protective and glare-reducing coatings for eyeglasses and cars, stain-free clothing and new medical treatments.
Nanomaterials are extremely small with dimensions roughly between one and 100 nanometres (nm). A nanometre is one billionth of a metre. For example, a human hair is about 70,000 to 80,000 nm, a red blood cell is about 7,000 nm and a virus is about 10 to 100 nm.
Nanomaterials can have unique physical, chemical and biological properties that make them useful in a wide variety of applications, such as making stain-free textiles using nanoscale additives or surface treatments, or targeting drugs selectively to cancerous cells.
As applications move from laboratories to industrial settings, workers and employers should be aware of potential hazards and adopt appropriate measures to control exposure through inhalation, skin contact or ingestion.
Much of the information available about specific hazards is incomplete. Nanoparticles are generally more toxic than a larger dimension of the same chemical substance, but it’s impossible to determine by how much due to a lack of exposure data.
Nanoparticles appear to enter the body through inhalation, ingestion or absorption through the skin. Some studies have shown as particles become smaller, the likelihood of injury to occur increases.
Nanomaterials are most likely to enter the body through the respiratory system if they are airborne and in respirable-sized particles, ending up in all areas of the respiratory tract, depending on their size and composition. From there, they enter the blood and lymph circulation systems, and are then distributed throughout the body. Once in the blood system, the liver, spleen, bone marrow, heart and other organs can absorb them.
Research into skin absorption suggests if it occurs, the amounts will be low.
It’s important during a risk assessment to understand the hazardous properties of the material. Since there is a limited amount of hazard data available, it’s challenging to establish the toxicological behaviour of specific materials with any degree of certainty. In most cases, it will be necessary to refer to information obtained for similar materials. In this case, establish that the information you find is relevant for the material being used. Safety data sheets are useful for this purpose.
Combine the following measures and best practices to control potential exposures:
Elimination. Getting rid of hazardous substances, including nanomaterials from processes and products, is the most effective control.
Substitution. Use a non- or less-hazardous substance, or a different and safe technology.
Engineering controls. NIOSH states “current knowledge indicates that a well-designed exhaust ventilation system with a high-efficiency particulate air (HEPA) filter should effectively remove nanomaterials.” Where operations can’t be enclosed, provide local exhaust ventilation equipped with HEPA filters, and design it to capture the contaminant at the point of generation or release.
Administrative controls. Establish procedures to address cleanup of nanomaterial spills and decontamination of surfaces. For example, prohibit dry sweeping or use of compressed air for dust cleanup. Use wet wiping and vacuum cleaners equipped with HEPA filters. Prevent the consumption of food or beverages in workplaces where nanomaterials are handled, and provide facilities for hand washing, showering and changing clothes. Separating eating rooms and changing facilities are also good options.
Personal protective equipment (PPE). Provide appropriate personal protective equipment such as respirators, gloves and protective clothing. Use PPE when other measures are insufficient or not feasible. HEPA filters, respirator cartridges and masks made with fibrous filters, protective clothing, goggles and gloves can be used. Filtering half masks have to fit properly. Protective clothing made from airtight, non-woven textile are more effective than cotton and polypropylene. Nitrile, latex and neoprene gloves are effective for nanoparticles with a 10-nm diameter when exposing the glove for a few minutes. Workers should be informed of the protective equipment’s limits, its validity and correct use.
Nanotechnology safety doesn’t need to be complicated. Worker exposure will be minimized if each step of the manufacturing operation is enclosed and the appropriate controls are in place.
The Canadian Centre for Occupational Health and Safety (CCOHS) in Hamilton contributed this article. CCOHS provides information, training, education, management systems and solutions that support health and safety programs and the prevention of injury and illness in the workplace. Visit www.ccohs.ca.
This article appeared in the October 2019 print edition of PLANT Magazine.