Engineered Nanomaterials


Problem:

Workers who construct and refurbish concrete and asphalt roadways may face hazards from engineered nanomaterials.


Risk Description:

Engineered nanomaterials are man-made materials manufactured at a very small size (from 1 to 100 nanometers or so, roughly 100,000 times thinner than a human hair). At this very small size, they can create unique and beneficial properties when added to construction products. These products are also called nano-enabled. Most engineered nanomaterials have not been tested to determine if they are toxic. Some nanomaterials may be safe but others have been shown to be hazardous. Breathing in dust and other aerosols containing engineered nanomaterials is the major exposure of concern for construction workers. Research suggests that engineered nanomaterials are unlikely to penetrate the skin, unless the skin is damaged.

There is no evidence yet that engineered nanomaterials have caused harm in exposed workers. Based on studies with laboratory animals however, long thin fibers called carbon nanotubes (CNT) can cause inflammation and scarring of the lungs. Multi-walled carbon nanotubes (MWCNT), a specific form of carbon nanotubes, have also been shown to cause cancer, including mesothelioma which is a type of cancer caused by asbestos.  In 2014, the World Health Organization – International Agency for Research on Cancer (IARC) classified MWCNT-7 as “possibly carcinogenic to humans.” Nano-size ultrafine titanium dioxide has also been found to cause inflammation of the lungs and lung cancer in lab animals. The National Institute for Occupational Safety and Health (NIOSH) has determined that ultrafine titanium dioxide should be considered a potential occupational carcinogen.  In 2006, IARC classified titanium dioxide as "possibly carcinogenic to humans."

The following documents from NIOSH provide additional information on the hazards and risks of carbon nanotubes and nano-size ultrafine titanium dioxide:


Level of Risk:

Very little is known about the level of health risk that engineered nanomaterials may pose to construction workers. Engineered nanomaterials can be released into a worker’s breathing air from nano-enabled construction products depending on the line of work being performed, the task being conducted, and tools that are used. Exposures to construction workers generally increase the more any construction product is disturbed. It is most important that exposures be limited and that precautionary approaches be used to reduce exposure and protect construction workers from the potential hazards of engineered nanomaterials.

Epidemiological studies of workers exposed to titanium dioxide show no clear evidence of increasing the risk of developing lung cancer or other lung diseases. None of these studies, however, involved construction workers who handle or use materials containing titanium dioxide.

So far, no epidemiological studies have been conducted on any worker population exposed to carbon nanotubes.

Based on animal studies using carbon nanotubes, NIOSH estimates that the risk of developing slight or mild lung effects over a working lifetime if workers were exposed to CNT at the Recommended Exposure Limit (REL) of 1 µg/m3 to be approximately 0.5%.

Based on animal studies using ultrafine titanium dioxide, NIOSH estimates that the risk of developing lung cancer over a working lifetime if workers were exposed at the REL of 0.3 mg/m3 is below 1 in 1,000.


Assessment Info:

CPWR – The Center for Construction Research and Training has a web site called eLCOSH Nano that lists and describes more than 500 construction products that may be nano-enabled, including adhesives, cement, coatings, drywall, flooring, insulation, lubricants, patching compounds, roofing and other construction materials.  You can use this site to see if any of the construction products you use are nano-enabled.


Regulations & Standards:

OSHA has no specific regulation or Permissible Exposure Limit (PEL) for any engineered nanomaterial.

NIOSH has an REL for carbon nanotubes of 1 µg/m3 elemental carbon as a respirable mass 8-hour time-weighted average (TWA) concentration for up to a 40-hour week. NIOSH also has an REL for ultrafine titanium dioxide of 0.3 mg/m3 as a time-weighted average (TWA) concentration for up to 10 hours/day during a 40-hour week.

The OSHA respiratory protection standard under 29 CFR 1926.103 would apply for construction workers exposed to engineered nanomaterials from nano-enabled construction products.

For engineered nanomaterials that have been found to be hazardous, OSHA’s hazard communication standard under 29 CFR 1926.59 would apply, including training for construction workers and access to Safety Data Sheets (SDS) for the nano-enabled product.

Federal OSHA has identified other of its standards that may apply to engineered nanomaterials.

Federal OSHA Standards are enforced by the U.S. Department of Labor in 26 states. There are currently 22 states and jurisdictions operating complete State plans (covering both the private sector and state and local government employees) and 5 - Connecticut, Illinois, New Jersey, New York and the Virgin Islands - which cover public employees only. If you are working in one of those states or jurisdictions you should ensure that you are complying with their requirements.

Federal OSHA Standards are enforced by the U.S. Department of Labor in 26 states. There are currently 22 states and jurisdictions operating complete State plans (covering both the private sector and state and local government employees) and 5 - Connecticut, Illinois, New Jersey, New York and the Virgin Islands - which cover public employees only. If you are working in one of those states or jurisdictions you should ensure that you are complying with their requirements.


Other Considerations:

There is no evidence at the present time that workers exposed to engineered nanomaterials have experienced harmful health consequences to themselves, but laboratory animal testing has shown that some engineered nanomaterials can be hazardous. That makes it important to consider conducting medical screening and hazard surveillance of workers who may be exposed to engineered nanomaterials. NIOSH has issued a document to help employers and workers implement such a program: Current Intelligence Bulletin 60. Interim Guidance for Medical Screening and Hazard Surveillance for Workers Potentially Exposed to Engineered Nanoparticles (NIOSH Pub# 2009-116).

When workers are exposed to engineered nanomaterials, NIOSH provides general guidance that recommends that employers conduct hazard surveillance to identify and document the presence of engineered nanomaterials in their workplaces, the work tasks involved with them, and the control measures that can effectively protect workers from hazardous exposures. NIOSH also recommends establishing medical surveillance to detect early signs of work-related illness and disease. Medical surveillance elements typically include medical and occupational histories, initial and periodic medical examinations, specific medical screening tests when necessary, post-incident examinations following uncontrolled or non-routine increases in exposures, and worker training to recognize symptoms of exposure to a particular hazard.

Due to insufficient evidence of harm to workers, NIOSH does not recommend any specific medical tests for workers exposed to engineered nanomaterials except for workers exposed to carbon nanotubes. For carbon nanotubes, NIOSH believes that exposed workers may be at risk of experiencing harmful effects to the lungs and recommends an initial evaluation that includes a spirometry test and a baseline chest X-ray with periodic evaluations to be performed at regular intervals. Additional details on the specifics of medical testing for workers exposed to carbon nanotubes can be found in the NIOSH Current Intelligence Bulletin 65. Occupational Exposure to Carbon Nanotubes and Nanofibers.