35. Engineered nanomaterials in the U.S. construction industry

Nanomaterials are approximately 1 to 100 nanometers, which is incredibly small (1 nanometer is about 100,000 times thinner than a sheet of paper). At this size, materials can exhibit unique properties, which have enabled recent advances in construction materials.¹ Nanomaterials can be naturally occurring, incidental, or engineered. Incidental nanomaterials are unintended by-products of human activities, including work tasks like welding or sandblasting that create ultrafine particles. Engineered nanomaterials (ENM), on the other hand, are created intentionally by humans for some purpose.

Human health effects caused by ENM exposure are currently unknown. Nevertheless, characteristics of ENMs and their similarities to tiny particles found in air pollution suggest that ENMs are likely to pose health risks to humans.² There are many different ENMs, and their toxicity varies. Some ENMs have been shown to cause health problems in laboratory animals, including certain types of carbon nanotubes with characteristics similar to those of asbestos fibers. Citing these types of studies, the National Institute for Occupational Safety and Health (NIOSH) established recommended exposure limits for carbon nanotubes/nanofibers and nano-sized titanium dioxide particles, classifying the latter as a potential occupational carcinogen.^3,4

In recent years, nanotechnology has improved traditional building materials, resulting in nano-enhanced or nano-enabled products (NEPs). For example, carbon nanotubes have been added to concrete for increased strength. Out of 557 NEPs identified by CPWR researchers, most (57.5%) were paints and coatings, followed by a variety of construction materials (chart 35a). This information about the use of ENMs in construction has helped researchers to measure exposures to ENMs during routine construction activities (e.g., coatings application, wood sanding, and roofing work).^5,6

In most cases, however, construction product manufacturers in the United States are not required by law to inform workers and consumers about the presence of ENMs in final products, making it difficult to identify construction materials with added ENMs. Out of 577 nanomaterials reported in CPWR’s Electronic Library of Construction Occupational Safety and Health (eLCOSH) nano inventory, 238 (41.3%) were of undetermined chemical composition (chart 35bb). Moreover, construction workers, like the general public, may have limited awareness of nanotechnology. Out of 96 construction health and safety trainers surveyed by CPWR from 2014 to 2017, fewer than half (47.9%) were aware that nanotechnology has been applied to construction materials (chart 35c). A smaller percentage of those surveyed (<13%) knew of NEPs being used on actual jobsites or had addressed nanotechnology while training workers. Insulation and cement were mentioned most frequently with regard to actual use of NEPs on construction sites. Training materials for construction workers handling NEPs are available, including hazard alert cards (/research/research-to-practice-r2p/r2p-library/hazard-alert-cards/) and toolbox talks (/toolbox-talks). These resources emphasize that ventilation and respirators can reduce exposure to ENMs during routine construction activities.

A primary goal of the U.S. federal government’s National Nanotechnology Initiative (NNI; http://www.nano.gov) is responsible development of nanotechnology, including protection of workers throughout the life cycle of nanotechnology-derived products. Most NNI research on environment, health, and safety falls within its own investment category, accounting for approximately 5.5% of the $1.2 billion of proposed NNI funding for 2018 (chart 35d). NIOSH participates in the NNI as one of the leading federal agencies for occupational safety and health. The NIOSH Nanotechnology Research Center, established in 2004, has already made significant progress in achieving its strategic goals, including the creation of risk management guidance for the nanomaterial workforce.⁷

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