Flooring Products Hazard Spectrum

HBN ranks categories of flooring materials on a simplified spectrum.[1] Products in the green categories are better options than those in the orange or red, and products in the yellow categories are generally less preferable than those at the top, but are better choices than those at the bottom. Individual products can vary significantly in their health profiles, however there are some categories of flooring materials that generally come out ahead of others.

Flooring Products spectrum assumes that many flooring materials are manufactured with a protective topcoat, a standard practice in the industry.

The Flooring Products spectrum encompasses a wide variety of flooring options, including resilient, ceramic tile, and carpet. The spectrum excludes adhesives which may be required to install the products. Refer to the Flooring Adhesives Hazard Spectrum for guidance.

Many flooring materials are manufactured with a protective topcoat, a standard practice in the industry. While some ingredients in topcoats (polyurethane or epoxy-based resin hardened with aluminum oxide and exposure to ultraviolet light)[2] may have hazards throughout their life cycle, we have not considered their hazard contribution to the ranking of the flooring material itself because the topcoat is so prevalent across product types.

The primary health concern stemming from these coatings is for workers who would be exposed to the coating while it was wet in the factory. However, some products include nanomaterials in topcoats, and these may be a concern for residents as well. The National Institute for Standards and Technology (NIST) has raised concern that “substantial” amounts of nanomaterials in topcoats may be released via repeated mechanical forces such as walking on, mopping, and polishing floors. The federal agency is concerned that, “such release of the nanosize material is potentially harmful to the occupants, particularly children who typically experience greater exposure to substances deposited at floor level.”[3]

Given the widespread presence of topcoats and nanomaterials in resilient and wood flooring and ceramic tiles, it is not possible for consumers to avoid them at this time. Topcoats are a high priority for disclosure and hazard avoidance through green chemistry solutions.

There are many ways consumers can help. Encourage manufacturers to fully disclose the content (including topcoats, stain-repellant treatments, and antimicrobials) and associated health hazards for flooring products through the industry’s collaborative, user-designed open standard, Health Product Declaration (HPD).

Here are some general rules of thumb to use when choosing flooring materials:

  • Prefer non-vinyl flooring. Vinyl flooring has many life cycle concerns and also can contain many additives of concern. If possible, avoid materials that use vinyl. If you use vinyl flooring or carpet with vinyl backing, make sure it is free of hazardous phthalate plasticizers which can migrate from products and expose residents, particularly young children crawling on floors.

  • Avoid fluorinated stain repellents. Per- and polyfluoroalkyl substances (PFAS) are commonly used in stain-repellant treatments for carpets. This class of chemicals is a high priority to avoid because they can be toxic, persist in the environment, and build up in body tissues. Many new carpets are becoming available without these stain repellents.

  • Check the type and source of recycled content. Recycled content can add significant hazards to products if sourcing is unknown and screening is not performed. In particular, you should avoid fly ash, which is used as a filler in carpet backings, crumb rubber used in recycled rubber flooring, cathode ray tubes (CRTs) in ceramic tile, and post-consumer recycled vinyl which often contains legacy contaminants. See the hazard spectrum below for more information and resources.

  • Avoid products with high hazard antimicrobial additives, like triclosan (which is a PBT and suspected endocrine disruptor), or products that are marketed as having a health benefit. Some antimicrobials may be necessary as preservatives, but these merely protect the product from degradation and do not provide a health benefit. Products marketed as being “antimicrobial” or having a health benefit may contain additional antimicrobials beyond those needed for preservation, and these products have not been shown to provide any actual health benefit. Worse, the added antimicrobials can migrate out of the products and end up in the dust of interior spaces where people can become exposed. Of particular concern are antimicrobials based on silver nanoparticles (nano-silver). These ultra-small particles are not well understood, and are able to pass through the walls of cells in the body. Products described as “antimicrobial” or claiming to have a health benefit are best avoided whenever possible. For more information on Antimicrobials, read our blog post or the full report from HBN and Perkins + Will, Healthy Environments: Understanding Antimicrobial Ingredients in Building Materials.

Linoleum is a very good option for flooring to avoid toxic substances. Excluding the topcoat, it’s typically made from bio-based and non-hazardous ingredients, and is free of the problematic additives used in vinyl products. However, all floors on the market contain a topcoat which may contain substances of concern, and which manufacturers typically do not disclose. Since this is not unique to linoleum, it does not impact the rating - see the Read More section above for more information.

Pre-finished solid wood floors are a very good flooring option. Made from a single piece of wood, and purchased with a stain and topcoat already applied, this type of flooring allows for the chemically intensive finishing processes to take place in a factory where there are pollution controls and workers are protected.

If possible, find flooring that can be installed without an adhesive.

Engineered wood is a lesser option than solid wood because it requires the use of a binder and other adhesive ingredients; however, an engineered floor can still be a preferable option in terms of user exposures to these chemicals if it is purchased pre-finished.

Formaldehyde-based binders emit formaldehyde (a carcinogen and asthmagen) over time. Preferring floors made with an NAUF (no added urea formaldehyde) binder at a minimum is a good practice; an NAF (no added formaldehyde) binder is even better. See our Composite Woods Hazard Spectrum for a further ranking of composite wood binders.

When possible, prefer a product that does not require an adhesive for installation.

Ceramic tiles made without toxic glazes can be relatively low-impact materials for a flooring (or wall) installation. Tiles made in the USA are typically free of lead compounds in their glazes. Look for tile product literature that identifies where they’ve been made, and what they are made of, including frits, glazes, and pigments. Unglazed tiles are most preferred.

Avoid tiles with non-specific post-consumer recycled content. These contents may be old cathode ray tubes (CRTs) from TV sets and computer monitors. They contain high concentrations of lead. Tiles with CRT content are sometimes called CRT tiles.  

For more information, read Made in the USA: A Healthy Choice for Ceramic Tiles

As noted above, solid wood floors are a good flooring option, made from a single piece of wood without additional binder. When the boards are installed unfinished and require stains and topcoats to be applied within the building, those volatile and sometimes flammable chemicals can be brought into the project in an uncontrolled way, exposing installers and others nearby. Prefer pre-finished solid wood floors if possible, and look for flooring that can be installed without an adhesive.

Biobased flooring is a category of products using plastics or other materials derived from plants. These polymers are typically new and rely on proprietary technologies. Without disclosures about the nature of these polymers it is often difficult to assess their hazards. When considering a biobased flooring product, prefer those with a Health Product Declaration or other document providing transparency about the product’s content and associated health hazards.

Floors made from new rubber do not contain the highly toxic legacy contaminants often found in recycled rubber floors (see below).

However, the composition of these floors can vary widely, and manufacturers often do not disclose their contents. Further, isocyanates used in the binder that holds the rubber granules together are asthmagens.

Laminate floors are a type of engineered floor made by layering a sheet of decorative paper infused with a binder over a plank of composite wood. The pattern on the paper is usually intended to resemble the grain of a wood floor. Like other engineered floors, care should be taken to find products with a NAUF (no added urea formaldehyde) or NAF (no added formaldehyde) binder, and that do not require adhesives for installation. Note that unlike other engineered floors, laminates can not be sanded or refinished. Laminate flooring manufacturing has been plagued by supply chain quality control problems, as evidenced by issues like the Lumber Liquidators formaldehyde scandal in 2015.[4]

Carpeting is variable and can be made in many combinations of backings, face fibers, and surface treatments. Carpet with this ranking on the hazard spectrum does not contain the chemicals and chemical classes that are highest priority to avoid: fly ash, vinyl and polyurethane backings, and PFAS.

Vinyl and polyurethane backings have significant life cycle concerns and often contain hazardous additives. Alternative backings like polyolefin are less hazardous and more readily recyclable at the end of the product’s life.

Fly ash is commonly used as a filler in carpet backing and it contains heavy metal contaminants. Alternative fillers include calcium carbonate and ground, recycled post-consumer container glass which are becoming more common and don’t contain toxic substances.

Per- and polyfluoroalkyl substances (PFAS), commonly used in stain-repellant treatments for carpet fibers, are a high priority to avoid. Alternative treatments are becoming available and appear to be better from a health standpoint, but greater transparency about their chemical identities and hazards is still needed.

Because more transparency is needed about PFAS alternatives, and additional hazardous chemicals may be found in carpets meeting the requirements of this category, it is ranked as yellow instead of green. Additional chemicals of concern that may be found in carpet include antimicrobials and flame retardants.

For more information on carpet content and carpet recycling, see the brief on HomeFree or the full report here: Eliminating Toxics in Carpet: Lessons for the Future of Recycling.

As noted above, engineered floors are made by pressing layers of wood together with a binder into a solid board. When the boards are installed unfinished and require stains and topcoats to be applied within the building, those volatile and sometimes flammable chemicals can be brought into the project in an uncontrolled way, exposing installers and others nearby. 

Engineered floors requiring on-site finishing are not recommended. However, if this material must be used, preferring floors made with an NAUF binder (good), or NAF binder (better) can decrease exposures to formaldehyde formaldehyde (a carcinogen and asthmagen) after the installation is complete.

Note that some floors are typically sold unfinished, but can be pre-finished by the manufacturer if requested.

Because of the toxic processes required to make polyvinyl chloride (PVC), commonly known as vinyl, and the toxic pollution created when it is disposed of, vinyl floors of any kind are not a preferable material. However, in the instance where vinyl must be used, vinyl that has been reformulated to be free of hazardous phthalate plasticizers and doesn’t contain toxic or unnamed post-consumer recycled content should be preferred.

For more information on PVC see this joint publication between HBN and Perkins + Will.

While US manufacturers have eliminated toxic lead compounds from ceramic tile glazes, overseas manufacturers continue to use them. Eighty percent of tiles sold in the US are imported, mainly from Europe and Asia, where leaded glazing remains common.  Unless manufacturers specifically state otherwise, you should assume that glazed tiles not made in the USA contain lead (a PBT with cancer, developmental, and reproductive hazards). In addition, tiles with post-consumer recycled content from cathode ray tubes (CRTs), sometimes called CRT tiles, also contain lead from this recycled material.

When the location of manufacture can not be determined, the safest tile choices are unglazed tiles, or glazed tiles that are rated high for traffic abrasion (an abrasion resistance rating of IV or V according to ASTM C1027/ANSI A137.1, sometimes referred to as a PEI rating [5]). The glazes of these tiles are less likely to wear down over time and introduce any lead that might be present into the living space.

For more information, read Made in the USA: A Healthy Choice for Ceramic Tiles

Because of the toxic materials required to make vinyl, and the toxic pollution created when it is disposed of, vinyl floors of any kind are not a preferable material.

In addition, the inclusion of recycled vinyl in new products is a major pathway for the introduction of hazardous materials. Because vinyl products of all kinds are recycled together, hazardous lead, arsenic, PCBs, and phthalates can be found in post-consumer recycled vinyl.

For more information on the hazards of recycled vinyl, see this report by Healthy Building Network.

Vinyl floors, whether sheet, tile, or plank, made in the conventional way, are a poor choice for a flooring material. Hazardous phthalate plasticizers, and stabilizers based on organotins which are PBTs, all present hazards to occupants when they leach out of the floors and into the living space.

For more information on vinyl, see this joint publication between HBN and Perkins + Will.

Rubber sheet flooring made with crumb rubber is not a healthy option. Crumb rubber (also referred to as post-consumer recycled content in this type of product) is sourced from recycled tire scrap and can include significant additional hazards. When tested, lead, hydrocarbon processing oils, and other hazardous and undisclosed materials have been found in these floors.

For more information read this 2013 report by Healthy Building Network.

Carpeting is variable and can be made in many combinations of backings, face fibers, and surface treatments. Materials of concern in carpets include:

Coal fly ash used as filler in carpet backings. Fly ash is a waste product from the combustion of coal and can be contaminated with mercury (a PBT developmental and reproductive toxicant) and other metals present in the coal itself.

Per- and polyfluoroalkyl substances (PFAS) used as stain-repellant treatments. Health hazard information is not available for all the chemicals within this large group, but PFAS as a class have been identified as chemicals of concern because many have been found to be highly toxic, persist in the environment, and build up in body tissues.[6]

Vinyl and Polyurethane backings. Because of significant life cycle concerns, vinyl and polyurethane are not preferred materials. Polyurethane is based on isocyanate chemistry. Isocyanates are a leading cause of workplace asthma,[7] so present a concern during manufacturing, and residuals may be present in the final product. Vinyl and polyurethane backings also commonly contain PBT tin catalysts, and vinyl backings may be plasticized with hazardous phthalates.

Carpets containing all these substances of concern are rated as red on the hazard spectrum - those that avoid them all are rated yellow, see above.

For more information on carpet content and carpet recycling, see the brief on HomeFree or the full report here, Eliminating Toxics in Carpet: Lessons for the Future of Recycling.

The inclusion of recycled vinyl in new products is a major pathway for the introduction of hazardous materials. Because vinyl products of all kinds are recycled together, hazardous lead, arsenic, toxic PCBs, and elevated levels of plasticizers can be found in post-consumer recycled vinyl.

For more information on the hazards of post-consumer recycled vinyl, see this report by Healthy Building Network.

Endnotes
[1] Unless otherwise noted, product content and health hazard information is based on research done by Healthy Building Network for Common Product profiles, reports, and blogs. Links to the appropriate resources are provided.

[2] Polyurethanes are based on isocyanates, which are asthmagens, and epoxies rely on chemicals like Bisphenol A (BPA) which is a developmental and reproductive toxicant and endocrine disruptor.  See Common Products for Bamboo Flooring (engineered), Hardwood Flooring (prefinished), Heterogeneous Vinyl Resilient Sheet Flooring, Homogenous Rubber Sheet Flooring - Virgin Rubber, Luxury Vinyl Tile (LVT), and Linoleum Flooring and Tian, Dong, Jeffrey Ross, Susan Monroe, and Larry Leininger. Uvv curable coating compositions and method for coating flooring and other substrates with same, n.d. https://patents.google.com/patent/US20100276059A1/en.

[3] Lipiin Sung, Tinh Nguyen, Andrew Persily, Nanoparticle Released from Consumer Products: Flooring Nanocoatings and Interior Nanopaints  Final Report to U.S. Consumer Product Safety Commission. Interagency Agreement CPSC-I-12-007. NIST Technical Note 1835. National Institute of Standards and Technology, U.S. Department of Commerce, July 15, 2014.  See also: Tinh Nguyen, Lipiin Sung, Joannie Chin, Andrew Persily, Characterization of Airborne Nanoparticle Released from Consumer Products. Final Report to U.S. Consumer Product Safety Commission. Interagency Agreement CPSC-I-12-007. NIST Technical Note 1787.  National Institute of Standards and Technology, U.S. Department of Commerce, August 2013.

[4] Cooper, Anderson. “Lumber Liquidators Linked to Health and Safety Violations.” 60 Minutes, March 1, 2015. https://www.cbsnews.com/news/lumber-liquidators-linked-to-health-and-safety-violations/.

[5] Tiles rated with an abrasion resistance rating of Class IV are appropriate for all residential and most commercial applications. Those with a rating of Class V are appropriate for all residential and commercial applications. “Understanding Ceramic Tile Technical Specification Charts.” Conestoga Tile, January 12, 2015. http://www.conestogatile.com/learning-center/understanding-ceramic-tile-technical-specification-charts/. and Simpson, Katelyn. “Tile Abrasion: ASTM C1027  and Possible Upcoming Changes.” TILE Magazine, October 2009. https://www.tcnatile.com/images/pdfs/Tile%20Abrasion%20-%20ASTM%20C1027%20and%20Possible%20Upcoming%20Changes.pdf.

[6] For more information on PFAS, see the U.S. Environmental Protection Agency (EPA) website here: https://www.epa.gov/pfas/basic-information-pfas and California’s Department of Toxic Substances Control draft report on PFAS in carpet here: http://dtsc.ca.gov/SCP/upload/Product-Chemical-Profile-PFAS-Carpets-and-Rugs.PDF.

[7] “Health Concerns about Spray Polyurethane Foam.” Overviews and Factsheets, US EPA, OCSPP, https://www.epa.gov/saferchoice/health-concerns-about-spray-polyurethane-foam.

 

Last updated: June 04, 2018

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