This blog post, originally shared in the Pharos Signal, includes information about parts of Pharos that are no longer available. Please use it for historical reference and for the other useful information it contains.
This week Pharos opened its newest category of product evaluations: fluid applied flooring (FAF). This is a type of high performance coating used in areas where easy cleaning is essential. Fluid-applied flooring systems are most commonly applied to restrooms, janitor rooms, locker rooms, restaurants, day care centers, and laboratories. Usually these systems seal concrete, although they can also be applied to other substrates like wood, steel, and asphalt.
Many of these products are laden with asthmagens, carcinogens, endocrine disrupting chemicals, and/or other chemicals of concern. The most common systems are based on epoxy, isocyanate and/or acrylic chemistries.
Despite these hazardous ingredients, our research found scarce industry or government literature about potential risks from these chemicals to installers or building occupants. The only official guidance the Pharos team could find on avoiding hazards with fluid applied floorings came from the US Department of Health and Human Services. A design guide for the Head Start program warns that “this material should not be used without adequate time to off-gas."
Most building products are manufactured in a factory setting. Ideally, factories follow regulations and quality controls that prevent occupational exposures. The fluid applied flooring installation process moves these potential exposures onto building sites that can be far less controlled work environments.
Pharos has evaluated other site-applied products, like two-part epoxy and urethane adhesives, along with sprayed foam insulation. These products have come under increasing scrutiny for potential exposures to installers and building occupants. Fluid applied floors are large-scale variations of the same systems, but so far, have not been part of this discussion.
Data gaps are prevalent. We need to know: How long do these floorings take to cure, and how many toxic chemicals are being off-gassed?
* How long do these floorings take to cure?
Curing times for these products represent the time period during which exposures to hazardous volatile organic compounds (VOCs) from the product can be expected to be high. During this time, nobody should enter the space without proper safety equipment.
Curing rates, as reported by manufacturers, vary depending upon the base chemistry used in the flooring.
Methyl methacrylate (MMA) resins take the shortest amount of time to cure. Manufacturers report them to be “fully cured” in one hour or less. For example, BASF literature for one of its products states “within one hour of application, virtually 100% of the DEGADUR® binder system has been converted from a liquid to an inert solid. There are no unreacted portions of the material left to leach out of the system."
Epoxies and polyurethane resins may only take a few hours to cure, but a day or more may pass before the floor can withstand full traffic conditions. One epoxy coating manufacturer states that it may take 10-14 days to develop full chemical resistance.
Similarly, polished concrete flooring takes a day or more before full usage is recommended, but may take much longer to achieve full harness. One product data sheet reads, "The finished floor does not achieve its published surface hardness until after 28 days."
With some floors requiring many more days to develop their specified properties, chemical reactions clearly continue to take place even after consumer use begins. Chemical reactions could be leading to byproducts including possible VOC emissions. How long does this last and can VOC emissions continue to be a hazard over the long-term use of the floor?
As of now, the answers to these questions remain largely unaddressed by manufacturers and regulators.
* What and how much is being off-gassed?
Most manufacturers report their fluid applied flooring products have zero VOCs once cured, but the same floor products have resin components that are reacted on-site with manufacturer reported VOC content. BASF, for example, lists the VOC content of an MMA resin component as 198 grams per liter.
Assuming that the cured form is a high-boiling-point, non-volatile product, VOC emissions should go to zero after curing. However, key questions remain:
- How long do VOC emissions from the curing process continue? When does the product reach the zero VOC point?
- After curing, are there VOC emissions that escape reporting requirements?
If manufacturers performed VOC emission testing on products, we would know whether, by 14 days, these systems truly reach zero VOCs. We would also know how complete and how rapid the cure is. However, it appears that fluid applied floors have not gone through indoor air quality (IAQ) certification programs like Greenguard or California 01350 IAQ testing.
The answers to these questions are vital for installers and building occupants. Given the high levels of VOCs in components, we can assume that for some time during curing, there is a risk of exposure to chemicals of concern.
Even if tested and cleared for VOC emissions, hazards could be present in these products. Pharos researchers identified eleven ingredients of FAF components that are VOCs, but are not covered in current Greenguard or standard 01350 tests (1).
We also identified six VOCs used in fluid-applied floors that are addressed by VOC emissions testing programs. Note that these will only be flagged if they exceed levels considered by the emissions programs to be potentially unsafe. One of the chemicals - methyl methacrylate - is only evaluated by one of the programs (GreenGuard) and the level for flagging it is based on occupational safety assessments for healthy workers, not to protect babies and other vulnerable populations (2).
In addition, we identified six semi-volatile organic compounds (SVOCs) in FAF components (3). Current IAQ testing programs focus on VOCs and do not cover these chemicals. SVOCs, many of which are as hazardous as VOCs, can still migrate from the product.
While there is little information available that quantifies VOCs off-gassed during FAF installation, we can say what hazards are associated with the chemistries used in these products. Occupants can still be exposed to ingredients that do not off-gas and are supposedly bound up in the product. Building occupants may be exposed to these ingredients via direct contact or dust, which, through inhalation and accidental ingestion, can lead to respiratory or GI tract exposure.
Epoxy systems use significant amounts of Bisphenol A (BPA) and epichlorohydrin resins. BPA and epichlorohydrin are under increasing scrutiny for their developmental and reproductive, and carcinogenic effects, respectively. The Pharos research team has calculated that epoxy floorings contain upwards of 200 lbs of these resins per 1000 square feet. Epoxy resins and hardeners can also contain nonylphenol ethoxylates, SVOCs that are also persistent, bioaccumulative toxicants.
Polyurethane flooring systems contain isocyanates – some with 50 lbs or more per 1000 square feet – which, according to the EPA, are a leading cause of work-related asthma.
In the case of MMA flooring systems, manufacturer literature more openly discusses potential hazards. Product literature and safety bulletins report on MMA’s high flammability, reactivity, and distinct odor. They even note negative reports of carcinogenicity from exposure studies. However, these publications do not address MMA’s hazard as an asthmagen, which is of high concern to those exposed during installation. Over 500 pounds of MMA may be used per 1,000 square feet of flooring.
With health departments requiring the use of fluid applied floors in some building projects, and their use in schools and daycare facilities where children may be exposed, it seems imperative that more research and reporting be done to ensure the safety of workers installing the floor and future building occupants.
Further discussion about these and other issues in fluid applied flooring is available in our newly-published category description.
Sarah Lott is a researcher with the Healthy Building Network’s Pharos Project. Jim Vallette, Tom Lent, Melissa Coffin and Susan Sabella contributed to this article.
- The following VOCs are ingredients of fluid applied floors. They have boiling points under 250 deg. Celsius and are part of neither Greenguard nor standard 01350 IAQ tests: 2-(2-butoxyethoxy)ethanol (CAS No. 112-34-5); 2-Propenoic Acid, Polymer with Butyl 2-Propenoate and Ethenylbenzene (CAS No. 25586-20-3); Trimethylhexamethylenediamine (CAS No. 25620-58-0); Cresyl Glycidyl ether (mixed isomers) (CAS No. 26447-14-3); Solvent Naptha (CAS No. 64742-88-7); Aromatic naphtha (CAS No. 64742-95-6); Alky glycidyl ether (CAS No. 68609-97-2); Dicyclohexyl phthalate (CAS No. 84-61-7); N-methylpyrrolidone (CAS No. 872-50-4); Epoxy novolac (CAS No. 9003-36-5); and, Polymeric MDI (CAS No. 9016-87-9). Methyl methacrylate (CAS No. 80-62-6) is covered by Greenguard, but not standard 01350 testing.
- Greenguard thresholds for air concentrations of these VOCs, in parts per million (ppm) are approximately: 1,000 ppm (Propylene Glycol Monomethyl Ether [CAS No. 107-98-2]; Ethylbenzene [CAS No. 100-41-4]); 500 ppm (Methyl Methacrylate); 393 ppm (Ethylene Glycol, CAS No. 107-21-1); 200 ppm (Styrene, CAS No. 100-42-5); and 100 ppm (Acetic Acid, Glacial [CAS No. 64-19-7] and Vinyl Acetate [CAS No. 108-05-4]).
- SVOCs in FAF systems include Bisphenol A (CAS No. 80-05-7), 4-Nonylphenol (CAS No. 84852-15-3), and Methylene Bisphenyl Diisocyanate (pure MDI, CAS No. 101-68-8). Regarding pure MDI: the State of California Office of Environmental Health Hazard Assessment (OEHHA) has established a Chronic Reference Exposure Level for pure MDI. However, there is no Threshold Limit Value for pure MDI used as a Greenguard standard.