Psychologists have long known that the colors with which we surround ourselves can affect our energy and our moods. Unfortunately, too few professionals of any type realize how the medium we use to create those colors can affect our health and the health of the planet. This article looks at new developments with interior paints and explores the benefits of these developments for indoor environmental quality, resource use, and pollution prevention.
As might be expected in our ever-growing economy, the scale of the paints and coatings industry is huge.
Roughly 1.2 billion gallons (4.5 billion l) of coatings were sold in the U.S. in 1996, with a value of $16 billion, according a report from the National Paint and Coatings Association (NPCA). Just over 50% of this market (by volume) is categorized as “architectural coatings,” which include paints, stains, clear sealers—anything applied to buildings or building components in the field, as opposed to factory-applied finishes. About 57% of the architectural coatings, or 365 million gallons (1.4 million l), were sold for interior use. While there are still many small paint manufacturers, the industry has been consolidating rapidly in recent years, so that the six largest makers now account for nearly 80% of the sales. These manufacturers, along with a handful of specialty, environmentally driven companies, are responding to rapid changes in regulations and market demand with an evolving array of products.
What’s in a Paint?
In the most general terms, paint consists of a pigment, which gives it hiding power and color; a binder, which creates the film that holds the pigment on the substrate; and a carrier, which keeps the binder and pigment in liquid form so it can be applied to a surface.
Oil-based paints traditionally use a drying oil, such as linseed, soy, or tung oil, as the binder. In modern paints these oils are modified into a synthetic polymer known as an alkyd. The alkyd resin is dissolved in a petroleum-based solvent, such as mineral spirits. Recent environmental regulations and health concerns have driven the industry toward high-solids alkyd binders that require less solvent, toward less-toxic solvents, and generally away from oil-based paints.
Driven primarily by regulations aimed at reducing smog, the architectural coatings industry has been gradually switching over to latex, or waterborne, paints. Latex paints have the same basic components as oil-based paints—pigment, binder, carrier—but their formulations tend to be more complicated because additional ingredients are needed to keep the solids in suspension (they are not dissolved in the carrier, as the binders are in solvent-borne paints), to keep the paint from foaming, and to achieve various other functions. Until recently, all latex paints have included some solvents—primarily as coalescing agents, which keep the binder soft and available to form a film as the solvent evaporates.
Latex paints also require in-can preservatives to protect them from spoiling. “Latex resins are like agar for bacteria; they just love it,” says Steve Sides, Director of Environmental Health and International Affairs Division at the National Paint and Coatings Association. In oil-based paints, the solvent serves as the preservative. Fungicides are also added to most exterior paints and some interior paints to reduce mildew growth on the cured paint in humid conditions, although mildew growth after application is more of a problem with oil-based paints than with latex. Preservatives and fungicides, collectively referred to as “biocides,” may include arsenic disulfide, phenol, copper, formaldehyde, quarternary ammonium compounds, and many others, according to the American Institute of Architect’s Environmental Resource Guide. “While biocide manufacturers claim that the formaldehyde in these products won’t come out, EPA data shows that this is not the case,” reports John Chang, a researcher with the EPA’s Indoor Air Division.
Although “latex” once referred only to a natural extract from certain plants, it is now used to describe any of a broad range of mostly synthetic resins that remain flexible over time. The binders used in latex paints are typically polyvinyl acetate (commonly known as white glue), acrylic resins, or a combination of the two. Pure acrylic paints are generally of higher quality and more expensive than vinyl-acrylics. (While the term “vinyl” is often used as shorthand for polyvinyl chloride, or PVC, in this case it refers only to polyvinyl acetate; PVC is used in some specialty industrial coatings, but rarely in architectural coatings.) Paint quality is also determined by the ratio of binders and pigments (solids) to the overall paint. Solids content can range from 25% to 45% by volume. This figure may appear on the technical data sheets for paints. If it doesn’t, solids content can be determined by comparing the wet film thickness to the dry film thickness. For example, dividing a wet film thickness of 4 mils (0.10 mm) into a dry film thickness of 1.5 mils (0.04 mm) yields 0.375, or 38% solids.
The primary pigment used in nearly all paints is titanium dioxide, which is derived from sands rich in titanium-containing minerals. Titanium dioxide provides the hiding power to cover whatever is under the paint surface, and a bright white color. Roughly one-quarter (by weight) of a typical can of paint consists of this mineral. Chalk, talc, and certain clays are also used as white pigments, though these are less effective than titanium dioxide.
The other primary inorganic (mineral) pigments used are iron oxides, which can be refined from iron ores or synthesized from other minerals. Most iron oxide pigments are made from ferrous sulfate, which is created during the processing of titanium dioxide, or from sodium hydroxide, which is a by-product of chlorine production from salt brine. The other large (and growing) class of pigments are organic pigments synthesized from petrochemicals. These tend to be more expensive than inorganics and they are more susceptible to fading over time, but they offer brighter colors and a wider range of color choices.
With oil-based paints, the entire carrier is a volatile organic compound (VOC), creating odors and contributing to smog generation as it evaporates.
Most latex paints contain some solvents, primarily coalescing agents, but since the carrier is water, the overall VOC levels are much lower, ranging from 0 to 200 grams per liter, compared with 250 to 750 g/l for traditional oil-based paints. VOCs are often referenced as the sole indicator for how “healthy” a paint is. At first glance this approach would seem to make sense, because chemicals that offgas (volatilize) are most likely to be inhaled and affect our health. A closer look, however, reveals that it’s dangerous to rely too heavily on this one indicator.
There are two reasons to avoid (or minimize) VOCs in paints: ambient air quality and indoor air quality. From a regional and global environmental perspective, VOCs react in sunlight with other pollutants, such as nitrous oxides from combustion of fossil fuels, to create ozone and smog. Unlike ozone in the stratosphere, which protects us from overexposure to ultraviolet radiation, ground-level ozone is a pollutant that causes respiratory problems, damages plants, and contributes to global warming.
The need to reduce ground-level ozone is the primary motivation behind regional, state, and now national regulations that limit the amounts of VOCs in coatings (see Table 1). In preparation for establishing a national standard, EPA determined that architectural coatings account for “about 9 percent of the [VOC] emissions from all consumer and commercial products,” according to the U.S. Federal Register of September 11, 1998. The new standard affects coatings manufactured after September 13, 1999, except for coatings registered as pesticides, which have until March 10, 2000 to comply. Long before this national regulation appeared, some regions of the country with serious smog problems have been driving the industry toward lower VOC levels. For example, the new national limit of 250 g/l in flat paints has long been the law in southern California, and the limit there is scheduled to drop to 100 g/l in 2001 and to 50 g/l in 2008.
Advocates of indoor environmental quality buildings are also concerned about VOCs, but since there is little direct sunlight in buildings, ozone is not the main issue. More problematic are the potential health affects of the VOCs themselves and of various compounds that are created as these VOCs react with other chemicals in the coating and in the air.
Technically, a VOC is any organic (carbon-based) compound that evaporates at typical ambient temperatures. The European Commission defines VOCs as organic compounds with a boiling at or below 250°C (482°F). Some other definitions, such as that of the World Health Organization, exclude highly volatile compounds such as formaldehyde because they are already fully converted to gas form at ambient temperature and pressure.
The US EPA defines VOCs in an entirely different way. Since the regulation is concerned only with smog reduction, the EPA definition includes nearly any carbon-based compound regardless of boiling point, but then exempts compounds that do not react in sunlight (photochemically) to produce smog. The list of exempt chemicals is under continuous review and is updated periodically. These exempt chemicals may be included in paints and other products without contributing to the EPA-defined VOC content. While they may not contribute to smog, these chemicals are not necessarily safe to breathe, so from an indoor environment perspective they may still be of concern. Exempt VOCs that might be found in paints include acetone and methyl acetate.
There are other problems with relying on total VOC levels in a product as a toxicity indicator. VOCs come from a range of natural and synthetic sources, and those from either source can vary widely in their health effects. Many solvents traditionally used in paints are now being phased out due to their toxicity and potential carcinogenicity. The EPA maintains a list of hazardous air pollutants (HAPs) with stringent reporting requirements, and voluntary standards organizations like Green Seal have a list of chemicals that are not allowed in their eco-labeled paints.
To further complicate matters, VOCs in the air are never just one isolated compound, and even when information is available about the individual chemicals, their effect in combination can be quite different. In addition, VOCs can react with other chemicals to create new compounds not found in the original product. Recent research by John Chang of the EPA shows that irritating aldehydes are created during the curing of some alkyd (oil-based) paints—these aldehydes don’t appear in the uncured paint and don’t show up in the emissions data until about an hour after application. Previous research had shown examples of chemicals that react in the air with ozone and other compounds to form new chemicals, which may or may not be more problematic than the original compounds (see EBN
Paint chemistry is constantly evolving, and one recent breakthrough has been the emergence of latex paints made with no organic solvents.
Early generations of solvent-free latex paints suffered from various weaknesses. The first to be widely available, Glidden’s Spred 2000 (see EBN Vol. 3, No. 1, page 7) didn’t hold up well to scrubbing. But as the technologies have continued to evolve, so has the performance of these paints. Spred 2000 has been replaced in the Glidden (now part of ICI) lineup by the more durable Promaster paints, and at least a dozen other companies now offer solvent-free paints as “low-odor,” “zero-VOC,” or “very low-VOC” (see Table 2 on pages 14–15).
It is virtually impossible for a paint to eliminate VOC emissions entirely, as nearly every organic chemical is released in trace amounts as a gas. But the standard testing protocol for VOCs, known as EPA Reference Test Method 24, is not accurate at low levels, so any paint with VOCs in the range of 5 g/l or less can be called “zero-VOC.” Only one paint, ICI’s Lifemaster 2000, is independently certified as VOC-free by Scientific Certification Systems, Inc. of Oakland. SCS has the paint tested twice a year using a more sophisticated mass spectrometry method. ICI’s Robin Pirie contends that other paints are not as low in VOCs as theirs: “Other paints might not be zero-VOC if they were tested under this method.”
Most of these paints still use colorants with some solvent, so tinting the paint will introduce a small amount of solvent (proportional to the amount of color added). Since heavy tinting of these paints would introduce substantial amounts of VOCs, most of these are only available in light colors. The Lifemaster 2000 line is an exception, as is the Enviro-Safe line from Chem-Safe Products. These products and a few others use a somewhat more expensive solvent-free colorant system.
The large paint companies, including ICI, Benjamin Moore, and Sherwin-Williams, market their low-odor paints primarily to healthcare facilities and to building managers for use in occupied buildings. There are often substantial savings to be had in not needing to vacate a space when it’s being painted, and in allowing painters to work during normal business hours rather than paying extra for after-hours labor.
Benjamin Moore had originally introduced its Pristine zero-VOC line as a consumer product (see EBN Vol. 4, No. 1) but is now redirecting its marketing efforts at professionals and renaming the paint “Pristine Eco-Spec.”
“It was disappointing that consumers did not embrace Pristine initially,” says marketing director Eileen McComb. McComb feels that consumers are confused about the benefits of zero-VOC paints, since all latex paints are pitched as “low-VOC.” She’s optimistic about the professional market, however. “We were getting five or six calls a week. Many people are asking for clean-air formula product,” she notes. McComb attributes this interest among professionals to educational efforts from organizations such as the National Association of Home Builders, the U.S. Green Building Council, and the American Institute of Architects. Pristine Eco-Spec should be on dealer shelves in March of 1999.
“Zero-VOC” does not always mean “nontoxic” however, as some of the other chemicals used in these paints may be just as hazardous as those in standard paints. With the exception of a couple of products sold directly to users as low-biocide, all these paints contain toxic preservatives to give them the shelf-life they require in a typical distribution system. David Kibbey, a Berkeley, California consultant who works with chemically sensitive clients, reports that some of his clients are sensitive to certain zero-VOC paints, and other clients to different formulas.
A number of specialty paint manufacturers market products that claim to be less toxic than standard paints. Some of these are petrochemical- based, but the chemicals are chosen for low-toxicity. Others—imported from Europe—are based primarily on binders and solvents that are derived from plants rather than from petrochemicals. And a few, such as milk paint, avoid most of the toxicity problems altogether, but they also don’t form a protective film the way standard paints do.
Low-toxic paints made from petrochemicals tend to be relatively low in VOCs, though not necessarily solvent-free. San Diego-based American Formulating & Manufacturing (AFM) produces both zero-VOC and standard “low-VOC” water-based paints in its Safe Coat paint lines. Aside from low-VOC levels, AFM’s claims of low-toxicity are based on the use of safer ingredients. These include coalescing agents such as propylene glycol, instead of the more hazardous (and less expensive) ethylene glycol, and high-quality binder resins that cure into a tight matrix, making them less likely to release trace amount of hazardous chemicals.
Samuel Goldberg, president of AFM, claims that with their high-quality ingredients the paint performs as well as conventional paints, but he also acknowledges that there are compromises. “Our paint doesn’t do the painter’s job for them,” Goldberg notes, referring to the fact that standard formulations, with solvents, can make up for a lot of sloppy work. For example, AFM avoids phenol-based biocides, so the paints are less effective at preventing mildew spread, especially if surfaces are already contaminated. Proper surface preparation, always a good practice for a durable finish, is essential with these alternative products.
Anecdotal evidence on the performance of these products suggests that their performance has improved with recent reformulations, and they now perform similarly to conventional paint. Cost remains an issue, however, as they frequently run upwards of $30 per gallon. And none of these companies have distributors throughout the country (see table on pages 14-15); in an area with no local dealer, shipping costs and delays can also be obstacles.
Natural paints, represented in the U.S. by German imports Livos, Auro, and Bioshield, try to avoid petrochemicals entirely, making paints only from plant-based resins, solvents, and pigments. Auro paints claim to adhere to this rule strictly. Ingredients in Auro paints include dammer resin, carnauba wax, shellac, and natural latex. Calcium carbonate (chalk) is used as the primary hiding pigment. Livos and Bioshield use many of the same ingredients, though some Livos products contain isoaliphatic hydrocarbons, which are fossil-fuel solvents that have been purified to eliminate their more noxious properties.
These companies, along with the Old Fashioned Milk Paint Company in Massachusetts, also produce paints based on milk protein, or casein as the binder.
The Wisconsin Department of Agriculture has even researched the production of milk paint as a possible use for the roughly 20 million pounds (9.1 million kg) of milk that is dumped annually due to excessive antibiotic levels. (The antibiotics would first be removed using enzymes.) In addition to the casein binder, milk paint contains standard chalk and/or titanium dioxide pigments and lime. Some companies distribute milk paint in powder form, which avoids the need for in-can preservatives. Regardless of how it is distributed, milk paint must be protected from moisture both before and after application, or it can sour or mildew, and walls covered with sour paint are no small problem! A clear sealer is sometimes recommended to protect the milk-painted surfaces, but this negates most of the benefits of using this nontoxic finish.
Although it has only been a few generations since plant-based paints (typically with white lead—lead carbonate—as the pigment) were the only option, contractors and homeowners have now grown accustomed to the ease and convenience of petrochemical-based products. By comparison, most of the natural paints are quite sensitive to work with, demanding skill and experience. The results tend to be more of a handmade look than the industrial uniformity offered by conventional paints.
Other than milk paint, the fact that these paints are made from natural ingredients does not necessarily mean that they are nontoxic. For example, many natural paints rely on the citrus-peel extract d-Limonene as their solvent. This solvent has a strong, persistent smell, which some chemically sensitive people find problematic. “We painted our house with Livos paints, and my wife couldn’t move in for three months due to the strong citrus odor,” reports healthy house consultant John Bower. “Sensitive people tend to do better with the low-odor synthetic paints than with natural paints,” he told EBN. Toxicological data on d-Limonene confirms that it is a known irritant and sensitizer, even though it is “generally recognized as safe” for use in foods by the U.S. Food and Drug Administration.
Also, d-Limonene is one of the VOCs that is known to react with ozone in the air to form, among other things, formaldehyde.
Resources and Pollution from Manufacturing
There are so many different constituents in paints that assessing the life-cycle impacts of even a single paint formulation is a huge job. In general, petrochemical solvents are responsible for pollution problems from the wellhead to the end-use, and reducing their use is desirable. From that perspective alone, water-based paints are environmentally preferable. The environmental impact is further reduced by the fact that latex paints do not require solvents for cleanup. Due to the hazards involved, oil-based paints are rarely recycled into new paint. When they are collected for “recycling,” it is usually for use as fuel in cement kilns. Safety-Kleen, Inc. is the only company EBN found that is making new oil-based paint from old.
When it comes to binders, however, the situation is more complex because the alkyd binders used in oil-based paints are at least partially derived from plant-based resins, while the vinyl acetate and acrylic resins in water-based paints are produced via a series of highly toxic intermediaries in the petrochemical process.
Work is under way on a new generation of water-dispersible alkyds that perform like the high-quality binders in oil-based paints but are carried in water. Some of these are made using soy-based resins, which could help restore the market for plant-based polymers in the coatings industry. There is also a soy-based latex paint in the works that, according to the United Soybean Board, will be on the market later this year.
The production of pigments can be a highly polluting process. When titanium dioxide is extracted from sand, large quantities of by-products are produced that have historically been disposed of by ocean dumping and/or deep-well injection. The process of refining titanium dioxide is also very energy intensive, with significant releases of carbon dioxide and sulfur oxides. The European Community considers these problems associated with titanium dioxide so serious that they have established limits on the amount of white pigment allowed, and limits on allowable emissions from pigment manufacture, for paints under consideration for the European Eco Label.
A clear winner in terms of reduced upstream impacts is recycled paint, because the main raw material is leftover paint from other users. Recycled paint has a poor reputation, but there are, in fact, different degrees of recycling and qualities of paint, so some recycled paints might be appropriate for certain jobs. For the right application it makes sense to use recycled paint, not only to reduce environmental impacts, but also because it’s usually a bargain, with prices ranging from $0 to $10 per gallon.
The paint that is available free is the most risky and should be used only where a top-quality finish isn’t the goal. It is often made by local waste management agencies, which simply collect leftover paint, sort it by type and depth of color, and filter out the larger impurities. Giving this remixed paint away free is still a good deal for the agency, because otherwise they would have to pay to dispose of it. The biggest drawback with nearly all recycled paint is the limited color selection: typically off-white, beige, and brown.
True paint recycling involves getting the leftover paint to a paint manufacturer or specialized recycler, where it can be tested for various properties and so that virgin materials can be added, as needed, to create paint of the desired quality. This is the approach taken by the Atlantic County Utilities Authority, working with Focus Recycling in Warren, New Jersey, and by Paint Solutions, Inc., with operations in St. Louis, Missouri and Kent, Washington (with arrangements through Phillips Environmental for paint collection in ten western states). These recyclers sell primarily to state agencies and other large buyers, and they can custom-tint batches to meet specific orders.
The most sophisticated recycling is done by Kelly-Moore Paint Company at their Sacramento, California facility. Kelly-Moore has been selling recycled paint since 1992. Ray Julian of the company says that they remanufacture the paint to perform like their mid-grade virgin paint: “It’s a medium grade exterior paint,” he says, adding: “Our recycled paint is at least as good as most companies’ exterior acrylic latex.” Kelly-Moore’s E-Coat is the only recycled paint that is consistently available in smaller quantities. While it is not stocked at all Kelly-Moore stores, it can be ordered through them without any shipping charge.
Remanufactured paints (as opposed to locally remixed paints) are frequently tested for hazardous constituents and VOCs, and they are well within acceptable legal guidelines. Julian reports that the VOC levels in his paints typically run between 100 and 150 g/l, which is average for waterborne paints. Recycled paint lines don’t distinguish between interior and exterior use, and they are likely to contain small quantities of mildewcides from the collected exterior paints. Where indoor air quality is a paramount concern, recycled paints are not the best choice.
Dealing With Leftover Paint
Unfortunately, all too often leftover paint is dumped illegally into sewers or into the ground. The Province of British Columbia is far more aggressive about dealing with used paint than any other location in North America, requiring paint manufacturers to take back all leftover paint for recycling. To cover the cost of this mandate, all paint purchased in B.C. is assessed an “eco-fee” of Canadian $0.50 per gallon or $1 per five-gallon container. These fees are used by the B.C. Paint Care Association (established by the paint manufacturers) to support a network of over 100 collection sites in the Province, to which paint users can take their leftover paint. According to Paul Iverson, director of the Association, the eco-fees are the best educational tool for consumers, because they always want to know why they’re being assessed the fee. Their surveys indicate that before the program began in 1994, “42% of consumers knew not to put stuff down the drain or in the garbage,” says Iverson. “At the end of 1997, 87% of people knew.”
In the U.S., the NPCA purports to distribute information about paint recycling, but in effect the NPCA discourages the practice, either out of concern that it will make paint handling seem more cumbersome, or because its members might lose sales to recycled paint. With latex paint, the Association’s Web site actually recommends letting the paint dry and then discarding it with the trash, although it notes that this practice might not be legal in California, Minnesota, or Washington.
The good news is that regulatory constraints are actively removing the most polluting, oil-based paints from the market, while other bad actors, including lead and mercury, have already been eliminated. The bad news is that titanium dioxide pigment, used in nearly all paints, represents an often-overlooked environmental problem, and all conventional paints are products of a polluting and toxic petrochemical industry. Colors are a wonderful addition to our interior spaces, and they can contribute to the quality and mood of the space. Like most products, the best environmental solution is to use only what’s necessary and handle it with care.
The checklist on page 18 offers suggestions for reducing the downside of interior paints.
— Nadav Malin
For more information:
National Paint and Coatings Association
1500 Rhode Island Avenue NW
Washington, DC 20005-5597
202/462-6272, 202/462-8549 (fax) www.paint.org
Dana Duxbury, Paint Recycling Specialist
Waste Watch Center
16 Haverhill Street
Andover, MA 01810
508/470-3044, 508/470-3384 (fax) www.wastewatch.org
Deborah Stowitts, Communications Dept.
Southwest Research Institute
P.O. Drawer 28510
San Antonio, TX 78228-0510
210/522-2046, 210/522-3547 (fax)
1400 16th Street NW, Suite 300
Washington, DC 20036
202/588-8400, 202/588-8465 (fax) www.greenseal.org