Harmful Emissions from Paint and Safer Alternatives
Milk paints and whitewashes
Paints are a major source of indoor air pollution. The US Environmental Protection Agency (EPA)puts paint on its top-five list of environmental hazards. The main hazard from paints is from volatile organic compounds (VOCs), which include chemicals such as benzene, formaldehyde, toluene, and xylene. Some of these chemicals have been shown to cause cancer or nervous system problems. Paint manufactured before 1978 may also contain lead, which can cause many health problems. Paint manufactured before 1950 contained as much as 50 percent lead. Paint solvents are of particular concern to people with heart conditions and those who wear contact lenses because methanol and certain other compounds can stress the heart. In addition, contact lenses absorb strong vapors and hold them against the eyes, causing irritation or eye damage.
The EPA has shown that when new paint is drying, indoor VOC levels can be 1,000 times the outdoor levels of VOC. For example, Southern California's South Coast Air Quality Management District estimates that paint emissions from homes and other structures in their region give off about 60 tons per day of VOC vapors in their region while gas stations and oil refineries give off about 44 tons per day.1 The reasons why paints give off so many vapors is because of the VOCs which evaporate into the air easily and because of the large surface areas typically covered by paint. Since many paints are toxic, California requires that conventional paints be disposed of as toxic waste.
Because paints are usually applied in occupied spaces, people are more likely to be exposed to the vapors from freshly painted surfaces. The VOC emissions from paints can continue even six months after application. The main sources for these VOCs are gloss paint and wood stain varnishes in newly constructed homes.2 The largest emissions of VOCs come mainly from the solvents in paints.
The best way to reduce one's exposure is to choose low-VOC paint. Conventional oil-based paints contain about 50% petrochemicals by weight. VOCs are found in these paints at 420 to 450 parts per gallon. By contrast, most water-based or latex paints contain about 5-15% petrochemicals, but they still may contain harmful solvents. In order to be considered a low-VOC paint, the VOC levels have to be less than 100 parts per gallon. Low-VOC interior wall paints are generally limited to flat, eggshell, and semi-gloss finishes in whites and soft pastels. Brighter, shinier colors require the use of petrochemicals that give off VOCs.
Low VOC on a paint label also means that the manufacturer has not exceeded a certain level of cancer-causing chemicals as listed under California law that is stricter than federal law.3 Beware of "no-VOC" marketing claims, since all paints will contain VOCs to some extent. For example, in an experiment conducted by the EPA of four paints that were promoted by the manufacturer as being "no solvent" and "VOC free," they found levels of formaldehyde in two of the four cans. The source of most of the formaldehyde turned out to be a biocide added to prevent the growth of mold. It is not known where the rest of the formaldehyde came from. Just because a paint says it is "no VOC does not mean it does not give off hazardous vapors!4
Latex paints are also available in low-biocide varieties which means they are 90 percent to 95 percent free of the preservatives and fungicides often added to water-based paints to fend off mildew and mold. Oil paints do not need biocides added to them since they are naturally toxic to mold and mildew.
All Natural Paints
There are all-natural paints available which do not contain any petrochemical products, but they may contain naturally occurring VOCs such as citrus-based solvent d, l-limonene, turpentine, tung oil, or pine resins.3 These natural VOCs can also cause reactions such as watery eyes or respiratory problems in people sensitive to these chemicals. Most natural paints are made in Germany using solvents from citrus and other plant oils. They also contain plant resins, finely ground minerals, and earth pigments. These paints may cost more, take longer to dry, and may require more coats than latex paint, but they are not as toxic. Too often cost alone is allowed to dictate the paints, varnishes, and other finishes with no thought given to the fact that high VOC-content products can release dangerous vapors which may be more costly in the long run.
Milk Paints and Whitewashes
The least toxic of all paints are milk paints and whitewashes. Milk paints are made with milk proteins, earth pigments, lime, and clay. These paints are free of solvents. However, areas painted with these paints may need to be painted more often. Whitewashes contain lime paste, water, and salt. They are best used on plaster, cement, or stucco walls.
Odor-free finishes. Better Homes and Gardens. April 1997:58.
Yu C, Crump D. A review of the emission of VOCs from polymeric materials used in buildings. Building and Environment. 1998;33(6):357-374.
The right paint. Mother Earth News. June/July 1999:80-1.
U.S. Environmental Protection Agency. Evaluation of low-VOC latex paints. Inside IAQ: EPA's Indoor Air Quality Research Update. EPA/600/N-98/003. Fall/Winter, 1998.