Recent complementary studies of paint ingredients reveal some of the contrasting health and environmental implications of acrylic and mineral binding agents. Separate research teams led by the Danish Technological Institute and the architectural firm, Henning Larsen, explored the chemical content and climate impact of the same 30 paint products commonly used on interior walls and wood/metal trim, and concluded that few could be characterized as benign.
Both studies were released in late August 2024. The team investigating chemical content identifies an array of concerning preservatives, perfluoroalkyl and polyfluoroalkyl substances (PFAS) and volatile organic compounds (VOCs), which are dispersed into indoor environments at differing intensities depending on the paint’s binding agent. The team investigating climate impact advises that mineral-based paints are generally preferable to those with plastic, but cautions that consumers are an uncontrolled variable since much depends on the number of coats they choose to apply.
Analysis of the paints’ chemical content involved researchers from the Danish Technological Institute, the Danish Consumer Council, Denmark’s Aalborg University and Henning Larsen, and focused on 30 products that are commonly available in the Danish market. These included both natural and industrially manufactured formulas and some products participating in certification or labelling schemes such Nordic Swan Ecolabel and Danish Indoor Climate Labelling.
Chemicals were measured within liquid and solid paint and from paint emissions. In addition to the binding agents, hazardous elements can lurk in other paint ingredients, including pigments, solvents and various additives such as surfactants, driers, plasticizers and preservatives. (Notably, lead is a preservative.)
More than half of the tested samples contained the preservative, benzothiazolinone (BIT), with the highest detected concentration at 360 milligrams per kilogram (mg/kg). Half the samples contained methylisothiazolinone (MIT) at levels of less than 5 mg/kg and more than one third (11) contained low concentrations of formaldehyde.
Two-thirds of the samples contained ammonia, which exceeded 400 micrograms per cubic metre in eight cases. As well, researchers found heavy metals such as lead, chromium and zinc in some samples.
Three tests for emissions detected 139 different chemical compounds in the air of newly painted rooms. Acrylic paints contributed the greatest quantity and highest concentration of those contaminants — which the research report partly attributes to their disproportionate share (73 per cent) of the sample size — but for a shorter duration.
“VOC levels generally peaked on painting days, especially for acrylic paints, and generally declined to near-background levels within three days,” it states. “In contrast, paint containing linseed oil exhibited a slower reduction, taking 14 to 30 days to reach background levels.”
Researchers from Henning Larsen calculated the climate impact of the 30 paints based on their ingredients, the formulation density, surface coverage achievable from a specified quantity and the manufacturer’s recommended number of coatings. This was cross-tabulated with data from the German government’s ÖKOBAUDAT environmental evaluation platform for construction products to derive a metric for kilograms of carbon dioxide equivalent per square metre (kgCO2e/m2) of finished painted surface.
On average, CO2e output from mineral-based paints is found to be about 44 per cent lower than emissions from acrylic paints. This is attributed to the binding agents and to performance aspects of the formulations since fewer coatings are typically required with mineral-based paints, which use lime, clay or silicate as the binding agent.
“The amount used has a significant influence on the degree to which the paint impacts the climate,” the report states. “The number of treatment layers applied is influenced by both the substrate and the consumer’s satisfaction.”
Both studies decry the general lack of product-specific information available in the marketplace and/or inconsistent data that makes the environmental product declarations (EPDs) that do exist difficult to compare. When it comes to monitoring for chemical content, researchers stress that specifiers, purchasers and contractors should have the ability to easily determine product profiles and the risks associated with different types of paint, and be aware of additional conditions that can heighten or lower those risks.
“It is crucial to emphasize increased ventilation during and after painting to minimize exposure,” the chemical content study states. “Environmental implications include the risk of soil and water contamination from improper disposal of paints containing harmful metals. This underscores the need for sustainable paint manufacturing and proper disposal practices within the paint industry.”
Meanwhile, researchers exploring paint’s climate impact muse on more abstract concepts.
“In certain applications interior paint fulfills a functionality and in many other applications paint fulfills a purely aesthetic need,” they submit. “A desire for a full-covering, homogeneously painted wall has greater environmental consequences. Perhaps our aesthetic understanding of what constitutes a beautiful wall is outdated?”
