Water-Based Paints: Less Smelly, But Still Harmful?

Paint typically consists of four components: pigments, binders, additives, and a liquid that, if water-based, distinguishes it from solvent-based variants. Historically, solvent-based paints offered ease of application and durability, but they emitted volatile organic compounds (VOCs), contributing to odors and potential health problems. Water-based paints, often considered as environmentally friendly with low or zero VOCs. However, to achieve comparable performance and ensure product quality, they often contain various chemical additives including coalescing agents, wetting agents, preservatives, and high-boiling point solvents. Most of these are semivolatile organic compounds (SVOCs). Only a few studies have been conducted to investigate emerging chemicals in water-based paint products.

Ying Xu, Tsinghua University, Beijing, China, and The University of Texas at Austin, USA, and colleagues have found that some of them may contain VOCs and other potentially harmful substances. The team analyzed 40 water-based indoor paints from around the world, all among the top 70 best-selling brands, many of which claim to be zero or low-VOC. Most paint samples were white. They analyzed both dry and wet samples using gas chromatography/mass spectrometry (GC/MS) to determine their composition.

Twenty SVOCs were identified at concentrations ranging from 10 to 35,000 parts per million. While these are less likely to be in gaseous form, they can persist indoors for years, often incorporated into dust.

Endocrine-disrupting phthalates, which act as binders, were largely absent from the paints tested. However, several phthalate-replacement chemicals were detected. 2,2,4-Trimethyl-1,3-pentanediol diisobutyrate (TXIB), diisobutyl adipate (DIBA), and triethylene glycol bis (2-ethylhexanoate) (TEG-EH) were the main ones found in the current samples. Their toxicities are still being evaluated.

Nearly half of the samples analyzed contained measurable levels of isothiazolinones, preservatives that have been linked to skin irritation and asthma symptoms. In 24 of the wet paint samples advertised as either zero or low VOCs, eleven different VOCs, including ethylene glycol (EG) and 1,2-propylene glycol (PG), were detected at concentrations up to 20,000 parts per million.

These concentrations represent the chemical composition within the paint, not the air. The researchers say more research is needed to understand the extent of airborne emissions during drying. However, they conclude that given the potential exposure and risk, special attention needs to be paid to the chemicals used in “green” paint products. A case study of TEG-EH suggests that the use of water-based paints can lead to long-term exposure.