Pollutants Boost Lead Paint Hazard

Two pollutants linked to transportation emissions react with surfaces coated with lead-based paint and increase release of lead pigments, a new study shows (Env. Sci. Tech., DOI: 10.1021/es901077m). The interaction may increase the risk of lead poisoning in children, particularly in urban environments and in the developing world.

Ordinary household dust can become contaminated with lead when leaded paint products deteriorate. But only a few studies have focused on the factors that facilitate the release of lead pigment granules from the paints. Now, environmental exposure scientist Rufus D. Edwards and colleagues at the University of California, Irvine, School of Medicine have examined the impact of nitrogen dioxide and ozone, two compounds associated with auto emissions, on surfaces containing lead paint.

“Typically, paint is composed of pigment granules and an unsaturated polymeric binder that holds them together,” Edwards says. “We know that O₃ and NO₂ react with unsaturated compounds. We were interested in whether this makes lead pigment granules more available to children’s hands,” he says.

The Irvine team applied a thin, uniform coating of lead paint to stainless steel surfaces. After exposing the surfaces to O₃ or NO₂, the researchers evaluated them by reflectometry and scanning electron microscopy. They also mechanically wiped each surface and measured the lead concentration on the wipe. Exposure to NO₂ and O₃ changed the surfaces’ morphology and significantly increased the amount of lead that can be wiped off them.

The study adds another factor to consider in risk assessment, not only in U.S. cities where lead paint remains a problem, but also in developing countries, many of which still sell lead paint and have booming urban centers that contribute to air pollution, Edwards says.

This study “highlights the importance of the often underappreciated science of heterogeneous chemistry in indoor environments,” says Richard Reiss, an environmental health scientist at Exponent, a consulting firm. “I suspect there are other connections between environmental contaminants that might be discovered with more study of indoor surface chemistry.”

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