Potential toxicity of materials used for home insulation.

The two aqueous solutions used for production of residential home insulation by the so-called urea-formaldehyde process were tested for their ability to react with cellular macromolecules. One of the components (the catalyst-surfactant) changed the apparent molecular weight of isolated DNA and increased its rate of attachment to bacterial and animal cells. The other component (the formaldehyde-urea resin) showed both these activities, especially following its exposure to mouse or rat liver extracts (postmitochondrial supernatants). Actively growing HeLa cells exposed to the catalyst-surfactant solution and then extracted with phenol yielded diminishing amounts of DNA, suggesting the formation of strong bonds to other cellular macromolecules, most likely to proteins. Formation of complexes between nucleic acids and proteins, enhanced cellular binding of DNA, and decreased extractability of DNA from growing cells exposed to chemicals have been found in separate studies to correlate with carcinogenic activity of various substances. Since a significant number of buildings will be insulated with this urea-formaldehyde foam and since such foam is also used in agriculture on crops, appropriate precautions should be taken to limit human exposure to the component materials.