Why’s That on the Red List?

Several groups publish “red lists” of chemicals and materials of concern in building products. Most of the substances on these lists are there for obvious reasons: they are common and may contribute to global warming, increase cancer risk, or bioaccumulate in ecosystems. Other red-listed chemicals and materials, however, cause a certain amount of head-scratching among some of us because we didn’t think of them as very toxic.

Copper is on the Perkins+Will Precautionary List for exterior applications only. Runoff from copper flashing or decorative finishes may be toxic to aquatic species. Acid rain accelerates copper corrosion, increasing the potential for toxic runoff.

Boric acid is a natural flame retardant and biocide found in cellulose and cotton insulation and used for pest management and cleaning. This chemical was recently added to the European Union’s REACH Candidate List due to evidence of reproductive toxicity in humans. Toxic levels are 10 mg/day for adults and 3 mg/day for toddlers—far above what most people are likely to ingest in day-to-day life. However, the potential toxicity of boric acid is one more reason for cellulose insulation installers and other exposed workers to wear protective gear.

Polyurethane foam, used for building insulation and air sealing and found in furniture and appliances, appears on the Perkins+Will Precautionary List and is proscribed in some forms by Passive House Institute U.S. In both cases, the foam itself is not the primary issue but rather the high greenhouse gas emissions caused by common polyurethane blowing agents (see “Avoiding the Global Warming Impact of Insulation,” EBN June 2010). Foam products should be scrutinized for their global warming potential as well as toxic flame retardants.

Neoprene, the trade name for polychloroprene, is a synthetic rubber used to make gaskets, weatherstripping, and other sealing products. (Outside the building industry, you’ll find it in wet suits, thermal mug holders, and waders). Polychloroprene is a red-listed chlorinated plastic in the Living Building Challenge and on the Perkins+Will Precautionary List. It is not known to break down or offgas during use and usually appears in very small quantities in buildings; but chloroprene, the liquid from which polychloroprene is manufactured, is a known carcinogen and may also be a source of persistent, bioaccumulative toxic chemicals (PBTs). Some manufacturers have replaced polychloroprene with less-suspect synthetic rubbers. Santoprene, for example, a proprietary blend of EPDM and polypropylene, performs similarly and does not raise the same concerns.

All these materials made it onto someone’s red list for a good reason. When specifying products, though, most designers focus on lower-hanging fruit first: more hazardous and more widespread chemicals like volatile organic compounds, heavy metals, and PBTs.

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IMAGE CREDITS:
1. Illustration: Peter Harris

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