Hexabromocyclododecane, commonly known as HBCD, is a flame retardant that is starting to give a lot of green builders headaches.
Many people have never heard of this chemical compound, used in polystyrene insulation, but it could be in your house. Indeed, you are likely to be carrying some in your body.
This flame retardant has been found in human breast milk, body fat and blood. In the United States, “everyone has it in their tissues. In Europe, where HBCD is more widely used, the exposure is higher,” said biochemist Arlene Blum, executive director of the Green Science Policy Institute and an expert on brominated and chlorinated flame retardants.
Not only is HBCD found in human tissues, but it’s also found in wildlife and aquatic organisms all over the globe. In the United States, HBCD is carried through rivers and streams to the coasts, where it comes to rest in ocean sediments and enters the food chain. The highest levels of HBCD recorded to date were found in sea lions that were feeding on clams, shrimp and other bivalves off California, Blum said.
The Environmental Protection Agency and the European Chemicals Agency have said HBCD persists in the environment and does not break down into safer chemicals. It is toxic to aquatic invertebrates. According to EPA’s HBCD Action Plan, released in 2010, “It also presents potential human health concerns based on animal test results indicating potential reproductive, developmental and neurological effects.”
The European Union announced in February that HBCD is one of six substances of “very high concern” that “will be banned within the next three to five years unless an authorization has been granted to individual companies for their use.” These substances “cannot be placed on the market or used unless authorization has been granted for a specific use.”
How has HBCD become so widespread? Environmentalists have said the most likely primary source is emissions that escape during its manufacture or after it is applied as a flame retardant. Because HBCD is not chemically bound to the material it protects, it will eventually escape into the air, said Alex Madonik, a chemist with the Green Science Policy Institute.
But, Madonik said, in 2008, when the European Chemicals Agency determined that HBCD was a “substance of very high concern,” it also concluded that when HBCD is used in insulation, its predicted exposure is low. For this reason, European polystyrene insulation manufacturers might request authorization to continue using HBCD. But even if this is granted, Madonik said, “they will be strongly encouraged to develop alternatives.”
What is EPA’s position on HBCD? Despite efforts to get precise information from its Office of Pollution Prevention and Toxics, I did not get answers. But EPA’s Action Plan states that it is “considering initiating rulemaking” that “could take the form of a comprehensive ban” or “a more targeted regulation to address specific activities.” EPA “intends to publish a notice of proposed rulemaking by the end of 2011,” it said.
All this raises an obvious question for American homeowners and green home-builders: Is it okay to use materials containing substances that raise havoc with the environment and increase the chemical burden in everyone?
There are no easy answers.
Polystyrene insulation is favored by green-home builders because it creates an extremely energy-efficient building envelope. Reducing home energy use is a cornerstone of green building because it helps to cut greenhouse gas emissions. Home energy use accounts for about 20 percent of the greenhouse gases emitted by the United States every year.
From a fire-safety perspective, a flame retardant for polystyrene is necessary. Without it, applying an open flame to this material is like throwing a lighted match at solid diesel fuel, said Alex Morgan, a safety materials scientist at the Research Institute at the University of Dayton. When a retardant such as HBCD is added to polystyrene, the material melts away from an approaching flame. HBCD does not prevent fire; it retards its speed, giving building occupants a brief window of time to escape, Morgan said.
Morgan also said the environmental impacts of building materials as they are manufactured and as they burn are not considered in U.S. fire and building codes. But, he added, that is beginning to change as awareness of such issues increases.
The companies that manufacture the two types of polystyrene insulation used in the United States, expanded polystyrene (EPS) and extruded polystyrene (XPS), are developing alternative flame retardants, but they have declined to give specifics. Andrew Bayley, a board member of the Expanded Polystyrene Molders Association, said in an e-mail that identifying a viable alternative to HBCD and taking it through fire safety materials testing and code approval processes could take five to 10 years.
In the meantime, what are the alternatives? Blown-in cellulose is widely available, affordable and environmentally benign. It is made with recycled newspapers, and the flame retardant is boric acid, a naturally occurring substance that does not introduce new pollutants into the environment, Madonik said. But blown-in cellulose is not as energy efficient as polystyrene, he said. For it to achieve the same level of efficiency, a wall would have to be thicker.
HBCD is only one example of a much bigger issue: Every day, thousands of chemicals are dispersed into our environment. Contrary to what many people think, the EPA does not have the authority to demand routine testing before any of them are marketed. It can only demand pre-market testing or regulate production when it has compelling evidence that it is needed — as the agency is considering with HBCD.
While dangerous chemicals do not lurk under every bush, John Wargo, a professor of environmental policy and risk analysis at Yale University, sums up the need for vigilance in the first sentence of his book “Green Intelligence.” There “has been a change in the chemistry of the human body. Each day most people are exposed to thousands of chemicals in mixtures that were never experienced by previous generations.”
Wargo says that in 1999, when the Centers for Disease Control and Prevention began testing the tissues of Americans for environmental contaminants, it found that “most individuals carry in their bodies a mixture of metals, pesticides, solvents, fire retardants, waterproofing agents and by-products of fuel combustion.”
Katherine Salant has an architecture degree from Harvard. A native Washingtonian, she grew up in Fairfax County and lives in Michigan.