Over the past dozen years or so, as LEED, Living Building Challenge, and other rating systems for healthy buildings have become mainstream and influenced the vocabulary we use to make product choices for our buildings. Part of this vocabulary is the red list, referring to lists of chemicals to eliminate from usage. “Red list” is an evocative image, right? Stop! Don’t come close!
I am willing to stipulate that chemicals on the “red lists” have known health impacts. It is true that listed chemicals are known to be carcinogenic, mutagenic (cause mutations in DNA), or neurotoxic. Others are implicated with birth defects. Groups like Clean Production Action, creator of Greenscreen, have created systems to generate reports on chemicals based on their hazard profile, using government or other dependable research sources on those chemicals. Greenscreen is an “open source and transparent chemical hazard assessment tool” and is available for consumers or professionals, and generates user-friendly graphical reports like this one:
where once you understand the abbreviations, you easily see how hazardous your chemical is.
The assumption here is that chemicals that are hazardous are necessarily bad. Triclosan (as shown above) has very high acute toxicity to humans among other “High concern” items, but it has a variety of consumer applications that actually make use of that toxicity, like as an antibacterial agent in toothpaste that helps prevent gingivitis. That might be a modest benefit, but it’s an example of how a chemical that may have a harmful profile can be beneficial (or at least harmless) at specific doses.
So hazard identification is only the first step. Far more useful is to evaluate risk. Risk assessments of a chemical take into account both the hazard, the dose-response and exposure characteristics. The EPA published guidelines in their Human Health Risk Assessment guidelines and made them available on their website.
In addition to dose-response, other factors include reversibility of adverse effects (do they wear off with time), probability of incidence (not every person will feel the same effects from an exposure, and can vary with age, race, etc).
The “trick” – and it’s not really a trick, it requires the work of understanding the chemistry – is to recognize the hazards but limit the risk by knowing how much exposure to the chemical is required before some harm sets in. The US National Science Foundation, working with the American Chemical Society Green Chemistry Institute has published a standard method to more thoroughly evaluate and score chemicals on a risk basis.
That standard, ANSI 355-2011 provides a more rational way to determine when chemicals should be eliminated or limited. The Greenscreen method stops at the right-hand column, while the NSF method follows the chemical through its life cycle and use.
Risk-based assessments are not yet standard in the industry, and architects and specifiers, who are not chemists, are being told to rely on Health Product Declarations prepared by product manufacturers under the guidelines of the HPD Collaborative (http://www.hpd-collaborative.org). This organization, right on its homepage, says they are the organization that “created, supports and evolves the Health Product Declaration (HPD), an open standard format for the accurate reporting of material contents and potential health hazards.” (emphasis added).
Potential health hazards are not even close to the whole picture, since health hazards can be ameliorated by controlling exposure. Specifiers and architects should be careful about putting decision-making weight in the information contained in HPDs or even in red lists. If they do, they may inadvertently reduce the quality of their buildings. Instead, until more risk-based product assessments are available, we should prioritize known criteria like performance and longevity.