A Closer Look at Toxicity: Six Classes

A World of Chemicals

In today’s world, nearly all of our material needs and resources are in some way derived from industrial chemicals. They are in the furniture we lounge on, the doors we open, and the appliances, cookware, and clothing that we use every day. And the list goes on—the American Chemical Society estimates that chemicals are used in 96 percent of manufactured materials and products. This number has grown exponentially since the mid-20th century, especially in consumer products and building materials, and today the United States Environmental Protection Agency (EPA) estimates that there are over 80,000 chemicals in circulation in the US.

Many of the chemicals used in products make their way into our bodies and ecosystems. We are exposed to them constantly, so it is important to understand which are safe to use and which can cause harm to people, animals, and the environment. However, studying each of these 80,000+ chemicals is a significant infrastructural challenge, and as a result, most of them haven’t been adequately tested.

Challenges to Chemical Regulation

Knowledge Bank spoke with Arlene Blum, a biophysical chemist, mountaineer, and executive director of the Green Science Policy Institute (GSP), an organization whose goal is to facilitate safer use of chemicals to protect human and ecological health. According to Blum, some of the obstacles to phasing out harmful chemicals include the lack of government ability to regulate chemicals, supply chain complexity, and the current one-chemical-at-a-time regulation system. “Currently no government agency has sufficient authority to ensure the safety of chemicals used in everyday products. Even manufacturers may not know if the chemicals in their products are safe—confidential business information or CBI allows producers not to disclose the identity of chemicals. Another obstacle is that studying the tens of thousands of chemicals on the market today one at a time is not feasible. Phasing out a chemical can take years of research and advocacy.”

So, what can designers, manufacturers, and consumers do to avoid using harmful chemicals? Governments and organizations have published lists of specific chemicals that have been tested and are proven to be harmful, like the EPA’s Chemicals of Concern, the EU’s REACH Substances of Very High Concern, and the International Living Future Institute’s Red List. But Blum identified a crucial issue that escapes the purview of these lists: “The most likely replacement of a harmful chemical is another with similar structure, function, and potential for harm.” This can lead to a cycle of “regrettable substitutions” which undermine regulatory efforts and put people and the environment at risk. In the 1970s Blum brought national attention to the issue of dangerous flame retardants called polybrominated diphenyl ethers (PBDEs), found in children’s pajamas. The chemicals were quickly banned, but over thirty years later, she discovered that they had been replaced with organophosphate flame retardants in furniture, building insulation, and baby products. It turned out that the replacement was just as bad – if not worse than – the original.

An Innovative Framework for Identifying Toxicity

To address this issue, the Green Science Policy Institute developed Six Classes, a framework that identifies the most problematic categories of chemicals: PFAS; antimicrobials; flame retardants; bisphenols and phthalates; some solvents; and certain metals. Instead of focusing on individual chemicals, Six Classes defines these chemical groups according to their structure, use, or intrinsic hazardous properties. These groups are commonly used in consumer and building products, where many of them leach out into air and dust and end up in human bodies and the environment. The Six Classes approach is practical—Blum agrees that all chemicals should be tested for acute and long-term health effects before entering the market, but until this is possible it’s important to focus on avoiding entire classes of chemicals that are likely to cause harm. This framework can help manufacturers avoid regrettable substitutions and move towards truly safer replacements.

The Six Classes website provides clear, accessible information about each of these groups: what they are, where they are found, the health and environmental concerns, routes of exposure, and direct steps to take to avoid using them. Blum adds that the website and its resources were created for the design and building community (among others) and encourages those interested in incorporating the Six Classes approach to reach out to GSP with any questions. She advised product manufacturers and large purchasers to “ask for transparency regarding the nature of chemicals in products, require robust toxicity testing of chemicals in their supply chain, and question the use of chemicals in classes of concern.”

Six Classes is just one of GSP’s initiatives. Blum shared some of their accomplishments: “By bringing scientific research to decision makers in government and business, we prevented new flammability standards leading to the unnecessary use of an estimated annual 1.7 billion pounds of flame retardants in the world’s electronics cases. Our scientific and policy work prevented a requirement for flame retardants in pillows and bed coverings in the US. We have also contributed to updating standards so that harmful flame retardants are no longer used in furniture and children’s products across the US and Canada. And our work on PFAS known as “forever chemicals” contributed to their reduced use in carpeting, food packaging, firefighting foam and other products worldwide.”


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