Scientists rank thousands of substances according to potential exposure level

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March 2015

An overwhelming number of chemicals from household and industrial products are in the environment—and hundreds are in our bodies. However, scientists have yet to determine whether most of them cause health problems. Now, a team of researchers has taken the first step toward doing that by estimating which substances people are exposed to the most. The researchers’ new method is published in Environmental Science & Technology (, 2014).

John F. Wambaugh of the US Environmental Protection Agency (EPA) and colleagues note that the risks to human health of any given substance depend primarily on two factors: the potential hazards a chemical presents and how much exposure persons have to the chemical. Yet, public data on these variables are lacking for many substances already in widespread use. About 80,000 chemicals are registered in the United States alone, under the Toxic Substances Control Act, and industry adds 700 to 1,000 new chemicals every year. Directly measuring how much of these substances people are getting exposed to would be a Herculean task requiring the time-consuming analysis of thousands of blood or urine samples. Wambaugh’s team sought a more practical approach.

The researchers developed a mathematical model to predict which household and industrial chemicals have the highest exposure levels. They based their method on answering five simple questions about the substances, such as whether they are used in consumer products or whether they are pesticides. They used this approach to rank nearly 8,000 chemicals, from highest potential exposure level to lowest. While a few of the top 10 were familiar compounds such as DEHP (di-2-ethylhexyl phthalate), a common phthalate that has been shown to cause reproductive problems in rodents, most were substances that scientists know very little about. The researchers say the ranking could help prioritize future efforts that aim to understand potential health risks of thousands of chemicals.

The authors acknowledge funding from the EPA.

In related news, a nonprofit known as Clean Production Action has developed a new tool to establish common benchmarks intended to hasten market movement toward safer chemicals. The tool, called the Chemical Footprint Project (CFP), will enable retailers and other purchasers to evaluate how their suppliers are addressing chemicals in their supply chains. “The CFP results will enable brands to market their progress and success in using safer chemicals,” the group said in a news release.

Mike Schade, campaign director for the Mind the Store campaign of Safer Chemicals, Healthy Families, added, “Like carbon footprinting, the CFP will help enable big retailers to measure their success in moving toward safer chemicals and products for their customers. We feel confident this new tool will empower big retailers to more comprehensively assess and address toxic chemicals in their supply chain. This will help retailers sell products that are safer for their customers and avoid the use of hazardous chemicals linked to chronic diseases.”

The Chemical Footprint Project was founded by the environmental nonprofit Clean Production Action, The Lowell Center for Sustainable Production at the University of Massachusetts Lowell, and the sustainability consultancy Pure Strategies.

For more information about the Chemical Footprint Project, visit