Understanding the Major Limitations of Many Chemical Lists

Lists are among the simplest and most widely used tools today – we make to-do lists of chores that need to be done, and grocery lists before we go to the supermarket.

The internet, and health magazines especially, are brimming with lists of what appear to be expert recommendations on products or activities people should use or avoid, like “Top 10 Superfoods for Heart Health,” or, conversely, “Five Nighttime Activities that Cause Insomnia.”

But, just because a list looks authoritative doesn’t mean you can take it at face value. It’s important to ask some basic questions – to find out more about the quality of information that goes into such lists, whether the lists are kept up-to-date, and whether the information in the list is being interpreted and referenced appropriately.

Developing lists of chemicals for regulatory purposes

Lists can help regulators prioritize chemicals to screen and test for endocrine activity and potential endocrine disruption. At the U.S. Environmental Protection Agency (EPA), for example, regulators rely on two lists to help implement EPA’s widely respected Endocrine Disruptor Screening Program (EDSP).

However, EPA has been careful to highlight some key points about these screening lists:

1. These are not “lists of endocrine disruptors.” In fact, EPA doesn’t have a list of “endocrine disruptors.” EPA assesses chemicals on a case-by-case basis, taking into account the entire body of toxicological evidence available and factoring in actual human exposure levels.
2. EPA selected and prioritized the chemicals on these lists based on their exposure potential, that is, how or to what extent our bodies might come into contact with the substances. EPA began its screening process by focusing on “High Production Volume” chemicals, chemicals that are produced or imported into the United States, in quantities of at least 1 million pounds per year.
3. EPA makes clear: the list “should not be construed as a list of known or likely endocrine disruptors. Nothing in the approach for generating the initial list provides a basis to infer that by simply being on this list, these chemicals are suspected to interfere with the endocrine systems of humans or other species, and it would be inappropriate to do so.”

When “chemical lists” veer off course

Not all chemical lists are developed and explained with such care and clarity of purpose as EPA’s.

“Lists of chemicals to avoid” can be created and published by virtually anyone with a computer or pen and paper – including non-scientists and non-regulators. Some chemical avoidance lists are misused and mischaracterized as definitive science on endocrine disrupting chemicals (EDCs), or as definitive classifications of EDCs.

Some common concerns with these sort of lists of chemicals to avoid include:

• Inconsistent use of definitions and criteria across lists, which can result in chemicals with endocrine activity only (or no endocrine activity at all) being “listed” as an EDC.
• Hazard-only approaches that do not consider factors like potency and real-world exposure scenarios. Sunlight, soy and water all can be hazardous under some conditions; that does not mean they pose a risk under all conditions. So-called “hazard-only” lists are not suitable for regulatory decision-making.
• Lists may carry a veneer of authority that masks the relatively unscientific methods by which they were created. As a result, the public and policymakers may wrongfully assume that each chemical listed was done so based on equally valid and robust science, and that each chemical is equally potent and poses equivalent risk, when the opposite might be true.
• Lists are problematic not only for the substances they inappropriately reference, but also for the ones they don’t. Some might believe that the absence of a chemical from a list is evidence that a chemical is safe, when in reality that substance may not have been assessed in the first place. This can lead to chemicals with years of safety research being pulled from the marketplace and substituted with substances for which far less safety information may exist.

For more information, visit EndocrineScience.