(NHI Nanoblog)Regulators around the world are struggling to define what a “nanomaterial” is, largely so they can get to work on regulating the super-small substances that are the backbone of the growing field of nanotechnology.
University of Michigan Photo
Meanwhile Andrew Maynard, an expert on risk science and a veteran of the nano research world, is arguing that the search for a precise definition is getting in the way of the important work of deciding what’s actually harmful — and what’s not — in this arena.
In a new commentary just out in the journal Nature, Maynard puts it simply: “A ‘one size fits all’ definition of nanomaterials will fail to capture what is important for addressing risk.” (The journal has the full piece behind a paywall, but Maynard has linked to an earlier version on a blog he writes for.)
Maynard, now the director of the University of Michigan’s Risk Science Center, knows what he’s talking about. He’s been studying small particles for two decades, moving into the nano field as questions about the ultra-tiny particles (a nanometer is a billionth of a meter) began to grow. Maynard has worked with the National Institute for Occupational Safety and Health, the National Nanotechnology Initiative, and the Project on Emerging Nanotechnologies. (He also blogs at 2020 Science.)
Nanotechnology leverages the often-unique properties of super-small particles to create products with amazing qualities. These materials can make better batteries or lighter and stronger bike frames, as well as new medical instruments and medicines that can save lives. They’re increasingly common in consumer products, from “mineral-based” sunscreens to stain-repellent paints.
These nanomaterials are believed to hold great promise for a wide variety of applications. But shrinking these substances can change their properties, and scientists are struggling to figure out whether, how and why that shift can make them dangerous in the process.
Maynard freely admits he used to be one of the scientists pushing for a definition—a position that has wide support. But in the past few months, he’s ruminated about whether that’s the best approach. The Nature piece, as he discusses in the blog post, is the result of those thoughts.
So, what should policymakers be focusing on? Maynard says regulators should instead settle on a set of “trigger points” that prompt closer scrutiny of a material at the super-tiny scale. Those points should include size as well as surface area, which seems to matter a great deal when a familiar substance is engineered to be smaller. But other properties should also be considered, he argues, and they should be specific to a material, as well as flexible enough to allow for changes if the scientific evidence suggest them.
“Such regulatory sophistication will obviously take a lot of work. Much more research is needed to pin down how much a material would need to change to trigger a regulatory red flag: should a 1 percent change in mean particle size of a material previously determined to be safe, say, raise concerns, or should it be a 50 percent change?” he writes. “But enough is known today for an expert panel to begin determining key attributes and preliminary trigger points for many materials.”
Maynard says definitions have tripped up regulators in the past, offering the example of the asbestos-contaminated vermiculite that has poisoned the town of Libby, Mont. Vermiculite, which went into insulation, cement and even cat litter, can contain asbestos, which burrows into the lungs and causes serious diseases.
Yet the Libby vermiculite “slipped through the regulatory net for many years because it didn’t fit the official definition of asbestos,” Maynard writes. The town, declared a Superfund site, is still struggling with the aftermath of the deadly contamination.
Regulators need to be wary of making that kind of mistake again, Maynard says. Even assuming nanomaterials are a unique class of materials could cause problems. But he calls the recent nano guidelines issued by the White House, which pointedly note that “a focus on novel properties and phenomena observed in nanomaterials may ultimately be more useful than a categorical definition based on size alone,” a step in the right direction.
Maynard’s commentary is sure to set off a new round of debate among those thinking hard about the subject. It’ll be interesting to see where this goes.