POTWs: Big Trouble with Nanowaste

Publicly owned treatment works (POTWs) use an amazing arsenal of equipment to prevent large troublemakers, such as animal carcasses and tree limbs, from entering their wastewater treatment processes. However, they don't yet have the necessary technology to keep out nanoparticles, which some worry could have a much worse impact on the quality of the water these plants treat.

Just as it is hard to understand how big the potential problems with nanotechnology could be, it’s also difficult to fully comprehend how small “nano” really is. Defined as one billionth of a meter, a nanometer is one-hundredthousandth the width of a human hair. Much of the concern is based on how compounds change when they are nano size. For example, at the nano level, some compounds shift from inert to active, from electrical insulators to conductors, from fragile to tough. They can become stronger, lighter, or more resilient. These transformed properties are what account for the infinite variety of applications of nanoparticles, which are defined as anything less than about 100 nanometers in diameter.

The concern is that nanomaterials could affect water and air quality in areas where these compounds are dispersed. At this time, very little is known about nanotoxicology, which might be quite different from the toxicology of the same materials at normal scale. For example, Vicki Colvin, a chemist at Rice University, said recently that the usual way to assess toxicity, by measuring a toxin’s mass, won’t work at the nano level. Nanomaterials have a much higher surface-to-mass ratio, and while this makes them good for such purposes as water filtering, it just as well could cause them to interact with human body cells that their extremely small size allows them to infiltrate.

A newly released report, "Where Does the Nano Go? End-of-Life Regulation of Nanotechnologies," focuses on how little information there is on the environmental fate and effects of nanomaterialcontaining wastes. The report was written by environmental law experts Linda Breggin and John Pendergrass of the Environmental Law Institute and was commissioned by the Project on Emerging Nanotechnologies, an initiative of the Woodrow Wilson International Center for Scholars and The Pew Charitable Trusts. . “POTWs are on the front lines, and they’re not getting enough information,” said Pendergrass on July 26 at a briefing when the report was officially released.

Liquid waste disposed of in waters treated by POTWs is exempt from regulation under the Resource Conservation and Recovery Act (RCRA), according to Pendergrass. The rationale is that regulations issued under the Clean Water Act would address those wastes.

Pendergrass commented that some private manufacturers of nanotechnology products, especially small start-up companies, may be pouring some liquid wastes containing nanomaterials into the public sewage system without the knowledge of the impacted POTWs.

The U.S. Environmental Protection Agency has already begun taking action related to the manufacture of nanotechnology. In November 2006, the agency stated it would regulate nanoscale silver used in washing machines to kill bacteria. EPA’s action was prompted by POTW managers and operators who worried the nanosilver could be released into wastewater by washing machines that contain this nanomaterial.

Under RCRA regulations, a waste generator is required to share with the firm that treats its waste any information it has that will help the waste handler manage it safely, Pendergrass said.

In contrast to actions mandated under RCRA, according to Pendergrass, a company or research institute that is releasing liquid waste with nanomaterials in it is not required to provide POTWs with information to ensure they are working safely with those wastes.

Just as the debate about the possible dark side of nanotechnology has rapidly heated up, so has the commercial success of this new technology. More than $30 billion in products incorporating nanotechnology were sold globally in 2005. By 2014, Lux Research estimates this figure will grow to $2.6 trillion.

Nowadays, with hundreds of nanotechnology products already on the market, one of the questions in greatest need of attention is how various forms of nanomaterials will be disposed of and treated at the end of their use. They may end up in our POTWs, landfills, or incinerators, and, consequently, in our water, soil, or air. Responding to such growing concerns about nanotechnology, EPA has launched its Nanoscale Materials Stewardship Program.

We still have much to learn about the potential risks to human health and the environment posed by nanotechnology and its byproducts. So important is this issue that the ultimate success or failure of this exciting new technology may possibly depend on how fully these issues are addressed. Only when these concerns are resolved can our society in good conscience promote the development of nanotechnology in an environmentally sustainable manner.

This article originally appeared in the 10/01/2007 issue of Environmental Protection.

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