A precautionary approach to ENMs in consumer products may prevent a repeat of past episodes in which seemingly invaluable chemical innovations proceeded with little oversight and ultimately caused major health or environmental problems.

If ENMs get into the environment, new routes of exposure open up for humans (through drinking water, for example) and other organisms. Silver nanoparticles, which are used for their antimicrobial properties, have drawn research scrutiny for their environmental fate. Many researchers consider these particles quite likely to enter the aquatic environment because they can wash out of antimicrobial clothing and washing machines and into wastewater—although whether they do so in amounts large enough to matter has been subject to debate. They can also wind up in sewage sludge, which is often applied to farmland as fertilizer.
Silver nanoparticles have been shown to damage cells derived from human and mammalian skin, liver, lung, brain, vascular, and reproductive tissues when evaluated in vitro. At high doses, they have been shown to compromise the blood–brain barrier and cause neurotoxicity in rats and mice.,, A 2008 University of Florida study found that both silver and copper nanoparticles can be toxic to model aquatic organisms including zebrafish, two species of water flea, and the alga Pseudokirchneriella subcapiata.

Unlike the nanomaterials in food or personal care products, which may come into direct contact with consumers’ bodies, those in many other types of goods are securely embedded in a composite matrix. Examples include bicycle parts, tennis rackets, and other sporting goods made lighter and stronger with ENMs such as carbon nanotubes.
But while consumers may not be exposed in these cases, exposures and any attendant hazards are still an issue for the workers who make the goods, says Brown University researcher Agnes Kane. “We really do need to be very careful to limit exposure during the manufacturing process and the fabrication process of these materials,” Kane says. “Once they’re in composites and then used in that way, it’s less hazardous. But then we have to consider end of product life and how they would be disposed of or recycled.”
As this article was going to press, the EPA announced it had awarded $5.5 million to three consortia to support innovative health and safety research on ENMs. According to an EPA press release, the grants “will help researchers determine whether certain nanomaterials can leach out of products such as paints, plastics, and fabrics when they are used or disposed of and whether they could become toxic to people and the environment.”