The tubes, like other nanomaterials, are only a few ten-thousandths the diameter of human hair.

Nanomaterials, 'The Washington Post' points out, are already found in cosmetics, clothing and otherproducts, but these items do not fall under the EPA's regulatory domain.

EPA officials judge applications subject to the Toxic Substances Control ACT (TOSCA), a law dating from the mid-1970s that applies to chemicals.

Meanwhile, the paper noted that a debate is on among government officials, industry representatives, academics and environmental advocates over how best to screen the potentially toxic materials emerging from nanotech.

Last week a group of academics, industry scientists and federal researchers, working under the auspices of the non-profit International Life Sciences Institute, outlined a set of principles for determining the human health effects of nanomaterial exposures.

By year end, the EPA plans to release a proposal on how companies should report nanomaterial toxicity data to the government.