WASHINGTON — Regulators are proposing that food companies that want to use tiny engineered particles in their packaging may have to provide extra testing data to show the products are safe.

The Food and Drug Administration issued tentative guidelines Friday for food and cosmetic companies interested in using nanoparticles, which are measured in billionths of a meter. Nanoscale materials are generally less than 100 nanometers in diameter. A sheet of paper, in comparison, is 100,000 nanometers thick. A human hair is 80,000 nanometers thick.

The submicroscopic particles are increasingly showing up in FDA-regulated products like sunscreens, skin lotions and glare-reducing eyeglass coatings. Some scientists believe the technology will one day be used in medicine, but the FDA’s announcement did not address that use.

The draft guidance suggests the FDA may require food companies to provide data establishing the safety of any packaging using nanotechnology.

Under longstanding regulations, companies aren’t required to seek regulatory approval before launching products containing established ingredients and materials, such as caffeine, spices and various preservatives.

But FDA officials said Friday that foods and packaging containing nanoparticles may require more scrutiny.

“At this point, in terms of the science, we think it’s likely the exemption does not apply and we would encourage folks to come in and talk to us,” said Dennis Keefe, director of FDA’s office of food additive safety.

Keefe said companies are studying whether nanoparticles can reduce the risk of bacterial contamination in certain foods. He said the agency is aware of just one food package currently on the market that uses nanoparticles but did not identify it. He said more are expected in coming years.

The FDA has previously stated its position that nanotechnology is not inherently unsafe; however, materials at the nano scale can pose different safety issues than do things that are far larger.

“This is an emerging, evolving technology and we’re trying to get ahead of the curb to ensure the ingredients and substances are safe,” Keefe said.

In a separate guidance, the FDA laid out suggestions for the use of nanotechnology in cosmetics, a practice which has been in use since the 1990s. Nanoparticles are used in skin moisturizer, mineral make up and other cosmetics.

The FDA has less authority over cosmetics than food additives. Generally, the FDA does not review cosmetics before they launch, and companies are responsible for assuring the safety of their products.

The FDA will take comments on both proposals for 90 days. There is no deadline for finalizing the documents.