WASHINGTON — The U.S. Environmental Protection Agency (EPA) has ordered a New Jersey company to stop selling its plastic food storage containers because they contain nanosilver, an unregistered pesticide.

The company, Pathway Investment Corp., claims the nanosilver has antibacterial properties that reduce the growth of mold, fungus and bacteria, reducing opportunities for food spoilage. But federal regulations are clear that for any company to make such claims, the products must first be properly tested and registered with EPA.

Pathway is barred from selling its Kinetic Go Green Premium Food Storage Containers, Kinetic Smartwist Series Containers, Tritan Food Storage, and StackSmart Storage containers.

Pathway could not be reached for comment.

“Claims that mold, fungus or bacteria are controlled or destroyed by a particular product must be backed up with testing so that consumers know that the products do what the labels say,” said EPA Regional Administrator Judith Enck. “Unless these products are registered with the EPA, consumers have no information about whether the claims are accurate. The EPA will continue to take action against companies making unverified public health claims.”

In addition to the order sent to Pathway, EPA also issued warning letters to Amazon, Sears, Wal-Mart and other retailers directing them not to sell the affected products.

Silver is known for having antibacterial properties and is frequently used as a coating for externally used plastic medical devices. But scientists are still studying the possible adverse effects of nanosilver, silver particles of between 1-100 nanometers in size, when used internally. In a Canadian study released in January, researchers found that algae reacted negatively to nanosilver, which stopped photosynthesis.

EPA officials said part of the reason companies are required to test their products and register them with the EPA is that making blanket statements about a chemical or additive can be difficult. Part of the registration process is qualifying that a product does not put human health at risk when used as it is intended, said EPA spokesman John Martin.