A United States senator is formally requesting that the Federal Trade Commission investigate what he called “misleading safety claims and deceptive practices” among helmet manufacturers and refurbishers.

In a letter sent Monday to the commission’s chairman, Jon Leibowitz, and obtained by The New York Times, Senator Tom Udall, Democrat of New Mexico, contended that advertisements from two primary helmet companies could violate the Federal Trade Commission Act, which prohibits misleading descriptions of the protective qualities of a safety device, particularly one used by children.

Udall took specific aim at Riddell, the official helmet manufacturer of the N.F.L., for its prominent claim that its popular Revolution models decrease concussion risk by 31 percent  which has been criticized by experts for years. Udall also cited how the limited test standard to which new and used helmets are held, overseen by the National Operating Committee on Standards for Athletic Equipment (Nocsae), can convey a level of concussion-related protection that the headgear is not shown to provide.

“Athletes, coaches and parents today are increasingly aware of the danger of concussion, and this awareness influences decisions about buying new and reconditioned football helmets,” wrote Udall, who last month initiated an inquiry into football helmets by the Consumer Product Safety Commission. “Athletes who have already suffered a concussion  as well as their coaches and parents  may be particularly susceptible to misleading marketing claims about helmet safety.”