"Unquestionably, Amazon is falling short of its commitment to keeping safe those consumers who use its massive platform," the three Senate Democrats wrote in the latter sent to Bezos on Thursday.
The letter mentioned the recent investigation by the Wall Street Journal that found more than 4,000 items for sale on Amazon's site that "have been declared unsafe by federal agencies, are deceptively labelled, or are banned by federal regulators."
The investigation revealed the availability of myriad problematic items on the e-commerce site including defective helmets, toys and cosmetics incorrectly labelled as US Food and Drug Administration (FDA)-approved, unregistered pesticides, and pain relievers lacking appropriate FDA warning labels, among others.
The letter mentioned the traumatic story of a family whose life Amazon's negligence changed forever.
The incident involved 23-year-old Albert Stokes who died in a motorcycle crash in 2014 when his helmet came off. The helmet, purchased from Amazon, was not compliant with federal safety standards and had been recalled.
While the helmet in question has been removed from Amazon's site, many other problematic items remain on Amazon's platform, the letter mentioned.
Senators Richard Blumenthal, Robert Menendez and Edward Markey asked why the safety efforts at Amazon have failed to prevent the sale of mislabelled, recalled and other unsafe products.
They also asked what steps Amazon is taking to identify and remove problematic items from the platform.
The lawmakers asked Bezos to reply to their questions by September 29.
In response to the WSJ report, Amazon is blog post said that it invests "significant resources to protect our customers and have built robust programmes designed to ensure products offered for sale in our store are safe and compliant".
( With inputs from IANS )