The regulator's report labelled the incident "serious", explaining that the workers had not been provided with proper safety training and were not authorised to work in the tanks.
Milk chocolate is generally melted at around 45C before tempering. This is slightly above the recommended safe temperature for a bath but unlikely to cause scalding unless maintained for a long period of time.
The workers were both wearing safety clothing which may have protected them from more serious burns.A representative for Mars Wrigley welcomed the outcome of the investigation.
"The safety of our associates and outside contractors is a top priority for our business," said the spokesperson.
"As always, we appreciate [the Occupational Safety and Health Administration's] collaborative approach to working with us to conduct the after-action review."
Mars and Wrigley are each more than 100 years old and are two of the biggest confectioners in the US. In 2008, Mars agreed a takeover of Wrigley worth $23bn (£11.6bn), making them the largest maker of sweets and chocolate in the world.
In addition to Dove, the Mars Wrigley produces several popular products such as M&Ms, Snickers and Twix.
