"As part of FDA's overall commitment to ensure the safety of the food supply, the agency uses an extensive, science-based process to evaluate the safety of food additives," said FDA spokeswoman Theresa Eisenman. "Under FDA regulations, safety for food additives means that there is a reasonable certainty of no harm when an additive is used within the intended conditions of use."
Eisenman told ABCNews.com that FDA is currently collecting data on the use of azodicarbonamide in bread.
"The agency continues to monitor the safety of food additives, including azodicarbonamide, and is prepared to take appropriate action if there are safety concerns," she said.
Hari said she had no idea what the quantities of the additive were in Subway's bread. "I've asked the question to Subway and no response," she told ABCNews.com "Someone would have to test it."
ABCNews.com sent an email to the corporate communication director for Subway and called for comment several times, but did not get a response on the quantities of the additive.
Subway has also launched an ad blitz for the upcoming Sochi Winter Olympics, and has used celebrity athletes such as light heavyweight boxer Mike Lee in its TV ads. The company has also promoted its $5 foot-long sandwich in an ad that features former Olympic speed skater Apolo Ohno and Australian snowboarder Torah Bright.
Subway has pledged to spend $41 million over three years for its healthier kids menu with ads using the Muppets, according to Business Week. Its kids menu includes many healthy items, such as fruit, vegetables, non-sugary drinks and lean dairy products.
But commenters today on Subway's Facebook page were buzzing about Hari's petition. "Mmm, tasty, tasty," said one urging the company to remove the additive from its bread.
Case reports and epidemiological studies by the World Health Organization say that azodicarbonamide can induce asthma, other respiratory symptoms, and skin sensitization in exposed workers. "Adverse effects on other systems have not been studied," says its report on the additive. There have been no human studies.
Hari notes that in Singapore, companies can be fined up to $450,000 or jailed for using azodiacarbonamide in food products.
"What really broke the camel's back is when I realized Subway has reformulated its honey oat bread overseas and are using completely a different ingredient list that doesn't have the chemical. My question is, why can't we get the chemical out of our bread?"
"The power lies within the food companies to make changes quickly," she said. "You don't have to wait for the government. Many are already doing it. And they don't have to reinvent the wheel -- other countries around the world are -- to safeguard our health."
Hari was previously invited to meet with Chik-Fil-A leadership to consult on improvements in ingredients. She also petitioned Kraft to remove food dyes from its Mac & Cheese and last year they responded by removing all dyes from products aimed at children.