March 7, 2013 -- Lisa Leake's children used to love the taste of Kraft's Mac & Cheese, the bright orange pasta that comes in the signature blue box. But she began to worry about the additives -- yellow dye 5 and yellow dye 6, which she says add nothing to the flavor and may be dangerous to kids' health.
Leake and fellow North Carolina food blogger Vani Hari did some investigating and found that Kraft makes the same Mac & Cheese for its consumers in the United Kingdom, but because of stricter rules regarding additives, it is dye-free.
There, Kraft uses natural beta carotene and paprika to make it almost the same color.
Leake and Hari say the yellow dye serves only "aesthetic purposes." They say they worry that food colorings have been associated with hyperactivity in children, allergies, migraine and, because yellow dyes are petroleum-based, maybe cancer.
Now the two women have posted a petition on Change.org, asking Kraft to offer Americans the same additive-free Mac & Cheese they sell in Europe. So far, the petition has 25,000 signatures and growing.
Leake, 35, and Hari, 33, taste-tested the two versions of Mac & Cheese and posted it on YouTube. They said they found "virtually no difference" in color or taste.
Leake said her children actually liked the U.K. version better.
"We know it could cause harm and doesn't add any benefit, so there is no reason to put it in there," said Leake, who writes the blog 100 Days of Real Food and whose daughters are 5 and 8. "Kraft has already formulated a version without it. We tasted it on camera and they taste the same."
The women wrote a letter to Kraft executives asking them to take the yellow dyes out of the American version.
Kraft spokesperson Lynne Galia responded to ABCNews.com in an email, saying that, "The safety and quality of our products is our highest priority and we take consumer concerns very seriously."
"We carefully follow the laws and regulations in the countries where our products are sold," she said. "So in the U.S., we only use colors that are approved and deemed safe for food use by the Food and Drug Administration."
Knowing that some Americans "prefer foods without certain ingredients," Kraft said it provides at least 14 other Mac & Cheese products without added colors and with natural food colors.
The yellow dyes have been banned in countries like Norway and Austria and are being phased out in the United Kingdom, according to the petition.
"We both grew up eating this product, Lisa used to feed it to her kids, and it's available at almost every grocery store across the country," said Hari in the petition. "Our kids deserve the same safer version that our friends get overseas."
Leake and Hari say in their petition that in addition to hyperactivity, these dyes can have a "negative impact on children's ability to learn."
Some countries require warning labels on products that contain color additives, according to Hari, who writes the blog Food Babe.. "That's the reason why companies are phasing out dyes," she said.
"[In the United States], we have this precautionary principle," she said. "We have to go through crazy, rigorous things to prove harm, rather than safety."
Both yellow dyes in question are fully legal and approved by the FDA, which is responsible for food safety. More than 3,000 additives are approved for food.
"Today, food and color additives are more strictly studied, regulated and monitored than at any other time in history," according to the FDA website on the topic.
To market a new food or color additive, a manufacturer or other sponsor must first petition the FDA for its approval. Since 1999, indirect additives have been approved by a premarket notification process requiring the same data as was previously required by petition.
But Leake and Hari cite a 68-page report from the Center for Science in the Public Interest, "Food Dyes: A Rainbow of Risks," which outlines various studies on the health effects of food coloring.
The center was founded by scientists when consumer and environmental protection awareness was growing in 1971. It advocates for nutrition and health, food safety and alcohol policy.
The report was based on government studies from the National Toxicology Program and recommends removing yellow 6 from the market.
Both dyes used in the Kraft product contain benzidine 4-amino-buphenyl, a manmade product derived from petroleum. In a "too brief" mouse study, yellow 5 showed risks of hyperactivity in children, according to the report; yellow 6 was associated with adrenal and testicular tumors and no studies were done in utero.
Hari said she was inspired to see if there were other products that contained additives banned overseas.
"It was shocking to see hundreds of ingredients that were banned in other countries and were used in American products," she said.
"A can of Pringles in the U.S. looks the same as in the U.K. or Europe and the ingredients are totally different."
For example, French fries at McDonald's in the United Kingdom contained only potatoes, oil and salt. In the U.S., they contain a preservative.
This is not the first petition to address food additives. Last fall, Sarah Kavanagh, a 15-year-old student in Mississippi, started a Change.org petition to get PepsiCo to stop using brominated vegetable oil in its Gatorade.
The ingredient, which was used to prevent some flavors of the drink from separating, has been associated with possible neurological disorders and altered thyroid hormones. It has been banned in some other countries.
The petition attracted more than 200,000 backers. Last month, Gatorade announced that they would be removing the ingredient, but said the decision wasn't in response to Sarah's petition.
Hari said she was "inspired" by the teen's petition. "Lisa and I were really encouraged to take the next step and create change."
Leake said she no longer lets her children eat Mac & Cheese and makes sure they have a healthy diet filled with fresh ingredients. But, she added, if the U.K. version of the product were available in the U.S., she would allow it at the dinner table again.
As for food dyes, she said, "They provide no value to the food and no nutrition, but they do pose a risk. It's a no-brainer."