Brominated flame retardants lately are under intense scrutiny because research has shown that they are building up in people's bodies, including breast milk, around the world. Designed to slow the spread of flames, they are added to polystyrene foam cushions used in upholstered furniture and children's products, as well as plastics used in electronics. Research in animals as well as some human studies have found links to impaired neurological development, reduced fertility, early onset of puberty and altered thyroid hormones.
BVO may not be in use today as a flame retardant in furniture foam, but patents in Europe — granted earlier this year to Dow Global Technologies—and in the United States —granted in 1967 to Koppers Inc.—keep that possibility alive.
"There are some concerns [about BVO] because people are worried that maybe it has the behavior, [and] potential health effects similar to brominated flame retardants," said Heather Stapleton, an environmental chemist at Duke University who specializes in studying brominated compounds.
Soda makers and industry groups say they are not concerned about the safety of brominated vegetable oil, saying their products meet all government standards.
"This is a safe ingredient approved by the FDA, which is used in some citrus-based beverages," said Christopher Gindlesperger of the American Beverage Association, which represents PepsiCo, maker of Mountain Dew. "Importantly, consumers can rest assured that our products are safe and our industry adheres to all government regulations."
Chris Barnes of the Dr. Pepper Snapple Group, makers of Squirt and other drinks that contain BVO, echoed that response.
"All ingredients in Dr. Pepper Snapple Group products meet FDA and other regulator requirements," Barnes said.
Some experts are unconvinced, saying that the FDA standards are based on decades-old data.
"Compounds like these that are in widespread use probably should be reexamined periodically with newer technologies to ensure that there aren't effects that would have been missed by prior methods," said Charles Vorhees, a toxicologist at Cincinnati Children’s Hospital Medical Center, who studied BVO's neurological effects in the early 1980s. "I think BVO is the kind of compound that probably warrants some reexamination."
Toxicity testing has changed dramatically in the past few decades. Multiple generations of animals now can be tested for neurodevelopmental, hormonal and reproductive changes that weren't imagined in the 1970s and early 1980s.
"I am no toxicologist, but I think that the toxic evaluation of chemicals has been improved since then," Vetter added.
In 1970, scientists in England found that rats on a six-week diet containing 0.8 percent brominated maize oil had stockpiles of bromine in their fat tissue. The bromine stayed there even after the rats returned to a control diet for two weeks.
Around the same time, a study confirmed that bromine was building up in humans. Researchers measured the serum levels of people in the United Kingdom—where BVO was in use—and in their counterparts in the Netherlands and Germany, where BVO was not used.
"During this time UK citizens had higher bromine serum levels compared to the inhabitants of Germany and the Netherlands," Vetter said. The largest amounts of lipid-bound bromine were found in tissues from children in the UK, according to the study.