Today, let’s look at the Environmental Working Group’s (EWG) warning about potassium bromate, which is number two on the group’s dirty dozen food additive list.  Again, EWG’s alarmist claims are weak and mushy.

Potassium bromate is added to dough in the making of bread to help improve texture and elasticity of the bread and make it airy and light. It can be toxic to humans exposed to relatively high, concentrated levels of the substance. But trace levels used in bread are too low to worry about, and the chemical is mostly eliminated through cooking. When the dough is cooked the chemical changes into potassium bromide, which is inert as EWG admits.

Still, EWG makes a big deal because a handful of rodent studies show that rats fed or injected with relatively high levels of potassium bromate form tumors. It’s worth noting that the rats did not suffer any ill effects when fed bread made with the additive; they only formed tumors from exposure to concentrated levels of the additive alone. That is not the same as human consumption of bread made with trace levels of the chemical, which is mostly cooked away.  In addition, these studies are of limited relevance to humans because of interspecies differences and vastly different exposure levels and routes.  

Scientist Derek Lowe highlights further why these rat tests are not particularly relevant to human exposures.  He notes:

“Bromate is used in some (but not all) bread flour at 15 to 30 parts per million, and if the bread is actually baked properly, there's none left in the finished product. But for illustration, let's have someone eating uncooked bread dough at the highest level, just to get the full bromate experience. A 75-kilo human (and many of us are more than that) would have to take in 457 mg of bromate per day to get to the first adverse level seen in rats, which would be. . .15 kilos (about 33 pounds) of bread dough per day, a level I can safely say is unlikely to be reached.”

EWG’s other “evidence” is the fact that the International Agency for Research on Chemicals (IARC) has classified potassium bromate as a “possible carcinogen.” Remember, such classifications do not mean that trace exposures to chemicals pose serious risks. They basically mean that some level (relatively high for long duration) may cause cancer. According to IARC, there’s “inadequate evidence” from human studies that potassium bromate is carcinogenic. It’s placed in the “possible” category simply because of the studies on rodents, which certainly have many limitations. 

For some perspective, consider the fact that IARC places a number of chemicals that people safely consume every day in the “possible” carcinogen category. For example, it places substances naturally formed in pickled foods, coffee, and myriad fruits and veggies from broccoli to cauliflower to peas and celery on the list of “possible carcinogens.” But we intuitively know that trace levels of such chemicals don’t make these healthy foods dangerous.

Thanks to hype that groups like EWG constantly push about this chemical, you will see stories all over the web complaining that the United States allows bread producers to use this “dangerous” chemical while Europe and other nations banned it. But these bans don’t show that the Unites States is behind the times. They only show that other governments have foolishly fallen for the hype.

This post is part three of a series on the EWG’s Dirty Dozen Guide to Food Additives.  See parts one and two more information.