Snacking On Cereal Packaging
The Washington Post's continued coverage of the massive Kellogg's 28 million cereal box recall in June, when 2-methylnaphthalene from the packaging percolated into the cereal, and yesterday's news that Congress is now investigating that recall are good reminders that for any food you consume, a small part of the wrapping inevitably ends up in your body, too. Ditto for pharmaceutical drugs.
Last summer I wrote about how food and pharma companies are starting to deal with these packaging leachables, and so a couple of people at C&EN asked me to speculate on how the 2-methylnaphthalene had ended up in America's Froot Loops.
According to the Kellogg's press release, the voluntary recall occured due to an "uncharacteristic off-flavor and smell coming from the liner in the package." The CDC's website notes that naphthalene is often found in moth balls and deoderant, but it can also be found in resin (presumably how Kellogg's thinks the 2-methylnaphthalene ended up in the cereal box liner) and printing dye ingredients. Substituted naphthalenes have high vapor pressure, which means they can migrate through all sorts of packaging, including cardboard and polyolefins.
I have no reason to debate Kellogg's conclusion that the 2-methylnaphthalene did in fact come from the cereal box liner. But I wonder if the company also checked into the possibility that the 2-methylnaphthalene came from printing dyes on the cardboard box, since dye ingredients have a particular penchant for slipping through food and pharma packaging of all kinds.
For example, last year Europe also had a cerealgate, when 4-methylbenzophenone was found in chocolate muesli--which is a granola-like breakfast cereal eaten with near religious fervor on the continent. In the European cereal recall, the 4-methylbenzophenone was a component of the printing ink typically found on the outside of the box that had migrated to the inside.
Another way for printing ink chemicals to enter food from cardboard containers is when the packaging is recycled from paper products that possess dyes containing the chemical. A quick web search brought up this, albeit 0ld, 1994 reference to rice and pasta contaminated by six diisopropylnaphthalenes which probably came from the recycled paper used to make the cardboard packaging.
When packaging printing dyes end up in food or drugs, it doesn’t always mean they’ve percolated through the packaging. Sometimes food and drugs can be contaminated by the way packaging is stored prior to use. For example, packaging is often rolled up or packed in such a way that the printed exterior is touching the non-printed interior, creating opportunities for printing ingredients to taint the side of the packaging which contacts or is closer to the product. This led to a major recall in 2005 of baby formula stored in Tetrapak packaging that had been rolled up in this way.
There are so many routes for packaging materials to enter food and drugs it's a bit mindblowing: At a conference last spring in Barcelona for people in industry and regulatory agencies whose job it is to worry about possible sources of packaging leachables in pharmaceutical drugs, we heard ample examples. For instance, an FDA participant told us that a set of injectible protein drugs in disposable syringes were spoiled because a tungsten filament used to poke a hole through the tip of the syringe needle had left behind a tungsten oxide salt residue that later percolated into the liquid-drug formulation causing protein aggregation.
In the case of the Kellogg's cereal, 2-methylnaphthalene caused some nausea and vomiting. What might it be next time? Here's an extentive analysis by the Environmental Working Group that argues the FDA should do much more about chemicals that leach from packaging.