The Neighborhood Toxicologist: Popcorn, hold the PFOA

Wednesday, February 07, 2007

Popcorn, hold the PFOA

Cruising through the latest news in the journal Environmental Science and Technology, I came across an article on PFOA (you know, those fluoropolymers that just a couple of years ago resulted in people tossing out their old non-stick pans, and returning to the heavy iron frying pans that could really knock someone out,) in both non-stick pans and, even more interestingly in the coating of microwave popcorn bags. The chemicals are known to accumulate in the environment (I've got a longer article on this in Green Living if you want to read more.)

The work, led by Kurnthachalam Kannan, published just this month in ES&T, reveals that yes, PFOA and related chemicals (for example chemicals called fluorotelomer alcohols or FTOHs) are released into the air from pans heated to normal cooking temperatures, and even into water boiled in these pans. The good news, was that the amounts released, in most cases, was reduced with repeated use.

But here's what's interesting, Kannan's group also reported that PFOA and FTOHs were released into the air from the packaging used for certain (unnamed brands) of microwave popcorn, and in some cases the amount of FTOHs released from popcorn bags was greater than amounts released from cookware.

SO, the next time you cook popcorn, you might want to do it the old fashioned way, in your new iron pot!

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Some history: Toxicology as a formally recognized scientific discipline is relatively new (mid 1900’s) although the science itself is thousands of years old. Consider the potential results of early trial and error experiences of hunter-gatherers for whom identifying a toxic plant or animal was a life or death situation. Some of the most poisonous substances known today are naturally produced chemicals including Ricin from castor beans or tetrodotoxin from the puffer fish. Early humans’ careful observation of plants or animals with toxic characteristics such as frogs containing curare, were put to use not only for avoidance of toxic substances but for weapons as well. Additionally, many naturally derived poisons were likely used for hunting, medicinals (the Egyptians were aware of many toxic substances such as lead, opium and hemlock as early as 1500 BCE), and eventually for the political poisonings practiced, for example, by the early Greeks and Romans.

As humans sought to better understand natural compounds that were both beneficial and harmful, there was very little if any clear understanding of the fundamental chemical nature of substances. That is, there was no connection between the ‘extract’ or ‘essence’ of a poisonous plant or animal and any one particular chemical that might cause toxicity. In fact, an awareness of chemistry in its modern form did not occur until the mid to late 1600’s[i]. So it is ironic that Paracelsus, a physician from the sixteenth century and one of the early “Fathers of Toxicology” had no clear understanding of chemistry as we know it today. He along with many others at that time apparently believed that all matter was composed of three “primary bodies” (sulfur, salt, and mercury)[ii]. Yet Paracelsus also coined the now famous (or infamous) maxim of the newly emerging discipline of toxicology:

“All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy.” (Paracelsus,1493-1541)

This phrase and Paracelsus’ name are committed to memory by hundreds of new toxicology students each year and has become the ‘motto’ of toxicology. Interestingly, if one takes Paracelsus at face value, it appears he was referring to potential remedies. This is an important point, since in recent years some have turned this around to suggest that exposure to very small doses of highly toxic chemicals (such as dioxins) might not be an problem! These days most of us are well aware of the fact that overdosing can turn remedies to poisons, even with apparently innocuous drugs such as aspirin and Tylenol.

[i] Ball, P. 1999. Life’s Matrix: A Biography of Water. Farrar, Straus and Giroux, NY, NY.

[ii] Ball, 2001.