09 April 2011

Perfluorooctanoic Acid and Other Big Words

We have all heard a lot about BPA in the news with baby bottles, and we're starting to hear more about pthalates and parabens with baby toys and cosmetics. It seems that PFOA seems to be greatly overlooked. After a question I received on my blog, I  realized that I didn't really know a whole lot about the problems with non-stick cookware. I knew that it's bad because there are nasty chemicals in there that do bad things, but honestly, that's about it.

What is it and where is it used?

The big long name for PFOA is perfluorooctanoic acid. It is a man made chemical that is used in the manufacturing process of fluoropolymers.  They are used for fire resistance, and the ability to repel oil, stains, and water. Here's a list: microwave popcorn bags, fast food wrappers (that's not waxed paper!), candy wrappers, pizza box liners, stain resistant carpet (Stainmaster), textiles (Scotchguard), treated apparel (such as Gore-tex), non stick pans (Teflon), wood and stone tile sealant, floor wax, dental floss, dust, shampoo, nail polish, the Metrodome roof in Minneapolis, fireworks, flares, solid fuel rocket propellants, armor piercing bullets (to prevent wear on the firearm), plumbing thread seal tape, fire fighting foam, lab equipment, some types of grafts used to bypass stenotic arteries and slippery surfaces to prevent insects from climbing. I'm sure there are more but that's what I could come up with. It is everywhere.

There are only a few companies that manufacture PFOA. They are DuPont, 3M, Clariant GmbH, Daikin Industries and Asahi Glass. DuPont claims that PFOA is absolutely essential, but 3M has developed a replacement for it and  has completed it's phase out in 2002.

It's currently unknown which sources are of the highest concern when it comes to the absorbtion of PFOA in people.  There are however, low levels of PFOA throughout the population. The people in the area around DuPont's West Virginia plant are higher than average with medium blood serum levels, while the blood serum levels of workers within the plant are considered very high. There is some evidence that tap water (which is not passed through a carbon filter) may be a major source for the general population, due to some plants' waste water being passed on to the municipal treatment facilities.

What's so bad about it?

PFOA is very persistant in the environment and bioaccumulative, remaining in humans and animals for a very long time. It has been linked to thyroid disease, cancer of the liver, prostate, testicles, bladder and pancreas, reduced birth weight, developmental delays, endocrine disruption, neonatal mortality, disruption of lipid metabolism, altered insulin and leptin, infertility, increased risk of ADHD, later onset of puberty and facial birth defects.

How much PFOA is in things?

The USEPA conducted a study of 116 different products to determine the levels of PFOA. The units used are nanograms per gram or parts per billion.

Pre-treated carpets <1.5 to 462
Carpet care liquids 19 to 6750
Treated apparel 5.4 to 161
Treated upholstery .6 to 293
Treated textiles 3.8 to 438
Treated non woven medical garments 46 to 369
Industrial floor wax and wax removers 7.5 to 44.8
Stone tile and wood sealants 477 to 3720
Membranes for apparel .1 to 2.5 ng/cm square
Food contact paper <1.5 to 4640
Dental Floss <1.5 to 96.7
Thread sealant tape <1.5 to 3490
PTFE cookware <1.5 to 4.3

Microwave popcorn is a major avoidable household source of PFOA. When the bag is heated, the PFOA transfers from the bag's coating, to the oil, and it is ingested. If you're worried about your Teflon pan, the popcorn is more serious. Hot air popcorn is just as easy, tastes better, there is less waste, the poppers are inexpensive plus you can put exactly what you want on there (like REAL butter.. yum).

Now on to the cookware. The non stick coating (Teflon) is known as polytetrafluoroethylene (PTFE).  Manufactures say that PFOA is used in the manufacturing of the nonstick cookware but does not remain due to heat curing. The non stick coating, intact, has very low levels of PFOA, and this has been proven in a study by the USEPA. However, the fluorotelomers can be metabolized to form PFOA once you start cooking.
PTFE deteriorates when it reaches 500F, and decomposes at 662F.  However the byproducts have been found to be lethal to pet birds at temperatures as low as 464F.  In my opinion, if there is a gas in my house that can kill a bird, it has no place in my house.  So with that, I'm forced to remember a strange incident as a child where I found my two zebra finches, Rico and Zoe, feet up in their cage. 

Some sources say not to worry about reaching temperatures that high because most oils used in cooking have a smoke point under 450F. A study in an article by Good Housekeeping found different results by testing the temperature in the following scenarios: 

Scrambled eggs cooked on medium for 3 minutes in a lightweight pan : 218F

Chicken and pepper stirfry cooked on high for 5 1/4 minutes in a lightweight pan : 318F

Bacon cooked on high for 5 1/2 minutes in medium weight pan : 465F

An empty lightweight pan, preheated on high for 1 3/4 minutes : 507F

2 tablespoons of oil preheated on high for 2 1/2 minutes in a lightweight pan : 514F

Hamburgers on high for 8 1/2 min in a heavy pan : 577F

Steak on high for 10 minutes in a lightweight pan : 656F
So with those results some general guidelines:

Eggs and stirfrys should be okay. 
Don't cook on high. 
Don't preheat the pan on high, dry or not.
Don't use non-stick for searing meat.

Contrary to popular belief, if you ingest the flaking bits of the coating, the PFOA most likely won't be absorbed by your body.  However if there are flaking bits and scratches on the pan, they are more likely to release toxins, and you should toss it. DuPont estimates the lifespan of a Teflon pan to be 3 to 5 years. 

This brings me to another point. What happens with all these discarded non-stick pans? Why do we always have to throw everything away these days? Assess how much you love your Teflon and whether you're sure to always use it at low temperatures, and avoid scratching it. If it has scratches, it has to go.  Maybe it's time to cook on high if you want to, use a metal utensil if it's what is handy, and stick to (or switch to) stainless steel.

1 comment:

  1. Hi Amber — I applaud the idea of creating a safer home, and because there’s so much misinformation out there about Teflon, I’m not surprised that you are concerned. I’m a representative of DuPont though, and hope you’ll let me share some information with you and your readers so that everyone can make truly informed decisions.

    Regulatory agencies, consumer groups and health associations all have taken a close look at Teflon. This article highlights what they found — the bottom line is that you can use Teflon without worry.


    I’d truly be glad to share additional information about it if you are interested, and appreciate your consideration of this comment. Cheers, Sara.