THEGREENGROK    The Chemical Marketplace

The Chemical Marketplace Series – Bisphenol AF

by Bill Chameides | August 17th, 2010
posted by Erica Rowell (Editor)

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More than 80,000 chemicals are produced and used in the United States. This is one of their stories.

Introducing bisphenol AF, BPA’s more toxic sibling.

By now, you’ve no doubt heard about Bisphenol A (aka BPA) and its potential for toxic mischief when leached from various plastic containers. You’ve probably also heard that companies are now falling all over themselves to declare their products ”BPA-free.” (And some people claim that the public can’t catalyze a national green movement.)

The Chemical Marketplace
A series that looks at chemicals in everyday consumer products
     Alkylphenols and laundry and such »
     Aluminum and antiperspirants »
     Dioxin and eggs »
     Flame retardants and pets »
     Fluoride and water »
     Formaldehyde and no-iron shirts
     Insect repellents »
     Nanoparticles and food »
     PAH and seal coats: A no-brainer »
     PBDE and fire retardants »
     PFOA and popcorn »
     Piperonyl butoxide, a pesticde »
     Propoxur and bedbugs »
     Rotenone, a pesticide »
     Spray foams, sealants, diisocyanates »
     TDCPP and the air »
     Triclosan and toothpaste »
     Trihalomethanes (THM) and
showering »

All in the BP Family

But you may not know that BPA is only one of a cornucopia of chemical bisphenols, or BPs, running amok in the world. (The “BP” referred to here should not be confused with a certain petroleum company that has received a good deal of media attention of late.)

Among the alphabet soup of chemical BPs are BPB, BPC, BPF, BPAF, BPE, and BPS. In fact, the National Toxicological Program lists 38 compounds [pdf] that are structurally similar to BPA. The common thread is that they all begin with the same basic bisphenol chemical structure of C12H10(OH)2 — two phenyl groups each bonded to a hydroxyl (OH) group — then are subtly added to and/or otherwise modified. For example, in the case of BPA, two methyl groups (CH3) are added along with an extra atom of carbon (C) to the basic bisphenol building block.

What About Bisphenol AF (BPAF)?

Well, not all that surprising, given the “F” in its appellation, BPAF has the same configuration as BPA except the hydrogen atoms in the methyl group have been replaced by fluorine atoms. (Technically speaking, substituting fluorine for hydrogen in the methyl groups turns them into trifluoromethyl compounds.)

From the point of view of a chemical engineer, the addition of the fluorine atoms improves BPA’s chemical, thermal and mechanical properties, making it attractive for lots of applications in plastics, electronic devices, optical fibers, and more. Thus, BPAF is one more example of a compound with wondrous new properties produced by replacing hydrogen atoms with halogen atoms (in this case fluorine) in an organic molecule.

But, alas, there is a problem: many of those halogenated compounds turn out to be mixed blessings at best. They can be quite toxic and they can be slow to break down or metabolize in the environment and in the human body. Examples include PBDEs, PCBs , DDT and Freons.

Lots of Unknowns With BPAF

As for BPAF, the fact is we don’t know very much about its toxic properties. But recent results from short-term studies have suggested that it may act as an aggressive endocrine disruptor. Indeed, in 2008 it was one of only six chemicals accepted for further study by the National Toxicological Program.

While that work is just getting started, data trickling in from other sources are not reassuring. There are signs that BPAF may be a more effective endocrine disruptor than BPA. For example, a study published last spring in Environmental Health Perspectives by Ayami Matsushima of Kyushu University in Japan and colleagues suggests that BPAF packs a one-two punch on the reproductive system: effectively shutting off gene receptors that promote reproductive health and inhibit reproductive cancers, while activating the receptor that can promote reproductive cancers.

Okay, that’s not great, but what are the chances any of us are being exposed to BPAF in dangerous quantities? I can’t give you a definitive answer, but here’s what TheGreenGrok team has been able to find out.

It’s rather incredible to me but the National Toxicology Program reports [pdf] that there does not yet exist a comprehensive database on the types of products that contain BPAF. One application that has been documented: BPAF is used in food-contact polymers such as fluoroelastomer gaskets and in hoses used in food-processing equipment. BPAF may also be used in dental resins and plastics used to wrap foods. Not exactly what one would want to hea
r for a potentially toxic compound.

Patent records [pdf] indicate that we haven’t been making BPAF all that long, only since the late 1970s. According to the Environmental Protection Agency’s most recent chemical inventory database from 2006 (the inventory is updated every four years), between 10,000 and 500,000 pounds of BPAF are manufactured, imported or used annually in the United States. Why such a large range? That’s the way EPA does it; here’s the agency’s explanation [pdf].

These amounts, reports EPA, have remained essentially flat since 1986. But are they significant? It’s hard to say since we don’t know that much about how BPAF moves through the environment or whether a significant amount leaches from products and gets into our bodies. Two relevant things to note:

  • On the positive side, the amount of BPAF in use in the United States is considerably less than that of BPA (at one billion pounds or greater).
  • On the other, BPAF has been detected in the environment (albeit at levels lower than that of BPA). A study in Germany found detectable levels of BPAF in about three-fourths of the surface water and sewage samples collected and in more than half of the sediment samples collected.

So that’s the story on BPAF. One of some 80,000 chemicals used here that go unregulated and virtually unstudied. Are the products you use exposing you to BPAF? Your guess is as good as mine.

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