Sunday, August 10, 2008

Gimme a "B"

There’s been a bit of a scare going around the consumer sector lately related to chemicals leeching into water from Nalgenes, baby bottles, and the like. Many times when these types of scares show up they are the result of press release of an initial study that shows a chemical has harmful properties. Consumers then jump the gun and retailers respond in a knee-jerk fashion to pull certain items from the shelves. The particular chemical name in this case that is on the tip of everyone’s tongue lately is BPA (pun intended). So I started a short investigation into some of the properties and effects of the compound in the hopes of finding out what’s really going on here. So, what is BPA? Where does it come from? And is it actually bad for you? Let’s take a look.

BPA is short for bisphenol A. The Chemical Abstracts Service (CAS) number for bisphenol A is 80-05-7. Synonyms for bisphenol A include: 2-(4,4'-Dihydroxydiphenyl)propane; 2,2-Bis(4-hydroxyphenyl)propane; 2,2-Bis(hydroxyphenyl)propane; 2,2-Bis(p-hydroxyphenyl)propane; 2,2-Bis-4'-hydroxyfenylpropan; 2,2-Di(4-hydroxyphenyl)propane; 2,2-Di(4-phenylol)propane; 4,4'-(1-Methylethylidene)bisphenol; 4,4'-Bisphenol A; 4,4'-Dihydroxydiphenyl-2,2-propane; 4,4'-Dihydroxydiphenyldimethylmethane; 4,4'-Dihydroxydiphenylpropane; 4,4'-Isopropylidene diphenol; 4,4'-Isopropylidenebisphenol; 4,4'-Isopropylidene diphenol; Biphenol A; Bis(4-hydroxyphenyl) dimethyl methane; Bis(4-hydroxyphenyl)dimethylmethane; Bis(4-hydroxyphenyl)propane; Bisferol A; Bisphenol. Bisphenol A; DIAN; Diano; Dimethyl bis(p-hydroxyphenyl)methane; Dimethylbis(p-hydroxyphenyl)methane; Dimethylmethylene-p,p'-diphenol; Diphenylolpropane; Ipognox 88; Isopropylidenebis(4-hydroxybenzene); Parabis A, Phenol; (1-methylethylidene)bis-, Phenol; 4,4'-(1-methylethylidene)bis-; Phenol, 4,4'-dimethylmethylenedi-; Phenol, 4,4'-isopropylidenedi-; Pluracol 245, Propane; 2,2-bis(p-hydroxyphenyl)-; Rikabanol; Ucar bisphenol A; Ucar bisphenol HP; beta,beta'-Bis(p-hydroxyphenyl)propane; beta-Di-p-hydroxyphenylpropane; p,p'-Bisphenol A; p,p'-Dihydroxydiphenyldimethylmethane; p,p'-Dihydroxydiphenylpropane; p,p'-Isopropylidenebisphenol; and p,p'-Isopropylidenediphenol. Bit of a mouthful, eh? There will be a quiz later. I didn’t just list those synonyms to be confusing. Sometimes chemical manufacturers will change the names of chemicals on their packaging that are becoming well known to consumers in order to hide their harmful effects or in order to give the appearance that they are actually changing formulations in response to consumer backlash. Can’t hide from me, Jaggoffs.

BPA is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. It exists at room temperature as a white solid and has a mild hospital odor. Polycarbonate plastics have many applications including use in certain food and drink packaging (water and infant bottles), compact discs, impact-resistant safety equipment, and medical devices. Polycarbonate is typically clear and hard and marked with the recycle symbol “7” or may contain the letters "PC" near the recycle symbol. Polycarbonate can also be blended with other materials to create molded parts for use in cell phone housings, a plethora of household items, and parts for cars. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some polymers used in dental sealants contain bisphenol A-derived materials. In 2004, the estimated production of BPA in the U.S. was approximately 2.3 billion pounds, most of which was used in polycarbonate plastics and resins. BPA has received considerable attention in recent years due to widespread human exposures and concern for reproductive and developmental effects reported in laboratory animal studies. It is most commonly described as being weakly estrogenic. This means that it’s a non-biological estrogen mimic and can possibly act as or interfere with processes that involve the hormone estrogen. However, an emerging body of molecular and cellular studies indicate that there is potential for a number of additional biological activities. These range from interactions with cellular components that have unknown biological function to others that help mediate the actions of non-estrogenic hormones, such as androgens and thyroid hormones.

BPA’s harmful effects were uncovered by a laboratory mishap. In 1998, a geneticist noticed that chromosomal errors in the mouse cells she was studying had shot from the 1 or 2 percent that was expected up to 40 percent. She traced the effect to polycarbonate cages and water bottles that had been washed with a harsh detergent. When her team replaced all the caging materials with non-polycarbonate plastics, the cell division returned to normal. This discovery has lead to a profusion of animal studies on the compound. My initial search turned up over 400 articles related to the topic.

So, how exactly do we get exposed to the chemical? If you don’t work at a plastic plant, paper recycling facility, or epoxy resin facility over 90 percent of BPA exposure comes from ingestion...We eat it. BPA can be released from polycarbonate containers when they contain hot or acidic liquids, alcohols, are damaged or old, or are cleaned with harsh or abrasive detergents. It can leech out of cans into canned foods for the same reasons. Infants get a multiple whammy if they are breast-fed. They are exposed through their polycarbonate bottles (that are usually heated in boiling water, contain hot milk or formula and are cleaned after every use), they are exposed through breast milk (from the mother’s consumption of BPA), and they have some environmental exposure from being on the floor and putting plastic toys (and everything else) in their mouths. Kids are just gross. Due to the reasons just mentioned, children have the highest exposure to body mass ratio, and as such they have the highest potential for harmful effects.

I waded through a bunch of rat-based studies for high-dose exposures that showed harmful effects on everything from baldness to obesity to early onset of puberty to reproductive toxicity. The main problem is that exposures on these levels are way out of proportion with non-occupational human exposures. A person would have to eat 1,300 pounds of canned and bottled food per day in order to reach the exposure levels in most of these studies. There are few long-term, low-exposure, human-based studies that have been done. It is true that in most cases the high-dose studies are an indicator that low dosages will have deleterious effects as well, but the backup research is not there for BPA. Oh, by the way, in literally 100 percent of the studies that I looked at that were funded by chemical manufacturers or distributors no harmful effects from BPA were found, but most government-funded studies that I saw found obvious harmful effects. It’s classic tobacco company logic. If you fight legislation, lie or play down science you can get 10 or 15 years more profit out of your product before the legislation starts. Big surprise…

O.K., Dan. Let’s get down to the brass tacks, here. Does this chemical have harmful effects or not? Do I need to worry about getting fat, going bald, growing man tits, and going through menopause? Well, probably, but it most likely has nothing to do with the amount of green beans you eat from a can. Is BPA harmful or not, seriously? The short answer is possibly. The EU states that there is at present no need for further information and/or testing or for risk reduction measures beyond those which are being applied already. This applies in relation to repeated dose systemic effects and reproductive toxicity. The U.S. Department of Health and Human Services is a little more specific. Regarding developmental and reproductive toxicity they say that there is insufficient evidence for a conclusion. Low dose developmental toxicity (in rats) shows limited evidence for adverse effects. Developmental toxicity for infants, children, and fetuses showed some concern for adverse effects, and there is negligible concern for reproductive toxicity in adult men and women and malformations in newborns. All of this basically means that there is a need for more research to be done in order to nail down the long-term, low-dose effects. Kind of leaves us in the lurch, doesn’t it? This is often the case once you start really digging into something like this. There really isn’t the data to say that the substance is going to make your three year old son need to shave his back or that it’s OK to eat a pound of this white, hospital-smelling powder every day without side effects.

So, now what? Well, I believe that it’s a good idea to avoid as many man-made chemicals as you can, especially if the alternatives are inexpensive regardless of weather or not the science catches up with the possible deleterious effects of a specific chemical. To minimize BPA exposure there are a couple of simple things that can be done. If you already own polycarbonate bottles (like the ubiquitous Nalgenes that the hippies around here carry wherever they go) labeled #7 on the bottom, wash them by hand with mild dishwashing soap, not in the dishwasher, to avoid degrading the plastic and increasing leeching of BPA. Don’t fill them up with hot coffee, tomato juice, or booze. Remember that even plastic does not last forever. Look for cracks or cloudiness on your drinking bottles, and if they look like they’ve been in a rock-tumbler for a couple of weeks then it’s time to replace them with something else. If you have an infant use glass baby bottles or plastic bag inserts which are made of polyethylene, or switch to polypropylene bottles that are labeled #5 and have a milky appearance rather than being clear. Choose soups, juice and other food packaged in cardboard brick cartons instead of cans. And, of course, you can always try to eat fresh foods in season instead of the canned foods that you keep in your fallout shelter, but that's just crazy talk, I know.

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