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Bisphenol A
- April 18, 2008 11:27 AM |
- By Your Voice
The federal government is expected to designate the chemical Bisphenol A a dangerous substance. This shortly after many major retailers pulled plastic products containing the chemical off their shelves.
What is Bisphenol A? What are the dangers associated with the chemical? What products can it be found in?
Dr. Joe Schwarcz is the director of McGill University’s Office for Science and Society.
Dr. Joe Schwarcz
On Monday, April 21 he took your questions on Bisphenol A.
Read his responses below.
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Comments (17)
How can know exactly which plastic products contain bisphenol A? Has a list been compiled?
Joe Schwarcz: Bisphenol A is used to make polycarbonates, identifiable by the #7 in the recycling logo. But not all #7s are polycarbonate. BPA is also used to make the plastic liners used in most food cans but there is no way to identify these.
What plastics are safe / not-safe for long term food/beverage storage?
What plastics are safe / not-safe for microwave cooking?
Joe Schwarcz: There is no evidence that any plastic is unsafe, but theoretical concerns have been raised about chemicals leaching out of plastic containers. These concerns revolve around bisphenol A, phthalates and styrene. Polyethylene, (#2 and 4) and polypropylene (#5) and PET (#1) do not leach any of these and are the best choice for anyone who is concerned.
Bisphenol A is a harmful chemical in plastic. Is there other materials other then plastic that this Bisphenol A can be found in? Why hasn't the government noticed this before?
Joe Schwarcz: “Harmful” is open to interpretation. There is no evidence that bisphenol A has caused any harm to humans but there are theoretical concerns based upon animal and laboratory experiments. BPA is also used to formulate the protective liners used in many food cans.
Since food sits in cans for much longer periods of time than milk sits in baby bottles, is food from cans with liners containing Bisphenol A a health concern. Are particular types of canned food more susceptible to absorbing Bisphenol A from can liners. How long does Bisphenol A stay active in the human body after being ingested.
Joe Schwarcz: Bisphenol A is very quickly metabolized in the human body, so risk, if there is any, would be associated only with continuous exposure. Canned food could constitute such exposure, with acidic foods such as tomato products increasing the chance for leaching. The industry is looking into alternatives for can liners but it is a technical challenge.
My wife and I store boiled water for baby formula, after it has cooled to room temperature, in bottles that contain BPA. It is used within a day. Is it safe to do so?
Joe Schwarcz: If there is an issue with BPA, which is debatable, then that issue is most relevant to infants. To be on the extreme safe side it is better to use glass, polyethylene or polyester bottles for babies.
Should I be diligent about removing all of these products from my kitchen? How great a risk is this? Would it be smarter to get rid of all the plastic, and start afresh?
Joe Schwarcz: The risk is minute and in my view only an issue with infants and possibly with people who have or have had a hormone-linked cancer.
I certainly do not advocate getting rid of all plastic container, there is no scientific justification for that.
Most of my food storage containers (tupperware) have number 5 on the bottom in a triangle. Do these contain BPA? If so, are they unsafe to use? Is it unsafe to wash them in hot water or heat in the microwave?
Joe Schwarcz: Number 5 refers to polypropylene and there is no safety issue with this plastic at all.
I've heard about different grades of Bisphenol A. with medical grade being the highest. Is there anything to this? Are these superior grades any less dangerous? Has Health Canada made any distinctions?
Joe Schwarcz: There is nothing to this. Bisphenol A is one specific compound and does not come in “grades.”
I work at a chemical plant and produce Bisphenol A in massive quantities . What exactly should I be worried about and how can I get tested to see if I have suffered any physical damage ? I'm willing to take part in any studies on this subject . Thank you .
Joe Schwarcz: The only occupational effects of bisphenol A that have been documented, and very rarely, include contact dermatitis and possible respiratory problems due to exposure to bisphenol A dust.
There is no evidence of any long term effects in workers exposed to BPA, and of course exposure here is much greater than the general public. No testing is available for any damage that may be caused specifically by BPA.
Given the scale of BPA production and the numerous facilities involved in production around the world, any significant effect due to occupational exposure would already have been noted.
I understand that we should not be heating milk in plastic bottles but what about sterilizing the bottles after use and then waiting for them to dry? I have a breast pump with plastic attachments which need to be steam sterilized by heating them for 2 minutes. I wait for them to dry before using them again - do you think this is ok?
Joe Schwarcz: The bottles of concern are those made of polycarbonate (recycling logo #7) and it is best to use glass or other plastics instead. As far as the breast pump goes, the contact time would be minimal and would not present an issue.
What are the effects (proven and suspected) on humans of this dangerous chemical?
Joe Schwarcz: There certainly is no proven effect. The theoretical concern revolves around the fact that BPA has estrogen-like effects and if infants are exposed it may trigger effects that are manifested later in life. These could include hormone-sensitive cancers, endocrine problems and perhaps behavioural ones. But all of this is highly speculative.
At this point, the only measure that may be justified is to not use polycarbonate bottles for feeding babies.
What function did bisphenol A serve in plastic products, and is much known about the safety of any alternatives?
Joe Schwarcz: Bisphenol A is an integral component of polycarbonate plastics. You cannot make this plastic without it. Of course there are numerous plastics other than polycarbonate and those do not require BPA. But polycarbonates are clear and tremendously strong, difficult to reproduce with other plastics. But it is only the food contact items that are an issue and for those there are substitutes such as polyethylene, polypropylene and polyester.
We have a bottled spring water service and the water comes in plastic bottles with the 7 in the recycling symbol and seem to be easily identifiable as having BPA. Is drinking this water hazardous for my 4 year old son and pregnant wife? Should we stop getting this water and go to tap water?
Joe Schwarcz: If there is a risk with BPA, it would be during gestation and infancy, but of course it is debatable whether there is a risk. To be prudent it would be a good idea for young children and pregnant women to use plastics other than polycarbonate or drink tap water. If you are concerned about water quality, use a jug type of filter.
On the bottom of some, but not all, plastic containers, there seems to be some kind of classification system - you see a number inside the 'recycle triangle', along with some letters below it. What does it all mean?
Joe Schwarcz: The number identifies the type of plastic so the recyclers can separate the plastics and recycle these appropriately. This has nothing to do with safety.
Following an in-depth risk assessment, Health Canada has found polycarbonate drinking bottles to pose no significant health risk to adults, yet several retailers have replaced them with alternatives such as acrylic bottles. Has an in-depth risk assessment been done on acrylic monomers leaching from these bottles?
Joe Schwarcz: Certainly not as extensively as BPA has been studied. But there is no evidence that acrylic monomers are estrogenic.
I have a number of "sippy cups" that my one-year old and three-year old daughters both drink from. Some of these cups are made from polycarbonate, while others are made from polyethylene (type 4) or polypropylene (type 5) plastics. Should I be concerned about these other types of plastic as well?
Joe Schwarcz: There is no concern about #4 or #5 so these would be the best choices.
Which types of plasitc bottles are safe to drink from?
Joe Schwarcz: The best are polyester (#1 in the recycling logo) or polyethylene (#2 or 4) although the concerns that have been raised about polycarbonate (#7) only apply to infants.