Dear Dr. Eva:

Thanks for your informative publication on bottled water. Sometime ago, I read an email circulated by John Hopkins Hospital, discouraging people from freezing plastic water bottles. According to the article, the dioxins contained in the plastic when released, are highly poisonous. Before reading their mail, I believed that there was something wrong in freezing water that way. I would love to hear your comments.

Sincerely,

LB

Dear LB,

I think that the chemical you are thinking of is not dioxin (which is present in weed killers), but Bisphenol A, also called BPA. BPA is a chemical used to make clear, hard plastics and epoxy resins. Hard plastics are used in many common food-related household items like reusable water bottles, baby bottles, food containers, pitchers, and plastic cutlery. This type of plastic is also found in eyeglass lenses, CDs, DVDs, computers and many other manufactured goods. Epoxy resin linings are used to coat the inside of metal products such as food cans, bottle tops, and water supply pipes. The linings keep the metal can separate from the food so the metal does not dissolve into the food.

BPA Exposure: how it happens – Traces of BPA remain in polycarbonate products and epoxy linings after manufacture, and the BPA can be released into food and beverages. Canned foods and drinks that have been stored or heated in polycarbonate containers or epoxy-lined cans are the main source of exposure to BPA.

Infants are at greater risk for BPA exposure because infants’ diets consist mostly of infant formula which is packaged in epoxy-lined cans. Infants may also be fed this formula in polycarbonate baby bottles, further increasing their BPA exposure.

Is exposure to Bisphenol A dangerous? – The more I reviewed the scientific literature on BPA, the less solid information I found. It is not clear whether BPA is a danger to human health in the small amounts most people are exposed to through food. The clearest finding so far is that BPA exposure can change the pattern of brain and nerve development in very young lab animals. This suggests that we need to make particular efforts to ensure that babies and young children, and perhaps pregnant women as well, are not exposed to BPA.

Research looking into BPA exposure and adult health has not found any clear evidence that BPA is dangerous to non-pregnant adults.

How can people reduce their exposure to Bisphenol A? – Low level BPA exposure occurs in the general US population. Although it is unknown whether there is a health risk to adults, some people may want to reduce BPA exposure to their children or themselves. Infants are unable to eliminate BPA from their bodies as quickly as children or adults. This can lead a higher level of BPA.

For breastfeeding infants: in addition to the many other benefits of breastfeeding, avoiding canned formula and bottles will greatly decrease the infant’s BPA exposure. Exposure can be limited even more by avoiding use of polycarbonate food containers and canned foods during breastfeeding.

For bottle feeding infants: Avoid using polycarbonate plastic baby bottles; use glass bottles instead.

Do not put boiling or very hot formula or other liquids in plastic bottles, and do not warm plastic baby bottles in a microwave.

Avoid liquid or powdered formula packaged in metal cans. Try to use powdered formula packaged in cardboard without epoxy liners.

For people of all ages: The largest exposure people have to BPA is taking it in by mouth from food packaging, epoxy linings of metal food and beverage cans, and plastic bottles. More chemicals are released if the plastic is warm or just washed.

Also:

• Store food in, and eat it from, glass, ceramic, or metal containers.
• Avoid heating foods in polycarbonate containers or placing hot foods in polycarbonate containers.
• Avoid the use of polycarbonate dishes and other tableware.
• Reduce the amount of food eaten from epoxy-lined cans.
• The safest thing, for multiple health reasons, is to eat fresh or frozen foods and always wash hands before eating.